Insight into mixed chlorine/chloramines conversion and associated water quality variability in drinking water distribution systems

Renjie Pan; Tian-Yang Zhang; Zheng-Xiong Zheng; Jian Ai; Tao Ye; Heng-Xuan Zhao; Chen-Yan Hu; Yu-Lin Tang; Jing-Jing Fan; Bing Geng; Bin Xu

doi:10.1016/j.scitotenv.2023.163297

Insight into mixed chlorine/chloramines conversion and associated water quality variability in drinking water distribution systems

Sci Total Environ. 2023 Jul 1:880:163297. doi: 10.1016/j.scitotenv.2023.163297. Epub 2023 Apr 5.

Authors

Renjie Pan¹, Tian-Yang Zhang¹, Zheng-Xiong Zheng¹, Jian Ai¹, Tao Ye², Heng-Xuan Zhao¹, Chen-Yan Hu³, Yu-Lin Tang¹, Jing-Jing Fan⁴, Bing Geng⁴, Bin Xu⁵

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Urban Water Supply, Water Saving and Water Environment Governance in the Yangtze River Delta of Ministry of Water Resources, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
² Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA.
³ College of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090, PR China.
⁴ Shanghai Chengtou Water (Group) Co. LTD, Shanghai 200002, PR China.
⁵ State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Urban Water Supply, Water Saving and Water Environment Governance in the Yangtze River Delta of Ministry of Water Resources, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China. Electronic address: tjwenwu@tongji.edu.cn.

PMID: 37028653
DOI: 10.1016/j.scitotenv.2023.163297

Abstract

Mixed chlorine/chloramines are common in drinking water distribution systems (DWDSs); however, their transformation and impact on chemical and microbial characteristics are not well understood. We systematically investigated water quality parameters associated with mixed chlorine/chloramine species conversion in 192 samples (including raw, finished, and tap water) collected throughout the year in a city in East China. Various chlorine/chloramine species (free chlorine, monochloramine [NH₂Cl], dichloramine [NHCl₂], and organic chloramines [OC]) were detected in both chlorinated and chloraminated DWDSs. NHCl₂ + OC increased with transport distance along the pipeline network. The maximum proportion of NHCl₂ + OC in over total chlorine in tap water reached 66 % and 38 % from chlorinated and chloraminated DWDSs, respectively. Both free chlorine and NH₂Cl showed a rapid decay in the water pipe systems, but NHCl₂ and OC were more persistent. Correlations between chlorine/chloramine species and physicochemical parameters were established. Models for predicting the sum of chloroform/TCM, bromodichloromethane/BDCM, chlorodibromomethane/CBDM, and bromoform/TBM (THM₄) (R² = 0.56) and haloacetic acids (HAAs) (R² = 0.65) exhibited greater accuracy based on machine learning tuned with chlorine/chloramine species, particularly NHCl₂ + OC. The predominant bacterial communities in mixed chlorine/chloramine systems were those resistant to chlorine or chloramine such as proteobacteria. NH₂Cl was the most significant explanatory factor (28.1 %) for the variation in microbial community assemblage in chloraminated DWDSs. Although residual free chlorine and NHCl₂ + OC, accounted for a smaller proportion of chlorine species in chloraminated DWDSs, they played an essential role (12.4 % and 9.1 %, respectively) in the microbial community structure.

Keywords: Disinfection byproducts; Drinking water distribution systems; Microbial community; Mixed chlorine/chloramine.

MeSH terms

Chloramines
Chlorine
Disinfection
Drinking Water*
Water Purification*
Water Quality

Substances

chloramine
Chloramines
Chlorine
Drinking Water