"Disinfection byproducts (DBP) are formed during the reaction of chemical disinfectants with natural organic material (NOM). DBPs are potential carcinogens and are regulated by the US Environmental Protection Agency (USEP A) under the Disinfectant/DBP (D/DBP) rule. High concentrations of NOM in drinking water sources used by Alaska's communities often result in the formation of DBPs during treatment. Since surface water sources in the Arctic are frozen for 6-9 months of the year, communities are often forced to store raw water for treatment during the winter or treat and store enough drinking water during the summer to last through the winter. The effects of long-term water storage practice and treatment technology on DBP formation was examined in the drinking water systems of 5 rural Alaskan communities. Results from this research suggest NOM escaping treatment is likely to react in the storage tank producing DBP concentrations well above the estimated DBP formation potential"--Leaf iii.
Drinking water disinfection has markedly reduced diseases causes by waterborne pathogenic microorganisms. However, an unintended consequence of disinfection and/or oxidation processes is the generation of disinfection byproducts (DBPs) which are formed from the reactions of disinfectants/oxidants with water matrix components. This volume of the Comprehensive Analytical Chemistry Handbook presents recent advances about the formation, identification, and quantification of inorganic and organic DBPs during oxidative processes. The book begins with a first chapter reviewing the most recent non-targeted screening approaches and workflows to characterize DBPs using low-, high-, and ultra-high-resolution mass spectrometry. The second chapter discusses the analysis of inorganic chloramines in waters using on-site and/or in-lab analytical methods. The third chapter provides an overview of the current knowledge about the mechanisms of chlorine dioxide reactions and byproducts formation. The fourth chapter presents some fundamental and practical aspects about ozonation processes in water treatment and provides an overview about ozone reaction mechanisms and byproducts formation. The fifth chapter focuses on the reactivity of halide ions, particularly bromide and iodide, with common oxidants and the role they play in determining the speciation of DBPs in treated waters. The chapter also presents strategies to mitigate the formation of DBPs during oxidation processes. Finally, the last chapter tackles the topic of DBPs formation during potable water reuse. It discusses the formation of DBPs of major concern in both memebrane-based and non-membrane-based potable water reuse treatment schemes. Researchers, water treatment specialists, and regulators will find in this book a valuable and compact resource on several key topics regarding the formation, identification, quantification, and mitigation of DBPs. Identification and quantification of known and unknown DBPs Formation of DBPs during different disinfection/oxidation processes DBPs of concern in new technologies and/or new applications of existing technologies in water treatment
Disinfection Byproducts in Drinking Water: Detection and Treatment presents cutting-edge research on how to understand the procedures, processes and considerations for detecting and treating disinfection by-products from drinking water, swimming pool water, and wastewater. The book begins with an overview of the different groups of Disinfection Byproducts (DBPs), such as: Trihalomethanes (THM), Halo acetic acids, and Haloacetonitrile (HAN). This coverage is quickly followed by a clear and rigorous exposition of the latest methods and technologies for the characterization, occurrence, formation, transformation and removal of DBPs in drinking water. Other chapters focus on ultraviolet-visible spectroscopy, electron spin resonance, and gas chromatography-mass spectrometry. Researchers will find a valuable resource to a breath of topics for DBP detection and treatment, including various recent techniques, such as microfiltration, nanofiltration membrane and nanotechnology. Explains the latest research in detection, treatment processes and remediation technologies Includes sampling, analytical and characterization methods and approaches Covers cutting-edge research, including membrane based technologies, nanotechnology treatment technologies and bioremediation treatment technologies Provides background information regarding contamination sources
The EPA has established regulations which classify four types of disinfection byproducts - TTHMs, haloacetic acids, bromate, and chlorite - and requires public water systems limit these byproducts to specific levels. Most of the information required to comply with these standards is either scattered throughout the literature or derived from confere
Covering the latest developments in themes related to water disinfection by-products, this book brings the academic and industry researchers right up to date.
Disinfection of potable water is one of the great public health victories of the twentieth century, responsible for the avoidance of millions of deaths due to waterborne illness. However, application of disinfectants, typically chemical oxidants, leads to formation of hundreds of trace contaminants, often carcinogens, and consumption of chlorinated water has been epidemiologically linked to bladder cancer and certain birth defects. Eleven of these compounds are federally regulated in drinking water, but certain non-regulated disinfection byproducts (DBPs) are orders of magnitude more toxic than currently regulated compounds. Two specific DBPs, chloropicrin and N-nitrosodimethylamine (NDMA), are especially genotoxic, and are associated with nitrogen input into drinking water supplies. Wastewater-impacted drinking water and recycled wastewater are enriched in the precursors of these compounds, and their formation during potable water treatment is likely to grow, as wastewater increasingly contributes to the water supply. This thesis focuses on applying the tools of environmental organic chemistry to identify the chemical precursors and formation mechanisms of these compounds, leading to strategies for their control during water treatment. In particular, ozonation of primary and secondary amine compounds, leading to formation of nitro compound intermediates, was found be responsible for chloropicrin formation during water treatment. Secondary N-methylamines and primary amines geminal to facile leaving groups were particularly potent precursors, forming chloropicrin at up to 50% yield when exposed to ozone followed by chlorine. Based on this predominant formation pathway, chloropicrin precursors may be oxidized upstream of ozone addition to prevent chloropicrin formation. Strategies for controlling NDMA formation, a major concern during wastewater recycling, were developed based on an understanding of the chemical composition of NDMA precursors, and chloramines, the primary disinfectant applied during wastewater reuse. Minor modifications to wastewater recycling operations, in particular switching from low-pressure to medium-pressure mercury lamps for ultraviolet light treatment, and minor adjustments in the application of chloramines, were shown to dramatically reduce NDMA concentrations in final effluent. Finally, the effluent from a new, all-anaerobic wastewater treatment system was demonstrated to more efficiently remove trace contaminants and DBP precursors than conventional aerobic treatment, suggesting that this energy-saving technology may also be more suitable for water reuse than conventional treatment. These findings facilitate reducing the chronic health risk associated with consumption of (intentionally or unintentionally) recycled wastewater.
