外文文献 外文翻译 英文文献 用固定化反应器快速处理制革废水中难解有机及无机废物
污水处理外文文献
污水处理外文文献Wastewater treatment is a critical process that involves the removal of pollutants and contaminants from water, making it safe for discharge back into the environment or for reuse. This process is important because it ensures that water resources are not polluted or depleted, which can have severe consequences on the environment and public health. In this document, we will explore some important foreign language literature on wastewater treatment, its different types, and the various techniques used in the process.Types of Wastewater TreatmentGenerally, wastewater treatment can be classified into two categories: primary treatment and secondary treatment. Primary treatment involves the physical removal of large, suspended solids from wastewater. This process primarily relies on sedimentation and filtration techniques. Secondary treatment, on the other hand, is a biological process that involves the use of microorganisms to break down organic matter in wastewater. It usually follows primary treatment and is more effective at removing pollutants than primary treatment.Techniques Used in Wastewater TreatmentThere are several techniques used in the treatment of wastewater. Some of these techniques include:1. Biological Treatment: This is the most commonly used method in secondary treatment, and it involves the use of biological agents such as bacteria and microorganisms to degrade organic matter in wastewater. The process involves aerobic or anaerobic degradation of pollutants in wastewater. During this process, microorganisms convert organic matter into carbon dioxide and water.2. Chemical Treatment: This method involves adding chemicals, such as coagulants and flocculants, to wastewater to remove suspended solids and other contaminants. Chemical treatment is commonly used in primary treatment processes.3. Physical Treatment: This method involves the removal of solids and other particles from wastewater using physical processes such as sedimentation, filtration, and screening. Physical treatment is usually used at the beginning of the treatment process.4. Membrane Technology: This is a newer process in wastewater treatment that uses filters with tiny pores to separate contaminants from wastewater. It is mainly used in tertiary treatment, which is the final stage of treatment before discharge.Foreign Language Literature on Wastewater TreatmentThere are several foreign language literature sources on wastewater treatment. Some of the most important ones include:1. The Water Environment Federation: This is a non-profit organization that provides publications and research on wastewater treatment. They offer peer-reviewed journals and books that provide valuable information on the latest research and technology in wastewater treatment.2. Water Research Journal: This is an international journal that publishes research on water treatment and related fields. It offers peer-reviewed articles on topics such as wastewater engineering, water quality, and water resources.3. Environmental Science and Technology Journal: This is a publication that covers various aspects of environmental science and technology, including water treatment. It providespeer-reviewed articles on research in environmental science and technology.ConclusionWastewater treatment is an essential process that ensures that water resources are not polluted or depleted. It involves different treatment methods, such as physical, chemical, and biological treatment. Among the different sources of literature on wastewater treatment, the Water Environment Federation, the Water Research Journal, and the Environmental Science and Technology Journal are valuable sources of information. Newadvances in technology mean that wastewater treatment is becoming more efficient and effective, ensuring the safe discharge of treated wastewater back into the environment or for reuse.。
污水处理工业废水回用中英文对照外文翻译文献
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污水处理厂 外文文献
ENVIRONMENTAL BIOTECHNOLOGYOne-stage partial nitritation/anammox at15°Con pretreated sewage:feasibility demonstration at lab-scale Haydée De Clippeleir&Siegfried E.Vlaeminck&Fabian De Wilde&Katrien Daeninck&Mariela Mosquera&Pascal Boeckx&Willy Verstraete&Nico BoonReceived:26November2012/Revised:28January2013/Accepted:30January2013#Springer-Verlag Berlin Heidelberg2013Abstract Energy-positive sewage treatment can beachieved by implementation of oxygen-limited autotrophicnitrification/denitrification(OLAND)in the main water line,as the latter does not require organic carbon and thereforeallows maximum energy recovery through anaerobic diges-tion of organics.To test the feasibility of mainstreamOLAND,the effect of a gradual temperature decrease from29to15°C and a chemical oxygen demand(COD)/Nincrease from0to2was tested in an OLAND rotatingbiological contactor operating at55–60mg NH4+–NL−1 and a hydraulic retention time of1h.Moreover,the effectof the operational conditions and feeding strategies on thereactor cycle balances,including NO and N2O emissionswere studied in detail.This study showed for the first timethat total nitrogen removal rates of0.5g NL−1day−1can bemaintained when decreasing the temperature from29to15°Cand when low nitrogen concentration and moderate CODlevels are treated.Nitrite accumulation together with elevatedNO and N2O emissions(5%of N load)were needed to favoranammox compared with nitratation at low free ammonia(<0.25mg NL−1),low free nitrous acid(<0.9μg NL−1),and higher DO levels(3–4mg O2L−1).Although the total nitrogen removal rates showed potential,the accumulation of nitrite and nitrate resulted in lower nitrogen removal efficiencies (around40%),which should be improved in the future. Moreover,a balance should be found in the future between the increased NO and N2O emissions and a decreased energy consumption to justify OLAND mainstream treatment. Keywords Energyself-sufficient.Nitrospira.Nitricoxide. Nitrous oxide.DeammonificationIntroductionCurrently,around40full-scale one-stage partial nitrita-tion/anammox plants are implemented to treat highly loaded nitrogen streams devoid in carbon(Vlaeminck et al.2012). This process,known under the acronyms oxygen-limited autotrophic nitrification/denitrification(OLAND)(Kuai and Verstraete1998),deammonification(Wett2006),com-pletely autotrophic nitrogen removal over nitrite(Third et al. 2001),etc.,showed highly efficient and stable performance when treating digestates from sewage sludge treatment plants and industrial wastewaters(Wett2006;Abma et al. 2010;Jeanningros et al.2010).For clarity,one-stage partial nitritiation/anammox processes will be referred to as OLAND in this work.From an energy point of view,the implementation of the OLAND process for the treatment of sewage sludge digestate decreased the net energy consump-tion of a municipal wastewater treatment plant(WWTP)by 50%,with a combination of a lower aeration cost in the side stream and the opportunity to recover more organics from the mainstream(Siegrist et al.2008).Moreover,when co-digestion of kitchen waste was applied,an energyneutral Electronic supplementary material The online version of this article(doi:10.1007/s00253-013-4744-x)contains supplementary material,which is available to authorized users.H.De Clippeleir:S.E.Vlaeminck:F.De Wilde:K.Daeninck:M.Mosquera:W.Verstraete:N.Boon(*)Laboratory for Microbial Ecology and Technology(LabMET),Ghent University,Coupure Links653,9000Gent,Belgiume-mail:Nico.Boon@UGent.beP.BoeckxLaboratory of Applied Physical Chemistry(ISOFYS),Ghent University,Coupure Links653,9000Gent,BelgiumAppl Microbiol BiotechnolDOI10.1007/s00253-013-4744-xWWTP was achieved(Wett et al.2007).To fully recover the potential energy present in wastewater,a first idea of a new sustainable wastewater treatment concept was reported (Jetten et al.1997).Recently,a“ZeroWasteWater”concept was proposed which replaces the conventional activated sludge system by a highly loaded activated sludge step (A-step),bringing as much as organic carbon(chemical oxygen demand(COD))as possible to the solid fraction, and a second biological step(B-step)removing the residual nitrogen and COD with a minimal energy demand (Verstraete and Vlaeminck2011).Subsequently,energy is recovered via anaerobic digestion of the primary and sec-ondary sludge.For the B-step in the main line,OLAND would potentially be the best choice as this process can work at a low COD/N ratio,allowing maximum recovery of COD in the A-step.Moreover,it was calculated that if OLAND is implemented in the main water treatment line and a maximum COD recovery takes place in the A-step,a net energy gain of the WWTP of10Wh inhabitant equivalent (IE)−1day−1is feasible(De Clippeleir et al.2013).To allow this energy-positive sewage treatment,OLAND has to face some challenges compared with the treatment of highly loaded nitrogen streams(>250mg NL−1).A first difference is the lower nitrogen concentration to be removed by OLAND.Domestic wastewater after advanced concen-tration will still contain around30–100mg NL−1and113–300mg CODL−1(Metcalf and Eddy2003;Tchobanoglous et al.2003;Henze et al.2008).High nitrogen conversion rates(around400mg NL−1day−1)by the OLAND process can be obtained at nitrogen concentrations of30–60mg N L−1and at low hydraulic retention times(HRT)of1–2h(De Clippeleir et al.2011).A second challenge is the low tem-perature at which OLAND should be operated(10–15°C compared with34°C).Several studies already described the effect of temperature on the activity of the separate micro-bial groups(Dosta et al.2008;Guo et al.2010;Hendrickx et al.2012).Only a few studies showed the long-term effect of a temperature decrease below20°C on the microbial bal-ances of anoxic and aerobic ammonium-oxidizing bacteria (AnAOB and AerAOB)and nitrite-oxidizing bacteria (NOB)at nitrogen concentrations above100mg NL−1 (Vazquez-Padin et al.2011;Winkler et al.2011).However, the combination of low temperature and low nitrogen con-centration was never tested on a co-culture of AerAOB, AnAOB,and NOB before.At temperatures around15°C, maintaining the balance between NOB and AnAOB and the balance between NOB and AerAOB will get more challeng-ing since the growth rate of NOB will become higher than the growth rate of AerAOB(Hellinga et al.1998). Therefore,it will not be possible to wash out NOB based on overall or even selective sludge retention.The third and main challenge in this application will therefore be the suppression of NOB at temperature ranges of10–20°C and at nitrogen concentration ranges of30–60mg NL−1 (low free ammonia and low nitrous acid),which was not shown before.A final fourth challenge will include the higher input of organics at moderate levels of90–240mg biodegradable CODL−1in the wastewater.Depending on the raw sewage strength,COD/N ratios between2and3are expected after the concentration step,which is on the edge of the described limit for successful OLAND(Lackner et al. 2008).The presence of organics could result in an extra competition of heterotrophic denitrifiers with AerAOB for oxygen or with AnAOB for nitrite or organics,since certain AnAOB can denitrify consuming organic acids (Kartal et al.2007).In this study,the challenges2to4,were evaluated in an OLAND rotating biological contactor(RBC).This reactor at 29°C was gradually adapted over24,22,and17to15°C under synthetic wastewater conditions(60mg N L−1, COD/N of0).Additionally,the COD/N ratio of the influent was increased to2by supplementing NH4+to diluted sewage to simulate pretreated sewage.The effect of the operational conditions and feeding strategies on the reactor cycle balan-ces,including gas emissions and microbial activities were studied in detail.An alternative strategy to inhibit NOB activity and as a consequence increase AnAOB activity at low temperatures based on NO production was proposed. Materials and methodsOLAND RBCThe lab-scale RBC described by De Clippeleir et al.(2011) was further optimized at29°C by an increase in the influent nitrogen concentration from30to60mg NL−1and a limitation of the oxygen input through the atmosphere by covering the reactor before this test was started.The reactor was based on an air washer LW14(Venta,Weingarten, Germany)with a rotor consisting of40discs interspaced at 3mm,resulting in a disc contact surface of1.32m2.The reactor had a liquid volume of2.5L,immersing the discs for 55%.The latter was varied over the time of the experiment. The reactor was placed in a temperature-controlled room. The DO concentration was not directly controlled.In this work,continuous rotation was applied at a constant rotation speed of3rpm,which allowed mixing of the water phase. RBC operationThe RBC was fed with synthetic wastewater during phases I to VII.From phase VIII onwards,the COD/N was gradually increased(phases VIII–X)to2(phases XI–XIII).The syn-thetic influent of an OLAND RBC,consisted of(NH4)2SO4 (55–60mg NL−1),NaHCO3(16mg NaHCO3mg−1N),andAppl Microbiol BiotechnolKH2PO4(10mg PL−1).Pretreated sewage was simulated by diluting raw sewage of the communal WWTP of Gent, Belgium(Aquafin).The raw wastewater after storage at 4°C and settlement contained23–46mg NH4+–NL−1, 0.2–0.4mg NO2−–NL−1,0.4–2.7mg NO3−–NL−1,23–46mgKjeldahl–NL−1,3.8–3.9mg PO43−–PL-1,26–27mg SO42−–S L−1,141–303mg COD tot L−1,and74–145mg COD sol L−1.The raw sewage was diluted by factors2–3to obtain COD values around110mg COD tot L−1and by addition of(NH4)2SO4to obtain final COD/N values around2.The reactor was fed in a semi-continuous mode:two periods of around10min/h for phases I–XI and one period of20min/h for phases XII and XIII.The influent flow range varied from47to65Lday−1and the reactor volume from3.7to2.5L(during78and55% submersion,respectively).Corresponding HRTare displayed in Tables1and2.Reactor pH,DO,and temperature were daily monitored and influent and effluent samples were taken at least thrice a week for ammonium,nitrite,nitrate,and COD analyses. Detection of AerAOB,NOB,and AnAOB with FISHand qPCRFor NOB and AnAOB,a first genus screening among the most commonly present organisms was performed by fluo-rescent in-situ hybridization(FISH)on biomass of days1 (high temperature)and435(low temperature and COD presence).A paraformaldehyde(4%)solution was used for biofilm fixation,and FISH was performed according to Amann et al.(1990).The Sca1309and Amx820probes were used for the detection of Cand.Scalindua and Cand. Kuenenia&Brocadia,respectively,and the NIT3and Ntspa662probes and their competitors for Nitrobacter and Nitrospira,respectively(Loy et al.2003).This showed the absence of Nitrobacter and Scalindua(Table S1in the Electronic supplementary material(ESM)).Biomass sam-ples(approximately5g)for nucleic acid analysis were taken from the OLAND RBC at days1,60,174,202,306,385, 399,and413of the operation.DNA was extracted using FastDNA®SPIN Kit for Soil(MP Biomedicals,LLC), according to the manufacturer’s instructions.The obtained DNA was purified with the Wizard®DNA Clean-up System (Promega,USA)and its final concentration was measured spectrophotometrically using a NanoDrop ND-1000spec-trophotometer(Nanodrop Technologies).The SYBR Green assay(Power SyBr Green,Applied Biosystems)was used to quantify the16S rRNA of AnAOB and Nitrospira sp.and the functional amoA gene for AerAOB.The primers for quantitative polymerase chain reactions(qPCR)for detection of AerAOB,NOB,and AnAOB were amoA-1F–amoA-2R (Rotthauwe et al.1997),NSR1113f–NSR1264r(Dionisi et al. 2002),and Amx818f–Amx1066r(Tsushima et al.2007),re-spectively.For bacterial amoA gene,PCR conditions were: 40cycles of94°C for1min,55°C for1min,and60°C for 2min.For the amplification of Nitrospira sp.16S rRNA gene, 40cycles of95°C for1min,50°C for1min,and60°C for 1min were used while for AnAOB16S rRNA the PCR temperature program was performed by40cycles of15s at 94°C and1min at60°C.Plasmid DNAs carrying NitrospiraTable1Effect of temperature decrease on the operational conditions and performance of OLAND RBC reactorPhase I II III IV V VI VIIPeriod(days)1–2122–3536–6162–210210–263263–274275–306 Immersion level(%)78787878557855 Temperature(°C)29±224±122±0.617±1.216±0.915±0.814±0.4 Operational conditionsDO(mg O2L−1) 1.1±0.2 1.3±0.2 1.4±0.1 1.7±0.3 2.8±0.4 2.4±0.2 3.1±0.2 pH(−)7.5±0.17.5±0.17.5±0.17.6±0.17.7±0.17.7±0.17.8±0.1 HRT(h) 1.85±0.04 1.84±0.09 1.73±0.04 1.86±0.11 1.09±0.02 1.57±0.02 1.09±0.02 FA(mg NL−1)0.35±0.180.36±0.180.34±0.140.36±0.130.25±0.160.33±0.170.13±0.04 FNA(μg NL−1)0.3±0.10.3±0.20.4±0.20.4±0.10.9±0.40.6±0.10.9±0.2 PerformanceTotal N removal efficiency(%)54±552±549±934±936±936±942±4 Relative NO3−prod(%of NH4+cons a)7±17±17±114±618±916±321±4 Relative NO2−accum(%of NH4+cons)2±43±45±515±530±826±631±5 AerAOB activity(mg NH4+–NL−1day−1)267±38267±49260±52260±53811±229460±44986±71 NOB activity(mg NO2–NL−1day−1)0±00±00±09±1260±9420±585±25 AnAOB activity(mg N tot L−1day−1)412±38403±37368±76248±67448±117305±74529±75DO dissolved oxygen,HRT hydraulic retention time,F A free ammonia,FNA free nitrous acid,cons consumption,prod production,accum accumulation,tot totala NH4+consumption is corrected for nitrite accumulationAppl Microbiol Biotechnoland AnAOB16S rRNA gene and AerAOB functional AmoA gene,respectively,were used as standards for qPCR.All the amplification reactions had a high correlation coefficient (R2>0.98)and slopes between−3.0and−3.3.Detailed reactor cycle balancesFor the measurements of the total nitrogen balance,including the NO and N2O emissions,the OLAND RBC was placed in a vessel(34L)which had a small opening at the top(5cm2).In this vessel,a constant upward air flow(around1ms−1or0.5L s-1)was generated to allow calculations of emission rates.On the top of the vessel(air outlet),the NO and N2O concentra-tion was measured,off-and online,respectively.NH3emis-sions were negligible in a RBC operated at about2mg NH3–NL−1(Pynaert et al.2003).Since FA levels in the currentstudy are about ten times lower,NH3emissions were not included.In the water phase,ammonium,nitrite,nitrate,hy-droxylamine(NH2OH),N2O,and COD concentrations were measured.Moreover,DO concentration and pH values were monitored.The air flow was measured with Testo425hand probe(Testo,Ternat,Belgium).Chemical analysesAmmonium(Nessler method)was determined according to standard methods(Greenberg et al.1992).Nitrite and nitrate were determined on a761compact ion chromatograph equipped with a conductivity detector(Metrohm,Zofingen, Switzerland).Hydroxylamine was measured spectrophoto-metrically(Frear and Burrell1955).The COD was determined with NANOCOLOR®COD1500en NANOCOLOR®COD 160kits(Macherey-Nagel,Düren,Germany).The volumetric nitrogen conversion rates by AerAOB,NOB,and AnAOB were calculated based on the measured influent and effluent compositions and the described stoichiometries,underestimat-ing the activity of AnAOB by assuming that all COD removed was anoxically converted with nitrate to nitrogen gas (Vlaeminck et al.2012).DO and pH were measured with respectively,a HQ30d DO meter(Hach Lange,Düsseldorf, Germany)and an electrode installed on a C833meter (Consort,Turnhout,Belgium).Gaseous N2O concentrations were measured online at a time interval of3min with a photo-acoustic infrared multi-gas monitor(Brüel&Kjær, Model1302,Nærem,Denmark).Gas grab samples were taken during the detailed cycle balance tests for NO detec-tion using Eco Physics CLD77AM(Eco Physics AG, Duernten,Switzerland),which is based on the principle of chemiluminescence.For dissolved N2O measurements,a1-mL filtered(0.45μm)sample was brought into a7-mL vacutainer(−900hPa)and measured afterwards by pressure adjustment with He and immediate injection at21°C in a gas chromatograph equipped with an electron capture detector (Shimadzu GC-14B,Japan).Table2Effect of COD/N increase on the operational conditions and performance of OLAND RBC reactorPhase VIII IX X XI XII XIIIPeriod(days)355–361362–369370–374375–406407–421422–435 Immersion level(%)555555555555COD/N(-)0.51 1.5222 Feeding regime(pulsesh−1)222211 Operational conditionsDO(mg O2L−1) 2.9±0.3 2.5±0.6 2.4±0.3 3.0±0.7 3.6±0.3 3.2±0.3 pH(−)7.8±0.027.7±0.17.6±0.027.6±0.17.6±0.27.6±0.1 HRT(h) 1.06±0.11 1.03±0.020.92±0.020.94±0.05 1.10±0.05 1.06±0.2 FA(mg NL−1)0.10±0.050.04±0.050.15±0.050.21±0.100.23±0.120.04±0.02 FNA(μg NL−1)0.4±0.10.2±0.20.2±0.010.3±0.10.2±0.10.6±0.2 PerformanceTotal N removal efficiency(%)36±545±1823±328±623±1342±3 Relative NO3−prod(%of NH4+cons a)42±543±1263±250±662±1846±6 Relative NO2−accum(%of NH4+cons)20±410±105±18±37±413±6 AerAOB activity(mg NH4+–NL−1day−1)592±15446±31238±28352±73289±138600±204 NOB activity(mg NO2−–NL−1day−1)257±19294±81465±60352±84427±115394±76 AnAOB activity(mg N tot L−1day−1)385±86452±205262±39355±73281±159481±73COD removal rates were negligible in all phasesDO dissolved oxygen,HRT hydraulic retention time,F A free ammonia,FNA free nitrous acid,cons consumption,prod production,accum accumulation,tot totala NH4+consumption is corrected for nitrite accumulationAppl Microbiol BiotechnolResultsEffect of temperature decreaseDuring the reference period (29°C),a well-balanced OLAND performance (Fig.1;Table 1)was reached with minimal nitrite accumulation (2%)and minimal nitrate production (7%).This was reflected in an AerAOB/AnAOB activity ratio of 0.6(Table 1,phase I).The total nitrogen removal rate was on average 470mg N L −1day −1or 1314mg Nm −2day −1,and the total nitrogen removal efficiency was 54%.Decreasing the temperature from 29to 24°C and further to 22°C over the following 40days,did not result in anysignificant changes of the operational conditions (Table 1;phases I –III),performance of the reactor (Fig.1)or abun-dance of the bacterial groups (qPCR;Fig.S1in the ESM ).However at 17°C,a decrease in total nitrogen removal efficiency was observed (Table 1;phase IV).An imbalance between the AerAOB and the AnAOB was apparent from a stable AerAOB activity yet a declining AnAOB activity.Moreover,NOB activity was for the first time detected in spite of free ammonia (FA)and free nitrous acid (FNA)con-centrations did not change (Table 1;phase IV).Moreover,no significant differences in abundance of NOB,AerAOB,and AnAOB could be detected with qPCR (Fig.S1in the ESM ).However,DO concentrations started to increase during that period from 1.4to 1.7mg O 2L −1.As the availabilityofFig.1Phases I –VII:effect of temperature decrease on the volumetric rates (top )and nitrogen concentrations (bottom )Appl Microbiol Biotechnoloxygen through the liquid phase did not seem to be satisfac-tory to counteract the decrease in ammonium removal effi-ciency,the immersion level was lowered to55%to increase the availability of oxygen through more air-biofilm contact surface.Consequently,the volumetric loading rate increased (factor1.7)due to the decrease in reactor volume(day210, Fig.1).This action allowed higher ammonium removal effi-ciencies due to higher AerAOB activities(factor3).AnAOB activity increased with a similar factor as the volumetric loading rate(1.8compared with1.7)consequently resulting in an increased imbalance between these two groups of bac-teria(Table1;phase V).Moreover,although the FNA in-creased with a factor2,the NOB activity increased with a factor7,resulting in a relative nitrate production of30% (Table1;phase V).As NOB activity prevented good total nitrogen removal efficiencies,the immersion level was in-creased again to78%(day263;Fig.1).This resulted indeed in a lower NOB activity(Table1;phase VI).However,also the AerAOB activity decreased with the same factor,due to the lower availability of atmospheric oxygen.Therefore,the reactor was subsequently operated again at the lower immer-sion level(55%)to allow sufficient aerobic ammonium conversion.The latter allowed a stable removal efficiency of 42%.The AnAOB activity gradually increased to a stable anoxic ammonium conversion rate of529mg NL−1day−1. During the synthetic phase,no changes in AerAOB, AnAOB,and NOB abundance were measured with qPCR (Fig.S1in the ESM).The effluent quality was however not optimal as still high nitrite(around15mg NL−1)and nitrate (around13mg NL−1)levels were detected.Effect of COD/N increaseThe synthetic feed was gradually changed into pretreated sewage by diluting raw sewage and adding additional nitro-gen to obtain a certain COD/N ratio.During the first3weeks of this period(Fig.2),the COD/N ratio was gradually increased from0.5to2.Due to the short adaptation periods (1week per COD/N regime),the performance was unstable (Fig.2;Table2,phases VIII–XI).Compared with the end of the synthetic period(phase VII),operation at a COD/N ratio of2(phase XI)resulted in a sharp decrease in nitrite accu-mulation(Fig.2)and an increase in the ammonium and nitrate levels.This indicated increased NOB activity(factor 4),decreased AerAOB(factor3)and decreased AnAOB (factor2)activity(Tables1and2).To allow higher nitrogen removal rates,the HRT was increased from0.94to1.1h,by decreasing the influent flow rate.Moreover,the feeding regime was changed from two pulses of10min in1h to one period of20min/h.These actions did not significantly decrease the effluent nitrogen concentration(Fig.2)and did not influence the microbial activities(Table2,phase XII). Therefore the loading rate was again increased to the levels before phase XII.However,the single-pulse feeding wasmaintained.This resulted in high ammonium removal effi-ciencies and therefore low ammonium effluent concentra-tion around dischargeable level(4±1mg NH4+–NL−1; Fig.2).Nitrate and nitrite accumulation were not counter-acted by denitrification as only0.02mg CODL−1day−1wasremoved.Therefore,nitrite and nitrate levels were still toohigh to allow effluent discharge.The total nitrogen removalefficiency(42%)and rate(549±83mg NL−1day−1or1,098±106mgNm−2day−1)at COD/N ratios of2wassimilar as during the synthetic period(phase VII).Comparedwith the reference period at29°C,the total nitrogen removalrate did not changed significantly(470±43versus549±83mgNL−1day−1at high and low temperatures,respectively).The22%lowered removal efficiency was merely due to anincreased nitrogen loading rate.Nitratation and NO/N2O emissionsAt the end of the synthetic phase(phase VII)and the end ofthe experiment(phase XIII),the total nitrogen balance of thereactor was measured.A total nitrogen balance was obtainedby measuring all nitrogen species(NH4+,NO2−,NO3−,NH2OH,and N2O)in the liquid phase and N2O and NO inthe gas phase.A constant air flow,diluting the emitted N2Oand NO concentrations was created over the reactor tomeasure gas fluxes over time.The effect of the loading rate,feeding pattern,and concentration of nitrite and ammoniumon the total nitrogen balance in the reactor were tested(Table3).NH2OH measurements showed low concentra-tions(<0.2mg NL−1)in all tests,making it difficult to linkthe profiles with the N2O emission.Lowering the loading rate by increasing the HRT(Table3,test B)increased the DO values and allowed higherDO fluctuations over time at synthetic conditions.Moreover,NOB activity increased significantly resultingin lower total nitrogen removal efficiencies and high levelsof nitrate in the effluent(Table3,test B).The relative N2Oemissions did not change and were relatively high(6%of Nload).However,the concentration of N2O in the liquid andin the gas phase decreased with a factor2(Table3).When pretreated sewage was fed to the reactor,theOLAND RBC was operated at lower nitrite concentration,while similar ammonium and nitrate concentrations wereobtained(Table3,test C).The lower nitrite concentrationshowever did not result in lower N2O emission rates.Whenthe feeding regime was changed to a more continuous-likeoperation(4pulses/h),the N2O emission increased signifi-cantly,while NO emission remained constant(Table3,testD).Due to the lower ammonium removal efficiency(65compared with81%),but similar relative nitrite and nitrateaccumulation rate,the total nitrogen removal efficiencydecreased.Appl Microbiol BiotechnolWhen a nitrite pulse was added just after feeding,about 20mg NO 2−–NL −1was obtained in the reactor.This did increase the NO and N 2O emissions significantly (p <0.05)compared with the same feeding pattern (Table 3,tests C –E).Although similar constant total nitrogen removal efficien-cies were obtained during this operation,a significant (p <0.05)decrease in the relative nitrate production was observed.The latter was mainly caused by a global increase in AnAOB activity.In the last test (F),the influent ammo-nium concentration was doubled,leading to higher ammo-nium and also FA concentrations (1±0.4mg N L −1compared with 0.1±0.4mg NL −1).Due to overloading of the system,the total nitrogen removal efficiency decreased.However,at these conditions a lower relative nitrate pro-duction was obtained;due to a decrease in NOB and in-crease in AnAOB activity (Table 3,test F).Together with this,increased NO and N 2O emissions were observed.As the influence of the nitrogen loading and DO concentration could be considered minor in this test range (Fig.S2in the ESM ),these tests show a relation between increased NO emissions and decreased relative nitrate productions (Table 3).When the activity during the feeding cycle was studied in more detail,it could be concluded that the highest nitrogen conversion rates took place during the feeding period,which was characterized by a high substrate availability and high turbulence (Fig.3).As the HRT is only 1h,the reactor volume is exchanged in 20min.During this phase,ammo-nium increased,while nitrite and nitrate concentrations de-creased due to dilution (Figs.S3,S4,and S5in the ESM ).The NOB/AnAOB ratio was around 1,which means that NOB were able to take twice as much nitrite thanAnAOBFig.2Phases VIII –XIII:effect of COD/N increase on the volumetric rates (top )and nitrogen concentrations (bottom ).Data during the N balance tests (days 424–431)were not incorporated in the figure but are shown in Table 3Appl Microbiol BiotechnolTable 3Operational parameters and nitrogen conversion rates during the six different RBC operations which differ from feeding composition and feeding regime (volume at 2.5L and 50%immersion of the discs,days 307–309for synthetic feed,and days 424–431)Reactor phaseVII (synthetic)XIII (pretreated sewage)Test A a B C a D E -F Additive––––NO 2−NH 4+Feeding regime (pulses/h)221411Total N loading rate (mg NL −1day −1)1,1695851,3401,5541,7372,718Temperature water (°C)15±0.316±0.2*14±0.415±0.1*16±0.1*15±0.4DO (mg O 2L −1) 2.9±0.1 3.7±0.6* 4.0±0.1 3.2±0.1* 3.3±0.1* 3.2±0.1*pH (-)7.6±0.067.6±0.057.6±0.047.6±0.017.6±0.027.8±0.02*Ammonium out (mg NL −1)9±1 1.4±1*11±319±3*12±158±4*Nitrite out (mg NL −1)14±213±16±16±0.418±2*9±0.3*Nitrate out (mg NL −1)17±337±6*18±216±1*18±0.420±0.4NH 4+oxidation rate (mg NL −1day −1)895±22509±2*1,051±73957±891,053±161,285±93*Relative nitrite accumulation (%)25±320±1*14±315±18±4*15±1Relative nitrate production (%)36±876±6*48±147±342±2*34±3*Total efficiency (%)38±417±4*35±328±4*32±227±4*AerAOB activity (mg NH 4+–NL −1day −1)658±88469±17*827±44781±57795±30938±46*NOB activity (mg NO 2−–NL −1day −1)174±59299±28*375±38342±24*362±13277±18*AnAOB activity (mg N tot L −1day −1)205±3849±13*234±20218±29263±15*354±49*N 2O in liquid (μg NL −1)64±4630±22*78±12104±29*61±1374±4NO emission (mg Nday −1)0.53±0.03n.d.0.66±0.060.74±0.08 1.65±0.18*0.82±0.1*N 2O emission (mg Nday −1)151±2893±23*170±19179±6*274±37*202±18*%N 2O emission on loading5.1±1.06.4±1.6*5.0±0.64.5±0.2*6.2±0.8*3.0±0.3*aReference period for synthetic and pretreated sewage*p <0.05,significant differences compared with referenceperiod Fig.3Detailed NO/N 2Omonitoring during the reference test (Table 3,test C)and when nitrite was pulsed (Table 3,test E)and effect on AerAOB,AnAOB,and NOB activity during the different phases of the feeding cycle.Significant differences in AerAOB,AnAOB,NOB,and NO/N 2O concentration compared with the reference period areindicated with asterisks ,circles ,double quotation mark ,and plus sign ,respectivelyAppl Microbiol Biotechnol。
