Bøger udgivet af IWA Publishing

CARE-W is a joint European initiative to develop a framework for water network rehabilitation. This book consists of software, dealing with fundamental instruments for estimating the condition of water networks, including tools to assess performance indicators (PI), to predict pipe failures (FAIL) and to calculate water supply reliability (REL).

Marking the end of the fifth phase of UNESCO's International Hydrological Programme, this book brings together scientific and professional players to address the critical issues in water management. It investigates themes such as the challenges of urban water management, infrastructure integration issues, and the paradigms in water supply.

During wet weather events, separate and combined wastewater collection systems deliver substantial amounts of storm water runoff to wastewater treatment plants. Often these flows inundate collection systems and treatment works creating bypasses of untreated or partially treated wastewater. The federal Clean Water Act (CWA), its amendments, and associated regulations have been attempting to address these concerns for nearly 30 years. These regulations, coupled with the wastewater treatment standards under the CWA, are posing immense challenges to the owner/operators of wastewater systems, who are also driven to provide the most cost-effective service to customers. This project (WERF Project 00-CTS-6, "e;Best Practices for the Treatment of Wet Weather Wastewater Flows"e;) undertook a review of currently available technologies to improve the performance and efficiency of wet weather wastewater treatment and also identified potentially beneficial technologies and methodologies that are emerging in this area. The project report includes the types and characteristics of current technologies and methodologies available to ensure treatment of wet weather wastewater flows. The following are the categories of technologies are assessed in report: vortex separation, enhanced clarification, operational enhancements, flushing systems, and disinfection.

Biological denitrification by heterotrophic bacteria is common in the wastewater industry in the U.S. and in drinking water processing in Europe. To facilitate heterotrophic denitrification, organic compounds such as methanol, ethanol and acetic acid are added to provide a carbon source for the bacteria. The resulting organic carbon residual may create problems with chlorination. The addition of these carbon compounds is expensive and results in added sludge production. This study focused on the use of autotrophic hydrogen oxidizing bacteria for denitrification. The method transfers hydrogen gas to solution via microporous hollow fiber membranes. Typically, gases are supplied to a system using conventional bubble diffusers. The conventional bubble aeration system has a low gas transfer efficiency, and, as a result, the cost of dissolving the required amount of gas is very high. In this study, microporous hollow fiber membranes were employed to supply hydrogen gas to hydrogen oxidizing autotrophic bacteria. Laboratory scale membrane modules were constructed and mass transfer studies were carried out to develop the design correlations for hydrogen gas transfer. A mixed culture was obtained and acclimated for batch denitrification studies. Both Sodium carbonate and carbon dioxide were used to deliver inorganic carbon. Bench scale continuous flow biofilm reactors containing plastic media were operated to remove nitrate from water. The required hydrogen gas was supplied at a constant rate via gas transfer modules, containing sealed end microporous hollow fiber membranes. The reactors were optimized for removal of nitrate and nitrite by varying the recycle ratios and hydraulic detention time. Experimental results indicated the presence of hydrogen oxidizing denitrifiers in wastewater sludge. Adequate pH control was possible and the pH averaged around 6.95. Gas transfer studies indicated that hydrogen transfer was primarily controlled by liquid film diffusion. Hydrogen gas was successfully delivered to the reactor via the hollow fiber membrane gas transfer module. Nitrate and hydrogen concentration measurements indicated that the system did not experience hydrogen limitations at detention times of 3.25 hours or greater. The use of hollow fiber membrane module appears to be a viable technology for transferring hydrogen gas to water. The research results in this report provide valuable information for pilot and full-scale studies for the water/wastewater community focusing on membrane processes for autotrophic denitrification.

The objectives of this project were to develop (1) a better understanding of the effects of storage on reclaimed water quality, (2) a methodology to help understand/predict water quality changes during storage, and (3) effective management tools for minimizing water quality problems. The research team reviewed approximately 120 published articles, conducted a gray literature survey to analyze the impact of surface storage on reclaimed water quality. The team also evaluated federal guidelines for reclaimed water and developed a brief update on what individual states are doing. It was determined that state and federal water quality objectives can be met at the treatment site. However, because of the seasonal nature of reclaimed water use, water often must be stored in open reservoirs, where changes occur that can affect water quality. The nature of these changes was evaluated, including physical, chemical, and biological processes. The research team evaluated several reservoir management strategies to improve water quality, and reviewed water quality models to assess their applicability for open reclaimed water storage reservoirs. It also developed procedures to evaluate and select management strategies and reservoir water, along with matrices to distill the information learned in the study into a useful format for risk assessors and water quality managers. These tools will enable users to readily equate their specific storage reservoirs to representative examples, and to identify actions most applicable to their specific reclaimed water systems.

