Download or read book The Formation of N nitrosodimethylamine NDMA from Reaction of Monochloramine with Natural Organic Matter written by Zhuo Chen and published by . This book was released on 2006 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Formation Studies on N nitrosodimethylamine NDMA in Natural Waters written by Xianghua Luo and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: N-nitrosodimethylamine (NDMA) is a chloramines disinfection by-product and probable carcinogen to human. The California state established a 10 ng/L action level for NDMA in drinking water. Analytical method of NDMA in waters at the trace level was developed using gas chromatography/mass spectrum with chemical ionization in the mode of selected ion storage coupled with solid phase extraction. It was found that 4 utilities in Missouri using monochloramine as disinfectant had NDMA higher than 10 ng/L in drinking water. Natural organic matter (NOM), especially the hydrophilic fraction of the NOM, was found to be a predominant NDMA precursors. Basic conditions and bromide ions favor NDMA formation in natural waters. The findings reported in this dissertation provide data on NDMA occurrences in drinking water and natural waters in Missouri. The results provide valuable information about NDMA precursors in natural waters and this information could be used in the further study of mitigating NDMA formation or removing NDMA precursors in drinking water utilities. The results on factors affecting on NDMA formation provide more information for water utilities to determine operation conditions to reduce and control NDMA formation.
Download or read book Quantification of the Reactivity of Nitrosamine Precursors written by Yang Zhao and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigations Into the Occurrence Formation and Fate of N nitrosodimethylamine NDMA in Air and Water written by Jinwei Zhang and published by . This book was released on 2016 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: N-nitrosodimethylamine (NDMA), a probable human carcinogen, has been found in clouds and fogs at concentration up to 500 ng/L and in drinking water as a disinfection by-product. NDMA exposure to the general public is not well understood because of knowledge gaps in terms of occurrence, formation and fate - both in air and water. The goal of this dissertation was to contribute to closing these knowledge gaps on potential human NDMA exposure through contributions to atmospheric measurements and fate as well as aqueous formation processes. Novel, sensitive methods of measuring NDMA in air were developed based on Solid Phase Extraction (SPE) and Solid Phase Microextraction (SPME) coupled to Gas Chromatography-Mass Spectrometry (GC-MS). The two measuring techniques were evaluated in laboratory experiments. SPE-GC-MS was applicable in ambient air sampling and NDMA in ambient air was found in the 0.1-13.0 ng/m3 range. NDMA photolysis, the main degradation atmospheric pathway, was studied in the atmospheric aqueous phase. Water soluble organic carbon (WSOC) was found to have more impact than inorganic species on NDMA photolysis by competing with NDMA for photons and therefore could substantially increase the NDMA lifetime in the atmosphere. The optical properties of atmospheric WSOC were investigated in aerosol, fog and cloud samples and showed WSOC from atmospheric aerosols has a higher mass absorption efficiency (MAE) than organic matter in fog and cloud water, resulting from a different composition, especially in regards to volatile species, that are not very absorbing but abundant in fogs and clouds. NDMA formation kinetics during chloramination were studied in aqueous samples including wastewater, surface water and ground water, at two monochloramine concentrations. A simple second order NDMA formation model was developed using measured NDMA and monochloramine concentrations at select reaction times. The model fitted the NDMA formation well (R2 >0.88) in all water matrices. The proposed model was then optimized and applied to fit the data of NDMA formation from natural organic matter (NOM) and model precursors in previously studies. By determining the rate constants, the model was able to describe the effect of water conditions such as DOC and pH on NDMA formation.
