title: Effects of chemical agent injections on genotoxicity of wastewater in a microfiltration-reverse osmosis membrane process for wastewater reuse.
abstract: With combined microfiltration (MF)/ultrafiltration (UF) and reverse osmosis (RO) process being widely used in municipal wastewater reclamation, RO concentrate with high level genotoxicity is becoming a potential risk to water environment. In this study, wastewater genotoxicity in a MF-RO process for municipal wastewater reclamation and also the effects of chemical agent injections were evaluated by SOS/umu genotoxicity test. The genotoxicity of RO concentrate ranged 500-559 μg 4-NQO (4-nitroquinoline-1-oxide)/L and 12-22 μg 4-NQO/mg DOC, was much higher than that of RO influent. Further research suggested that Kathon biocide was a key chemical agent associated with the genotoxicity increase. Kathon biocide used in RO system was highly genotoxic in vitro and Kathon biocide retained in RO system could contribute to a higher genotoxicity of RO concentrate. Hence, treatments for biocides before discharging are necessary. Chlorination of secondary effluent could significantly decrease the genotoxicity and increasing chlorine dosage could be an efficacious method to decrease the genotoxicity of RO concentrate. According to the result of the experiment, the dosage of chlorine in dual-membrane process could be set to about 2.5 mg Cl₂/L. The effect of antiscalant (2-phosphomobutane-1,2,4-tricarboxylic acid) was also investigated; it turned out to have no effect on genotoxicity.
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China.tangfangstar@gmail.com
authors.forename: Fang
authors.initials: F
authors.lastname: Tang
authors.forename: Hong-Ying
authors.initials: HY
authors.lastname: Hu
authors.forename: Qian-Yuan
authors.initials: QY
authors.lastname: Wu
authors.forename: Xin
authors.initials: X
authors.lastname: Tang
authors.forename: Ying-Xue
authors.initials: YX
authors.lastname: Sun
authors.forename: Xiao-Lei
authors.initials: XL
authors.lastname: Shi
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Huang
mesh_terms: D002681:China; D002713:Chlorine / Q000737:chemistry; D002947:Cities; D004867:Equipment Design; D009153:Mutagens / Q000032:analysis*; D009995:Osmosis; D012486:Salmonella typhimurium / Q000187:drug effects; D013844:Thiazoles / Q000032:analysis; D014462:Ultrafiltration / Q000379:methods*; D014865:Waste Disposal, Fluid / Q000379:methods; D062065:Wastewater; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
chemical_list: D002713:Chlorine; D009153:Mutagens; D013844:Thiazoles; D062065:Wastewater; D014874:Water Pollutants, Chemical; C037057:Kathon 886
keywords: Chlorination; Genotoxicity; Kathon biocide; Reverse osmosis; Wastewater reclamation