The observed concentrations of pharmaceuticals and personal care products (PPCPs) in raw wastewater confirm that municipal wastewater represents the main disposal pathway for the PPCPs consumed in households, hospitals and industry. This book covers various aspects of the fate and removal of PPCPs in the whole water cycle.

Over 90% of bacterial biomass exists in the form of biofilms. The ability of bacteria to attach to surfaces and to form biofilms often is an important competitive advantage for them over bacteria growing in suspension. Some biofilms are "e;good"e; in natural and engineered systems; they are responsible for nutrient cycling in nature and are used to purify waters in engineering processes. Other biofilms are "e;bad"e; when they cause fouling and infections of humans and plants. Whether we want to promote good biofilms or eliminate bad biofilms, we need to understand how they work and what works to control them. Mathematical Modeling of Biofilms provides guidelines for the selection and use of mathematical models of biofilms. The whole range of existing models - from simple analytical expressions to complex numerical models - is covered. The application of the models for the solution of typical problems is demonstrated, and the performance of the models is tested in comparative studies. With the dramatic evolution of the computational capacity still going on, modeling tools for research and practice will become more and more significant in the next few years. This report provides the foundation to understand the models and to select the most appropriate one for a given use. Mathematical Modeling of Biofilms gives a state-of-the-art overview that is especially valuable for educating students, new biofilm researchers, and design engineers. Through a series of three benchmark problems, the report demonstrates how to use the different models and indicates when simple or highly complex models are most appropriate. This is the first report to give a quantitative comparison of existing biofilm models. The report supports model-based design of biofilm reactors. The report can be used as basis for teaching biofilm-system modeling. The report provides the foundation for researchers seeking to use biofilm modeling or to develop new biofilm models. Scientific and Technical Report No.18

This book provides concise, up-to-date and easy-to-follow information on an increasingly important area of hydro-environmental analysis and management. It covers important aspects of both surface and subsurface water quality management, as they are inseparable components of aquifers and the flow in physical domains occur in combination with the other. However, the main emphasis of the book is on the practical development and application of computer based algorithms, via appropriate schemes, to realistic problems. Mathematical theories are not discussed as they can be found in many expert books. All sections of the book include detailed descriptions of practical examples. It also, uniquely, gives explanations regarding the formulation of practical management schedules and tools for hydro-environmental systems. There is a lack of books dealing with the practical aspects of the application of computer modelling techniques to complex hydrodynamical phenomena, and this book has been written for professionals and researchers, especially those who are not trained mathematicians who, nevertheless, need to make managerial decisions.Computational Methods in the Management of Hydro-Environmental Systemswill be an invaluable source of information for post-graduate level researchers and decision-makers who need to apply numerical modelling techniques to investigate hydrodynamic phenomena andpollutants dispersion in natural aquatic systems. Professionals and engineers, who now need to gain insights about the working of computer techniques for choosing appropriate schemes and applying them to realistic problems, will also value this work. Masters' level and final-year graduate students are also expected to benefit from the book.

Deoxyribonucleic acid (DNA) microarrays are widely used for differential expression studies and for detection of virulence genes in pure bacterial cultures. Their use in complex microbial samples, such as soil and wastewater, has been relatively less studied. This report presents the results of a systematic effort to apply DNA microarrays to pathogen detection and to bacterial source tracking (BST) in wastewater. Parameters such as the method of DNA extraction from the samples, the type of immobilized probe (whether polymerase chain reaction [PCR] amplicons or oligonucleotides), the length and method of immobilization of oligonucleotides, the method of DNA labelling, the combination of PCR amplification with microarray hybridization and the choice of PCR targets have been optimized. Results indicate that the combination of PCR followed by microarray hybridization can detect pathogens in wastewater samples down to a 0.1% detection limit. The use of microarrays for bacterial source tracking gave promising results on human samples, however the probes used in this study only provided signals for general indicators of fecal contamination when used on samples of animal origin. The overall conclusion is that microarray technology has not yet reached the stage of routine use for microbiological analysis of wastewater. This report demonstrates: That the hybridization of total genomic DNA on microarrays has a high detection limit, of the order of 10^7 genomes; That the use of long oligonucleotides or PCR amplicons from 16S rDNA, or cpn60 probes has insufficient specificity to differentiate several important pathogens, especially within the Enterobacteriaceae family; That the use of short oligonucleotide immobilized probes coupled with PCR amplification of conserved genes, such as 16S rDNA, cpn60, or wecE, can detect pathogens in wastewater down to a 0.1% (DNA weight/weight) concentration; and The potential of DNA microarrays in BST, even if further research work remains necessary to achieve this goal.

