The control of red water occurrence and opportunistic pathogens risks in drinking water distribution systems: A review

Many problems in drinking water distribution systems (DWDSs) are caused by microbe, such as biofilm formation, biocorrosion and opportunistic pathogens growth. More iron release from corrosion scales may induce red water. Biofilm played great roles on the corrosion. The iron-oxidizing bacteria (IOB) promoted corrosion. However, when iron-reducing bacteria (IRB) and nitrate-reducing bacteria (NRB) became the main bacteria in biofilm, they could induce iron redox cycling in corrosion process. This process enhanced the precipitation of iron oxides and formation of more Fe3O4 in corrosion scales, which inhibited corrosion effectively. Therefore, the IRB and NRB in the biofilm can reduce iron release and red water occurrence. Moreover, there are many opportunistic pathogens in biofilm of DWDSs. The opportunistic pathogens growth in DWDSs related to the bacterial community changes due to the effects of micropollutants. Micropollutants increased the number of bacteria with antibiotic resistance genes (ARGs). Furthermore, extracellular polymeric substances (EPS) production was increased by the antibiotic resistant bacteria, leading to greater bacterial aggregation and adsorption, increasing the chlorine-resistance capability, which was responsible for the enhancement of the particle-associated opportunistic pathogens in DWDSs. Moreover, O-3-biological activated carbon filtration-UV-Cl-2 treatment could be used to control the iron release, red water occurrence and opportunistic pathogens growth in DWDSs. (C) 2021TheResearch Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

Many problems in drinking water distribution systems are caused by microbiological factors, including biofilm formation, biocorrosion, and the growth of opportunistic pathogens. Iron-reducing bacteria and nitrate-reducing bacteria in biofilm play key roles in inhibiting corrosion effectively. The increase in antibiotic resistant bacteria due to micropollutants leads to greater bacterial aggregation and adsorption, enhancing the presence of particle-associated opportunistic pathogens in the distribution systems. Treatment methods such as O-3-biological activated carbon filtration-UV-Cl-2 can be used to control iron release, red water occurrence, and opportunistic pathogens growth.