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Biological Adverse Effects on Bivalves Associated with Trace Metals Under Estuarine EnvironmentsEnrique García-Luque&Angel T.DelValls&Jesus M.Forja&Abelardo Gómez-ParraReceived:4April2006/Accepted:28July2006/Published online:28October2006#Springer Science+Business Media B.V.2006Abstract Toxic effects of pollutants on marine organisms can be studied both by performing field measurements,and by undertaking laboratory simu-lation experiments.Here is described the effect of trace metals Zn,Cd,Pb and Cu on the clam Scrobicularia plana along a salinity gradient simulated in a hypothetical estuary using simulation experiments. The simulator produces a continuous entry of trace metals into the estuary through injection in the lower salinity tank of the system.The clams were exposed during two weeks to different concentration of trace metals to assess the bioaccumulation process along a salinity gradient.Bivalves were analysed for body tissue residue to determine the bioaccumulation factors related to each metal and the salinity influence was addressed.Differences among tanks were observed as a result of the salinity gradient.In the achieved assays, the mechanism of bioaccumulation of Zn and Cd in organisms was more efficient at high salinity values. Bioaccumulation factors for both metals showed a linear increase with the increase of salinity values.It seems that the mechanism of bioaccumulation of Pb and Cu in organisms was dependent on two simulta-neous processes:the proximity to the input point of metals and the low salinity values.Keywords Bioaccumulation.Clams.Estuaries. Metallothioneins.Simulation1IntroductionTrace metals are natural constituents of the marine environment in trace concentrations.However,an-thropogenic inputs have increased strongly the trace metal concentrations in coastal areas during the last century.One of the main access ways of trace metals to the marine environment is through estuaries,which receive human sewage of different origins(Blackstock, 1984).Therefore,in metal-polluted environments,a high availability of a trace metal will promote a high rate of metal entry into the body of any species exposed to this metal.If the rate of uptake exceeds the rate at which the metal can be detoxified or excreted, then the metal is available internally to exert toxic effects(Legras,Mouneyrac,Amiard,Amiard-Triquet, &Rainbow,2000).Toxic effects of pollutants on marine organisms can be studied both by performing field measure-ments,and by undertaking laboratory simulation experiments.Controlled laboratory experiments using an only substance(or a mixture of them)on a single biological species supply very useful information related to the knowledge of pollutant effects.TheEnviron Monit Assess(2007)131:27–35DOI10.1007/s10661-006-9444-xE.García-Luque(*):A.T.DelValls:J.M.Forja:A.Gómez-ParraDepartamento de Química Física,Universidad de Cádiz, Facultad de Ciencias del Mar(CASEM),Campus Río San Pedro s/n,11510Puerto Real,Cádiz,Spaine-mail:enrique.luque@uca.esdevelopment of this kind of bioassays is essential to assess the real impact produced by pollutants.In this study,the adverse effects produced by trace metals on estuarine clams have been characterised using a dynamic simulator of estuaries by conducting different bioassays in which clams were exposed to a dynamic flow of trace metals.The idea of dynamic simulation is basically similar to that described by Bale and Morris(1981).Nevertheless,the dimensions and the features offered by this new simulator are considerably greater(for example,with this system tidal effects also can be simulated).The metals selected for these experiments were Zn, Cd,Pb and Cu.Among benthic species,bivalve molluscs are characterised by being able to accumulate trace metals in concentrations proportional to those present in water or in sediments.Therefore,bivalve molluscs have been used to monitor bioavailability of such contaminants(Pavicic,Skreblin,&Raspor, 1987).The biological species selected in this study was Scrobicularia plana due to its ubiquity,local abundance and importance in the estuarine trophic chain(Ruiz,Bryan,Wigham,&Gibbs,1995).In fact, Scrobicularia plana is an infaunal species commonly inhabiting the intertidal soft bottoms of Northeast Atlantic estuaries,from the Norwegian Sea into the Mediterranean and south to Senegal(Tebble,1966).The general objective of this study is to character-ise the adverse effects produced by trace metals on estuarine clams by means of a dynamic simulator.For this,it has been necessary to quantify the trace metal concentrations in the soft body tissue from specimens of Scrobicularia plana,to calculate the bioaccumula-tion factors for the four trace metals selected and to determine the concentration of metallothioneins in specimens of Scrobicularia plana collected from each tank(as biological response determined).2Materials and Methods2.1Simulator descriptionThe simulator system consists of eight tanks(Plexiglas, cylindrical,and of about10l capacity)interconnected under a hydrodynamic regime(Figure1).The upper tank is supplied with fresh water.The lower tank is supplied with seawater sampled in a clean coastal area. From the lower to the upper tanks,there is a forced flow of water controlled by peristaltic pumps.In the inverse direction,filling the containers in series with fresh water generates a down flow.This permits a constant volume of10l to be maintained in each tank.The flow and temperature control is carried out by a personal computer using specific software devel-oped in Visual Basic and an AID21-bit translation card.The regulation of flow involves setting-up the peristaltic pumps(Masterflex,7521-55)in phase with the flow meters(McMillan Company,111).The temperature is controlled by means of coated dip heaters through thermistor probes.The water mixture is kept homogeneous in each tank by using variable-velocity mechanical stirrers.A more detailed descrip-tion of this system has been previously reported by García-Luque,Forja,DelValls,and Gómez-Parra (2003).After15days,adsorption of metals onto wall tanks can be neglected because this process has a kinetic order of about hours instead of days,reaching stationary state before the first24h.2.2Experimental designThe area of marine influence of a typical estuary was simulated.Specifically,the salinity gradient simulated was comprised between values of10and36,to avoid osmotic impact on the clams.Prior to the beginning of the assay,the clams were purified during10days in an aquarium of70l thanks to a continuos flux of oxygenated water.After this, the specimens of the clam Scrobicularia plana(10per aquarium;average length: 4.4cm;average wet weight:2.5g)were placed in each tank after two weeks of previous acclimatisation period to each salinity value under controlled conditions.Then,a solution with known concentration of the four metals was injected in the lowest salinity tank of the system in a continuous flow by means of a peristaltic pump. (The measured trace metal concentrations in this solution were Zn:Cd:Pb:Cu,5:0.2:1:2mg·l−1,respec-tively).This metal injection was diluted as it reached succeeding tanks.Dilution is result of two processes: the hydrodynamic regime and the inherent reactivity of trace metals along a salinity gradient.The exposure period of the bioassay was15days.After this,clams were collected to assess possible adverse effects (bioaccumulation,metallothionein synthesis)derived of their exposure to trace metals.Parallel to theexperiment,10clams were maintained in a reference aquarium(absence of introduced metals).Along the experiments,some physicochemical parameters(salinity,temperature,pH and dissolved oxygen)were measured in each tank of the simulator to ensure the correct development of the assays.2.3Data calculation and statistical analysisThe results obtained for salinity values,concentration of the four dissolved trace metals,concentration of trace metals bioaccumulated and concentration of metallothioneins were related by means of factor analysis,using principal components(PCA)as the extraction procedure,which is a multivariate statistical technique(MAA)to explore variable distributions.The objective of PCA is to derive a reduced number of new variables as linear combinations of the original varia-bles.This provides a description of the structure of the data with the minimum loss of information.The factor analysis was performed on the correlation matrix,i.e., the variables were auto-scaled(standardised)so as to be treated with equal importance(DelValls&Chapman, 1998).All analyses were performed using the PCA option of the FACTOR procedure,followed by the basic setup for factor analysis procedure(P4M)from the BMDP statistical software package(Frane,Jennrich, &Sampson,1985).The sorted rotated factor loadings are coefficients correlating the original variables and the principal components in this analysis.The variables are reordered so the rotated factor loadings for each factor are grouped together.In this study,we selected to interpret a group of variables as those associated with a particular component where loadings were0.35 or greater,corresponding to an associated explained variance of more than35%.2.4Analytical techniquesPrior to sampling and setting-up the simulations,all equipment,filters,beakers and containers used were thoroughly cleaned with acid(10%HNO3)and then rinsed in reagent grade water(Milli-Q).Figure1Schematic represen-tation of the estuarine hydro-dynamic simulation system (adapted from García-Luque et al.,2003).The salinity was determined by means of an induction salinometer (Beckman RS-10).The total concentration of dissolved trace metals (Zn,Cd,Pb,Cu)was assessed in water samples using a differential pulse anodic stripping voltametry (DPASV),after a digestion procedure with UV radiation (4h)at 85°C (Metrohm,705UV).Measurements were made with static drop mercury electrode (SMDE),using a Metrohm 693processor as reported by Gómez-Parra,Forja,DelValls,Sáenz,and Riba (2000).The analyt-ical procedure for dissolved metals was checked using reference material CASS3with an accuracy of ±90%.All samples were measured at the end of the experiment.Nevertheless,the system had reached stationary state when the injection of the trace metal solution to the system was carried out.Therefore,measured concentrations at the end of the assays are similar than those found during the experiment.To analyse the residue of tissue body for trace metals and to address the bioaccumulation process,organisms were lyophilised and pounded prior to an acidic digestion with nitric acid and hydrogen perox-ide during 1h at 95°C.Samples (previously filtered)were analysed by atomic absorption spectrophotome-try.The concentrations of trace metals Zn and Cu in the samples were determined with a Perkin-Elmer 2100Flame atomic absorption spectrophotometry.The trace metals Cd and Pb were measured by graph-ite furnace atomic absorption spectrophotometry (Perkin-Elmer,4100ZL).The concentration of metallothioneins was ana-lysed on the total body of the organisms at the end of the experiment through Anodic Stripped V oltammetry in the heat stable fraction (the supernatant of the second centrifugation),based on the protocol outlined by Olafson and Olsson (1991).Rabbit liver metal-lothionein (Sigma)was used as reference for the standard addition calibration curve.Total content of protein determination was based on the Bradford method (1976).Metallothionein concentration was expressed in relation to total protein content.3Results and DiscussionFigure 2shows the concentrations of dissolved trace metals along the salinity gradient obtained during the bioassay.In all cases,it can be observed how obtained values are below the theoretical dilution line,showing a non-conservative behaviour for all the metals assessed.Therefore,a high chemical reactivity is shown mainly at low salinity values.The non-conservative behaviour of these metals has been reported for other estuaries (e.g.,Benoit et al.,1994;Windom et al.,1991).Although the behaviour of the assessed metals in the simulation assay is non-conservative,the decreases in concentration in the dissolved phase with salinity show a similar pattern.The trace metalSalinity1620242832[C u ] (p p b )20406080Salinity1620242832[P b ] (p p b )10203040[C d ] (p p b )481216[Z n ] (p p b )4080120160200240Figure 2Concentration of dissolved Zn,Cd,Pb and Cu along the salinity gradient achieved at the bioassay.Dotted line shows the theo-retical dilution line;solid line shows exponential fittings for variations of metal concen-tration with salinity values.concentration gradients versus the salinity increase are described by the following exponential equation:C ¼a þb Áe Àc ÁSð1Þwhere C is the trace metal concentration in the dissolved phase,S is the salinity,and a ,b ,and c are the fitted parameters for each metal.Values for these parameters as well as the correlation coefficients for the equation are shown in Table I .The trace metal concentrations in the soft body tissue from three specimens of Scrobicularia plana collected in each tank of the simulator also was quantified.Figure 3shows the concentrations of bioaccumulated Zn,Cd,Pb and Cu along the salinity gradient in the clams (concentration of metals in biological tissues is expressed taking into consider-ation wet weight of the tissues).In this figure,two different behaviour patterns can be observed.Theconcentrations of Zn and Cd do not show a clear pattern with the salinity increase.On the other hand,the concentrations of Pb and Cu exhibit a decrease with the salinity increase.In fact,bioaccumulation for both metals (Pb and Cu)decreases exponentially with salinity describing an equation similar to expression (1),with correlation coefficients of 0.889for Pb and 0.988for Cu.Bioaccumulation factors (BCFs)for the four trace metals have been calculated also.These factors are calculated as the ratio between the concentration of the bioaccumulated metal and the concentration of the dissolved metal.Obtained results are showed in Figure 4.The bioaccumulation factors for Zn and Cd increase following lightly a linear pattern with the salinity increase.It indicates that the bioaccumulation of Zn and Cd is more effective when salinity increases.Therefore,at high salinity values,the amount of bioaccumulated trace metals (Zn and Cd)is about the same that at low salinity values (Figure 3),although Zn and Cd concentrations in water decrease with the salinity increase (Figure 2).The BCF for Pb does not show a clear trend with the salinity,and varies around an average value (850l kg −1).Therefore,the bioaccumulation of Pb could not depend on salinity values,being controlled by the amount of dissolved Pb along the salinity gradient.Thus,at high salinity values,where dissolved PbTable I Fitted parameters corresponding to Equation (1)(and correlation coefficients)calculated for the trace metal (Zn,Cd,Pb and Cu)concentrations versus salinity values during the bioassayab c r 2Zn 98.23263.7·1050.560.745Cd 4.531539.940.310.739Pb 6.764197.420.290.885Cu20.11743.180.150.932[Z n ] (µ g ·g -1)200300400[C d ] (µ g ·g -1)0.350.400.450.500.55Salinity1620242832[C u ] (µ g ·g -1)020406080Salinity1620242832[P b ] (µ g ·g -1)0102030Figure 3Concentration of Zn,Cd,Pb and Cu bioaccumulated by specimens related to their total weight along the salinity gradient achieved at the bioas-say (metal concentration is expressed taking into consider-ation wet weight of the tissues).concentration is low,it is measured the lowest bio-accumulation for Pb (Figure 3).The variation of BCF for Cu along the salinity gradient is shown in Figure 4.The BCFs are higher at low (16–22)than at high salinity (24–32)values.It could inform that bioaccumulation of Cu is higher at low than at high salinity values.To assess possible adverse effects derived from the exposure of clams to trace metals at different salinity values,the concentration of metallothioneins in speci-mens of Scrobicularia plana collected from each tank has been analysed.Summarised results of metal-lothionein concentrations and total proteins concen-trations in analysed clams are shown in Table II .The metallothionein concentration shows intersite differ-ences that could be associated with the salinity gradient in the simulated estuary.Recent studies (e.g.,Legras et al.,2000;Mouneyrac,Amiard-Triquet,Amiard,&Rainbow,2001)indicate the existence of a relationship between salinity and metallothionein concentration.Salinity gradient in an estuary influen-ces on the chemical speciation of the trace metals and,therefore,on its bioavailability.The results obtained for salinity values,concentra-tion of the four dissolved trace metals,concentration of trace metals bioaccumulated and concentration of metallothioneins were linked by means of a MAA.The application of PCA to the chemical data represents the original variables by four new variables,or principal factors (Table III ).These factors explain 94.5%of the variance in the original data set.The loadings following varimax rotation for the four factors are given in Table III .Each factor is described according to the dominant group of variables.Table II Concentration of metallothioneins (MTs,μg)normalised to the total content of proteins (Tot.prot.,mg)measured in the soft body of individuals of the clam Scrobicularia plana collected from each tank in the simulatorTank 1Tank 2Tank 3Tank 4Tank 5Tank 6Tank 7Tank 8MTs/Tot.prot.(μg mg −1)Specimen A 70.4347.2730.9733.4845.1374.5199.3378.92Specimen B 45.8048.8649.4237.2965.5668.69111.9067.21St.dev.17.42 1.1313.05 2.6914.45 4.128.898.27Total proteins (mg ml −1)Specimen A 1.63 2.48 2.33 2.22 4.69 1.62 2.60 1.06Specimen B1.342.11 1.41 1.96 1.63 2.19 1.22 1.42St.dev.0.200.260.650.192.160.410.980.26Standard deviation values are also expressed.B C F Z n (l ·k g -1)10002000300040005000B C F C d (l ·k g -1)4080120Salinity1620242832B C F P b (l ·k g -1)40080012001600Salinity1620242832B C F C u (l ·k g -1)2004006008001000Figure 4Bioaccumulation fac-tors (BCFs)calculated for Zn,Cd,Pb and Cu along the salin-ity gradient achieved at the bioassay.The first principal factor,#1is predominant and accounts for 70.41%of the total variance;this factor could be called ‘Influence of salinity on concentration of dissolved and bioaccumulated trace metals.’This component shows positive loadings on the concentra-tion of dissolved Zn,Cd,Pb and Cu,and the concentration of bioaccumulated Pb and Cu.A negative loading has been founded for the salinity.Clearly,this component relates inversely the concen-tration of the four dissolved trace metals and the concentration of bioaccumulated Pb and Cu with salinity.Therefore,at high salinity values,low concentrations of dissolved trace metals and low concentrations of bioaccumulated Pb and Cu are quantified.Besides,it confirms that the values of bioaccumu-lated Pb and Cu are related to the concentrations of dissolved Pb and Cu in a direct way.Amiard,Amiard-Triquet,Berthet,and Metayer (1987)described a similar behaviour for both metals.They indicated that field and laboratory studies conducted using individ-uals of the clam Scrobicularia plana and another species show that the bioaccumulated trace metals depend mainly on environmental levels of these metals.On the other hand,the bioaccumulation of Zn and Cd is not associated with this factor,so could be prevailing at high salinity values as has been discussed previously for the BCF of these two metals.The second factor,#2accounts for the 13.41%of the total variance and could be called “Influence of the physicochemical variable ‘salinity ’on metal-lothionein synthesis.”This component shows nega-tive loadings on the salinity and the concentration of metallothioneins.This component relates lightly these two variables.It could indicate that,under theconditions of this bioassay,a physicochemical vari-able (salinity)shows higher influence in the induction of metallothioneins than the concentration of trace metals (dissolved or bioaccumulated).The third factor,#3accounts for the 7.12%of the total variance (a low loading of the total value)and could be called ‘Bioaccumulation of Cd in soft body tissue clam.’This factor shows only positive loading on the concentration of bioaccumulated Cd.It could inform that the influence of the different variables was not addressed under the conditions of this bioassay,so other processes should be affecting the bioaccumula-tion of this metal.The fourth factor,#4,could be called ‘Bioaccumu-lation of Zn in soft body tissue clam.’It is the only factor in which the concentration of Zn in clams is2Factor 1Factor 22-2-2Tank 1Tank 5Tank 7Tank 6Tank 3Tank 4Tank 2Tank 8(13.41%)(70.41%)Figure 5Distribution of the different cases (represented by the tanks of the simulator)in the space defined by factors 1and 2(F1:70.41%of the total variance and F2:13.41%of the total variance).Variable Factor 1(70.41%)Factor 2(13.41%)Factor 3(7.12%)Factor 4(3.56%)t3.1Salinity −0.8248−0.4823––t3.2Diss.[Zn]0.8069––0.4216t3.3Diss.[Cd]0.7973––0.4294t3.4Diss.[Pb]0.8422––0.3810t3.5Diss.[Cu]0.8351–––t3.6Bioacc.[Zn]–––0.9142t3.7Bioacc.[Cd]––0.9397–t3.8Bioacc.[Pb]0.8698–––t3.9Bioacc.[Cu]0.7348––0.6160t3.10[MTs]–−0.9491––t3.11Table III Sorted rotated factor loading (pattern)of 10variables on the bioassay The loading matrix has been rearranged so that the col-umns appear in decreasing order of variance (in brack-ets)explained by factors.Only loading greater than 0.35is shown in table.Factors are numbered con-secutively from left to right in order of decreasing vari-ance explained.included,but with the lowest variance explained (3.56%).So,its description should be taken with caution.Figure5shows the ordination of the cases (represented by the tanks of the simulator)in the space defined by factors1and2(83.8%of the total variance,as a whole).Tanks1and8represent two extreme situations.Tank1shows the highest score for Factor1,so the highest dissolved concentrations for the four metals and the highest concentrations of Pb and Cu in clams can be found at salinity value of Tank1(18).Tank8represents the opposite situation: dissolved concentrations for the four metals and concentrations of Pb and Cu in clams show the lowest values.The rest of the tanks show intermediate situations.This behaviour is related to the distance of each tank to the input point of metals into the system. On the other hand,Tanks5,6and7show a relatively significant induction of metallothioneins,being Tank 7where this process is specially marked(This Tank shows the highest score for Factor2).The other two factors(3and4)are not shown in Figure5owing to the low proportion of the total variance explained by them.4ConclusionsIn this study,adverse effects provoked by trace metals on estuarine clams have been characterised using a dynamic simulator.The bioaccumulation factors related to each metal and the salinity influence were addressed.Under conditions employed in these bio-assays,it could be inferred that:(1)The mechanism of bioaccumulation for Zn andCd in clams was more efficient at high salinity values.Therefore,bioaccumulation factors for both metals showed a linear increase with the increase of salinity values.(2)It seems that the mechanism of bioaccumulationfor Pb and Cu in bivalves was dependent on two simultaneous processes:a)the proximity to the input point of trace metals employed and b)the low salinity values.(3)The process of induction of metallothioneins inthis experiment is more related to existing salinity values than concentration of the metals employed.Acknowledgments This research was supported by projects with Spanish Ministries:‘Ministerio de Ciencia y Tecnología’(REN2002-01699)and‘Ministerio de Fomento’(PATRIM/PR/ 2002-139).ReferencesAmiard,J.C.,Amiard-Triquet,C.,Berthet,B.,&Metayer,C.(1987).Comparative study of the patterns of bioaccumu-lation of essential(Cu,Zn)and non-essential(Cd,Pb) trace metals in various estuarine and coastal organisms.Journal of Experimental Marine Biology and Ecology, 106,73–89.Bale,A.J.,&Morris,A.W.(1981).Laboratory simulation of chemical processes induced by estuarine mixing:The behaviour of iron and phosphate in estuaries.Estuarine, Coastal and Shelf Science,13,1–10.Benoit,G.,Otkay-Marshall, A.,Cantu, A.,Hood, E.M., Coleman, C.H.,Corapcioglu,M.O.,et al.(1994).Partitioning of Cu,Pb,Ag,Zn,Fe,Al and Mn between filter-retained particles,colloids,and solution in six Texas estuaries.Marine Chemistry,45,307–336. Blackstock,K.J.(1984).Biochemical metabolic regulatory responses of marine invertebrates to natural environmental change and marine pollution.Oceanography and Marine Biology:Annual review,22,263–313.Bradford,M.M.(1976).A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding.Analytical Biochemistry, 72,248–254.DelValls,T.A.,&Chapman,P.M.(1998).Site-specific sediment quality values for the Gulf of Cádiz(Spain)and San Francisco Bay(USA),using the sediment quality triad and multivariate analysis.Ciencias Marinas,24,313–336. Frane,J.,Jennrich R.,&Sampson,P.(1985).Factor analysis.In:W.J.Dixon(Ed.),BMDP statistical software(pp.480–500).Berkeley:University of California.García-Luque,E.,Forja,J.M.,DelValls,T.A.,&Gómez-Parra,A.(2003).The behaviour of heavy metals from theGuadalquivir estuary after the Aznalcóllar mining spill: Field and laboratory surveys.Environmental Monitoring and Assessment,83,71–88.Gómez-Parra,A.,Forja,J.M.,DelValls,T.A.,Sáenz,I.,& Riba,I.(2000).Early contamination by heavy metals of the Guadalquivir Estuary after the Aznalcóllar mining spill (SW Spain).Marine Pollution Bulletin,40,1115–1123. Legras,S.,Mouneyrac,C.,Amiard,J.C.,Amiard-Triquet,C., &Rainbow,P.S.(2000).Changes in metallothionein concentrations in response to variation in natural factors (salinity,sex,weight)and metal contamination in crabs from a metal-rich estuary.Journal of Experimental Marine Biology and Ecology,246,259–279.Mouneyrac,C.,Amiard-Triquet,C.,Amiard,J.C.,&Rainbow, P.S.(2001).Comparison of metallothionein concentra-tions and tissue distribution of trace metals in crabs (Pachygrapsus marmoratus)from a metal-rich estuary,in and out of the reproductive parative Bio-chemistry and Physiology.Part C,129,193–209.Olafson,R.W.,&Olsson,P. E.(1991).Electrochemical detection of metallothionein.Methods in Enzymology, 205,205–213Pavicic,J.,Skreblin,M.,&Raspor,B.(1987).Metal pollution assessmet of the marine environment by determination of metal-binding proteins in Mytillus sp.Marine Chemistry, 22,235–248.Ruiz,J.M.,Bryan,G.W.,Wigham,G.D.,&Gibbs,P.E.(1995).Effects of tributyltin(TBT)exposure on thereproduction and embryonic development of the bivalve Scrobicularia plana.Marine Environmental Research,40, 363–379.Tebble,N.(1966)British bivalve seashells(p.212).London: British Museum Natural History.Windom,H.,Byrd,J.,Smith,R.,Hungspreugs,M.,Dharm-vanij,S.,Thumtrakul,W.,et al.(1991).Trace metal–nutrient relationships in estuaries.Marine Chemistry,32, 177–194.。