The main objective of this project is to demonstrate that the technology of on line monitoring of waterborne metals by X-ray Fluorescence (XRF) at part per billion (ppb) and sub-ppb levels, which has been successfully applied in the power industry for several years, can be applied to water and wastewater treatment plants. A specially designed on line XRF monitor was assembled, tested in the laboratory, and used at the City of Alliance, Ohio Wastewater and Water Treatment Plants from July 2002 until March 2004. At various times through this project, the metals monitored included iron, copper, chromium, nickel, zinc, manganese, arsenic, cadmium, mercury and lead. The results indicate that XRF on line monitoring of waterborne metals at trace levels is feasible for the influent and effluent of water treatment plants, and the effluent of wastewater treatment plants.

Enteroviruses, hepatitis A virus (HAV) and other enteric viruses can survive wastewater treatment processes, even after chlorination, and are found in the final effluents. These viruses can be detected by cell culture techniques with observations for cytopathic effect (CPE). Recently molecular detection of viral nucleic acids has been used. Most viruses found in wastewater are RNA viruses and RT-PCR is a rapid and sensitive method to detect these single-strand RNA enteric viruses. This methodology does not distinguish between infectious and non-infectious viruses. Viruses inactivated in the treatment process can be detected but do not pose a public health threat. Methods are needed to quickly distinguish the infectious viruses from inactivated viruses, both of which may be present in effluents. In this project we investigated the use of a method that combines cell culture and molecular detection. If a sample contains viruses that replicate in cell culture even without CPE, the proof of replication can be demonstrated by the detection of a replicative form (RF) in cell culture that is only present during replication of infectious RNA viruses.

The main objective of this research was to investigate the capabilities of three chemical oxidation processes as pretreatment technologies with the goal of making wastewaters containing persistent organic compounds amenable to biotreatment. The processes investigated are ozonation, ultraviolet radiation/ hydrogen peroxide (UV/H2O2) and Fenton reaction. The studies were focused on two organic compounds: Dichloro diethyl ether (DCDE) and methyl tertiary butyl ether (MTBE). Synthetic solutions, and a real groundwater and an industrial wastewater were used for experimentation. The experimental method involved oxidation of solutions of the target organic compounds at various percentages by the three oxidation processes. The pre-oxidized solutions of the organic compounds were subjected to biodegradation and toxicity studies. Four different respirometric tests (two Short-term, one Mid-term, and one Long-term) and a bench scale Sequencing Batch Reactor (SBR) test were used for full assessment of the effectiveness of the chemical oxidation processes. Activated sludge, as acclimated and non-acclimated to the organic compounds, was used as the test culture.

Thermal enrichment of coldwater streams by heated stormwater in summer months is often overlooked and even exacerbated by traditional management practices that typically account for flow moderation and pollutant removal only. Initiated in 1999, this study evaluated and identified innovative and traditional approaches to moderate this temperature impact by monitoring and analyzing the hydrologic and thermal regimes of an urban stormwater treatment system consisting of two traditional wet detention ponds and an enhanced natural wetland. Data analysis clearly shows temperature increases in the open detention ponds and the ability of the wetland to mitigate this thermal enrichment. Event-based thermal loading and temperature regime analysis indicated flow reduction via infiltration and effective vegetative cover in the wetland were the primary mechanisms for mitigating stormwater thermal enrichment. Using the concept of temperature equivalent, we also established the locations and strength of thermal enrichment areas. A heat transfer model was developed to simulate runoff temperature. Results indicated that rainfall characteristics, temperature difference between rainfall and the ground surface, and the runoff flow depth were the most important factors affecting runoff temperature.