污水处理工业废水回用中英文对照外文翻译文献
(文档含英文原文和中文翻译)中英文资料对照外文翻译Catalytic strategies for industrial water re-useAbstractThe use of catalytic processes in pollution abatement and resource recovery is widespread and of significant economic importance [R.J. Farrauto, C.H. Bartholomew, Fundamentals of Industrial Catalytic Processes, Blackie Academic and Professional,1997.]. For water recovery and re-use chemo-catalysis is only just starting to make an impact although bio-catalysis is well established [J.N. Horan, BiologicalWastewater Treatment Systems; Theory and Operation, Chichester, Wiley,1990.]. This paper will discuss some of the principles behind developing chemo-catalytic processes for water re-use. Within this context oxidative catalytic chemistry has many opportunities to underpin the development of successful processes and many emerging technologies based on this chemistry can be considered .Keywords: COD removal; Catalytic oxidation; Industrial water treatment1.IntroductionIndustrial water re-use in Europe has not yet started on the large scale. However, with potential long term changes in European weather and the need for more water abstraction from boreholes and rivers, the availability of water at low prices will become increasingly rare. As water prices rise there will come a point when technologies that exist now (or are being developed) will make water recycle and re-use a viable commercial operation. As that future approaches, it is worth stating the most important fact about wastewater improvement–avoid it completely if at all possible! It is best to consider water not as a naturally available cheap solvent but rather, difficult to purify, easily contaminated material that if allowed into the environment will permeate all parts of the biosphere. A pollutant is just a material in the wrong place and therefore design your process to keep the material where it should be –contained and safe. Avoidance and then minimisation are the two first steps in looking at any pollutant removal problem. Of course avoidance may not be an option on an existing plant where any changes may have large consequences for plant items if major flowsheet revision were required. Also avoidance may mean simply transferring the issue from the aqueous phase to the gas phase. There are advantages and disadvantages to both water and gas pollutant abatement. However, it must be remembered that gas phase organic pollutant removal (VOC combustion etc.,) is much more advanced than the equivalent water COD removal and therefore worth consideration [1]. Because these aspects cannot be over-emphasised，a third step would be to visit the first two steps again. Clean-up is expensive, recycle and re-use even if you have a cost effective process is still more capital equipment that will lower your return on assets and make the process less financially attractive. At present the best technology for water recycle is membrane based. This is the only technology that will produce a sufficiently clean permeate for chemical process use. However, the technology cannot be used in isolation and in many (all) cases will require filtration upstream and a technique for handling the downstream retentate containing the pollutants. Thus, hybrid technologies are required that together can handle the all aspects of the water improvement process[6,7,8].Hence the general rules for wastewater improvement are:1. Avoid if possible, consider all possible ways to minimise.2. Keep contaminated streams separate.3. Treat each stream at source for maximum concentration and minimum flow.4. Measure and identify contaminants over complete process cycle. Look for peaks, which will prove costly to manage and attempt to run the process as close to typical values as possible. This paper will consider the industries that are affected by wastewater issues and the technologies that are available to dispose of the retentate which will contain the pollutants from the wastewater effluent. The paper will describe some of the problems to be overcome and how the technologies solve these problems to varying degrees. It will also discuss how the cost driver should influence developers of future technologies.2. The industriesThe process industries that have a significant wastewater effluent are shown in Fig. 1. These process industries can be involved in wastewater treatment in many areas and some illustrations of this are outlined below.Fig. 1. Process industries with wastewater issues.2.1. RefineriesThe process of bringing oil to the refinery will often produce contaminated water. Oil pipelines from offshore rigs are cleaned with water; oil ships ballast with water and the result can be significant water improvement issues.2.2. ChemicalsThe synthesis of intermediate and speciality chemicals often involve the use of a water wash step to remove impurities or wash out residual flammable solvents before drying.2.3. PetrochemicalsEthylene plants need to remove acid gases (CO2, H2S) formed in the manufacture process. This situation can be exacerbated by the need to add sulphur compounds before the pyrolysis stage to improve the process selectivity. Caustic scrubbing is the usual method and this produces a significant water effluent disposal problem.2.4. Pharmaceuticals and agrochemicalsThese industries can have water wash steps in synthesis but in addition they are often formulated with water-based surfactants or wetting agents.2.5. Foods and beveragesClearly use water in processing and COD and BOD issues will be the end result.2.6. Pulp and paperThis industry uses very large quantities of water for processing –aqueous peroxide and enzymes for bleaching in addition to the standard Kraft type processing of the pulp. It is important to realise how much human society contributes tocontaminated water and an investigation of the flow rates through municipal treatment plants soon shows the significance of non-process industry derived wastewater.3. The technologiesThe technologies for recalcitrant COD and toxic pollutants in aqueous effluent are shown in Fig. 2. These examples of technologies [2,6,8] available or in development can be categorised according to the general principle underlying the mechanism of action. If in addition the adsorption (absorption) processes are ignored for this catalysis discussion then the categories are:1. Biocatalysis2. Air/oxygen based catalytic (or non-catalytic).3. Chemical oxidation1. Without catalysis using chemical oxidants2. With catalysis using either the generation of _OH or active oxygen transfer. Biocatalysis is an excellent technology for Municipal wastewater treatment providing a very cost-effective route for the removal of organics from water. It is capable of much development via the use of different types of bacteria to increase the overall flexibility of the technology. One issue remains –what to do with all the activated sludge even after mass reduction by de-watering. The quantities involved mean that this is not an easy problem to solve and re-use as a fertilizer can only use so much. The sludge can be toxic via absorption of heavy metals, recalcitrant toxic COD. In this case incineration and safe disposal of the ash to acceptable landfill may be required. Air based oxidation [6,7] is very attractive because providing purer grades of oxygen are not required if the oxidant is free. Unfortunately, it is only slightly soluble in water, rather unreactive at low temperatures and, therefore, needs heat and pressure to deliver reasonable rates of reaction. These plants become capital intensive as pressures (from _10 to 100 bar) are used. Therefore, although the running costs maybe low the initial capital outlay on the plant has a very significant effect on the costs of the process. Catalysis improves the rates of reaction and hence lowers the temperature and pressure but is not able to avoid them and hence does not offer a complete solution. The catalysts used are generally Group VIII metals such as cobalt or copper. The leaching of these metals into the aqueous phase is a difficulty that inhibits the general use of heterogeneous catalysts [7]. Chemical oxidation with cheap oxidants has been well practised on integrated chemical plants. The usual example is waste sodium hypochlorite generated in chlor-alkali units that can be utilised to oxidise COD streams from other plants within the complex. Hydrogen peroxide, chlorine dioxide, potassium permanganate are all possible oxidants in this type of process. The choice is primarily determined by which is the cheapest at the point of use. A secondary consideration is how effective is the oxidant. Possibly the mostresearched catalytic area is the generation and use of _OH as a very active oxidant (advanced oxidation processes) [8]. There are a variety of ways of doing this but the most usual is with photons and a photocatalyst. The photocatalyst is normally TiO2 but other materials with a suitable band gap can be used [9,10]. The processes can be very active however the engineering difficulties of getting light, a catalyst and the effluent efficiently contacted is not easy. In fact the poor efficiency of light usage by the catalyst (either through contacting problems or inherent to the catalyst) make this process only suitable for light from solar sources. Photons derived from electrical power that comes from fossil fuels are not acceptable because the carbon dioxide emission this implies far outweighs and COD abatement. Hydroelectric power (and nuclear power) are possible sources but the basic inefficiency is not being avoided. Hydrogen peroxide and ozone have been used with photocatalysis but they can be used separately or together with catalysts to effect COD oxidation. For ozone there is the problem of the manufacturing route, corona discharge, which is a capital intensive process often limits its application and better route to ozone would be very useful. It is important to note at this point that the oxidants discussed do not have sufficient inherent reactivity to be use without promotion. Thus, catalysis is central to their effective use against both simple organics (often solvents) or complex recalcitrant COD. Hence, the use of Fenton’s catalyst (Fe) for hydrogen peroxide [11]. In terms of catalysis these oxidants together with hypochlorite form a set of materials that can act has ‘active oxygen transfer (AOT) oxidants’ in the presence of a suitable catalyst. If the AOT oxidant is hypochlorite or hydrogen peroxide then three phase reactions are avoided which greatly simplifies the flowsheet. Cheap, catalytically promoted oxidants with environmentally acceptable products of oxidation that do not require complex chemical engineering and can be produced efficiently would appear to offer one of the best solutions to the general difficulties often observed.3.1. Redox catalysis and active oxygen transferThe mechanism of catalytically promoted oxidation with hydrogen peroxide or sodium hypochlorite cannot be encompassed within one concept, however there are general similarities between the two oxidants that allows one to write a series of reactions for both (Fig. 3) [5]. This type of mechanism could be used to describe a broad range of reactions for either oxidant from catalytic epoxidation to COD oxidation. The inherent usefulness of the reactions is that;1. The reactions take place in a two-phase system.2. High pressure and temperature are not required.3. The catalytic surface can act as an adsorbent of the COD to be oxidised effectively increasing the concentration and hence the rate of oxidation.The simple mechanism shows the selectivity issue with this type of processes. The oxidant can simply be decomposed by the catalyst to oxygen gas – this reaction must be avoided because dioxygen will play no role in COD removal. Its formation is an expensive waste of reagent with oxygen gas ($20/Te) compared to the oxidant ($400–600/Te). To be cost competitive with alternative processes redox catalysis needs excellent selectivity.3.2. Technology mappingThe technologies so far described can be mapped [12] for their applicability with effluent COD concentration (measured as TOC) and effluent flow rate (m3 h-1). The map is shown in Fig. 4. The map outlines the areas where technologies are most effective. The boundaries, although drawn, are in fact fuzzier and should be only used as a guide. Only well into each shape will a technology start to dominate. The underlying cost model behind the map is based on simple assertions – at high COD mass flows only air/oxygen will be able to keep costs down because of the relatively low variable cost of the oxidant. At high COD concentrations and high flows only biological treatment plants have proved themselves viable –of course if done at source recovery becomes an option. At low flows and low COD levels redox AOT catalysis is an important technology – the Synetix Accent 1 process being an example of this type of process (see Fig. 5 for a simplified flowsheet). The catalyst operates under very controlled conditions at pH > 9 and hence metal leaching can be avoided (<5 ppb). The activity and selectivity aspects of the catalyst displayed in Fig. 3 can be further elaborated to look at the potential surface species. This simple view has been extended by a significant amount of research [3,4,5]. Now the mechanism of such a catalyst can be described in Fig. 6. The key step is to avoid recombination of NiO holes to give peroxy species and this can be contrasted with the hydrogen peroxide situation where the step may be characterized as oxygen vacancy filled. From both recombination will be facilitated by electronic and spatial factors. The range of application of the process is outlined below. From laboratory data some general types of chemical have been found suitable –sulphides, amines, alcohols, ketones, aldehydes, phenols, carboxylic acids, olefins and aromatic hydrocarbons. From industrial trials recalcitrant COD (nonbiodegradable) and sulphur compounds have been successfully demonstrated and a plant oxidising sulphur species has been installed and is operational.4. ConclusionsWastewater treatment processes are in the early stages of development. The key parameters at present are effectiveness and long term reliability. Many processes operating are in this stage, including the redox Accent TM is a trademark of the ICIGroup of Companies. catalysis systems. However,once proven, redox catalysis offers many advantages for COD removal from wastewater:1. The low capital cost of installation.2. Simple operation that can be automated.3. Flexible nature of the process – can be easily modified to meet changing demands of legislation.Hence it will be expected to develop into an important technology in wastewater improvement.AcknowledgementsThe author is grateful to Jane Butcher and Keith Kelly of Synetix for discussions on this paper. References[1] R.J. Farrauto, C.H. Bartholomew, Fundamentals of Industrial Catalytic Processes, Blackie Academic and Professional, 1997. F.E. Hancock / Catalysis Today 53 (1999) 3–9 9[2] J.N. Horan, Biological Wastewater Treatment Systems; Theory and Operation, Chichester, Wiley, 1990.[3] F.E. Hancock et al., Catalysis Today 40 (1998) 289.[4] F. King, F.E. Hancock, Catal. Today 27 (1996) 203.[5] J. Hollingworth et al., J. Electron Spectrosc., in press.[6] F. Luck, Environmental Catalysis, in: G. Centi et al. (Eds.), EFCE Publishers, Series 112, p. 125.[7] D. Mantzavinos et al., in: V ogelpohl and Geissen (Eds.), in: Proceedings of the Conference on Water Science and Technology, Clausthal-Zellerfeld, Germany, May 1996, J. Int. Assoc. Water Quality, Pergamon, 1997.[8] R. Venkatadri, R.W. Peters, Hazardous Waste Hazardous Mater. 10 (1993) 107.[9] A.M. Braun, E. Oliveros, Water Sci. Tech. 35 (1997) 17.[10] D. Bahnemann et al., Aquatic and surface photochemistry, Am. Chem. Soc. Symp. Ser. (1994) 261.[11] J. Prousek, Chem. Lisy 89 (1995) 11.工业废水回用的接触反应策略摘要：无论从控制污染还是资源恢复的角度，接触反应都是被广泛应用并极具经济效益的。
EGSB反应器英文文献及翻译
Effects of Upflow Liquid Velocity on Performance of Expanded Granular Sludge Bed (EGSB) SystemSeni Karnchanawong and Wachara PhajeeAbstractThe effects of upflow liquid velocity (ULV) on performance of expanded granular sludge bed (EGSB) system were investigated. The EGSB reactor, made from galvanized steel pipe 0.10 m diameter and 5 m height, had been used to treat piggery wastewater, after passing through acidification tank. It consisted of 39.3 l working volume in reaction zone and 122 l working volume in sedimentation zone, at the upper part. The reactor was seeded with anaerobically digested sludge and operated at the ULVs of 4, 8, 12 and 16 m/h, consecutively, corresponding to organic loading rates of 9.6 – 13.0 kg COD/ (m3·d). The average COD concentrations in the influent were 9,601 –13,050 mg/l. The COD removal was not significantly different, i.e.93.0% - 94.0%, except at ULV 12 m/h where SS in the influent was exceptionally high so that VSS washout had occurred, leading to low COD removal. The FCOD and VFA concentrations in the effluent of all experiments were not much different, indicating the same range of treatment performance. The biogas production decreased at higher ULV and ULV of 4 m/h is suggested as design criterion for EGSB system.Keywords—Expanded granular sludge bed system, piggery wastewater, upflow liquid velocityI. INTRODUCTIONAnaerobic digestion (AD) of wastewater can concurrently remove organic matter as well as produce biogas which is the renewable energy. The application of AD as pretreatment step for high chemical oxygen demand (COD) wastewater, preferably higher than 2,000 mg/l, is economically suitable while higher COD also results in higher biogas production [1]. In Thailand, piggery wastewater is increasingly treated by AD technology such as upflow anaerobic sludge blanket (UASB) system,anaerobic pond, channel (plug flow) digester and anaerobic covered lagoon. The biogas is generally used for on-farm electricity generation via induction motor. UASB system is the high-rate wastewater treatment process where wastewater is fed at the bottom and flows upward, passing through layers of anaerobic bacteria with upflow liquid velocity (ULV) 0.5 –1.5 m/h. The bottom layer, referred to as sludge bed, consists of granules with high suspended solids (SS) concentration (~1-5 %) while the upper layer, referred to as sludge blanket, consists of flocculent sludge (SS ~ 0.3-0.5 %). The granule has very high settling velocity as well as treatment efficiency since it consists of layers of bacteria, responsible for various anaerobic digestion steps [2]. The biogas produced is separated by gas-solids separator (GSS) installed at the upper part of reactor while sedimentation zone, above GSS, help SS removal as well as return it back to reactor. The reactions occur under enclosed part and smell is minimal.To improve the efficiency of UASB system, high ULVs (5 -15 m/h) were applied by effluent recycling and resulted in sludge bed expansion throughout the reactor’s height. The high total biomass allowed the improved system, called expanded granular sludge bed (EGSB) system, to accommodate higher organic loading rate (OLR) than UASB system [3]. Since EGSB system is recommended for low SS wastewater, the application on piggery wastewater which has high SS should be firstly verified by laboratory experiment. Moreover, high ULV results in high pumping cost which should be minimized. The objective of this study was to determine the effects of ULV on performance of EGSB system as well as to determinethe suitable ULV for piggery wastewater treatment.II. MATERIAL AND METHODSThe laboratory scale EGSB reactor, made from galvanized steel pipe 0.10 m diameter and 5 m height with digestion volume of 39.3l, was used. The upper part of reactor was sedimentation zone, made from steel plate 0.5 m diameter, 0.6 m height with 0.10 m freeboard and working volume of 122l (Fig. 1). The biogas was measured by gas meter, i.e. revolving boxes with counter. There were 17 sampling ports along reactor’s height at 0.3 m spaci ng. The major sampling ports were at 0.4,1.9, 3.4 and 4.6 m – height. The piggery wastewater was biweekly collected from2 pig farms, firstly Kittiwat Farm and secondly Chomthong Farm. The wastewater was stored in 0 –4 C storage room prior to using. It was daily prepared in 70-l plastic tank equipped with mechanical mixer (EYELA model MDC-MS). The wastewater was pumped by a peristaltic pump (Watson Marlow model 505s) to the complete-mix acidification tank, operated at 8-h hydraulic retention time (HRT). The acidification tank was made from plastic water tank, 0.25 m diameter, 0.30 m height and working volume of 12.8l. The complete -mix condition was maintained by a circulating pump, submersible type (8.5 watts). There was no seeding in acidification reactor. The acidification tank effluent was pumped to EGSB reactor at the rate of 1.6 l/h with expected OLR of 10 kg COD/ (m3·d). The EGSB effluent was stored in a 70-l plastic tank and was recycled by a peristaltic pump (Watson Marlow model 505s) to control ULV at 4, 8, 12 and 16 m/h, consecutively. The EGSB reactor was seeded with anaerobi cally digested sludge from Chiang Mai University wastewater treatment plant at 25,000 mg VSS/l. During start up period, OLR and ULV were stepwise increased to the target values. The water samples were taken 2 times/week and analyzed according to Standard Methods [4]. The experiments had been conducted under ambient temperature, tropical climate at the Department of Environmental Engineering, CMU, Thailand, during May 2003 to May 2004.III. RESULTS AND DISCUSSIONThe piggery wastewater was firstly collected from Kittiwat Farm. During the last period of run 1, this farm which was medium- sized sometimes did not have uniform wastewater flow rate so a bigger farm, Chomthong Farm, was chosen throughout the study. The wastewater characteristics had high fluctuations of COD and SS and the acidification tank helped stabilizing the wastewater concentrations. The performance of acidification tank was rather poor, i.e. COD removal 0 – 5%, VSS removal 2.2 –27.6%. There was no pH adjustment in acidification tank. The influent pH was in neutral range, 6.8 -8.0, while the effluent pH was slightly decreased, 6.8 -7.8. The effluent VFA from acidification were not significantly increased and sometimes slightly decreased, indicating methanogenesis in reactor. It is expected that bacterial enrichment from pig feces plays an important role inVFA degradation. TheFig. 1 Experimental set-upeffluent of acidification tank was further fed to EGSB reactor, initially at OLR 2kg COD/ (m3·d) and ULV 0.5 m/h. The OLRs were stepwise increased to 10 kg COD/( m3·d) at ULV 4 m/h. It took about 3 months to start up the EGSB system before the study period. The system was then operated at various durations as follows; run 1 (ULV 4 m/h) 165 d, run 2 (ULV 8 m/h) 76 d, run 3 (ULV 12 m/h) 56 d, run 4 (ULV 16m/h) 77 d, consecutively. It was found that the influent COD and SS concentrations varied, causing effluent value fluctuations in run 3. During the study, there was no biomass withdrawal from the reactor, except via effluent. The results of COD and SS variations throughout the study are shown in Fig. 2 and 3, respectively.In run 1, the EGSB influent characteristics had average values as follows; COD 9,601 mg/l, Filtered COD (FCOD) 1,514 mg/l, VFA 1,083 mg/l as acetic acid, SS 1,829 mg/l, VSS 1,530 mg/l. In run 2- 4, the average values are as follows; COD 11,355- 13,050 mg/l, Filtered COD (FCOD) 1,720 -2,300 mg/l, VFA 784 - 1,360 mg/l as acetic acid, SS2,930 - 6,590 mg/l, VSS 1,390 - 4,310 mg/l. The EGSB influent had low FCOD:COD ratios, i.e. 0.15 –0.18, and high VSS:SS ratios, i.e. 0.47 –0.87.These indicated that high proportion of organics was in suspended form which was biologically degradable. In run 3, the influent SS was exceptionally high, causing biomass flushing from EGSB reactor. The peak effluent COD was found to be 8,460 mg/l on the 284th day of study period while FCOD did not increase (Fig. 2). The biomass eventually adapted to high ULV and resumed to normal operating condition during the later period of run 3. The steady-state condition in run 3 therefore could not be concluded. Although the OLR in all runs was expected to be uniform at 10 kg COD/ (m3·d), the fluctuations in influent COD concentrations resulted in actual OLRs of 9.6-13.0 kg COD/ (m3·d). The overall performance of EGSB at various ULV is summarized in Table I.Fig. 2 COD variationsFig. 