环境科学与工程英文文献

环境科学与工程英文文献Environmental Science and EngineeringEnvironmental science and engineering is an interdisciplinary field that combines knowledge from various scientific disciplines to understand and address environmental issues. It encompasses the study of the natural environment, the built environment, and the interactions between them.One key aspect of environmental science and engineering is the study of air pollution. Air pollution refers to the presence of harmful substances in the air, which can have detrimental effects on human health and the environment. Research in this area focuses on identifying sources of air pollution, measuring air quality, and developing strategies to mitigate pollution. For example, studies may investigate the impact of industrial emissions on air quality in urban areas and propose technologies to reduce pollutant emissions.Water pollution is another important concern for environmental scientists and engineers. Water pollution occurs when harmful substances contaminate water bodies, making it unsafe for use or threatening the survival of aquatic organisms. Research in this area may involve studying the effects of agricultural runoff on water quality or developing technologies for wastewater treatment. Additionally, researchers may explore the impacts of climate change on water availability and quality.Environmental scientists and engineers are also involved in the field of waste management. This includes the study of wastegeneration, collection, and disposal methods. Researchers may investigate the environmental impact of different waste management practices and evaluate the efficacy of recycling and waste reduction programs. Innovative approaches, such as waste-to-energy technologies, may be explored to minimize the environmental impact of waste disposal.Another area of focus in environmental science and engineering is the study of renewable energy sources. With the increasing demand for energy and the need to reduce greenhouse gas emissions, researchers are exploring alternative energy options. This may involve studying the efficiency and environmental impacts of solar, wind, and biomass energy systems. Additionally, researchers may investigate the feasibility of energy storage technologies to ensure a reliable and sustainable energy supply. Overall, environmental science and engineering play a crucial role in understanding and addressing environmental challenges. By combining scientific knowledge and engineering principles, researchers aim to protect and preserve the natural environment for current and future generations. The application of innovative technologies and the development of sustainable practices are essential for promoting a clean and healthy environment.。

