Download or read book Studies on the Influence of Chemical Disinfection Ultraviolet Irradiation and Pipe Matrix on Biofilm Composition in Drinking Water Distribution Systems written by Fernando M. G. Matias and published by . This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Influence of Biofilm on Disinfection Byproducts Formation and Decay in a Simulated Water Distribution System written by Zhikang Wang and published by . This book was released on 2013 with total page 283 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since biofilm has been implicated in the deterioration water quality and the increase of public health risks, various efforts have been made to minimize biofilm regrowth in drinking water distribution systems. Although traditional water treatment processes can greatly remove a large fraction of disinfection by-products (DBPs) precursors, a small portion of natural organic matter (NOM) may still enter water distribution systems. Untreated NOM can serve as nutrients for biofilm growth while also consuming maintained disinfection residuals, which can result in microbial contamination in drinking water. To suppress biofilm formation, water utilities maintain disinfectant residuals for the distribution system. However, upon disinfectant addition, toxic DBPs are inevitably produced. Biofilm and its secreted extracellular polymeric substances (EPS) produce toxic DBPs, due to the very similar chemical composition compared to traditional investigated DBP precursors. This research investigated the role of biofilm on DBP formation and decay in simulated drinking water distribution systems with four objectives. The first objective was to investigate the influence of chemical composition and quantity of bacterial EPS on the biosorption of NOM in drinking water. Results indicated that both protein and polysaccharide based EPS adsorbed existing NOM. Biosorption capacity was mainly determined by divalent ion (Ca2+ and Mg2+) concentrations. Mechanistically, the presence of a diffuse electrical double layer inhibited NOM biosorption by potential energy barriers, however, presence of divalent ions in the aquatic environment enhanced biosorption processes, permitting functional group interactions between EPS and NOM. In addition, hydrophobic interactions, EPS characteristics and quantity can also be used to explain biosorption results. Bridging between hydrophilic carboxyl groups on alginate EPS and NOM appeared to be the dominant form of biosorption, while hydrophobic interactions enhanced biosorption for protein-based EPS. The second and third objectives of this study were to investigate the role of biofilm EPS on the formation of both carbonaceous DBPs (C-DBPs) and nitrogenous DBPs (N-DBPs). DBP yield (formation potential) tests of both bacterial culture and extracted EPS indicated that the chemical composition and quality of EPS played a critical role for DBP formation. In general, protein based EPS possessed higher DBP yields compared to polysaccharide based EPS, especially for N-DBPs. To further determine the relative contribution of each biomolecule in EPS to DBP formation and speciation, detailed chemical compositions of biomolecules in EPS (amino acids, polysaccharide monomers, and fatty acids) from both pure culture and mixed species biofilm isolated from a water utility were analyzed. DBP yield results from both extracted EPS and EPS surrogates (amino acids and polysaccharide monomers) indicated that proteins in EPS have a greater impact on DBP formation, where amino acids containing unsaturated organic carbon or conjugated bonds in R-group produced higher amount of DBPs. However, DBP yields of polysaccharide monomers were lower than those of tested amino acids groups and the DBP yields were not significantly influenced by their chemical structures. The last objective of this study was to understand the influence of biofilm on DBP formation and decay in a simulated water distribution system using lab scale annular reactors. For Cl2 disinfection at 0.5 mg L-1 Cl2 residual concentration, no obvious DBP formation was observed. This was mainly due to the combination of low DBP formation, DBP volatilization, and biodegradation. However, when high Cl2 residuals were maintained, the formations of both C-DBPs and N-DBPs increased dramatically beyond the DBP formation potential of the feed solution. This suggests higher Cl2 residual not only reacted with humic acid (HA) in feed solution but also reacted with biofilm and produced extra DBPs, especially the high formation of N-DBPs (haloacetonitriles). For NH2Cl disinfection, the DBP levels were much lower than those of Cl2 disinfection and differences in DBP formation were not significant under different NH2Cl residual concentrations. Combined results suggested that biofilm can impact both C-DBP and N-DBP formation and decay in water distribution systems, where biomolecules in EPS affect DBP speciation.