The purpose of this book is to disseminate contemporary knowledge and practical experiences concerning problems and solutions related to urban hydrology and drainage. Although the main focus is on developing countries, the book draws from experiences in many other parts of the world. Based upon numerous practical examples and case studies, the book provides information to assist in the management, planning and engineering design processes. Urban Stormwater Management in Developing Countries covers a wide range of methods and approaches to improve the understanding and ability of local stakeholders to solve stormwater problems within the framework of integrated urban water management. As well as structural interventions, the book describes various non-structural approaches for flood mitigation and pollution control. This book encourages the reader to adopt an integrated approach towards stormwater management and considers the importance of institutional arrangements, participation of local stakeholders in planning, as well as aspects of financing and cost recovery. This comprehensive and topical book: Addresses the broad range of issues related to urban stormwater management with a specific focus on developing countries. Covers the main aspects of planning, design, operation and maintenance of urban drainage systems as well as socio-economic and institutional issues related to urban stormwater management. Presents structural and non-structural approaches for flood mitigation and pollution control within an integrated water resource management framework. Provides extensive examples and case studies of "e;best practice"e;. Contents Urbanisation and urban hydrology Impacts of flooding on society Integrated framework for stormwater management Institutional structures and policies Planning for urban stormwater management Approaches to urban drainage system design Ecological approaches to urban drainage system design Applications of computer models Operational performance and maintenance Flood mitigation and response strategies Participation and partnerships Economics and financing Full Contents List (27KB)

Numerous pharmaceutical substances and their metabolites have been identified in the aquatic environment. Due to their unique environmental fate and lack of appropriate biomonitoring techniques, the potential risk of these compounds to public and environmental health has largely been undetermined. Recent interest in quantifying pharmaceuticals in waste effluents and aquatic environments has identified the need to develop bioanalytical assays that will accurately reflect presence of these compounds. The goal of this research was to investigate the use of DNA microarrays as a bioanalytical tool for analysis of pharmaceutical contamination in re-use waters. Results from this study suggest that prototypic pharmaceutical contaminants target molecular events associated with pharmaceutical-induced gene induction and repression in exposed organisms. Gene expression profiles are subsequently evaluated as a means to discern pharmaceutical exposure. When fully developed, this bioanalytical approach will provide an efficient and robust method for screening pharmaceutical contaminants in reuse and other water matrices.

This book will give a comprehensive overview of modern analytical methods and will summarize novel single and hybrid methods to remove continuously emerging contaminants - micropollutants from the aqueous phase.

This report brings together results of previous and on-going EU projects with published data from both governmental sources and scientific literature and manufacturers data on production and usage of pharmaceuticals.

Newport Bay (Orange County, California) is listed by the California State Water Resources Control Board (SWRCB) as a water quality limited receiving water body because of sporadic exceedances of the fecal coliform water quality objectives for body contact recreation. Consistent with federal and state requirements, a Total Maximum Daily Load (TMDL) is being implemented in the watershed. The fecal coliform TMDL in Newport Bay is a phased approach for understanding and controlling the microbiological water quality in the to ensure the reasonable protection of the Bay?s beneficial uses. An important initial step within that TMDL was to assess the impairment of the body contact recreation beneficial use (REC-1) of Newport Bay receiving waters through characterizing the risk of illness associated with REC-1 exposure. A health risk assessment investigation was developed to characterize that risk. The health risk assessment investigation involved the integration of a population based model of disease transmission, a water quality modeling component necessary for estimating pathogen dose as part of the exposure assessment, and site-specific population use and receiving water data collection. The Water Environment Research Foundation funded the water quality modeling component of the health risk assessment investigation, which is the focus of this report. Also provided within this report is an overview of the health risk assessment methodology, a summary of the major findings from the risk assessment investigation, and a discussion of how the health risk methodology may be applied to other watersheds where impairment of the REC-1 beneficial use is in question. The major findings of the health risk assessment investigation indicated that (1) the risk of illness from REC-1 use in Newport Bay, estimated using two separate methods was generally below levels considered tolerable by US EPA, and (2) the reduction of controllable sources of pollution would not appreciably reduce the existing risk. Based on the collection of site-specific exposure data and the health risk characterization, it was determined that evaluating the impairment of the REC-1 beneficial use requires a more rigorous and comprehensive health based approach than that prescribed by the current regulations for recreational waters.

