Citation:

Zhang, C. AND J. Lu. Optimizing disinfectant residual dosage in engineered water systems to minimize the overall health risks of opportunistic pathogens and disinfection by-products. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 770:145356, (2021). https://doi.org/10.1016/j.scitotenv.2021.145356

Impact/Purpose:

Drinking water quality may have public health implications. Monitoring microbial water quality is critical to estimate the microbe-associated health risks of drinking water. However, a group of natural inhabitants of drinking water, opportunistic pathogens (OPs), occurs in EWSs at high densities, frequently causes water-related disease outbreaks, and is thus a major microbial factor threatening public health. Therefore, closely monitoring microbial water quality in EWSs, especially the dynamics of OPs, is an urgent task for the water industry to better protect public health. Legionella is a key natural inhabitant in EWSs with relatively high densities and correlates with important microbial (e.g., amoebae and biofilms) and physicochemical (e.g., disinfectant residuals) water quality parameters. For instance, Legionella and major OPs in EWSs share multiple key features such as disease-causing, disinfectant resistance, biofilm formation, and proliferation in amoebae. Thus, we propose that OP can be used to monitor for drinking water microbial water quality. Researches from institutes and managers from utilities could be interested in the results.

Description:

This Discussion argues that municipal water utilities may need to consider the health risks of both opportunistic pathogens (OPs) and disinfection by-products (DBPs) while selecting disinfectant residual dosages or levels in engineered water systems. OPs are natural inhabitants in municipal water systems and the leading cause of drinking-water-related disease outbreaks threatening public health. DBPs in water systems are genotoxic/carcinogenic and also significantly affect public health. Disinfectant residuals (such as free chlorine and chloramine residuals) dictate OP (re)growth and DBP formation in engineered water systems. Therefore, regulating the dosages or levels of disinfectant residuals is effective in controlling OP (re)growth and DBP formation. Existing effects assessing optimal disinfectant residual dosages focus solely on minimizing OP (re)growth or solely on DBP formation. However, selecting disinfectant residual dosages aiming to solely limit the formation of DBPs might compromise OP (re)growth control, and vice versa. An optimal disinfectant residual level for DBP formation control or OP (re)growth control might not be optimal for minimizing the overall or combined health effects of OPs and DBPs in drinking water. To better protect public health, water authorities may need to update the current residual disinfection practice and maintain disinfectant residuals in engineered water systems at an optimal level to minimize the overall health risks of OPs and DBPs.

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