Understanding The Impacts Of Organic Matter On Microbial Biofilms In Engineered Drinking Water Systems

The increasing occurrence and severity of cyanobacterial harmful algal blooms (HABs) in freshwater have continuously challenged the safe drinking water supply. During HAB, public attention mainly focuses on the cyanotoxins, which associated with health issues, while HAB also generated massive amounts of algal cells, increasing the loading of algal organic matter (AOM) in the drinking water treatment plants (DWTPs). AOM is an algae-derived autochthonous natural organic matter (NOM), which contains high fraction of hydrophilic and nitrogenous compounds. Conventional treatment processes, comprised of coagulation, sedimentation, and granular media filtration, are known to be ineffective in completely removing NOM, including AOM [1, 2]. Although ozone has been widely adopted by water utilities to break down complex organic compounds and reduce DBP formation, ozonation practices can adversely increase concentrations of assimilable organic carbon (AOC), which in turn can be rapidly utilized and support biofilm growth in downstream filters and drinking water distribution systems [3, 4]. Currently, remain largely unknown for the growth of biofilms under the impacts of different NOM, including AOM in the filters and drinking water distribution systems (DWDSs). Therefore, the main research goal of this study is to investigate the impacts of organic matter on microbial biofilms in engineered drinking water systems (EDWSs). Specifically, the first objective of this study aimed to examine how the assembly processes and their associated factors (e.g., influent characteristics, biological interactions) drive the temporal dynamics of bacterial communities in full-scale BAC filters, which underwent ozone implementation to better handle the adverse effects of HABs. The obtained results revealed that along with the increase of bacterial taxonomic richness and evenness, stochastic processes became more crucial to determine the bacterial community assembly in the summer and autumn after ozone implementation. Moreover, their corresponding networks possessed simple network structures with lower modularity than other seasons, which implied lesser biological interactions among bacterial populations. Among the monitored physiochemical properties of filter influents, temperature and nutrient bioavailability (i.e., AOC concentrations) as well as biological interactions can be crucial drivers that impact the balance between these two processes and the taxonomic diversity of bacterial communities in BAC filters. The second objective of this study was to examine the effects of two widely present NOM, treated AOM and humic substances (HS), on biofilm development under unchlorinated DWDS conditions. Although great efforts have been made to remove NOM in DWTPs, remaining NOM still exists in the filter effluent and subsequently enter DWDSs. This unremoved NOM can support the growth of microbial biofilms in DWDS. Thus, the impact of AOM and HS on the formation, chemical composition, and microbial community structures of biofilms was evaluated. The 16S rRNA gene sequencing analyses revealed that the bacterial communities in biofilms were clustered with the organic matter types in bulk water, where Family Comamonadaceae was the most dominant but showed different temporal dynamics depending on the organic matter characteristics in bulk water. Higher diversity was observed in the biofilms grown in AOM-impacted bulk water (BFAOM) than biofilms grown in HS-impacted (BFHS) and R2A-impacted bulk water (BFR2A) as the biofilms matured. In addition, some taxa (e.g., Rhodobacteraceae, and Sphingomonadaceae) were enriched in BFAOM compared to BFHS and BFR2A. The biofilm image analysis results indicated that compared to BFHS, BFAOM and BFR2A had relatively thinner and heterogeneous physical structures with lower amounts of cell biomass, extracellular polymeric substances (EPS), and higher EPS protein/polysaccharide ratios. The third objective of this study was to elucidate how different types of organic matter, including AOM and HS, affect biomolecular compositions of biofilms and subsequent DBP formation. In order to control biofilm formation in DWDS, water utilities apply disinfectants such as chlorine or monochloramines. However, these applied disinfectants can lead to the formation of toxic DBPs due to the presence of organic-rich substances within biofilms. Therefore, the impact of organic matter composition on biomulecular composition of biofilms and their correlations with DBP formation were explored. The obtained results indicated that all biofilm samples comprised mostly of protein-like components (~90%), and to a lesser extent, humic-like components (~10%). Strong correlations were generally found between tryptophan-like substances and the studied DBP formation (R2min ≥ 0.76, P

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.