(完整版)(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。

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。

环境工程英语翻译原文

Evaluation of the eﬀect of small organic acids on phytoextraction of Cu and Pb from soilwith tobacco Nicotiana tabacumMichael W.H.Evangelou *,Mathias Ebel,Andreas SchaeﬀerInstitut fu ¨r Biologie V,RWTH Aachen,Worringerweg 1,52056Aachen,Germany Received 1February 2005;received in revised form 23August 2005;accepted 24August 2005Available online 6December 2005AbstractPhytoremediation,the use of plants to extract contaminants from soils and groundwater,is a promising approach for cleaning up soils contaminated with heavy metals.However its use is limited by the time required for plant growth,the nutrient supply and,moreover,by the limited metal uptake capacity.Synthetic chelators have shown positive eﬀects in enhancing heavy metal extraction,but they have also revealed several negative side-eﬀects.The objective of this study was to investigate the use of three natural low molecular weight organic acids (NLMWOA)(citric,oxalic,and tartaric acid)as an alternative to synthetic chelators.Slurry-,column-,toxicity-and phytoextraction experiments were per-formed.For the phytoextraction experiment the three NLMWOA were applied to a copper-and a lead-contaminated soil respectively.A signiﬁcant increase in copper uptake was visible only in the citric acid treatment (67mg kg À1)in comparison to the EDTA treatment (42mg kg À1).The NLMWOA application showed no enhanced eﬀect concerning the lead phytoextraction.A possible explanation for this lack of signiﬁcance could be the rate of the degradation of NLMWOA.This rate might well be too high for these heavy metals with low mobility and bioavailability such as lead.The amounts of NLMWOA applied to the soil were very high (62.5mmol kg À1of soil)and the eﬀect was too little.In this respect EDTA,which was applied in very small amounts (0.125mmol kg À1)was more eﬃcient.Thus making NLMWOA unsuitable to enhance phytoextraction of heavy metals from soil.Ó2005Elsevier Ltd.All rights reserved.Keywords:Phytoremediation;Heavy metals;Organic acids;Chelate assisted;Tobacco1.IntroductionPhytoremediation is deﬁned as the use of green plants in removing pollutants from the environment,or render-ing them harmless (Raskin et al.,1997).Phytoremedia-tion can be used to remove organic as well as inorganic pollutants.As compared to other remediation technologies,such as land ﬁlling,ﬁxation and leaching,it is cost-eﬀective,and as it does not adversely alter the soil matrix;it causes only minimal environmental distur-bance.The sites are usually aesthetically pleasing and therefore more readily accepted by the public.The Ger-man phytoremediation sites in Leipzig has for instance,been well received by the inhabitants of the immediate vicinity.0045-6535/$-see front matter Ó2005Elsevier Ltd.All rights reserved.doi:10.1016/j.chemosphere.2005.08.042*Corresponding author.Tel.:+492418026686;fax:+492418022182.E-mail address:evangelou@bio5.rwth-aachen.de (M.W.H.Evangelou).Chemosphere 63(2006)996–1004/locate/chemosphereAlthough all plants have the potential to extract met-als from soil,some plants have shown the ability to extract,accumulate and tolerate high levels of heavy metals.Such plants are termed hyperaccumulators, which are taxonomically widespread throughout the plant kingdom.Metal hyperaccumulation is an ecophys-iological adaptation to metalliferous soils(Maywald and Weigel,1997).The potential for application of hyperac-cumulators in bioremediation is limited by the fact that they are slow growing and have a small biomass.These characteristics are contrary to the ones proposed by Robinson et al.(2000)who suggested that a plant used for phytoremediation should be fast growing,deep-rooted,easily propagated and accumulating the target metal.According to Ro¨mkens et al.(2002)it should also have a high biomass production.For these reasons the tobacco plant,Nicotiana tabacum is suitable for phyto-remediation,in the areas of Latin and South America.Chelators have shown an ability to enhance phyto-remediation of heavy metals from contaminated soil, an ability that could balance the characteristics of the hyperaccumulating plants.Although synthetic chelators, such as EDTA,have shown positive eﬀects on the enhancement of phytoextraction of metals from soil, their use has disadvantages:EDTA is non-selective in extracting metals(Barona et al.,2001)and has poor bio-degradability(Wasay et al.,1998).It has also the eﬀect of decreasing the plant growth severely(Chen and Cut-right,2001)even at very low concentrations.An alterna-tive to synthetic chelators could be found in naturally occurring chelating agents,the so called biochelators. Biochelators,such as humic acids,have already been shown to have positive eﬀects on the phytoextraction of heavy metals from soil(Evangelou et al.,2004). Another possible alternative is natural low molecular weight organic acids(NLMWOA),which are exudated by plants into the soil.It is known that exudation of organic compounds by roots may inﬂuence the solubility of essential and toxic ions indirectly and directly;indirectly,through their eﬀects on microbial activity,rhizosphere physical prop-erties and root growth dynamics and,directly,through acidiﬁcation,chelation,precipitation and oxidation–reduction reactions in the rhizosphere(Uren and Reisenauer,1988;Marschner et al.,1995).Of these com-pounds,NLMWOA are of particular importance due to their complexing properties,which play a signiﬁcant role in heavy metal solubility(Mench and Martin,1991; Krishnamurti et al.,1997;Nigam et al.,2000)and the mobilization of mineral nutrients(Zhang et al.,1989; Jones et al.,1996),even more important than the pH of the soil(Huang et al.,1998).The objective of this research was to investigate the ability of NLMWOA in enhancing the phytoextraction of copper and lead from soil by the use of tobacco plants under laboratory conditions.The potential of NLMWOA in replacing compounds such as EDTA or other synthetic chelators as enhancing agents for the phytoremediation of heavy metal contaminated soils was assessed.2.Materials and methods2.1.Soil characterizationA silty–loamy sand agricultural soil,USDA(Soil Survey Manual,1995),was collected from0to30cm surface layer of the Melatenﬁeld in Aachen,Germany. The soil was air-dried at room temperature,sieved through a2-mm sieve and characterised as follows. The sand,clay and silt fractions of the samples were determined by the hydrometer methods(Bouyoucous, 1952).Organic matter content was determined by the Walkley–Black method(Nelson and Sommers,1996). The pH was measured by the CaCl2-method(Lewan-dowski et al.,1997).The initial total copper and lead content of the soil,as determined by the aqua regia method after DIN38414Teil7,Copper and lead analy-sis in theﬁltrate was performed byﬂame AAS(Perkin–Elmer1100B).Standards for the AAS calibration were prepared in the extraction solution by the addition of appropriate quantities of copper and lead respectively. The soil properties are listed in Table1.2.2.Pot experiments2.2.1.Soil preparationThe pot experiments were conducted in a greenhouse from March to April.Four-hundred grams of air-dried and sieved soil wasﬁlled in0.5l plastic pots with six small holes at the bottom.The plastic pots were pre-washed with dilute nitric acid to eliminate any adsorbed metals.A pot-plate was placed under each pot.To each pot the following amounts of fertilizer were applied: 674.4mg Ca(NO3)2Æ4H2O,175.6mg KH2PO4,resulting in a concentration of200and100mg kgÀ1respectively. Table1Selected properties and heavy metals concentrations of the used soilParameters ContentpH 6.8Organic matter(%) 3.5Soil fractionsSand(%)49.4Clay(%)42.1Silt(%)8.5Copper(mg kgÀ1)21.8Lead(mg kgÀ1)48.7M.W.H.Evangelou et al./Chemosphere63(2006)996–10049972.2.2.Seedling preparation and plant growthTobacco plants(N.tabacum SR-1)were used for the pot experiments.This selection was based on the plantÕs ability to produce a relative great biomass in a very short time.Seeds of tobacco plants were germinated in a peat/ sand mixture.After3weeks,seedlings with similar bio-mass were used for the pot experiments.All tobacco plants were grown under controlled envi-ronmental conditions with a16h light period(light intensity of320l mol mÀ2sÀ1),a25/20°C light/dark temperature regime,and60%relative humidity(Walch-Liu et al.,2000).2.2.3.Toxicity pot experimentThe experiment included the control treatment(no additional chelating agents),and treatments with62.5, 125,and250mmol kgÀ1for the NLMWOA and0.125, 0.25,0.25,62.5,125,and250mmol kgÀ1for EDTA.On the day of the chelating agentsÕapplication,seedlings with similar biomass were transferred into the pots containing the metal and NLMWOA spiked soil.One seedling was planted into each pot,thereafter,the experiment was ini-tiated.The experiment was performed in triplicates.The toxicity eﬀects were observed with the aid of the dry mass.2.2.4.Phytoextraction pot experimentsThe experiments included the control treatments(no additional heavy metals),and treatments with225and 450mg kgÀ1copper applied as CuCl2and300and 600mg kgÀ1lead applied as Pb(NO3)2.Each treat-ment was performed in triplicates.One day after the application of copper or lead,the fertilizers,and 62.5mmol kgÀ1NLMWOA(citric,oxalic,and tartaric acid)or0.125mmol kgÀ1EDTA were applied and sub-sequently one seedling was placed on each pot,thereaf-ter the experiment was initiated.All seedlings used had similar biomass.In order to avoid the leaching of copper and lead from the soil the distilled water,which was used for watering the plants was never added directly to the soil surface,but into the pot-plate.2.2.5.Plant harvest and analysisPlants used in the pot experiments were harvested after approximately3weeks of growth.During harvest, plants were cut short above ground,and separated into stem and leaves.The subsequent steps were performed according to Jones and Case(1990).Plant samples(stem and leaves)were rinsed brieﬂy in deionised water,dried between Kleenex tissues to remove surface contamina-tion,and oven dried at70°C to a constant weight. The dry weight was determined and the samples were homogenised in particle size by grounding in a ball mill.After milling,200±5mg of dried plant tissue were weighed into a15ml high form porcelain crucible.The plant tissue was ashed at500°C for5h in a muﬄe fur-nace and cooled down.At60°C,2ml of15%HCl were added and evaporated.At room temperature,2ml of 15%HCl were again added.The ash was suspended with the assistance of a glass stick,and the suspension subse-quentlyﬁltered through a quantitativeﬁlter paper(595, Schleicher and Schuell Filters,pore size4l m).Theﬁl-trate was adjusted to20ml with deionised water and analysed for copper and lead by AAS.2.3.Slurry experimentOne gram of the agricultural soil was weighed into a 50ml polypropylene copolymer centrifuge tube.The centrifuge tubes were pre-washed with dilute nitric acid to eliminate any adsorbed metals.The soil was suspended with15ml of a62.5mM solution containing, either,citric acid,oxalic acid,tartaric acid or0.125mM EDTA.Each suspension was performed at three diﬀer-ent pH values,9,7,and5adjusted with1M NaOH. The tubes were shaken for18h at70rpm,and subse-quently the tubes were centrifuged at14.000g for 10min.Each sample was thenﬁltered through a quanti-tativeﬁlter paper(595,Schleicher and Schuell Filters, pore size4l m).In order to conserve the samples 100l l of65%HNO3was added to each of them.The copper and lead content in the solution was performed by AAS.Each treatment was performed in triplicates.2.4.Column experimentGlass columns(24mm inner diameter and140mm in length)were used in this study.The columns were pre-washed with dilute nitric acid to eliminate any adsorbed metals.Spiked soil,25g containing450mg kgÀ1of cop-per applied as CuCl2and600mg kgÀ1of lead applied as Pb(NO3)2,was packed into the column.The soil was spiked3months before the column experiment,and it was achieved by the application of large volumes of dis-solved CuCl2and Pb(NO3)2at low concentrations in order to achieve an equal distribution.The pore volume of the column,which was determined after DIN19683-13was56%,which equals14ml.The solution was ponded,about6cm above the soil surface,on the column and maintained during the leaching.The eﬄuentﬂow rate was kept at an average of1pore volume hÀ1 (14±1ml hÀ1).Each column was eluted with60–100ml of62.5mM citric acid,oxalic acid,tartaric acid, 0.125mM EDTA,or10mM CaCl2solution respectively. The solution level varied slightly according to leachate ﬂow.At the bottom of the columns,the leachates were collected in14ml aliquots and measured at the same day.To avoid pH dependent eﬀects chelating agentsÕsolu-tions were adjusted to a pH value of6.8with1M NaOH, which is the soilÕs pH value.The solution of10mM CaCl2 has comparable ionic strength to the natural soil solutions (Shuman,1990).CaCl2serves as a control and to give hints for the later phytoextraction experiment.Each solu-998M.W.H.Evangelou et al./Chemosphere63(2006)996–1004tion-column experiment was performed inﬁve replicates. The copper and lead content was determined by AAS.2.5.Statistical analysisEach copper and lead concentration and each chelat-ing agent concentration was performed in triplicates (n=3)except for the column experiment,which was performed inﬁve parallels(n=5).The diﬀerence between speciﬁc pairs of means was identiﬁed by t-test (P<0.05).Statistical analysis of the data was performed by using Excel XP(Microsoft).3.Results3.1.Toxicity pot experimentDry matter yields of the shoots(sum of leaves and stem)are shown in Fig.1.The application of NLMWOA to the soil did not adversely aﬀect dry matter production of the plants at a concentration of62.5mmol kgÀ1,but toxicity symptoms such as lower dry weight and chlorosis were visible for higher concentrations of these chelating agents.Citric acid showed already signiﬁcant(P<0.05) toxicity eﬀects at a concentration of125mmol kgÀ1.Tar-taric acid and oxalic acid showed only slight toxicity at this concentration.EDTA did not show any adverse eﬀects at a concentration of<0.125mmol kgÀ1.At 1.25mmol kgÀ1of EDTA(Fig.1b)the leaves showed necrotic lesions and the dry weight was negligible.At a concentration of0.25mmol kgÀ1EDTA the dry weight is only slightly lower but the standard deviation is higher in comparison to the0.125mmol kgÀ1application.3.2.Phytoextraction pot experimentFig.2shows that copper and lead concentrations in the shoots,increased with increasing copper and lead concentrations in the soil.The uptake of copper in the shoots was particularly enhanced with citric acid.The treatment with62.5mmol kgÀ1citric acid caused a sig-niﬁcantly(P<0.05)higher concentration of copper in the shoots as compared to the control,and the other NLMWOA and EDTA applications.In the case of citric acid application copper concentrations in the shoots reached67mg kgÀ1.The eﬀect of oxalic and EDTA additions on copper plant uptake was less prominent, but nevertheless showed an increase in comparison to both the control and tartaric acid.Tartaric acid addition on copper plant uptake showed no enhancing eﬀect.In the case of lead only EDTA showed an enhancing eﬀect, and the shoots contained approximately63mg kgÀ1of lead.The application of the NLMWOA had no signiﬁ-cant(P<0.05)eﬀect,and the uptake of lead averaged to the same order of magnitude as the control.3.3.pH changeThe pH-values at the beginning and at the end of the phytoextraction experiments are shown in Table2.At the beginning of the experiment the pH value of the con-trol soil was0.3lower than its native pH,probably through the application of fertilizers.The application of copper and lead further decreased the pH.At the end of the experiment the control soil reached its native pH.In the case of EDTA,the pH changes were similar as in the case of control.The application of NLMWOA