Sequential ClO2-UV/chlorine process for micropollutant removal and disinfection byproduct control

Mengge Fan; Xin Yang; Qingqing Kong; Yu Lei; Xinran Zhang; Ehsan Aghdam; Ran Yin; Chii Shang

doi:10.1016/j.scitotenv.2021.150354

Sequential ClO₂-UV/chlorine process for micropollutant removal and disinfection byproduct control

Sci Total Environ. 2022 Feb 1;806(Pt 1):150354. doi: 10.1016/j.scitotenv.2021.150354. Epub 2021 Sep 16.

Authors

Mengge Fan¹, Xin Yang¹, Qingqing Kong¹, Yu Lei¹, Xinran Zhang², Ehsan Aghdam³, Ran Yin⁴, Chii Shang⁵

Affiliations

¹ School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, China.
² School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, China. Electronic address: zhangxinr@mail.sysu.edu.cn.
³ Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
⁴ Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China. Electronic address: ryin@connect.ust.hk.
⁵ Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Hong Kong Branch of Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.

PMID: 34560452
DOI: 10.1016/j.scitotenv.2021.150354

Abstract

This study systematically revealed the feasibility of the sequential ClO₂-UV/chlorine process for micropollutant removal and disinfection byproduct (DBP) control. The results demonstrated that the sequential ClO₂-UV/chlorine process was effective for the removal of 12 micropollutants. ClO₂ pre-treatment reduced the formation of disinfect byproducts (DBPs) in the UV/chlorine process. Compared to the UV/chlorine process, ClO₂ pre-treatment (1.0 mg L^-1) decreased the formation of the 6 DBPs by 25.1-72.2%; and decreased the formation potential of the 6 DBPs by 13.9-51.8%. Moreover, ClO₂ pre-treatment reduced the concentration of total organic chlorine by 19.8%. ClO₂ pre-treatment affected the UV/chlorine process in different ways. Firstly, ClO₂ pre-treatment generated chlorite, which dominantly served as a scavenger of chlorine radical (Cl) and hydroxyl radical (HO). Secondly, ClO₂ pre-treatment decreased the reactivity of natural organic matter (NOM) towards radicals. Finally, ClO₂ pre-treatment altered the properties of NOM, in terms of reducing the electron-donating capacity and aromaticity of NOM (SUVA₂₅₄), and slightly reducing the average molecular weight of NOM. Overall, ClO₂ pre-treatment effectively controlled the formation of DBPs in the UV/chlorine process. This study confirmed the sequential ClO₂-UV/chlorine process was an alternative strategy to balancing the micropollutant removal and DBP control.

Keywords: ClO(2); Disinfection byproducts (DBPs); Micropollutants; Natural organic matter; UV/chlorine process.

MeSH terms

Chlorine
Disinfection
Halogenation
Hydroxyl Radical
Water Pollutants, Chemical* / analysis
Water Purification*

Substances

Water Pollutants, Chemical
Hydroxyl Radical
Chlorine