Formation of disinfection byproducts (DBPs) during Escherichia coli K-12 and Pseudomonas aeruginosa inactivation under four disinfection processes, including chlorination, chloramination, photo-Fenton reaction, and TiO2/UV were examined. Factors of water pH (5.0 or 8.0), disinfectant contact time (0-48 hours), and concentrations of dissolved organic matter (0, 2, or 4mg/L humic acid) were also investigated to evaluate the optimal condition to balance the risks between DBP formation and bacterial cell density. Results showed chlorination had the highest bacterial inactivation efficiency and completely inactivated bacterial cells within minutes. Longer contact times were required for chloramination, photo-Fenton, and TiO2/UV to achieve the same inactivation efficiency. However, chlorination had the highest trihalomethane (THM) and haloacetonitrile (HAN) formations, whereas chloramination produced about 25% of THMs in chlorination processes under the same experimental conditions. No THMs or HANs was detected in photo-Fenton or TiO2/UV processes. The kinetic studies demonstrated that larger portion of THMs was produced in a much later time after bacterial being inactivated. The pH effect study also suggested less DBP formation and higher inactivation efficiency occurred in a lower pH condition. Our study demonstrated that we could minimize the risks of both DBP and bacterial cells in finished water through efficient treatment processes..

Optimizing disinfection efficacy:  Tradeoff between bacterial inactivation and disinfection byproducts formation

248th National Meeting (2014)

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