Abstract
AbstractMicrobial regrowth in premise plumbing is a threat to water safety. Disinfectant residuals are often diminished during water transportation and stagnation, leading to the regrowth of opportunistic pathogens. Although microbial regrowth potential is mostly determined by water treatment, little is known about how each treatment step affects two key factors that contribute to microbial regrowth potential: biodegradable organic matter and microbial abundance. In this study, we operated annular reactors to evaluate the microbial regrowth potential of water shaped after each treatment step in a full-scale drinking water treatment plant with ozonation and biological activated carbon filtration. The assimilable organic carbon and total cell count (TCC) were stable at all treatment steps during the sampling period from July to October 2015. The assimilable organic carbon consumption and TCC net increase in the annular reactors indicated that apparent growth yields (cell number base) of microbial communities were different in each reactor. Regrowth potential evaluated by indigenous microbial community in finished water was reduced to 22% of that in raw water, while 75% of assimilable organic carbon in raw water remained in finished water. It suggested that treatment performance evaluated by indigenous microbial communities was better than that evaluated by assimilable organic carbon.
Highlights
Microbial regrowth in water distribution systems and premise plumbing deteriorates drinking water hygiene and biological safety (Liu et al 2014; Proctor et al 2017; Ling et al 2018; Chan et al 2019)
We aimed to investigate the changes in microbial regrowth potential in water by operating annular reactors receiving effluents from different treatment steps in a full-scale advanced drinking water treatment plant
While Dissolved organic carbon (DOC) concentrations steadily decreased from raw water to finished water (Supplementary Material, Figure S2), the assimilable organic carbon (AOC) concentrations increased and decreased
Summary
Microbial regrowth in water distribution systems and premise plumbing deteriorates drinking water hygiene and biological safety (Liu et al 2014; Proctor et al 2017; Ling et al 2018; Chan et al 2019). The regrowth of opportunistic pathogens, such as Legionella pneumophila and Mycobacterium avium, significantly impacts human health (van der Wielen & van der Kooij 2013; Gebert et al 2018; Nescerecka et al 2018; Waak et al 2018, 2019; Donohue et al 2019). These opportunistic pathogens in premise plumbing impose a more serious health burden than enteric bacteria for waterborne infectious diseases in the USA (Collier et al 2021).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
