Formation of assimilable organic carbon (AOC) during drinking water disinfection: A microbiological prospect of disinfection byproducts

Guocheng Huang; Tsz-Wai Ng; Huan Chen; Alex T Chow; Shengwei Liu; Po Keung Wong

doi:10.1016/j.envint.2019.105389

Formation of assimilable organic carbon (AOC) during drinking water disinfection: A microbiological prospect of disinfection byproducts

Environ Int. 2020 Feb:135:105389. doi: 10.1016/j.envint.2019.105389. Epub 2019 Dec 12.

Authors

Guocheng Huang¹, Tsz-Wai Ng², Huan Chen³, Alex T Chow⁴, Shengwei Liu⁵, Po Keung Wong⁶

Affiliations

¹ School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China; School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong Special Administrative Region.
² School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong Special Administrative Region.
³ Baruch Institute of Coastal Ecology & Forest Science, Clemson University, Georgetown, SC, USA.
⁴ Baruch Institute of Coastal Ecology & Forest Science, Clemson University, Georgetown, SC, USA. Electronic address: achow@clemson.edu.
⁵ School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China. Electronic address: liushw6@mail.sysu.edu.cn.
⁶ School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong Special Administrative Region; Institute of Environmental Health and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China. Electronic address: pkwong@cuhk.edu.hk.

PMID: 31838266
DOI: 10.1016/j.envint.2019.105389

Abstract

Disinfection processes might alter the chemical structure of biological recalcitrant natural organic matter (NOM) in source water to form assimilable organic carbon (AOC), which can be readily utilized by microbes for growth. However, AOC has not been classified as disinfection byproducts (DBPs) before and little is known about the chemical and structural nature of AOC. This study, for the first time, considers the disinfection-induced AOC as DBPs from a microbiological perspective. The AOC formation by three types of disinfection processes, i.e., chlorination, UVC irradiation (254 nm) and photocatalysis represented by TiO₂-UVA in drinking water containing two reference NOM materials of Suwannee River and Nordic Reservoir (SRNOM and NRNOM, respectively) were comparatively benchmarked using Pseudomonas aeruginosa as inoculum. Results showed that chlorination caused a substantial increase in AOC content, whereas TiO₂-UVA led to a moderate increase in AOC content and UVC rendered the AOC content unchanged, independent of the types of NOM. Molecular weight indicated by spectral slope ratio and fluorescence fingerprint were found to not provide critical information about the AOC formation potential. FTIR and FT-ICR-MS results indicated that the AOC formation by chlorination was attributed to the oxidation and chlorine substitution on aromatic molecules to form molecules with carboxylic- and alcohol- functionalities, as well as chlorinated aromatics. These molecules could be metabolized and assimilated by Pseudomonas species by a catechol pathway. The results obtained in this study can provide valuable insight regarding the selection of proper technologies for disinfection to prevent microbial growth/regrowth in the distributing system and is intended to encourage more thinking and research on AOC as a new prospect of DBPs during disinfection of drinking water.

Keywords: Assimilable organic carbon; Disinfection byproducts; Drinking water; Microbial regrowth; Natural organic matter.

Publication types

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

MeSH terms

Carbon
Chlorine
Disinfectants
Disinfection
Drinking Water
Halogenation
Water Pollutants, Chemical*
Water Purification*

Substances

Disinfectants
Drinking Water
Water Pollutants, Chemical
Chlorine
Carbon