Effects of bromide ion on the formation and toxicity alteration of halonitromethanes from nitrate containing humic acid water during UV/chlor(am)ine disinfection

Tingting Huang; Lin Deng; Tao Wang; Xueying Liao; Jun Hu; Chaoqun Tan; Rajendra Prasad Singh

doi:10.1016/j.watres.2022.119175

Effects of bromide ion on the formation and toxicity alteration of halonitromethanes from nitrate containing humic acid water during UV/chlor(am)ine disinfection

Water Res. 2022 Oct 15:225:119175. doi: 10.1016/j.watres.2022.119175. Epub 2022 Sep 27.

Authors

Tingting Huang¹, Lin Deng², Tao Wang³, Xueying Liao⁴, Jun Hu⁵, Chaoqun Tan⁶, Rajendra Prasad Singh⁷

Affiliations

¹ Department of Municipal Engineering, Southeast University, Nanjing 211189, China. Electronic address: xiaohuang970716@163.com.
² Department of Municipal Engineering, Southeast University, Nanjing 211189, China. Electronic address: denglin10974@163.com.
³ Department of Municipal Engineering, Southeast University, Nanjing 211189, China. Electronic address: wangt127@163.com.
⁴ Department of Municipal Engineering, Southeast University, Nanjing 211189, China. Electronic address: 220181167@seu.edu.cn.
⁵ Department of Municipal Engineering, Southeast University, Nanjing 211189, China. Electronic address: hujun1988@zjut.edu.cn.
⁶ Department of Municipal Engineering, Southeast University, Nanjing 211189, China. Electronic address: tancq@seu.edu.cn.
⁷ Department of Municipal Engineering, Southeast University, Nanjing 211189, China. Electronic address: rajupsc@seu.edu.cn.

PMID: 36191529
DOI: 10.1016/j.watres.2022.119175

Abstract

UV/chlor(am)ine are efficient for achieving multiple-barrier disinfection and maintaining residuals, while bromide (Br^-) has notable impacts on the formation and toxicity of halonitromethanes (HNMs) during UV/chlor(am)ine disinfection. This study investigated the effects of Br^- on HNMs formation and toxicity alteration during UV/chlor(am)ine disinfection of nitrate containing humic acid (HA) water. Results reveal that the maximum concentration of HNMs during UV/chlorine disinfection was 12.03 μg L^-1 with 0.2 mg L^-1 Br^-, which was 22.5% higher than that without Br^-, and the predominant species of HNMs were converted from trichloronitromethane (TCNM) to dibromonitromethane (DBNM) and tribromonitromethane (TBNM). However, the maximum concentration of HNMs during UV/chloramine disinfection was 3.69 μg L^-1 with 0.2 mg L^-1 Br^-, which was increased by 26.0% than that without Br^-, and the predominant species of HNMs were converted from dichloronitromethane (DCNM) to bromochloronitromethane (BCNM) and DBNM. Notably, the HNMs species and yields during UV/chloramine disinfection were less than those during UV/chlorine disinfection, primarily due to the higher concentrations of HO· and reactive chlorine/bromine species in UV/chlorine. Also, in the ranges of the Br^-:Cl₂ molar ratio from 0 to 0.32 and pH from 6.0 to 8.0, the Br^-:Cl₂ molar ratio of 0.16 and acidic pH contributed to the HNMs formation during UV/chlorine disinfection, and a high Br^-:Cl₂ molar ratio and neutral pH contributed to the HNMs formation during UV/chloramine disinfection. Note that the incorporation of Br^- significantly improved the calculated cytotoxicity (CTI) and genotoxicity (GTI) of HNMs formed, and the calculated CTI and GTI of HNMs formed during UV/chloramine disinfection were 28.19 and 48.90% of those during UV/chlorine disinfection. Based on the diversity of nitrogen sources, the possible formation pathways of HNMs from nitrate containing HA water were proposed during UV/chlor(am)ine disinfection in the presence of Br^-. Results of this study indicated that UV/chloramine can reduce the formation and toxicity of HNMs efficiently.

Keywords: Bromide; Halonitromethanes; Nitrate; UV/chlor(am)ine.

MeSH terms

Bromides
Bromine
Chloramines
Chlorine
Disinfectants*
Disinfection / methods
Halogenation
Humic Substances
Nitrates
Nitrogen
Water
Water Pollutants, Chemical* / analysis
Water Purification* / methods

Substances

chloramine
Chloramines
Chlorine
Humic Substances
Bromides
Nitrates
Bromine
Water
Water Pollutants, Chemical
Nitrogen
Disinfectants