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UV disinfection is noted to have some problems, one of which is photoreactivation. Photoreactivation allows inactivated microorganisms to regain viability following UV disinfection. The objective of this study is to determine the susceptibility of enterohemorrhagic Escherichia coli (EHEC) O26, vancomycin resistant Enterococcus (VRE), and Pseudomonas aeruginosa to UV radiation and photoreactivation. The conclusions obtained in this study can be summarized as follows. EHEC O26 exhibited apparent inactivation under sunlight after photoreactivation following UV inactivation. VRE exhibited apparent photoreactivation. The dose of UV light required for 90% inactivation of VRE with and without photoreactivation was 10.9 and 24.2 mW sec/cm 2 , respectively. P. aeruginosa exhibited apparent photoreactivation under fluorescent lamp and weak regrowth under dark conditions following UV inactivation. The dose of UV light required for 90% inactivation of P. aeruginosa with and without photoreactivation was 4.1 and 5.2 mW sec/cm 2 , respectively.

The removal characteristics of indigenous microorganisms in wastewater treatment unit processes were studied at five operating wastewater treatment plants. The removal efficiencies of the selected microorganisms in each unit process were dependent upon not only the systems but also the kinds of microorganisms. In almost all processes, the removal efficiencies of total coliforms were similar to or higher than those of Clostridium perfringens except for filtration processes. In the additional survey, focussed on the comparison of removal efficiencies of total coliforms, Cl. perfringens and coliphages, little difference was found between CL perfringens and coliphages. From these results, it may be suggested that CL Perfringens is an effective indicator microorganism for evaluating microorganism removal in wastewater treatment processes and systems.

No abstract

There is a need to conduct more research on the degradability of pharmaceuticals and personal care products in environmental waters for controlling water pollution and sustaining water system. In this study, we added tetracycline to 6 water samples, incubated the samples in the laboratory, and determined the degradation rates and bacterial growth in each sample for analysis of the growth of tetracycline-resistant or tetracycline-degrading bacteria and the mechanism of tetracycline degradation. The main conclusions obtained in this study can be summarized as follows: (1) The maximum degradation of tetracycline was in the Unoke River water samples with 60% degradation in the sample with the initial tetracycline concentration of 1 mg/L. (2) Not all bacteria growing in the water environment containing tetracycline were capable of degrading the antibiotic. (3) The ability of bacteria to degrade tetracycline in environmental water systems may be useful in microbial source tracking.