title: Formation of THMs and HANs during bromination of Microcystis aeruginosa.
abstract: Bromine-contained disinfectants and biocides are widely used in swimming pools, recreational waters and cooling towers. The objective of this study was to evaluate the formation of thrihalomethanes (THMs) and haloacetonitriles (HANs) and their cytotoxicity in algae solutions during free bromine disinfection. Disinfection by-products formation potential experiments were conducted using model solutions containing 7 mg/L (as total organic carbon) Microcystis aeruginosa cells. Effects of free bromine dosage, pH and ammonia were investigated. The results showed that brominated disinfection by-products were the major products when free bromine was applied. The total THMs formed during bromination was much as that formed during chlorination, whereas HANs were elevated by using bromination instead of chlorination. Dibromoacetonitrice (C2H2NBr2) and bromoform (CHBr3) were the only detected species during free bromine disinfection. The production of C2H2NBr2 and CHBr3 increased with disinfectant dosage but decreased with dosing ammonia. CHBr3 increased with the pH changing from 5 to 9. However, C2H2NBr2 achieved the highest production at neutral pH, which was due to a joint effect of variation in hydrolysis rate and free bromine reactivity. The hydrolysis of C2H2NBr2 was base-catalytic and nearly unaffected by disinfectant. Finally, estimation of cytotoxicity of the disinfected algae solutions showed that HANs formation was responsible for the majority of toxicity. Considering its highest toxicity among the measured disinfection by-products, the elevated C2H2NBr2 should be considered when using bromine-related algaecide.
authors: School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China. pqyz@hotmail.com
authors: Yunzhu
authors: Y
authors: Pu
authors: Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
authors: Lingzhao
authors: L
authors: Kong
authors: School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China.
authors: Xin
authors: X
authors: Huang
authors: School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China.
authors: Guoji
authors: G
authors: Ding
authors: State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200091, China.
authors: Naiyun
authors: N
authors: Gao
mesh_terms: D001966:Bromine / Q000378:metabolism*; D002849:Chromatography, Gas; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D046931:Microcystis / Q000378:metabolism*
chemical_list: D001966:Bromine