环境工程外文文献及翻译水处理

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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%.。

水处理英文文献

Energy Dispersive X-ray Fluorescence Analysis of Mine Waters from the Migori Gold Mining Belt in Southern Nyanza,KenyaO.B.Odumo •A.O.Mustapha •J.P.Patel •H.K.AngeyoReceived:6January 2011/Accepted:2June 2011/Published online:17June 2011ÓSpringer Science+Business Media,LLC 2011Abstract Analyses of water samples from Mikei,Osiri,Masara and Macalder (Makalda)gold mines of the Migori gold mining belt of Southwestern Kenya were done to determine the level of heavy metals using the Energy Dis-persive X-ray Fluorescence technique.The concentrations of the heavy metals were;copper (29.34±5.01–14,975.59±616.14l g/L);zinc (33.69±4.29–683.15±32.93l g/L);arsenic (958.16±60.14–18,047.52±175.00l g/L)and lead (19.51±5.5–214.53±6.29l g/L).High levels of arsenic and lead were noted.These heavy metals are not only dangerous to the lives of miners and the local inhabitants;they are also a threat to aquatic life since these waters ﬁnally ﬁnd their way into Lake Victoria.Keywords ED-XRF ÁHeavy metals ÁGold mining ÁMine waterA number of studies conducted in gold mining areas e.g.,in the Witwatersrand have produced increasing evidence that mines frequently contaminate adjacent environment with heavy metals,salts and radionuclides,(Bowell et al.1995).Heavy metals are of particular interest for a number of reasons;ﬁrstly they show a tendency to accumulate in the sediments and the soils,have a long persistence time and are non biodegradable.Secondly,they are ubiquitous in sediments and soil arising from both natural and anthro-pogenic sources with pathways including inheritance from the parent rocks,application of water as well as local and long range atmospheric and ﬂuvial deposits of emissions from dust and mining (Deb et al.2008).While in com-mercial mining there are some measures of environmental control,in artisanal mining there are no control measures and the mining environment is littered with tailings,overburdens and open pits.Trace amounts of metals can be found in minerals constituting mineralized rocks.The size reduction process like crushing,during ore processing increases the surface area of the reaction of rock/mineral particles thereby accelerating oxidation and/or chemical weathering and hence the release of metals (Getaneh and Alemayehu 2006).Many of the metals are essential at low concentra-tions for plants,animals and human health but at higher concentration they can be toxic.In some cases the con-centration of metals in different environmental media can exceed the maximum tolerable concentration and can cause harm to life;a number of case histories have been docu-mented and reported from different parts of the world (Getaneh and Alemayehu 2006).Due to the presence of gold and copper,we expected many heavy metals to be associated with the artisanal gold mining activities in the Migori gold mining belt as reported elsewhere in the world (Getaneh and Alemayehu 2006;Ogola et al.2002;Serfor-Armah et al.2006;Veiga and Hinton 2002;Weast 1968).This study was therefore meant to assess accumulation of heavy metals in the mine waters in the Migori gold mining belt and make relevantO.B.Odumo (&)ÁJ.P.Patel ÁH.K.Angeyo Department of Physics,University of Nairobi,P.O.Box 30197-00100,Nairobi,Kenya e-mail:******************.ke J.P.Patele-mail:****************.ke H.K.Angeyoe-mail:*******************.keA.O.MustaphaDepartment of Physics,University of Agriculture Abeokuta,2240Abeokuta,Nigeriae-mail:******************.keBull Environ Contam Toxicol (2011)87:260–263DOI 10.1007/s00128-011-0332-xrecommendations to the miners,the local populace and government authorities .Materials and MethodsEleven water samples were collected from Osiri,Macalder (Makalda),Mikei and Masara gold mines for heavy metal analysis.Ten of the eleven water samples were collected from panning ponds dug in the ground near the crushing sites,one each from Masara,Osiri A and Macalder.Three and four water samples,respectively were collected from Osiri B and Mikei,the eleventh sample was collected from one of the freshly dug mines at Mikei.At each sampling point,the bottles were rinsed at least three times with the water before taking the sample by immersing the bottle to about 10cm below the water surface.The samples were tightly sealed and brought to the Nuclear Institute of Sci-ence and Technology,University of Nairobi for analysis.One hundred mL of each water sample was precon-centrated by adding Nitric acid,where the pH went below 3.5;ammonium solution was added to adjust it upwards.Two mL of 1%ammonium-1-pyrolidonedithiocabomate (APDC)solution was then added to the preconcentrate before stirring for about 30min,this was followed by suction ﬁltration over a 0.45l m nuclear pore ﬁlter paper (47mm in diameter)and left to dry.Although there are many X-ray ﬂuorescence techniques,the energy dispersive X-ray ﬂuorescence (ED-XRF)tech-nique was preferred for this analysis because it offers non destructive and reliable multi-elemental analysis capabil-ity.This technique also requires little sampling and sample preparation.The ED-XRF spectrometer used in this studyconsisted of a X-ray generator as the excitation source operated at 35V and 20mA;Canberra Si (Li)detector,an ORTEC spectroscopy shaping ampliﬁer model 571,OR-TEC high voltage supply bias model 475,ORTEC liquid nitrogen monitor and a Canberra multichannel analyzer (S-100)interfaced with a 486channel personal computer.Each ﬁlter was run for 500s and the spectra collected by the Canberra detector with energy resolution of 195eV for (Mn-K a )X-rays at 5.9keV.The characteristic X-ray spectra obtained from the samples was evaluated by non-linear least squares ﬁtting using the AXIL-QXA software.Figure 1shows a typical ED-XRF water spectrum obtained from the analysis.Result and DiscussionThe levels and detection limits of chromium,manganese,Iron,cobalt,copper,zinc,arsenic and lead are reported in Tables 1and 2,respectively,where copper,iron and magnesium were registered in all the samples collected.Concentration of cop-per ranged from 29.3±5.0–14,975.6±616.1l g/L.The average levels of copper at Mikei and Osiri B were 81.504and 31.377l g/L,respectively.Iron level ranged from 261.7±29.7–77,903.1±3,203.1l g/L.Zinc level at Osiri A was the lowest,33.7±4.3l g/L,while the highest level of 683.2±32.9l g/L was registered at Macalder panning pool.Average level of zinc of 183.2±13.2and 44.9±6.5l g/L were registered at Mikei and Osiri B,respectively.Absence of gold and mercury were noted in all the mine waters.For mercury,this could be due to its high density that makes it settle at the bottom of the pond with thesediments.Fig.1Typical ED-XRF spectrum of a water sampleArsenic was detected in Macalder and Mikei samples,the highest level of 18,047.5±175.0l g/L was registered at Mikei,and this conﬁrms the study by Odumo et al.(2011)that found the level of arsenic to be higher in sed-iments at Mikei.This level is high compared to results from Adola region of Ethiopia where its average was found to be 92.8l g/L (Deb et al.2008).However,the concen-tration is lower than 72mg/L registered at the Iron Duke mine in Zimbabwe (Williams and Smith 2000).Even though the miners don’t drink these waters directly,they use them to clean their hands before eating at the mines.Cows,goats and sheep also in many occasions especially during dry periods drink these waters.The situation is worsened when this contaminated water ﬁnd its way into the nearby rivers leading to direct domestic use by the locals since the rivers are their only source of water.The high level of arsenic can be dangerous to the miners and their livestock since it is toxic to both animals and human beings.However,the high level of arsenic should also be exploited if the concentration is economically viable since pure arsenic metal is used to produce crystalline gallium arsenide which is a semiconductor used in computing and electronic industries.It can also be used in agriculture,livestock and general industries (Winde and Sandham 2004).Lead was also registered at higher levels from Mikei,this poses a threat to the lives of the miners since lead is a carcinogen.Other heavy metals like cobalt,manganese and titanium detected in some of the mines at low concentrations.From this study,the concentration arsenic,copper,zinc and lead in the Migori gold mine waters is high and the miners should therefore be made aware of the conse-quences of their exposure to them.The miners should be educated on the possible ways of protecting themselves from the exposure to these heavy metals.Proper procedure of disposal of the mine wasters should be followed to avoid further contamination of the environment.It is also sug-gested that a further study be carried out to verify the results of this study using other methods.Though con-tamination of the rivers in the area had been done,theT a b l e 1E l e m e n t a l c o n c e n t r a t i o n i n w a t e r s a m p l e f r o m O s i r i ,M i k e i ,M a c a l d e r a n d M a s a r a (l g /L )M a s 1M a c 2M i k 1M i k 2M i k 3M i k 4M i k 5O s i -AO s i -B 1O s i -B 2O s i -B 3E l e m e n tT i\30112.9±5.146.5±11.3207.5±24.9\3084.3±11.7185.6±13.823.9±6.9\30\30\30C r144.9±25.2\2522.4±7.569.4±12.539.2±8.530.2±9.948.1±11.3\25\25\25\25M n339.8±5.735.0±8.5\15158.0±15.978.2±8.346.7±9.0132.6±15.134.5±7.3\15\1529.0±8.2F e77,903.1±203.11,174.8±66.91,153.7±97.411,710.9±492.13,101.0±148.01,834.6±89.211,775.3±494.0849.6±2.7520.±40.6261.6±29.7360.5±32.7C o1,014.1±72.7\10\1062.8±6.737.5±8.627.9±8.651.9±12.0\10\10\10\10C u14,975.6±616.145.3±6.793.0±9.5113.6±7.770.9±7.667.4±5.962.7±5.634.0±4.629.3±5.030.1±4.234.7±7.0Z n444.2±21.8683.2±32.9169.8±21.7291.3±16.1102.5±6.9113.8±7.7238.3±13.933.7±4.356.5±4.334.1±6.944.0±8.4A s\2058.2±15.6\20958.2±60.11,184.4±78.818,047.5±746.04,058.9±175.0\20\20\20\20P b 88.1±9.624.1±4.8\10200.9±13.1214.5±16.319.5±5.5\10\10\10\10\10M a s M a s a r a ,M a c M a c a l d e r ,M i k M i k e i ,O s i O s i r i Table 2Detection limits in water samples (l g/L)Element Detection limit Ti 30Cr 25Mn 15Fe12Co 10Cu 8Zn 7As20Pb10concentration of these metals should be investigated downstream.Acknowledgments We thank the Department of Physics,Univer-sity of Nairobi,for funding this research.ReferencesBowell RJ,Warre A,Minjera HA,Kimaro N(1995)Environmental impact of former gold mining on the Orangi river Serengeti N.P.,Tanzania.Biogeochemistry28:131–160Deb M,Tiwari G,Lahiri-Dutt K(2008)Artisanal and small scale mining in India:selected studies and overview of the issues.Int J Min Reclam Environ22(3):194–209Getaneh W,Alemayehu T(2006)Metal contamination of the environment of placer and primary gold mining in the Adola region of southern Ethiopia.Environ Geol50:339–352 Odumo OB,Mustapha AO,Patel JP,Angeyo HK(2011)Multiele-mental analysis of Migori(Southwest,Kenya)artisanalgoldmine ores and sediments by ED X-rayﬂuorescence technique:implications of occupational exposure and environ-mental impact.Bull Environ Contam Toxicol86(5):484–489 Ogola JS,Mutulah WV,Omullo MA(2002)Impact of gold mining in the environment and human heath:a case study in Migori Goldbelt,Kenya.Environ Geochem Health24:141–158 Serfor-Armah Y,Nyarkoh BJB,Adottey DK,Dampare SB,Adamako D(2006)Levels of arsenic and antimony in water and sediment from Prestea:a gold mining town in Ghana and its environs.Water Air Soil Poll175:181–192Veiga MM,Hinton J(2002)Abandoned artisanal gold mines in Brazilian Amazon:a legacy of mercury contamination.Nat Resour Forum26:15–26Weast RC(1968)Handbook of chemistry and physics.The Chemical Rubber Company,USAWilliams TM,Smith B(2000)Hydrochemical characterization of acute acid mine drainage at the iron duke mine,Mazowe, Zimbabwe.Environ Geol39(3–4):272–278Winde F,Sandham LA(2004)Uranium pollution of South African streams:an overview of the situation in gold mining areas of the Witwatersrand.Geol J61:131–149。

英文+译文+ 环境工程

Comparative evaluation of mass transfer of oxygenin three activated sludge processes operating under uniform conditionsVenkatram Mahendraker, Donald S. Mavinic, and Kenneth J. Hall Abstract: This investigation was conducted in three laboratory-scale activated sludge processes, namely, the conventional completely mixed activated sludge process (CMAS), the modified Ludzack-Ettinger process (MLE), and the University of Cape Town (UCT) process. These systems were operated under controlled conditions by feeding a uniform influent at a single 10-d solids retention time (SRT). The oxygen transfer parameters (K Laf, OTR f, and OTE f) determined indicated that the alpha (α) and oxygen transfer efficiency (OTE f) in processes where the enhanced biological phosphorus removal (EBPR) mechanism was active were higher than in the conventional completely mixed activated sludge (CMAS) process, where such a mechanism was absent. Thus, presenting a clear evidence of improved oxygen utilization in activated sludge processes contain aerobic, anoxic, and anaerobic selector zones.Key words: biological nutrient removal, completely mixed activated sludge process, oxygen uptake rate, oxygen transfer efficiencyMaterial and methodsFig. 1.Schemes for (a) completely mixed activated sludge (CMAS) process, (b) modified-Ludzack Ettinger (MLE) process and (c) University of Cape Town (UCT) process.The CMAS, MLE, and UCT process schemes employed in this study are shown in Fig.1. In these processes, the aerobic, anoxic, and anaerobic reactor volumes were 16 L, 8.55 L, and 3.85 L, respectively, whereas, the clarifier volume was equal to 5.25 L. The percentage of anoxic reactor volume was equal to 35％of the total process volume (excluding the clarifier ) in the MLE process, whereas, the percentages of anoxic and anaerobic volumes were equal to 30％and 13.5％(excluding the clarifier ), respectively, in the UCT process. The influent and biomass recirculation flow rates (including return activated sludge) were constant at 3L/h, in all systems. Each of the reactors had a mixer operating at 60 rpm for mixing the reactor contents, and the clarifier had an internal scraper rotating at 4 rpm to dislodge the attached biomass. The entire set-up was located within a temperature-controlled room set at 20±0.5℃and the systems were operated at a 10-d SRT. The aerobic reactor had a fine-pore ceramic diffuser ( Model Number AS2, Aquatic Ecosystems, Florida) made from heat-bonded-silica with a maximum pore size of 140 ?m, producing air bubbles of 1 mm to 3 mm radius in clean water. The air to the diffuser was supplied via an air pressure regulator, Pressure gauges, and a high precision flow meter (accuracy ±2％; flow range 90 to 2520 mL·min-1, LABCOR Catalogue #P-32044-18, Tube # 023-92ST) and controlled manually to maintain a DO concentration of 2 to 3 mg·L-1in the aerobic reactor.At least twice a week during “normal operational days”, and daily during “oxygen transfer test days”, grab samples from the feed tank, aerobic, anoxic, and anaerobic reactors, as well as the effluent were collected for analyses. The parameters analyzed included mixed liquor suspended solids(MLSS)(Standard Method 2540D), mixed liquor volatile suspended solids(MLVSS) (Standard Method 2540E),chemical oxygen demand(COD) (Standard Method 5220D),total organic carbon(TOC) (Standard Method 5310B), ammonia-nitrogen(NH3-N), nitrite plus nitrate nitrogen species (NO X-N),orthophosphate(PO4-P),total phosphorus(TP), total Kjeldahl nitrogen(TKN), conductivity and sludge volume index(SVI),generally following Standard Methods(APHA et al.1992). All inorganic analysis was done on a Lachat QuickChem Automated表一综合废水进水特性（以mg·L-1计）注：SD，标准；N，数据点的数量；TN，总氮。

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。

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。

环境工程外文文献及翻译-水处理

氧化沟工艺在污水处理中的应用和发展摘要:本文主要阐叙了Carrousｅl氧化沟的结构、工艺机理、运行过程中存在的问题和相应的解决办法.最后,介绍了Ｃaｒrouｓel氧化沟的最新的研究进展并指出了未来的主要研究方向。