Download or read book Potential N Nitrosodimethylamine NDMA Formation from Water Treatment Polymers written by Piti Piyachaturawat and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: N-Nitrosodimethylamine (commonly known as NDMA) is a probable human carcinogen that has been recognized as an emerging drinking water contaminant in recent years. Previous studies have shown that certain N-containing organic compounds may form NDMA in reaction with chlorine or monochloramine and the NDMA yield is affected by the structure of the organic-N compounds, water conditions and treatment parameters. Many amine-based water treatment polymers contain organic-N functional groups and thus have been suspected as potential NDMA precursors in water treatment systems. The purpose of this research was to systematically assess the potential NDMA formation from different structural types of water treatment polymers in reactions with various oxidants and probe the possible factors that influence the NDMA formation. Robust analytical methods for detection of NDMA and the well-known NDMA precursor dimethylamine (DMA) in the reaction samples were established. The cationic polyacrylamide (cationic PAMS), aminomethylated polyacrylamide (Mannich), poly-diallyldimethylammonium chloride (polyDADMAC) and polyamine polymers were evaluated in reactions with nitrite, free chlorine, monochloramine or chlorine dioxide in aqueous solutions at circumneutral pH and room temperature conditions. This study employed high dosages of polymer and oxidant and long reaction time in order to assess the maximum potential to form NDMA. A range of operational parameters that may affect the above reactions were also evaluated.
Download or read book Prevention of the Formation of N nitrosodimethylamine NDMA During Wastewater Chlorination written by William Armistead Mitch and published by . This book was released on 2003 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Understanding N nitrosodimethylamine Formation in Water written by Huong Thu Pham and published by . This book was released on 2017 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: The formation of N-nitrosodimethylamine (NDMA) in drinking water systems is a concern because of its potential carcinogenicity and occurrence at toxicologically relevant levels. The postulated mechanism for NDMA formation involves a substitution between dichloramine and amine-based precursors to form an unsymmetrical dimethylhydrazine (UDMH), which is then oxidized by ground-state molecular oxygen to form NDMA. However, this latter reaction is spin forbidden, thus likely occurs at a slow rate. It is hypothesized that the reaction between monochloramine and hydroxylamine (a nitrification product) may form an intermediate, which is involved in the NDMA formation pathway. This intermediate may also be generated from dichloramine decay, in the absence of hydroxylamine. In this study, a series of batch kinetic experiments were conducted to investigate the decomposition of chloramine species at pH 8.0 to 10.0 and the concomitant formation of NDMA. Chloramine species were quantified using UV/Vis spectroscopy (Direct UV) and colorimetric methods (Hach) and compared to simulations from the unified chloramine model. NDMA was quantified using GC-MS following liquid-liquid extraction. The model captured the decay of monochloramine and dichloramine adequately, with the exception of monochloramine at pH 10.0, possibly due to an interference from a previously reported unidentified chloramine decomposition compound (UC1). NDMA formation was pH dependent with the maximum yields at pH 9.0 and the fastest kinetics at pH 10.0. A second unidentified compound (UC2), with a mass spectrum identified as UDMH, was detected only at pH 9.0 and 10.0 in batch reactors with DMA and dichloramine. Importantly, NDMA formation appeared to be insensitive to the presence or absence of UC2, suggesting UC2 was not involved in NDMA formation. Hydroxylamine accelerates the decomposition of monochloramine. The reaction between DMA and hydroxylamine formed a third unidentified compound (UC3), preliminarily identified as acetoxime, which was not observed in the presence of monochloramine. Upon addition of hydroxylamine, NDMA yields decreased by more than half in batch reactors with DMA and monochloramine. On balance, the findings suggest the existence of a NDMA formation pathway that may not involve UDMH, and points to the need for studies with scavengers and donors of short-lived species from chloramine decay.
Download or read book Effect of Preformed Chloramines and Chlorine to Ammonia Ratio on the Formation of N nitrosodimethylamine NDMA in TRWD East Texas Raw Water Delivery System written by Khidir Hamad and published by . This book was released on 2015 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tarrant Regional Water District (TRWD) pumps untreated raw water from Richland Chambers and Cedar Creek reservoirs in East Texas to provide water to several customer cities including Arlington and Fort Worth. TRWD adds chloramines to the pipeline to combat biofilm growth, that reduces pipeline capacity and increases pumping costs, and to control zebra mussels, that clog intake structure screens and the pump wet wells. However, addition of chloramines leads to the formation of Nnitrosodimethylamine (NDMA), a potent carcinogen, by reaction of chloramines with nitrogenous organic precursors possibly present in the raw water. NDMA formation presents a challenge to TRWD because potential regulation of NDMA and other nitrosamines will force TRWD and other utilities alike to seek treatment options. Because post treatment removal of NDMA is ineffective and expensive, the best strategy is to optimize conditions to minimize NDMA formation and to eliminate nitrogenous NDMA precursors in the system. This research examines the effect of preformed chloramines and chlorine to ammonia mass ratio on NDMA formation in the District's current and future pipelines.