3 SS variationsThe performance of EGSB system in terms of COD removal was in the same ranges (93.0 –94.0%), except in run 3 where effluent suspended biomass (VSS) caused poor COD removal (38.1%). The VFA and FCOD in the effluent, i.e. 94-162 mg/l as acetic acid and 330- 512 mg/l, respectively, were not much different, indicating the relatively stable performance. However, heavy biomass flushing in run 3 showed the higher effluent SS concentrations, as presented in Table I, with 45.0% removal. Once the influent SS decreased and the system adjusted to the applied ULV, the EGSB system resumed to normal operating condition. In run 4 where ULV 16 m/h was applied, the SS removal was found to be 88.0%. It is suggested that EGSB system should be operated at influent SS concentration less than 5,000 mg/l, if high COD andRemark : (1) Average values during steady-state conditions(2) Average values during 284th– 298th day of study periodSS removal (>80%) is needed. The periodic SS withdrawal from reactor is also recommended if low SS in the effluent is required. Based on FCOD, there was nosignificant difference in system performance in terms of organic matter removal at ULV 4 – 16 m/h. The biogas measured had proportionally decreased with increasing ULV. It is expected that biogas volatilization, from excessive dissolving capacity in recycle tank, may be responsible in high effluent recycling condition. The methane (CH4) composition also slightly decreased at higher ULV along with biogas production. The other major gas compositions were nitrogen (17.5 - 27.2%) and carbon dioxide (3.4 - 3.8%). The carbon dioxide content was relatively low as compared to normal UASB reactors [1, 5]. Based on biogas production and recycling cost of effluent, ULV 4 m/h is suggested as design criterion. There was no pH adjustment in EGSB reactor and the system pH, 7.5-8.3, were slightly higher than optimum range for anaerobic process, i.e. 6.5-7.5 [6]. The influent VFA: alkalinity ratios were 0.37-0.54. The average total phosphorus (TP), NH4-N and TKN concentrations in the influent of 4 runs were 21.1-65.2, 113 – 181 and 551 – 634 mg/l, respectively. The COD:N:P ratios in the influent of 4 run were 600:29.4:1.2 –600:33.6:4.2 which were sufficient as compared to the suggested ratio 600:7:1, indicting enough macro nutrients for bacterial cell synthesis[7]. The advantage of EGSB system over UASB system is higher biomass accumulation since higher ULV will expand the sludge bed layer upward through the reactor’s height [3].The vertical solids profile confirmed this assumption, where high concentrations of SS (> 1%) were found along the reactor, as shown in Fig. 4. This solids profile pattern was different from UASB reactor [5], and similar to other EGSB study [8]. However, very high SS concentration (>5%) were found at the bottom layer.The solids distribution and total biomass throughout the study are summarized in Table II.According to Table II, the total biomass did not much differ during the study period. The water samples at the reactor’s height of 0.4, 1.9, 3.4 and 4.6 m were periodically taken. It was found that COD, FCOD and VFA decreased vertically from the bottom to the top of reactor, according to reactions occurred during upflowing. The granules were measured by microscope. The average granule sizes at 0.4 m from bottom were highest (0.33-0.50 mm) while at 3.4 –4.6 m were smaller (0.17-0.20mm).The EGSB granules were much smaller than UASB granules and the flocculent sludge did not present in EGSB reactor as compared to UASB reactor [5]. The high ULV obviously flushed out the floc and low density sludge. The EGSB granule appeared to be round shape and more uniformly distributed than UASB granules [5]. During the study, the scale of struvite (MgNH4PO4 .6H2O, Magnesium Ammonium Phosphate) was found in recycle tubes. The piggery wastewater is favorable for struvite precipitation due to high magnesium, ammonia and phosphorus, as observed in other study. Periodically cleaning of recycling facility is also required.Fig.4 Vertical solids profile of EGSB reactor (run 1, 150th day)IV. CONCLUSIONBased on the results obtained, the following conclusions can be drawn. The performance in terms of organic matter removal of EGSB system at ULV 4 to 16 m/h is not significantly different. The influent SS concentration should be less than 5,000 mg/l to prevent solids wash out. The high ULV results in lower biogas production and ULV 4 m/h is suggested as suitable design criterion.Remark :Data at the beginning and the end of each runACKNOWLEDGMENTThe research support from Faculty of Engineering, Chiang Mai University is gratefully appreciated.REFERENCES[1] G. Lettinga, A.F.M. Van Velson, S.W. Hobma, W. de Zeeuw and A. Klapwijka, ―Use of Upflow Sludge Blanket (UASB) Reactor Concept for Biological Wastewater Treatment Especially of Anaerobic Treatment‖, Biotechnol. Bioeng., vol. 22, 1980, pp. 699-734.[2] F.A. McLoed, S.R. Guiot and J.W. Costerton, ―Layered Structure of Bacteria Aggregates Produced in an Upflow Anaerobic Sludge Bed and Filter Re actor‖, Applied & Env. Micro., vol. 56, 1990, pp. 1598-1607.[3] M.T. Kato, J.A. Field, P. Versteeg and G. Lettinga, ―Feasibility of Expanded Granular Sludge Bed Reactors for the Anaerobic Treatment of Low Strength Soluble Wastewater‖, Biotechnol. Bioeng., vol. 44, 1994, pp. 469-479.[4] APHA, AWW A and WEF, Standards Methods for the Examination of Water and Wastewater,20th Ed., Washington D.C. : American Public Health Association, 1998[5] S. Karnchanawong and K. Teerasoradech, ―Laboratory-scale Study of Soft Drink Wastewater Treatment by UASB Process‖,Proceedings of the 8th International Conference on Anaerobic Digestion, Sendai, 25-29 May 1997, pp. 397-404.[6] P.L. McCarty, ―Anaerobic Waste Treatment Fundamentals, Part I: Chemistry andMicrobiology‖, J. Public Works , vol. 95, 1964, pp. 91-94.[7] R.E. Speece and P.L. McCarty, ―Nutrient Requirements and Biological Solids Accumulation in Anaerobic Digestion‖, Proceeding of 1st International Conference Water Pollution Resource, London : Pergamon Press, 1964[8] R.G. Zoutberg and R. Frankin, ―Anaerobic Treatment of Chemical and Br ewery Wastewater with a New Type of Anaerobic Reactor : the Biobed E GSB Reactor‖, Wat. Sci. Tech., vol. 34(5-6), 1996, pp. 375-381.[9] K.M. Webb and G.E. Ho, ―Struvite (MgNH4PO4.6H2O ) Solubility and its Application to a Piggery Effluent Problem‖, Wat. Sci. Tech ., vol. 26 (9-11),1992, pp. 2229-2232.水力上升流速对膨胀颗粒污泥床（EGSB）性能的影响摘要研究水力上升流速对膨胀颗粒污泥床（EGSB）性能的影响。
污水处理工业废水回用中英文对照外文翻译文献
中英文资料对照外文翻译Catalytic strategies for industrial water re-useAbstractThe use of catalytic processes in pollution abatement and resource recovery is widespread and of significant economic importance [R.J. Farrauto, C.H. Bartholomew, Fundamentals of Industrial Catalytic Processes, Blackie Academic and Professional,1997.]. For water recovery and re-use chemo-catalysis is only just starting to make an impact although bio-catalysis is well established [J.N. Horan, BiologicalWastewater Treatment Systems; Theory and Operation, Chichester, Wiley, 1990.]. This paper will discuss some of the principles behind developing chemo-catalytic processes for water re-use. Within this context oxidative catalytic chemistry has many opportunities to underpin the development of successful processes and many emerging technologies based on this chemistry can be considered .Keywords: COD removal; Catalytic oxidation; Industrial water treatment1.IntroductionIndustrial water re-use in Europe has not yet started on the large scale. However, with potential long term changes in European weather and the need for more water abstraction from boreholes and rivers, the availability of water at low prices will become increasingly rare. As water prices rise there will come a point when technologies that exist now (or are being developed) will make water recycle and re-use a viable commercial operation. As that future approaches, it is worth stating the most important fact about wastewater improvement–avoid it completely if at all possible! It is best to consider water not as a naturally available cheap solvent but rather, difficult to purify, easily contaminated material that if allowed into the environment will permeate all parts of the biosphere. A pollutant is just a material in the wrong place and therefore design your process to keep the material where it should be –contained and safe. Avoidance and then minimisation are the two first steps in looking at any pollutant removal problem. Of course avoidance may not be anoption on an existing plant where any changes may have large consequences for plant items if major flowsheet revision were required. Also avoidance may mean simply transferring the issue from the aqueous phase to the gas phase. There are advantages and disadvantages to both water and gas pollutant abatement. However, it must be remembered that gas phase organic pollutant removal (VOC combustion etc.,) is much more advanced than the equivalent water COD removal and therefore worth consideration [1]. Because these aspects cannot be over-emphasised，a third step would be to visit the first two steps again. Clean-up is expensive, recycle and re-use even if you have a cost effective process is still more capital equipment that will lower your return on assets and make the process less financially attractive. At present the best technology for water recycle is membrane based. This is the only technology that will produce a sufficiently clean permeate for chemical process use. However, the technology cannot be used in isolation and in many (all) cases will require filtration upstream and a technique for handling the downstream retentate containing the pollutants. Thus, hybrid technologies are required that together can handle the all aspects of the water improvement process[6,7,8].Hence the general rules for wastewater improvement are:1. Avoid if possible, consider all possible ways to minimise.2. Keep contaminated streams separate.3. Treat each stream at source for maximum concentration and minimum flow.4. Measure and identify contaminants over complete process cycle. Look for peaks, which will prove costly to manage and attempt to run the process as close to typical values as possible. This paper will consider the industries that are affected by wastewater issues and the technologies that are available to dispose of the retentate which will contain the pollutants from the wastewater effluent. The paper will describe some of the problems to be overcome and how the technologies solve these problems to varying degrees. It will also discuss how the cost driver should influence developers of future technologies.2. The industriesThe process industries that have a significant wastewater effluent are shown in Fig. 1. These process industries can be involved in wastewater treatment in many areas and some illustrations of this are outlined below.Fig. 1. Process industries with wastewater issues.2.1. RefineriesThe process of bringing oil to the refinery will often produce contaminated water. Oil pipelines from offshore rigs are cleaned with water; oil ships ballast with water and the result can be significant water improvement issues.2.2. ChemicalsThe synthesis of intermediate and speciality chemicals often involve the use of a water wash step to remove impurities or wash out residual flammable solvents before drying.2.3. PetrochemicalsEthylene plants need to remove acid gases (CO2, H2S) formed in the manufacture process. This situation can be exacerbated by the need to add sulphur compounds before the pyrolysis stage to improve the process selectivity. Caustic scrubbing is the usual method and this produces a significant water effluent disposal problem.2.4. Pharmaceuticals and agrochemicalsThese industries can have water wash steps in synthesis but in addition they are often formulated with water-based surfactants or wetting agents.2.5. Foods and beveragesClearly use water in processing and COD and BOD issues will be the end result.2.6. Pulp and paperThis industry uses very large quantities of water for processing –aqueous peroxide and enzymes for bleaching in addition to the standard Kraft type processing of the pulp. It is important to realise how much human society contributes to contaminated water and an investigation of the flow rates through municipal treatment plants soon shows the significance of non-process industry derived wastewater.3. The technologiesThe technologies for recalcitrant COD and toxic pollutants in aqueous effluent are shown in Fig. 2. These examples of technologies [2,6,8] available or in development can be categorised according to the general principle underlying the mechanism of action. If in addition the adsorption (absorption) processes are ignored for this catalysis discussion then the categories are:1. Biocatalysis2. Air/oxygen based catalytic (or non-catalytic).3. Chemical oxidation1. Without catalysis using chemical oxidants2. With catalysis using either the generation of _OH or active oxygen transfer. Biocatalysis is an excellent technology for Municipal wastewater treatment providing a very cost-effective route for the removal of organics from water. It is capable of much development via the use of different types of bacteria to increase the overall flexibility of the technology. One issue remains –what to do with all the activated sludge even after mass reduction by de-watering. The quantities involved mean that this is not an easy problem to solve and re-use as a fertilizer can only use so much. The sludge can be toxic via absorption of heavy metals, recalcitrant toxic COD. Inthis case incineration and safe disposal of the ash to acceptable landfill may be required. Air based oxidation [6,7] is very attractive because providing purer grades of oxygen are not required if the oxidant is free. Unfortunately, it is only slightly soluble in water, rather unreactive at low temperatures and, therefore, needs heat and pressure to deliver reasonable rates of reaction. These plants become capital intensive as pressures (from _10 to 100 bar) are used. Therefore, although the running costs maybe low the initial capital outlay on the plant has a very significant effect on the costs of the process. Catalysis improves the rates of reaction and hence lowers the temperature and pressure but is not able to avoid them and hence does not offer a complete solution. The catalysts used are generally Group VIII metals such as cobalt or copper. The leaching of these metals into the aqueous phase is a difficulty that inhibits the general use of heterogeneous catalysts [7]. Chemical oxidation with cheap oxidants has been well practised on integrated chemical plants. The usual example is waste sodium hypochlorite generated in chlor-alkali units that can be utilised to oxidise COD streams from other plants within the complex. Hydrogen peroxide, chlorine dioxide, potassium permanganate are all possible oxidants in this type of process. The choice is primarily determined by which is the cheapest at the point of use. A secondary consideration is how effective is the oxidant. Possibly the most researched catalytic area is the generation and use of _OH as a very active oxidant (advanced oxidation processes) [8]. There are a variety of ways of doing this but the most usual is with photons and a photocatalyst. The photocatalyst is normally TiO2 but other materials with a suitable band gap can be used [9,10]. The processes can be very active however the engineering difficulties of getting light, a catalyst and the effluent efficiently contacted is not easy. In fact the poor efficiency of light usage by the catalyst (either through contacting problems or inherent to the catalyst) make this process only suitable for light from solar sources. Photons derived from electrical power that comes from fossil fuels are not acceptable because the carbon dioxide emission this implies far outweighs and COD abatement. Hydroelectric power (and nuclear power) are possible sources but the basic inefficiency is not being avoided. Hydrogen peroxide and ozone have been used with photocatalysis but they can be used separately or together with catalysts to effect COD oxidation. For ozone there is the problem of the manufacturing route, corona discharge, which is a capital intensive process often limits its application and better route to ozone would be very useful. It is important to note at this point that the oxidants discussed do not have sufficient inherent reactivity to be use without promotion. Thus, catalysis is central to their effective use against both simple organics (often solvents) or complex recalcitrant COD. Hence, the use of Fenton’s catalyst (Fe) for hydrogen peroxide [11]. In terms of catalysis these oxidants together with hypochlorite form a set of materials that can acthas ‘active oxygen transfer (AOT) oxidants’ in the presence of a suitable catalyst. If the AOT oxidant is hypochlorite or hydrogen peroxide then three phase reactions are avoided which greatly simplifies the flowsheet. Cheap, catalytically promoted oxidants with environmentally acceptable products of oxidation that do not require complex chemical engineering and can be produced efficiently would appear to offer one of the best solutions to the general difficulties often observed.3.1. Redox catalysis and active oxygen transferThe mechanism of catalytically promoted oxidation with hydrogen peroxide or sodium hypochlorite cannot be encompassed within one concept, however there are general similarities between the two oxidants that allows one to write a series of reactions for both (Fig. 3) [5]. This type of mechanism could be used to describe a broad range of reactions for either oxidant from catalytic epoxidation to COD oxidation. The inherent usefulness of the reactions is that;1. The reactions take place in a two-phase system.2. High pressure and temperature are not required.3. The catalytic surface can act as an adsorbent of the COD to be oxidised effectively increasing the concentration and hence the rate of oxidation.The simple mechanism shows the selectivity issue with this type of processes. The oxidant can simply be decomposed by the catalyst to oxygen gas – this reaction must be avoided because dioxygen will play no role in COD removal. Its formation is an expensive waste of reagent with oxygen gas ($20/Te) compared to the oxidant ($400–600/Te). To be cost competitive with alternative processes redox catalysis needs excellent selectivity.3.2. Technology mappingThe technologies so far described can be mapped [12] for their applicability with effluent COD concentration (measured as TOC) and effluent flow rate (m3 h-1). The map is shown in Fig. 4. The map outlines the areas where technologies are most effective. The boundaries, although drawn, are in fact fuzzier and should be only used as a guide. Only well into each shape will a technology start to dominate. The underlying cost model behind the map is based on simple assertions – at high COD mass flows only air/oxygen will be able to keep costs down because of the relatively low variable cost of the oxidant. At high COD concentrations and high flows only biological treatment plants have proved themselves viable –of course if done at source recovery becomes an option. At low flows and low COD levels redox AOT catalysis is an important technology – the Synetix Accent 1 process being an example of this type of process (see Fig. 5 for a simplified flowsheet). The catalyst operates under very controlled conditions at pH > 9 and hence metal leaching can be avoided (<5 ppb). The activity and selectivity aspects of the catalyst displayed in Fig. 3 can befurther elaborated to look at the potential surface species. This simple view has been extended by a significant amount of research [3,4,5]. Now the mechanism of such a catalyst can be described in Fig. 6. The key step is to avoid recombination of NiO holes to give peroxy species and this can be contrasted with the hydrogen peroxide situation where the step may be characterized as oxygen vacancy filled. From both recombination will be facilitated by electronic and spatial factors. The range of application of the process is outlined below. From laboratory data some general types of chemical have been found suitable –sulphides, amines, alcohols, ketones, aldehydes, phenols, carboxylic acids, olefins and aromatic hydrocarbons. From industrial trials recalcitrant COD (nonbiodegradable) and sulphur compounds have been successfully demonstrated and a plant oxidising sulphur species has been installed and is operational.4. ConclusionsWastewater treatment processes are in the early stages of development. The key parameters at present are effectiveness and long term reliability. Many processes operating are in this stage, including the redox Accent TM is a trademark of the ICI Group of Companies. catalysis systems. However,once proven, redox catalysis offers many advantages for COD removal from wastewater:1. The low capital cost of installation.2. Simple operation that can be automated.3. Flexible nature of the process – can be easily modified to meet changing demands of legislation.Hence it will be expected to develop into an important technology in wastewater improvement.AcknowledgementsThe author is grateful to Jane Butcher and Keith Kelly of Synetix for discussions on this paper. References[1] R.J. Farrauto, C.H. Bartholomew, Fundamentals of Industrial Catalytic Processes, Blackie Academic and Professional, 1997. F.E. Hancock / Catalysis Today 53 (1999) 3–9 9[2] J.N. Horan, Biological Wastewater Treatment Systems; Theory and Operation, Chichester, Wiley, 1990.[3] F.E. Hancock et al., Catalysis Today 40 (1998) 289.[4] F. King, F.E. Hancock, Catal. Today 27 (1996) 203.[5] J. Hollingworth et al., J. Electron Spectrosc., in press.[6] F. Luck, Environmental Catalysis, in: G. Centi et al. (Eds.), EFCE Publishers, Series 112, p. 125.[7] D. Mantzavinos et al., in: V ogelpohl and Geissen (Eds.), in: Proceedings of the Conference on Water Science and Technology, Clausthal-Zellerfeld, Germany, May 1996, J. Int. Assoc. Water Quality, Pergamon, 1997.[8] R. Venkatadri, R.W. Peters, Hazardous Waste Hazardous Mater. 10 (1993) 107.[9] A.M. Braun, E. Oliveros, Water Sci. Tech. 35 (1997) 17.[10] D. Bahnemann et al., Aquatic and surface photochemistry, Am. Chem. Soc. Symp. Ser. (1994) 261.[11] J. Prousek, Chem. Lisy 89 (1995) 11.工业废水回用的接触反应策略摘要：无论从控制污染还是资源恢复的角度，接触反应都是被广泛应用并极具经济效益的。
环境工程外文文献及翻译-水处理
环境工程外文文献及翻译-水处理摘要水是人类生存不可或缺的资源，但当前全球范围内的水资源短缺和水污染问题越来越严重，给人类带来了严重的环境和健康问题。
环境工程领域的研究者们在水处理方面做出了重要的贡献，下面是关于水处理的外文文献及翻译，希望对读者们有所启发。
文献1：Removal of pharmaceuticals from municipal wastewater using membrane bioreactor technology这篇论文来源于《Water Research》期刊，讨论了利用膜生物反应器技术处理城市污水中的药物问题。
文章指出，生物膜反应器技术可以有效地去除医药废水中的药物，其净化效率高于传统的生物处理方法。
并且，就经济效益而言，膜生物反应器技术比传统的处理方法更为可行。
翻译1：膜生物反应器技术处理城市污水中的医药废水根据《Water Research》期刊报道，膜生物反应器技术是一种有效去除医药废水中药物的方法。
研究表明，这种技术比传统的生物处理方法更为高效，而且在经济上也更加可行。
文献2：Application of a Modified Ultrafiltration Process for Water Reuse in a Municipal Wastewater Treatment Plant这篇论文来源于《Environmental Engineering Science》期刊，介绍了一种改进的超滤技术，在城市污水处理厂中进行水资源回收利用。
论文指出，这种技术能够去除水中的有机物和微生物等污染物，同时还能够保持水质的稳定性。
该技术对于水资源短缺的地区来说十分有用。
翻译2：改进的超滤技术在城市污水处理厂的水资源回收中的应用据《Environmental Engineering Science》期刊报道，一种改进的超滤技术已成功应用于城市污水处理厂中，用于水资源回收利用。
【精品文档】31中英文双语外文文献翻译：利用正向渗透应用于废活性污泥同步增稠、消化和直接脱水的可行性
此文档是毕业设计外文翻译成品（含英文原文+中文翻译），无需调整复杂的格式！下载之后直接可用，方便快捷！本文价格不贵,也就几十块钱！一辈子也就一次的事！外文标题：Feasibility of applying forward osmosis to the simultaneous thickening, digestion, and direct dewatering of waste activated sludge外文作者：Hongtao Zhu , Liqiu Zhang , Xianghua Wen , Xia Huang文献出处:《Bioresource Technology》 , 2018 , 113 (113) :207-213(如觉得年份太老，可改为近2年，毕竟很多毕业生都这样做)英文5098单词， 26874字符(字符就是印刷符)，中文7485汉字。
Feasibility of applying forward osmosis to the simultaneous thickening, digestion, and direct dewatering of waste activated sludgeAbstractThe feasibility of applying forward osmosis (FO) to the simultaneous thickening, digestion, and dewatering of waste activated sludge w as investigated. After 19 days of operation, the total reduction in efficacy of the instantaneous sludge thickening and digestion system in term of mixed liquid suspended solids (MLSS) and mixed liquid volatile suspended solids (MLVSS) was approximated at 63.7% and 80% , respectively, and the MLVSS / MLSS ratio decreased from 80.8% to 67.2%. The MLSS concentration reached 39 g / L from an initial on the day of 7 g / L, indicating a good thickening efficacy. In using FO for sludge dewatering, two major factors were verified, namely, initial sludge depth and draw solution (DS) concentration. A sludge depth of 3 m, w here a dry sludge content of approximately 35% can be achieved in approximately 60 m in, is recommended for future applications. In addition, the present study proved the feasibility of using seawater reverse osmosis concentrate as the DS.Keywords:Forward osmosis, Waste activated sludge, Sludge thickening, Sludge dewatering, Aerobic digestion1. IntroductionLarge quantities of excess high water content are produced in wastewater treatment plants (WWTPs) everyday. To minim the costs of sludge transportation and handling, reduction in sludge volume and through water separation is the most important that needs to be addressed prior to final disposal. Sludge thickening and dewatering are usually practiced for volume and reduction. Normally, sludge thickening is performed to reduce the sludge volume and increase the sludge solid content to obtain a suitably concentrated sludge for the sludge dewatering processes. The com-only sludge thickening processes include gravity thickening, dissolved air flotation thickening, and centrifugal thickening, among others. Although these traditional thickening technologies are ready-to-use and easy to perform, some problems limit their application. For example, the gravity thickening process has the disadvantages of a large footprint, low-thickening efficacy, tendency ofreleasing phosphorus during long-term retention time (SRT), and emission of unpleasant odors (Wang et al., 2008a; Kim et al., 2010). On the other hand, sludge digestion treatment is a standard practice, especially for medium and large-scale WWTPs, and is used as a stabilization step after the thickening process to achieve sludge stabilization, detoxication, and minimization, among others (Wang et al., 2008a). Aside from thickening and digestion, sludge dewatering is about 70%. However, sludge dewatering currently remains the most expensive and most poorly understood wastewater treatment process (Pei et al., 2010, Yuan et al., 2011).To solve the problem s of conventional sludge thickening technologies and shorten the sludge treatment processes (i.e., to lessen the footprint and operational strength), a flatsheet membrane was developed for simultaneous sludge thickening and digestion process (Wang et al., 2008a). This sludge reduction system is actually a membrane bioreactor (MBR), whose advantages include a small footprint, high pollutant removal efficiency, and low cost for the retreatment of the thickened supernate, among others (Judd, 2006). Nevertheless, the relatively high energy requirement, especially from membrane fouling due to high sludge concentration, is the main obstacle for the application of membrane sludge thickening process (Wang et al., 2008b, 2009).In contrast to conventional MBR, several researchers proved that a forward osmotic MBR has better membrane fouling control performance (Cornelissen et al., 2008; Lay et al., 2011; Achilli et al., 2009b). In forward osmosis (FO), such as in the well-known reverse osmosis (RO), water is transported across a semipermeable membrane, which is impermeable to salt and is driven by the difference between the osmotic pressures across the membrane (Cath et al., 2006). Even though osmosis has been recognized and utilized for decades, FO remains a unique and emerging technology (Chung et al., 2010). For the last couple of years, increasing efforts on FO have been exerted due to the availability of more efficient FO membranes (Cornelissen et al., 2008). Present-day FO applications extend from water treatment and food processing to power generation and novel methods of controlling drug release (Wallace et al., 2008; Garcia-Castello and McCutcheon, 2011; Achilli et al., 2009a Sotthivirat et al., 2007). However, in the past 30 years, no studies on the direct use of FO in sludge thickening, digestion, and dewatering were conducted. The only related creative study was performed by Pugsley and Cheng (1981) m ore than 30 years ago. Their study primarily proved the feasibility of applying FO to sludge dewatering. Nevertheless, because of limitations su ch as the lack of efficient FO membranes, m any issues, including the exploration and optimization of the factors affecting FO performance, need further systematic investigation.In FO, the reconcentration of the draw solution (DS), usually com posed of dissolved salts, is a major part of the energy consumption. The current study proposes the utilization of RO concentrates in seawater desalination as the DS. In RO, typical seawater recoveries are between 30% and 50% (Ji et al., 2010; McCutcheon et al., 2005). Discharge of the concentrated brine back into the sea is proven to affect marine fauna and flora (Latorre, 2005) and dam ages benthic organism s due to the coagulants present in the brine (Lattemann and Höpner, 2008). This phenomenon is a critical environmental drawback to seawater desalination RO, which has been set up worldwide. If theconcentrated brine from RO is used as the DS for FO sludge dewatering, the diluted brinecould be directly discharged into the sea without causing any dam age. For the FO sludgedewatering process without DS reconcentration, the energy requirements would bereduced to near zero.In the current study, FO was innovatively applied to simultaneous thickening, digestion,and direct dewatering of raw waste activated sludge from WWTPs. The DS wassynthesized to simulate the concentrated brine of seawater desalination RO (Ji et al., 2010)and was not reconcentrated to minimize the energy demand. The current work aims toconduct a preliminary study on the characteristics (including the digestion efficiency, the reversed salt transport, and the effects of DS concentration on the FO flux) of thesimultaneous thickening and digestion system and on the sludge depth and DSconcentration on FO dewatering performances. Other issues, such as the processmodeling and membrane fouling mechanism s, will be discussed in subsequent studies. 