关键词：Cａｒrｏｕseｌ氧化沟除磷脱氮结构机理1、前言氧化沟又名连续环曝气池,是活性污泥法的一种变形。

氧化沟处理工艺在２０世纪50年代由荷兰卫生工程研究所研制成功的.自从1９５4年在荷兰的首次投入使用以来。

由于其出水水质好、运行稳定、管理方便等技术特点,已经在国内外广泛的应用于生活污水和工业污水的治理。

目前应用较为广泛的氧化沟类型包括:帕斯维尔氧化沟、卡鲁塞尔氧化沟，奥尔博氧化沟、T型氧化沟、DE型氧化沟和一体化氧化沟。

这些氧化沟由于在结构和运行上存在差异,因此各具特点。

本文将主要介绍Carｒousel氧化沟的的结构、机理、存在的问题及其最新发展.2、Caｒrouｓｅｌ氧化沟的结构Cａｒrouseｌ氧化沟是19６7年由荷兰的DHV公司开发研制．在原Ｃarrouｓe氧化沟的基础上DＨV公司和其在美国的专利特许公司EＩＭCO又发明了Caｒrｏusｅｌ20０0系统,实现了更高要求的生物脱氮和除磷功能。

至今世界上已有85０多座Carrousｅl氧化沟和Carrousｅl 2０00系统正在运行。

Carrouｓel氧化沟使用定向控制的曝气和搅动装置,向混合液传递水平速度,从而使被搅动的混合液在氧化沟闭合渠道内循环流动。

因此氧化沟具有特殊的水力学流态,既有完全混合式反应器的特点,又有推流式反应器的特点，沟内存在明显的溶解氧浓度梯度。

氧化沟断面为矩形或梯形，平面形状多为椭圆形,沟内水深一般为2.5~４.5ｍ,宽深比为2：１,亦有水深达7m的,沟内水流平均流速为０．3m/s。

氧化沟的曝气混合设备有表面、曝气转刷或转盘,射流曝气池、导管式曝气器和提升管曝气机等,近年来配合使用的还有水下推动器。

3、Carｒoｕｓel氧化沟的机理3.1Ｃａｒｒousel氧化沟处理污水的机理最初的普通Carrousel氧化沟的工艺中污水直接与回流污泥一起进入氧化沟系统。

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。

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。

环境工程专业英语文献中英双语版

Treatment of geothermal waters for production ofindustrial, agricultural or drinking waterDarrell L. Gallup ∗Chevron Corporation, Energy Technology Company, 3901 Briarpark Dr., Houston, Texas 77042, USAReceived 14 March 2007; accepted 16 July 2007Available online 12 September 2007AbstractA conceptual study has been carried out to convert geothermal water and condensate into a valuable industrial, agricultural or drinking water resource. Laboratory and field pilot test studies were used for the conceptual designs and preliminary cost estimates, referred to treatment facilities handling 750 kg/s of geothermal water and 350 kg/s of steam condensate. The experiments demonstrated that industrial, agricultural and drinking water standards could probably be met by adopting certain operating conditions. Six different treatments were examined. Unit processes for geothermal water/condensate treatment include desilication of the waters to produce marketable minerals, removal of dissolved solids by reverse osmosis or evaporation, removal of arsenic by oxidation/precipitation, and removal of boron by various methods including ion exchange. The total project cost estimates, with an accuracy of approximately ±25%, ranged from US$ 10 to 78 million in capital cost, with an operation and maintenance (or product) cost ranging from US$ 0.15 to 2.73m−3 of treated water.© 2007 CNR. Published by Elsevier Ltd. All rights reserved. Keywords:Geothermal water treatment; Water resources; Desilication; Arsenic; Boron1. IntroductionWith the world entering an age of water shortages and arid farming land, it is increasingly important that we find ways of recycling wastewater. The oil, gas and geothermal industries, for example, extract massive amounts of brine and water from the subsurface, most of which are injected back into underground formations. Holistic approaches to water management are being adopted ever more frequently, and produced water is now being considered as a potential resource. In the oil and gas arena, attempts have been made to convert produced water for drinking supply or other reuses (Doran et al., 1998). Turning oilfield-produced water into a valuable resource entails an understanding of the environmental and economic implications, and of the techniques required to remove dissolved organic and inorganic components from the waters. Treatments of geothermal water and condensate for beneficial use, on the other hand, involve the removal of inorganic components only.We have explored the technical and economic feasibility of reusingwaters and steam condensates from existing and future geothermal power plants. Produced geothermal fluids, especially in arid climates, should be viewed as valuable resources for industry and agriculture, as well as for drinking water supplies. This paper presents the results of laboratory and field pilot studies designed to convert geothermal-produced fluids into beneficially usable water. The preliminary economics of several water treatment strategies are also provided.2. Design layoutThe layout for the treatment strategies (units of operation) have been designed specifically for a nominal 50Mwe geothermal power plant located in an arid climate of the western hemisphere, hereafter referred to as the test plant. The average concentration of constituents in the produced water is shown in Table 1. The amount of spent water from the test flashplant is ∼750 kg/s. The potential amount of steam condensate that could be produced at the plant is ∼350 kg/s. Table 1includes the compositionof the steam condensate derived from well tests. The six treatment cases considered in the study are given in Table 2, together with product flows and unit operations of treatment. Fig. 1 provides simplified schematic layouts of the unit operations for each case.3. Evaluation of treatment optionsIn this section the various operations considered for each case are described.3.1. Arsenic removalT he techniques considered viable for removing traces of arsenic (As) from condensate or from water are ozone oxidation followed by iron co-precipitation or catalyzed photo-oxidation processes (Khoe et al., 1997). Other processes for extracting As from geothermal waters (e.g. Rothbaum and Anderton, 1975; Umeno and Iwanaga, 1998; Pascua et al., 2007) have not been considered in the present study. In the case of the test plant, ozone (O3) would be generated on-site using parasitic power, air and corona-discharge ultra-violet (UV) lamps, and iron in the form of ferric sulfate [Fe2(SO4)3] or ferric chloride (FeCl3) that would be delivered to the geothermal plant. The photo-oxidation processes consist of treating the condensate or water with Fe2+ in the form of ferrous sulfate (FeSO4) or ferrous chloride (FeCl2), or with SO2 photo absorbers. The latter is generated from the oxidation of H2S in turbine vent gas (Kitz and Gallup,1997).The photo-oxidation process consists of sparging air through the photo- adsorber-treated fluid, and then irradiating it with UV lamps or exposing it to sunlight to oxidize As3+ to As5+. In the Fe photo-oxidation mode, the Fe2+ is oxidized to Fe3+, which not only catalyzes the oxidation reaction, but also co-precipitates the As. In the SO2 photo-oxidation mode,after oxidizing the As, FeCl3 or Fe2(SO4)3 is added to the water to precipitate the As5+ as a scorodite-like mineralTable 1Approximate geothermal water and steam condensate compositions assumed in the studya Total dissolved solids.Table 2Summary of the six cases of geothermal fluid treatment to produce marketable watera On treatment of water, clays are produced at a rate of 7.4 ton/h.(FeAsO4·2H2O). In the laboratory and field pilot tests, the photo-absorber and UV dosages were varied to decrease the As concentration in geothermal fluids to below the detection limit of 2 ppb (Simmons et al., 2002). Residual As in the precipitate may be slurry-injected into a water disposal well or fixed/stabilized for land disposal to meet United States Environmental Protection Agency (USEPA) Toxicity Characterization Leach Procedure (TCLP) limits using special cement formulations (Allen, 1996).3.2. Ion exchangeStrong-base anion exchange resins have been shown to remove traces of As in geothermal fluids provided that the amorphous silica is decreased below its saturation point or the water stabilized against silica scaling by acidification. The ion exchange alternative to As removal by oxidation/precipitation has proven successful in reducing the concentrations of this element to below the limits set for drinking water standards. As part of the present study, laboratory and field columnar tests were successfully conducted with geothermal hot spring water containing 30 ppm As. Pre-oxidation of As3+ is required to achieveacceptable As removal by ion exchange. In these columnar tests, NaOCl and H2O2 were used to pre-treat the hot spring water to oxidize As3+ to As5+. Chloride-rich water, which had been treated with lime (CaOH2) and filtered to reduce amorphous silica to well below its saturation point, successfully regenerated the resin. In the field, and for simplicity of operation, we concluded that ozone/Fe co-precipitation or catalyzed photo-oxidation would be preferred for water treatment over ion exchange as this would eliminate the need to purchase and transport additional chemicals. On the other hand, ion exchange is an attractive option for extracting As from condensate.Special ion-exchange resins have proven successful in removing boron (B) from geothermal fluids (Recepoglu and Beker, 1991; Gallup, 1995). Hot spring water from the geothermal field, containing 25 ppm B, had its B content decreased to <1 ppm in a laboratory columnar test. The resin was regenerated with sulfuric acid (H2SO4). No deterioration in resin performance was observed up to 10 loading and regenerationcycles.Fig. 1. Flow chart of the basic unit operations involved in treatment cases 1–6.3.3. pH adjustmentThe majority of the cases considered in this study require adjustment to pH. Adding soda ash (Na2CO3) can increase the buffering capacity of the water and condensate. Soda ash or lime treatment can also be used to enhance precipitation of certain species. Purchased H2SO4, on-site generated sulfurous acid (H2SO3) or on-site generated hydrochloric acid (HCl) can be used to acidify waters to meet reuse requirements or to inhibit silica scaling (Hirowatari, 1996; Kitz and Gallup, 1997; Gallup, 2002). A number of geothermal power plants around the world utilize water acidification to inhibit silica scaling. Unocal Corporation commenced this practice of pH adjustment of hot and cold geothermal fluids in commercial operations in the early 1980s (Jost and Gallup, 1985; Gallup et al., 1993; Gallup, 1996). In water acidification the pH is reduced slightly so as to slow down the silica polymerization reaction kinetics without significantly increasing corrosion rates.3.4. Cooling pondsIn this water processing option, the water is cooled in open, lined ponds prior to injection or treatment for beneficial use. The flashed water is allowed to flow into the pond where it “ages” for up to 3 days; this is a sufficient length of time to achieve amorphous silica saturation at ambient temperature, which is assumed to be below 20 ◦C most of the year. Adjustment of the water pH to 8.0±0.5 with soda ash or lime enhances water desilication, resulting in undersaturation with respect to amorphous silica (Gallup et al., 2003). At 15 ◦C, the solubility of amorphous silica in the water in our test field is predicted to be about 90 ppm (Fournier and Marshall, 1983). In a large bottle, field water wasadjusted from pH 7.2 to 8.1 with soda ash and allowed to cool to 15 ◦C over a period of 90 min. The resultant dissolved silica [Si(OH)4] concentration in the supernatant fluid was 54 ppm (undersaturated by about 40%).3.5. FiltrationSand and plate/frame filters were adopted in this study to polish water and dewater sludges, respectively. This does not mean that other filters could not be used in the water treatment project. At the Salton Sea (California, USA) geothermal field, for example, flocculated secondary clarifiers and pressure or vacuum filters have been adopted with success for many years as alternatives to media and plate/frame filters, respectively (Featherstone et al., 1989).3.6. Multi-stage vacuum-assisted evaporatorIn this unit of operation, cool, ponded water is combined with cooled and re-circulated water (from the evaporator heat rejection stages), and pumped to the heat recovery portion of the evaporator system. The cool water provides the thermal sink for the vapors from the final stages of the evaporator concentrate. The inlet water and concentrate flow countercurrent in the evaporator. After flowing through the heat recovery stages, the water temperature has increased somewhat. Most of this heated water is sent to a separate cooling pond before returning to the heat recovery stages. A portion of the heated water continues on through the heat recovery stages; the water also functions as the heat sink for this portion of the process.After the heat recovery stages, the water is heated with steam and returned to the heat recovery stages for flashing. The water proceeds through the heat recovery and rejection stages until it is fully concentrated. The concentrate is sent to an injection well, while the distillate is collected and re-routed for pH adjustment, as required, before passing to other treatments discussed here. The evaporator has not yet been tested at the field; the present discussion is provided for conceptualization only.3.7. Reverse osmosisThe reverse osmosis (RO) process removes dissolved salts through fine filtration at the molecular level of water. The RO membrane allows water to pass through but blocks 98% of the salts. The typical RO operating pressure is 2760–3100 kPa, which is achieved by gravity flow from the power plant to the RO unit located 300m downhill. The RO feed is pre-treated with a 2 _m cartridge filter. The rejected fluid is injected into a disposal well, while the permeate can be sent to other treatment units for polishing.The RO unit has not yet been tested at the field; the present discussion is again provided for conceptualization only. However, RO has been successfully tested at the Mammoth Lakes, California, USA, field to recover useable silica (Bourcier et al., 2006).3.8. Desilication and production of claysSilica can be eliminated from the water by holding the latter in cooling ponds for up to 3 days. Soda ash or lime can be added to the water to enhance silica precipitation. Laboratory and field jar test experiments showed that desilication of the water can also be achieved by treating with various metal cations at elevated pH to precipitate metal silicates. Below ∼90 ◦Cand at elevated pH (typically 9–10) treatments with caustic soda (NaOH), magnesium hydroxide [Mg(OH)2], lime, strontium hydroxide [Sr(OH)2], barium hydroxide [Ba(OH)2], ferric hydroxide [Fe(OH)3], birnessite [(Na,Ca)0.5(Mn4+,Mn3+)2O4· 1.5H2O], copper hydroxide, [Cu(OH)2] and zinc hydroxide [Zn(OH)2] precipitated only amorphous or poorly crystalline metal-rich silicates of little commercial value. Treatment of water with alkaline-earth metals below ∼90 ◦C, except magnesium, tended to co-precipitate metal carbonates. Laboratory reactions conducted at ∼130 ◦C demonstrated that certain metal ions may react with the silica in the water to precipitate crystalline compounds of commercial value. For example, kerolite1 clay was precipitated upon treating synthetic and field waters with magnesium at 130 ◦C, whereas, under similar conditions, sodalite (Na4Al3 Si3O12Cl) and Zeolite P2 were precipitated upon treatment with aluminum hydroxide or sodium aluminate (Gallup et al., 2003; Gallup and Glanzman, 2004). Treatment of waters with a combination of magnesium and iron precipitated hectorite (i.e. a lithium-rich clay mineral of the montmorillonite group).The desilication process designed for the field consists of a crystallizer-clarifier similar to those used at the Salton Sea field (Newell et al., 1989). For kerolite production, magnesium chloride (MgCl2) is added at slightly above stoichiometric proportions (3Mg:4Si) and the pH is increased to ∼10.0 with caustic soda or lime. The crystallizer and clarifier include sludge recirculation to maximize the “seed crystal” effect, thus providing a high surface area for precipitation. After precipitation, the water is clarified, possibly treated further to meet industrial water specifications, cooled to pipeline specifications, and finally sent to a pipeline for transport to the industrial site. The kerolite sludge is dewatered using a filter, as discussed earlier. The dewatered sludge can be dried in a steam-heated kiln or in an arid, but cool environment at the power plant. Dried kerolite is transported off-site for commercial refining and use. In zeolite manufacture, sodium aluminate (NaAlO2) is used both as the Al and base source. Hectorite or saponite (i.e. a magnesium-rich clay mineral of the montmorillonite group) are made1 Kerolite is a disordered form of talc.2 Zeolite P refers to various forms of gismodine.Table 3Quality of the water end-product estimated from actual testing and from vendor treatment specifications for the six treatment cases described in Table 2a TDS: total dissolved solids.in a similar fashion by treating water with Mg2+ and Fe2+ salts and a base (Gallup et al., 2003). Adding a little brucite [Mg(OH)2] or MgCl2 will also produce a nearly pure silica by-product for industrial uses (Lin et al., 2001). Desilication of water with precipitation of valuable minerals is a preferred option as opposed to simply allowing the silica to deposit in cooling ponds as it adds value to the geothermal power project by simultaneously controlling scale deposition and producing marketable products. Once the water is treated for desilication, any metals of commercial value can be extracted by means of well-documented processes (Maimoni, 1982; Featherstone, 1988; Duyvesteyn, 1992; Featherstone and Furmanski, 2004). This approach is particularly important if ion exchange or solvent extraction techniques have been used to concentrate and recover lithium, base and precious metals.4. Quality of the water end-productTable 3 gives details on the estimated quality of the water produced after each of the six treatment cases (see Table 2 for initial concentrations). The water qualities meet or exceed perceived drinking, agriculture and industrial standards at the location of the test plant.5. Preliminary cost estimatesTable 4 is a summary of the estimated capital and operating (product water) costs, based on construction of the geothermal power plant for the six treatment processes. Local market prices for chemicals such as H2SO4, CaO, flocculents, NaCl, Na2CO3, FeSO4, MgCl2, NaAlO2, etc., were used in the calculations. The product cost does not include a productstorage reservoir at the end of the pipeline where the treated water can be made available for industrial, agricultural or drinking uses. The anticipated selling price for finished minerals, such as kerolite, saponite, sepiolite (a magnesium-rich clay mineral), etc. was set at US$ 0.45 kg −1. For comparison, the cost of injecting all of the waste geothermal fluids back into the field (using wells with gravity feed) is ∼US$ 10,000,000. The latter is the estimated capital cost of drilling sufficient injection wells for water disposal, but does not include poten- Table 4Preliminary cost estimates (US$) for the six treatment cases described in Table 2a Water treatment cost offset by 7.5 ton/h of clay sales.tially high maintenance costs for acidification treatment and/or for re-drilling these injection wells.6. ConclusionsA preliminary study has been made of combining water treatment/reuse and electricity generation in a geothermal power plant located in an arid region of the western hemisphere. It has been assumed that good-quality water is scarce in the area and that there is a local demand for potable, agricultural and industrial water resources. Geothermal water and steam condensate require treatment prior to reuse. A variety of treatment scenarios have been considered to achieve water quality ranging from potable to industrial standards. Some proof-of-concept testing in the laboratory and the field has been conducted to ensure that certain qualities can be attained. Preliminary cost estimates have been made for the treatment schemes considered in the study. Promising processes have been developed to produce marketable water and silicate minerals. Desilication and removal of arsenic and boron from the water have also proved useful with a view to subsequent extraction of lithium, base and precious metals.AcknowledgmentsThe authorwould like to thank Chevron Corporation management for permission to publish this paper. CH2MHILL, Irvine, CA, provided many of the process ideas and cost estimates included here. The author appreciates the many useful comments and suggestions provided by the editors and by Mr. Paul Hirtz in his review of the manuscript.ReferencesAllen, W.C., 1996. Superplasticizer-cement composition for waste disposal. US Patent 5,551,976.Bourcier, W., Ralph, W., Johnson, M., Bruton, C., Gutierrez, P., 2006. Silica extraction at Mammoth Lakes, California.Lawrence Berkeley National Laboratory Report UCRL-PROC-224426. Livermore,CA, USA, 6 pp.Doran, G.F.,Williams, K.L., Drago, J.A., Huang, S.S., Leong, L.Y.C., 1998. Pilot study results to convert oil field producedwater to drinking water or reuse. Paper presented at 1998 SPE Annual Technical Conference and Exhibition, 27–30September. New Orleans, LA, USA, SPE Paper 49124, 15 pp.Duyvesteyn, W.P.C., 1992. Recovery of base metals from geothermal waters. Geothermics 21, 773–799.Featherstone, J.L., 1988. Process for removing silica from silica-rich geothermal water. US Patent 4,765,913.Featherstone, J.L., Furmanski, G., 2004. Process for producing electrolytic manganese dioxide from geothermal brine.US Patent 6,682,644.Featherstone, J.L., Spang, T., Newell, D.G., Gallup, D.L., 1989. Process and apparatus for reducing the concentration ofsuspended solids in clarified geothermal water. US Patent 4,874,529. Fournier, R.O., Marshall, W.L., 1983. Calculation of amorphous silica solubilities at 25◦ to 300 ◦C and apparent cationhydration numbers in aqueous salt solutions using the concept of effective density of water. Geochim. Cosmochim.Acta 47, 587–596.Gallup, D.L., 1995. Agricultural uses of excess steam condensate—Salton Sea geothermal field. Geotherm. Sci. Technol.4, 175–187.Gallup, D.L., 1996. Water pH modification scale control technology. Geotherm. Resour. Counc. Trans. 20, 749–755.Gallup, D.L., 2002. Method for simultaneously abating H2S and producing acid for water treatment. US Patent 6,375,907.Gallup, D.L., Barnes, M.L., Cope, D., Kolimlim, Q.S., Leong, J.K., 1993. Water heat exchanger treatment method. USPatent 5,190,664.Gallup, D., Sugiaman, F., Capuno, V., Manceau, A., 2003. Laboratory investigation of silica removal from geothermalwaters to control silica scaling and produce usable silicates. Appl. Geochem. 18, 1597–1612.Gallup, D.L., Glanzman, R.K., 2004. Method for synthesizing crystalline magnesium silicates from geothermal water.US Patent 6,761,865.Hirowatari, K., 1996. Scale prevention method bywater acidification with biochemical reactors. Geothermics 25, 259–270.Jost, J.W., Gallup, D.L. 1985. Inhibiting scale precipitation from high temperature water. US Patent 4,500,434.Khoe, G.H., Emett, M.T., Robins, R.G., 1997. Photoassisted oxidation of species in solution. US Patent No. 5,688,378.Kitz, K.R., Gallup, D.L., 1997. pH modification of geothermal water with sulfur-containing acid. US Patent 5,656,172.Lin, M.S., Premuzic, E.T., Zhou,W.M., Johnson, S.D., 2001. Mineral recovery: a promising geothermal power productionco-product. Geotherm. Resour. Counc. Trans. 25, 497–500.Maimoni, A., 1982. Mineral recovery from Salton Sea geothermal waters: a literature review and proposed cementationprocess. Geothermics 11, 239–258.Newell, D.G., Whitescarver, O.D., Messer, P.H., 1989. Salton Sea Unit 3;47.5MWe geothermal power plant. Geotherm.Resour. Counc. Bull. 18 (5), 3–5.Pascua, C.S., Minato, M., Yokoyama, S., Sato, T., 2007. Uptake of dissolved arsenic during the retrieval of silica fromspent geothermal brine. Geothermics 36, 230–242.Recepoglu, O., Beker, U., 1991. A preliminary study of boron removal from Kizildere/Turkey geothermal waste water.Geothermics 20, 83–89.Rothbaum, H.P., Anderton, B.H., 1975. Removal of silica and arsenic from geothermal discharge waters by precipitationof useful calcium silicates. Geothermics 2, 1417–1425.Simmons, M., Gallup, D., Harden, D., 2002. Photo-oxidation, removal and stabilization of arsenic residuals in drinkingwater, wastewater and process water systems. Trends Geochem. 2, 73–84. Umeno, J., Iwanaga, T., 1998. A study on the abatement technology of the harmful chemical components in geothermalhot water. In: Proceedings of the 20th New Zealand Geothermal Workshop, pp. 209–213.处理地热废水来生产工业用水、农业用水或生活饮用水达雷尔L.盖洛普能源技术公司，雪佛龙公司Briarpark博士，美国德克萨斯州休斯顿摘要：一个概念的研究已经进行了转换成有价值的工业、农业和饮用水资源地热水和凝析油。