Download or read book Nitrosamines and Related N nitroso Compounds written by Richard N. Loeppky and published by . This book was released on 1994 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigates the compound formation, bioactivation, and detoxification of the N-nitroso group of compounds, which increasingly appears to be implicated in human carcinogenesis. The topics include exposure, formation, and blocking; nitric oxide; nitrosamine; toxic, mutagenic, and carcinogenic effects; and reactive intermediates. The 45 papers largely report on research rather than review the literature. The symposium that occasioned them was in Washington, DC, in August 1992. Annotation copyright by Book News, Inc., Portland, OR
Download or read book Advanced Oxidation Processes for Water Treatment written by Mihaela I. Stefan and published by IWA Publishing. This book was released on 2017-09-15 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Oxidation Processes (AOPs) rely on the efficient generation of reactive radical species and are increasingly attractive options for water remediation from a wide variety of organic micropollutants of human health and/or environmental concern. Advanced Oxidation Processes for Water Treatment covers the key advanced oxidation processes developed for chemical contaminant destruction in polluted water sources, some of which have been implemented successfully at water treatment plants around the world. The book is structured in two sections; the first part is dedicated to the most relevant AOPs, whereas the topics covered in the second section include the photochemistry of chemical contaminants in the aquatic environment, advanced water treatment for water reuse, implementation of advanced treatment processes for drinking water production at a state-of-the art water treatment plant in Europe, advanced treatment of municipal and industrial wastewater, and green technologies for water remediation. The advanced oxidation processes discussed in the book cover the following aspects: - Process principles including the most recent scientific findings and interpretation. - Classes of compounds suitable to AOP treatment and examples of reaction mechanisms. - Chemical and photochemical degradation kinetics and modelling. - Water quality impact on process performance and practical considerations on process parameter selection criteria. - Process limitations and byproduct formation and strategies to mitigate any potential adverse effects on the treated water quality. - AOP equipment design and economics considerations. - Research studies and outcomes. - Case studies relevant to process implementation to water treatment. - Commercial applications. - Future research needs. Advanced Oxidation Processes for Water Treatment presents the most recent scientific and technological achievements in process understanding and implementation, and addresses to anyone interested in water remediation, including water industry professionals, consulting engineers, regulators, academics, students. Editor: Mihaela I. Stefan - Trojan Technologies - Canada
Download or read book Toxicological Profile for N nitrosodimethylamine written by and published by . This book was released on 1989 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Isotope Effects In Chemistry and Biology written by Amnon Kohen and published by CRC Press. This book was released on 2005-11-01 with total page 1092 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of isotope effects has expanded exponentially in the last decade, and researchers are finding isotopes increasingly useful in their studies. Bringing literature on the subject up to date, Isotope Effects in Chemistry and Biology covers current principles, methods, and a broad range of applications of isotope effects in the physical, biolo
Download or read book NDMA Formation During Drinking Water Treatment Veterinary Antibiotics as Precursors the Effect of Natural Organic Matter and the Significance of Treatment Practices written by Shannon Roback and published by . This book was released on 2015 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrosodimethylamine (NDMA) is a nitrosated amine that has been associated with a 10-5 increase in lifetime cancer risk at the ng/L level. NDMA may be formed from a variety of anthropogenic amine precursors during drinking water treatment utilizing chloramines as a disinfectant. In this dissertation, ten veterinary antibiotics were tested for their ability to form NDMA. The antibiotics were tested at different pH, temperature, chlorine to ammonia weight ratio (Cl2/NH3) and time to determine the impact of these factors on formation. Molar conversions ranged from 0.04 to 4.9 percent, with antibiotics containing more than one dimethylamine (DMA) functional group forming significantly more NDMA. The highest formation for most of the compounds was seen near pH 8.4. The effect of Cl2/NH3 ratio, temperature, and hold time was somewhat varied for each chemical, suggesting that the effects of these parameters were compound-specific. This