2.Methods2.1. Experimental setup and the FO membraneThe bench-scale FO experimental setups for simultaneous sludge thickening, digestion,and dewatering are shown in Fig. 1. In the sludge thickening and digestion system , thesingle FO membrane module unit consisted of two plexiglass cells that clipped the FOmembrane sheet. The effective membrane surface area of a single unit was approximately0.0133 m 2. Dep ending on the flux requirements, one to three membrane modules can be used for one reactor. The reactor had a cylindrical configuration and a total volume of 1.8 L. Air was supplied through a fine bubble diffuser to supply oxygen to the microorganisms. Two peristaltic pumps, produced by LanGe Company (China), were used for thecirculation of the DS and the sludge. The weight change rates over time of the DS and the diluted DS tanks were recorded via a computer. Based on these data, the flow rates of theDS (i.e., the solution that went into the membrane module) and the diluted DS (i.e., thesolution that went out of the membrane module) were calculated. The real-time membrane flux for a certain DS was calculated from the difference between the two measured flow r ates.The membrane module used in the sludge dewatering system was similar to a ‘‘sandwich’’. The circulation pump pushed the DS through the airtight channel, the bottom layer of the ‘‘sandwich’’. The middle layer was the FO membrane, and the toplayer was a sludge container. Both the DS and the sludge were in direct contact with theFO membrane. The effective membrane area of this module was approximately 0.0035 m 2,and the sludge container had a length of 7 cm , a width of 5 cm , and a maxim um depth of 1 cm . The calculated maxim um sludge volume of the container was 35 m L, whereasthe DS was norm ally m ore than 1000 m L. Therefore, the volume increment of the DSduring the dewatering course was omitted (i.e., the DS concentration used for sludgedewatering was considered as constant).The FO membrane used in the study was supplied by Hydration Technology (HTI, Albany, Oregon, US) and classified as cartridge type. The 50 l m -thick FO membrane was made of cellulose triacetate embedded in a polyester screen mesh (Cath et al., 2006).The HTI membranes, which have been used in a number of studies, are currently viewed as the best available membranes for FO applications (Achilli et al., 2009b; Lay et al., 2011;Holloway et al., 2007; Cornelissen et al.,2008; Xiao et al.,2011). The membrane orientation has a significant effect on the FO flux due to concentration polarization (CP) or membrane fouling. Com pared with the rejection layer facing the DS, the configuration of the rejection layer facing the feed water sh owed a remarkable flux stability against both bulk DS dilution and membrane fouling, although its flux was relatively lower (Tang et al., 2010). In the current study, the configuration of the rejection layer facing the feed water was adopted to prevent a sign ificant flux decline.2.2. DS and activated sludgeAs previously stated, synthetic DS # 1 was prepared to simulate the concentrated brine from RO (30%recovery rate) by dissolving(274 m g/L), and Na2SO4 (4526 m g/L) in(7996 m g/L), NaHCOultrapure water. For future applications, the RO concentrate can be discharged into the sea after dilution, similar to natural seawater. Synthetic DS # 5 was also used in the tests and was prepared to simulate natural seawater by dissolving reagent grade NaCl25,053 m g/L), CaCl2 2H 2O (1608 m g/L), MgCl2 (5597 m g/L), NaH- CO3 (192 m g/L), and Na2SO4 (3168 m g/L) in ultrapure water. Synthetic DSs # 2, # 3, and # 4 were also prepared using the same salts but at proportional concentrations between those of solutions # 1 and # 5. The detailed information is shown in Table 1. The activated sludge was obtained daily from a 60,000 m 3/d MBR facility in a WWTP located in the northern part of Beijing. The sludge samples had a MLSS of 7.3 g/L, a MLVSS of 5.9 g/L, a soluble COD in supernatant of 103 m g/L, and a conductivity of 310 l S/cm .2.3. Analytical methodsAnalyses of the mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), chemical oxygen demand (COD), ammonia nitrogen, and total phosphate were perform ed based on the standard methods proposed by the State Environ- mental Protection Administration of China. The soluble COD (SCOD) samples were prepared using filter papers with a nominal pore size of 0.45 l m . The dissolved oxygen (DO) concentration was determined using a DO meter (Model YSI 58, YSI Research Incorporated, Ohio, US). The mixed liquor viscosity value was obtained using a viscometer (Brookfield, US). The specific oxygen uptake rate was determined based on the standard procedure provided by Zhang (1988). The conductivity of the sludge was monitored using a conductivity probe (Fisher Scientific, Ham pton, NH, US) to calculate the reversed salt transport and the total accumulation of salt in the bioreactor. The equivalent salt (NaCl) concentration was calculated from the conductivity values using a calibration curve. The digestion efficiency was calculated as described in previous studies (Wang et al., 2008a,b, 2009) and is given by where E ct is the cumulate digestion efficiency at day t (%), Q t is the influent sludge flow at day t (m3/d), X it is the influent sludge concentration at day t (g/L), V is the effective volume of the reactor (m3), and X t is the sludge concentration in the reactor at the end of day t (g/L).3. Results and discussion3.1. Variations in the sludge concentration and digestion efficiencyThe DO in the reactor was maintained at around 2.0 mg/L and the hydraulic retention time was about 1 day. During the experi-ments, the fluctuation in the room temperature during daytime was 22–29 LC. The feed sludge volume for each day depended on the average FO membrane flux of that day. The concentration of the feed sludge also varied, depending on the operation of the MBR facility. No sludge was withdrawn during the experiments.The variations in MLSS and MLVSS and, consequently, the MLSS/ MLVSS ratio with the operation time are shown in Fig. 2(a). Both the MLSS and MLVSS concentrations showed increasing trends be-cause of the FO thickening process and the absence of sludge dis-charge. The quantity of pure water extracted from the FO thickening process was calculated and will be discussed in the next section. In the 19 days of operation, the MLSS and MLVSS concentrations quickly increased during the first 7 days and gradually slo-wed down thereafter. At the end of the tests, the MLSS and MLVSS concentrations reached approximately 39 and 27 g/L, respectively. Fig. 2(a)shows the evolution of the MLVSS/MLSS ratio, which continuously decreased from 80.8% to 67.2% throughout the19 days of operation, indicating a continuous sludge reduction via aerobic digestion in the reactor.The total reduction efficiency values of MLSS and MLVSS were approximately 63.7% and 80%, respectively [Fig. 2(b)]. The MLSS reduction efficiency is comparable to the results of Kim et al.(2010),where they achieved an MLSS destruction efficiency rate of 60% using a submerged MBR. However, the obtained MLSS reduction efficiency was lower than that of another submerged MBR sludge thickening system used by Wang et al. (2008a), where the latter achieved an MLSS digestion efficiency of about 80% in 15 days.A possible reason for the difference is that, in their studies, part of the fixed suspended solids permeated through the microfil-tration membrane as colloids, whereas almost no colloid passed through the FO membrane used in the current study. On the other hand, the MLVSS reduction efficiency obtained in the present study is higher than those reported by other researchers using MBR or conventional aerobic digestion process. These results included the following: 73% for a submerged MBR during 15 days (Wang et al., 2008a), 53–64% under a 35-day SRT at an ambient tempera-ture of approximately 20 LC (Bernard and Gray, 2000), 63% under a 16-day SRT with microwave-alkali pretreatment (Chang et al.,2011),39.59% under a 17.5-day SRT (Song et al., 2010),and 50% un-der a 50-day SRT (Novak et al., 2003). The MLSS and MLVSS reduc-tion efficiencies in an aerobic digestion can be enhanced by the addition of digested sludge into undigested sludge, which can serve as the source of the viable cell mass needed for the degrada-tion of organic solids. This is the theory behind the high digestion efficiency achieved in the application of FO to the simultaneous sludge thickening and digestion process, as proposed by Khalili et al. (2000) and supported by Wang et al. (2008b).In the current study, the digested sludge was retained in the reactor and blended with the daily influent (i.e., undigested sludge), resulting in a higher digestion efficiency compared with that of a conventional aerobic digestion process.3.2. Membrane flux decline and reversed salt transport during sludge thickeningThe aerobic digestion and sludge thickening simultaneously occurred. Based on the MLSS concentration of 39 g/L and total MLSS digestion rate of 63.7% on the 19th day, the final calculated MLSS without sludge digestion was approximately 107 g/L. Thus, through the FO sludge thickening system, the activated sludge can be thickened from a water content of 99.3% to approximately 90%, higher than that of most conventional sludge thickening processes.The water flux under different DS concentrations as a function of operating time is shown in Fig. 3(a). The flux evolution curves of DSs # 1, # 2, and # 3 share similar trends, with a rapid decrease at the beginning followed by a smooth development. This phenomenon shows that CP as well as a possible membrane fouling, rapidly occurred within the first several days. Based on the variations in the relative flux over time [Fig. 3(b)], the flux reduction range of each test [Fig. 3(a)] decreased from DS # 1 to DS # 5, which is in accordance with the conclusion that higher DS concentrations result in severe CP (Tang et al., 2010). In other words, DS with low salt concentration exhibited a stable flux even though the resulting flux was relatively low. The initial water flux decreased from DS # 1 to DS # 5, indicating a positive correlation between the water flux and salt concent ration (i.e., osmotic pressure). As the experiment progressed, the water flux under all five conditions was reduced with time, indicating the occurrence of CP, accumulation of reversely transported salt, and/or the development of membrane fouling. A com m on effect of CP and reversed salt transport is the reduction in the apparent osmotic pressure difference (AOPD) across the FO membrane. To determine the amount of flux decline caused by membrane fouling and by the reduction of AOPD across the membrane, similar tests were conducted where the activated sludge was replaced by pure water and all other conditions were kept constant. In these control tests, the flux reduction can be viewed as a result of CP development and reversed salt transport. The flux reduction d ata at the 5th, 10th, and 15th days were re corded for comparison. The difference between the initial and control tests indicated a flux reduction via membrane fouling [Fig. 4(a)]. The extent of membrane fouling significantly decreased with decreasing DS con centration (i.e., from DS # 1 to DS # 5). Membrane fouling slowly increased with operating time from the 5th day onward, exhibiting a different performance com pared with a traditional MBR (Kim et al., 2010). Membrane fouling appeared to have developed qui ckly during the first several days and then slowed afterward, whereas in a conventional MBR, a sharp trans-membrane pressure (TMP) increase after a period of steady performance is com m on. This difference in membrane fouling development maybe due to the driving force variations in osmotic and traditional MBRs. Hydraulic pressure is the driving force in a traditional MBR. As the filtration progresses, the fouling layer becomes increasingly thicker and m ore com pact, leading to a sharp increase in membrane fouling. However, for an osmotic MBR, the driving force is the osmotic pressure difference over the FO membrane. Even though the materials in the solution can still be slightly dragged by the water flow perpendicular to the osmosis membrane, they are probably not attached to the membrane surface as firmly as in a traditional MBR.The flux reductions due to changes in the AOPD are shown in Fig. 4(b). Com pared with membrane fouling, the decrease in AOPD significantly contributed to the flux reduction, indicating a dominant position. AOPD decreased with DS concentration (i.e., from DS # 1 to DS # 5); this result is similar to the fouling trends. For each test, AOPD quickly developed during the first5 days, then slowed in the next 10 days. Obviously, the AOPD development rate gradually decreased with operating time, similar to membrane fouling. FO membranes can reject most ions. However, some of the DS salts were able to pass through the FO membranes into the feed solution; this phenomenon is called salt leakage. This reverse- transported salt from the DS not only causes a reduction in the AOPD butalso exhibits inhibitory or toxic effects on the m icrobial com m unity inside the digestion reactor (Achilli et al., 2009a,b). The variation curves of the equivalent salt (NaCl) concentrations in the reactor are shown in Fig. 5. Although the salt concentration was expected to reach a constant value depending on the operating SRT (Achilli et al., 2009a,b; Xiao et al., 2011), the ‘‘no sludge discharged’’ tests showed that the increasing rate of salt concentration slowed down with operating time. For most of the tests, the salt concentration accumulated very slowly, possibly because of the following: (1) development of CP on both sides, which inhibited the salt mass transfer process; (2) the decreased overall salt concentration difference over the FO membrane due to the gradually increasing salt concentration in the feed sludge; and (3) membrane fouling. If membrane fouling occurred in the form of a gel layer, the m ass transfer resistance would increase and reduce the salt flux. A DS with higher salt concentration (e.g., DS # 1) would probably exhibit a higher salt flux and a higher balance of salt concentration in the feed sludge.3.3. Characteristics of the sludge dewatering FO processIn most presently used sludge dewatering methods, chemical or organic flocculants are used to condition the sludge to facilitate dewatering. These additives increase the cost of the process and tend to make the final disposal of the sludge more difficult. For example, if the dewatered sludge is to be incinerated, the added chemicals may cause harmful effects during the incineration process and to the incinerator itself (Pugsley and Cheng, 1981). There- fore, in the current study, raw activated sludge, even without sludge thickening, was used for the dewatering tests. The possibility of omitting sludge thickening or sludge conditioning in serial studies was also assessed.The sludge dewatering performances of FO under different sludge depths and DS concentrations are shown in Fig. 6. Pugsley and Cheng (1981) reported that sludge depth has a significant effect on dewatering efficiency. In their study, a 0.15%NaCl solution was used to simulate sludge to determine the effects of the sludge depth. The 0.15%NaCl solution does not accurately represent a real sludge because it can m ore easily maintain a constant water concentration com pared with real sludge when water on the FO membrane surface is absorbed through the membrane. If a real activated sludge were used for FO dewatering, the water content profile in the sludge layer would show a decreasing trend toward the FO membrane. The relatively drier sludge layer next to the membrane can be viewed as part of the membrane because it acts as a barrier against the flow of the top-layer water through the membrane. Fig. 6(a) shows that the flux values can be calculated from the slope of the three curves. During a batch sludge-dewatering test, the flux through the FO membrane remained constant at the initial stage an d then gradually decreased regardless of the sludge depth; this result indicates an increasing m ass-transfer resistance. The increased m ass-transfer resistance is believed to be caused bythe ‘‘dewatered sludge’’ layer. Fig. 6(b) shows that the final dry sludge content wasinfluenced by the sludge depth. For the 3 mm depth, the approximately 35% dry sludge content was achieved in approximately 60 m in, whereas for the 5 and 10 m m depths, the dry sludge contents were 30.5% in approximately 90 m in, and 21.5%in approximately 166 m in, respectively. In real applications, a thin sludge layer should be considered for better sludge dewatering performance (i.e., higher dry sludge content and shorter dewatering time).The effects of DS concentration on the membran e flux, final dry sludge content, and corresponding dewatering time are shown in Fig. 6(c) and (d). Not surprisingly, a higher DS concentration means higher flux, higher final dry sludge content, and shorter corresponding dewatering time. However, a significant sludge dewatering performance can also be achieved when seawater is used as the DS. Therefore, the use of seawater RO concentrates as the DS is feasible. In other words, even though DS # 5 showed the least flux, lowest final dry sludge content, and longest corresponding dewatering time, it can still be considered for future projects. As previously conceived, RO concentrates in seawater desalination(simulated by DS # 1) was used as the DS and recirculated until the salt concentration decreased to a level similar to that of regular seawater (simulated by DS # 5); it was then discharged back to the sea. The dewatering ability exhibited by DS # 5 supports this idea. In addition, instead of using recirculation for the utilization of the seawater desalination concentrate as the DS, a dewatering process in the FO membrane belt can be conducted, long enough to ensure that the DS concentration can be reduced to a level similar to that of seawater。
环境工程英文文献附带带翻译
Environmental problems caused by Istanbul subwayexcavation and suggestions for remediationIbrahim OcakAbstract:Many environmental problems caused by subway excavations have inevitably become an important point in city life. These problems can be categorized as transporting and stocking of excavated material, traffic jams, noise, vibrations, piles of dust mud and lack of supplies. Although these problems cause many difficulties, the most pressing for a big city like Istanbul is excavation, since other li sted difficulties result from it. Moreover, these problems are environmentally and regionally restricted to the period over which construction projects are underway and disappear when construction is finished. Currently, in Istanbul, there are nine subway construction projects in operation, covering approximately 73 km in length; over 200 km to be constructed in the near future. The amount of material excavated from ongoing construction projects covers approximately 12 million m3. In this study, problems—primarily, the problem with excavation waste (EW)—caused by subway excavation are analyzed and suggestions for remediation are offered.Keywords: Environmental problems Subway excavation Waste managementIntroductionNowadays, cities are spreading over larger areas with increasing demand on extending transport facilities. Thus, all over the world, especially in cities where the population exceeds 300,000–400,000 people, railway-based means of transportation is being accepted as the ultimate solution. Therefore, large investments in subway and light rail construction are required. The construction of stated systems requires surface excavations, cut and cover tunnel excavations, bored tunnel excavations, redirection of infrastructures and tunnel construction projects. These elements disturb the environment and affect everyday life of citizens in terms of running water, natural gas, sewer systems and telephone lines.One reason why metro excavations affect the environment is the huge amount of excavated material produced. Moreover, a large amount of this excavated material is composed of muddy and bentonite material. Storing excavated material then becomes crucial. A considerable amount of pressure has been placed on officials to store and recycle any kind of excavated material. Waste management has become a branch of study by itself. Many studies have been carried out on the destruction, recycling and storing of solid, (Vlachos 1975; Huang et al. 2001; Winkler 2005; Huang et al. 2006; Khan et al. 1987; Boadi and Kuitunen 2003; Staudt and Schroll 1999; Wang 2001; Okuda and Thomson 2007; Yang and Innes 2007), organic (Edwards et al. 1998, Jackson 2006; Debra et al. 1991; Akhtar and Mahmood 1996; Bruun et al. 2006; Minh et al. 2006), plastic (Idris et al. 2004; Karani and Stan Jewasikiewitz 2007; Ali et al. 2004; Nishino et al. 2003; Vasile et al.2006; Kato et al. 2003; Kasakura et al. 1999; Hayashi et al. 2000), toxic (Rodgers et al. 1996; Bell and Wilson 1988; Chen et al. 1997; Sullivan and Yelton 1988), oily(Ahumada et al. 2004; Al-Masri and Suman 2003), farming(Garnier et al. 1998; Mohanty 2001) and radioactive materials(Rocco and Zucchetti 1997; Walker et al. 2001; Adamov et al. 1992; Krinitsyn et al. 2003).Today, traditional materials, including sand, stone, gravel, cement, brick and tiles are being used as major building components in the construction sector. All of these materials have been produced from existing natural resources and may have intrinsic distinctions that damage the environment due to their continuous exploitation. In addition, the cost of construction materials is incrementally increasing. In Turkey, the prices of construction materials have increased over the last few years. Therefore, it is very important to use excavation and demolition wastes (DW) in construction operations to limit the environmental impact and excessive increase of raw material prices. Recycling ratios for excavation waste (EW) and DW of some countries are in shown Table 1 (Hendriks and Pietersen 2000). The recycling ratio for Turkey is 10%. Every year, 14 million tons of waste materials are generated in Istanbul. These waste materials consist of 7.6 million tons EW, 1.6 million tons organic materials and 2.7 million tons DW (IMM 2007). Approximately, 3.7 million tons of municipal wastes are produced in Istanbul every year. However, the recycling rate is approximately equal to only 7%. This rate will increase to 27%, when the construction of the plant is completed. Medical wastes are another problem, with over 9,000 tons dumped every year. Medical wastes are disposed by burning. Distributions of municipal wastes are given in Fig. 1Country Concentration of CWin total waste (in%)CW and DW recycled (in%)Japan36 65Australia44 51Germany19 50Finland14 40United Kingdom over 50 40USA29 25France25 25Spain70 17Italy30 10Brazil15 8Table 1 C omparison of a few countries’ construction waste concentrationFig. 