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。

(整理)环境工程专业英语翻译(中英对照)

Unit one Environmental Engineering环境工程What is this book about？这本书是关于什么的？The objective of this book is to introduce engineering and science students to the interdisciplinary study of environment problems；their cause，why they are of concern，and how we can control them. The book includes:这本书的目的是使理工科的学生了解跨学科间的研究环境问题;它们的起因，为什么它们受到关注，以及我们怎样控制它们。

这本书包括：●Description of what is meant by environment and environmental systems描述环境和环境系统意味着什么●Information on the basic causes of environmental disturbances关于引起环境干扰基础原因的基本信息●Basic scientific knowledge necessary to understand the nature of environmental problems and to be able toquantify them理解环境问题本质，并能够定量计算它们所必要的基本科学知识●Current state of the technology of environmental control in its application to water，air and pollution problems目前适用于水，空气和环境污染问题的环境控制技术的现状●Considerable gaps in our current scientific knowledge of understanding and controlling many of the complexinteractions between human activities and nature我们目前的科学知识在理解和控制人类活动和自然之间复杂的相互作用的科学知识上存在相当大的缺陷●Many environmental problems which could be eliminated or reduced by the application of current technology，butwhich are not dealt with because of society’s lack of will to do so，or in many instance because of a lack of resources to do so.许多环境问题可以应用现有技术消除或减少，但没有得到处理是因为社会缺乏这样做的意愿，或者像许多例子那样因为缺乏资源。

aao污水处理工艺外文文献译文

aao污水处理工艺外文文献译文Recent Upgrades to Aerobic Activated Sludge Treatment for Sewage (AAO)最近污水激活液体处理技术(AAO)的升级近年来，汉语激活液体处理技术(AAO)被广泛地应用于各种废水污水处理系统，特别是在有机物的分解过程中发挥了重要作用。

这种处理技术根据有机化合物的溶解及二氧化碳的气态收集，能够有效地帮助减少污染物的总量和质量。

而近些年来随着现代技术的发展，AAO处理技术也开始得到改良和更新。

Firstly, the science and technology surrounding AAO has been subject to a numberof improvements. For instance, there have been updates to the wastewater treatment process which have resulted in a more efficient removal of nitrogen and phosphorus with fewer risks of sludge build-up. This means that AAO systems can now be applied to a wider range of wastewater applications. In addition, new measuring systems have been developed to monitor the performance of AAO systems more precisely. This has opened up the possibility of making adjustments to the optimal parameters, which can help to ensure that the outcome of the process is as effective as possible.RR先后，AAO 技术围绕的科学技术也被进行了一系列的改进。

环境工程英语文献摘要范文

环境工程英语文献摘要范文English:"In recent years, there has been growing concern about environmental pollution caused by industrial activities. This has led to an increased focus on environmental engineering solutions aimed at mitigating pollution and promoting sustainability. One notable approach involves the development and implementation of advanced treatment technologies for wastewater treatment plants. These technologies aim to improve the efficiency of pollutant removal processes while minimizing energy consumption and environmental impact. Additionally, there is a rising interest in the utilization of renewable energy sources to power wastewater treatment processes, further aligning with sustainable practices. Furthermore, the integration of artificial intelligence (AI) and data analytics in environmental engineering has shown promising results in optimizing treatment processes, predicting pollution levels, and enhancing overall system performance. Moreover, the concept of circular economy has gained traction in the field of environmental engineering, emphasizing the importance of resource recovery and waste minimization. Through the implementation of circulareconomy principles, waste streams can be transformed into valuable resources, reducing the reliance on virgin materials and minimizing environmental degradation. Overall, these advancements in environmental engineering underscore the ongoing efforts to address environmental challenges and foster a more sustainable future."中文翻译："近年来，人们对工业活动引发的环境污染日益关注，这导致了对环境工程解决方案的增加关注，旨在减轻污染并促进可持续发展。

