Date of Award

8-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Plant and Environmental Science

Advisor

Chow, Alex

Committee Member

Park , Dara

Committee Member

Sharp , Julia

Abstract

Formation of disinfection byproducts (DBPs) during Escherichia coli K12 and Pseudomonas aeruginosa PAO1 inactivation under four disinfection processes, including chlorination, chloramination, photo-Fenton reaction, and TiO2/UV photocatalytic inactivation were examined. Factors of pH (5 or 8) and different disinfectant dosages were also investigated in order to balance the risks of DBP formation and bacterial cell viability in the four treatment processes. Chlorination had the fastest bacterial inactivation whereas chloramination, photo-Fenton, and TiO2/UV requiring longer contact times to achieve the same inactivation efficiency. In spite of the lag phase in the treatment processes, both photo-Fenton and TiO2/UV achieved 100% bacteria reduction after 80-min exposure, exceeding effectiveness of the chlorination (5.6 log reduction) and chloramination (4.4 log reduction). In addition, chlorination had the highest trihalomethanes (THMs) of 5.77 ± 0.21 μg/L and haloacetonitriles (HANs) of 1.02 ± 0.15 μg/L, followed by chloramination (with THMs of 1.37 ± 0.03 μg/L and HANs of 0.17 ± 0.04 μg/L). No THMs or HANs was detected in photo-Fenton or TiO2/UV processes. In general, the risks of DBP and bacterial cells in finished water can be reduced through efficient operational conditions: Acidic pH condition for chlorination, chloramination, and TiO2/UV photocatalytic inactivation. For photo-Fenton reaction, no DBPs formed with equal similar cell viability reduction observed under pH range of 5 - 8.

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