1 Current status of municipal waste distribution in IstanbulIn this study, environmental problems in Istanbul, such as EW resulting from tunnelling operations, DW resulting from building demolition and home wastes, are evaluated. Resources of EW, material properties and alternatives of possible usage are also evaluated.Railway system studiesThree preliminary studies concerning transportation in Istanbul were conducted in 1985, 1987 and 1997. A fourth study is currently being conducted. The Istanbul Transportation Main Plan states that railway systems must constitute the main facet of Istanbul’s transportation net-work (IMM 2005). In addition to existing lines, within the scope of the Marmaray Project, 36 km of metro, 96 km of light rail, and 7 km of tram, with a total of 205 km of new railway lines, must be constructed. Consequently, the total length of railway line will exceed 250 km.Environmental problems caused by subway excavationsTransporting and storing excavated materialAlmost all land in Istanbul is inhabited. Therefore, it is of utmost importance to store and recycle excavated material obtained either from metro excavations or other construction activities, causing minimal damage and disturbance to the city. The collection, temporary storage, recycling, reuse, transportation and destruction of excavated material and construction waste are controlled by environmental law number 2872. According to this law, it is essential that:1. Waste must be reduced at its source.2. Management must take necessary precautions to reduce the harmful effects of waste.3. Excavated material must be recycled and reused, especially within the construction infrastructure.4. Excavated material and construction waste must not be mixed.5. Waste must be separated from its source and subjected to “selective destruction” in order to form a sound system for recycling and destruction.6. Producers of excavated material or construction waste must provide required funds to destroy waste.According to environmental laws, municipalities are responsible for finding areas within their province limits to excavate and operate these systems. Both the Istanbul Metropolitan Municipality Environmental Protection and Waste Recycling Company are the foundations that actively carryout all operations regarding excavated material.Since dumping areas have limited space, they are quickly filled, without a ny available plausible solution for remediation. In addition, existing dumping areas are far away from metro excavation areas. This means that loaded trucks are competing with city traffic, causing traffic congestion with their low speed and pollutants dropping off their wheels or bodies. Furthermore, this results in a loss of money and labour.The approximate amount of excavated material from ongoing railway excavation will be equal to 12 million m3. All tunnels have been excavated with new Austrian tunnelling method (NATM), earth pressure balance method (EPBM), tunnel boring machine (TBM), and cut and cover method.Existing dumping areas in Istanbul are listed in Table 2. It can be seen that existing dumping areas can only accommodate material excavated from the metro construction. Another important matter according to Table 2 is that 93% of existing dumping areas are on the European side of Istanbul, with 88% of them in Kemerburgaz. Thus, all excavated material on the Anatolian side must cross over European site every day for a distance of approximately 150 km. Every day, on average, 3,000 trucks carry various types of excavated material to Kemerburgaz from other parts of Istanbul. This leads to a waste of time and increased environmental pollution.Name of firm Dumping Capacity (m3)%Total of European side13,984,158 93.3 Total of Anatolian side (six companies)Various 1,011,486 6.7Table 2 Existing dumping areas in IstanbulAnother problem related to excavation is that the materials, obtained from EPBM machines and muddy areas, cannot be directly sent to dumping facilities. They have to be kept in suitable places, so that water can be drained off from the materialand then sent to proper facilities. However, this causes muddy material to drop from trucks, causing increased litter in cities.Traffic jamSince most of the railway constructions are carried out in the most densely populated areas, city traffic must be cl osed and redirected during the construction. In most cases, an entire area must be closed for traffic. For example, Uskudar square is now closed due to the Marmaray project and most bus stops and piers have been moved to other locations.With cut and cover constructions, the case becomes even more complicated. In this case, an entire route is closed to traffic because cut and cover tunnels are constructed across streets. In order to ensure that machine operation and construction can continue uninterrupted and to minimize the risk of accidents to the people living around the construction zone, streets are either totally closed to traffic or traffic is redirected. This causes long-term difficulties. For example, shop owners on closed streets have difficulties re aching their shops, stocking and transporting their goods and retaining customers.Noise and vibrationFor metro excavations, a lot of different machines are used. These machines seriously disturb the environment with their noise and vibrations. In some regions, excavation may be as close as 5–6 m away from inhabited apartment blocks. In such cases, people are disturbed as excavation may take a significant p eriod of time to be completed.Drilling–blasting may be needed in conventional methods for drilling through hard rock. In this case, no matter how controlled the blasting is, people who are living in the area experience both noise and vibrations. Some become scared, thinking that an earthquake is happening. In blasting areas, the intensity of vibrations is measured. In order to keep them within accepted limits, delayed capsules are used.In order to minimize vibration and noise caused by machines and to reduce the effects of blasting, working areas are surrounded by fences. Super ficial blasting shaft rims are covered with a large canvas and fences are covered with wet broadcloths. However, these precautions can only reduce negative effects; they cannot totally eliminate them.The formation of dust and mudDepending on the season, both dust and mud disturb the environment. During removal of excavated material, especially muddy material, trucks may pollute the environment despite all precautions taken. Mud that forms around the excavation area may slide down the slope and cover the ground. In this case although roads are frequently cleaned, the environment is still disturbed. Trucks, which travel from dumping areas to areas that are mud dy cannot enter traffic until their wheels and bodies are washed. However, this cannot prevent the truck wheel from dropping mud on the roads while on move.Interrupted utilitiesInterrupted utilities are also one of the most crucial problems facing citizens during excavation projects due to the fact that telephone, natural gas, electricity, water, and infrastructure lines must be cut off and moved to other areas. During the transfer of these lines, services may remain unavailable for some time. Some institutions will not allow others to do this and carry out operations themselves. With so many providers conducting individual moves, services may be interrupted for an extended term of time.Damage to neighbouring buildingsMetro excavations cause deformations around the excavation area. These deformations are continuously checked and efforts are made to keep them under control. However, some deformations may become extensive; including cracks or even collapses of neighbouring buildings. Every metro tunnel excavation in Istanbul causes problems as mentioned earlier. These kinds of problems are more frequent in shallow tunnels. In such cases, although people’s financial losses are compen sated, their overall livelihood and way of life is compromised. For example, in a landslip during the first stage of the Istanbul Metro excavation, five people died. Obviously, no amount of money can compensate the death of a person.Suggestions for remedying environmental problemsEnvironmental problems that arise during tunnel excavations include traffic jams, noise, vibrations, dust, mud and deformation of surrounding buildings. Some possible solutions are recommended as listed below:• In big cities, railway systems are crucial to city transportation. However, a tram should not be considered as a viable railway system due to its low transportation capacity (approximately 1/3 of the metro). At the same time, a tram uses the same route as wheeled transportation devices. Therefore, trams occupy the same space as regular traffic a nd do not offer substantial advantages.• The most crucial problem facing metro excavations is not providing railway lines in a timely manner. Proof of this exists in big cities, including London, Paris, Moscow or Berlin, where metro lines of over 500 km exist. However, in Istanbul, there are only 8 km of metro line. Had the metro been built earlier when the city was not overcrowded, many problems facing the city would not currently exist. Now, officials must do their best to reduce troubles that future generations are likely to face.• Any kind of railway construction carried out above the ground causes serious problems to people living in the area. In addition, these kinds of construction cause both noise and litter. All railway lines are constructed completely underground in many parts of the world. This has two advantages; first, since excavation is carried out underground, it causes minimal interruption in utilities and provides a more comfortable area to work. Thus, the environment is exposed to very little damage because all operations are carried out underground.• Before beginning metro excavations, the route must be carefully examined for weaknesses in infrastructures and existing historical buildings. Otherwise, these elements cause problems, including interruptions in excavation when work must stop until the environment is stabilized. An example of this is that during the second stage of the Taksim–Yenikapi route of the Istanbul Metro, the construction of the Halic Bridge could not be started due to historical ramparts.• A lack of coordination among related institutions providing utility services is a major problem. Therefore, founding of an institution that strictly deals with relocating natural gas lines, telephone lines, sewer systems, and electricity will definitely accelerate the transfer of energy lines and avert accidents and inconveniences caused by this lack of coordination.•In order to increase benefits of railway systems both in constr uction and operational stages, projects must be continuously revised from time to time. This is the main problem facing Istanbul metro excavations. It has taken 110 years to restart metro projects in Istanbul, with the last project, the opening of the Karakoy tunnel, established in 1876 (Ocak 2004).From this time onward, initiated projects must have been stable and continuous. In 1935, 314,000 passengers were travelling daily. In the 1950s, the total length of tram lines reached 130 km (Kayserilioglu 2001). However, as the trolleybus was introduced in 1961, all tram lines on the European side, and in 1966, all lines on the Anatolian side were removed in order to make way for private vehicles (Kayserilioglu 2001).Results and discussionTBM and classic tunnel construction methods are widely used in Istanbul for different purposes, like metro, sewerage and water tunnels. Waste from rock is rarely used as construct ion material as the suitability of the material for this purpose is not well examined. However, it is believed that the muck may be used for some applications. If this suitability is realized, cost savings may be significant for tunnel construction, where the use of aggregate is a common requirement. A review of standard construction aggregate specifications indicates th at hard rock TBM waste would be suitable for several construction applications, including pavement and structural concrete (Gertsch et al. 2000). Size distributions of waste materials produced by tunnel boring machines are less (up to 125mm) than the waste materials produced by using classical construction methods. Muck size distribution is uniform, generally larger (up to 30–40 cm) and can be changed to meet a wide range of classical construction methods, making the reuse of waste more common. The waste product is used as construction materials. Fifty -seven percent of EW generated during tunnel excavations result from classical tunnel construction, 33.5% from TBM, while the remaining percentage stems from EPBM and slurry TBM. Different from TBM waste materials generated by EPB and slurry, TBM include mud and chemical materials.The annual quantity of EW generated in Istanbul is approximately 7.6 million tons. 13.8% of this total is clay and fill. The rest is composed of rock. Rock material can be properly used in roadway structures, fillings, road slopes, for erosion controland as a sub-base material, as long as it conforms to local standards (TS706, TS1114). Sand and clay have properties appropriate for use as raw materials for industrial use, depending on local standards. More studies should be completed to determine other potential uses for this material. Only 10% of rock material generated during tunnel excavation can be evaluated. A large percentage of soil material, nearly 70,000 m3, can be recycled.Generally, for any subway construction project, plans for recycling waste materials should be implemented prior to work commencement. These plans should identify which types of waste will be generated and the methods that will be used to handle, recycle and dispose these materials. Additionally, areas for temporary accumulation or storage should be clearly designated. A waste management plan directs construction activities towards an environmentally friendly process by reducing the amount of used and unused waste materials. Environmental andecon omic advantages occurring when waste materials are diverted from landfills include the following (Batayneh et al. 2007):1. The conservation of raw materials2. A reduction in the cost of waste disposal3. An efficient use of materials.EW materials mu st be kept clean and separate in order for them to be efficiently used or recycled. Storage methods should be investigated to prevent material from being lost due to mishandling. In addition, orders for materials should be placed just before work commences. To complete a waste management plan, an estimation of the amount and type of usable and unusable EW materials expected to be generated should be developed. Listing all expected quantities of each type of waste will give an indication of what type of man agement activities are appropriate for each specific waste material. At each stage of excavation, specific ways to reduce, reuse or recycle produced EW should be implement ed. The flow chart in Fig. 2 includes suggestions for an EW management plan.This paper focuses on EW produced by metro tunnel excavation through hard rock and soil. TBM and classical tunnelling wastes can be successfully used in many construction and speciality applications, including aggregates, erosion control, roadway structures, fill, sub-base material and road slopes. In order to minimize negative effects caused by excavated material both on the environment and on people, it must be reduced at its source. Including forcible decrees through the acceptance of environmental laws would also be useful. Soil and clay material, excavated through the use of EPBM machines, must be reused. It is possible to separate clay and sand, making its reuse possible and minimizing harmful environmental effect.Waste and recycling management plans should be developed for any construction project prior to commencement in order to sustain environmental, economic, and social development principles. Waste management is a critical issue facing the construction industry in Istanbul as the industry is one of the biggest generators of pollution. During different excavation projects, construction, demolitions and domestic activities, Istanbul produces about 14 million tons of solid waste each year, posing major environmental and ecological problems, including the need for a large area of land to be used as storage and disposal facilities. This wasteconsists of EW (7.6 million tons), DW (2.7 million tons) and municipal waste (3.7 million tons). The recycling rate of municipal waste is only 7%. The recycling rate of EW and DW is below 10% (IMM 2007).Fig. 2 Flow chart for EW management伊斯坦布尔地铁开挖引起的环境问题及补救建议摘要：许多地铁开挖引起的环境问题不可避免地成为城市生活的重要部分。
毕业设计论文化学系毕业论文外文文献翻译中英文
毕业设计论文化学系毕业论文外文文献翻译中英文英文文献及翻译A chemical compound that is contained in the hands of the problemsfor exampleCatalytic asymmetric carbon-carbon bond formation is one of the most active research areas in organic synthesis In this field the application of chiral ligands in enantioselective addition of diethylzinc to aldehydes has attracted much attention lots of ligands such as chiral amino alcohols amino thiols piperazines quaternary ammonium salts 12-diols oxazaborolidines and transition metal complex with chiral ligands have been empolyed in the asymmetric addition of diethylzinc to aldehydes In this dissertation we report some new chiral ligands and their application in enantioselective addition of diethylzinc to aldehydes1 Synthesis and application of chiral ligands containing sulfur atomSeveral a-hydroxy acids were prepared using the literature method with modifications from the corresponding amino acids valine leucine and phenylalanine Improved yields were obtained by slowly simultaneous addition of three fold excess of sodium nitrite and 1 tnolL H2SO4 In the preparation of a-hydroxy acid methyl esters from a-hydroxy acids following the procedure described by Vigneron a low yield 45 was obtained It was found that much better results yield 82 couldbe obtained by esterifying a-hydroxy acids with methanol-thionyl chlorideThe first attempt to convert S -2-hydroxy-3-methylbutanoic acid methyl ester to the corresponding R-11-diphenyl-2-mercapto-3-methyl-l-butanol is as the following S-2-Hydroxy-3-methylbutanoic acid methyl ester was treated with excess of phenylmagnesium bromide to give S -11-diphenyl-3-methyl-12-butanediol which was then mesylated to obtain S -11-diphenyl-3-methyl-2-methanesulfonyloxy -l-butanol Unfortunately conversion of S-11-diphenyl-3-methyl-2- methanesulfonyloxy -l-butanol to the corresponding thioester by reacting with potassium thioacetate under Sn2 reaction conditions can be achieved neither in DMF at 20-60 nor in refluxing toluene in the presence of 18-crown-6 as catalyst When S -1ll-diphenyl-3-methyl-2- methane sulfonyloxy -l-butanol was refluxed with thioacetic acid in pyridine an optical active epoxide R-22-diphenyl -3-isopropyloxirane was obtained Then we tried to convert S -11-diphenyl-3-methyl-l2-butanediol to the thioester by reacting with PPh3 DEAD and thioacetic acid the Mitsunobu reaction but we failed either probably due to the steric hindrance around the reaction centerThe actually successful synthesis is as described below a-hydroxy acid methyl esters was mesylated and treated with KSCOCH3 in DMF to give thioester this was than treated with phenyl magnesium bromide to gave the target compound B-mercaptoalcohols The enantiomeric excesses ofp-mercaptoalcohols can be determined by 1H NMR as their S -mandeloyl derivatives S -2-amino-3-phenylpropane-l-thiol hydrochloride was synthesized from L-Phenylalanine L-Phenylalanine was reduced to the amino alcohol S -2-amino-3-phenylpropanol Protection of the amino group using tert-butyl pyrocarbonate gave S -2-tert-butoxycarbonylamino-3-phenylpropane-l-ol which was then O-mesylated to give S -2-tert-butoxycarbonylamino-3-phenylpropyl methanesulfonate The mesylate was treated with potassium thioacetate in DMF to give l-acetylthio-2-tert-butoxycarbonylamino-3-phenylpropane The acetyl group was then removed by treating with ammonia in alcohol to gave S -2-tert-butoxycarbonylamino-3-phenyl-propane-l-thiol which was then deprotected with hydrochloric acid to give the desired S-2-amino-3-phenylpropane-1-thiol hydrochlorideThe enantioselective addition of diethylzinc to aldehydes promoted by these sulfur containing chiral ligands produce secondary alcohols in 65-79 Synthesis and application of chiral aminophenolsThree substituted prolinols were prepared from the naturally-occurring L-proline using reported method with modifications And the chiral aminophenols were obtained by heating these prolinols with excess of salicylaldehyde in benzene at refluxThe results of enantioselective adBelow us an illustration forexampleN-Heterocyclic carbenes and L-Azetidine-2-carboxylicacidN-Heterocyclic carbenesN-Heterocyclic carbenes have becomeuniversal ligands in organometallic and inorganic coordination chemistry They not only bind to any transition metal with low or high oxidation states but also to main group elements such as beryllium sulfur and iodine Because of their specific coordination chemistry N-heterocyclic carbenes both stabilize and activate metal centers in quite different key catalytic steps of organic syntheses for example C-H activation C-C C-H C-O and C-N bond formation There is now ample evidence that in the new generation of organometallic catalysts the established ligand class of organophosphanes will be supplemented and in part replaced byN-heterocyclic carbenes Over the past few years this chemistry has become the field of vivid scientific competition and yielded previously unexpected successes in key areas of homogeneous catalysis From the work in numerous academic laboratories and in industry a revolutionary turningpoint in oraganometallic catalysis is emergingIn this thesis Palladium Ⅱ acetate and NN"-bis- 26-diisopropylphenyl dihydro- imidazolium chloride 1 2 mol were used to catalyze the carbonylative coupling of aryl diazonium tetrafluoroborate salts and aryl boronic acids to form aryl ketones Optimal conditions include carbon monoxide 1 atm in 14-dioxane at 100℃ for 5 h Yields for unsymmetrical aryl ketones ranged from 76 to 90 for isolated materials with only minor amounts of biaryl coupling product observed 2-12 THF as solvent gave mixtures of products 14-Dioxane proved to be the superior solvent giving higher yieldsof ketone product together with less biphenyl formation At room temperature and at 0℃ with 1 atm CO biphenyl became the major product Electron-rich diazonium ion substrates gave a reduced yield with increased production of biaryl product Electron-deficient diazonium ions were even better forming ketones in higher yields with less biaryl by-product formed 2-Naphthyldiazonium salt also proved to be an effective substrate givingketones in the excellent range Base on above palladium NHC catalysts aryl diazonium tetrafluoroborates have been coupled with arylboron compounds carbon monoxide and ammonia to give aryl amides in high yields A saturated yV-heterocyclic carbene NHC ligand H2lPr 1 was used with palladium II acetate to give the active catalyst The optimal conditions with 2mol palladium-NHC catalyst were applied with various organoboron compounds and three aryl diazonium tetrafluoroborates to give numerous aryl amides in high yield using pressurized CO in a THF solution saturated with ammonia Factors that affect the distribution of the reaction products have been identified and a mechanism is proposed for this novel four-component coupling reactionNHC-metal complexes are commonly formed from an imidazolium salt using strong base Deprotonation occurs at C2 to give a stable carbene that adds to form a a-complex with the metal Crystals were obtained from the reaction of imidazolium chloride with sodium t- butoxide Nal and palladium II acetate giving a dimeric palladium II iodide NHC complex The structure adopts a flat 4-memberedring u2 -bridged arrangement as seen in a related dehydro NHC complex formed with base We were pleased to find that chloride treated with palladium II acetate without adding base or halide in THF also produced suitable crystals for X-ray anaysis In contrast to the diiodide the palladium-carbenes are now twisted out of plane adopting a non-planar 4-ring core The borylation of aryldiazonium tetrafluoroborates with bis pinacolatoborane was optimized using various NHC ligand complexes formed in situ without adding base NN"-Bis 26-diisopropylphenyl-45-dihydroimidazolium 1 used with palladium acetate in THF proved optimal giving borylated product in 79 isolated yield without forming of bi-aryl side product With K2CO3 and ligand 1 a significant amount of biaryl product 24 was again seen The characterization of the palladium chloride complex by X-ray chrastallography deL-Azetidine-2-carboxylic acidL-Azetidine-2-carboxylic acid also named S -Azetidine-2-carboxylic acid commonly named L-Aze was first isolated in 1955 by Fowden from Convallaria majalis and was the first known example of naturally occurring azetidine As a constrained amino acid S -Azetidine-2-carboxylic acid has found many applications in the modification of peptides conformations and in the area of asymmetric synthesis which include its use in the asymmetric reduction of ketones Michael additions cyclopropanations and Diels-Alder reactions In this dissertation five ways for synthesize S-Azetidine-2-carboxylic acid were studied After comparing all methods theway using L-Aspartic acid as original material for synthesize S-Azetidine-2-carboxylic acid was considered more feasible All mechanisms of the way"s reaction have also been studied At last the application and foreground of S -Azetidine-2-carboxylic acid were viewed The structures of the synthetic products were characterized by ThermalGravity-Differential Thermal Analysis TG-DTA Infrared Spectroscopy IR Mass Spectra MS and 1H Nuclear Magnetic Resonance 1H-NMR Results showed that the structures and performances of the products conformed to the anticipation the yield of each reaction was more than 70 These can conclude that the way using L-Aspartie acid as original material for synthesize S -Azetidine-2-carboxylic acid is practical and effective杂环化合物生成中包含手性等问题如催化形成不对称碳碳键在有机合成中是一个非常活跃的领域在这个领域中利用手性配体诱导的二乙基锌和醛的不对称加成引起化学家的广泛关注许多手性配体如手性氨基醇手性氨基硫醇手性哌嗪手性四季铵盐手性二醇手性恶唑硼烷和过渡金属与手性配体的配合物等被应用于二乙基锌对醛的不对称加成中在本论文中我们报道了一些新型的手性配体的合成及它们应用于二乙基锌对醛的不对称加成的结果1含硫手性配体的合成和应用首先从氨基酸缬氨酸亮氨酸苯丙氨酸出发按照文献合成α-羟基酸并发现用三倍量的亚硝酸钠和稀硫酸同时滴加进行反应能适当提高反应的产率而根据Vigneron等人报道的的方法用浓盐酸催化从α-羟基酸合成α-羟基酸甲酯时只能获得较低的产率改用甲醇-二氯亚砜的酯化方法时能提高该步骤的产率从 S -3-甲基-2-羟基丁酸甲酯合成 R -3-甲基-11-二苯基-2-巯基-1-丁醇经过了以下的尝试 S -3-甲基-2-羟基丁酸甲酯和过量的格氏试剂反应得到 S -3-甲基-11-二苯基-12-丁二醇进行甲磺酰化时位阻较小的羟基被磺酰化生成 S -3-甲基-11-二苯基-2- 甲磺酰氧基 -1-丁醇但无论将 S -3-甲基-11-二苯基-2- 甲磺酰氧基 -1-丁醇和硫代乙酸钾在DMF中反应 20～60℃还是在甲苯中加入18-冠-6作为催化剂加热回流都不能得到目标产物当其与硫代乙酸在吡啶中回流时得到的不是目标产物而是手性环氧化合物 R -3-异丙基-22-二苯基氧杂环丙烷从化合物 S -3-甲基-11-二苯基-12-丁二醇通过Mitsunobu反应合成硫代酯也未获得成功这可能是由于在反应中心处的位阻较大造成的几奥斯塑手村犯体的合成裁其在不对称奋成中肠左用摘要成功合成疏基醇的合成路是将a-轻基酸甲酷甲磺酞化得到相应的磺酞化产物并进行与硫代乙酸钾的亲核取代反应得到硫酷进行格氏反应后得到目标分子p一疏基醇用p一疏基醇与 R 义一一甲氧基苯乙酞氯生成的非对映体经H侧NM吸测试其甲氧基峰面积的积分求得其ee值 3一苯基一氨基丙硫醇盐酸盐从苯丙氨酸合成斗3一苯基一氨基丙醇由L一苯丙氨酸还原制备氨基保护后得到习一3一苯基一2一叔丁氧拨基氨基一1一丙醇甲磺酞化后得到习一3一苯基一2一叔丁氧拨基氨基一1一丙醇甲磺酸酷用硫代乙酸钾取代后得匀一3-苯基一2一叔丁氧拨基氨基一1一丙硫醇乙酸酷氨解得习一3一苯基一2一叔丁氧拨基氨基一1一丙硫醇用盐酸脱保护后得到目标产物扔3一苯基屯一氨基丙硫醇盐酸盐手性含硫配体诱导下的二乙基锌与醛的加成所得产物的产率为65一79值为O井92手性氨基酚的合成和应用首先从天然的L一脯氨酸从文献报道的步骤合成了三种脯氨醇这些手性氨基醇与水杨醛在苯中回流反应得到手性氨基酚手性氨基酚配体诱导下的二乙基锌与醛的加成所得产物的产率为45一98值为0一90手性二茂铁甲基氨基醇的合成和应用首先从天然氨基酸绿氨酸亮氨酸苯丙氨酸和脯氨酸合成相应的氨基醇这些氨基醇与二茂铁甲醛反应生成的NO一缩醛经硼氢化钠还原得到手性二茂铁甲基氨基醇手性二茂铁甲基氨基醇配体诱导下的二乙基锌与醛的加成所得产物的产率为66一97下面我们举例说明一下例如含氮杂环卡宾和L-氮杂环丁烷-2-羧酸含氮杂环卡宾含氮杂环卡宾已广泛应用于有机金属化学和无机配合物化学领域中它们不仅可以很好地与任何氧化态的过渡金属络合还可以与主族元素铍硫等形成配合物由于含氮杂环卡宾不但使金属中心稳定而且还可以活化此金属中心使其在有机合成中例如C-H键的活化C-CC-HC-O和C-N键形成反应中有着十分重要的催化效能现有的证据充分表明在新一代有机金属催化剂中含氮杂环卡宾不但对有机膦类配体有良好的互补作用而且在有些方面取代有机膦配体成为主角近年来含氮杂环卡宾及其配合物已成为非常活跃的研究领域在均相催化这一重要学科中取得了难以想象的成功所以含氮杂环卡宾在均相有机金属催化领域的研究工作很有必要深入地进行下去本文研究了乙酸钯和NN双 26-二异丙基苯基 -45-二氢咪唑氯化物1作为催化剂催化芳基四氟硼酸重氮盐与芳基硼酸的羰基化反应合成了一系列二芳基酮并对反应条件进行了优化使反应在常温常压下进行一个大气压的一氧化碳14-二氧杂环己烷作溶剂100℃反应5h 不同芳基酮的收率达7690仅有微量的联芳烃付产物 212 反应选择性良好当采用四氢呋喃或甲苯作溶剂时得到含较多副产物的混合物由此可以证明14-二氧杂环己烷是该反应最适宜的溶剂在室温或0℃与一个大气压的一氧化碳反应联芳烃变成主产物含供电子取代基的芳基重氮盐常常给出较低收率的二芳基酮而含吸电子取代基的芳基重氮盐却给出更高收率的二芳基酮及较少量的联芳烃付产物实验证明2-萘基重氮盐具有很好的反应活性和选择性总是得到优异的反应结果在此基础上由不同的芳基四氟硼酸重氮盐与芳基硼酸一氧化碳和氨气协同作用以上述含氮杂环卡宾作配体与乙酸钯生成的高活性含氮杂环卡宾钯催化剂催化较高收率地得到了芳基酰胺优化的反应条件是使用2mol的钯-H_2IPr 1五个大气压的一氧化碳以氨气饱和的四氢呋喃作溶剂由不同的有机硼化合物与三种芳基重氮盐的四组份偶联反应同时不仅对生成的多种产物进行了定 L-氮杂环丁烷-2-羧酸L-氮杂环丁烷-2-羧酸又称 S -氮杂环丁烷-2-羧酸简称为L-Aze1955年由Fowden从植物铃兰 Convallaria majalis 中分离得到成为第一个被证实的植物中天然存在的氮杂环丁烷结构作为一种非典型的氨基酸已经发现 S -氮杂环丁烷-2-羧酸可广泛用于对多肽结构的修饰以及诸如不对称的羰基还原Michael 加成环丙烷化和Diels-Alder反应等不对称合成中的多个领域本文通过对 S -氮杂环丁烷-2-羧酸合成路线的研究综述了五种可行的合成路线及方法通过比较选用以L-天冬氨酸为初始原料合成 S -氮杂环丁烷-2-羧酸的路线即通过酯化反应活泼氢保护格氏反应内酰胺化反应还原反应氨基保护氧化反应脱保护等反应来合成 S -氮杂环丁烷-2-羧酸分析了每步反应的机理并对 S -氮杂环丁烷-2-羧酸的应用及前景给予展望通过热分析红外质谱核磁等分析手段对合成的化合物的结构进行表征结果表明所得的产物符合目标产物所合成的化合物的结构性能指标与设计的目标要求一致每步反应的收率都在70％以上可以判定以L-天冬氨酸为初始原料合成 S -氮杂环丁烷的路线方案切实可行。
污水处理外文文献