环境工程外文翻译外文原文

12Oxidation DitchNazih K.Shammas and Lawrence K.WangC ONTENTSI NTRODUCTIONP ROCESS D ESCRIPTIONA PPLICABILITYA DVANTAGES AND D ISADVANTAGESD ESIGN C RITERIAP ERFORMANCEP ACKAGE O XIDATION D ITCH P LANTSO PERATION AND M AINTENANCED ESIGN C ONSIDERATIONSC OSTSD ESIGNE XAMPLEN OMENCLATURER EFERENCESA PPENDIXAbstract An oxidation ditch is a modiﬁed activated sludge biological treatment process that uses long solids retention times(SRTs)to remove biodegradable organics.The typical oxidation ditch is equipped with aeration rotors or brushes that provide aeration and circula-tion.The wastewater moves through the ditch at1to2ft/s.The ditch may be designed for continuous or intermittent operation.Because of this feature,this process may be adaptable to theﬂuctuations inﬂows and loadings associated with recreation area wastewater production. Several manufacturers have developed modiﬁcations to the oxidation ditch design to remove nutrients in conditions cycled or phased between the anoxic and aerobic states.This chapter covers all aspects of the process including process description,applicability, design criteria,performance,package oxidation ditch plants,operation and maintenance, design parameters and procedure,costs and a worked out design example.From:Handbook of Environmental Engineering,Volume8:Biological Treatment ProcessesEdited by:L.K.Wang et al.c The Humana Press,Totowa,NJ513514N.K.Shammas and L.K.Wang Key Words Oxidation ditch r wastewater treatment r rotors r BOD r nutrients removal r design procedure r costs.1.INTRODUCTIONThe oxidation ditch,developed in the Netherlands,is a variation of the extended aeration process that has been used in small towns,isolated communities,and institutions in Europe and the United States.The typical oxidation ditch(Figure12.1)is equipped with aeration rotors or brushes that provide aeration and circulation.The wastewater moves through the ditch at1to2ft/s.The ditch may be designed for continuous or intermittent operation. Because of this feature,this process may be adaptable to theﬂuctuations inﬂows and loadings associated with recreation area wastewater production(1).2.PROCESS DESCRIPTIONAn oxidation ditch is a modiﬁed activated sludge biological treatment process that uses long solids retention times(SRTs)to remove biodegradable organics.Oxidation ditches are typically complete mix systems,but they can be modiﬁed to approach plugﬂow conditions. Typical oxidation ditch treatment systems consist of a single or multichannel conﬁguration within a ring or oval basin.As a result,oxidation ditches are called“racetrack type”reactors (2).Horizontally or vertically mounted aerators provide circulation,oxygen transfer,and aeration in the ditch.The cross-sectional area of the ditch is commonly4ft to6ft deep,with 45◦sloping sidewalls.Oxidation ditch systems with depths of10ft or more with vertical sidewalls and vertical shaft aerators may also be used.Ditches may be constructed of various materials,including concrete,gunite,asphalt,or impervious membranes.Concrete is the most common.L-and horseshoe-shaped conﬁgurations have been constructed to maximize land usage(3).Preliminary treatment,such as bar screens and grit removal,normally precedes the oxida-tion ditch.Primary settling before an oxidation ditch is sometimes practiced,but is not typicalefﬂuentin this design.Tertiaryﬁlters may be required after clariﬁcation,depending on theSettlingTankFig.12.1.Typical oxidation ditchﬂow diagram(1).Ditch 515requirements.Disinfection isrequired and reaeration may be necessary before ﬁnal discharge.Flow to the oxidation ditch is aerated and mixed with return sludge from a secondary clariﬁer.A typical process ﬂow diagram for an activated sludge plant using an oxidation ditch is shown in Figure 12.1.Surface aerators,such as brush rotors,disc aerators,draft tube aerators,or ﬁne bubble diffusers are used to circulate the mixed liquor.The mixing process entrains oxygen into the mixed liquor to foster microbial growth and the motive velocity ensures contact of microorganisms with the incoming wastewater.The aeration sharply increases the dissolved oxygen (DO)concentration but decreases as biomass uptake oxygen as the mixed liquor travels through the ditch.Solids are maintained in suspension as the mixed liquor circulates around the ditch.If design SRTs are selected for nitriﬁcation,a high degree of nitriﬁcation will occur.Oxidation ditch efﬂuent is usually settled in a separate secondary clariﬁer.An anaerobic tank may be added before the ditch to enhance biological phosphorus removal.An oxidation ditch may also be operated to achieve denitriﬁcation.One of the common design modiﬁcations for enhanced nitrogen removal is known as the Modiﬁed Ludzack-Ettinger (MLE)process (2,4–8).In this process,illustrated in Figure 12.2,an anoxic tank is added upstream of the ditch along with mixed liquor recirculation from the aerobic zone to the tank to achieve higher levels of denitriﬁcation.In the aerobic basin,autotrophic bacteria (nitriﬁers)convert ammonia-nitrogen to nitrite-nitrogen and then to nitrate-nitrogen.In the anoxic zone,heterotrophic bacteria convert nitrate-nitrogen to nitrogen gas which is released to the atmosphere.Some mixed liquor from the aerobic basin is recirculated to the anoxic zone to provide the mixed liquor with a high-concentration of nitrate-nitrogen to the anoxic zone.Several manufacturers have developed modiﬁcations to the oxidation ditch design to remove nutrients in conditions cycled or phased between the anoxic and aerobic states.Although the mechanics of operation differ by manufacturer,in general,the process consists of two separate aeration basins,the ﬁrst anoxic and the second aerobic.Wastewater and return activated sludge (RAS)are introduced into the ﬁrst reactor which operates under anoxic conditions.Mixed liquor then ﬂows into the second reactor operating under aerobicSludge Mixed Liquor RecirculationFig.12.2.The modiﬁed Ludzack-Ettinger process (2).516N.K.Shammas and L.K.Wang conditions.The process is then reversed and the second reactor begins to operate under anoxic conditions(2).Another proposed conﬁguration(9)is to obtain nitriﬁcation in the region just downstream of the brush aerators which is aerobic.As the liquor travels downstream and the oxygen is consumed,an anaerobic zone is formed.By routing a small portion of the raw sewage inﬂuent (as a carbon source)to this zone,denitriﬁcation occurs.The mixed liquor then contacts another brush aerator so that the organic nitrogen produced by the denitrifying bacteria is oxidized. The number of anaerobic zones and aerators required is a design parameter that depends on the capacity and loading of the plant.3.APPLICABILITYThe oxidation ditch process is a fully demonstrated secondary wastewater treatment technology,applicable in any situation where activated sludge treatment(conventional or extended aeration)is appropriate(10).Oxidation ditches are applicable in plants that require nitriﬁcation because the basins can be sized using an appropriate SRT to achieve nitri-ﬁcation at the mixed liquor minimum temperature(11).This technology is very effec-tive in small installations(wastewaterﬂows between0.1and10MGD),small communi-ties,and isolated institutions,because it requires more land than conventional treatment plants(2,3).The oxidation process as mentioned previously,originated in the Netherlands,with the ﬁrst full scale plant installed in V oorschoten,Holland,in1954.By the end of the century more than9200municipal oxidation ditch installations were operational in the United States (12).Nitriﬁcation to less than1mg/L ammonia-nitrogen consistently occurs when ditches are designed and operated for nitrogen removal.Today,a complete biological treatment system can be provided with a single oxidation ditch system.The oxidation ditch structure can be constructed with only a single aerator and an intrachannel clariﬁer.By incorporating denitriﬁcation within a channel of the oxidation ditch,alternating oxic/anoxic conditions can be created which will effectively reduce nitrogen concentrations to the desired low levels to meet the efﬂuent discharge regulations(13).Double or triple concentric ditch arrangement allows for variation in dissolved oxygen levels resulting in conditions that are favorable for the biomass to remove nitrogen and phosphorus(14).4.ADV ANTAGES AND DISADV ANTAGESThe main advantage of the oxidation ditch is the ability to achieve removal performance objectives with low operational requirements and operation and maintenance costs.Some speciﬁc advantages of oxidation ditches include(2):(a)An added measure of reliability and performance over other biological processes owing to aconstant water level and continuous discharge which lowers the weir overﬂow rate and eliminates the periodic efﬂuent surge common to other biological processes,such as SBRs.(b)Long hydraulic retention time and complete mixing minimize the impact of a shock load orhydraulic surge.Oxidation Ditch517 (c)Produces less sludge than other biological treatment processes owing to extended biologicalactivity during the activated sludge process.(d)Energy efﬁcient operations result in reduced energy costs compared with other biologicaltreatment processes.The disadvantages include:(a)Efﬂuent suspended solids concentrations are relatively high compared to other modiﬁcations ofthe activated sludge process.(b)Requires a larger land area than other activated sludge treatment options.This can prove costly,limiting the feasibility of oxidation ditches in urban,suburban,or other areas where land acquisition costs are relatively high.5.DESIGN CRITERIAOxidation ditches are commonly constructed using reinforced concrete,although gunite, asphalt,butyl rubber,and clay have also been used.Impervious materials are usually used to prevent erosion.The ditches are usually4to6ft deep with45degrees or vertical sidewalls(3).Screened wastewater enters the ditch,is aerated,and circulates at about0.25to0.35m/s (0.8to1.2ft/s)to maintain the solids in suspension(15).The RAS recycle ratio is from75 to150%,and the mixed liquor suspended solids(MLSS)concentration ranges from1500 to5000mg/L(15).The oxygen transfer efﬁciency of oxidation ditches ranges from2.5to 3.5lb/hp-h(2,16).The design criteria are affected by the inﬂuent wastewater parameters and the required efﬂuent characteristics,including the decision or requirement to achieve nitriﬁcation,deni-triﬁcation,and/or biological phosphorus removal.Speciﬁc design parameters for oxidation ditches include(2).5.1.Solids Retention Time(SRT)Oxidation ditch volume is sized based on the required SRT to meet efﬂuent quality require-ments.The SRT is selected as a function of nitriﬁcation requirements and the minimum mixed liquor temperature.Design SRT values vary from4to48or more days(2,3).Typical SRTs required for nitriﬁcation range from12to24days.5.2.BOD LoadingBOD loading rates vary from less than160mg/L/d(10lb/1000ft3/d)to more than 800mg/L/d(50lb/1000ft3/d)(2,3).A BOD loading rate of240mg/L/d(15lb/1000ft3/d) is commonly used as a design loading rate.However,the BOD loading rate is not typically used to determine whether or not nitriﬁcation occurs.5.3.Hydraulic Retention TimeAlthough rarely used as a basis for oxidation ditch design,hydraulic retention times(HRTs) within the oxidation ditch range from6to30hours for most municipal wastewater treatment plants(2,3).518N.K.Shammas and L.K.Wang6.PERFORMANCEAs fully demonstrated secondary treatment processes,oxidation ditch processes are readily adaptable for nitriﬁcation and denitriﬁcation.As part of an evaluation of oxidation ditches for nutrient removal(17),performance data were collected from17oxidation ditch plants. The average designﬂow for these plants varied between378and45,425m3/d(0.1to12 MGD).The average performance of these plants indicates that oxidation ditches achieveBOD,suspended solids,and ammonia nitrogen removal of greater than90%.Likewise, US EPA reported nitrogen removals of greater than90%from several oxidation ditch processes(2).It should be kept in mind that to be able to achieve such high nitrogen removals,it is imperative to have continuous plant supervision and skilled operation.This is essential for assuring full control of the dissolved oxygen(DO)proﬁle in the oxidation ditch system. Several modeling techniques have been proposed to help for DO control and to perform real time predictions of performance(18,19).The following sections discuss the performance of two recently designed oxidation ditch facilities.6.1.Casa Grande Water Reclamation FacilityThe City of Casa Grande,Arizona,Water Reclamation Facility began operation in February 1996.The system was designed to treat a wastewaterﬂow of15,142m3/d(4.0MGD)and uses an anoxic zone preceding the aerobic zone of each train to provide denitriﬁcation.With inﬂuent design parameters of270mg/L BOD,300mg/L TSS,and45mg/L TKN,the plant has consistently achieved efﬂuent objectives of10mg/L BOD,15mg/L TSS,1.0mg/L ammonia, and5.0mg/L nitrate-nitrogen.Table12.1summarizes the plant’s performance between July 1997and July1999(20).6.2.Edgartown,Massachusetts WWTPThe Edgartown,Massachusetts WWTP,located on the island of Martha’s Vineyard,is designed to treat757m3/d(0.20MGD)in the winter months and2,839m3/d(0.75MGD) in the summer.Two oxidation basins are installed and the plant has achieved performance objectives since opening.Table12.2summarizes average monthly inﬂuent,efﬂuent and percent removal data(21).Table12.1Performance of Casa Grande,AZ WWTP aParameter BOD TSS Total NInﬂuent,average monthly value,mg/L22620735Efﬂuent,average monthly value,mg/L952Removal,%969794a Data adapted from ref.20.Oxidation Ditch519Table 12.2Performance of Edgartown,MA WWTP aParameterBOD TSS Total N Inﬂuent,average monthly value,mg/L23820227Efﬂuent,average monthly value,mg/L352Removal,%999792a Data adapted from ref.21.7.PACKAGE OXIDATION DITCH PLANTSPackage plants are premanufactured treatment facilities used to treat wastewater in small communities.Package plants are usually designed by manufacturers to treat ﬂows as low as 0.002MGD to as high as 0.5MGD (22,23).7.1.DescriptionPackage oxidation ditches are typically manufactured in sizes that treat wastewater ﬂow rates between 0.01and 0.5MGD.As seen in Figure 12.3,raw wastewater is ﬁrst screened before entering the oxidation ditch.Depending on the system size and manufacturer type,a grit chamber may be required.Once inside the ditch,the wastewater is aerated with mechanical surface or submersible aerators (depending on manufacturer design)that pro-pel the mixed liquor around the channel at velocities high enough to prevent solids depo-sition.The aerator ensures that there is sufﬁcient oxygen in the ﬂuid for the microbes and adequate mixing to ensure constant contact between the organisms and the food supply (24).Treated sewage moves to the settling tank or ﬁnal clariﬁer,where the biosolids and water separate.Wastewater then moves to other treatment processes while sludge is removed.Part of it is returned to the ditch as RAS,while the rest is removed from the process as the waste activated sludge (WAS).WAS is wasted either continuously or daily and must be stabilized before disposal or beneﬁcialreuse.Disinfection Clarification Screening/Grinding Oxidation Ditch Fig.12.3.Package oxidation ditch plant (22).520N.K.Shammas and L.K.Wang7.2.ApplicabilityIn general,package treatment plants are applicable for areas with a limited number of people and small wastewaterﬂows.They are most often used in remote locations such as trailer parks,highway rest areas,and rural areas.Oxidation ditches are suitable for facilities that require nutrient removal,have limitations owing to the nature of the site,or want a biological system that saves energy with limited use of chemicals unless required for further treatment.Oxidation ditch technology can be used to treat any type of wastewater that is responsive to aerobic degradation.In addition,systems can be designed for denitriﬁcation and phosphorous removal.Types of industries using oxidation ditches include:food processing,meat and poultry packing,breweries,pharmaceutical,milk processing,petrochemical,and numerous other types.Oxidation ditches are particularly useful for schools,small industries,housing developments,and small communities.Ultimately,this technology is most applicable for places that have a large amount of land available(22).7.3.Advantages and DisadvantagesSome advantages of package oxidation ditch plants are listed below(22):(a)Systems are well-suited for treating typical domestic waste,have moderate energy requirements,and work effectively under most types of weather.(b)Oxidation ditches provide an inexpensive wastewater treatment option with both low operationand maintenance costs and operational needs.(c)Systems can be used with or without clariﬁers,which affectsﬂexibility and cost.(d)Systems consistently provide high quality efﬂuent in terms of TSS,BOD,and ammonia levels.(e)Oxidation ditches have a relatively low sludge yield,require a moderate amount of operator skill,and are capable of handling shock and hydraulic loadings.The disadvantages include:(a)Oxidation ditches can be noisy owing to mixer/aeration equipment,and tend to produce odorswhen not operated correctly.(b)Biological treatment is unable to treat highly toxic waste streams.(c)Systems have a relatively large footprint.(d)Systems have lessﬂexibility should regulations for efﬂuent requirements change.7.4.Design CriteriaKey components of a typical oxidation ditch include a screening device,an inﬂuent dis-tributor(with some systems),a basin or channel,aeration devices(mechanical aerators,jet mixers,or diffusers,depending on the manufacturer),a settling tank orﬁnal clariﬁer(with some systems),and an RAS system(with some systems).These components are often built to share a common wall to reduce costs and save space.Concrete tanks are typically used when installing package plant oxidation ditches.This results in lower maintenance costs as concrete tanks do not require periodic repainting or sand blasting.Fabricated steel or a combination of steel and concrete can also be used for construction,depending on site conditions(24).Oxidation Ditch521 Table12.3Design criteria for package oxidation ditch plants(22)Parameter Design valueBOD loading(F/M),lb BOD5/lb MLVSS0.05–0.30Average oxygen requirement(@20◦C),lb/lb BOD5applied2–3Peak Oxygen requirement(@20◦C),lb/lb BOD5applied 1.5–2.0MLSS,mg/L3000–6000Detention time,h18–36V olumetric loading,lb BOD5/1,000ft35–30Table12.4Package oxidation ditch plants performance(22)Typical Efﬂuent Quality Ocoee WWTPWith2◦Clariﬁer With Filter%Removal Efﬂuent CBOD,mg/L0.105>97 4.8TSS,mg/L0.105>970.32TP,mg/L21NA NAN-NO3,mg/L NA NA>950.25 2◦=Secondary,NA=Not applicable.Table12.3lists typical design parameters for package oxidation ditch plants.The volume of the oxidation ditch is determined based on inﬂuent wastewater characteristics,efﬂuent discharge requirements,HRT,SRT,temperature,mixed liquor suspended solids(MLSS),and pH.It may be necessary to include other site speciﬁc parameters to design the oxidation ditch as well.Some oxidation ditches do not initially require clariﬁers,but can later be upgraded and expanded by adding clariﬁers,changing the type of process used,or adding additional ditches(25).7.5.PerformanceAlthough the manufacturer’s design may vary,most oxidation ditches typically achieve the efﬂuent limitations listed in Table12.4.Denitrifying oxidation ditches are capable of extremely high efﬁciencies.With modiﬁcations,some oxidation ditches can achieve TN removal to5mg/L.The3MGD oxidation ditch in Stonybrook,New York regularly maintains 97%nitrogen removal efﬁciency(9).Currently,the wastewater treatment plant in Ocoee,Florida accepts an averageﬂow of 1.1to1.2MGD.The city chose to use an oxidation ditch because it was an easy tech-nology for the plant staff to understand and implement.The facility is also designed for denitriﬁcation without the use of chemical additives.Nitrate levels consistently test at0.8to 1.0mg/L with limits of12mg/L(26).Table12.4indicates how well the Ocoee oxidation ditch performs.522N.K.Shammas and L.K.Wang Table12.5Costs for package oxidation ditch plants∗(22)Flow range,MGD Budget price,USD Budget cost,USD/gal0.00–0.0396,000 6.390.03–0.06109,100 2.420.06–1.10116,3000.211.10–1.70126,5000.101.70–2.50138,1000.07∗Dollars values adjusted form original1999(Cost Index=460.16)to2008(Cost Index=552.16);(Appendix A.extracted from US Army Corps of EngineersRef.27).7.6.CostsTable12.5lists budget cost estimates for various sizes of oxidation ditches(22).Operation and maintenance costs for oxidation ditches are signiﬁcantly lower than other secondary treatment processes.In comparison to other treatment technologies,energy requirements are low,operator attention is minimal,and chemical addition is not required.8.OPERATION AND MAINTENANCEOxidation ditches require relatively little maintenance compared to other secondary treat-ment processes.No chemicals are required in most applications,but metal salts can be added to enhance phosphorus removal.8.1.Residuals GeneratedPrimary sludge is produced if primary clariﬁers precede the oxidation ditch.Sludge produc-tion for the oxidation ditch process ranges from0.2to0.85kg TSS/kg(0.2to0.85lb TSS/lb) BOD applied(28).Typical sludge production is0.65kg TSS/kg of BOD(0.65lb TSS/lb of BOD).This is less than conventional activated sludge facilities because of long SRTs.8.2.Operating ParametersThe oxygen coefﬁcient for BOD removal varies with temperature and SRT.Typical oxygen requirements range from1.1to1.5kg of O2per kg of BOD removed(1.1to1.5lb of O2per lb of BOD removed)and4.57kg O2/kg TKN oxidized(4.57lb O2/lb TKN oxidized)(17). Oxygen transfer efﬁciency ranges from2.5to3.5lb/hp-h(16).9.DESIGN CONSIDERATIONS9.1.Input DataThe following data forﬂows and inﬂuent and efﬂuent characteristics shall be provided(1): (a)Wastewaterﬂow(average and peak).In case of high variability,a statistical distribution shouldbe provided.(b)Wastewater strength1.BOD5(soluble and total),mg/L2.COD and/or TOC(maximum and minimum),mg/L3.Suspended solids,mg/L4.V olatile suspended solids,mg/L5.Nonbiodegradable fraction of VSS,mg/L(c)Other characteristics1.pH2.Acidity and/or alkalinity,mg/L3.Nitrogen,mg/L(NH3or Kjeldahl)4.Phosphorus(total and soluble),mg/L5.Oils and greases,mg/L6.Heavy metals,mg/L7.Toxic or special characteristics(e.g.,phenols),mg/L8.Temperature,◦F or◦C(d)Efﬂuent quality requirements1.BOD5,mg/L2.SS,mg/LN,mg/L4.P,mg/L9.2.Design Parameters(a)Eckenfelder reaction rate constants and coefﬁcientsk=0.0007to0.002L/mg/h1.a=0.732.a =0.523.b=0.075/d4.b =0.15/d5.a o=0.77a=0.566.f=0.1407.f =0.53(b)F/M=0.03−0.1(c)V olumetric loading=10to40(d)t=18to36h(e)t s=20to30d(f)MLSS=4000to8000mg/L(mean=6000mg/L)(g)MLVSS=2800to5600mg/L(h)Q r/Q=0.5to1.0(i)lb O2/lb BOD r≥1.5(j)lb solids/lb BOD r≤0.2.(k)θ=1.0to1.03(l)Efﬁciency≥90%9.3.Design ProcedureThe following is a guide line that summarizes the design procedure(Eckenfelder Method) for an oxidation ditch(1,29–35)(a)Assume the following design parameters when known.1.Fraction of BOD synthesized(a)2.Fraction of BOD oxidized for energy(a )3.Endogenous respiration rate(b and b )4.Fraction of BOD5synthesized to degradable solids(a o)5.Nonbiodegradable fraction of VSS in inﬂuent(f)6.Mixed liquor suspended solids(MLSS)7.Mixed liquor volatile suspended solids(MLVSS)8.Temperature correction coefﬁcient(θ)9.Degradable fraction of the MLVSS(x )10.Food-to-microorganism ratio(F/M)11.Efﬂuent soluble BOD5(S e)(b)Adjust the BOD removal rate constant for temperaturek T=k20θ(T−20)(1)wherek T=rate constant for desired temperaturek20=rate constant at20◦Cθ=temperature correction coefﬁcientT=temperature,◦C(c)Determine the size of the aeration tankV=a o(S o−S e)Q avg/X V f b(2)whereV=aeration tank volume,MGa o=fraction of BOD5synthesized to degradable solidsS o=inﬂuent BOD5,mg/LS e=efﬂuent soluble BOD5,mg/LQ avg=Average wasteﬂow,MGDX V=MLVSS,mg/Lf =degradable fraction of the MLVSSb=endogenous respiration rate,1/d(d)Calculate the detention timet=(V/Q)24(3)wheret=detention time,hV=volume,MGQ=ﬂow,MGD(e)Assume the organic loading and calculate detention timet=(24S o)/X V(F/M)(4) wheret=detention time,hS o=inﬂuent BOD5,mg/LX V=volatile solids in raw sludge,mg/LF/M=organic loading(food-to-microorganism ratio)and select the larger of two detention times from d or e above(f)Determine the oxygen requirements allowing60%for nitriﬁcation during summerO2=[a S r Q avg+b X V V+0.6(4.57)(TKN)(Q avg)](8.34)(5)whereO2=oxygen required,lb/da =fraction of BOD oxidized for energyS r=BOD5removed,mg/LQ avg=average wasteﬂow,MGDb =endogenous respiration rate,1/dX V=MLVSS,mg/LV=aeration tank volume,MG4.57=parts oxygen required per part TKNTKN=total Kjeldahl nitrogen,mg/L(g)calculate oxygen requirement per lb BOD r(it should be≥1.5)lbO2/lb BOD r=O2/Q avg S r(8.34)(6)whereO2=oxygen required,lb/dQ avg=average wastewaterﬂow,MGDS r=BOD5removed,mg/L(h)Calculate sludge productionX V=8.34[a(S r)(Q)−(b)(X V)(V)−Q(SS)eff+Q(VSS)f +Q(SS−VSS)](7)whereX V volatile sludge produced,lb/da=fraction of BOD synthesizedS r=BOD5removed,mg/LQ=average wastewaterﬂow,MGDb=endogenous respiration rate,1/dX V=volatile solids in raw sludge,mg/LV=aeration tank volume,MG(SS)eff=efﬂuent suspended solids,mg/LVSS=volatile suspended solids in inﬂuent,mg/Lf =degradable fraction of the MLVSSSS=suspended solids in inﬂuent,mg/L(i)Calculate solids produced per pound of BOD removed(it should be≥1.5)lb solids/lb BOD r= X V/Q(S o−S e)8.34(8)whereX V=volatile sludge produced,lb/dQ=wasteﬂow,MGDS o=inﬂuent BOD5,mg/LS e=efﬂuent soluble BOD5,mg/L(j)Calculate the solids retention timet s=X a V(8.34)/ X V(9)wheret s=solids retention time,dX a=MLSS,mg/LV=volume of aeration tank,MGX V=volatile sludge produced,lb/d(k)Determine the efﬂuent soluble BOD5S e/S o=1/1+k X V t(10)whereS e=soluble efﬂuent BOD,mg/LS o=inﬂuent BOD5,mg/Lk=rate constant,L/mg/hX V=MLVSS,mg/Lt=aeration time,h(l)Calculate sludge recycle ratioQ r/Q avg=X a/X u−X a(11)whereQ r=volume of recycled sludge,MGDQ avg=averageﬂow,MGDX a=MLSS,mg/LX u=suspended solids concentration in returned sludge,mg/L(m)Calculate the nutrient requirements for nitrogen and PhosphorusN=0.123 X V(12)P=0.026 X V(13)where∆X V=sludge produced,lb/d9.4.Output Data(a)Aeration Tank(1)1.Reaction rate constant,L/mg/h2.Sludge produced per BOD removed3.Endogenous respiration rate(b,b )4.O2used per BOD removed5.Inﬂuent nonbiodegradable VSS6.Efﬂuent degradable VSS7.lb BOD/lb MLSS-d(F/M)8.Mixed liquor suspended solids(MLSS),mg/L9.Mixed liquor volatile suspended solids(MLVSS),mg/L10.Aeration time,h11.V olume of aeration tank,MG12.Oxygen required,lb/d13.Sludge produced,lb/d14.Nitrogen requirement,lb/d15.Phosphorus requirement,lb/d16.Sludge recycle ratio17.Solids retention time,d(b)Mechanical Aeration System1.Standard transfer efﬁciency,lb O2/hp-h2.Operating transfer efﬁciency,lb O2/hp-h3.Horsepower required,hp(c)Diffused Aeration System1.Standard transfer efﬁciency,%2.Operating efﬁciency,%3.Required airﬂow,cfm/1000ft310.COSTSThe basin volume and footprint required for oxidation ditch plants have traditionally been very large compared with other secondary treatment rger footprints result in higher capital costs,especially in urbanized locations where available land is very expensive. Vertical reactors,in which processﬂow travels downward through the reactor,are generally more expensive than traditional horizontal reactors.However,because they require less land than more conventional horizontal reactors,they can signiﬁcantly reduce overall capital costs where land costs are high.The cost of an oxidation ditch plant varies depending on treatment capacity size,design efﬂuent limitations,land cost,local construction costs,and other site speciﬁc factors.Con-struction capital costs for ten plants were evaluated by US EPA in1991(17),with construction costs,in2008Dollars,ranging from USD0.73to4.46/L/d(USD2.76to16.87/gpd)treated. The cost values have been adjusted from the original1991(Cost Index392.35)to2008(Cost Index552.16)using the Utilities Cost index(Appendix A.Ref.27).Recent information obtained from manufacturers on facilities ranging3,785to25,740m3/d (1.0MGD to6.8MGD)indicates that construction capital costs(adjusted from original1999 to2008Dollars)of oxidation ditch plants range from USD0.80to1.32/L/d(USD3.00to 4.80/gpd).For example,the Blue Heron Water Reclamation Facility in Titusville,Florida(36) a15,142m3/d(4.0MGD)oxidation ditch and sludge handling facility which began operation in1996,was constructed for about USD0.96/L/d(USD3.60/gpd).The facility features a multi-stage biological nutrient removal process and a sophisticated Supervisory Control and Data Acquisition System(SCADA)control system.。