Farmers today are faced with an array of products that they can use to improve the fertility of their lands. Organic soil amendments such as biosolids, manures and, to a lesser extent, Municipal Solid Waste (MSW) composts are products that can be used to supplement or replace mineral fertilizers. Many farmers are aware of the benefits that organic products offer, especially in terms of improved crop yields, increased soil fertility, reduced fertilizer costs, and their overall contribution to sustainable agriculture. Concerns have been raised, however, regarding the safety of organic soil amendments. Depending on the type of product, these can include (but are not limited to) the accumulation of phosphorus and metals in soils, plant uptake of land-applied metals, the contamination of groundwater and soil with organic compounds, and potential health impacts from pathogens and viruses. Although many of these issues have been rigorously researched, data is often published in academic journals and textbooks, and is not necessarily accessible to the public. For all soil amendments, comparative information regarding risks, benefits, advantages, and disadvantages is not always readily available. Equally critical is the lack of accessible comparative data on soil amendment and mineral fertilizer characteristics and use.Recognizing the need to provide a comparison of these products, the Water Environment Research Foundation (WERF) commissioned this multi-year study of soil amendments, fertilizers and their uses. For the study, the project team performed a comprehensive literature survey, reviewing and compiling the results from nearly 500 documents (primarily from academic journals and texts). The study generally found that the relative risk to the environment from amendments and fertilizers varies by parameter and shows that known risks from each of the materials studied can be managed. Moreover, these manageable risks must be carefully weighed against the considerable benefits provided by the land application of amendments and fertilizers. This publication can also be purchased and downloaded via Pay Per View on Water Intelligence Online - click on the Pay Per View icon below

Employing an international and comparative analysis of international law as well as the domestic legal regimes of selected jurisdictions, i.e., China, South Africa and South Australia, Water Rights - An International and Comparative Study identifies the essential elements a well-structured water rights system, which ensures that the multiple functions of water resources are reasonably balanced, and the competing water needs are properly taken into consideration, and under which the economic, social and environmental values of water resources co-exist equitably in harmony. This book is the first to discuss water rights holistically, i.e., putting the three aspects of water rights (the property right of water resources, the human right to water and the environmental right to water) into a single, well-organised water rights system under the principle of sustainable development. Following the Introduction, Water Rights has six chapters. Chapter Two develops an analytical approach to be applied in the following four chapters. After the problems concerning water rights in China are identified, the three aspects of water rights both in international law and domestic water laws of South Africa and South Australia are discussed. In Chapter Six, principles and structure that should be employed for designing an ideal water rights system or improving and perfecting an existing one are recommended. With these recommendations, the definitions of water resources and the three aspects of water rights are analysed. Specific amendments to the China Water Law 2002 are proposed. Finally, this work concludes with explanations of the basis for the recommendations presented. This book will be a valuable reference for all those concerned with water rights, including lawyers, hydrologists and water resources managers.

Coagulation and Flocculation in Water and Wastewater Treatment provides a comprehensive account of coagulation and flocculation techniques and technologies in a single volume covering theoretical principles to practical applications. Thoroughly revised and updated since the 1st Edition it has been progressively modified and increased in scope to cater for the requirements of practitioners involved with water and wastewater treatment. A thorough gamut of treatment scenarios is attempted, including turbidity, color and organics removal, including the technical aspects of enhanced coagulation. The effects of temperature and ionic content are described as well as the removal of specific substances such as arsenic and phosphorus. Chemical phosphorus removal is dealt with in detail, Rapid mixing for efficient coagulant utilization, and flocculation are dealt with in specific chapters. Water treatment plant waste sludge disposal is dealt with in considerable detail, in an Appendix devoted to this subject. Invaluble for water scientists, engineers and students of this field, Coagulation and Flocculation in Water and Wastewater Treatment is a convenient reference handbook in the form of numerous examples and appended information.

In wastewater reclamation systems, microbiological monitoring is conducted to compare the effectiveness of biological treatment, filtration, and disinfection for removal of bacterial and viral indicators, enteric viruses, and protozoan pathogens. This project has six full-scale treatment facilities, sampled a minimum of four times over a year.

There is a pressing need for developing and testing a general set of theories in order to provide a confident basis for prediction of multiple stressor effects. Confident prediction is central to confident decision making in water pollution control. Consequently, WERF commissioned this study, which has as its goal to provide a study design based on good science that helps establish a general, conceptual approach to multiple stressors. The objectives addressed in this report are: (1) review and critique the existing body of knowledge for multiple stressors; (2) develop a searchable, annotated bibliography of multiple stressor research; and, (3) identify gaps in the body of knowledge. A rigorous, theoretical basis for the prediction of multiple stressor effects could not be developed from the literature on experimental studies of multiple stressor effects in aquatic ecosystems. Despite the wealth of observational data, the existence of several useful tools for interpretation of cause/effect relationships (including formal Stressor Identification methods), and the studies reviewed in this report, there are no tools that allow a confident, a priori, prediction of ecosystem response to multiple stressors. The current literature provides, at best, a series of site-specific glimpses of the response of ecological communities and ecosystems to multiple stressors. There is seldom, if ever, any reference to a more generalized model of multiple stressor effects apart from the discussion of the expectations regarding additivity versus synergism. Many articles that purport to be multiple stressor studies do not go beyond an inventory of the various stresses and upsets affecting the ecosystem, without attempting to assess the interactions among them.

