Assessing comprehensive performance of biofilm formation and water quality in drinking water distribution systems

Abstract

Environmental fluctuations shape biofilm formation in drinking water distribution systems (DWDSs) and therefore distributed water quality. Yet the comprehensive performance in response to complex environmental conditions remains unclear. We investigated biofilm formation and distributed water quality under various nutrients, including chlorine concentrations and hydrodynamic conditions. Results showed that environmental fluctuations collectively induced changes in microbial propagation, which were mostly associated with turbidity variations, concentrations of total organic carbon, NH4+-N and soluble phosphorus compared to the other parameters. Fuzzy pattern recognition analysis integrating multiple water quality indicators revealed that low nutrient availability and addition of mild chlorine at 0.50 mg/L at 0.50 m/s flow velocity were the most favorable conditions screened for optimized comprehensive performance, while nutrient supplements yielded significant performance deterioration. These quantitative estimations offer new insights into advanced understanding of the system performance responding to often complex environmental fluctuations, essential for optimized design and practical functioning of DWDSs.

Linking Microbial Community Composition in Treated Wastewater with Water Quality in Distribution Systems and Subsequent Health Effects

“…Bacteria are generally the dominant members of biofilm microbial communities in DWDS due to their high growth rates, relatively small size, adaptation capabilities, and ability to produce EPS [25]. Biofilm embedded microbes account for about 95% of the total biomass in DWDS, and use complex structures to protect themselves against antimicrobials, acquire new genetic traits, and metabolic activities for survival in a hostile environment [26]. Viruses, fungi, algae, and protozoa are also present, but at relatively smaller proportions [20].…”

“…One of the factors affecting water quality in DWDS is environmental fluctuations of the pipes. The presence of suspended and biofilm embedded microbes in DWDS have been shown to degrade the quality of distributed water for decades [26]. These authors investigated biofilm formation and water quality under various nutrients in DWDS, including chlorine concentrations and hydrodynamic conditions.…”

“…Chemical processes include chlorination and application of chloramines. Some biological processes target the quorum sensing process or EPS formation [26]. For many years, application of chlorine has been the main method used to limit the formation of biofilms in DWDSs.…”

“…One of the most recent technologies for the control of biofilm growth is the use of nanotechnology agents [26]. Nanoparticles (NPs) are different from their bulk chemical counterparts because of their large surface area to volume ratio, which creates a higher number of functional sites and can enhance the influence of NPs on a given microorganism.…”

“…Other methods for biofilm control also include strategies to reduce the levels of assimilable organic carbon (AOC), as well as the concentration of suspended microbes in drinking water prior to entering the distribution system (typically through membrane biofiltration). Nutrient limitations can also inhibit biofilm formation, induce biofilm dispersal, or both, ultimately reducing or delaying the impact of biofilms on engineered systems [26,43,[109][110][111]. UV disinfection, oxidative treatments (ozonation), and a combination of UV and H 2 O 2 treatment are other technologies that could also be used to reduce suspended microorganisms in drinking water prior to entering the distribution system, and these treatments may reduce chlorine demand and corrosion potential [112].…”