Xiaona Chu

Effects of water matrix on virus inactivation using common virucidal techniques for condensate urine disinfection.

Three common virucidal techniques (chlorine, UV and UV/TiO2) were applied to inactivate virus (MS2 and Phi X174) in condensate water after the evaporation of source-separated urine for reclaimed water. The inactivation efficiencies were compared with the results of previous studies, with the emphasis on the analysis of water matrix effects. Results showed that all virus inactivation in condensate water were lower than the control (in sterilized DI water). As for UV/TiO2 disinfection, both nitrate and ammonia nitrogen could promote slightly viral inactivation, while the inhibition by urea was dominant. Similarly, ammonia nitrogen had greater impacts on chlorine disinfection than urea and nitrate. In contrast, all water matrices (urea, nitrate and ammonia nitrogen) had little influence on UV disinfection. Based on the findings in this study, UV disinfection could be recommended for disinfecting the reclaimed water from the evaporation of source-separated urine.

Pilot-scale UV/H2O2 study for emerging organic contaminants decomposition.

Abstract Human behaviors including consumption of drugs and use of personal care products, climate change, increased international travel, and the advent of water reclamation for direct potable use have led to the introduction of significant amounts of emerging organic contaminants into the aqueous environment. In addition, the lower detection limits associated with improved scientific methods of chemical analysis have resulted in a recent increase in documented incidences of these contaminants which previously were not routinely monitored in water. Such contaminants may cause known or suspected adverse ecological and/or human health effects at very low concentrations. Conventional drinking water treatment processes may not effectively remove these organic contaminants. Advanced oxidation process (AOP) is a promising treatment process for the removal of most of these emerging organic contaminants, and has been accepted worldwide as a suitable treatment process. In this study, different groups of emerging contaminants were studied for decomposition efficiency using pilot-scale UV/H2O2 oxidation setup, including EDCs, PPCPs, taste and odor (T&O), and perfluorinated compounds. Results found that MP UV/H2O2 AOP was efficient in removing all the selected contaminants except perfluorinated compounds. Study of the kinetics of the process showed that both light absorption and quantum yield of each compound affected the decomposition performance. Analysis of water quality parameters of the treated water indicated that the outcome of both UV photolysis and UV/H2O2 processes can be affected by changes in the feed water quality.

Effect of salinity on medium- and low-pressure UV disinfection of Vibrio cholerae

The problem of biological invasions attributed to ballast water release is an ongoing problem that threatens ecosystems and human health. Ultraviolet (UV) radiation has been increasingly used for ballast water treatment mainly due to the advantages of short contact time and minimized harmful disinfection by products. In this study, the impact of salinity on the inactivation of Vibrio cholerae (NCTC 7253) was examined, and comparison of inactivation level and disinfection kinetics after medium-pressure (MP) (1 kW) and low-pressure (LP) (10 W) UV irradiation was made. MP UV exposure resulted in higher inactivation efficacy against V. cholerae than LP UV exposure especially at lower UV doses (≤3 mJ cm-2) and salinity had a negative impact on both MP and LP UV disinfection, especially at higher UV doses (≥3 mJ cm-2 for MP and ≥4 mJ cm-2 for LP). To understand the mechanisms of salinity effect on V. cholerae, the enzyme-linked immunosorbent assay (ELISA) was employed to determine the number of cyclobutane pyrimidine dimers (CPDs), one major type of DNA damage. No significant effects of salinity were found at the CPDs level except for 3% artificial seawater after LP UV exposure case. It is imperative that site-specific conditions of salinity be taken into account in the design of UV reactors to treat V. cholerae and other species.

Effects of salinity and temperature on inactivation and repair potential of Enterococcus faecalis following medium‐ and low‐pressure ultraviolet irradiation

To investigate the medium‐pressure (MP) and low‐pressure (LP) Ultraviolet (UV) susceptibility and the repair potential of Enterococcus faecalis (DSM 20478) after UV treatment.