Download or read book Control of Biofilm Growth in Drinking Water Distribution Systems written by and published by . This book was released on 1992 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Identification and Correlation of Disinfection Byproducts and Total Organic Halogen Precursors in a Biofilm Matrix written by Mohd Yahya Khan and published by . This book was released on 2014 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: Disinfection by-products (DBP) formation in drinking water systems is a persistent issue for water utilities. Although DBP formation is complex due to the multitude of chemical and biological interactions that occur, unremoved natural organic matter (NOM) entering the water distribution system is generally regarded as the primary precursor for DBP formation. In addition, NOM also provides nutrients that support microbial growth and persistent biofilm formation. Biofilm formation is widespread within the water distribution system due to the continuous influx of unremoved NOM. Biofilm and its associated extracellular polymeric substances (EPS) provide a dynamic repository for organic matter accumulation, and can act as a DBP precursor. Trihalomethanes (THMs) and Haloacetic acids (HAAs) represent the major classes of regulated DBPs, yet there are several others that form due to the complex interaction between the organic matter and the disinfectants. The unknown total organic halogens (UTOX) is believed to contain toxicologically vital compounds. Until recently, there have been no reliable studies analyzing the relative contributions of biofilm and its associated DBP precursors to DBP formation and speciation, and how these different precursors contribute to the total organic halogen (TOX) formation. This work seeks to abridge this knowledge gap by analyzing the DBP formation from chlorination of biofilms in simulated water distribution systems. The results of this study provide critical information about potential contributions of biofilms to the formation of DBPs and UTOX in the distribution systems and can help water utilities better control the levels of both regulated and unregulated DBPs while at the same time reducing health risks associated with DBPs. To help elucidate this interaction, heterotrophic plate counting (HPC) of bacterial colonies in different pipe materials under different chlorine residuals were conducted. Additionally, DBP and TOX formation tests were conducted and correlated with parallel factor analysis (PARAFAC) of fluorescent dissolved organic carbons. The obtained results suggest that depending on the pipe material, the accumulation of organic matter in biofilm matrix contributes significantly towards DBP formation. Corrosion of iron pipes provides not only more opportunity for growth of biofilm, but also increased adsorption sites for humic substances, both of which lead to increased DBP and UTOX formation. Overall, strong evidence of biofilm contribution to DBP formation in drinking water distribution systems suggests that water utilities need to carefully consider biofilm eradication methods to minimize the subsequent formation of toxic compounds.

Download or read book Long Term Effects of Disinfection Changes on Water Quality written by John E. Dyksen and published by American Water Works Association. This book was released on 2007 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: In response to many U.S. water utilities that are considering changing disinfectants from chlorine to alternative disinfectants, this research has been undertaken to gain knowledge of long-term effects.

Download or read book Impact of Ultraviolet Disinfection on Biofilm Growth in a Model Distribution System written by Nicole Lea Celine Giese and published by Ann Arbor, Mich. : University Microfilms International. This book was released on 2002 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Impact of Distribution System Water Quality on Disinfection Efficacy written by Hé́lène Baribeau and published by American Water Works Association. This book was released on 2005 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Assesses the impact of dynamic water quality conditions in the distribution system on the inactivation of microorganisms in bulk water. Addresses questions about the usefulness of maintaining a secondary residual and the target level to be maintained. Bridges research related to distribution system water quality with that of microbial inactivation.

Download or read book Microbial Quality of Water Supply in Distribution Systems written by Edwin E. Geldreich and published by CRC Press. This book was released on 2020-07-26 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hidden problems, buried deep in the pipe networks of water distribution systems, are very serious potential threats to water quality. Microbial Quality of Water Supply in Distribution Systems outlines the processes and issues related to the degradation of water quality upon passage through networks of pipes, storage reservoirs, and standpipes on its way to the consumer. The risks associated with biofilm accumulation, bacteria, and other contaminants are discussed in great detail. In addition to its excellent microbiological coverage of organisms in drinking water and biofilms in distribution systems, Microbial Quality of Water Supply in Distribution Systems provides clear treatments of the technical and public communication issues most commonly affecting the quality of water and water supply systems. The inclusion of numerous case histories in this new book makes it a complete reference source for anyone concerned with water quality and water distribution systems.

Download or read book Control of Biofilm Growth in Drinking Water Distribution Systems written by DIANE Publishing Company and published by DIANE Publishing. This book was released on 1994-05 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes the types of organisms often present in drinking water distribution system biofilms, how biofilms are established and grow, the public health problems associated with having biofilms in the distribution system, and tools that water treatment personnel can use to help control biofilm growth. Glossary of terms, and list of additional resources. Charts, tables and photos.

Download or read book Disinfection By Products in Drinking Water written by M Fielding and published by Elsevier. This book was released on 1999-01-01 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume brings together contributors from water regulators, and water suppliers in Europe and North America to discuss the main issues associated with reaching a cost-effective balance between microbial and chemical risks. Overviews of research are presented alongside illuminating case studies of the practical approaches taken by water companies and regulators on both sides of the Atlantic.

