Molecular insights into formation of nitrogenous disinfection byproducts from algal organic matter in UV-LEDs/chlorine process based on FT-ICR analysis

• Published in: The Science of the total environment Vol. 812; p. 152457
• Main Authors: Wu, Yuwei, Sheng, Da, Wu, Yangtao, Sun, Julong, Bu, Lingjun, Zhu, Shumin, Zhou, Shiqing
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.03.2022
• Subjects: AOM; Chlorine - analysis; Disinfectants; Disinfection; Elemental composition; Halogenation; N-DBPs; Nitrogen; Precursors; Theoretical toxicity; Water Pollutants, Chemical - analysis; Water Purification; Elemental composition; Theoretical toxicity; N-DBPs; Precursors; AOM
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.152457

Eutrophication is a globally concerned issue, which brings algal cells and algal organic matter (AOM) into drinking water treatment plants. AOM is an important branch of nitrogenous disinfection byproduct (N-DBP) precursors. The variation of AOM composition in UV-LEDs/chlorine process, and its relationship with N-DBP formation still remain much uncertainty. Herein, we used fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to investigate AOM transformation in UV-LEDs/chlorine process, with UV285 and UV365 as light source, and screen for typical precursors of N-DBPs. We found that more nitrogen-containing compounds were generated after UV-LEDs/chlorine process, leading to the larger formation of N-DBPs in postchlorination. Compounds such as lignin, proteins, and amino sugars tends to be oxidized by reactive species in UV-LEDs/chlorine process. Further, compounds with higher O/C and higher weighted average double bond equivalence (DBEw) are easier to form N-DBPs, including dichloroacetonitrile and trichloronitromethane. Also, influence factors including pH, UV fluence, post-chlorination time and bromide concentration on N-DBP formation were evaluated. The results show that N-DBP formation generally followed the order of UV285/chlorine-postchlorination, UV365/chlorine-postchlorination, and direct chlorination. Our study provides comprehensive information on N-DBP formation from AOM in UV-LEDs/chlorine-postchlorination from molecular levels. [Display omitted] •UV-LEDs/chlorine pretreatments enhanced the cytotoxicity of formed N-DBPs.•More N-containing compounds formed after pretreated by UV-LEDs/chlorine.•Compounds with higher O/C and DBEw were easier to form N-DBPs.•The N-DBP yields followed in the order of 285 nm > 365 nm > direct chlorination.