lowered the pH to an average value of5.6at the begin-ning of the experiment.At the end of the experiment the pH reached values in average around7.7,which is0.9 higher than the native pH of the soil.3.4.Slurry experimentFig.1shows the copper and lead mobilisation in percentage,of the natural contaminated soil,whichM.W.H.Evangelou et al./Chemosphere63(2006)996–1004999contained 21.8and 48.7mg kg À1copper and lead respectively.The mobilised copper by the NLMWOA was signiﬁcantly (P <0.05)higher in comparison to that of EDTA.The amounts mobilised by the diﬀerent NLMWOA were in the same order of magnitude.The NLMWOA mobilised approximately 20–25%of copper (Fig.3a)and approximately 8%of lead (Fig.3b)refer-ring to the initial concentrations.Whilst the diﬀerence between the NLMWOA and EDTA in the mobilisation capability of copper was very high,mobilisation of lead amounts was of the same order of magnitude.Only citric acid at pH 5stands out with a lead mobilisation of approximately 36%.The amounts mobilised by milli-pore water (control)approximately 1%copper and 0.5%lead have been subtracted.3.5.Column experimentFig.4depicts copper and lead mobilised from a soil spiked with 450copper and 600mg kg À1lead respec-tively,through a column experiment,in percentage of the total amount of copper and lead in the soil.The cop-per mobilised by NLMWOA was to a signiﬁcant (P <0.05)extent higher than by EDTA.EDTA mobi-lised approximately 0.4%more than CaCl 2but both average out at the same order of magnitude.In compar-ison to the NLMWOA,the control with CaCl 2and EDTA mobilised negligible amounts of copper.Citric acid mobilised the most in the ﬁrst fraction,approxi-mately 25%.The mobilised amounts declined with the number of pore volumes.Oxalic and tartaric acid reached their maximum at the fourth pore volume,but mobilised only approximately 9%and 3%respectively.Table 2The soil pH before and after the growth of tobacco plants for 3weeks in soil spiked with copper (panel A)and lead (panel B)and treated with NLMWOA and EDTA Application Control Cu 225Cu 450pH start pH end pH start pH end pH start pH end Panel A Control 6.46±0.09 6.79±0.08 6.23±0.02 6.67±0.02 6.18±0.01 6.64±0.14Citric acid 5.65±0.077.45±0.06 5.54±0.047.44±0.08 5.48±0.117.45±0.04Oxalic acid 5.66±0.057.64±0.06 5.42±0.017.73±0.11 5.42±0.017.73±0.11Tartaric acid 5.72±0.037.45±0.10 5.62±0.037.71±0.01 5.53±0.037.76±0.09Na 2EDTA6.40±0.09 6.83±0.106.36±0.03 6.67±0.036.36±0.03 6.67±0.03Control Pb 300Pb 600pH startpH end pH start pH end pH start pH end Panel B Control 6.46±0.09 6.79±0.08 6.41±0.03 6.73±0.03 6.19±0.01 6.91±0.07Citric acid 5.65±0.077.45±0.06 5.48±0.037.41±0.00 5.34±0.04 6.91±0.07Oxalic acid 5.66±0.057.64±0.06 5.55±0.087.59±0.08 5.54±0.017.68±0.12Tartaric acid 5.72±0.037.45±0.10 5.65±0.047.80±0.07 5.65±0.047.71±0.10Na 2EDTA6.40±0.096.83±0.10 6.38±0.146.90±0.01 6.40±0.016.78±0.151000M.W.H.Evangelou et al./Chemosphere 63(2006)996–1004The lead mobilised by NLMWOA,EDTA,and CaCl 2ranged at the same order or magnitude,between 0.5%and 2%.In comparison to oxalic and tartaric acid,citric acid showed a diﬀerent extraction curve in the extraction of lead and copper.In the extraction of lead the curve reached its maximum in the second pore volume.4.DiscussionThe phytotoxicity experiments depicted a great diﬀer-ence between NLMWOA and EDTA concerning their toxicity to plants.EDTA showed a very high toxicity (Fig.1b),as reported by Chen and Cutright (2001),and revealed a decreased plant growth at the concentra-tion of 1.25mmol kg À1in soil.At EDTA concentration of 0.125mmol kg À1in soil the plants showed no toxicity symptoms and had a very small variation among the triplicates.At 0.25mmol kg À1,the dry weight is similar to that of the control,but the standard deviation is very high,so that a lower concentration was chosen for the phytoextraction experiments (Fig.1b).The NLMWOAapplication of 62.5mmol kg À1showed no adverse eﬀects on the dry matter production of the shoots,and even a slight increase in shoots yield is visible (Fig.1a),as a consequence this concentration was chosen for the phytoextraction experiment.Higher concentrations of NLWOA resulted in biomass decrease,probably due to the destruction of the physiological barrier by NLMWOA in roots which controls the uptake of solutes (Vassil et al.,1998).NLWOA may damage the plasma membranes which are normally stabilised by Ca 2+and Zn 2+ions (Pasternak,1987;Kaszuba and Hunt,1990)and may confer random metal complexes of soil–solu-tion access to root xylem and to the shoot via the tran-spiration stream (Vassil et al.,1998).Prior to the organic acid toxicity tests,copper and lead toxicity experiments were performed.These showed no apparent harmful eﬀects of copper or lead on the plants for a soil copper content of 450mg kg À1and a soil lead content of 600mg kg À1(data not shown).The analysis of plant material indicated that citric acid (62.5mmol kg À1)and EDTA (0.125mmol kg À1)M.W.H.Evangelou et al./Chemosphere 63(2006)996–10041001treated soil signiﬁcantly(P<0.05)increased the concen-trations of copper in the shoots by2.3and1.1-fold respectively in comparison to the control plants (Fig.2).The increase by the addition of EDTA and NLMWOA was not as high as stated by Schmidt (2003)and Gramss et al.(2004)respectively.Although tartaric acid showed mobilisation potential equal to that of citric acid,at all pH values,(Fig.3)it did not increase the copper concentrations in the shoots(Fig.2).Oxalic acid increased the copper concentration in the shoots in the same order of magnitude as EDTA.The plant analysis,revealed that the NLMWOA had no enhancing eﬀect in the uptake of lead into the plants,although NLMWOA treatments showed higher mobilisation capabilities in slurry(Fig.3b)and column experiments (Fig.4b)than EDTA.EDTA showed an approximately 3-fold increase of lead concentration in the shoots (Fig.2),which is still lower from that stated by Grcman et al.(2001).Regarding that the concentration of NLMWOA in the soil used in the phytoextraction experiment was250times higher than EDTA the eﬀect was minimal even for copper spiked soil.At the dosage used in phytoextraction,EDTA is equally ineﬀective. EDTA is only eﬀective at rates where toxic eﬀects are visible and leaching losses exceed plant uptake.In the slurry experiments the addition of62.5mM NLMWOA showed an enhanced mobilisation of copper in comparison to by the addition of0.125mM EDTA (Fig.3a),while the addition of NLMWOA showed very little eﬀect in the mobilisation of lead than EDTA (Fig.3b).Only citric acid(Fig.3b)at pH5mobilised a lot more lead than EDTA and oxalic and tartaric acid. One reason could be a combination of the low pH value and the salt carriage,as a result of the pH adjustment, which would result in higher heavy metal mobilisa-tion.Copper solubility increases with decreasing pH (Schmidt,2003).This individual experiment was repeated several times and the results were always the same.The column experiment underlined the great diﬀer-ence between the two metals copper and lead concerning their extractability by NLMWOA and the diﬀerence between the complexation capabilities of the NLMWOA tested.Lead mobilisation by NLMWOA was very low (Fig.4b).This supports the lead phytoextraction results that only EDTA was able to enhance the uptake.Cop-per mobilisation by NLMWOA,especially citric acid, was signiﬁcantly(P<0.05)higher than the copper amounts extracted by EDTA(Fig.4a).Regarding the potential of NLMWOA as shown in the column experiments,and in combination with the fact that the spiked soil used in the phytoextraction experiment had not passed a normal wet-dry cycle (2months),the uptake had to be much more enhanced. This indicates that this technique will probably fail underﬁeld conditions.The lack of high eﬃciency of the method was probably attributed to biodegradation of the NLMWOA.Which is reﬂected by the increase in pH,resulting from consumption of H+from carbox-ylic acids and liberation of OHÀand CO2(Gramss et al., 2004).This results in the lacking of complexing agents and a pH increase,which reduce the bioavailability of copper and lead.Copper is more mobile in soil than lead and therefore extracted from the plants before degrada-tion of the organic acids.To explain the ineﬃciency for the technique,the lacking access into the plant is ruled out,because,as in the case of EDTA(Grcman et al., 2001),their complexes are translocated via xylem from the roots to the shoots(Senden et al.,1990;Guo, 1995).The eﬃciency of the technique could be raised if the NLMWOA would be applied a few days before har-vest.But regarding the fact that approximately6g of cit-ric acid had to be applied on each pot makes the method rather expensive.Additionally,the bioavailability of metals is connected to the pH of the soil(Schmidt, 2003)and theﬁnal pH of the soil where NLMWOA were applied was approximately7.7,thus reducing the bioavailability of copper and lead.Therefore,making a continuous application of NLMWOA unsuitable for a clean up over several years.Alternatives to NLMWOA could be other biode-gradable chelating agents as nitrilo-triacetic acid (NTA)(Bolton et al.,1996)and[S,S0]-ethylenedia-mine–disuccinic acid(EDDS)(Jones and Williams, 2001).NTA is a very strong chelating agent compared to NLMWOA(Elliot and Denneny,1982),but neverthe-less the enhancement by a factor of2.5compared with the controls is insuﬃcient for phytoremediation applica-tions(Kulli et al.,1999).EDDS,a naturally occurring substance,isolated from Amycolatopsos orientalis (Nishikiori et al.,1984)has shown potential but the con-centrations achieved in Grcman et al.(2003)were still very far away from the concentrations required for eﬃ-cient phytoextraction.5.ConclusionNLMWOA,especially citric acid had a positive eﬀect on copper bioavailability and enhanced the copper uptake2.3-fold.In addition,they do not have the nega-tive eﬀects caused by phytotoxic EDTA such as the severe decrease in shoot biomass at very low concentra-tions in the soil.However,not only were they ineﬃcient in lead phytoextraction,but also the amounts of NLMWOA,which had to be applied to the soil before any eﬀect was visible,were high.In this aspect EDTA was much more eﬃcient.It is probable that the ready biodegradation of the NLMWOA was responsible for this lack of eﬃciency.They are probably degraded much too quickly to have the desired eﬀect NLMWOA are therefore not suitable for the enhancement of phytoex-traction,and will not serve as an economic alternative1002M.W.H.Evangelou et al./Chemosphere63(2006)996–1004to synthetic chelators.We will continue research in investigating other natural chelators to replace synthetic chemicals for this purpose.AcknowledgementsWe would like to thank the technical assistants,for their technical help during the research period and Ingolf Schuphan,Rong Ji,Philippe Corvini,Shelley Obermann,for their invaluable help.ReferencesBarona,A.,Aranguiz,I.,Elias,A.,2001.Metal associations in soils before and after EDTA extractive decontamination: implications for the eﬀectiveness of further cleanup proce-dures.Environ.Pollut.113,79–85.Bolton,H.,Girvin Jr., C.C.,Plymale, A.E.,Harvey,S.D., Workman,D.J.,1996.Degradation of metal–nitriloacetate complexes by Chelatobacter heintzii.Environ.Sci.Technol.31,860–865.Bouyoucous,G.J.,1952.A recalibration of hydrometer for making mechanical analysis of soils.Agron.J.43,434–438. Chen,H.,Cutright,T.,2001.EDTA and HEDTA eﬀects on cadmium,Cr,and Ni uptake by Helianthus annuus.Chemosphere45,21–28.Deutsches Institut fu¨r Normung e.V DIN19683Teil13,1997-03. Deutsches Institut fu¨r Normung e.V DIN38414Teil7,1983-01. Elliot,H.A.,Denneny,C.M.,1982.Soil adsorption of Cd from solutions containing organic ligands.J.Environ.Qual.11, 658–663.Evangelou,M.W.H.,Daghan,H.,Schaeﬀer, A.,2004.The inﬂuence of humic acids on the phytoextraction of cadmium from soil.Chemosphere57,207–213.Gramss,G.,Voigt,K.D.,Bergmann,H.,2004.Plant availabil-ity and leaching of(heavy)metals form ammonium-, calcium-,carbohydrate-,and citric acid-treated uranium-mine-dump soil.J.Plant Nutr.Soil Sci.167,417–427. Grcman,H.,Velikonja-Bolta,S.,Vodnik,D.,Kos,B.,Lestan,D.,2001.EDTA enhanced heavy metal phytoextraction:metal accumulation,leaching and toxicity.Plant Soil235, 105–114.Grcman,H.,Vodnik,D.,Velikonja-Bolta,S.,Lestan,D.,2003.Ethylenediaminedissucinate as a new chelate for environ-mentally safe enhanced lead phytoextraction.J.Environ.Qual.32,500–506.Guo,Y.,1995.Genotypic Diﬀerences in Uptake and Translo-cation of Cadmium and Nickel in Diﬀerent Plant Species.Verlag Ulrich E Grauer,Stuttgart.Huang,J.W.,Blaylock,M.J.,Kapulnik,Y.,Ensley,B.D.,1998.Phytoremediation of uranium-contaminated soils:role or organic acids in triggering uranium hyperaccumulation in plants.Environ.Sci.Technol.32,2004–2008.Jones,J.B.,Case,V.W.,1990.Sampling,handling and analyz-ing plant tissue samples.In:Westerman,R.L.(Ed.),Soil Testing and Plant Analysis,third ed.,Soil Science Society of America Book Series,vol. 3.Soil Science Society of America,Madison,WI,pp.389–427.Jones, D.L.,Darrah,P.R.,Kochian,V.L.,1996.Critical evaluation of organic acid mediated iron dissolution in the rhizosphere and its potential role in root iron uptake.Plant Soil180,57–66.Jones,P.W.,Williams,D.R.,2001.Chemical speciation used to asses[S,S0]-ethylenediamine–disuccinic acid(EDDS)as a readily-biodegradable replacement for EDTA in radiochem-ical decontamination formulations.Appl.Radiat.Isot.54, 857–893.Kaszuba,M.,Hunt,G.R.A.,1990.Protection against mem-brane damage:a H NMR investigation of the eﬀect of Zn2+ and Ca2+on the permeability of phospholipid vesicles.J.Inorg.Biochem.40,217–225.Krishnamurti,G.S.R.,Cieslinski,G.,Huang,P.M.,Van Rees, K.C.J.,1997.Kinetics of Cd released from soils as inﬂuenced by organic acids implication in cadmium avail-ability.J.Environ.Qual.26,271–277.Kulli,B.,Balmer,M.,Krebs,R.,Lothenbach,B.,Geiger,G., Schulin,R.,1999.The inﬂuence of nitrilotriacetate on heavy metal uptake of lettuce and ryegrass.J.Environ.Qual.28, 1699–1705.Lewandowski,J.,Leitschuh,S.,Kob,V.,1997.Schadstoﬀe im Boden.Springer-Verlag,Heidelberg.Marschner, B.,Henke,U.,Wessolek,G.,1995.Eﬀects of meliorative additives on the adsorption and binding forms of heavy-metals in a contaminated topsoil from a former sewage farm.Z.Pﬂanz.Bodenkunde158,9–14. Maywald,F.,Weigel,H.J.,1997.Biochemistry and molecular biology of heavy metal accumulation in higher plants.Landbauforsch.Volk.47,103–126.Mench,M.,Martin,E.,1991.Mobilization of cadmium and other heavy metals from2soils by root exudates of Zea-Mays L.,Nicotiana-Tabacum-L.and Nicotiana-Rustica L.Plant Soil132,187–196.Nelson,D.W.,Sommers,L.E.,1996.Total carbon,organic carbon,and organic matter.In:Sparks,D.L.,Page,A.L., Helmke,P.A.,Loeppert,R.H.,Soltanpour,P.N.,Tabata-bai,M.A.,Johnson,C.T.,Sumner,M.E.(Eds.),Methods of Soil Analysis:Part 3.Chemical Methods.,SSSA Book Monograph,vol.5.SSSA,Madison,WI.Nigam,R.,Srivastava,S.,Prakash,S.,Srivastava,M.M.,2000.Cadmium mobilisation and plant availability—the impact of natural organic acids commonly exuded from roots.Plant Soil230,107–113.Nishikiori,T.,Okuyama, A.,Naganawa,H.,Takita,T., Hamada,H.,Takeuchi,T.,Aoyagi,T.,Umezawa,H., 1984.Production by actinomycetes of(S,S)-N,N0-ethylene-diamine–disuccinic acid,an inhibitor of phospholipase.C.J.Antibiot.37,426–427.Pasternak,C.A.,1987.A novel form of host defense:membrane protection by Ca2+and Zn2+.Biosci.Rep.7,81–91. Raskin,I.,Smith,R.D.,Salt,D.E.,1997.Phytoremediation of metals:using plants to remove pollutants from the environ-ment.Curr.Opin.Biotechnol.8,221–226.Robinson,B.H.,Millis,T.M.,Petit,D.,Fung,L.E.,Green, S.R.,Clothier,B.E.,2000.Natural and induced cadmium-accumulation in poplar and willow:implications for phyto-remediation.Plant Soil227,301–306.Ro¨mkens,P.,Bouwman,L.,Japenga,J.,Draaisma,C.,2002.Potentials and drawbacks of chelate-enhanced phytoreme-diation of soils.Environ.Pollut.116,109–121.M.W.H.Evangelou et al./Chemosphere63(2006)996–10041003。