Download or read book Impact of UV Disinfection on Biological Stability written by G. Gagnon and published by International Water Assn. This book was released on 2005-01-01 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall objective of the research was to evalu

Download or read book Ultraviolet disinfection guidance manual written by and published by DIANE Publishing. This book was released on 2003 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Prevention and Monitoring of Biofilm Formation in Drinking Water Distribution Systems written by Fahimeh Bimakr and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated] Biofilm formation in drinking water distribution systems (DWDSs) causes detrimental impacts on water quality and infrastructure. Biofilms can also act as a reservoir for pathogens, and are thus of public health concern. To discourage biofilm growth in DWDSs, antimicrobial agents (disinfectants) including chlorine, chloramines and ozone are used. However, these chemicals produce harmful disinfection by-products, many of which are toxic and carcinogenic, and hence their formation should be minimised. The challenge to maintain appropriate disinfection and to avoid unwanted effects of biofilm formation in DWDSs requires the development of new technologies for efficient disinfection and microbial control. Biofilm formation is affected by the type of pipe wall material, especially its surface characteristics, including roughness, surface energy and biological affinity. Pipe materials may also release substances that enhance or inhibit biofilm formation, and so influence the presence and persistence of microbial pathogens. A number of nanomaterials having antimicrobial properties have been proposed for use in water treatment. Moreover, microstructured surfaces and other surface coatings have also been reported to inhibit biofilm formation. In this study a number of polymers of different hydrophobicity including high density polyethylene (HDPE), polytetrafluoroethylene (PTFE) and nylon, with and without embedded copper, as well as a nanomaterial (carbon nanotubes) and marine paint (Hempel X3) were tested for their effects on biofilm formation in a laboratory scale pipe rig containing water from a water supply reservoir (Mundaring Weir, Perth, Western Australia), and compared with the traditional pipe materials stainless steel and concrete. Microbial growth on the tested materials was measured by counting DAPI-stained cells using epifluorscence microscopy, flow cytometry, heterotrophic plate agar, and an ATP assay for measuring cellular activity. Biofouling on all tested materials was detected using all four methods (ATP assay, epifluorescence microscopy, flow cytometry and colony counting) as rapidly as 1 h following installation of the material into the laboratory pipe rig. The results showed that none of the tested materials or coatings showed superior performance in preventing biofilm formation relative to stainless steel or concrete.

Download or read book Coliforms in Distribution Systems written by Graham A. Gagnon and published by American Water Works Association. This book was released on 2007 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this project is to understand the potential mechanisms of antimicrobial resistance of E. coli and opportunistic pathogens under disinfection conditions. The project involves molecular techniques to understand genetic changes in biofilm and suspended bacteria in response to different disinfectant conditions. It examines the effects of using single chemical disinfectants (free chlorine, chloramines, and chlorine dioxide) compared with UV light pretreatment, as well as the impact of pipe material (polycarbonate or cast iron) and E. coli mutations. Field studies include both surface water and groundwater.

Download or read book Ultraviolet Light Disinfection Technology in Drinking Water Application written by Science Applications International Corporation and published by . This book was released on 1996 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Controlling Disinfection By products and Microbial Contaminants in Drinking Water written by Robert M. Clark and published by DIANE Publishing. This book was released on 2001 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Treatment of Biofilms and Opportunistic Pathogens in Simulated Drinking Water Distribution Systems Using UV LEDs written by Carlos Jaser Lara de Larrea and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biofilm formation in drinking water distribution systems (DWDS) has important implications for public health due to the potential proliferation of opportunistic pathogens (OPs). To inhibit the formation of biofilms and OPs in DWDS, Ultraviolet Light Emitting Diode (UV-LED) technologies show great promise due to their small footprint and versatility. This research aimed to expand the understanding of biofilm growth in DWDS and the application of UV LEDs to inactivate them. This thesis examined: (1) the inactivation of Legionella pneumophila and Pseudomonas fluorescens in CDC biofilm reactors on cast iron and stainless steel coupons and (2) the inactivation of tap water natural microbiome biofilms (NMB) grown on biostud reactors. Then, organisms were cultured and subsequently exposed to UV LEDs at 280 and 365 nm. Overall, organisms were more sensitive to 280 nm; however, 365 nm could be further investigated for possible photolytic reactions. Further work should consider scaling.