Disinfection By-Products in Water Treatment describes new government regulations related to disinfection by-products. It explains the formation of microorganism by-products during water treatment and the methods employed to control them. The book includes several chapters on chlorine by-products and discusses techniques for the removal of chloroform from drinking water. It also describes gamma radiation techniques for removing microorganic by-product precursors from natural waters and the removal of bromate from drinking water.
The advent of drinking water disinfection to inactivate pathogens was a significant public health achievement. However, disinfectants react with dissolved organics to form disinfection byproducts (DBPs), which have been associated with bladder cancer, colorectal cancer, and adverse reproductive outcomes. After 50 years of research, it remains unclear which DBP classes drive the toxicity of disinfected drinking water. Globally, trihalomethanes (THMs) are the most commonly regulated DBP class. THMs are used as a surrogate for DBP exposure based on the assumption that they are representative of the overall DBP mixture. Two recent trends challenge this assumption: 1) the identification of hundreds of DBP species with precursors and formation pathways distinct from THMs, and 2) an increase in potable reuse of reclaimed municipal wastewater, which contains precursors that promote the formation of nitrogen-containing DBP classes (N-DBPs). Although N-DBPs are unregulated in most countries, in vitro and in vivo toxicity studies indicate they are more toxic than THMs. The four studies comprising this dissertation demonstrate that US and global DBP policy may not lead to treatment choices that effectively minimize health risk, particularly for the large population that relies on wastewater-impacted drinking water without advanced treatment. The first two studies utilized a pilot-scale system to evaluate the potential of several disinfection strategies (one existing, one novel) to minimize DBP-associated toxicity while meeting regulatory limits for pathogens and DBPs in reclaimed wastewater. The first study focused on tradeoffs between regulated and unregulated DBP formation with chlorine-chloramine disinfection. Pre-oxidation with free chlorine is effective for inactivating viruses and reducing the formation of N-Nitrosodimethylamine (NDMA), which is being considered for regulation in the US. Compared to chlorine, chloramines mitigate the formation of THMs and haloacetic acids (HAAs), which are regulated in the US. A minimal pre-chlorine contact time achieved inactivation of the virus indicator MS2 while maintaining THM and HAA concentrations below regulatory limits. A longer pre-chlorination contact time was required to reduce NDMA to target levels; however, this increased the estimated toxicity of the DBP mixture, primarily due to the formation of haloacetonitriles (HANs), an unregulated N-DBP class. The second study introduces a novel disinfection method, distributed chorine injection, to reduce NDMA formation during break-point chlorination. The efficacy of this method was demonstrated at pilot-scale, and the hypothesized mechanism was proven with kinetic modeling and bench experiments. Distributed chlorine injection is a low-cost strategy for utilities to meet low NDMA limits without increasing halogenated DBP formation. The final two studies addressed whether THMs are an effective surrogate for unregulated DBP classes. The first investigated this question in the context of treatment and infrastructure practices in low- and rising-middle income countries through a case study in Rajasthan, India. Most of the water sources were impacted by wastewater due to minimal sanitation infrastructure. The low to moderate levels of THMs measured were not indicative of high concentrations of unregulated DBPs in many drinking waters. The concentrations of toxic, unregulated DBP classes in the largest water system resembled those measured in reclaimed wastewater for nonpotable reuse. HANs were again the dominant contributor to estimated toxicity. Thus, the final study was designed to conclusively determine whether THMs are an effective surrogate for HANs. Multiple statistical models were developed using a large database of DBP concentrations measured in distribution systems of ~250 US public water systems. Multilevel/hierarchical regression models identified substantial systematic variance in the HAN:THM ratio between water systems and within distribution systems. A portion of the variance was attributed to factors such as source water type, disinfectant sequence, distribution system retention time, as well as seasonal effects on surface water. A risk ratio analysis indicated that using THMs as a surrogate for HAN exposure introduces significant classification bias. Overall, these findings underscore the need to identify the toxicity drivers in disinfected waters so that treatment systems can be designed to target those DBP classes. Furthermore, a new global policy paradigm should account for local factors influencing DBP speciation and holistically address the risk posed by complex contaminant mixtures in drinking water.
It is 25 years since the discovery that potentially harmful chemical by-products are generated by the disinfection of drinking water. Since then, disinfection by-products (DBPs) have had a significant impact on drinking water standards, treatment processes and monitoring. Regulators and water suppliers must find a balance between the need to prevent microbial contamination, and the desire to control the levels of DBPs in the water we drink. Disinfection By-Products in Drinking Water: Current Issues brings together contributions from regulators, researchers and water suppliers from Europe and North America to discuss the current situation and identify the main issues associated with reaching a cost-effective balance between microbial and chemical risks. Overviews of the latest research are presented alongside case studies of practical approaches taken by water companies and regulators on both sides of the Atlantic. Contributions are grouped into sections covering: DBP formation and occurrence; advances in analysis and monitoring; standards and regulation; balancing chemical and microbial risk; and control methods for DBPs. A final chapter pulls these strands together to provide a view of the way forward. Disinfection By-Products in Drinking Water: Current Issues is a unique collection of the views of key people, and as such will be essential reading for all those with an interest in this complex problem.