水处理英文文献

introductionNew technology creates interest in the municipal wastewater treatment sector because it serves a new or existing need in acreative manner and is therefore deemed innovative. In fact, thedefinitionof new technology is synonymous with technologicalinnovation. Innovativewastewater treatment technologies aredeveloped to respond to changing regulatory requirements,increase efficiency, and enhance sustainability or to reduce capitalor operating costs.The latest U.S. Environmental Protection Agency (Washington,D.C.) (U.S. EPA) needs survey (U.S. EPA, 2010) establishes totalneeds for wastewater treatment (secondary and advanced) over thenext two decades at $105 billion out of the total for wastewater(all categories) at $298 billion, a staggering amount.New technology introductions can mitigate the costs ofwastewater treatment for the wastewater industry. However, newwastewater treatment process introduction faces significantobstacles in theNorth American marketplace. The risks involvedwith these introductions means that many municipalities will notparticipate in them, waiting instead for others to be "first."Municipal officials and consulting firms generally are not rewarded for assuming such risks, and often they will be resistant,even if the risk of catastrophic failure is small. This slows the pace of new process introduction and reduces the aggregate benefits of new technology development.In this paper, the writer draws on his and Brown and Caldwell's experience with new technology introduction, both from the point of view of the innovator/developer originating the technology, as well as from the point of view of an adopter, when evaluating and recommending new technologies to others. Beyond the use of personal knowledge and observations, marketing theory is applied to the analysis.Finally, the assessment is extended to identify measures that have increased the capture of benefits from the introduction of the new technology. It includes recommended measures that will reduce the risk involved in new technology applications, such as increased transparency of information, provision of independent evaluations of technologies, and mechanisms for sharing risk more broadly. Theories of New Technology IntroductionAbout a decade ago it struck the writer that wastewater treatment innovations followed a life cycle that resembles an S curve, as shown in Figure 1.Here the new process life cycle focus was on its technology development aspects,as it moved from pilot to demonstration scale, its first full-scale applications, and its subsequent refinement, until a plateau of mature technology status was reached. The writer applied the curve to several applications he knew intimately, while a colleague contributed others. Indeed, it was found that the S curve seemed a reasonable fit for all of those cases for which there were no marketplace disruptions. The theory was first presented at an MBR conference focused on industrial applications (Melcer and Parker, 2003). The concept of a product life cycle is well known in business in the sales of products and services (e.g., Rink and Swan, 1979), although its focus has not been on the stage of technology development. Instead of an S curve, it has been presented as a plot of sales per reporting period(see Figure 2).A different type of S curve for new technology penetration had earlier been discovered by social scientists. Developed from the purchaser's point of view, it was found that new technology diffusion followed an S curve. This was first observed in the forties where the rate of hybrid corn seed adoption was followed in two Iowa farming communities. It has since been used in many applications. The full development of the concept can be found in the widely-used text by Everett Rogers first published in 1962 (the current fifth edition is Rogers, 2003). Figure 3 shows Rogers' conceptualization of the diffusion of technology. The curve is。

水污染处理文献综述英文

Application of multi—soil-layer system （MSL) in ruralwastewater treatmentAbstract：with the continuous improvement of living in rural farmers, the water consumption of residents is increasing，rural sewage emissions will continue to increase，if not treat effectively，the water environment in rural areas will be serious deteriorated，and influence the life quality of rural residents. In this case this paper presents a decentralized sewage treatment system，multi-soil-layer system technology （MSL) application in the rural sewage treatment，this paper summarizes the new technology, you can better understand and practice，especially in the developing countries where is in need of this technology. In the foreseeable future，it can protect public health and the sustainable development of the environment，and it also provides a new way for rural sewage treatment。