Aerobic treatment of dairy wastewater with sequencing batch reactor systemsXiujin Li,Ruihong ZhangAbstract Performances of single-stage and two-stage se-quencing batch reactor(SBR)systems were investigated for treating dairy wastewater.A single-stage SBR system was tested with10,000mg/l chemical oxygen demand (COD)influent at three hydraulic retention times(HRTs) of1,2,and3days and20,000mg/l COD influent at four HRTs of1,2,3,and4days.A1-day HRT was foundsufficient for treating10,000-mg/l COD wastewater,with the removal efficiency of80.2%COD,63.4%total solids, 66.2%volatile solids,75%total Kjeldahl nitrogen,and 38.3%total nitrogen from the liquid effluent.Two-day HRT was believed sufficient for treating20,000-mg/l COD dairy wastewater if complete ammonia oxidation is not desired.However,4-day HRT needs to be used for achieving complete ammonia oxidation.A two-stage sys-tem consisting of an SBR and a complete-mix biofilm re-actor was capable of achieving complete ammonia oxidation and comparable carbon,solids,and nitrogen removal while using at least1/3less HRT as compared to the single SBR system.Keywords Aerobic,dairy,wastewater,sequencing batch reactor1IntroductionDairy wastewater is currently disposed of mainly through land application with little or no pretreatment in Califor-nia in the United States.Due to increasing awareness of the general public about potential adverse impact of ani-mal wastes on environmental quality and recent develop-ments in environmental regulations for gaseous-emission control and nutrient management,alternative wastewater treatment methods become attractive options for dairy producers.A sequencing batch reactor(SBR)is a biolog-ical treatment reactor that uses aerobic bacteria to degrade organic carbon and remove nitrogen present in the wastewater.If designed and operated properly,it maybecome a promising alternative for treating animal wastewater to control odors and reduce solids and nutrient contents.The SBR treats wastewater in small batches andfits wellwith most animal wastewater collection systems.It is atime-oriented system and operates over repeated cycles offive phases–fill,react,settle,decant,and idle.The major factors that control the performance of SBRs include or-ganic loading rate,hydraulic retention time(HRT),solids retention time(SRT),dissolved oxygen(DO),and influent characteristics such as chemical oxygen demand(COD),solids content,and carbon-to-nitrogen ratio(C/N),etc. Depending on how these parameters are controlled,theSBR can be designed to have one or more of these func-tions:carbon oxidation,nitrification,and denitrification[1,2].Carbon oxidation and denitrification are carried outby heterotrophic bacteria and nitrification is by auto-trophic bacteria.The SBR has been successfully used in the treatment of municipal and industrial wastewater,wherethe high treatment performance resulted in excellent ef-fluent quality[3,4].It is considered to be a suitable systemfor wastewater treatment applications in small communi-ties[5].The SBR is a relatively new technology for agri-cultural applications.Previous research on the SBR foranimal waste was primarily concentrated on swine wastewater treatment.Several researchers[6,7,8]re-ported the performance of SBR in treating swine waste-water with COD and suspended solids(SS)in the range of1,614–2,826mg/l and175–3,824mg/l,respectively.Satis-factory removal of COD and SS from the wastewater was achieved with HRTs of22–30h.Fernades et al.[9]studiedthe SBR for treating highly concentrated swine manurewith about4%total solids(TS).The influent COD,NH3-N,and total Kjeldahl nitrogen(TKN)were as high as31,175mg/l,1,265mg/l,and2,580mg/l,respectively.Their results indicated that above97%COD,99%NH3-N,and93%TKN removal efficiencies were achieved in theliquid effluent at HRTs of6and9days and SRT of over20days.Tam et al.[10]researched SBR for treatment of wastewater from a milking center and reported that the wastewater with919–1,330mg/l COD and15–37mg/lNH3-N could be successfully treated with a HRT of20h. Bioprocess Biosyst Eng25(2002)103–109DOI10.1007/s00449-002-0286-9103Received:2October2001/Accepted:6February2002 Published online:5April2002ÓSpringer-Verlag2002X.Li(&)Department of Environmental Engineering,Beijing University of Chemical Technology,100029,Beijing,ChinaE-mail:lxiujin@Tel.:+86-010-********Fax:+86-010-********R.ZhangBiological and Agricultural Engineering Department, University of California at Davis,CA95616,USAThis research was supported in part by the California Energy Commission and the Agricultural Experiment Station of the University of California,Davis,USA.Studies on the SBR for treating dairy manure are not well documented in the literature.Previous researchfindings about the SBR for treatment of swine manure and other types of wastewater provide valuable references for the treatment of dairy wastewater.However,due to the dif-ferences in the characteristics of dairy wastewater from other types of wastewater,research is needed to develop design and operational guidelines for the SBR in treating dairy wastewater of various characteristics.The objectives of this study are to investigate the effects of wastewater characteristics,HRT,SRT,and organic loading rate on the performance of the SBR system in treating dairy wastewater for carbon and solids removal and nitrogen conversion,and develop design and opera-tional guidelines for the SBR system in single-and mul-tiple-stage configurations.2Materials and methods2.1Dairy manure collection and preparationDairy manure was collected on the Dairy Research Farm of the University of California at Davis.Due to runoff of urine on the feedlot,the collected manure was mainly feces and contained a relatively low content of ammonia nitro-gen.The manure was slurried with addition of water and then screened twice with two sieves with openings of4·4 and2·2mm,respectively,to remove large particles.The screened manure was transported immediately to the laboratory and stored in a freezer at–20°C until use.The TS and COD of the screened manure were30,000–40,000mg/l and35,000–50,000mg/l,respectively.When needed,the stored manure was thawed and then diluted with tap water to obtain a desired COD concentration.Due to relatively low ammonia content of the raw manure as compared to typical levels in the manure collected on dairy farms,urea was added to increase the NH3-N in the prepared manure from100–125mg/l to500–550mg/l.The prepared manure was then put into a50-l feeding tank housed in a refrigerator at4°C for daily use.The feeding tank had an agitator to mix the wastewater during the feeding of the reactors.2.2Experimental setup and operationBoth single-stage and two-stage treatment systems were tested.The single-stage SBR system consisted of an SBR and a solids-settling tank in series.The wastewater wasfirst fed into the SBR for treatment and the effluent of the SBR, including both sludge and liquid,was then discharged into a settling tank,where liquid was separated from sludge by gravity settling and characterized as liquid effluent of the system.The two-stage system consisted of an SBR(first-stage reactor),a solids-settling tank,and a complete-mix biofilm reactor(CMBR)(second-stage reactor)connected in series.The liquid effluent obtained from the solids-set-tling tank was used as influent of CMBR and further treated in the CMBR for achieving complete nitrification.The two-stage SBR-CMBR system is shown in Fig.1.Each system was fed and decanted twice a day for12h in each treatment cycle.All the peristaltic pumps used for feeding and decanting were operated automatically with a digital time controller.The time sequence for different operations during each treatment cycle of the SBR was1–3minfill,11h and4–8min react,40min settle,1–3min decant,and10min idle.The CMBR was operated as a complete-mix reactor and had long SRT provided by the attached growth on the polyethylene pellets placed in the reactor.The plastic pellets had light density(920kg/ m3)and were keptfluidized with the airflow.Each pellet was10mm in diameter and10mm in height,with a cross inside the cylinder and longitudinalfins on the outside, providing a large surface area for bacterial attachment. Thefilling volume of the pellets in total occupied ap-proximately18%of liquid volume(3l)in the reactor.The SBR and CMBR reactors were made from trans-parent acrylic and had a total volume of6l each,with51cm height and12cm diameter.During testing,the liquid vol-ume of each reactor was3l.Each reactor was aerated using pressurized air at a controlledflow rate.In order to mini-mize the water evaporation in the reactor,the air was hu-midified by traveling through water contained in a15-l jar prior to entering the reactor.The air was evenly distributed into the wastewater through four air stone diffusers in-stalled near the bottom of the reactor.All the reactors were initially seeded with the activated sludge obtained from the UC Davis Wastewater Treatment Plant and allowed to ac-climate for about2months before formal experiments were started.It normally took about4weeks for each SBR re-actor to reach a steady state when a new operating condi-tion was introduced.The steady state was defined to be a state when the weekly variations of effluent COD,TS,NH3-N,and pH were less than5%.These parameters were monitored twice a week.The CMBR had been fully accli-mated with dilute dairy wastewater for about6months and had nitrification bacteria well established before being connected with the SBR.The mixed liquor suspended solids (MLSS)in the CMBR was about10,000mg/l,which was calculated from both suspended growth and attached growth solids.In order to determine the ammonia emission from SBR due to aeration,ammonia in the exiting air of SBR was collected by absorbing it in0.3N boric acid solution for 24h under each testing condition.2.3Experimental plan and system performance evaluation The experiment was carried out in two phases.Thefirst phase was for studying the effects of influent characteris-tics,HRT,and corresponding SRT and loading rate on the performance of the single-stage SBR system.The second phase was to evaluate the performance of a two-stage SBR-CMBR system.The two systems were then compared in terms of carbon and solids removal and nitrogen conver-sion efficiencies.With the single-stage SBR system,three HRTs(1,2and 3days)were tested for wastewater of10,000mg/l COD and four HRTs(1,2,3and4days)for wastewater of20,000mg/l COD.For the wastewater of10,000mg/l COD, the corresponding loading rate and SRT for the three HRTs were10,5,and3.3g COD/l/day and8,12,andBioprocess Biosyst Eng25(2002) 10415days,respectively.For the wastewater of 20,000mg/l COD,the corresponding loading rate and SRT for the four HRTs were 20,10,6.7,and 5g COD/l/day and 1.5,3,4,and 6days,respectively.With the two-stage SBR system,2days was used first as the system HRT,with 1day for the first-stage and 1day for the second-stage for both in flu-ents,and then 2.5days was used with 2days for the first stage and 0.5days for the second stage.An air flow rate of 4l/min was applied for all runs,which was able to main-tain dissolved oxygen (DO)in the SBR and CMBR above 3mg/l.The performance of the treatment systems was evalu-ated in terms of carbon and solids removal and nitrogen conversion ef ficiencies.The parameters analyzed included TS,volatile solids (VS),COD,SCOD (soluble COD),TKN,NH 3-N,NO 2-N,and NO 3-N.Two kinds of removal/con-version ef ficiencies were used to interpret the results for carbon and solids removal and nitrogen oxidation.One ef ficiency,E t ,is based on the removal from total ef fluent (including both sludge and liquid ef fluent generated),re-flecting the removal ef ficiency through biological process alone.The other ef ficiency,E l ,was based on the removal from liquid ef fluent,i.e.,supernatant,representing the removal ef ficiency through both biological process and sludge separation.For the single-stage SBR system,the total ef fluent was the ef fluent from the SBR and the liquid ef fluent was the supernatant decanted from the solids settling tank.For the two-stage SBR-CMBR system,the total ef fluent was the combination of sludge from the settling tank and the final ef fluent from CMBR,and the liquid ef fluent was the liquid ef fluent of CMBR.Most of previous research only reports removal ef ficiency from liquid ef fluent (E l ).Actually,E l does not re flect the real capability of a system for removing various constituents from wastewater,because part of these constituents are contained in the sludge that is separated from the liquid ef fluent and discharged as a separate sludge stream.Therefore,E t needs to be used in order to assess the real capability of a system for removing various constituents from wastewater.2.4Sampling and analytical methodsAfter each reactor reached steady state under testing conditions,samples were taken from the in fluent,mixed liquor,total ef fluent,and liquid ef fluent of the reactor three times a week (every other day)for analyses of COD,SCOD,TS,VS,NH 3-N,NO 2-N,NO 3-N,and TKN.The re-moval ef ficiencies,E l and E t ,were calculated based on the data from in fluent,liquid ef fluent,and total ef fluent of the systems.The separation of sludge and liquid in the total ef fluent of the SBR was performed by settling the ef fluent in a 1-l graduated cylinder for 2h and then decanting the liquid fraction above the sludge-liquid interface line.The COD,SCOD,TS,VS,and TKN were measured according to APHA standard methods [11].The COD measured in this study was COD Cr .The pH was measured with an Accumet pH meter (Fisher Scienti fic,Pittsburgh,Pa.).The NH 3-N was measured with a gas-sensing elec-trode and the pH meter.The DO in the reactors wasmonitored on a daily basis with a DO meter (YSI Mode158,Fisher Scienti fic,Pittsburgh,Pa.).The NO 2-N was analyzed with the HACH method,using a DR/2000spectropho-tometer [12].The NO 3-N was measured with a diffusion –conductivity analyzer [13].3Results and discussion3.1Performance of the single-stage SBR system3.1.1Removal of carbon and solidsThe performance data of the SBR for 10,000mg/l COD in fluent COD of 10,000are shown in Table 1.With the increase of HRT from 1to 3days,the COD,SCOD,TS,and VS in the liquid ef fluent became lower,yielding better ef fluent quality due to increased biological conversion and improved sludge settleability,as indicated by the increased removal ef ficiencies (E l and E t ).However,there wasnoboratory setup for a two-stage SBR-CMBR system for dairy wastewater treatmentX.Li,R.Zhang:Aerobic treatment of dairy wastewater with sequencing batch reactor systems105signi ficant difference in terms of carbon and solids rem-ovals and liquid ef fluent quality for the three HRTs.For example,the increase of COD and TS removal ef ficiency E l was 5.1%and 0.3%,and E t was 5.7%and 2.0%,respec-tively,when HRT increased from 1to 3days.Therefore,1-day HRT was believed to be suf ficient for treating the dairy wastewater with 10,000mg/l COD for its satisfactory removal ef ficiency and relatively short HRT.At 1-day HRT,the removal ef ficiency from the liquid ef fluent (E l )was 80.2%for COD,63.4%for TS,and 66.2%for VS.These removals were due to both biological conversion in the SBR and sludge separation in the solids-settling tank.The removal due to biological conversion alone in the SBR,as measured by E t ,was 45.0%for COD,21.4%for TS,and 34.2%for VS.E t was signi ficantly greater than E l ,sug-gesting that the sludge separation after SBR treatment is necessary for achieving signi ficant carbon and solids re-moval from the dairy wastewater.It was found that aerobic treatment greatly enhanced the flocculation and settlea-bility of the solids in the wastewater.Good settleability of sludge was important for achieving high carbon and solids removal ef ficiency.The performance data of the SBR for 20,000mg/l COD in fluent are shown in Table 2.The 1-day HRT was tested first.It was found that it was impossible to control the SRT at a desired level due to fast solids buildup in the reactor and poor solids settleability.When the HRT was increased to 2days,there was signi ficant improvement in the ef fluent quality and increase of removal ef ficiencies.However,when the HRT was further increased to 3days,the changes in the ef fluent quality,COD,and solids removals were not signif-icant.Therefore,2-day HRT was considered enough for COD and solids removal for 20,000mg/l COD in fluent due to its relatively short retention time and high removal ef fi-ciency.At 2-day HRT,the removal ef ficiency E l of COD,SCOD,TS,and VS was 85.7%,67.1%,71.0%,and 70.6%,respectively,and E t was 35.9%,67.1%,22.8%,and 25.6%,respectively.The 4-day HRT was tested for achieving com-plete ammonia conversion.Since ammonia was not com-pletely converted at 2-day and 3-day HRT,longer HRT was needed when complete nitri fication was desired.This will be further discussed in the following nitrogen removal section.The sludge separated from the ef fluent of the SBR contained 4.1–5.9%TS.The lower in fluent COD(10,000mg/l)resulted in better sludge settleability than the higher in fluent COD (20,000mg/l).The sludge volume as the fraction of total ef fluent volume was 5–6%and 13–16%for the lower and higher levels of in fluent COD,respectively.The sludge was composed of not-degraded solids in the wastewater and newly formed bacterial cells.It can be further processed into organic soil amendment through dewatering and composting.Table 1.Ef fluent quality and treatment ef ficiencies of SBR for 10,000mg/l COD in fluentParametersIn fluent (mg/l)1-day HRT 2-day HRT3-day HRT Liquid ef fluent Total ef fluent E l (%)E t (%)Liquid ef fluent Total ef fluent E l (%)E t (%)Liquid ef fluent Total ef fluent E l (%)E t (%)(mg/l)(mg/l)(mg/l)(mg/l)(mg/l)(mg/l)COD 10,0001,9806,50080.245.01,5805,13084.248.71,4704,93085.350.7SCOD 2,9141,4571,45750.050.01,4511,45150.250.21,4281,42851.051.0TS 6,6562,4365,23263.421.42,4765,07962.823.72,4165,09863.723.4VS 5,1081,7243,36166.234.21,5323,24970.036.41,4003,16772.638.0TKN 7801953657553.218535476.354.616533878.856.7TN 78048160738.322.248059838.523.447459639.223.6NH 3-N 51012012076.576.510510579.479.4707086.386.3NO 3-N 0375545NO 2-N 024*******pH8.16.86.76.7Table 2.Ef fluent quality and treatment ef ficiencies of SBR for 20,000mg/l COD in fluentPara-meters In fluent (mg/l)1-day HRT 2-day HRT 3-day HRT 4-day HRTLiquid ef fluent Total ef fluent E l (%)E t (%)Liquid ef fluent Total ef fluent E l (%)E t (%)Liquid ef fluent Total ef fluent E l (%)E t (%)Liquid ef fluent Total ef fluent E l (%)E t (%)(mg/l)(mg/l)(mg/l)(mg/l)(mg/l)(mg/l)(mg/l)(mg/l)COD 20,0004,30013,92078.530.42,87012,82085.735.92,66012,32086.738.4167010,90091.743.3SCOD 6,6603,1973,19752.052.02,1902,19067.167.12,0052,00569.969.912151,21581.881.8TS 12,4424,36710,11564.918.73,6129,60571.022.83,4989,58071.923.033509,19573.124.3VS 10,1043,1427,92268.921.62,9727,51770.625.62,8097,33672.227.424607,05375.729.5TKN 1,14054089952.621.118063884.244.017060085.147.48550092.552.3TN 1,14057393349.718.248491857.519.548891857.219.538888863.020.5NH 3-N 54031031042.642.6828284.884.8808085.285.200100100NO 3-N 020*********NO 2-N 01314013010pH8.08.77.97.87.6Bioprocess Biosyst Eng 25(2002)1063.1.2Nitrogen conversionWith the influent of10,000mg/l COD and1-to3-day HRT,22.2–23.6%of total nitrogen(TN)was lost in the treatment process as indicated by the E t.The losses of TN for the three HRTs were not significantly different.The ammonia collection results showed that the amount of NH3-N volatilized accounted for only2–3%of TN,indi-cating that the ammonia loss through volatilization was small under these operating conditions.The rest of TN loss (approximately20%)might be due to the emission of other nitrogenous gases,such as nitrous oxides(NO and NO2)formed in the nitrification process,and nitrogen gas (N2)formed in the denitrification process.The TKN removal was53.2–56.7%from the total effluent and75–78.8%from the liquid effluent,respectively.The TKN removal mainly resulted from ammonia oxidation.With the influent of20,000mg/l COD and1-to4-day HRTs,the loss of TN was18.2–20.5%.For the1-day HRT, the ammonia collection results showed that ammonia volatilization accounted for16%of TN,indicating that most of TN loss was due to ammonia volatilization.This occurred with the low nitrification rate in the SBR.But ammonia volatilization was insignificant at2-to4-day HRTs,at which the SBR had high nitrification activities. These results might imply that ammonia volatilization could be related to nitrification activity.Little nitrification occurrence at1-day HRT was due to the short SRT of 1.5days.This agrees with thefindings of Prakasam and Loehr[14],who stated that2-day SRT was the minimum for nitrification of poultry wastes.Therefore,HRT was increased to2days and3days,and corresponding SRT were3days and4days.It was found that nitrification was able to sustain in the SBR at both HRTs.At2-day and3-day HRT,the TN and TKN removals were19.5%and44.0–47.4%from the total effluent,and57.5–57.2%and84.2–85.1%from the liquid effluent,respectively.Significant NH3-N was removed,as indicated by removal efficiency of 84.8%for2-day HRT and85.2%for3-day HRT,although there was still80–82mg/l residual NH3-N present in the effluent.It can be seen that there was no significant dif-ference between two HRTs in terms of TN,TKN,and NH3-N removal.Therefore,if complete ammonia oxidation is not required,2-day HRT would be considered efficient for treating20,000mg/l COD influent in terms of both nitrogen removal discussed here and COD and solids removal as mentioned in Sect.3.1.1.Certain amounts of residual ammonia were present in the effluent from20,000mg/l COD influent at2-day and 3-day HRT.This indicates that the nitrification process might have been inhibited in both operation conditions. Nitrification inhibition might be due to possible inhibitions of nitrification bacteria by free ammonia(FA)and free nitrous acids(FNA)and suppression of nitrification bac-teria by more competitive heterotrophic bacteria[15].NH3 was undesirable because of its odor and toxicity to aquatic lives;thus,it needed to be removed from the wastewater. Shammas[16]studied the interaction of temperature,pH, and biomass on the nitrification process and concluded that high nitrification efficiency can only be obtained with either very long detention time or a combination of highsolids concentration and elevated temperature.Therefore,HRT was further increased to4days in order to obtain complete ammonia conversion.It was found that4-dayHRT,corresponding6-day SRT,was enough for complete ammonia conversion,as indicated by zero ammonia pre-sent in the effluent(see Table2).Therefore,it could be concluded that if complete ammonia conversion is desired,4-day HRT would be needed for treating20,000mg/l COD wastewater with540mg/l NH3-N.A track study was conducted in order to further un-derstand the nitrification process in the SBR.The varia-tions of NH3-N,NO2-N,and NO3-N in the SBR during a12-h operating cycle in treating the wastewater of10,000mg/l COD at2-day HRT are shown in Fig.2.Am-monia oxidation mostly occurred in thefirst5h,as indi-cated by the increase of NO2-N and decrease of NH3-N.Since a large amount of ammonia was oxidized in the earlystage of one cycle with high nitrification,the amount of ammonia volatilization may be decreased in contrast tothe condition when nitrification is small as mentionedabove.The relationship between ammonia volatilizationand nitrification activity needs to be further investigated infuture study.The pH could be another factor related to ammonia volatilization.Since higher medium pH in-creased the gas fraction of total ammonia dissolved in the medium,ammonia volatilization could have been highwhen there was little nitrification and pH maintained rel-atively high(approximately8.0),but small when there wasgood nitrification and the pH was decreased(Fig.2).TheNO2-N increased to the peak value about5h later after feeding and then started to decrease,while NO3-N startedto increase slightly.Generally speaking,the variations ofNH3-N,NO2-N,NO3-N,and pH in the SBR during the operating cycle depends on the bioconversion dynamics inthe reactor,initial ammonia concentration,and alkalinityin the wastewater.3.2Performance of the two-stage SBR-CMBR systemAs stated above,a4-day HRT is needed for achieving complete oxidation of ammonia in the dairy wastewaterin107the single-stage SBR.It appears that increasing HRT to achieve complete nitri fication is not cost effective.This led us to explore a two-stage treatment system.Research showed that nitrifying in a separate second-stage aeration system would increase nitri fication rate,due to the more suitable environment provided by a two-stage system than a single-stage system [17].In aerobic treatment,carbon oxidation is carried out by heterotrophic bacteria,while nitri fication is carried out by autotrophic bacteria.The two groups of bacteria are signi ficantly different in physiology,substrate requirement,metabolic characteristics,and growth kinetics.In a single-stage system,both carbon oxidation and nitri fication proceed in one reactor.This forces two groups of bacteria to coexist within the same physical and chemical environment,which is not optimal for either autotrophic or heterotrophic bacteria and makes it dif ficult to achieve optimum carbon and ammonia ually,longer HRT is applied in a single-stage system to balance the slow-growing autotrophic bacteria responsible for nitri fication and fast-growing he-terotrophic bacteria for carbon oxidation.But this is not economical,as mentioned above.A two-stage system could separate carbon oxidation and the nitri fication process and make each process proceed in a separate re-actor.The first-stage reactor is intended mainly for carbon oxidation and enhancement of solids settleability,and the second-stage reactor for providing suitable conditions fornitri fication.Since carbon could be oxidized quickly by fast-growing heterotrophic bacteria,the first-stage reactorcould use a relatively shorter HRT.After the first-stage SBR treatment,the solids settleability is improved as well,the sludge generated is separated and the liquid ef fluent is used as in fluent for the second-stage reactor.Sludge sep-aration would signi ficantly increase the system removal ef ficiency and reduce concentrations of constituents such as COD,TS,and NH 3-N in the in fluent,making it possible to use a shorter HRT,while maintaining a longer SRT for nitri fication in the second-stage reactor.With the opti-mization of environmental conditions and substratecharacteristics for heterotrophic and autotrophic bacteria in separate stages as mentioned above,the overall per-formance of the two-stage system can be improved and overall HRT reduced,as indicated from the performance data presented below.The two-stage system consisted of one SBR as the first stage and one CMBR as the second stage.The CMBR was selected to be the second-stage reactor,because the at-tached bacteria growth supported by the polyethylene pellets were believed to be favorable for nitri fication bac-teria by providing a long SRT.The CMBR was used to treat the liquid ef fluent from the SBR.Both SBR and CMBR were first operated at 1-day HRT,with the system HRT being 2days for treating 10,000mg COD/l and 20,000mg COD/l in fluent,respectively.The 1-day HRT in the CMBR was determined to be the appropriate level,based on preliminary test results.The performance data of the two-stage system are shown in Tables 3and 4.It can be seen that the liquid ef fluent quality and removal ef ficiencies of carbon,solids,and nitrogen from the two-stage system at 2-day HRT were comparable to those from the single-stage SBR at 3-day HRT for both in fluents.This suggests that,based on the HRT,the two-stage system would require 1/3less reactor volume than the single-stage system and therefore appears to have more favorable economics.In addition,the two-stage system allows complete ammonia oxidation in the wastewater as indicated by zero NH 3-N present in the two-stage system ef fluent at 2-day HRT as compared to 70mg/l NH 3-N in the one-stage ef fluent at 3-day HRT.Because with the in fluent of 20,000mg/l COD ammonia volatilization was high in the first-stage SBR at 1-day HRT,Table 3.Performance of two-stage SBR-CMBR system for 10,000mg/l COD in fluent In fluent (mg/l)Stage I:SBR(1-day HRT)Stage II:CMBR (1-day HRT)E l (%)E t (%)Liquid ef fluent Liquid ef fluent (mg/l)(mg/l)COD 10,0001,9801,37486.351.1SCOD 2,9141,4571,01465.265.2TS 6,6562,4362,07668.824.8VS 5,1081,7241,47271.239.1TKN 7801956092.358.0TN 78048143544.224.7NH 3-N 510120 2.599.599.5NO 3-N 037195NO 2-N 0249180pH 8.16.87.9Table 4.Performance of the two-stage SBR-CMBR system for 20,000mg/l COD in fluentIn fluent (mg/l)stage I:SBR (1-day HRT)stage II:CMBR (1-day HRT)E l (%)E t (%)stage I:SBR (2-day HRT)stage II:CMBR (0.5-day HRT)E l (%)E t (%)Liquid ef fluent Liquid ef fluent Liquid ef fluent Liquid ef fluent (mg/l)(mg/l)(mg/l)(mg/l)COD 20,0004,3002,67686.637.028********.543.8SCOD 6,6603,1972,02069.769.7219089086.686.6TS 12,4424,3673,43272.421.83612267078.526.4VS 10,1043,1422,15278.727.029********.532.5TKN 1,14054018084.246.11804096.556.2TN 1,14057350455.823.248443062.321.5NH 3-N 540310 3.099.499.4820100100NO 3-N 020*********NO 2-N 0131341400pH 8.08.77.87.97.4Bioprocess Biosyst Eng 25(2002)108。
污水处理的英文文献翻译(1)