Water resource management in the United States is evolving in the face of continuing challenges to protect water quality, provide adequate quantities of water for competing uses, and protect habitat and other natural resources. In many jurisdictions and agencies this evolution is increasingly leading toward adoption of watershed management. This approach is characterized by planning and decision making on a watershed scale, integration of a variety of competing water resource priorities and goals, cooperation of multiple stakeholders and governmental agencies, and increased levels of public participation. This report identifies the most promising watershed planning and management approaches from around the world; evaluates how they operate, their benefits and limitations; and assesses the degree to which these approaches could be successfully adapted to the U.S. context. Drawing on this international experience, the report is intended to inform policy makers and practitioners and to promote the implementation of integrated watershed management approaches that are most likely to succeed. This report: Provides a decision-making framework of watershed management efforts at all scales in the United States. Evaluates past U.S. watershed management experience and identifies key characteristics for success as well as major challenges and opportunities for improving the watershed approach. Summarizes and evaluates international case studies where innovative watershed management techniques have been used. Identifies ten key lessons for sustainable water management, including the role of water/wastewater utilities based on the experience of the international case study watersheds.

This report deals with whether the experience of odors, i.e., odors as sensations, from biosolids at wastewater treatment plants (WWTPs) causes illness. There exists no repository of information on the numbers of complainants with illness, their specific complaints, or the relationship between degree of exposure and complaints. Anecdotal reports nevertheless imply a pattern much like that associated with other industrial malodors. Any connection between odor and illness has received little note among the millions of articles in the medical literature. This state of affairs presumably exists because odors per se generate no objective signs of illness in otherwise healthy persons. However, malodors may exacerbate both symptoms and signs of illness in persons with certain chronic disorders, such as asthma and migraine. Vulnerability to such effects may vary considerably from person to person.

There is a pressing need for developing and testing a general set of theories in order to provide a confident basis for prediction of multiple stressor effects. Confident prediction is central to confident decision making in water pollution control. Consequently, WERF commissioned this study which has as its goal to provide a study design based on good science that helps establish a general, conceptual approach to multiple stressors. The objectives of the study are to develop a flexible and scientifically defensible conceptual model of the environmental effects of multiple stressors on river and stream ecosystems; develop a study design to test the conceptual model of multiple stressor effects; and, document the process used to arrive at the conceptual model. The multiple stressor conceptual model includes two main components: (1) a diagram that portrays the main features of the study team's understanding of how multiple stressors would interact and the nature of the effects; and (2) a series of three testable risk hypotheses. These two components follow the guidance provided by the U.S. EPA for ecological risk assessment. The proposed conceptual model encompasses the following key assumptions: interactions between the stressor and the ecosystem are dependant upon the existing baseline conditions; for each stressor/baseline combination there will theoretically be a functional and a structural response; effects on habitat are caused by structural or functional responses to stressors; and effects on habitat can cause structural or functional responses.

The presence of cationic pollutant metals in municipal wastewater effluent is a concern because stringent discharge requirements cannot always be met with conventional treatment methods. Attempts to improve metal removal are often unsuccessful because a significant fraction of the cationic metals are complexed by the synthetic chelating agent ethylenediamine tetraacetic acid (EDTA). To identify practical approaches for improving metal removal, an analytical method for measuring metal-EDTA complexes was used to survey metal speciation at a series of wastewater treatment plants. Following these analyses, bench-scale experiments were conducted. The survey data indicated that pollutant metal-EDTA complexes account for a significant fraction of the dissolved metals in wastewater. The bench-scale studies indicated that ferric chloride addition improves the removal of copper and zinc by approximately 20%. To test the results of the bench-scale experiments, a full-scale experiment was conducted by interrupting chemical addition at a municipal wastewater treatment plant that normally adds ferric chloride during primary treatment. Results indicated that ferric chloride addition had a slight impact on metal speciation but no effect on metals removal. The lack of an effect was attributed to changes in metal speciation that occurred during primary treatment irrespective of ferric chloride addition.