水污染处理文献综述英文

Application of multi-soil-layer system (MSL) in ruralwastewater treatmentAbstract:with the continuous improvement of living in rural farmers, the water consumption of residents is increasing, rural sewage emissions will continue to increase, if not treat effectively, the water environment in rural areas will be serious deteriorated, and influence the life quality of rural residents. In this case this paper presents a decentralized sewage treatment system, multi-soil-layer system technology (MSL) application in the rural sewage treatment, this paper summarizes the new technology, you can better understand and practice, especially in the developing countries where is in need of this technology. In the foreseeable future, it can protect public health and the sustainable development of the environment, and it also provides a new way for rural sewage treatment.Key words: rural sewage; multi-soil-layering system; distributed1.IntroductionIn recent years, with the continuous development of economy, people's living standards continue to improve, rural economic development is also very rapid, but the rural economic development and environmental development is not synchronized, serious rural water pollution.While high technical sewage treatment plants, such as centralized sewage treatment plants are involved in large investment costs, high operating costs,Because of economic constraints, such systems are less suitable for livestock farms and small communities in rural areas. While the multi-media-soil layer system(MSL) sewage treatment system, this decentralized sewage treatment system, it has less investment, low operating costs, high handling load. Besides, the utility model overcomes the defects of the prior soil percolation which is easy to be blocked from the space structure.The sewage treatment system is one kind of the purification technology of sewerage treatment soil developed in Japan in twentieth Century, the soil system will be modularized, and the module is set up around the water in the soil layer to avoid clogging, and adding natural organic materials to soil modules can improve the purification ability of the system.The MSL system consists of a Permeable layer (PL) and a soil mixing layer block (SMB),The Permeable layer is usually composed oflarger particles fillers such as gravel, pumice, perlite and zeolite.Higher porosity can effectively prevent clogging of the soil water layer.At the same time, the formation of aerobic environment is conducive to organic degradation.The mixed layer soil is mainly packing soil mixed with other 20%-30% other materials such as activated carbon, wood, iron and other material or soil with local resources.The organic material added in the soil mixed layer can improve the biological decomposition and adsorption capacity of the system, and can also improve the supply of hydrogen in the process of nitrogen removal and promote the removal of nitrogen.There are many researches on MSL system treating urban sewage, livestock wastewater and river water at home and abroad.Researchers in China, Ye Hai et al[1] studied the effect of surface load on polluted river water treated by multi-soil-layer system.Song Ying[2]had studied the treatment effect of multi medium soil infiltration system for turtle breeding wastewater.Zou Jun[3]also pointed out that multi-soil-layer material selection will have a certain impact on the domestic sewage treatment efficiency.In foreign countries, especially in Japan, Thailand and Indonesia, MSL systems have been used to handle various types of wastewater, but the domestic of this technology in sewage treatment in rural areas there is no comprehensive study,This article through to the MSL system technology processing rural domestic sewage research, inorder to provide some technical support for the MSL system in the practical application of rural sewage treatment.2.1characteristics of rural sewageFor a long time,China's pollution control on rural attention and investment far less than the city,96% of the villages without drainage pipe network and sewage treatment system,The random discharge of domestic sewage has become one of the main reasons for the deterioration of water quality in the basin, and is also an important factor causing the rural water environment pollution and lake eutrophication.At the same time, it seriously affects the safety of production and living in the rural areas, and seriously affects the economic development.The main features of rural sewage in China are:(1)The amount is huge and increases year by year.Statistics show that in 2002.There are 3.205 million tons of national rural domestic sewage daily emissions.The total nitrogen emission is about 283.1t, total phosphorus daily emission is about 56.6t, basically without any treatment directly discharged.(2)Water quality and water quantity fluctuation are huge.Rural sewage water is not stable, different periods have different water quality, generally do not contain heavy metals and toxic and harmful substances, but contains more synthetic detergent and bacteria, viruses.(3)More sources.In addition to human feces, kitchen generated sewage, there are household cleaning, domestic waste landfill leachate generated sewage, which will then enter the river part of the sewage, will cause greater pollution.(4)Low treatment rate.Part of the system can not run low temperature, rural sewage daily variation coefficient and seasonal variation coefficient, the system a few time high load operation, if there is little sewage, it will stop running [4].(5)Wide and scattered.Scattered geographical distribution of villages caused sewage dispersion and it is difficult to collect.2.2 the main source of rural sewageRural sewage refers to the formation of sewage of the rural areas in the life and production process, including rural production wastewater and rural domestic sewage two aspects.Rural domestic sewage refers to the residents living in the process of toilet discharge of sewage, bath, laundry and kitchen sewage, etc.Rural production sewage refers to livestock and poultry breeding, aquaculture, agricultural products processing and other high concentration of organic wastewater.Because China's rural living is scattered, rural domestic sewage showed a small amount and wide ck of appropriate sewage collection, treatment facilities, domestic sewage without treatment will be free to discharge, the health of rural residents to bring greater harm.At the sametime, rural sewage production also poses a greater threat to the rural ecological environment.2.3main technologies of decentralized domestic sewage treatmentBeginning in 1970s, Japan, the United States, Europe and other developed countries on the use of decentralized sewage treatment of rural sewage treatment, has accumulated a lot of experience, achieved good results.The United States since the mid-20th century began the construction of rural sewage treatment facilities, in 1972 promulgated the first complete clean water, then according to the distributed processing technology in 2002 promulgated the decentralized sewage treatment system application manual [5].1987, In Denmark promulgated a decentralized sewage treatment guidelines[6].Germany from 2003 to implement the decentralized needle infrastructure system project research, use membrane bioreactor purification to treat remote rural sewage[7]. Australia proposed a sewage treatment land use system [8].While research and application of rural sewage decentralized treatment in China began in late 1980s,Compared with developed countries and regions, there are still many gaps in laws and regulations system, technical standard system and management and service system.In recent years, domestic scholars have done a lot of research on rural domestic sewage,and puts forward some mature processing technology, including aerobic biological treatment, anaerobic biological treatment technology, soil infiltration technique andphysical and chemical processing technology etc.There are many scholars in the multi-soil-layer system improvement and application development of the Japanese, it has also done a lot of research, some scholars found through experiments: to earthworm soil infiltration layer can also solve the problem of blockage of MSL system, but also can guarantee the winter operation effect in winter [9-10].2.4 Multi-soil-layer system (MSL) technology2.4.1Structural characteristics of multi-media-soil layer systemMulti-soil-layer treatment (MSL) system is a kind of land sewage treatment system.Mainly composed of Permeable layer (PL) and a soil mixing layer block (SMB),From top to bottom are waterproof layer, gravel layer, soil layer and mixed layer (two alternately arranged), in addition, the MSL technology has a certain terrain fall from the inlet to the outlet, mainly by the drop let water can automatically flow in the system, at the same time to purify [11].2.4.2Purification mechanism of multi-soil-layer systemWastewater contains high concentrations of BOD, COD, ammonia nitrogen, phosphate ions and organic matter.When the wastewater into the MSL system, the organic matter in wastewater can be adsorbed on the surface of zeolite and soil through physical and chemical effects, followed by decomposition of soil layer in microorganism, and phosphorus removal is mainly through the soil layer of iron is oxidized toferric hydroxide after the formation of insoluble iron, then adsorption in wastewater the formation of phosphate coprecipitation.Nitrogen removal is mainly through nitrification and denitrification by ammonia ion, and finally reduced to nitrogen discharge system.2.4.3Advantages of multi-soil-layer systemMulti-media-soil layer system is used to treat wastewater from traditional soil infiltration system.It has the disadvantages of low treatment load, large ground, easy to block nitrogen and phosphorus removal and other shortcomings [12].The MSL system with "soil modular" as the core concept, its unique brick type internal structure can form a plurality of aerobic and anaerobic environment in order to promote the removal of pollutants,Among them, the permeable layer greatly improves the water permeability of the system to prevent clogging, adding natural materials in the soil increases the purification capacity of the system.3.ConclusionsWith the economic reform and development, China's environmental awareness is also improving, water pollution in rural areas have also obtained more and more attention,The MSL system applicable to the small population, scattered in rural areas, the decentralized sewage treatment system can be widely installed and used in the rural society, especially in rural areas of developing countries such as Chinese, Chinese is in need of such technology, sustainable development can protect thepublic health and the environment.4.Reference[1] Ye Hai Ye et al. Effect of surface load on polluted river water treated by multi-soil-layer system[J]. China water supply and drainage, 2012,28 (19): 74-77[2]Ying Song et al.Treatment of turtle aquaculture effluent by an multi-soil-layersystem[J].Journal of Zhejiang University Science B.2015,16(2):145-154[3]Zou Jun, Chen Xin et al. Effect of material selection of multi-soil-layer systemon domestic wastewater treatment efficiency[J]. Journal of ecology and rural environment, 2010,26 (1): 14-18[4]Zhang Keqiang et al. Rural sewage treatment technology[M]Beijing: ChinaAgricultural Science and Technology Press, 2006.10[5] Chen Jinming et al.Policy and experience of managing decentralized wastewatertreatment systems in the United States [J]. China water supply and drainage, 2004,20 (6): 104-106[6] Hans B.Danish guidelines for small-scale constructed wetland systems for onsitetreatment of domestic sewage[C].Proceedings of the 9th International Conference on Wetland Systems for Water Pollution Control, Avignon, France,2004:1-8[7] Li Wushuang, Wang Hongyang. Status and treatment technology of ruraldecentralized domestic wastewater [J]. Tianjin Agricultural Sciences, 2008,14 (6): 75-77[8] Zhang Jiawei, Zhou Zhiqin. Application of decentralized treatment technology forrural domestic sewage [J]. environmental science and management, 2011,36 (1): 95-99[9] Wang Xixi, Guo Feihong, et al. A new improved capillary infiltration ditch fordomestic wastewater treatment. [J].environmental chemistry,2011,30(3): 721-722 [10]Zhang Xiaowei, Li Jianchao, et al. Experimental study on earthworm enhancedland treatment of rural wastewater [J]. Journal of agro environmental science,2009,28 (6): 1225-1229[11]Hu Hongqi, Yang Yong et al. Analysis of practical application of two efficientrural sewage treatment technologies [J]. Heilongjiang environmental bulletin, 2016, 40 (1): 20-24[12] Xin Chen et al.An introduction of a multi-soil-layering system:a novel greentechnology for wastewater treatment in rural areas[J].Water and Environment Journal.2009:255-262。

水污染处理文献综述英文

Application of multi-soil-layer system (MSL) in ruralwastewater treatmentAbstract:with the continuous improvement of living in rural farmers, the water consumption of residents is increasing, rural sewage emissions will continue to increase, if not treat effectively, the water environment in rural areas will be serious deteriorated, and influence the life quality of rural residents. In this case this paper presents a decentralized sewage treatment system, multi-soil-layer system technology (MSL) application in the rural sewage treatment, this paper summarizes the new technology, you can better understand and practice, especially in the developing countries where is in need of this technology. In the foreseeable future, it can protect public health and the sustainable development of the environment, and it also provides a new way for rural sewage treatment.Key words: rural sewage; multi-soil-layering system; distributed1.IntroductionIn recent years, with the continuous development of economy, people's living standards continue to improve, rural economic development is also very rapid, but the rural economic development and environmental development is not synchronized, serious rural water pollution.While high technical sewage treatment plants, such as centralized sewage treatment plants are involved in large investment costs, high operating costs,Because of economic constraints, such systems are less suitable for livestock farms and small communities in rural areas. While the multi-media-soil layer system(MSL) sewage treatment system, this decentralized sewage treatment system, it has less investment, low operating costs, high handling load. Besides, the utility model overcomes the defects of the prior soil percolation which is easy to be blocked from the space structure.The sewage treatment system is one kind of the purification technology of sewerage treatment soil developed in Japan in twentieth Century, the soil system will be modularized, and the module is set up around the water in the soil layer to avoid clogging, and adding natural organic materials to soil modules can improve the purificationability of the system.The MSL system consists of a Permeable layer (PL) and a soil mixing layer block (SMB),The Permeable layer is usually composed of larger particles fillers such as gravel, pumice, perlite and zeolite.Higher porosity can effectively prevent clogging of the soil water layer.At the same time, the formation of aerobic environment is conducive to organic degradation.The mixed layer soil is mainly packing soil mixed with other 20%-30% other materials such as activated carbon, wood, iron and other material or soil with local resources.The organic material added in the soil mixed layer can improve the biological decomposition and adsorption capacity of the system, and can also improve the supply of hydrogen in the process of nitrogen removal and promote the removal of nitrogen.There are many researches on MSL system treating urban sewage, livestock wastewater and river water at home and abroad.Researchers in China, Ye Hai et al[1] studied the effect of surface load on polluted river water treated by multi-soil-layer system.Song Ying[2]had studied the treatment effect of multi medium soil infiltration system for turtle breeding wastewater.Zou Jun[3]also pointed out that multi-soil-layer material selection will have a certain impact on the domestic sewage treatment efficiency.In foreign countries, especially in Japan, Thailandand Indonesia, MSL systems have been used to handle various types of wastewater, but the domestic of this technology in sewage treatment in rural areas there is no comprehensive study,This article through to the MSL system technology processing rural domestic sewage research, in order to provide some technical support for the MSL system in the practical application of rural sewage treatment.2.1characteristics of rural sewageFor a long time,China's pollution control on rural attention and investment far less than the city,96% of the villages without drainage pipe network and sewage treatment system,The random discharge of domestic sewage has become one of the main reasons for the deterioration of water quality in the basin, and is also an important factor causing the rural water environment pollution and lake eutrophication.At the same time, it seriously affects the safety of production and living in the rural areas, and seriously affects the economic development.The main features of rural sewage in China are:(1)The amount is huge and increases year by year.Statistics show that in 2002.There are 3.205 million tons of national rural domestic sewage daily emissions.The total nitrogen emission is about 283.1t, total phosphorus daily emission is about 56.6t, basically without any treatmentdirectly discharged.(2)Water quality and water quantity fluctuation are huge.Rural sewage water is not stable, different periods have different water quality, generally do not contain heavy metals and toxic and harmful substances, but contains more synthetic detergent and bacteria, viruses.(3)More sources.In addition to human feces, kitchen generated sewage, there are household cleaning, domestic waste landfill leachate generated sewage, which will then enter the river part of the sewage, will cause greater pollution.(4)Low treatment rate.Part of the system can not run low temperature, rural sewage daily variation coefficient and seasonal variation coefficient, the system a few time high load operation, if there is little sewage, it will stop running [4].(5)Wide and scattered.Scattered geographical distribution of villages caused sewage dispersion and it is difficult to collect.2.2 the main source of rural sewageRural sewage refers to the formation of sewage of the rural areas in the life and production process, including rural production wastewater and rural domestic sewage two aspects.Rural domestic sewage refers to the residents living in the process of toilet discharge of sewage, bath,laundry and kitchen sewage, etc.Rural production sewage refers to livestock and poultry breeding, aquaculture, agricultural products processing and other high concentration of organic wastewater.Because China's rural living is scattered, rural domestic sewage showed a small amount and wide ck of appropriate sewage collection, treatment facilities, domestic sewage without treatment will be free to discharge, the health of rural residents to bring greater harm.At the same time, rural sewage production also poses a greater threat to the rural ecological environment.2.3main technologies of decentralized domestic sewage treatmentBeginning in 1970s, Japan, the United States, Europe and other developed countries on the use of decentralized sewage treatment of rural sewage treatment, has accumulated a lot of experience, achieved good results.The United States since the mid-20th century began the construction of rural sewage treatment facilities, in 1972 promulgated the first complete clean water, then according to the distributed processing technology in 2002 promulgated the decentralized sewage treatment system application manual [5].1987, In Denmark promulgated a decentralized sewage treatment guidelines[6].Germany from 2003 to implement the decentralized needle infrastructure system project research, use membrane bioreactor purification to treat remote rural sewage[7].Australia proposed a sewage treatment land use system [8].While research and application of rural sewage decentralized treatment in China began in late 1980s,Compared with developed countries and regions, there are still many gaps in laws and regulations system, technical standard system and management and service system.In recent years, domestic scholars have done a lot of research on rural domestic sewage,and puts forward some mature processing technology, including aerobic biological treatment, anaerobic biological treatment technology, soil infiltration technique and physical and chemical processing technology etc.There are many scholars in the multi-soil-layer system improvement and application development of the Japanese, it has also done a lot of research, some scholars found through experiments: to earthworm soil infiltration layer can also solve the problem of blockage of MSL system, but also can guarantee the winter operation effect in winter [9-10].2.4 Multi-soil-layer system (MSL) technology2.4.1Structural characteristics of multi-media-soil layer systemMulti-soil-layer treatment (MSL) system is a kind of land sewage treatment system.Mainly composed of Permeable layer (PL) and a soil mixing layer block (SMB),From top to bottom are waterproof layer, gravel layer, soil layer and mixed layer (two alternately arranged), in addition, the MSL technology has a certain terrain fall from the inlet tothe outlet, mainly by the drop let water can automatically flow in the system, at the same time to purify [11].2.4.2Purification mechanism of multi-soil-layer systemWastewater contains high concentrations of BOD, COD, ammonia nitrogen, phosphate ions and organic matter.When the wastewater into the MSL system, the organic matter in wastewater can be adsorbed on the surface of zeolite and soil through physical and chemical effects, followed by decomposition of soil layer in microorganism, and phosphorus removal is mainly through the soil layer of iron is oxidized to ferric hydroxide after the formation of insoluble iron, then adsorption in wastewater the formation of phosphate coprecipitation.Nitrogen removal is mainly through nitrification and denitrification by ammonia ion, and finally reduced to nitrogen discharge system.2.4.3Advantages of multi-soil-layer systemMulti-media-soil layer system is used to treat wastewater from traditional soil infiltration system.It has the disadvantages of low treatment load, large ground, easy to block nitrogen and phosphorus removal and other shortcomings [12].The MSL system with "soil modular" as the core concept, its unique brick type internal structure can form a plurality of aerobic and anaerobic environment in order to promote the removal of pollutants,Among them, the permeable layer greatly improvesthe water permeability of the system to prevent clogging, adding naturalmaterials in the soil increases the purification capacity of the system.3.ConclusionsWith the economic reform and development, China's environmentalawareness is also improving, water pollution in rural areas have alsoobtained more and more attention,The MSL system applicable to thesmall population, scattered in rural areas, the decentralized sewagetreatment system can be widely installed and used in the rural society,especially in rural areas of developing countries such as Chinese, Chineseis in need of such technology, sustainable development can protect thepublic health and the environment.4.Reference[1] Ye Hai Ye et al. Effect of surface load on polluted river water treated by multi-soil-layer system[J]. China water supply and drainage, 2012,28 (19): 74-77[2]Ying Song et al.Treatment of turtle aquaculture effluent by an multi-soil-layersystem[J].Journal of Zhejiang University Science B.2015,16(2):145-154[3]Zou Jun, Chen Xin et al. Effect of material selection of multi-soil-layer systemon domestic wastewater treatment efficiency[J]. Journal of ecology and rural environment, 2010,26 (1): 14-18[4]Zhang Keqiang et al. Rural sewage treatment technology[M]Beijing: ChinaAgricultural Science and Technology Press, 2006.10[5] Chen Jinming et al.Policy and experience of managing decentralized wastewatertreatment systems in the United States [J]. China water supply and drainage, 2004,20 (6): 104-106[6] Hans B.Danish guidelines for small-scale constructed wetland systems for onsitetreatment of domestic sewage[C].Proceedings of the 9th International Conference on Wetland Systems for Water Pollution Control, Avignon, France,2004:1-8[7] Li Wushuang, Wang Hongyang. Status and treatment technology of ruraldecentralized domestic wastewater [J]. Tianjin Agricultural Sciences, 2008,14 (6): 75-77[8] Zhang Jiawei, Zhou Zhiqin. Application of decentralized treatment technology forrural domestic sewage [J]. environmental science and management, 2011,36 (1):95-99[9] Wang Xixi, Guo Feihong, et al. A new improved capillary infiltration ditch fordomestic wastewater treatment. [J].environmental chemistry,2011,30(3): 721-722[10]Zhang Xiaowei, Li Jianchao, et al. Experimental study on earthworm enhancedland treatment of rural wastewater [J]. Journal of agro environmental science,2009,28 (6): 1225-1229[11]Hu Hongqi, Yang Yong et al. Analysis of practical application of two efficientrural sewage treatment technologies [J]. Heilongjiang environmental bulletin, 2016, 40 (1): 20-24[12] Xin Chen et al.An introduction of a multi-soil-layering system:a novel greentechnology for wastewater treatment in rural areas[J].Water and Environment Journal.2009:255-262。