环境工程英语原文对照翻译

Reducing the Heavy Metal Content of Sewage Sludge by Advanced Sludge Treatment MethodsABSTRACTWaste-activated sludge (WAS) processes are key technologies to treat wastewater: their effluents can meet stringent discharge standards, thus ensuring a minimum residual impact on the aquatic environment. The presence of heavy metals in the excess sludge poses, however, serious problems, and considerably hampers the final disposal alternatives, especially in the agricultural use (soil improvement/amendment). This article studies the effect of thermal hydrolysis and Fenton’s peroxidation on the heavy metal content of the dewatered sludge. Acid thermal hydrolysis reduces the heavy metal content in the filter cake except for Cu, Hg, and Pb. Alkaline thermal hydrolysis releases Cu, Pb, and Cr. Fenton’s peroxidation transfers Cd, Cu, and Ni from the filter cake into the filtrate. Land application of the residual cake can hence be reconsidered.INTRODUCTIONWASTE-ACTIV ATED SLUDGE (WAS) processes are key technologies to treat wastewater: their effluents can meet stringent discharge standards, thus ensuring a minimum residual impact on the aquatic environment. Through their microbial activity, these biological processes produce huge amounts of WAS, now commonly called biosolids. This excess sludge is an inevitable drawback inherent to the WAS process. Increasing amounts of WAS have to be dealt with dueto (1) the higher wastewater collection rates, (2) the reliability and efficiency of wastewater treatment plants, and (3) the widespread application of denitrification and dephosphatation. The presence of heavy metals in the excess sludge poses, however, serious problems, since they are among the most important factors in assessing the final disposal alternatives of the sludge, for example, they will accumulate in the fly ash in the event of incineration, can be released through leaching in landfills, or may prevent land application.Many countries have imposed legal restrictions concerning the heavy metal content, when using the sludge for land application (e.g., agricultural use as fertilizer or soil amendment), since high concentrations in the sludge may result in heavy metal accumulation in cultivated soils. In the European Union, the maximum acceptable concentrations are fixed by the Directive 86/278/EEC of the European Commission (Commission of the European Communities, 1986). Most countries apply, however, a more stringent legislation. In Flanders, the standards are described in VLAREA (Flemish Government, 1997). Both European and Flemish legal standards, as well as the average concentrations of heavy metals in municipal sewage sludge in Flanders(Aquafin, 2004), are presented in Table 1. Some metals present in the WAS do not comply with these legal standards, thus necessitating the application of less sustainable and more expensive disposal routes.Heavy metals in sludge cannot be removed by common sludge treatment methods such as aerobic or anaerobic digestion.Some advanced sludge treatment processes (AST) were recently confirmed as having the potential to enhance the dewaterability of the sludge. The most promising techniques include acid and alkaline thermal hydrolysis (Neyens and Baeyens, 2003a; Neyens et al., 2003a, 2003b) and the peroxidation of the sludge (Neyens and Baeyens, 2003b; 2003c; Neyens et al., 2002). In addition, Dewil et al. (2005) demonstrated an increase of the thermal conductivity of peroxidated sludge, hence improving its drying characteristics. Neyens et al. (2004) concluded that these techniques enhance the dewaterability of the sludge by degrading the extracellular polymeric substances (EPS) structures. Since a large part of the heavy metals are bound to these EPS, the AST processes are supposed to also release heavy metals from the sludge to the water phase, thusreducing the heavy metal concentration in the residual sludge cake after dewatering. In doing so, the water phase needs a traditional treatment for metal removal (settling, flotation, etc.) prior to being recycled to the plant influent. This article studies the effect of thermal hydrolysis and Fenton’s peroxidation on the heavy metal content of the dewatered sludge.EXPERIMENTAL SETUP AND PROCEDURESludges usedThe experiments make use of thickened activated sludge samples, taken from the full-scale wastewater treatment plant (WWTP) of Leuven (located in Flanders, Belgium).The WWTP of Leuven is a high-load WAS plant having a sludge ODS/DS (organic fraction of the total amount of dry solids) fraction of 67%. No primary sedimentation is present.The activated sludge was collected and settled in the laboratory for about 4 h. The supernatant was thereafter poured off. The resulting dry solids content was about 3 wt.%.HydrolysisHydrolysis (acid or alkaline) of the sludge implies a treatment at moderate to high temperature. Acid thermal hydrolysis at low pH requires sulphuric acid (from a solution containing 1.75 kg H2SO4/L), whereas alkaline thermal hydrolysis occurs athigh pH, obtained by adding Ca(OH)2 (from a suspension containing 50 g Ca(OH)2/L). After reaction, the sludge is neutralized by adding Ca(OH)2 or H2SO4 for, respectively, acid or alkaline thermal hydrolysis. Ciba® ZETAG 7878 FS40 polyelectrolyte is thereafter added before dewatering the sludge.The experiments were carried out in a reactor, constructed as a pressure vessel with an electrically heated shell. The temperature of the sludge is kept constant. Samples of 10 L sludge were batch treated. Table 2 summarizes the operating conditions of the different treatment methods, previously determined to be optimal conditions (Neyens et al., 2003a, 2003b).Fenton’s treatment of the sludgeNeyens et al. (2002, 2003c) showed that the optimum activity for the peroxidation is reached under the following conditions: (1) addition of 25 g H2O2 kg-1DS, (2) the presence of 1.67 g Fe2+kg-1DS, (3) at pH 3 and (4) at ambient temperature and pressure.This treatment was carried out by first adjusting the pH of the sludge to 3 using H2SO4·Fe2+(i.e., FeSO4) was added at the given concentration and H2O2 was thereafter added at the required amount from a solution containing 390 g H2O2/L solution.The mixture was stirred at 200 rpm. The oxidation releases reaction gases (mostly CO2, H2O, and small organic molecules), and the time of reaction was considered as the time until the gas production was stopped. This time was about 60 min. After reaction, the sludge mixture was neutralized with Ca(OH)2 and polyelectrolyte (PE) was added. The PE used was Ciba® ZETAG 7878 FS40. The tests were performed in a batch reactor of 10 L.DewateringThe sludge was dewatered using a vacuum-assisted Buchner filtration at a vacuum pressure of 0.5 bar, assessed for a 100-mL sample during a set time of 5 min. The filter cake was analyzed for heavy metals.Heavy metal analysisCr, Cu, Ni, Zn, Cd, and Pb were measured by ICPOES. Hg was determined by cold vapor atomic absorption spectroscopy (AAS). Prior to the analysis, the sludge samples were submitted to a microwave destruction method. Approximately 0.2 g was introduced in a Teflon tube. Two milliliters of HNO3 (65 wt.%)6 mL of HCl (fuming), and 2 mL of HF were added. The tubes containing the mixture were inserted in a microwave oven, applying a power of 400 W for 20 min. Thereafter, 22 mL of 4wt.%boric acid was added to neutralize the remaining (hazardous) HF.RESULTS AND DISCUSSIONGeneralitiesHeavy metals in sewage are concentrated in the sludge through two treatment steps (Brown and Lester, 1979): (1) primary settling removes a proportion of metals which is either insoluble or adsorbed onto particles (Oliver and Cosgrove, 1974), and (2) additional metal removal occurs in the WAS process by the adsorption (biosorption) of dissolved or finely suspended metal compounds onto sludge flocs (Oliver and Cosgrove, 1974; Yoshizaki and Tomida, 2000). Some authors report that the activated sludge process is more efficient in removing metals than the primary settling.Biosorption of the heavy metal ions in the WAS process seems to take place mainly by the rapid ion exchange reactions on cell surfaces (Yoshizaki and Tomida, 2000). The surfaces of the micro-organisms in the activated sludge are covered with EPS. The potential binding sites for heavy metals on the EPS include carboxylates, amines, thiols, phosphates, and other functional groups (Seki et al., 1998). EPS hence act as ion exchangers which combine cationic and anionic exchange functions, and this action seems to facilitate the combination of sludge with various metal cations and metal complex anions. By degrading the EPS, it was assumed possible to release heavy metals from WAS.The treatment of the sludge with AST methods affects the extractability of the heavy metals present in the thickened sludge by two possible mechanisms: (1) the EPS mechanism or biological mechanism, and (2) the physicochemical mechanism.The high molecular weight EPS of the Biofloc includes polysaccharides, proteins, nucleic acids, lipids, and other polymeric compounds, and provide many functional groups that may act as binding sites for the metals (Forster and Lewin, 1972; Cheng et al., 1975; Brown and Lester, 1979; Liu et al., 2001). The AST methods have the potential to degrade the EPS, thus destroying the binding sites. Heavy metals are thus released. The process of destroying the EPS by AST methods is described in detail by Neyens et al. (2004).Physical and chemical factors affecting metal removal are temperature, pH, duration of acidification, presence of an oxidant, concentration of complexing agents, WAS floc size, etc.Heavy metals occur in different forms: exchangeable, bound to carbonates, bound to iron and manganese oxides, bound to organic matter, and residual (Naoum et al., 2001). The exchangeable fraction is likely to be affected by changes in water ioniccomposition, as well as by sorption and desorption processes. The carbonate fraction is sensitive to changes in pH, while the reducible fraction, which consists of iron and manganese oxides, is thermodynamically unstable under anoxic conditions. The organic fraction can be degraded, leading to a release of soluble metals in an oxidizing environment. The residual fraction, containing mainly primary and secondary minerals, holds metals within its crystal structure. The metals that are associated with the residual fraction are normally not expected to dissolve.Sludge hydrolysisAcid thermal hydrolysis. In comparison with the untreated sludge, the heavy metal content in the filter cake of acid hydrolyzed sludge is significantly reduced for most of the heavy metals, with the exception of Pb, Cu, and Hg. From the results in Table 3, the order of metal removal is: Zn=Ni>Cd>Cr>Pb> Cu>Hg.This order of removal roughly follows the general pattern of the Irving-Williams series (Irving and Williams, 1948), which describes the relative order of metal–organic chelate bond strengths. Often used in describing the soil chemistry of metals, the series predicts that metal–organic bond strengths are in the order Cu >Ni> Zn>Cd; and that the greater the organic bond strength, the less soluble the complex. This series predicts that cadmium is the most soluble metal, followed by zinc, then nickel, with copper being the least soluble. This is illustrated in Table 3, where the removal efficiencies of nickel, zinc, and cadmium are shown to be rather high due to the fact that acid thermal hydrolysis can break theNi, Zn, Cd–organic chelate bonds. Copper forms the highest fraction in the filter cake, since the acid treatment is not capable of releasing this metal from the Cu–organic structure. As in the case of acidification, neutral thermal treatment of sludge samples is also reported to result in a reduced heavy metal content in the filter cake and in the transformation of the remaining heavy metals from the mobile fractions to a more stable phase (Naoum et al., 1998, 2001).Heavy metals, incorporated in the sludge flocs, can only be transported from the flocs to the aqueous phase by diffusion. An elevated temperature could possibly increase the rate of extraction as the diffusivity of ions is promoted at high temperatures (Veeken and Hamelers, 1999). Conformational changes of sludge flocs could possibly contribute to an improved transport of metal ions within the sludge flocs or an enhanced accessibility of the acid anion. The increased rate of extraction of heavy metals at higher temperatures confirms the hypothesis that the rate of extraction is controlled by diffusion of metal ions from the sludge flocs to the bulk solution (Veeken and Hamelers, 1999).Alkaline thermal hydrolysisThe results in Table 3 show the following order of removal efficiency from thesludge phase: Cu>Pb>Cr>Zn>Cd=Hg=Ni. This is the same order as found by Hsiau and Lo (1997, 1998), who studied the leaching behavior of lime treatment. Lime treatment (Ca(OH)2) of sewage sludges is an alkaline treatment process which has been used for decades to reduce the odor generation and pathogen levels of biological matter.Hsiau and Lo (1997) demonstrated that the higher affinity for organics the heavy metals had in unlimed sludge, the more unstable the heavy metals were in lime-stabilized sludge. As a consequence, the amounts of originally bound metals in unlimed sewage sludge and the percentage of heavy metals extracted from lime-stabilized sludge were in the same order. This result was suggested to be attributed to the reversible dissolution of some strongly organically bound metals (e.g., Cu) at very high pH. The higher percentage of Cu extracted from alkaline-treated sludge (Table 3) was consistent with the known affinity of Cu for organic ligands according to the Irving-Williams series (Irving and Williams, 1948).Worth mentioning is the fact that the hydroxyl ion concentration affects the equilibrium of metal ions in solution, acting as a ligand with an affinity for the central metal ion and competing with other ligands. When the pH is increased to a level at which other ligands can no longer successfully compete with the hydroxyl ion, the metal will precipitate from the solution as an insoluble metal hydroxide (Cheng et al., 1975).Fenton’s peroxidationThe experimental results when applying Fenton’s peroxidation are presented in Table 4. The extractability of Cd, Cu, Ni, and Zn is increased using peroxidation in an acid environment. The removal of copper rapidly increases in the presence of hydrogen peroxide (Yoshizaki and Tomida, 2000): copper is an element having a strong affinity for organics (Wozniak and Huang, 1982; Naoum et al., 2001), and is released when the Fenton’s reagent degrades the organic matter.The removal efficiency of zinc is also enhanced. This release of zinc into the water phase is caused by a decrease in the proportion of organic and sulphidic phases (Brennan, 1991). The organic matter is degraded by the oxidative treatment and the zinc ions are, hence, released (as in the case of Cu). The peroxidation also transforms the insoluble zinc sulphides into soluble sulphates. The increased removal of zinc is enhanced by the increase in the carbonatic phase, which is solubilized into the water phase at pH 3.Cadmium is also mobilized into solution. Cadmium has been found to have a high affinity for chloride ions (Brennan, 1991).As far as other heavy metals are concerned, the efficiency of releasing the heavymetals does not significantly alter by addition of hydrogen peroxide. In the case of lead, however, oxidation may have caused the rapid degradation of organic matter (lead has a high affinity for organics) and the dissolution of sulphides (as sulphates), releasing lead which is subsequently precipitated as lead sulphate, carbonates, or adsorbed onto iron or manganese oxides (Brennan, 1991).It should be remembered that to prevent problems with heavy metals in the biological treatment facility, the sludge filtrate will need to be subject to metal precipitation and separation prior to being recycled to the WWTPinfluent. Fortunately, the filtrate recycle stream represents 2.5% only of the WWTP influent, thus facilitating this additionally required treatment step.CONCLUSIONSThis paper studied the effect of advanced sludge treatment methods on the heavy metal content of the dewatered sludge. As a result of the different treatment methods, the concentrations of several heavy metals in the sludge cake are significantly lower than in the untreated sample. It is, therefore, more likely that the residual cake can be used for land application. Acid thermal hydrolysis significantly reduces the heavy metal content in the filter cake except for Cu, Hg, and Pb. Alkaline thermal hydrolysis releases Cu, Pb, and Cr, whereas peroxidation releases Cd, Cu, Ni, and Zn from the filter cake and transfers these heavy metals into the filtrate.用高级污泥处理技术减少污泥中重金属的含量摘要活性污泥处理是污水治理的关键技术：其排出污水可以满足严厉的标准，从而保证对水生环境的残留影响减到最小。