Nutrient removal in an A2O-MBR reactor with sludgereductionABSTRACTIn the present study, an advanced sewage treatment process has been developed by incorporating excess sludge reduction and phosphorous recovery in an A2O-MBR process. The A2O-MBR reactor was operated at a flux of 77 LMH over a period of 270 days. The designed flux was increased stepwise over a period of two weeks. The reactor was operated at two different MLSS range. Thermo chemical digestion of sludge was carried out at a fixed pH (11)and temperature (75℃) for 25% COD solubilisation. The released pbospborous was recovered by precipitation process and the organics was sent back to anoxic tank. The sludge digestion did not have any impact on COD and TP removal efficiency of the reactor. During the 270 days of reactor operation, the MBR maintained relatively constant transmembrane pressure. The results based on the study indicated that the proposed process configuration has potential to reduce the excess sludge production as well as it didn't detonated the treated water quality.Keywords: A2O reactor; MBR; Nutrient removal; TMP1. IntroductionExcess sludge reduction and nutrients removal are the two important problems associated with wastewater treatment plant. MBR process has been known as a process with relatively high decay rate and less sludge production due to much longer sludge age in the reactor (Wenet al., 2004). Sludge production in MBR is reduced by 28-68%, depending on the sludge age used (Xia et al.,2008). However, minimizing the sludge production by increasing sludge age is limited due to the potential adverse effect of high MLSS concentrations on membrane (Yoon et al., 2004). This problem can be solved by introducing sludge disintegration technique in MBR (Young et al., 2007). Sludge disintegration techniques have been reported to enhance the biodegradability of excess sludge (Vlyssides and Karlis, 2004). In overall, the basis for sludge reduction processes is effective combination of the methods for sludge disintegration and biodegradation of treated sludge. Advances in sludge disintegration techniques offer a few promising options including ultrasound (Guo et al., 2008), pulse power (Choi et al.,2006), ozone (Weemaes et al., 2000), thermal (Kim et al., 2003), alkaline (Li et al., 2008) acid (Kim et al., 2003) and thermo chemical(Vlyssides and Karlis, 2004). Among the various disintegration techniques, thermo chemical was reported to be simple and cost effective (Weemaes and Verstraete, 1998). In thermal-chemical hydrolysis, alkali sodium hydroxide was found to be the most effective agent in inducing cell lysis (Rocker et al., 1999). Conventionally, the nutrient removal was carried out in an A2O process. It has advantage of achieving, nutrient removal along with organic compound oxidation in a single sludge configuration using linked reactors in series (Tchobanoglous et al., 2003). The phosphoroes removal happens by subjecting phosphorous accumulating organisms (PAO) bacteria under aerobic and anaerobic conditions (Akin and Ugurlu, 2004). These operating procedures enhance predominance PAO, which are able to uptake phosphorous in excess. During the sludge pretreatment processes the bound phosphorous was solubilised and it increases the phosphorousconcentration in the effluent stream (Nishimura, 2001).So, it is necessary to remove the solubilised phosphorus before it enters into main stream. Besides, there is a growing demand for the sustainable phosphorous resources in the industrialized world. In many developed countries, researches are currently underway to recover the phosphoroes bound in the sludge's of enhanced biological phosphorus removal system (EBPR). The released phosphorous can be recovered in usable products using calcium salts precipitation method. Keeping this fact in mind, in the present study, a new advanced wastewater treatment process is developed by integrating three processes, which are: (a) thermo chemical pretreatment in MBR for excess sludge reduction (b) A2O process for biological nutrient removal (c) P recovery through calcium salt precipitation. The experimental data obtained were then used to evaluate the performance of this integrated system.2. Methods2.1. WastewaterThe synthetic domestic wastewater was used as the experimental influent. It was basically composed of a mixed carbon source, macro nutrients (N and P), an alkalinity control (NaHCO3) and a microelement solution. The composition contained (/L) 210 mg glucose, 200 mg NH4C1, 220 mg NaHCO3, 22一34 mg KH2PO4, microelement solution (0.19 mg MnCl2 4H20, 0.0018 mg ZnCl22H2O,0.022 mg CuCl22H2O, 5.6 mg MgSO47H2O, 0.88 mg FeCl36H2O,1.3 mg CaCl2·2H2O). The synthetic wastewater was prepared three times a week with concentrations of 210±1.5 mg/L chemical oxygen demand (COD), 40±1 mg/L total nitrogen (TN) and 5.5 mg/L total phosphorus (TP).2.2. A2O-MBRThe working volume of the A2O-MBR was 83.4 L. A baffle was placed inside the reactor to divide it into anaerobic (8.4 L) anoxic (25 L) and aerobic basin (50 L). The synthetic wastewater was feed into the reactor at a flow rate of 8.4 L/h (Q) using a feed pump. A liquid level sensor, planted in aerobic basin of A2O-MBR controlled the flow of influent. The HRT of anaerobic, anoxic and aerobic basins were 1, 3 and 6 h, respectively. In order to facilitate nutrient removal, the reactor was provided with two internal recycle (1R). IRl (Q= 1)connects anoxic and anaerobic and IR 2 (Q=3) was between aerobic and anoxic. Anaerobic and anoxic basins were provided with low speed mixer to keep the mixed liquid suspended solids (MLSS) in suspension. In the aerobic zone, diffusers were used to generate air bubbles for oxidation of organics and ammonia. Dissolved oxygen (DO) concentration in the aerobic basin was maintained at 3.5 mg/1 and was monitored continuously through online DO meter. The solid liquid separation happens inaerobic basin with the help of five flat sheet membranes having a pore size of 0.23 pm. The area of each membrane was 0.1 m2. They were connected together by a common tube. A peristaltic pumpwas connected in the common tube to generate suction pressure. In the common tube provision was made to accommodate pressure gauge to measure transmembrane pressure (TMP) during suction. The suction pump was operated in sequence of timing, which consists of 10 min switch on, and 2 min switch off.2.3. Thermo chemical digestion of sludgeMixed liquor from aerobic basin of MBR was withdrawn at the ratio of 1.5% of Q/day and subjected to thermo chemical digestion. Thermo chemical digestion was carried out at a fixed pH of 11(NaOH) and temperature of 75℃for 3 h. After thermo chemical digestion the supernatant and sludge were separated. The thermo-chemicallydigested sludge was amenable to further anaerobic bio-degradation (Vlyssides and Karlis, 2004), so it was sent to theanaerobic basin of the MBR2.4. Phosphorus recoveryLime was used as a precipitant to recover the phosphorous in the supernatant. After the recovery of precipitant the content was sent back to anoxic tank as a carbon source and alkalinity supelement for denitrification.2.5. Chemical analysisCOD, MLSS, TP, TN of the raw and treated wastewater were analyzed following methods detailed in (APHA, 2003). The influent and effluent ammonia concentration was measured using an ion-selective electrode (Thereto Orion, Model: 95一12). Nitrate in the sample was analyzed using cadmium reduction method (APHA, 2003).3. Results and discussionFig. 1 presents data of MLSS and yield observed during the operational period of the reactor. One of the advantages of MBR reactor was it can be operated in high MLSS concentration. The reactor was seeded with EBPR sludge from the Kiheung, sewage treatment plant, Korea. The reactor was startup with the MLSS concentration of 5700 mg/L. It starts to increase steadily with increase in period of reactor operation and reached a value of 8100 mg/L on day 38. From then onwards, MLSS concentration was maintained in the range of 7500 mg/L by withdrawing excess sludge produced and called run I. The observed yields (Yobs) for experiments without sludge digestion (run I) and with sludge digestion were calculated and given in Fig. 1. The Yobs for run I was found to be 0.12 gMLSS/g COD. It was comparatively lower than a value of 0.4 gMLSS/g CODreported for the conventional activated sludge processes (Tchoba-noglous et al., 2003). The difference in observed yield of these two systems is attributed to their working MLSS concentration. At high MLSS concentration the yield observed was found to be low (Visva-nathan et al., 2000). As a result of that MBR generated less sludge.The presently used MLSS ranges (7.5一10.5 g/L) are selected on the basis of the recommendation by Rosenberger et al. (2002). In their study, they reported that the general trend of MLSS increase on fouling in municipal applications seems to result in no impact at medium MLSS concentrations (7一12 g/L).It is evident from the data that the COD removal efficiency of A2O system remains unaffected before and after the introduction of sludge digestion practices. A test analysis showed that the differences between the period without sludge digestion (run I) and with sludge digestion (run II and III) are not statistically significant.However, it has been reported that, in wastewater treatment processes including disintegration-induced sludge degradation, the effluent water quality is slightly detonated due to the release of nondegradable substances such as soluble microbial products (Ya-sui and Shibata, 1994; Salcai et al., 1997; Yoon et al., 2004). During the study period, COD concentration in the aerobic basin of MBR was in the range of 18-38 mg/L and corresponding organic concentration in the effluent was varied from 4 to 12 mg/L. From this data it can be concluded that the membrane separation played an important role in providing the excellent and stable effluent quality.Phosphorus is the primary nutrient responsible for algal bloom and it is necessary to reduce the concentration of phosphorus in treated wastewater to prevent the algal bloom. Fortunately its growth can be inhibited at the levels of TP well below 1 mg/L (Mer-vat and Logan, 1996).Fig. 2 depicts TP removal efficiency of the A2O-MBR system during the period of study. It is clearly evident from the figure that the TP removal efficiency of A/O system was remains unaffected after the introduction of sludge reduction. In the present study, the solubilised phosphorous was recovered in the form of calcium phosphate before it enters into main stream. So, the possibility of phosphorus increase in the effluent due to sludge reduction practices has been eliminated. The influent TP concentration was in the range of 5.5 mg/L. During thefirst four weeks of operation the TP removal efficiency of the system was not efficient as the TP concentration in the effluent exceeds over 2.5 mg/L. The lower TP removal efficiency during the initial period was due to the slow growing nature of PAO organisms and other operational factors such as anaerobic condition and internal recycling. After the initial period, the TP removal efficiency in the effluent starts to increase with increase in period of operation. TP removal in A2O process is mainly through PAO organisms. These organisms are slow growing in nature and susceptible to various physicochemical factors (Carlos et al., 2008). During the study period TP removal efficiency of the system remains unaffected and was in the range of 74-82%.。
给水处理-外文文献原文+翻译
膜技术和环境保护中的水处理Membrane technology and water treatment in environmental protectionREN J ianxin1 , ZHANGBaocheng2(1.China National Blue Star Chemical Cleaning Co. ， No。
9 West Road ， BeituchengChaoyang District ，Beijing 100029 , China2。
Department of Chemical Engineering ， Polytechnic of Turin , Corso Duca degli Abruzzi 24 ,Torino 10129 , Italy）Abstract : The paper present s a general summary on the state of the water resource and membrane industry of China。
Now the water pollution is becoming more grave ， and the water resource is shorter and shorter in the earth。
China ha s660 cities ,360 cities of them are short of water. The situation in 110 cities is serious ， and the situation in 40 cities is dangerous。
It was predicted that the water could be a main cause of local conflict s and international wars。
污水处理外文文献SBR
Bioprocess Biosyst Eng 25 (2002) 103–109DOI 10.1007/s00449-002-0286-9Aerobic treatment of dairy wastewater with sequencingbatch reactor systemsXiujin Li, Ruihong Zhang103Abstract Performances of single-stage and two-stage se-quencing batch reactor (SBR) systems were investigated for treating dairy wastewater. A single-stage SBR system was tested with 10,000 mg/l chemical oxygen de mand (COD) influent at three hydraulic retention times (HRTs) of 1, 2, and 3 days and 20,000 mg/l COD influent at four HRTs of 1, 2, 3, and 4 days. A 1-day HRT was f ound sufficient for treating 10,000-mg/l COD wastewater, with the removal efficiency of 80.2% COD, 63.4% total solids, 66.2% volatile solids, 75% total Kjeldahl nitrogen, and 38.3% total nitrogen from the liquid effluent. Tw o-day HRT was believed sufficient for treating 20,000-mg/l COD dairy wastewater if complete ammonia oxidation is not desired. However, 4-day HRT needs to be used for achieving complete ammonia oxidation. A two-stage sys- tem consisting of an SBR and a complete-mix biofilm re- actor was capable of achieving complete ammonia oxidation and comparable carbon, solids, and nitrogen removal while using at least 1/3 less HRT as compared to the single SBR system. ments in environmental regulations for gaseous-emission control and nutrient management, alternative wastew ater treatment methods become attractive options for dairy producers. A sequencing batch reactor (SBR) is a biolo g- ical treatment reactor that uses aerobic bacteria to degrade organic carbon and remove nitrogen present in the wastewater. If designed and operated properly, it may become a promising alternative for treating animal wastewater to control odors and reduce solids and nutrient conte nts.The SBR treats wastewater in small batches and fits well with most animal wastewater collection systems. It is a time-oriented system and operates over repeated cycles of five phases – fill, react, settle, decant, and idle. The major factors that control the performance of SBRs include or- ganic loading rate, hydraulic retention time (HRT), solids retention time (SRT), dissolved oxygen (DO), and influent characteristics such as chemical oxygen demand (COD), solids content, and carbon-to-nitrogen ratio (C/N), etc. Depending on how these parameters are controlled, the SBR can be designed to have one or more of these func- tions: carbon oxidation, nitrification, and denitri fication [1, 2]. Carbon oxidation and denitrification are carried out by heterotrophic bacteria and nitrification is by auto- trophic bacteria. The SBR has been successfully used in the treatment of municipal and industrial wastewater, where the high treatment performance resulted in excellent ef- fluent quality [3, 4]. It is considered to be a suitable system for wastewater treatment applications in small commun i- ties [5]. The SBR is a relatively new technology for agri- cultural applications. Previous research on the SBR for animal waste was primarily concentrated on swine wastewater treatment. Several researchers [6, 7, 8] re- ported the performance of SBR in treating swine waste- water with COD and suspended solids (SS) in the range of 1,614–2,826 mg/l and 175–3,824 mg/l, respectively. Satis- factory removal of COD and SS from the wastewater was achieved with HRTs of 22–30 h. Fernades et al. [9] studied the SBR for treating highly concentrated swine manure with about 4% total solids (TS). The influent COD, NH3-N, and total Kjeldahl nitrogen (TKN) were as high as31,175 mg/l, 1,265 mg/l, and 2,580 mg/l, res pectively. Their results indicated that above 97% COD, 99% NH3-N, and 93% TKN removal efficiencies were achieved in the liquid effluent at HRTs of 6 and 9 days and SRT of over 20 days. Tam et al. [10] researched SBR for treatment of wastewater from a milking center and reported that the wastewater with 919–1,330 mg/l COD and 15–37 mg/lNH3-N could be successfully treated with a HRT of 20 h.Keywords Aerobic, dairy, wastewater, se quencing batch reacto r1IntroductionDairy wastewater is currently disposed of mainly through land application with little or no pretreatment in Califor- nia in the United States. Due to increasing awareness of the general public about potential adverse impact of ani- mal wastes on environmental quality and recent d e velop-Received: 2 October 2001 / Accepted: 6 February 2002Published online: 5 April 2002Springer-Verlag 2002X. Li (&)Department of Environmental Engineering,Beijing University of Chemical Technology,100029, Beijing, ChinaE-mail:*******************Tel.: +86-010-********Fax: +86-010-********R. ZhangBiological and Agricultural Engineering Department,University of California at Davis, CA 95616, USAThis research was supported in part by the California Energy Commission and the Agricultural Experiment Station of the University of California, Davis, USA.Bioprocess Biosyst Eng 25 (2002)Studies on the SBR for treating dairy manure are not well documented in the literature. Previous research fi ndings about the SBR for treatment of swine manure and other types of wastewater provide valuable references for the treatment of dairy wastewater. However, due to the dif- ferences in the characteristics of dairy wastewater from other types of wastewater, research is needed to develop design and operational guidelines for the SBR in treating dairy wastewater of various characteri stics.The objectives of this study are to investigate the effects of wastewater characteristics, HRT, SRT, and organic loading rate on the performance of the SBR system in treating dairy wastewater for carbon and solids remov al and nitrogen conversion, and develop design and opera- tional guidelines for the SBR system in single- and mul- tiple-stage con fi gu rations.Each system was fed and decanted twice a day for 12 h in each treatment cycle. All the peristaltic pumps used for feeding and decanting were operated automatically with a digital time controller. The time sequence for differ ent operations during each treatment cycle of the SBR was1–3 min fill, 11 h and 4–8 min react, 40 min settle,1–3 min decant, and 10 min idle. The CMBR was op erated as a complete-mix reactor and had long SRT provided by the attached growth on the polyethylene pellets placed in the reactor. The plastic pellets had light density (920 kg/ m3) and were kept fluidized with the airflow. Each pellet was 10 mm in diameter and 10 mm in height, with a cross inside the cylinder and longitudinal fins on the outside, providing a large surface area for bacterial attac hment. The filling volume of the pellets in total occupied ap- proximately 18% of liquid volume (3 l) in the reacto r.The SBR and CMBR reactors were made from trans- parent acrylic and had a total volume of 6 l each, with 51 cm height and 12 cm diameter. During testing, the liquid vol- ume of each reactor was 3 l. Each reactor was aerated using pressurized air at a controlled flow rate. In order to min i- mize the water evaporation in the reactor, the air was hu- midified by traveling through water contained in a 15-l jar prior to entering the reactor. The air was evenly dis tributed into the wastewater through four air stone diffusers in- stalled near the bottom of the reactor. All the reactors wer e initially seeded with the activated sludge obtained from the UC Davis Wastewater Treatment Plant and allowed to ac- climate for about 2 months before formal experiments wer e started. It normally took about 4 weeks for each SBR re- actor to reach a steady state when a new operating condi- tion was introduced. The steady state was defined to be a state when the weekly variations of effluent COD, TS,NH3-N, and pH were less than 5%. These parameters w ere monitored twice a week. The CMBR had been fully accli- mated with dilute dairy wastewater for about 6 months and had nitrification bacteria well established before being connected with the SBR. The mixed liquor suspended solids (MLSS) in the CMBR was about 10,000 mg/l, which was calculated from both suspended growth and attached growth solids. In order to determine the ammonia emiss ion from SBR due to aeration, ammonia in the exiting air of SBR was collected by absorbing it in 0.3 N boric acid solution for 24 h under each testing condition.1042Materials and methods2.1Dairy manure collection and preparationDairy manure was collected on the Dairy Research Farm ofthe University of California at Davis. Due to runoff ofurine on the feedlot, the collected manure was mainly fecesand contained a relatively low content of ammonia nitro-gen. The manure was slurried with addition of water andthen screened twice with two sieves with openings of 4·4and 2·2 mm, respectively, to remove large particles. Thescreened manure was transported immediately to thelaboratory and stored in a freezer at –20 C until use. TheTS and COD of the screened manure were 30,000–40,000 mg/l and 35,000–50,000 mg/l, respectively. Whenneeded, the stored manure was thawed and then dilutedwith tap water to obtain a desired COD concentration. Dueto relatively low ammonia content of the raw manure ascompared to typical levels in the manure collected ondairy farms, urea was added to increase the NH3-N in theprepared manure from 100–125 mg/l to 500–550 mg/l. Theprepared manure was then put into a 50-l feeding tankhoused in a refrigerator at 4 C for daily use. The feedingtank had an agitator to mix the wastewater during thefeeding of the reactors.2.2Experimental setup and operationBoth single-stage and two-stage treatment systems were tested. The single-stage SBR system consisted of an SBR and a solids-settling tank in series. The wastewater was fi rst fed into the SBR for treatment and the effluent of the SBR, including both sludge and liquid, was then discharged into a settling tank, where liquid was separated from sludge by gravity settling and characterized as liquid effluent of the system. The two-stage system consisted of an SBR (fi rst- stage reactor), a solids-settling tank, and a complete-mix biofilm reactor (CMBR) (second-stage reactor) connected in series. The liquid effluent obtained from the solids-set- tling tank was used as influent of CMBR and further treated in the CMBR for achieving complete nitrification. The two- stage SBR-CMBR system is shown in Fig. 1. 2.3Experimental plan and system performance evaluation The experiment was carried out in two phases. The first phase was for studying the effects of influent characteris- tics, HRT, and corresponding SRT and loading rate on the performance of the single-stage SBR system. The se cond phase was to evaluate the performance of a two-stage SBR- CMBR system. The two systems were then compared in terms of carbon and solids removal and nitrogen conver- sion efficiencies.With the single-stage SBR system, three HRTs (1, 2 and 3 days) were tested for wastewater of 10,000 mg/l COD and four HRTs (1, 2, 3 and 4 days) for wastewater of20,000 mg/l COD. For the wastewater of 10,000 mg/l COD, the corresponding loading rate and SRT for the three HRTs were 10, 5, and 3.3 g COD/l/day and 8, 12, andX. Li, R. Zhang: Aerobic treatment of dairy wastewater with sequencing batch reactor systems105Fig. 1. Laboratory setup for a two-stageSBR-CMBR system for dairy wastewatertreatment15 days, respectively. For the wastewater of 20,000 mg/l COD, the corresponding loading rate and SRT for the four HRTs were 20, 10, 6.7, and 5 g COD/l/day and 1.5, 3, 4, and 6 days, respectively. With the two-stage SBR system,2 days was used first as the system HRT, with 1 day for the first-stage and 1 day for the second-stage for both in fl u- ents, and then 2.5 days was used with 2 days for the fi rst stage and 0.5 days for the second stage. An airflow rate of 4 l/min was applied for all runs, which was able to main- tain dissolved oxygen (DO) in the SBR and CMBR ab ove3 m g/l.The performance of the treatment systems was evalu- ated in terms of carbon and solids removal and nitrogen conversion efficiencies. The parameters analyzed included TS, volatile solids (VS), COD, SCOD (soluble COD), TKN, NH3-N, NO2-N, and NO3-N. Two kinds of removal/con- version efficiencies were used to interpret the results for carbon and solids removal and nitrogen oxidation. One efficiency, E t, is based on the removal from total ef fl uent (including both sludge and liquid effluent generated), re- flecting the removal efficiency through biological proc ess alone. The other efficiency, E l, was based on the remov al from liquid effluent, i.e., supernatant, representing the removal efficiency through both biological process and sludge separation. For the single-stage SBR system, the total effluent was the effluent from the SBR and the liquid effluent was the supernatant decanted from the solids settling tank. For the two-stage SBR-CMBR system, the total effluent was the combination of sludge from the settling tank and the final effluent from CMBR, and the liquid effluent was the liquid effluent of CMBR. Most of previous research only reports removal efficiency from liquid effluent (E l). Actually, E l does not reflect the real capability of a system for removing various con stituents from wastewater, because part of these constituents are contained in the sludge that is separated from the liq uid effluent and discharged as a separate sludge stream. Therefore, E t needs to be used in order to assess the rea l capability of a system for removing various con stituents from wastew ater.2.4Sampling and analytical methodsAfter each reactor reached steady state under testing conditions, samples were taken from the influent, m ixe d liquor, total effluent, and liquid effluent of the reacto r three times a week (every other day) for analyses of COD, SCOD, TS, VS, NH3-N, NO2-N, NO3-N, and TKN. The re- moval efficiencies, E l and E t, were calculated based on the data from influent, liquid effluent, and total effluent of the systems. The separation of sludge and liquid in the total effluent of the SBR was performed by settling the ef fl uent in a 1-l graduated cylinder for 2 h and then decanting the liquid fraction above the sludge-liquid interface line.The COD, SCOD, TS, VS, and TKN were m easured according to APHA standard methods [11]. The COD measured in this study was COD Cr. The pH was m eas ured with an Accumet pH meter (Fisher Scientific, Pittsbu rgh, Pa.). The NH3-N was measured with a gas-sensing elec- trode and the pH meter. The DO in the reactors was monitored on a daily basis with a DO meter (YSI Mode158, Fisher Scientific, Pittsburgh, Pa.). The NO2-N was anal yzed with the HACH method, using a DR/2000 spectro pho- tometer [12]. The NO3-N was measured with a diffusi on–conductivity analyzer [13].3Results and discussion3.1Performance of the single-stage SBR system3.1.1Removal of carbon and solidsThe performance data of the SBR for 10,000 mg/l COD influent COD of 10,000 are shown in Table 1. With the increase of HRT from 1 to 3 days, the COD, SCOD, TS, and VS in the liquid effluent became lower, yielding bet ter effluent quality due to increased biological conversion and improved sludge settleability, as indicated by the incr eased removal efficiencies (E l and E t). However, there was noBioprocess Biosyst Eng 25 (2002)Table 1. Effluent quality and treatment efficiencies of SBR for 10,000 mg/l COD in fl uentParameters In fl uent(mg/l)1-day HRT 2-day HRT 3-day HRTLiquid ef fl uent (mg/l)Totalef fl uent(mg/l)E l(%)E t(%)Liquidef fl uent(mg/l)Totalef fl uent(mg/l)E l(%)E t(%)Liquidef fl uent(mg/l)Totalef fl uent(mg/l)E l(%)E t(%)COD SCOD TS VS TKN TN NH3-N NO3-N NO2-N pH 10,0002,9146,6565,1087807805108.11,9801,4572,4361,724195481120372496.86,5001,4575,2323,36136560712080.250.063.466.27538.376.545.050.021.434.253.222.276.51,5801,4512,4761,532185480105552406.75,1301,4515,0793,24935459810584.250.262.870.076.338.579.448.750.223.736.454.623.479.41,4701,4282,4161,40016547470452806.74,9301,4285,0983,1673385967085.351.063.772.678.839.286.350.751.023.438.056.723.686.3106significant difference in terms of carbon and solids rem-ovals and liquid effluent quality for the three HRTs. For example, the increase of COD and TS removal efficiency E l was 5.1% and 0.3%, and E t was 5.7% and 2.0%, respe c- tively, when HRT increased from 1 to 3 days. Therefo re, 1-day HRT was believed to be sufficient for treating the dairy wastewater with 10,000 mg/l COD for its satisfactory removal efficiency and relatively short HRT. At 1-day HRT, the removal efficiency from the liquid effluent (E l) was 80.2% for COD, 63.4% for TS, and 66.2% for VS. T hese removals were due to both biological conversion in the SBR and sludge separation in the solids-settling tank. The removal due to biological conversion alone in the SBR, as measured by E t, was 45.0% for COD, 21.4% for TS, and 34.2% for VS. E t was significantly greater than E l, sug- gesting that the sludge separation after SBR treatment is necessary for achieving significant carbon and solids re- moval from the dairy wastewater. It was found that aerobic treatment greatly enhanced the flocculation and settlea- bility of the solids in the wastewater. Good settleability of sludge was important for achieving high carbon and solids removal efficiency.The performance data of the SBR for 20,000 mg/l COD influent are shown in Table 2 . The 1-day HRT was tested first. It was found that it was impossible to control the SRT at a desired level due to fast solids buildup in the reactor and poor solids settleability. When the HRT was increased to2 days, there was significant improvement in the ef fl uent quality and increase of removal efficiencies. However, when the HRT was