Aquatic Ecosystems and Microbial Biofilms: Significance, Dynamics, Prevention and Control provides a systematic introduction and review of state-of-the-art information on microbial biofilms in aquatic ecosystems and their control. The book is designed and developed to understand the microbial biofilms in aquatic ecosystems, their role, and the control strategies. The contents of the book are well discussed to get state-of-art knowledge on various topics such as the role of biofilms in marine ecosystems, microbial biofilms, and drinking water systems, biofilms in biofouling and biocorrosion, beneficial aspects of biofilms such as biogeochemical cycling, wastewater treatment, and in biodeterioration of organic materials. This book also provides comprehensive knowledge and in-depth scientific information on the role of biofilms and their contribution to antibiotic resistance, and also advanced technologies to understand biofilms such as metagenomics. The book offers comprehensive coverage of the most essential topics, including: Microbial biofilms in aquatic ecosystems. New horizons to understand the role of biofilms in biofouling and corrosion and their control measures. Beneficial role of aquatic biofilms such as in biogeochemical cycling,wastewater treatment, and biodeterioration of organic materials. Various strategies to collaborate interdisciplinary schemes worldwide to design and develop new methods for cleaner drinking water, and information on advanced techniques such as metagenomics to understand the diversity and functional role of aquatic biofilms. This book serves as a reference book for scientific investigators who would like to study biofilms in aquatic ecosystems, as well as researchers developing methodology in this field to study biofilm formation in aquatic ecosystems, their advantages and disadvantages, and control strategies.

This compilation covers all aspects of biodegradable organic matter in drinking water by addressing the improvement made to water treatment and quality during the last 20 years. This book is a must for researchers and a valuable reference and guidance tool for all water producers.

Microbial growth and contamination ("Biofouling") in water systems represents a significant threat to the quality of waters produced for the microelectronic, pharmaceutical, petroleum, paper, food and other manufacturing industries. Biofouling can lead to biologically induced corrosion ("Biocorrosion"), which can cause severe damage to the equipment. Both biofouling and biocorrosion are frequently not recognized in time, underestimated, or linked with the wrong causes. The book represents a new approach by introducing biofilm properties and dynamics as basic principles of biofouling and biocorrosion, thus providing a better understanding and the means of fighting the undesired effects of biofilms. The most important features are: Case histories of biofouling in water treatment.- Detection and monitoring of biofouling.- Reverse osmosis membrane biofouling.- Biocide efficacy and biofouling control.- Plant design considerations for preventing biofouling.- Case histories of biocorrosion.- Detection, monitoring, control and prevention of biocorrosion.- Fundamentals of biofouling and biocorrosion mechanisms.

Maintaining the microbial quality in distribution systems and connected installations remains a challenge for the water supply companies all over the world, despite many years of research. This book identifies the main concerns and knowledge gaps related to regrowth and stimulates cooperation in future research. Microbial Growth in Drinking Water Supplies provides an overview of the regrowth issue in different countries and the water quality problems related to regrowth. The book assesses the causes of regrowth in drinking water and the prevention of regrowth by water treatment and distribution. Editors: Dirk van der Kooij and Paul W.J.J. van der Wielen, KWR Watercycle Research Institute, The Netherlands

The development of biofilms and their role in public health - particularly drinking water - is often overlooked. Ideal for anyone interested in water related issues, Microbiological Aspects of Biofilms and Drinking Water presents an overview of the public health effects associated with drinking water. It highlights the microbiological aspects relat

The development of biofilms and their role in public health - particularly drinking water - is often overlooked. Ideal for anyone interested in water related issues, Microbiological Aspects of Biofilms and Drinking Water presents an overview of the public health effects associated with drinking water. It highlights the microbiological aspects relating to the development of biofilms. The first four chapters focus on the state of the water supply. The authors review methods for studying the epidemiological spread of waterborne infections and those used in surveillance and control of pathogenic microbes. He includes the methods used for the detection of pathogens of public health importance in drinking water. In the subsequent chapters the authors pay close attention to biofilm development within drinking water systems, underlining the public health threat. They cover the microbes important to public health and include the methods used to detect biofilms. In conclusion they review the methods involved in biofilm control - both conventional and biocidal treatments. Overall, Microbiological Aspects of Biofilms and Drinking Water provides a snapshot of public health and the water supply. It covers the future of drinking water and its associated health hazards and provides a deeper understanding of biofilms and how they provide a safe haven for pathogens and water related diseases.