suggests that large-scale farming run-off may be a new source NDMA precursors. NDMA formation is slowed by the presence of natural organic matter (NOM). It is not currently known which components of NOM are responsible for the reduction in NDMA formation. In this dissertation, water containing NOM was fractionated into different MW size groups or separated based on polarity. The high molecular weight NOM fractions (> 10 kDa), polar and charged components were shown to be the most effective in reducing the amount of NDMA formed. Some precursors have high sorption coefficients to NOM, which is the likely mechanism for reduction of NDMA formation from these compounds. Lastly, NDMA formation can be highly impacted by numerous factors relevant to drinking water treatment. In this dissertation, water samples and treatment plant data were collected from approximately 20 drinking water treatment plants in the U.S. and Canada over 2 years. Linear mixed effects models with random intercepts, which account for variability between treatment plants, were used to assess variable significance and create predictive equations. UV254 concentration in the plant influent, sucralose concentration, polyDADMAC concentration, pre-chlorination time, Cl2/NH3 ratio, use of GAC, water pH, and biofiltration were associated with NDMA concentration in the distribution system.
Download or read book Drinking Water Distribution Systems written by National Research Council and published by National Academies Press. This book was released on 2007-01-22 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: Protecting and maintaining water distributions systems is crucial to ensuring high quality drinking water. Distribution systems-consisting of pipes, pumps, valves, storage tanks, reservoirs, meters, fittings, and other hydraulic appurtenances-carry drinking water from a centralized treatment plant or well supplies to consumers' taps. Spanning almost 1 million miles in the United States, distribution systems represent the vast majority of physical infrastructure for water supplies, and thus constitute the primary management challenge from both an operational and public health standpoint. Recent data on waterborne disease outbreaks suggest that distribution systems remain a source of contamination that has yet to be fully addressed. This report evaluates approaches for risk characterization and recent data, and it identifies a variety of strategies that could be considered to reduce the risks posed by water-quality deteriorating events in distribution systems. Particular attention is given to backflow events via cross connections, the potential for contamination of the distribution system during construction and repair activities, maintenance of storage facilities, and the role of premise plumbing in public health risk. The report also identifies advances in detection, monitoring and modeling, analytical methods, and research and development opportunities that will enable the water supply industry to further reduce risks associated with drinking water distribution systems.
Download or read book Analysis and Formation of Disinfection Byproducts in Drinking Water written by and published by Elsevier. This book was released on 2021-04-01 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Download or read book The Llobregat written by Sergi Sabater and published by Springer. This book was released on 2012-06-02 with total page 381 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Llobregat belongs to the most thoroughly studied rivers in Europe and is a paradigm of the confluence of human and natural disturbances in a single basin. Because of its location in a very densely populated region and its Mediterranean character, the Llobregat supports a mixture of irregular flow, water abstraction, excess nutrients, mining debris, and a wide array of pollutants. The aquatic organisms strive to survive in a dramatically changing river that passes through a succession of dams, weirs and channels. The long-term river monitoring as well as the research that has been carried out in the river for a long time have provided an extensive knowledge of these disturbances and their effects on the biological communities. This book highlights the available information, with emphasis on the hydrological, chemical and biological elements interspersed in the river. Experts in the field discuss the main nutrient patterns and pollutant occurrence and the responses of the biological quality elements as well as the river ecosystem to the overall natural and man-made influences.
Download or read book Active Oxygen in Chemistry written by Christopher S. Foote and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: Taking an interdisciplinary approach, this book and its counterpart, Active Oxygen in Biochemistry, explore the active research area of the chemistry and biochemistry of oxygen. Complementary but independent, the two volumes integrate subject areas including medicine, biology, chemistry, engineering, and environmental studies.