(完整版)环境工程_毕业设计外文翻译_

毕业设计外文资料翻译外文出处：Ana Kleibe Pessoa Borges,Sâmia Maria Tauk-Tornisieloe,Performance of theConstructed Wetland System for the Treatment of Water from the CorumbataíRiver.BRAZILIAN ARCHIVES OF BIOLOGY AND TECHNOLOGY. Vol. 51, n.附件：1.外文资料翻译译文2.外文原文题目2000m3d温泉旅游度假区污水处理工程的初步设计院（系）化工与环境工程学院专业环境工程班级环境08-1学号学生陈灿辉指导教师陈梅芹（讲师）2012 年 6 月15 日附件1：外文资料翻译译文人工湿地系统处理科伦巴塔伊河水的效果Ana Kleiber Pessoa Borges1, Sâmia Maria Tauk-Tornisielo1*,Roberto Naves Domingos1 and Dejanira de Franceschi de Angelis2摘要这次实验目的是通过科伦巴塔伊河水处理的模拟实验研究人工湿地系统对水的处理。

分析系统在不同点的氨氮，生化需氧量（BDO）化学需氧量（CDO）的，氯化物，色度，电导率，溶解氧，镁（Mg），钠（Na），钾（K）硅（Si），总磷，总大肠菌群和大肠埃希氏菌，总溶解固体（TDS），混浊度，植物生物量等的参数。

结果表明，这种水处理系统能有效消除微生物（总大肠杆菌和大肠杆菌），通过其他参数之间的分析，在不同的处理阶段，理科伦巴塔伊河的水质得到明显的改善。

关键词：水生植物，土壤过滤，微滤，膜生物反应器，微生物引言由于城市规划不足，污染不断的快速增长，水资源浪费，水的再生利用不足和缺乏有效的环保教育，水资源已日益变得稀缺。

在开始讨论水质目标时，根据分类系统水资源的调控利用作为一个有用的工具在环境理事会的决议（Souza和Tundisi，2003年）被提出。

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。

环境科学与工程专业英语部分课文翻译(3、8、10、15、16、19、23)

Unit 3 What is Waste Reduction/Waste Minimization?什么是废物减量化，废物最少化美国花费了大量的时间在讨论像资源减量化，废物最小化，循环和阻止污染这些术语上，EPA已经提供了以下的定义。

资源减量化：减少在于一个过程中的大量废物的任何行为。

它包括，例如，过程调整，原料调整，提高管理和回收内在循环。

废物最少化：产生的废物最大程度减少，然后处理，存储，或者处置。

它包括了被导致了只要减量化与现在或将来威胁到人类健康和环境的最小化的目标一致的总容量或废物数量的减少或者废物毒性的减少，或者两方面兼备的发生器承担任何资源减量化或循环的活动。

回收：作为一个商业产品的代替品，或作为一个工业过程的原料的利用或再利用。

它包括了废物的有用的小部分或来自允许再用的去除了污染物的废物的在现场或离开现场的回收利用。

污染的防止：污染可能在生产过程之中产生，或者在当一个产品被用作商业用途或被消费者使用的时候产生。

这样可能在三个方式上被阻止：改变投入/减少依赖有毒物或有害的原材料；改变过程/增加效率/提高类似设备修改的维修保养，更好的管理，在过程中闭环循环；或者改变产出/减小对有毒或者有害产品的依赖。

随着1984年危险废物和固体废物修正案资源保护和恢复法的通过，美国国会建立一个国家政策来表明回收或消除危险废物的产生重要性。

美国国会宣称它是一项无论在美国哪里都可行的国家政策，要尽可能迅速地回收或消除危险废物的产生。

然而产生的废物还是应被处理、储存或处置，从而尽量减少现在和将来对人类健康和环境的威胁。

在1990年，美国国会通过污染防治法，建立了一个全国废物管理政策。

表明第一污染应该被预防或回收；;第二，废物应该用一种环保安全的方式进行循环利用；第三，废物应该被处理;最后，废物应该被除去或降解到环境。

在美国，随着这些和其他环境法规的通过，废物最少化成为一种重要的工作理念.废物回收/废物最少化技术同时，对于一些特定的工厂，废物最少化的当然是在具体的工厂或在实地，能用的技术能被分为以下主要几类：●product changes产品改变●process changes过程改变●equipment modifications设备改造●operating practices操作训练●recycling and reuse回收和再利用在实践中，尽量减少废物的机会是有限的，只有被工厂人员的聪明才智所利用. 这种技术已经被运用与大数量的工业和工业化生产过程，同时也被应用于有危险性和非危险性的废物。

环境工程专业英语Unit19的翻译

Text:Everybody’s Problem—Hazardous Waste每个人的问题——危险废物Every year ,billions of tons of solid wastes are discarded in the United Stastes. 美国每年丢去10亿吨的固体废物。

These wastes range in nature from common household trash to complex materials in industrial wastes ,sewage sludge ,agricultural resideus ,mining refuse and pathological wastes from institutions such as hospital and laboratories.这些废物的变化范围在平常家庭产生的垃圾到工业废物的复合材料、污水、农业废渣、矿渣和像医院、实验室这种大型机构产生的病理废物。

The U.S Environmental Protection Agency(EPA) estimated in 1980 that at least 57 million metric tons of the nation‟s total waste load can be classified as hazardous. 1980年EPA估计一个国家负载的全部废物的至少5700 0000公吨会被列为危险废物。

Unfortunately,many dangerous materials that society has “throw away” over recent decades have endured in theenvironment-making household words of “Love Canal”and”Valley of the Drums.”不幸的是在最近几十年中社会持续扔掉了许多危险物，从而产生了“爱河”和“桶谷”的家用词。

《环境工程专业英语》马志毅编中文翻译

1. The Environment and Environmental Engineering环境和环境工程学Simply said, the environment can be defined as one's surroundings. In terms of theenvironmental engineer'sinvolvement, however, a more specific definition is needed. To the environmentalengineer,the word environment may take on global dimensions, m ay refer to avery localized area in which a specific problem must be addressed,or may, in the case of containedenvironments,refer to a small volume of liquid, gaseous,or solid materials within atreatment plant reactor.简单的说，环境可以定义为我们的周围。

但是就环境工程师参与的角度来说，需要一个更加明确的定义。

对于环境工程师来说，环境这个词可能包含全球范围；也可能专指非常局部的一个地区，在这个地区中涉及到一些具体要解决的问题；或者也可能在密闭的环境中，指处理厂反应器内的一小块液体、气体或固体。

The global environment consists of the atmosphere, thehydrosphereand the lithosphere inwhich the life-sustaining resources of the earth are contained. The atmosphere, a mixture of gasesextending outward from the surface o f the earth, evolved from elementsof the earth that weregasified during its formation and metamorphosis. The hydrosphere consists of the oceans,the lakesand streams and the shallow groundwater bodies that interflow with the surface water.Thelithosphere is the soil mantle that wraps the core of the earth.全球环境由大气圈、水圈和岩石圈所组成，其中包含了维系地球上生命的资源。

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。

环境工程英文期刊(翻译版)

SCCPs（短链氯化物石蜡）是氯化程度不等的直链和支链C10-C12烷烃的复杂混合物。

他们主要的用途包括切割和用于散热的机油以及塑料中的阻燃剂。

SCCPs（短链氯化物石蜡）最早是用于二战中的阻燃军服。

如今，SCCPs是一种高产化学药剂，每年在美国和欧洲的总产量估计在7.5到11.3万吨。

中国被普遍认为是最大的氯化石蜡生产国，估计有140个工厂，且仅在2007年的产量就有60万吨。

然而，因为CP也可以是中等（C14 C17）和较长（C17）的长链，它是很难弄清短链氯化石蜡在中国的生产总量中的百分比。

根据欧洲委员会指令76/769/EEC和美国环保局最近宣布了一项行动计划，短链氯化石蜡的使用在欧洲将会被限制，禁止或限制短链氯化石蜡的生产和使用的持久性，由于生物蓄积性和毒性问题（//OPPT existingchemicals的的/酒吧/actionplans，/sccps.html）。

联合国欧洲经济委员会还列出了2009年到1998年议定书“关于持久性有机污染物（POPs）的附件一和附件二的短链氯化石蜡（http://www,/fileadmin/DAM/env/docume nts/）。

此外，在2011年10月，短链氯化石蜡增加了附表1加拿大环境保护法（http://www.gazette.gc.ca/rp-pr/p2/2011/2011-10-12/ html/sor-dors212-eng.html），在2012年，他们也被提议列入加拿大禁止某些有毒物质的法规（http://www.gazette.gc.ca/rp-pr/p1/2011/2011-07-23/ html/REG1-eng.html）。