further increased to3 days, the changes in the effluent quality, COD, and solids removals were not signif- icant. Therefore, 2-day HRT was considered enough for COD and solids removal for 20,000 mg/l COD influent due to its relatively short retention time and high removal effi- ciency. At 2-day HRT, the removal efficiency E l of COD, SCOD, TS, and VS was 85.7%, 67.1%, 71.0%, and 70.6%, respectively, and E t was 35.9%, 67.1%, 22.8%, and 25.6%, respectively. The 4-day HRT was tested for achieving com- plete ammonia conversion. Since ammonia was not com- pletely converted at 2-day and 3-day HRT, longer HRT was needed when complete nitrification was desired. This will be further discussed in the following nitrogen removal se ction.The sludge separated from the effluent of the SBR contained 4.1–5.9% TS. The lower influent COD(10,000 mg/l) resulted in better sludge settleability than the higher influent COD (20,000 mg/l). The sludge volum e as the fraction of total effluent volume was 5–6% and13–16% for the lower and higher levels of influent COD, respectively. The sludge was composed of not-degrad ed solids in the wastewater and newly formed bacterial cells. It can be further processed into organic soil amendm ent through dewatering and composting.Table 2. Effluent quality and treatment efficiencies of SBR for 20,000 mg/l COD in fl uentPara-meters Influent 1-day HRT 2-day HRT 3-day HRT 4-day HRT(mg/l)Liquidef fl uent(mg/l)Totalef fl uent(mg/l)E l(%)E t(%)Liquidef fl uent(mg/l)Totalef fl uent(mg/l)E l(%)E t(%)Liquidef fl uent(mg/l)Totalef fl uent(mg/l)E l(%)E t(%)Liquidef fl uent(mg/l)Totalef fl uent(mg/l)E l E t(%) (%)COD SCOD TS VS TKN TN NH3-N NO3-N NO2-N pH 20,0006,66012,44210,1041,1401,1405408.04,3003,1974,3673,14254057331020138.713,9203,19710,1157,92289993331078.552.064.968.952.649.742.630.452.018.721.621.118.242.62,8702,1903,6122,972180484821641407.912,8202,1909,6057,5176389188285.767.171.070.684.257.584.835.967.122.825.644.019.584.82,6602,0053,4982,809170488801881307.812,3202,0059,5807,3366009188086.769.971.972.285.157.285.238.469.923.027.447.419.585.2167012153350246085388293107.610,9001,2159,1957,05350088891.781.873.175.792.563.043.381.824.329.552.320.5100 100X. Li, R. Zhang: Aerobic treatment of dairy wastewater with sequencing batch reactor systems3.1.2Nitrogen conversionWith the influent of 10,000 mg/l COD and 1- to 3-day HRT, 22.2–23.6% of total nitrogen (TN) was lost in the treatment process as indicated by the E t. The losses of TN for the three HRTs were not significantly different. The ammonia collection results showed that the amount of NH3-N volatilized accounted for only 2–3% of TN, indi- cating that the ammonia loss through volatilization was small under these operating conditions. The rest of TN loss (approximately 20%) might be due to the emission of other nitrogenous gases, such as nitrous oxides (NO and NO2) formed in the nitrification process, and nitrogen gas (N2) formed in the denitrification process. The TKN removal was 53.2–56.7% from the total effluent and 75–78.8% from the liquid effluent, respectively. The TKN removal mainly resulted from ammonia oxidation.With the influent of 20,000 mg/l COD and 1- to 4-day HRTs, the loss of TN was 18.2–20.5%. For the 1-day HRT, the ammonia collection results showed that ammo nia volatilization accounted for 16% of TN, indicating that most of TN loss was due to ammonia volatilization. This occurred with the low nitrification rate in the SBR. But ammonia volatilization was insignificant at 2- to 4-day HRTs, at which the SBR had high nitrification activities. These results might imply that ammonia volat ilization could be related to nitrification activity. Little nitri fi cation occurrence at 1-day HRT was due to the short SRT of 1.5 days. This agrees with the findings of Prakasam and Loehr [14], who stated that 2-day SRT was the minimum for nitrification of poultry wastes. Therefore, HRT was increased to 2 days and 3 days, and corresponding SRT were 3 days and 4 days. It was found that nitrification was able to sustain in the SBR at both HRTs. At 2-day and3-day HRT, the TN and TKN removals were 19.5% and 44.0–47.4% from the total effluent, and 57.5–57.2% and 84.2–85.1% from the liquid effluent, respectively. Signi fi ca ntNH3-N was removed, as indicated by removal efficiency of 84.8% for 2-day HRT and 85.2% for 3-day HRT, although there was still 80–82 mg/l residual NH3-N present in the effluent. It can be seen that there was no significant dif- ference between two HRTs in terms of TN, TKN, and NH3- N removal. Therefore, if complete ammonia oxidation is not required, 2-day HRT would be considered efficient for treating 20,000 mg/l COD influent in terms of both nitrogen removal discussed here and COD and solids removal as mentioned in Sect. 3.1.1.Certain amounts of residual ammonia were present in the effluent from 20,000 mg/l COD influent at 2-day and 3-day HRT. This indicates that the nitrification proc ess might have been inhibited in both operation conditions. Nitrification inhibition might be due to possible inhib itions of nitrification bacteria by free ammonia (FA) and fre e nitrous acids (FNA) and suppression of nitrification bac- teria by more competitive heterotrophic bacteria [15]. NH3 was undesirable because of its odor and toxicity to aquati c lives; thus, it needed to be removed from the wastewater. Shammas [16] studied the interaction of temperature, pH, and biomass on the nitrification process and concluded that high nitrification efficiency can only be obtained with either very long detention time or a combination of highsolids concentration and elevated temperature. Therefo re,HRT was further increased to 4 days in order to obtain complete ammonia conversion. It was found that 4-dayHRT, corresponding 6-day SRT, was enough for compl ete ammonia conversion, as indicated by zero ammonia pre-sent in the effluent (see Table 2). Therefore, it could be concluded that if complete ammonia conversion is d e sired,4-day HRT would be needed for treating 20,000 mg/l COD wastewater with 540 mg/l NH3-N.A track study was conducted in order to further un-derstand the nitrification process in the SBR. The varia-tions of NH3-N, NO2-N, and NO3-N in the SBR during a12-h operating cycle in treating the wastewater of10,000 mg/l COD at 2-day HRT are shown in Fig. 2. A m-monia oxidation mostly occurred in the first 5 h, as indi-cated by the increase of NO2-N and decrease of NH3-N.Since a large amount of ammonia was oxidized in the ear lystage of one cycle with high nitrification, the amount of ammonia volatilization may be decreased in contrast tothe condition when nitrification is small as men tionedabove. The relationship between ammonia volatiliza tionand nitrification activity needs to be further investigated infuture study. The pH could be another factor related to ammonia volatilization. Since higher medium pH in-creased the gas fraction of total ammonia dissolved in the medium, ammonia volatilization could have been highwhen there was little nitrification and pH maintained rel-atively high (approximately 8.0), but small when there wasgood nitrification and the pH was decreased (Fig. 2). TheNO2-N increased to the peak value about 5 h later afterfeeding and then started to decrease, while NO3-N startedto increase slightly. Generally speaking, the variations ofNH3-N, NO2-N, NO3-N, and pH in the SBR during the operating cycle depends on the bioconversion dynamics inthe reactor, initial ammonia concentration, and alkal inityin the w astewater.1073.2Performance of the two-stage SBR-CMBR systemAs stated above, a 4-day HRT is needed for achievingcomplete oxidation of ammonia in the dairy wastewater inFig. 2. Profiles of NH3-N, NO2-N, NO3-N and pH in a cycle of theSBR with 2-day HRT and 10,000 mg/l COD in fl uentBioprocess Biosyst Eng 25 (2002)nitrification. Since carbon could be oxidized quickly by fast-growing heterotrophic bacteria, the first-stage rea ctorcould use a relatively shorter HRT. After the fi rst-st age SBR treatment, the solids settleability is improved as well, the sludge generated is separated and the liquid effluent is used as influent for the second-stage reactor. Sludge sep- aration would significantly increase the system remov al efficiency and reduce concentrations of constituents such as COD, TS, and NH 3-N in the influent, making it possibl e to use a shorter HRT, while maintaining a longer SRT for nitrification in the second-stage reactor. With the opti- mization of environmental conditions and substratecharacteristics for heterotrophic and autotrophic bacteria in separate stages as mentioned above, the overall pe r- formance of the two-stage system can be improved and overall HRT reduced, as indicated from the performance data presented below.The two-stage system consisted of one SBR as the fi rst stage and one CMBR as the second stage. The CMBR was selected to be the second-stage reactor, because the at- tached bacteria growth supported by the polyethylene pellets were believed to be favorable for nitrification bac - teria by providing a long SRT. The CMBR was used to treat the liquid effluent from the SBR. Both SBR and CMBR were first operated at 1-day HRT, with the system HRT being 2 days for treating 10,000 mg COD/l and 20,000 mg COD/l influent, respectively. The 1-day HRT in the CMBR was determined to be the appropriate level, based on preliminary test results. The performance data of the two - stage system are shown in Tables 3 and 4. It can be seen that the liquid effluent quality and removal efficiencies of carbon, solids, and nitrogen from the two-stage system at 2-day HRT were comparable to those from the single-stage SBR at 3-day HRT for both influents. This suggests that, based on the HRT, the two-stage system would require 1/3 less reactor volume than the single-stage system and therefore appears to have more favorable economics. In addition, the two-stage system allows complete ammonia oxidation in the wastewater as indicated by zero NH 3-N present in the two-stage system effluent at 2-day HRT a s compared to 70 mg/l NH 3-N in the one-stage effluent at 3-day HRT.Because with the influent of 20,000 mg/l COD ammonia volatilization was high in the first-stage SBR at 1-day HRT,Table 3. Performance of two-stage SBR-CMBR system for 10,000 mg/l COD in fl uent In fl uent(mg/l) Stage I: SBR(1-day HRT) Liquid ef fl uent (mg/l) Stage II: CMBR (1-day HRT) Liquid ef fl uent (mg/l ) E l (%) E t(%) COD SCOD TS VS TKN TN NH 3-N NO 3-N NO 2-N pH10,000 2,914 6,656 5,108 780 780 510 0 0 8.1 1,980 1,457 2,436 1,724 195 481 120 37 249 6.81,374 1,014 2,076 1,472 60 435 2.5 195 180 7.986.3 65.2 68.8 71.2 92.3 44.2 99.551.1 65.2 24.8 39.1 58.0 24.7 99.5108the single-stage SBR. It appears that increasing HRT toachieve complete nitrification is not cost effective. This led us to explore a two-stage treatment system. Research showed that nitrifying in a separate second-stage aer ation system would increase nitrification rate, due to the more suitable environment provided by a two-stage system than a single-stage system [17]. In aerobic treatment, carbon oxidation is carried out by heterotrophic bacteria, while nitrification is carried out by autotrophic bacteria. The two groups of bacteria are significantly different in physiolo gy, substrate requirement, metabolic characteristics, and growth kinetics. In a single-stage system, both carb on oxidation and nitrification proceed in one reactor. This forces two groups of bacteria to coexist within the sam e physical and chemical environment, which is not optim al for either autotrophic or heterotrophic bacteria and ma kes it difficult to achieve optimum carbon and ammonia conversion. Usually, longer HRT is applied in a single- stage system to balance the slow-growing autotroph ic bacteria responsible for nitrification and fast-growing he- terotrophic bacteria for carbon oxidation. But this is not economical, as mentioned above. A two-stage system could separate carbon oxidation and the nitri fi catio n process and make each process proceed in a separate re- actor. The first-stage reactor is intended mainly for carbon oxidation and enhancement of solids settleability, and the second-stage reactor for providing suitable conditions forTable 4. Performance of the two-stage SBR-CMBR system for 20,000 mg/l COD in fl uent In fl uent (mg/l)stage I: SBR (1-day HRT) Liquid ef fl uent (mg/l) stage II: CMBR (1-day HRT) Liquid ef fl uent (mg/l ) E l (%) E t (%)stage I: SBR (2-day HRT) Liquid ef fl uent (mg/l) stage II: CM BR (0.5-day HRT) Liquid ef fl uent (mg/l) E l (%) E t (%)COD SCOD TS VS TKN TN NH 3-N NO 3-N NO 2-N pH20,0006,660 12,442 10,104 1,140 1,140 540 0 0 8.04,300 3,197 4,367 3,142 540 573 310 20 13 8.72,676 2,020 3,432 2,152 180 504 3.0 190 134 7.886.6 69.7 72.4 78.7 84.2 55.8 99.4 37.0 69.7 21.8 27.0 46.1 23.2 99.4 2870 2190 3612 2972 180 484 82 164 140 7.91100 890 2670 1060 40 430 0 390 0 7.494.5 86.6 78.5 89.5 96.5 62.3 100 43.8 86.6 26.4 32.5 56.2 21.5 100。
中英文文献以及翻译(化工类)
Foreign material：Chemical Industry1.Origins of the Chemical IndustryAlthough the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin’s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939).Since 1940 the chemical industry has grown at a remarkable rate, although this has slowed significantly in recent years. The lion’s share of this growth has been in the organic chemicals sector due to the development and growth of the petrochemicals area since 1950s. The explosives growth in petrochemicals in the 1960s and 1970s was largely due to the enormous increase in demand for synthetic polymers such as polyethylene, polypropylene, nylon, polyesters and epoxy resins.The chemical industry today is a very diverse sector of manufacturing industry, within which it plays a central role. It makes thousands of different chemicals whichthe general public only usually encounter as end or consumer products. These products are purchased because they have the required properties which make them suitable for some particular application, e.g. a non-stick coating for pans or a weedkiller. Thus chemicals are ultimately sold for the effects that they produce.2. Definition of the Chemical IndustryAt the turn of the century there would have been little difficulty in defining what constituted the chemical industry since only a very limited range of products was manufactured and these were clearly chemicals, e.g., alkali, sulphuric acid. At present, however, many intermediates to products produced, from raw materials like crude oil through (in some cases) many intermediates to products which may be used directly as consumer goods, or readily converted into them. The difficulty cones in deciding at which point in this sequence the particular operation ceases to be part of the chemical industry’s sphere of activities. To consider a specific example to illustrate this dilemma, emulsion paints may contain poly (vinyl chloride) / poly (vinyl acetate). Clearly, synthesis of vinyl chloride (or acetate) and its polymerization are chemical activities. However, if formulation and mixing of the paint, including the polymer, is carried out by a branch of the multinational chemical company which manufactured the ingredients, is this still part of the chemical industry of does it mow belong in the decorating industry?It is therefore apparent that, because of its diversity of operations and close links in many areas with other industries, there is no simple definition of the chemical industry. Instead each official body which collects and publishes statistics on manufacturing industry will have its definition as to which operations are classified as the chemical industry. It is important to bear this in mind when comparing statistical information which is derived from several sources.3. The Need for Chemical IndustryThe chemical industry is concerned with converting raw materials, such as crude oil, firstly into chemical intermediates and then into a tremendous variety of other chemicals. These are then used to produce consumer products, which make our livesmore comfortable or, in some cases such as pharmaceutical produces, help to maintain our well-being or even life itself. At each stage of these operations value is added to the produce and provided this added exceeds the raw material plus processing costs then a profit will be made on the operation. It is the aim of chemical industry to achieve this.It may seem strange in textbook this one to pose the question “do we need a chemical industry?” However trying to answer this question will provide(ⅰ) an indication of the range of the chemical industry’s activities, (ⅱ) its influence on our lives in everyday terms, and (ⅲ) how great is society’s need for a chemical industry. Our approach in answering the question will be to consider the industry’s co ntribution to meeting and satisfying our major needs. What are these? Clearly food (and drink) and health are paramount. Other which we shall consider in their turn are clothing and (briefly) shelter, leisure and transport.(1)Food. The chemical industry makes a major contribution to food production in at least three ways. Firstly, by making available large quantities of artificial fertilizers which are used to replace the elements (mainly nitrogen, phosphorus and potassium) which are removed as nutrients by the growing crops during modern intensive farming. Secondly, by manufacturing crop protection chemicals, i.e., pesticides, which markedly reduce the proportion of the crops consumed by pests. Thirdly, by producing veterinary products which protect livestock from disease or cure their infections.(2)Health. We are all aware of the major contribution which the pharmaceutical sector of the industry has made to help keep us all healthy, e.g. by curing bacterial infections with antibiotics, and even extending life itself, e.g. ß–blockers to lower blood pressure.(3)Clothing. The improvement in properties of modern synthetic fibers over the traditional clothing materials (e.g. cotton and wool) has been quite remarkable. Thus shirts, dresses and suits made from polyesters like Terylene and polyamides like Nylon are crease-resistant, machine-washable, and drip-dry or non-iron. They are also cheaper than natural materials.Parallel developments in the discovery of modern synthetic dyes and the technology to “bond” th em to the fiber has resulted in a tremendous increase in the variety of colors available to the fashion designer. Indeed they now span almost every color and hue of the visible spectrum. Indeed if a suitable shade is not available, structural modification of an existing dye to achieve this canreadily be carried out, provided there is a satisfactory market for the product.Other major advances in this sphere have been in color-fastness, i.e., resistance to the dye being washed out when the garment is cleaned.(4)Shelter, leisure and transport. In terms of shelter the contribution of modern synthetic polymers has been substantial. Plastics are tending to replace traditional building materials like wood because they are lighter, maintenance-free (i.e. they are resistant to weathering and do not need painting). Other polymers, e.g. urea-formaldehyde and polyurethanes, are important insulating materials f or reducing heat losses and hence reducing energy usage.Plastics and polymers have made a considerable impact on leisure activities with applications ranging from all-weather artificial surfaces for athletic tracks, football pitches and tennis courts to nylon strings for racquets and items like golf balls and footballs made entirely from synthetic materials.Like wise the chemical industry’s contribution to transport over the years has led to major improvements. Thus development of improved additives like anti-oxidants and viscosity index improves for engine oil has enabled routine servicing intervals to increase from 3000 to 6000 to 12000 miles. Research and development work has also resulted in improved lubricating oils and greases, and better brake fluids. Yet again the contribution of polymers and plastics has been very striking with the proportion of the total automobile derived from these materials—dashboard, steering wheel, seat padding and covering etc.—now exceeding 40%.So it is quite apparent even from a brief look at the chemical industry’s contribution to meeting our major needs that life in the world would be very different without the products of the industry. Indeed the level of a country’s development may be judged by the production level and sophistication of its chemical industry4. Research and Development (R&D) in Chemical IndustriesOne of the main reasons for the rapid growth of the chemical industry in the developed world has been its great commitment to, and investment in research and development (R&D). A typical figure is 5% of sales income, with this figure being almost doubled for the most research intensive sector, pharmaceuticals. It is important to emphasize that we are quoting percentages here not of profits but of sales income, i.e. the total money received, which has to pay for raw materials, overheads, staff salaries, etc. as well. In the past this tremendous investment has paid off well, leading to many useful and valuable products being introduced to the market. Examplesinclude synthetic polymers like nylons and polyesters, and drugs and pesticides. Although the number of new products introduced to the market has declined significantly in recent years, and in times of recession the research department is usually one of the first to suffer cutbacks, the commitment to R&D remains at a very high level.The chemical industry is a very high technology industry which takes full advantage of the latest advances in electronics and engineering. Computers are very widely used for all sorts of applications, from automatic control of chemical plants, to molecular modeling of structures of new compounds, to the control of analytical instruments in the laboratory.Individual manufacturing plants have capacities ranging from just a few tones per year in the fine chemicals area to the real giants in the fertilizer and petrochemical sectors which range up to 500,000 tonnes. The latter requires enormous capital investment, since a single plant of this size can now cost $520 million! This, coupled with the widespread use of automatic control equipment, helps to explain why the chemical industry is capital-rather than labor-intensive.The major chemical companies are truly multinational and operate their sales and marketing activities in most of the countries of the world, and they also have manufacturing units in a number of countries. This international outlook for operations, or globalization, is a growing trend within the chemical industry, with companies expanding their activities either by erecting manufacturing units in other countries or by taking over companies which are already operating there.化学工业1.化学工业的起源尽管化学品的使用可以追溯到古代文明时代，我们所谓的现代化学工业的发展却是非常近代（才开始的）。
环境工程、给排水专业外文参考文献译文
浮选柱处理含油废水的研究摘要：本文介绍了一种为处理含油废水而开发的新型溶气浮选柱装置。
溶气浮选柱将溶气气浮法和浮选柱巧妙的加以结合运用，溶解空气在柱体分离系统中释放。
本文对这种具有潜在应用价值的柱体系统分离含油废水中油分的效果进行了研究，在一系列的实验中该装置均取得了理想的分离效果，同时还对溶气浮选柱中采用的气泡产生器的曝气效果进行了专门研究。
关键词：含油废水；分离；气浮；气泡发生器；溶气浮选柱一、引言含油废水是石油开发利用过程中产生的面积广，数量大的污染源。
废水中的油分包括浮油，分散油，乳化油，溶解油和油-固结合物。
含油废水常用的处理技术有物理法、物理化学法、化学破乳法、生物化学法和电化学法。
分离难易程度取决于油分在水体中的存在形式。
含油废水中的浮油一般可以采用重力分离技术予以去除，溶解油可以通过生物处理法将其去除，而以胶体状态存在的分散油和乳化油由于其平均粒径小，化学稳定性高而难以去除。
近年来，浮选技术由于具有分离效率高，资金投入少，运行费用低的特点而吸引了众多学者的关注，并且已经开发出一些新型的快速高效的含油废水处理装置。
Feng P B 和其合作者开发出一种高效节能浮选柱进行含油废水处理，其油分的去除率可以达到90%左右。
Gu Xuqing等人开发出一种新型多级环流式浮选柱可处理含油废水，其独特的流体环流模式极大的提高了油珠和气泡之间的接触几率，分离效果显著，5分钟，分离效率可以达到96%-97%。
Xiao K L等人用多级浮选柱处理含油废水，空气分散在装置的柱体托盘底部，含油废水在柱体的各个托盘中进行处理，除油率达94%。
含有乳化油的废水处理较为困难，为保证浮选效率，分离时要求气泡粒径小，并且在分离区域中形成安静的水力学环境。
分离区应当又长又窄这一概念引发了利用柱状体作为分离设备这一设计理念。
由此产生了一种叫做溶气浮选柱的新型设备，溶解空气在该装置的柱体分离系统中析出，以此来处理含油废水。
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附录1外文翻译Journal of Environmental Sciences.2005,17（4）: 681—685用固定化反应器快速处理制革废水中难解有机及无机废物A. Ganesh Kumar, G. Sekaran , S. Swarnalatha ,B. Prasad Rao摘要：tannerie县排放的污水因难降解化合物存在，缺乏生物降解能力。
本次调查利用化学自养活性炭氧化反应堆（CAACO），即一个固定化细胞反应器培养自营菌处理制革废水。
处理方案包括厌氧处理，砂滤，并经CAACO反应堆处理化学需氧量，生化需氧量，总有机碳，挥发性脂肪酸和硫化物，降解率分别为86％，95％，81％，71％和100％。
生化槽中多孔活性炭用于固定化合自营菌。
难生物降解的化合物经CAACO处理后，用高效液相色谱法和红外光谱技术检测。
关键词：化学自养活性碳氧化反应槽内消多孔渗水介质废水处理异生化合导言：人造化合物用于复鞣工艺处理皮革抗微生物攻击和承受热冲击。
尽管他们被归入有机化合物，他们缺乏的生物降解法由于其毒性性质多样性，因此可将其分布在厌氧/好氧反应器的废水处理设施（洛赫尔，1991年）。
有机合成化学品在鞣制使用过程中，如磺化单，双和三核芳烃，磺化azoaromatic化合物，硫酸或sulphited 长链脂肪酸等在废水中逸出的主要由化学处理和二级生物处理单元操作解决（Reemtsma ，1993年，1995年）。
大多数这些化合物可以抵制生物降解，因为这些化合物的代谢产物或其衍生产品是有毒的微生物（冈田，2000年）。
这些化合物主要是致癌，诱变和致畸的性质。
有毒有机物性质由于其倾向灭活生物体可以通过吸附在细胞膜的方法（雨果，1977年），这可以防止它合成外细胞聚合物或诱导细胞壁破裂。
该化合物因难被微生物降解被称为生物难分解或异化合物。
那个溶解异化合物往往可以增加对替代磺酸芳香原子核分子。
因此，这种化合物可以逃避厌氧/好氧生物处理使得细菌培养被迫暂停。
然而，将其固定在合适的运载菌可以显示出在降低难降解有机物对那些处在暂停状态的细菌几个方面的优势。
这一过程的研究中使用的固定组成主要有chemoautotrophs芽孢杆菌。
在孔活性炭中，装在一个核反应堆称为化疗自活性炭氧化（CAACO）。
激活已被选定为反应床材料的反应堆因其巨大的吸附表面力和结构合适辅助材料的微生物，也可提供高吸附能力的有机化合物。
那个活性炭有粗糙的表面和孔隙裂隙，这些微生物能够解决难分解问题（Morsen，1990年）。
活性炭填充床反应器能够有效地降解高浓度废水（罗伦佐，2004年）。
因此，目前的首要目标调查研究的功效chemoautotrophs 固定化槽活性炭迅速彻底清除顽固或异化合物制革废水。
1材料与方法本文中这些样本的废水排放是从制革厂通过CAACO反应器处理后，通过初级澄清和厌氧处理系统。
1.1活性炭制备及特性选定的稻杆材料precarbonized在400℃，4小时的速度在10 ℃每分钟下减少温度中进行的。
碳的precarbonized当时受到化学活化作用必须使用氢酸作为活化剂。
那个化学活化剂碳化碳比定为4.2 。
由此产生的混合物被激活立式圆筒炉是在800℃下控制条件中进行的。
1.2化疗自活性炭氧化（CAACO）反应堆，该CAACO反应堆已取代传统的生物污水处理系统，由于其较高的处理效率和生态影响小。
在运行中孔活性炭的高度9.26厘米填补了粗笊篱的高度5厘米。
所需的氧化废水中的氧气是有机物提供的，空气压力5 kg/cm2下通过空气扩散放在反应床粗滤网。
该CAACO反应堆的体积720立方厘米有内部直径5.5厘米和有效碳床体积220立方厘米是该项研究中所用。
流程图由单位业务厌氧沼气池，砂滤和CAACO用于治疗制革废水。
这两个厌氧消化和砂滤被认为是预处理步骤CAACO进程。
厌氧沼气池改善物理清除悬浮固体和高度提高了生物转化。
在砂滤去除悬浮固体颗粒的废水。
那个出水后，砂滤处理的CAACO反应堆。
这些消化和过滤过程有助于转变的有机或无机污染物环境可接受的氧化/还原过程。
预处理后的制革废水的步骤是馈入CAACO在向下流动。
氧气/ COD的比值入口在CAACO保持在1.0 。
（图略）1.3化学分析制革废水处理通过从初级池，厌氧处理，CAACO，是分析化学氧化需氧量（COD），有机碳总量（目录），生物氧化的需求（生化需氧量），挥发性脂肪酸酸（挥发性脂肪酸），pH值使用标准的方法（Clesceri ，1989年）。
崩溃的污染物被确认通过高高效液相色谱法（HPLC）和傅立叶变换红外光谱（FT - IR ）。
1.4表面形貌表面形貌进行，样本中孔活性炭和化合自迎菌固定化介孔碳使用低轨Jeol 扫描电子显微镜后，涂有金黄金溅射设备。
1.5傅里叶变换红外光谱（红外）出水样品之前和之后CAACO治疗真空状态下被干燥的残留颗粒在压力约1兆帕级的光谱与红外光谱。
表面官能团进行了分析，以确定改变使用运输署埃尔默红外光谱仪。
1.6高效液相色谱法（HPLC ）出水样本量50毫升之前和之后CAACO治疗离心去除粗固体和干在玻璃坩埚真空。
完全干燥后，免费样品的水分，然后提取甲醇和筛选。
经过筛选的样本注入沉包C18分析列使用甲醇：水（50:50）为流动相，以流速为1毫升/分钟的高效液相色谱仪检测。
2结果与讨论2.1特性碳碳的特点表明，碳的百分比是48.45和它的脱色力22毫克/克这得到了低碳钢面积220平方米/ g和毛孔都在孔范围。
2.2催化氧化的制革废水污水经过初级处理，厌氧治疗和CAACO治疗进行了分析化学污染参数。
BOD / COD的比值未经处理的废水可生化指标的措施废水为0.31表明，废水少服从污水生物处理。
贫生物降解的废水是由于存在单，双和三核磺化芳香族化合物在废水。
该COD/SO42-比值废水中的范围为2.0 -2.7 ，如此高的比例不赞成甲烷生存不是硫酸盐还原菌（储）更喜欢在无氧环境（埃尔克，1996年;镜头，1998年）。
自由能由发酵有机化合物使用硫酸盐作为电子受体，形成硫化物不是甲烷，作为最终产品得多更青睐（Kjeld ，2003年）。
这是显而易见的特点废水排放从上流式厌氧泻湖的拘留时间2.8天。
表明，硫化物含量厌氧废水增加了188 ±47毫克/升以上的主要治疗废水和硫酸含量的厌氧废水下降到1113 ±199 mg / L时为965 ± 190毫克/升那个同样的结果还观察到马蒂亚斯，显示有机和无机硫化合物转换硫化物在厌氧处理的污水（马蒂亚斯，1998年）。
厌氧消化过程中的硫酸盐，丰富的硫化物生产废水（布兰迪斯，1981年; Ingvorsen ，1984年）和一小部分（f ）的总硫化物生产中保留水相的可溶性形式和剩余硫化物（ 1 - 女）占用气相形式的氢硫化物。
分数硫化物，它存在于水相作为一个功能的pH 值是由表达。
表1特性的碳基催化剂样品编号参数值1 2 3 4 5 6 7 8 9101112131415 碳氢氮灰粉含量容重水分含量灰分含量水溶物易溶于酸性物质pH脱色力苯酚含量离子交换力面积比孔径m48.45%0.7%0.1%51.8%0.405g/ml3.8%40%质量0.428%3.908%6.6622mg·g3.18mg/g0.015mg/g220m2//g20×10-10f= [ 1 + K/10(-pH)](-1)（1）凡K的速率常数。
该浓度的硫化氢气体中相是由（硫化氢）g= （1 -f）× Saq (2-)/α（2）α是海伦常数，1.7。
表2特征制革废水在不同阶段的治疗样本编号参数值1 pH值2化学需氧量mg/L 3生化需氧量mg/L 4铬mg/L5硫化氢mgPL6硫酸mg/L7挥发性脂肪酸mg/L 8碳酸氢铵mg/L 原料5.49 ±0.723260 ± 9601013 ± 3471235 ± 41120 ± 2.31206±4021180 ± 368211 ± 146初级净化10.82±0.661920± 509689 ± 171735 ± 20012 ± 4.91113 ± 1991363 ± 354100 ± 45厌氧处理7.8 ± 0.531820± 448412 ± 127673 ± 143188 ± 47965 ± 190609 ± 202627 ± 246CAACO处理7.2± 0.61471 ± 9952 ± 18239 ± 56728 ± 90338 ± 89160 ± 73减少百比-85.594.980.610039.671.424.2表3中的数据质量平衡中的硫厌氧消化处理制革废水。
的代数和硫化物在水相和硫化物的气相使生产总硫化物（195毫克/升）。
预期硫酸盐含量废水厌氧处理后的之间的区别主要澄清硫酸废水和硫酸相当于硫化物代（1113年- 585 = 528 mg / L时）。
代数区别实际和预计硫酸盐含量后的废水厌氧发酵（965-528 = 437mg/L时）显示，有一个新一代的范围从硫酸磺化有机化合物在厌氧消化。
大幅度增加自由硫酸应已产生从有机化合物的磺化过程中废水中厌氧消化。
代谢的磺化有机化合物（合成和染料）涉及的主要步骤组成的sulpholysis可能通过酶裂解的磺酸组从芳香核，可能是合理的解释为增加自由硫酸盐含量废水厌氧处理后。
该支队磺酸组从有机基质便利羟基化合物进行进一步纳入碳代谢导致减少生物无效。
厌氧处理的废水进一步处理CAACO反应堆。
的概念，加强了技术是：（1）固定的生物体中的承运人矩阵将允许高密度保持在一个生物反应器因此反应速率的增加；（2）减少平均自由程的生物催化剂，以提高基板利用酶的底物；（3）减少细胞合成使用生物（化合自营菌）与低产合作效率。
在介孔碳。
那个降解有机物的固定化细菌培养的活性炭的组合发生的物理吸附和生物降解（Ehrhardt ，1989年）。
固定化细菌能够在缺氧区片段到简单的有机物和化合物的细菌好氧区执行氧化有机物。
除了细菌氧化，催化氧化也是在积极的促进网格的碳矩阵。
活性炭保护生物体的毒性作用的有机物（Morsen，1990年）。
有机物的吸附脱附，弥漫出碳，之后可以被代谢。
解吸的速度取决于培养状况，流体动力学，代谢活性生物体和密度的颗粒（Fan，1990年）。
表3 质量平衡中的硫废水的厌氧消化出院皮革工业硫酸盐含量（单位：mg/l）物质含量初级澄清S2-在气态相厌氧反应堆S2-在水溶液中相厌氧反应堆总硫化物生成利用硫酸为中S2-生成的预计硫酸厌氧废水实际硫酸厌氧废水硫酸变化1113 6.4 188 195 585 528 965 437此外，燃烧热释放有机物的活跃的位置将用于激励的有机分子越过活化能屏障，通常决定利率的任何化学反应（约翰，2004年）。