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氧化沟工艺在污水处理中的应用和发展摘要：本文主要阐叙了Carrousel氧化沟的结构、工艺机理、运行过程中存在的问题和相应的解决办法。

最后，介绍了Carrousel氧化沟的最新的研究进展并指出了未来的主要研究方向。

关键词：Carrousel氧化沟除磷脱氮结构机理1、前言氧化沟又名连续环曝气池，是活性污泥法的一种变形。

氧化沟处理工艺在20世纪50年代由荷兰卫生工程研究所研制成功的。

自从1954年在荷兰的首次投入使用以来。

由于其出水水质好、运行稳定、管理方便等技术特点，已经在国内外广泛的应用于生活污水和工业污水的治理。

目前应用较为广泛的氧化沟类型包括：帕斯维尔氧化沟、卡鲁塞尔氧化沟，奥尔博氧化沟、T型氧化沟、DE型氧化沟和一体化氧化沟。

这些氧化沟由于在结构和运行上存在差异，因此各具特点。

本文将主要介绍Carrousel氧化沟的的结构、机理、存在的问题及其最新发展。

2、Carrousel氧化沟的结构Carrousel氧化沟是1967年由荷兰的DHV公司开发研制。

在原Carrouse氧化沟的基础上DHV公司和其在美国的专利特许公司EIMCO又发明了Carrousel 2000系统，实现了更高要求的生物脱氮和除磷功能。

至今世界上已有850多座Carrousel氧化沟和Carrousel 2000系统正在运行。

Carrousel氧化沟使用定向控制的曝气和搅动装置，向混合液传递水平速度，从而使被搅动的混合液在氧化沟闭合渠道内循环流动。

因此氧化沟具有特殊的水力学流态，既有完全混合式反应器的特点，又有推流式反应器的特点，沟内存在明显的溶解氧浓度梯度。

氧化沟断面为矩形或梯形，平面形状多为椭圆形，沟内水深一般为2.5~4.5m，宽深比为2:1，亦有水深达7m的，沟内水流平均流速为0.3m/s。

氧化沟的曝气混合设备有表面、曝气转刷或转盘，射流曝气池、导管式曝气器和提升管曝气机等，近年来配合使用的还有水下推动器。

3、Carrousel氧化沟的机理3.1 Carrousel氧化沟处理污水的机理最初的普通Carrousel氧化沟的工艺中污水直接与回流污泥一起进入氧化沟系统。

表面曝气机使混合液中溶解氧DO的浓度增加到大2~3mg/L。

在这种充分掺氧的条件下，微生物得到足够的溶解氧来去除BOD；同时，氮也被氧化成硝酸盐和亚硝酸盐，此时，混合液处于有氧状态，在曝气机下游，水流由曝气去的湍流状态变成之后的平流状态，水流维持在最小流速，保证活性污泥处于悬浮状态（平均流速大于0.3m/s）。

微生物的氧化过程消耗了水中溶解氧，直到DO值降为0，混合液呈缺氧状态。

经过缺氧区的反硝化作用，混合液进入有氧区，完成一次循环。

该系统中，BOD降解是一个连续过程，硝化作用和反硝化作用发生在同一池中。

由于结构的限制，这种氧化沟虽然可以有效去除BOD，但除磷脱氮的能力有限。

3.2 Carrousel氧化沟除磷脱氮的影响因素影响Carrousel氧化沟除磷夫人因素主要是污泥龄、硝酸盐浓度及基质浓度。

研究表明，当污泥龄为8~10d时活性污泥中最大磷含量为其干污泥量的4%，为异养菌质量的11%，但当污泥龄超过15d时污泥中最大含磷量明显下降，反而达不到最大除磷效果。

因此，一味延长污泥龄是没有必要的，宜在8~15天范围内选用。

同时，高硝酸盐浓度和低基质浓度不利于除磷过程。

4、Carrousel氧化沟存在的问题及解决办法尽管Carrousel氧化沟具有出水水质好、抗冲击负荷能力强、除磷脱氮效率高、污泥易稳定、能耗省、便于自动化控制等优点。

但是，在实际的运行过程中，仍存在一系列问题。

4.1污泥膨胀问题当废水中的碳水化合物较多，N、P含量不平衡，PH值偏低，氧化沟中污泥负荷过高，溶解氧浓度不足，排泥不畅等易引起丝状菌性污泥膨胀，非丝状菌性污泥膨胀主要发生在废水水温较低而污泥负荷较高时。

微生物的负荷高，细菌吸取了大量的营养物质，由于水温低，代谢速度较慢，积贮起大量高粘性的多糖类物质，使活性污泥的表面附着水大大增加，SVI 值很高，形成污泥膨胀。

针对污泥膨胀的起因，可以采取不同的对策：由缺氧、水温高造成的，可加大曝气量或降低进水量以减轻负荷，或适当降低MLSS（控制污泥回流量），使需氧量减少；如污泥负荷过高，可以提高MLSS，以调整负荷，必要时可停止进水，闷曝一段时间；可通过投加氮肥、磷肥，调整混合液中的营养物质平衡（BOD5：N:P=100:5:1）；PH值过低，可投加石灰调节；漂白粉和液氯，能抑制丝状菌繁殖，控制结合水性污泥膨胀。

4.2泡沫问题由于进水中带有大量油脂，处理系统不能完全有效地将其除去，部分油脂富集于污泥中，经转刷充氧搅拌，产生大量泡沫；泥龄偏长，污泥老化，也易产生泡沫。

用表面喷淋水或除沫剂去除泡沫，常用除沫剂有机油、煤油、硅油，投加量为0.5~1.5mg/L。

通过增加曝气池污泥浓度或适当减少曝气量，也能有效控制泡沫产生。

当废水中含表面活性物质较多时，易预先用泡沫分离或其他方法去除。

另外也可考虑增设一套除油装置。

但最重要的是要加强水源管理，减少含油过高废水及其有毒废水的进入。

4.3污泥上浮问题当废水中含油量过大，整个系统泥质变轻，在操作过程中不能很好控制其在二沉池的停留时间，易造成缺氧，产生污泥上浮；当曝气时间过长，在池中发生高度消化作用，使硝酸盐浓度过高，在二沉池易发生反硝化作用，产生氮气，使污泥上浮；另外，废水中含油量过大，污泥可能挟油上浮。

发生污泥上浮后应暂停停水，打碎或清除污泥，判明原因，调整操作。

污泥沉降性差，可投加混凝剂或惰性物质，改善沉淀性；如进水负荷大应减少进水量；如污泥颗粒细小可降低曝气机转速；如发现反硝化，应减小曝气量，增大回流或排泥量；如发现污泥腐化，应加大曝气量，清除积泥，并设法改善内水力条件。

4.4 流速不均及污泥沉积问题在Carrousel氧化沟中，为了获得其他独特的混合和处理效果，混合液必须以一定的流速在沟内循环流动。

一般认为，最低流速应为0.15m/s，不发生沉积的平均流速应达到0.3~0.5m/s。

氧化沟的曝气设备一般为曝气转刷和曝气转盘，转刷的浸没深度为250~300mm，转盘的浸没深度为480~530mm,与氧化沟水深（3.0~3.6m)相比，转刷只占了水深的1/10~1/12,转盘也只占了1/6~1/7,因此造成氧化沟上部流速较大（约为0.8m~1.2m,甚至更大），而底部流速很小，致使沟底大量积泥（有时积泥厚度达1m),大大减少了氧化沟的有效容积，降低了处理效果，影响出水水质。

加装上、下游导流板是改善流速分布、提高充氧能力的有效方法和最方便的措施。

上流导流板在距转盘轴心4.0处，导流板高度为水深的1/5~1/6，并垂直于水面安装：下游导流板安装在距转盘轴心3.0m处。

导流板的材料可以用金属或玻璃钢，但以玻璃钢为佳。

导流板与其改善措施相比，不仅不会增加动力消耗和运转成本，而且还能够较大幅度地提高充氧能力和理论动力效率。

另外，通过在曝气机上游设置水下推动器也可以对曝气转刷底部低速区德尔混合液循环流动起到积极作用，从而解决氧化沟底部流速低、污泥沉积的问题。

设置水下推动器专门用于推动混合液可以使氧化沟的运行方式更加灵活，对于节约资源、提高效率具有十分重要的意义。

5、Carrousel氧化沟的发展由于污水处理标准中对除磷脱氮的要求越来越严格，Carrousel氧化沟也得到了进一步的发展。

目前，研究及应用较多的包括以下两种类型：微孔曝气型Carrousel2000系统、Carrousel3000系统。

5.1 微孔曝气型Carrousel 2000系统微孔曝气型Carrousel 2000系统采用微孔曝气（供养设备为鼓风机），微孔曝气器可产生大量直径为1mm左右的微小气泡，这大大提高了气泡的表面积，使得在池容积一定的情况下氧转移总量增大。

根据目前鼓风机生产厂家的技术能力，池的有效水深最大可达8m，因此可根据不同的工艺要求选择合适的水深。

传统氧化沟的推流是利用转刷、转碟或倒伞形表爆机实现的，其设备利用率低、动力消耗大。

微孔曝气型Carrousel 2000系统则采用了水下推流的方式，即把潜水推进器叶轮产生的推动力直接作用于水体，在起推流作用的同时又可有效防止污泥的沉降。

因此，采用潜水推进器既降低了动力消耗，又使污水得到了充分地混合。

5.2 Carrousel 3000系统Carrousel 3000系统是在Carrousel 2000系统前再加上一个生物选择区。

该生物选择区是利用高有机负荷筛选菌种，抑制丝状菌的生长，提高各污染物的去除率，其后的工艺原理同Carrousel 2000系统。

Carrousel 3000系统的较大提高表现在：一是增加了池深，可达7.5~8m，同心圆式，池壁共用，减少了占地面积，降低造价同时提高了耐低温能力；而是曝气设备的巧妙设计，曝气机下装导流筒，抽吸缺氧的混合液，采用水下推进器解决流速问题；三是使用了先进的曝气控制器qute.四是采用一体化设计，从中心开始，包括以下环状连续工艺单元；进水井和用于回流活性污泥的分水器；分别由四部分组成的选择池和厌氧池。

