Effect of UV irradiation on iodinated trihalomethane formation during post-chloramination

Ying Xia; Yi-Li Lin; Bin Xu; Chen-Yan Hu; Ze-Chen Gao; Yu-Lin Tang; Wen-Hai Chu; Tong-Cheng Cao; Nai-Yun Gao

doi:10.1016/j.watres.2018.09.045

Effect of UV irradiation on iodinated trihalomethane formation during post-chloramination

Water Res. 2018 Dec 15:147:101-111. doi: 10.1016/j.watres.2018.09.045. Epub 2018 Sep 27.

Authors

Ying Xia¹, Yi-Li Lin², Bin Xu³, Chen-Yan Hu⁴, Ze-Chen Gao⁵, Yu-Lin Tang⁵, Wen-Hai Chu¹, Tong-Cheng Cao⁶, Nai-Yun Gao⁵

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze Water Environment, Ministry of Education, 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 Safety, Health and Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, 824, Taiwan, ROC.
³ State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze Water Environment, Ministry of Education, 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.
⁴ College of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai, 200090, PR China.
⁵ State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China.
⁶ School of Chemical Science and Engineering, Tongji University, Shanghai, 200092, PR China.

PMID: 30300780
DOI: 10.1016/j.watres.2018.09.045

Abstract

Ultraviolet (UV) irradiation has been widely used in drinking water treatment processes, but its influence on the formation of disinfection by-products (DBPs), especially the emerging iodinated trihalomethanes (I-THMs) during post-chloramination remains unclear. This study evaluated the impact of low pressure (LP) UV treatment on the formation of I-THMs during post-chloramination through two pathways. The first pathway is through the transition of DOM structure and composition during UV-chloramination, resulting significant increase of I-THM formation with increasing UV dosage in different dissolved organic matter (DOM)-containing water (49.7%-90.5% at 1160 mJ/cm²). With the application of excitation emission matrix-parallel factor analysis (EEM-PARAFAC), we found that I-THM formation in UV-chloraminated water correlated well with two ratios of three PARAFAC humic-like components (C3/C2 and C1/C2, R² = 0.958-1.000), suggesting that the ratios of fluorescent components can be used as reliable indicators for I-THM formation. Moreover, the shift in these fluorescent components is crucial for I-THM formation during UV-chloramination. Another pathway for UV irradiation to affect I-THM formation during post-chloramination is through the transformation of iodine species. Large amounts of reactive iodine species (HOI/I₂ and I₃^-) can be generated directly in the mixed iodine system by UV light, leading to the enhancement of iodine utilization factor (IUF) (up to 0.040) after post-chloramination. These results suggest that UV application to DOM-containing water may induce changes in organic precursors and iodine species so as to enhance I-THM formation during post-chloramination.

Keywords: Chloramination; Dissolved organic matter (DOM); Fluorescence spectroscopy; Iodinated trihalomethanes (I-THMs); Iodine utilization factor (IUF); Ultraviolet (UV) irradiation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Disinfection
Trihalomethanes
Ultraviolet Rays
Water Pollutants, Chemical*
Water Purification*

Substances

Trihalomethanes
Water Pollutants, Chemical