在2007年，短链氯化石蜡被提议纳入《斯德哥尔摩公约》。

这个公约生效于2004年5月，是一个旨在保护人类健康和环境免受持久性有机污染物的风险的全球性的条约。

在2007年的会议上，有机污染物审查委员会对短链氯化石蜡的风险草案进行了审查，以评估该物质是否符合纳入公约的条件。

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。

（完整版）（整理）环境工程专业英语翻译（中英对照）

（完整版）（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，but which 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。

环境外文文献,附翻译

Ecological Engineering 47 (2012) 189–197Contents lists available at SciVerse ScienceDirectEcologicalEngineeringj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /e c o l e ngReviewApplication of constructed wetland for water pollution control in China during 1990–2010Ting Zhang a ,b ,Dong Xu a ,Feng He a ,Yongyuan Zhang a ,Zhenbin Wu a ,∗a State Key Laboratory of Freshwater Ecology and Biotechnology,Institute of Hydrobiology,Chinese Academy of Sciences,Wuhan 430072,PR China bGraduate School of Chinese Academy of Sciences,Beijing 100049,PR Chinaa r t i c l ei n f oArticle history:Received 18February 2012Received in revised form 12May 2012Accepted 22June 2012Available online 21 July 2012Keywords:Constructed wetland China ProjectWastewater treatmenta b s t r a c tConstructed wetlands (CWs)have been used in ecological engineering for more than two decades,since 1990.In order to understand the present application and trend of CWs in China,this paper summarized the status quo,prospect and inﬂuencing factors in CWs construction,technology application and opera-tion management in China,according to the data obtained by literature survey.Results of the systematic survey showed that CWs technology achieved gradual perfection under pushes of national policies,mar-ket demand and technical feasibility,with the capacity of wastewater treatment increasing year by year.However,there were still some problems concerning engineering operation and management.Moreover,the results demonstrated that limited by the economic level,the degree of industrialization and urbaniza-tion,climatic conditions as well as land availability,CWs were distributing predominately in the region of 20◦13 N–35◦20 N in China,where covered the central areas with a subtropical monsoon climate and southern or central areas at province level.In these areas,there were more than 40plant species,which accounted for 57.14%of the total number of common wetland plants.Most of the CWs composted series or parallel combination forms of the vertical ﬂow and free water surface ﬂow CWs units,and they were suitable to treat more than 20different types of wastewater.For these CWs,the efﬂuent chemical oxygen demand (COD),biological oxygen demand (BOD),total nitrogen (TN)and total phosphorous (TP)reached in the ranges of 20–60mg/L,4–20mg/L,1–20mg/L and 0.2–1mg/L,respectively.The efﬂuents from CWs were reused in more than eight ways,such as for agricultural irrigation,supplying surface water,green belt sprinkling,etc.© 2012 Elsevier B.V. All rights reserved.1.IntroductionConstructed wetlands (CWs)are artiﬁcial systems designed to simulate the function of natural wetlands for water quality improvement.The three main compositions of CWs are substrates consisted of sand,gravel and other materials in appropriate propor-tion,a variety of microorganisms and selected pollution-resistant plants.The wastewater is puriﬁed by the physical,chemical and biological triple synergy of the natural ecosystem (U.S.EPA,1993).In the early ﬁfties of twenty century (Haberl et al.,1995),Käthe Seidel conducted the ﬁrst experiment to purify domestic wastewater using macrophytes in Germany.Thereafter,in order to meet Europe’s stringent efﬂuent discharge standards,a number of experiments utilizing different kinds of CWs to degrade various pollutants in wastewater were conducted (Haberl et al.,1995).Till∗Corresponding author.Tel.:+862768780675;fax:+862768780675.E-mail address:wuzb@ (Z.Wu).the early 21st century,CWs technology can be used to dispose more than 20different types of wastewater in Europe (Vymazal,2011).China,locates in the east of Asia,possesses 9.6million square kilometers land area and 13.71million population (2011),and cov-ers a variety of climate types.Since the 1990s,China experienced booming economy and rapid urbanization,along with the grow-ing quantity and expanding distribution of wastewater (MEPPRC,2009,2010a,b ),the conventional wastewater treatment technol-ogy was incapable to solve all kinds of water pollution problems.Given China’s unique historical background and present situation of social economic development,the CWs technology has been considered as one of the most important ecological wastewater treatment technologies in China,with the advantages of low invest-ment and cost,high efﬁciency and better ecological services (Mitsch et al.,1993).Thus,CWs were introduced into China to strengthen the national efforts for water pollution control.The ﬁrst Shenzhen Bainikeng constructed wetland was com-pleted and operated in 1990in Canton,China (Green and Martin,1996;Li et al.,2007;Wang,1997;Yang et al.,1995;Zhang et al.,2009).Wu et al.(ERBIC18CT960059)developed a new type of0925-8574/$–see front matter © 2012 Elsevier B.V. All rights reserved./10.1016/j.ecoleng.2012.06.022190T.Zhang et al./Ecological Engineering 47 (2012) 189–1975101520253035199019911992199319941995199619971998199920002001200220032004200520062007200820092010Yea rA n n u a l a m o u n t o f C W s /s e t s .Fig.1.Annual quantity of constructed wetlands in China.integrated vertical ﬂow CWs and carried out pilot study in Wuhan,Hubei province,to treat eutrophic lake water,with the support of an EU cooperation project.Since then,the CWs technology has been widely used to handle many types of wastewater in China (Wu et al.,2002).In order to build a platform for CWs technology com-munication,the ﬁrst “Water protection and water pollution control technology,international workshop”was held by the National Sci-ence and Technology Department in Wuhan,China in 2004.And the ﬁrst “Cross-Straits wetlands seminar”was organized in Wuhan in 2008(Liu et al.,2008a ).Subsequently,the second and third seminar was respectively organized in Kaoxiong in 2009(Chinese Society for Environmental Sciences,2009)and in Hainan in 2010(Xu et al.,2010).The professional communication for CWs technol-ogy has greatly improved the development and application of the CWs technology in China.Based on the literature survey method,this research investi-gated the published and reported data of CWs in China in the last two decades from 1990to 2010,analyzed the construction and management of different types of CWs system,the status,factors and trends of common wetland plant species,and made recom-mendations to the application and development of CWs technology in China.2.Investigation methodFor the past 20years,the number of CWs in China has been growing rapidly,which makes it extremely difﬁcult to estimate the accurate quantity.As the literature survey method has the advan-tages of large span of space and time,being objective,time and expense saving as well as higher efﬁciency (Shui et al.,2010),this investigation study used the literature survey procedure to conduct the sampling investigation about the cases of CWs in China.The ﬁrst step is to retrieve cases of CWs published and reported from 1990to 2010,and then to conduct the statistical analysis for the engi-neering data got by the means of browsing,screening,reading,and etc.Machine-readable cataloging (MARC)was selected as the primary retrieval method,combining with expert consultation method to collect relevant public published literature about the CWs in China,from a multiple perspective.The concrete search channels are:(1)to consult related books through Wuhan docu-mentation and information centre of Chinese academy of sciences on-line public directory retrieval system;(2)to retrieve learnedperiodicals in Chinese periodical full text database (CJFD),Wanfang data,the CQVIP information resource system,Elsevier,Springer and Web of Science and some other main databases;(3)to retrieval public project information with the aid of web search engines of Google and Baidu;(4)to gain the proceedings of the ﬁrst,sec-ond and third session Cross-Strait Wetland Symposium through the specialized organization.At the same time,this investigation selects “the artiﬁcial wet-land/project”,“the constructed wetland/project”,“the construction wetland/project”,“the reed bed system/project”and “the vegeta-tion ﬁlter bed/project”as the retrieval key words,to expand the sampling size and reduce the sampling error.Till November 18,2011,this investigation collected 425CW project case samples in China.3.The situation and trends of CW’s construction and management in China3.1.The quantity of constructed wetlands in ChinaThe survey data in Fig.1demonstrated:from 2000,the quantity of CWs engineering in China was growing swiftly in South China (Shi et al.,2004)and in part of northern areas (Li and Jiang,1995),especially the areas having the middle and small scale cities.At the same time,since 1998,the number of the project built annually was signiﬁcantly higher than the number to be built.In addition,from 2000to 2010,the annual growth rate of the completed CWs was signiﬁcantly higher than that of the number in planning.The above results indicated that the CWs technology was developed year by year in wastewater treatment,the engineering application became more popular day by day.3.2.The capacity of CWs for wastewater treatmentSince 2003,the National bureau of statistics and the Ministry of Environmental Protection of China began to investigate the con-struction and management of the wastewater treatment plants (WWTPs,represented by activated sludge process)annually and regarded the treatment capacity as one of the key indicators to evaluate the contribution and technical suitability for water pollu-tion control of the nation.The data of WWTPs in this study were collected from the ofﬁcial publication.According to the literature survey,a non-linear regression model was established by usingT.Zhang et al./Ecological Engineering47 (2012) 189–197191parison of annual wastewater treatment capacity of constructed wetlands and wastewater treatment plants in China.Notes:The data of WWTPs in China comes from National Bureau of Statistics(NBS,2003–2010).regression analysis with the annual wastewater treatment capac-ity as the dependent variable(in Y)and the number of years as the independent variable(in X,with2003as the baseline year),to examine the degree and trend of the contribution of CWs system for water pollution control.The statistical results showed that the wastewater treatment capacity of CWs systems were lower than those of the WWTPs from 2003to2010(Fig.2).The WWTPs were still the main approach in China,while CWs systems have being widely used in theﬁeld of small-scale water pollution control.By2010,the gross of wastew-ater treatment by CWs accounted for0.82%of the total value of the two processes(Fig.2).In addition,the results of nonlinear regression analysis in Fig.2 showed that the regression equation of CWs wastewater treatment capacity was Y=2.2143X1.8009(R2=0.9695).The regression equa-tion of wastewater treatment capacity in sewage treatment plant was Y=37.219X2+509.88X+3744.3(R2=0.9991).The conﬁdence level of the two regression equations were both greater than95%, which indicated that there were similar regularity and trend in the change of annual treatment capacity between CWs systems and WWTPs.At the same time,the results showed that,since2003, the growth rate of CWs wastewater treatment capacity was signif-icantly higher than that of WWTPs.On the whole,as the capacity of CWs wastewater treatment increased every year in China,the con-trol power and contribution level of the system for water pollution control would increase year by year in China,to help promote the application of CWs technology.At the same time,the survey showed that CWs system has been used in more than30%areas of China.The treatment scale of CWs in China ranged from1000m3/d to20,000m3/d.These CWs were located in more than13provincial-level administra-tive regions:Zhejiang(Liu,2009),Hubei(Wu,2008;Zhang et al., 2008),Yunnan(Deng et al.,2007;He,2006;He et al.,2009;Li et al.,2009;Xu et al.,2009),Shandong(Dezhou Daily Report, 2009),Inner Mongolia(Wulanhad Daily Report,2008),Zhejiang (Qiu,2009),Anhui(Cui and Lu,2009),Guangdong(Cui and Lu, 2009;He,2009;Li et al.,2007;Liang,2009;Mo,2009;Wang,1997; Yang,2008;Zhen et al.,2009),Fujian(MHUCSI,2009;Mo and Lin,2009;Wu,2008),Guangxi(Li et al.,2009;Ma and Liu,2007), Hainan(CENR,2007;Tian and Qing,2009),Sichuan(Chengdu Daily Report,2010;Huang et al.,2009;,2009;Sichuan Provincial People’s Government,2007;Tianfu Community,2007), Yunnan(Jin et al.,2008)and others.The data showed that the number of provincial-level administrative regions,where CWs project has been built,was more than13in China,accounting for38.24%of the total number of provincial-level administrative regions.Overall,the construction and industrialization power of CWs in China were mainly forced by the national policy,the mar-ket demand,technical feasibility and other factors.Taking the “Eleventh Five-Year”period(2006–2010)as an example,the national wastewater emission increased from53.68billion tons (MEPPRC,2006)in2006to61.73billion tons(MEPPRC,2010a,b)in 2010.The requirement for water pollution control was increasing. Therefore,China’s National Development and Reform Commission proposed policies in theﬁeld of environmental protection,such as “letting market mechanism begin to enter theﬁeld of environmen-tal protection;investing more than1%of the total GDP for national environmental protection for theﬁrst time”.The policies greatly supported the construction of the CWs.3.3.The issues of CWs operation and managementAlthough the construction number and annual treatment capac-ity of CWs system in China increased year by year,there are still many problems in many CWs,including that the system did not function properly due to low temperature,plant pest disasters, congestion,substrate surface hardening,water qualityﬂuctuation, large area requirements,the endogenous release of pollutants, long term for system stabilization,wetland structure leakage,pre-treatment not meeting the designed treatment efﬁciency,no water ﬂow control facilities,unevenﬂow distribution,low utilization capacity of wetland bed,long idle period,excessive plant growth and so on(MHUCSI,2009;Mo and Lin,2009;Wu et al.,2000).The problems mentioned above came from the natural or site engineering conditions,technical limitations,management and other confounding factors together.As to promote the application of CWs in China,the Ministry of Environmental Protection of China published a technical speciﬁcation of CWs(technical speciﬁca-tion of constructed wetlands for wastewater treatment engineering (HJ2005-2010)).If the speciﬁcation can be well implemented,the problems now aroused during the operation and management of CWs in China may effectively be reduced.4.Engineering applications of different types of CWssystemAccording to different patterns of waterﬂow,CWs can be divided into free-surfaceﬂow(FWS)and subsurfaceﬂow CWs (Fig.3).Subsurfaceﬂow CWs can further be divided into horizon-tal subsurfaceﬂow(HF)and verticalﬂow(VF)CWs(Vymazal and Kröpfelová,2008).Different types of CWs have different structures, which lead to the differences of the mechanism and efﬁciency of pollutant removal.Among the different types of CWs systems,the192T.Zhang et al./Ecological Engineering 47 (2012) 189–197Fig.3.Classiﬁcation of constructed wetlands (Vymazal and Kröpfelová,2008).free-surface ﬂow CWs belong to the horizontal ﬂow pattern,in which the bottom of the matrix can ﬁx the roots of aquatic plants,the water level is usually higher than the substrate surface,the dislodge of organic pollutants depends on the plant stems under water and bioﬁlms of the rod (Kivaisi,2001;Sundaravadivel and Vigneswaran,2001).On the other hand,the sewage in horizontal subsurface ﬂow CWs ﬂows through pores between the substrate,and the pollu-tants can be removed by the combined effects of microorganisms and substrate.Vertical ﬂow CWs,constructed with speciﬁc struc-tures such as pipes and slopes,let the sewage to ﬂow through the substrate layer ﬂuently as uniform and vertically,with the water distribution capacity higher,better oxygenation within the system,which favor the growth of aerobic microorganisms and promote the nitriﬁcation.Therefore,the removal rate of organic nitrogen matters is higher in vertical ﬂow CWs,compared to the other two CWs (Greenway,1997;Vymazal,2005;Wu,2008).In particular,a new type of vertical ﬂow CW,which is inte-grated vertical-ﬂow constructed wetland (IVCW),has been used for treating different wastewater in China (National invention patent of China,2000,No.ZL00114693.9).The core structure of the IVCW consist of two chambers,downstream and upstream,in series,to form a horizontal –downstream-horizontal–upstream-horizontal”multiple U-shaped ﬂow structure and process an “aerobic–anoxic–anaerobic–anoxic–aerobic”alternating multi-function layers,to achieve a gradient of physical,chemical and biological conditions for the substrate,roots,microorganisms and so on.The surface in the downstream chamber has inﬂuent dis-persing pipes,which allow the wastewater pass through ﬂuently and equally into the chamber,the sewage ﬂow downward ver-tically under gravity,and then cross through the bottom of the connectivity layer to reach the upstream chamber,followed by the vertical upward.The surface in the upstream chamber has collec-tion pipes,which are used to collect the efﬂuent.Two chambers are planted.The downstream substrate surface is generally higher than the upstream chamber.In addition,the results of the study indicated that the combina-tion of various types of CWs in different forms of systems (Fig.3)have been widely used to improve the efﬂuent water quality and removal efﬁciency in China,which are similar to those in many European countries (Vymazal,2005).To investigate the applica-tion status of the combined CWs systems in China,the combined CWs systems were divided into three types:in series,parallel and hybrid in this study.The combination with the same type of CWs technology is notincluded.Fig.4.Geographic distribution of three types of constructed wetlands in China.Notes :Color vertical bars represent number of three types of constructed wetlands in each provincial-level administrative area.(For interpretation of the references to color in this ﬁgure legend,the reader is referred to the web version of the article.)4.1.Regional distribution of different process types of CWsTo investigate the present status and inﬂuencing factors of the regional distribution of the three process types of CWs in China,the study,counted the number of three types of wetland systems in different provincial administrative regions,The statistical results showed that the three types of CWs systems have been applied in more than 80%of the provincial-level administrative regions in South China and along the coastal areas.In particular,the verti-cal ﬂow CWs system is prevalent in South China and almost all of northern coastal provincial-level administrative regions.Guang-dong and Hubei are among the nation’s top two in the number of CWs (Fig.4).Surface ﬂow CWs were mainly distributed in provin-cial administrative regions,such as Taiwan,Yunnan,Shandong and Liaoning.Overall,in the past 20years,the rapid economic development,industrialization and urbanization in the southern and coastal areas of China,resulted in higher pressure of water pollution,thus the application scope of the CWs technology has been extended in these areas.The Tsinling Mountains and Huaihe River are on the boundary of the northern and southern parts of China,a country with a vast territory (Wu,2001).In 1980,the gross national prod-uct (GDP)of the northern areas accounted for 90%of that of the southern areas.By 1999,the northern areas’GDP was less than 70%of that of the southern.Till the late 1990s,the economic growth in the southern and coastal areas of China was signiﬁcantly faster than that in the northern,which resulted in the emergency of new imbalance in the economic development between the northern and southern areas.In the 21th century,the economic level in the south-ern and coastal areas of China was signiﬁcantly higher than that in the northern,which indirectly led to the geographical differences in construction of CWs.On the other hand,the climatic conditions,land availability and other factors may also affect the regional difference of CWs engi-neering applications in China (Li and Jiang,1995;Liu et al.,2008b;Shi et al.,2004;Zhang et al.,2009).Moist climate in regions with rich plant resources,were suitable for the growth and reproduction of wetland plants,as well as the selection and graded combination of plant species for CWs.The construction of CWs would be limited by land availability in urban areas with high density of population (Kivaisi,2001).In addition,by 2010,different types of CWs were ranked as sur-face ﬂow constructed wetland (30.4%),horizontal subsurface ﬂowT.Zhang et al./Ecological Engineering47 (2012) 189–197193constructed wetland(25.20%)and verticalﬂow constructed wet-land(22.4%),according to the total number of CWs constructed in China from high to low.As China is currently in the process of urban construction,a large number of wastewater treatment facilities are needed urgently.Surfaceﬂow CWs has been used in many areas of China because of its lower construction and operation cost and shorter construction period compared to the other types of CWs. Meanwhile,the survey showed that the integrated verticalﬂow constructed wetlands(IVCWs)accounted for28.57%of the total number of verticalﬂow CWs in China.This type of CWs has been popularized successfully in dozens of cities and vast rural areas in China,including Beijing,Shanghai,Tianjin,Chongqing,Wuhan, Shenzhen,Hangzhou,Guangzhou,Xi’an,Changchun,Sanya,etc.4.2.Types of wastewater treated by CWsBecause of the limit by degradation ability of CWs when treating the complex inﬂuents,especially,low removal rate for wastewater contained the phosphoric organic matters(Sun et al.,2009);many cases could be found in China that the combination systems of dif-ferent types of CWs units were served as the second or the tertiary treatment facilities,for treating a variety of wastewater.4.2.1.Three type of CW applicationsThe result of this survey showed that,in the recent20years,the CWs systems have been used for treating as many as20kinds of wastewaters in China.According to the source of wastewater,it may be classiﬁed into domestic sewage,which included non-point source polluted water, aquaculture water,polluted lake and river water,landscape water, tailrace of WWTPs,composite wastewater,industrial wastewater and so on.Among all these types of wastewaters,the domestic sewage and polluted river water were the top two as the main purposes of CWs constructed in China(Fig.5).In addition,there was a few CWs system being successfully used in treating complicated wastewater,such as some indus-trial wastewater,landﬁll leachate and so on(Fig.5).To take Hubei Huang Gang Yongan pharmaceutical Co.,Ltd wastewater treatment project as an example(Wu,2008),this project was completed and operated in May,2008,with the treatment capacity300m3/d of pharmaceutical processes and domestic sewage mixture wastew-ater.The project consisted of the grill,the adjustment pool,the hydrolisis acidiﬁcation pond,the contact oxidation pond and the sedimentation pond as the pre-treatment units,and the IVCW technology as the second-level treatment unit.The water quality parameters of the efﬂuents reached COD≤60mg/L,BOD≤20mg/L, TN≤20mg/L,TP≤1mg/L.The statistical data indicated that,in the recent20years,the verticalﬂow and the surfaceﬂow CWs were the major technique types used to treat a variety of wastewaters,which was dominated by the domestic sewage(Fig.5).Since the beginning of21th cen-tury,China’s domestic sewage amount has accounted for above 50%of the total amount of national wastewater discharge,which was one of the main origins for water pollution.Because the ver-ticalﬂow CWs provided more uniform water distribution,higher area utilization ratio and better internal oxygenation which favored the growth of aerobic microorganisms and the nitriﬁcation process thus ensured high elimination rate of the nitrogen organic matters (Greenway,1997;Vymazal,2005),the number of this verticalﬂow CWs used for treating the domestic sewage was greatly higher than the other two types of CWs.Theﬁrst CWs project to use IVCW system in a large-scale for treating the domestic sewage in China was Shenzhen Shiyan reser-voir CWs treatment project(Liu et al.,2005).The project was completed in July2003and put into operation to treat sewage 55,000m3/d,with eight integrated verticalﬂow processing CWs units.The removal efﬁciency of COD,BOD,SS,TP,TN by this system reached87.1%,94.1%,91.4%,47.8%and74.8%,respectively.Second,because the surfaceﬂow CWs can remove the sus-pended solids by adsorption and settlement(Vymazal et al.,2006), result in low construction and operation cost as well as better landscape effect.This type of CWs has been largely applied to handle a variety of types of wastewater,particularly to treat low-concentration wastewater such as small city and town’s domestic sewage and polluted river in China(Fig.5).4.2.2.Engineering application of combined CWsThe present status that the combined-type CWs have been widely applied in Europe showed that different types of CWs tech-nologies can be combined,to combine their respective technical advantages to improve the system removal efﬁciency and impact resistance ability,and enhance the landscape effect.The statistical results showed that,in recent20years,the main combined types of CWs structure in China were in series and in hybrid,and both have been largely used in treating a variety of wastewaters such as domestic sewage(Fig.6).Among them,FWS CWs–VF CWs in series and FWS CWs–HF CWs in series were the dominant combination types.China’sﬁrst CWs project(Green and Martin,1996;Li et al.,2007;Wang,1997; Yang et al.,1995;Zhang et al.,2009)to treat sewage and industrial mixture wastewater31,000m3/d,has employed the hybrid CWs structure(Yang et al.,1995),with speciﬁc combi-nation of verticalﬂow(1512m2)–verticalﬂow(1739m2)–surface ﬂow(1710m2)–verticalﬂow(2850m2)(Liang,2009;Vymazal and Kröpfelová,2008).5.Distribution status of commonly used CWs plantsWetland plant is an important component in the CWs system. Plants can stabilize the substrate–surface structure of the wet-land,provide a good condition for physical adsorption,improve the hydraulic performance of the system,prevent the substrate surface freezing in winter in most central and southern areas,and provide more surface areas for microbes to inhabit(Brix,1997).The choice of CWs plants is generally made according to the environ-mental requirements for plant growth,the types of inﬂuent,the landscape effect of wetland system and so on.Among them,the growth and distribution of plants are closely related to the climate conditions at the location of the project(Woodward,1987).And the climate conditions mainly depend on the latitude of the loca-tion.Because China is mainly characterized with monsoon climate and continental climate,and it covers about50◦span from north to south(4–53◦N),with apparent regional climate feature and various types of plants distribution,this paper examined the relationship between the selection of plant type in the CWs with the region, climatic condition and latitude.The statistical results showed that,from1990to2010,the national optional wetland plant species were up to more than 70types(Table1).The plant species used in China’s CW systems presented diverse geographical distribution.The central and south-ern provincial-level administrative regions in the20◦13 –35◦20 N region,having the subtropical monsoon climate,hold the largest number of plant species,up to about40.The regions with mon-soon and tropical monsoon climate take the second place.Most of the regions used wetland plants dominated by pollution-resistant aquatic plants,such as Phragmites australis(Cav.)Trin.ex Steud.and Juncus effusus,Nymphaea alba,Canna indica,Scirpus mariqueter,etc. In tropical monsoon climate regions,such as Hainan,the local char-acteristic plants were consideredﬁrstly,such as the Heliconia Linn.。