这之外是有三个曝气器和一个预反硝化的Carrousel 2000系统.五是圆型一体化的设计使得氧化沟不需要额外的管线，即可实现回流污泥在不同工艺单元的分配。

6、结论Carrousel氧化沟由于具有良好的除磷脱氮能力、抗击负荷能力和运营管理方便等优点，已经得到了广泛的应用。

但由于科技的发展和社会的进步，该工艺必将得到进一步的提高。

作者认为：Carrousel氧化沟的未来研究方向主要体现在以下几个方面。

1、结合生物膜法，研究和开发生物模型Carrousel氧化沟。

这样不仅可以提高单位反应器的微生物总量，从而提高有机负荷，而且生物膜本身具有的内置A/O系统强化了脱氮效果。

2、不断提高Carrousel氧化沟中微生物的活性。

例如在氧化沟中投加EM专一菌种、投加铁盐使微生物驯化成生物铁、投加活性炭增强菌胶团的形成并提高耐毒性冲击等。

3、提高Carrousel氧化沟设备性能和检测技术。

提高表曝机、水下推进器的性能，减少维修工作量；利用DO、ORP等多目标监控技术及变频技术是今后Carrousel氧化沟科学运行的必由之路。

4、提高Carrousel氧化沟的耐寒、耐读性能，减少占地面积和工程造价。

膜理论的应用、深池水条件和工艺性能的研究为降低工程造价、提高耐寒耐毒性能等提供了可能的方向。

Oxidize the ditch craft in dirty water handle of application and developmentSummary: This text expatiated primarily the Carrousel oxidizes the construction, craft mechanism of the ditch and circulate the problem exsited in the process with the homologous the method of solution.Finally, introduce the Carrousel oxidize the latest research progress of theditch and pointed out the future and main research direction.Key phrase: The Carrousel oxidizes the ditch divideds by the phosphor takes off the nitrogen construction mechanismApplication and Development of Carrousel Oxidation Ditch Process on Wastewater TreatmentAbstract: The structure and the techniques of carrousel oxidation ditch process on nitrogen and phosphor removal are introduced in this paper. The problems inrunning and their corresponding resolvent are also pointed. At last, The authorshowed the up to date research improvement and the mainly future research dire-ction.Key words: Carrousel; oxidation ditch; nitrogen and phosphor removal; structure;techniques1. ForewordOxidize the ditch( oxidation ditch) again a continuous circulation spirit pond( Continuous loop reactor), is a live and dirty mire method a kind of to transform.Oxidizing the dirty water in ditch handles the craft be researched to manufacture by the hygiene engineering graduate school of Holland in the 50's of 20 centuries success.Since in 1954 at Dutch throw in the usage for the very first time.Because its a water fluid matter good, circulate the stability and manage convenience etc. technique characteristics, already at domestic and international and extensive application in live the dirty water to is dirty to manage aqueously with the industry[1].Current application than oxidize extensively the ditch type include:The ( Pasveer) oxidizes the ditch, the ( Carrousel) oxidizes the ditch, ( Orbal) oxidizes the ditch, the type of T oxidizes the ditch( three ditch types oxidize the ditch), the type of DE oxidizes the ditch to turn to oxidize the ditch with the integral whole.These oxidize the ditch because of the difference of esse in construction with circulating, therefore each characteristics[2].This text will introduce construction, mechanism, existent problem and its latest developments that Carrousel oxidize ditches primarily.2. The Carrousel oxidizes the construction of the ditchThe Carrousel oxidize the ditch to be researched to manufacture by Dutch DHV company development in 1967.Oxidize the last the company of DHV in foundation of the ditch in the original Carrousel to permited specially the company EIMCO to invent again with its patent in the United States Carrousel 2000 system( see the figure ), realizes the living creature of the higher request takes off the nitrogen with divided by the function of .There has been in the world up to now more than 850 Carrousels oxidize the ditch with the Carrousel 2000 system are circulating[3].From diagram therefore, the Carrousel oxidizes the ditch the usage the spirit of that definite direction control with shake up the device, face to mix with the liquid deliver the level speed, from but make drive the liquid of admixture that shake up is in oxidize ditch shut match outlet circulate flow.Therefore oxidize the ditch have the special hydraulics flows the , current complete mix with the characteristics of the type reactor, have the characteristics that push the flow type reactor again, the ditch inside exsits obviously of deliquescence oxygen density steps degree.Oxidizing the ditch cross section is rectangle or trapezoids, the flat surface shape is many for oval, the ditch internal water is deep general for 2.5 ～4.5 ｍ, the breadth is deep compare for 2:1, also have the deep water amount to 7 ms of, ditch inside average speed in water current is 0.3 ms/ s.Oxidize ditch spirit admixture equipments contain surface spirit machine, the spirit of turn to brush or turn the dish and shoot to flow the spirit machine, pipe type spiritmachine with promote take care of type spirit machine etc., match with in recent years usage still contain underwater push machine[4~6].3. The Carrousel oxidizes the mechanism of the ditch3.1 The Carrousel oxidizes the ditch handles dirty and aqueous principleThe at the beginning common Carrousel oxidizes the dirty water in inside in craft of the ditch direct with dirty mire in reflux together enter oxidize the ditch system.The surface spirit machine makes fuse in the liquid of admixture the density of the oxygen DO increases about 2 the 3 mgs/ L.Under this kind of well the term of the oxygen , the microorganism gets the enough deliquescence oxygen comes and go to divided by the BOD;At the same time, the ammonia were too oxidized nitrate with second nitrate, this time, mix with the liquid be placed in the oxygen appearance.In the spirit machine downstream, after water current be become by the swift flow appearance of the spirit District of even flow the appearance, the water current maintains in the minimum current velocity, guaranteeing the live and dirty mire be placed in the floats the appearance.( average current velocity>0.3 ms/ s)Oxidize microbially the process consumed to fuse the oxygen in the water, until the value of DO declines for zero, mixing with the liquid report the anoxia appearance.Versa nitric that turn the function through anoxia area, mix with the liquid enter to have the oxygen area, completing once circulating.That system inside, the BOD declines the solution is a continuous process, the nitric turns the function to turn with the versa nitric the function take place in same pond.Because of structural restrict, this kind of oxidize the ditch although can then valid whereabouts BOD, divided by the phosphorus take off the nitrogenous ability limited[7].For the sake of the acquisition better divided by the phosphorus take off the nitrogenous result, Carrousel 2000 systems increased a oxygen District before common Carrousel oxidize ditch with the unique oxygen area.( call again that the versa nitric in front turns the area)The dirty mire in all refluxes enters the anaerobic District with 10-30% dirty water, can under the anoxia with 10-30% carbon source term complete remaining of dirty mire in reflux inside nitric acid nitrogen to versa nitric to turn, creates for the unique oxygen pond of hereafter unique oxygen term.At the same time, anaerobic District inside of concurrently the sex germs convert the dissolubility BOD VFA, the germ acquire the VFA its assimilation PHB, the energy source needed solves in the phosphoric water and cause phosphatic releasing.The anaerobic District a water enters the inner part installs the unique oxygen area that have the mixer, the so-called unique oxygen is a pond inside to mix with liquid since have no the numerator oxygen, also have no the compound oxygen( nitric acid root), the here unique oxygen environment is next,70-90% dirty water can provide the enough carbon source, can make the germ of released the phosphorus well.The unique oxygen area connects behind the common Carrousel oxidizes the ditch system, further completing to do away with the BOD and take off the nitrogen with divided by the phosphorus .Finally, mix with the liquid transfer the dirty mire inside in oxidize ditch enrich oxygen area eject, while enriching the oxygen environment germ surfeit, phosphorus from the water, ejecting the system with the dirty mire in surplus.Like this, in Carrousel 2000 systems, than completed to do away with the BOD, COD with take off at the same time goodly the nitrogen divided by the phosphorus .Synthesizing and dirty water in the river City , long sand City decontamination center[s of the dirty the factory of water in the first in Kunming of adoption that crafts handles the movement result of the factory therefore:Through Carrousel 2000 system after handling, the BOD,COD, SS does away with the rate to all come to a 90% above, the TN does away with the rate comes to a 80%, the TP does away with the rate to also come to a 90%.3.2 The Carrousel oxidizes the ditch divideds by the phosphorus takes off the nitrogenous influence factor.Affecting the Carrousel oxidizes the ditch divideds by the phosphoric factor is dirty mire , nitrate density and quality densities primarily.The research expresses, being total and dirty mire as 11% that a hour biggest phosphorus 4% with deal is its fuck dirty mire deal within live and dirty mire, keep for the the germ physical endowment measures, but when dirty mire over 15 d hour dirty mire the inside is biggest to contain the obvious descent in deal in phosphorus , canning not reach the biggest divideding by the result of phosphorus on the contrary.Therefore, prolong persistently the dirty mire ( for example 20ds,25ds,30ds) is to have no necessary, proper choose to use within the scope of 8~15 d.At the same time, high nitrate density with low quality density disadvantage in divided by the process of phosphorus .Affecting the Carrousel oxidizes the ditch takes off the nitrogenous and main factor is DO, nitrate density and carbon source densities.The research expresses, oxidizing the ditch inside exsits deliquescence oxygen density steps degree namely the good oxygen area DO attains 3~3.5 mgs/ L, the anoxia area DO attains 0~0.5 mgs/ L is a prior condition to take place nitric turn reaction and versa nitrics turn the reaction.At the same time, ample carbon source and higher C/ the N ratio benefits to take off to complete nitrogenously[7].4. The Carrousel oxidizes problem and solution methods of the ditch esse.Though the Carrousel oxidizes the ditch has a water fluid matter good, the anti- pounds at the burthen ability strong, divided by the phosphorus take off the nitrogen efficiency. But, in physically of movement process, still exsits a series of problem.4.1 Dirty mire inflation problemWhen discard the aquatic carbohydrate more, the N, P contains the unbalance of deal, the pH value is low, oxidizing the dirty mire in inside in ditch carries high, fuse the oxygen density the shortage, line up the mire not etc. causes easily dirty mire in germ in form in silk inflation;Not the dirty mire in germ in form in silk inflation takes place primarily at the waste water water temperature is lower but the dirty mire carries higher hour.The microbial burthen is high, the germs absorbed the large quantity nourishment material, is low because of the temperature, metabolism the speed is slower, accumulating the rises large quantity is high to glue sexual and many sugar materials, making the surface of the live and dirty mire adhere to the water to increase consumedly, SVI the value is very high, becoming the dirty mire inflation.Cause that aim at the dirty mire inflation, can adopt the different counterplan:From the anoxia, water temperature high result in of, can enlargement tolerance or lower into the water measures to alleviate burthen, or the adequacy lowers the MLSS( control dirty mire reflux measure), making need the oxygen measures decrease;If the dirty mire carries high, can increase MLSS, to adjust the burthen, necessity the hour can stop into the water, stuffy a period of time;Can pass the hurl add the nitrogen fertilizer, phosphorus fatty, adjust the admixture nourishment in the liquid material equilibrium( BOD5:N:P=100:5:1);The value of pH over low, can throw to add the lime regulate;Bleach the powder with the liquid chlorin( press to fuck 0.3% of the dirty mire~0.6% the hurl adds), can repress the silk form germ breed, controling the dirty mire in combinative water inflation[11].4.2 Foam problemBecause entering to take the grease of large quantity in the water, handling system can't completely and availably its obviation, parts of greases enriches to gather in in the dirty mire, through turn to brush the oxygen agitation, creation large quantity foam;The mire is partial to long, the dirty mire is aging, and also easy creation foam.Spray to pour the water or divided by with the surface the of do away with the foam, in common use divided by the an organism oil, kerosene, the oil of silicon, throw deal as 0.5~1.5 mgs/ L.Pass to increase dirty mire in pond in spirit in density or adequacies let up the tolerance of , also can control the foam creation effectively.When contain the live material in surface in the waste water more, separate with the foam easily and in advance method or other methods do away with.Also can consider to increase to establish a set of divideding by the oil device moreover.But enhance most importantly the headwaters manage, reducing to contain the oil over the high waste water and other poisonous waste water of into[12].4.3 Float the problem on the dirty mireWhen contain in the waste water the oil measures big, whole system mire quality become light, can't like to control very much in operate process its at two sink the pond stop over time, resulting in the anoxia easily, producing the corrupt and dirty mire ascend to float;When spirit time over long, take place in pond the high degree nitric turn the function, making nitrate density high, at two sink the versa nitric in easy occurrence in pond turn the function, creation nitrogen spirit, make dirty mire ascend float;Moreover, contain the oil in the waste water?Take place the dirty mire ascend after floating should pause enter water, broke off or dirty mire in clearance, judge the clear reason, adjust the operation.The dirty mire sinks to decline the sex bad, can throw to add of oagulate or sloth materials, the improvement precipitates the sex;Such as enter the water carries big let up into the water measures or the enlargement reflux measures;Such as the dirty mire grain small lower the spirit machine turn soon;If discovers versa nitric turning, should let up the tolerance , enlarge the reflux or row the mire measures;If discover the dirty mire is corrupt, should enlargement tolerance, the clearance accumulates the mire, and try the ameliorative pond internal water dint term[12].4.4 Current velocity is not all and the dirty mire sinks to accumulate the problemIn Carrousel oxidize ditch, for acquiring its special admixture with handles result, mix with liquid must with certain current velocity is in ditch circulate flow.Think generally, the lowest current velocity should should attain for an average current velocity for, doing not take place sinking accumulating 0.3~0.5 ms/ s.The spirit equipments that oxidize the ditch is general to turn to brush for the spirit of to turn the dish with the spirit of , turning to brush of immerse to have no depth for 250~300 mms, turn the dish immerse to have no depth for 480~530 mms.With oxidize the ditch water the deep(3.0~3.6 ms) comparing, turn to brush occupied the deep 1/10~ in water 1/12, turned the dish to also occupy the 1/6~ only 1/7, therefore result in to oxidize the ditch upper part current velocity bigger( roughly 0.8~1.2 ms, even larger), but the bottom current velocity is very small( especially at the water is deep 2/3 or 3/4 below, mix with the liquid has no current velocity almost), causing ditch bottom large quantity accumulate the mire( sometimes accumulate the mire thickness amount to a 1.0 ms), the valid capacity that reduced to oxidize the ditch consumedly, lowered to handle result, affected a water fluid matter.Adding the top, downstream leads to flow the plank is a valid method that ameliorative current velocity distribute, increases the oxygen ability with the most convenient measure.The upper stream leads to flow the plank installs at be apart from to turn the 4.0 places( upperstream) ：dish( turn to brush) axis, lead to flow plank high degree as the deep 1/5~ in water 1/6, combine the perpendicularity install in the surface;The downstream leads to flow the plank installs at be apart from to turn dish( turn to brush) axis 3.0 ms.Leading to flow knothole material can use metals or glass steels, but regard glass steel as good.Lead to flow the plank compares with other ameliorative measure, can't not only increase the motive consumes with revolves cost, but also can still than significantly exaltation 充oxygen ability with theories motive efficiency[13].Moreover, pass in the spirit on board swim to establish the underwater push machine can also turn to the spirit of the liquid of admixture that brush the bottom low speed area circulates to flow to rise positive push function, from but the solution oxidizes the problem that low and dirty mire in current velocity in bottom in ditch sink accumulates.Establish the underwater push machine useds for exclusively the push mixs with the liquid can make movement method that oxidize the ditch much more vivid, this for economy energy, lift the high-efficiency having the very important meaning[14].5. The Carrousel oxidizes the development of the ditchBecause the dirty water handles standard inside to divided by the phosphorus take off the nitrogenous request more and more strict, the development that Carrousel further oxidized the ditch to also get.Current, the research and application includes morely below two category type:Tiny bore spirit type Carrousel 2000 systems, Carrousel 3000 system.5.1 Tiny bore spirit type Carrousel 2000 systemTiny bore spirit type Carrousel 2000 tiny bore in adoption in system spirit( provide oxygen equipments as the drum breeze machine), the tiny bore spirit machine can produce the diameter of large quantity as a surface for or so and small spirit steeping, this consumedly increases spirit bubble accumulates, undering the certain circumstance in capacity in pond make the oxygen transfer the gross measures aggrandizement.( if deep increment in pond, its spread the quality efficiency will be higher)Produce the technique ability of the factory house according to the current drum breeze machine, the valid water of the pond is deep biggest amounting to a 8 ms, therefore can select by examinations according to the different craft request the fit water is deep.The tradition oxidizes the ditch pushes to flow is to make use of to turn to brush, turn a disc or pour the umbrella type form machine realizes of, its equipments utilization is low, the motive consumes big.Tiny bore spirit type Carrousel 2000 systems then adopted the underwater pushes the way that flow, rises to dive the propeller the leaf the motivation that round creation the direct function namely in the of water, at push to flow the function to can keep dirty mire from sinking to decline effectively again at the same time.As a result, the adoption dives the propeller since lower the motive consume, making mire water got again to mixs with adequately.Seeing from water power characteristic, tiny bore spirit type Carrousel 2000 systems are wreaths form the fold flows the pond type, concurrently pushing the flow type with complete mix with the type flows .In regard to whole oxidize ditch, can think that oxidize the ditch is a complete mix with spirit pond, its density variety coefficient smallest even can neglect to do not account, enter the water will get the dilution quickly, therefore it have the very strong anti- pounds at the burthen ability.But have oxidize ditch inside of a certain very much the some pushing the characteristic of the flow type, in the nearby district in downstream in machine in spirit inDO density higher, but along with increase with spirit machine distance continuously then the density of DO lowers continuously.( appear the anoxia area)This kind of structure methodmakes friendly oxygen in area in anoxia area exsited to build the thing inside , making use of its water power characteristic well, coming to an efficiently the living creature takes off the nitrogenous purpose.Tiny bore spirit type Carrousel 2000 system though have the oxygen ability strong, divided by the phosphorus take off the nitrogen effective, cover the area little with can consume low etc. advantage, it also exsits at the same time the problem that tiny bore spirit equipments maintain.Current, the service life of the local and tiny bore spirit machine is 5 years in 4~, can amount to 10 years in 8~ goodly, but with import the tiny bore spirit machine compare to still have the certain margin.The spirit machine maintains unlike the form equipments is so convenient, it need to fuck the pond talent fixs, and also is to say once the tiny bore spirit machine appears the problem to need the adoption parallel two inconvenience for or third sets to solving problem, or adopting promoting device waiting to resolving, this too will giving production with managing bringing biggest[15 16].5.2 Carrousel 3000 systemCarrousel 3000 systems are in the Carrousel 2000 systems are ex- to plus a living creature the choice the area.That living creature choice area is a craft to make use of high organism carries to sieve germ grow, repress silk form germ increase, increase each pollutant do away with the rate, afterward principle together Carrousel 2000 system.Carrousel 3000 system of bigger increases to express at:An is to increased the pond deep, can amount to 7.5~8 ms, united at heart circle type, the pond wall uses totally, reducing to cover the area, lowering to build the price to increases to bear the low temperature ability at the same time;( can amount to 7 ℃)Two is the liquid of admixture that spirit equipments that skillful design, the form machine descends to install to lead to flow , the anoxia of take out , adopt the underwater propeller solution current velocity problem;Three is to used the advanced spirit controller QUTE.( it adopt the much aer kind of changing the deal control mode)Four is to adopt the integral whole turn the design, starting from the center, including below wreath form consecution craft unit:Enter the well of water with the cent water machine that used for the live and dirty mire in reflux;Difference from four-part the choice pond that cent constitute with 厌oxygen pond.This outside is a Carrousel to have three spirit machine with a prepare versa nitric turn the pond 2000 system.( such as figure 2 show)Five is tube line that the design that the circular integral whole turn to make oxidize the ditch do not need additionally, can immediately realize dirty mire in reflux allotment in different craft unit[17].6. ConclusionThe Carrousel oxidizes the ditch because of having the good a phosphorus takes off the nitrogen ability, anti- pounds at the burthen ability with circulate to manage the convenience etc. the advantage, having got the extensive application.But because of technological development with social advance, that craft is necessarily will exaltation getting further.The author thinks:The Carrousel oxidizes the future research direction of the ditch will now of main below several aspects.1 Combination living creature method, research with develop the living creature model Carrousel oxidize the ditch.Like this can not only increases the microorganism gross of the unit reactor measures, from but increases the organism carries, but also living creature oneself the inside that have places the A/ the system of O enhances to take off the nitrogen result[18].2 Increases continuously the Carrousel oxidize the microbial activity in inside in ditch.Forexample throw to add the EM in oxidize ditch with single mind the germ grow, throws in that the salt of iron make the microorganism tame the live char in iron, devotion in living creature to become the formation to strengthen the germ gum regiment and increases to bear the toxicity pound at etc..3 Increasing the Carrousel oxidizes the ditch equipments function with supervise and control the technique.Function that increases form machine, underwater propeller, reduce to maintain the workload;Making use of DO, etc. of ORP many targets supervises and control the technique and changes the technique of is from now on the Carrousel oxidizes ditch science circulate necessarily from it road.4 Increasing the Carrousel oxidizes the ditch resistant to cold and bear toxicity can, reduce to cover the area to build the price with the engineering.Theoretical application, deep pond in water power term with the research of the craft function is to lowers the engineering builds the price and increases resistant to cold bear the toxicity can wait to provide the possible direction.。