title: Increased formation of halomethanes during chlorination of chloramphenicol in drinking water by UV irradiation, persulfate oxidation, and combined UV/persulfate pre-treatments.
abstract: Ultraviolet/persulfate (UV/PS) has been widely used to generate sulfate radicals for degradation of water organic pollutants in previous studies. However, its impacts on disinfection byproduct formation during post-chlorination of degraded compounds is unclear. The objective of this study was to evaluate the impacts of UV irradiation, PS oxidation, and the combined UV/PS advanced oxidation process (AOP) pre-treatments on halomethane formation during the following chlorination of chloramphenicol (CAP), a model antibiotic commonly found in wastewater-impacted water. Results showed that CAP could be transformed to more trichloromethane (TCM) than monochloromethane (MCM) and dichloromethane (DCM) in the presence of excess chlorine. UV photolysis, PS oxidation and UV/PS AOP all directly decomposed CAP to produce halomethanes (HMs) before post-chlorination. Moreover, UV and UV/PS pre-treatments both enhanced the formation of all the HMs in the subsequent chlorination. PS pre-oxidation decreased the TCM formation during post-chlorination, but increased the yields of MCM, DCM and total HMs. UV pre-irradiation significantly increased the bromide utilization of HMs, whereas UV/PS pre-oxidation decreased the bromine incorporation and utilization of HMs from the chlorination of CAP in a low-bromide water. UV irradiation, PS oxidation, and UV/PS AOP can inactivate pathogens and degrade organic pollutants, but this benefit should be weighed against a potential risk of the increased halomethane formation from degraded organic pollutants with and without post-chlorination.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Ministry of Education Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. Electronic address: feedwater@126.com.
authors.forename: Chu
authors.initials: C
authors.lastname: Wenhai
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Ministry of Education Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China; Research & Service Center for Environmental Industry, Yancheng 224051, China.
authors.forename: Chu
authors.initials: C
authors.lastname: Tengfei
authors.affiliation: School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China.
authors.forename: Du
authors.initials: D
authors.lastname: Erdeng
authors.affiliation: Department of Earth and Environmental Studies, Montclair State University, Montclair, NJ 07043, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Deng
authors.affiliation: School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, China.
authors.forename: Guo
authors.initials: G
authors.lastname: Yingqing
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Ministry of Education Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. Electronic address: gaonaiyun@tongji.edu.cn.
authors.forename: Gao
authors.initials: G
authors.lastname: Naiyun
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000528:radiation effects; D001965:Bromides / Q000737:chemistry; D002701:Chloramphenicol / Q000737:chemistry / Q000528:radiation effects; D002713:Chlorine / Q000737:chemistry; D060766:Drinking Water / Q000737:chemistry; D054879:Halogenation; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D010084:Oxidation-Reduction; D010782:Photolysis; D013431:Sulfates / Q000737:chemistry*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000528:radiation effects; D018508:Water Purification / Q000379:methods
chemical_list: D000900:Anti-Bacterial Agents; D001965:Bromides; D060766:Drinking Water; D006846:Hydrocarbons, Halogenated; D013431:Sulfates; D014874:Water Pollutants, Chemical; D002713:Chlorine; D002701:Chloramphenicol
keywords: Chloramphenicol; Disinfection byproducts; Drinking water safety; Halomethanes; Pharmaceuticals; Ultraviolet/persulfate (UV/PS)