环境工程专业英语文献中英双语版

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 flash plant is ～750 kg/s. The potential amount of steam condensate that could be produced at the plant is ～350 kg/s. Table1includes 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 thebuffering 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 beenconducted 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 produced water to drinking water or reuse. Paper presented at 1998 SPE Annual Technical Conference and Exhibition, 27–30 September. 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 of suspended 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 geothermal waters 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 cementation process. 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 drinking water, 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。

环境工程文献翻译（翻译）

序批式厌氧/缺氧/好氧工艺中同时去除磷，氮和二硝基甲苯环境工程系，工程学院，Dokuz Eylul大学，Buca Kaynaklar校园Tınaztepe- Izmir，土耳其2003年6月20日收到；在经修订的形式03年10月24日收到的；2003年11月22日被公认摘要在磷酸盐- P浓度增加至320毫克/升时，是通过化学耗氧量（COD），挥发性脂肪酸（VFA）消耗和二硝基甲苯（DNT）的去除在厌氧条件下发生的磷释放造成的。

当向NO3 - N比化学需氧量减少约2.0，废水的有机成分，主要是硝酸盐在缺氧条件下转化为甲烷。

这两个反硝化和PO4 - P浓度开始增加时，甲烷已经完成，开始产出氮气。

在缺氧条件下，聚磷细菌能利用挥发性脂肪酸去除磷酸盐，反硝化工艺处理主要完成后，化学需氧量为碳源，硝酸盐为电子受体。

随着进水中的COD为3000毫克/升，通过20天的孵化缺氧最大量可去除性磷酸盐为56毫克/升，表明98％的磷在这个反应中去除磷酸盐，PO4-P/NO3-N和PO4-P/COD消耗比例分别为0.08—0.2和2.3—2.6。

高硝态氮含量显着减少P的吸收。

非常低或非常高浓度的COD如500和7000毫克/升在缺氧条件下，磷的吸收显着减少。

DNT是通过厌氧条件下反硝化到氨氮，芳香胺和甲苯，而芳香胺，甲苯，氨对在好氧条件下最终矿化，通过整个连续厌氧/好氧工艺。

厌氧反应器中观察到二硝基甲苯的去除率为70％，同时，反硝化的磷释放和磷吸收过程中，二硝甲苯去除率分别为37和0.05％。

通过有氧培养获得的DNT去除率没有显著变化，但在缺氧条件下连续硝化/供磷过程中二硝基甲苯的去除率为50％。

他们还用作炸药中间体和制造橡胶和塑料化学[1]。

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