Utilization Of Biodegradable Organic Matter By Biofilms In Drinking Water Distribution Systems Microform

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.

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.

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

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

Biofilms are ubiquitous in drinking water distribution systems, regardless of the type of treatment or disinfection employed by a utility. In general these biofilms pose no direct health threat unless their growth becomes excessive or pathogens that are inadvertently introduced into a distribution system become part of the biofilm microbial community. While biofilm can cause problems associated with taste and odor or corrosion, the possible presence and persistence of opportunistic pathogens within the biofilm may be the most important concern. Current methods employed to minimize biofilm include the use of residual disinfectants, reduction of organic matter or inorganic electron donors (e.g. ammonia) in the water, use of pipe materials and coatings that reduce the amount of biofilm accumulation, frequent flushing of pipelines, and the practice of corrosion control treatment when corroded iron pipes are present. New strategies for the control of biofilm are being discovered and tested in a wide variety of settings, but generally not within the context of drinking water distribution systems. It is therefore important to investigate the most promising new biofilm control strategies to determine their applicability to the very complex drinking water distribution system environment. The goal of this research was to investigate novel biofilm control strategies and technologies that could possibly be applied to drinking water systems. The intent of the research was to serve as an exploratory look at new control options and determine if any could warrant. Specific objectives of the work included: .Perform laboratory scale investigation of three control technologies using rotating annular reactors to simulate a drinking water distribution pipeline. .Select the most promising technology and test that technology in actual field settings under a variety of water quality and disinfectant conditions.

Natural organic matter (NOM) is a concern in many surface waters and must be removed by water treatment processes for cost-effective production of safe and aesthetically pleasing drinking water. Biological filtration is an appealing NOM removal method due to its simplicity and low maintenance requirements. Biofiltration is not traditionally used in water treatment headworks, however biofiltration without pretreatment (BFwp) breaks with common practice to function as both particle and biodegradable NOM removal as a 1st stage process. BFwp makes use of indigenous microbial populations embedded in a biofilm matrix to remove biodegradable organic matter (BOM) from raw source water. This configuration is a viable pretreatment strategy for both low and high pressure membrane filtration due to its ability to remove both particulate and soluble BOM, thereby mitigating biofouling on the membrane surface. Biofouling has been described as the "Achille's heel" of membrane filtration (Flemming et al., 1997) due to its effects of increased operational cost and shortened membrane life-span. Therefore, a targeted effort is needed to understand how biofilter ecology affects performance both in the biofilter and downstream in membrane filtration units. Two parallel pilot scale BFwp units with dual-media were used in the current study for a seasonal characterisation of biofilter microbial dynamics and performance. Refurbishment of the biofilter pilot plant was performed by Dr. Ahmed Elhadidy and Brad Wilson, former students of the NSERC chair in water treatment. The current seasonal characterization spanned 14 months and made use of both new sample material as well as archived samples from Dr. Elhadidy. Biofilter media biomass was assessed using both adenosine tri-phosphate (ATP) and flow cytometric methods. Total protein, carbohydrate and free DNA of the media biofilm extracellular polymeric substances (EPS) were determined. Polymerase Chain Reaction - Denaturing Gradient Gel Electrophoresis (PCR-DGGE) was used to create microbial community fingerprint profiles of the biofilter feed and media. It was found that source water quality played a significant role in shaping BFwp microbial communities. Multivariate analysis of the PCR-DGGE fingerprints showed a media biofilm community shift occurred in response to high ammonia, high low molecular weight acids (LMW-acids) concentrations in the raw feed during January-February 2015. This low temperature, high ammonia and LMW-acids induced shift was accompanied by a rise in media biomass and EPS. Lower DOC and biopolymer removals were observed during the January-February 2015 community shift, however this was attributed largely to the effects which lower feed temperatures have on microbial biodegradation kinetics. No differences were found in community structures between media types, depths, or biofilter columns, however source water exhibited lower diversities and markedly different community structure than those of media biofilms. It was determined that media diversity and richness were high and did not exhibit seasonal fluctuations. As such these parameters could not be reliably related to biofilter DOC and biopolymer removal performance. In his investigation of biofiltration as a pretreatment for nanofiltration (NF), Dr. Elhadidy archived samples for molecular analysis that were used in the current study. PCR-DGGE was performed on extracted DNA from source water, media, and fouled membrane samples for bacteria, archaea, and fungi. Archaea were present in all samples, however their abundance was roughly 1000 fold less than bacteria, which made it difficult to assess their significance in the biofiltration and NF processes. Fungi were only screened for in one media and one source water sample during method development; both samples were positive. Archaeal community organisation was similar to that of bacteria during the autumn BF-NF experiment, however no community organisation was discernible during the winter experiment. Bacterial community structures from the autumn experiment showed that fouled NF membranes fed raw water clustered together with biofilter media, indicating feed water rather than substrate material influences bacterial community organisation. Comparatively, NF membranes fed with biofilter effluent produced a cluster of drastically dissimilar bacterial communities, which corresponded with improved flux and reduced biofoulant biomass. The microbial communities of biofiltration exhibited dynamic responses to feed water quality in both the seasonal and the nanofiltration studies. Biomass and EPS were highly correlated and their levels changed in response to community shifts, which in the seasonal and nanofiltration studies, were precipitated by changes in feed ammonia and BOM.