Accumulation of nitrite after reclaimed water recharge due to the disinfection byproduct chlorite. (April 2023)

• Record Type: Journal Article
• Authors: Wei, Ziyao; Lai, Yingnan; Li, Wenjing; Cui, Xiaochun; Zhou, Dandan; Zhang, Chaofan; Chen, Congli; Fang, Yuanping
• Is Part Of: Chemosphere. Volume 321(2023)
• Publication Date: 2023-04
• Subjects: Reclaimed water -- Disinfection byproduct -- Chlorite -- Nitrate -- Nitrite; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2023.138119
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Due to its toxicity, the disinfection byproduct chlorite in drinking water is strictly regulated to be ≤ 1.0 mg/L, but in reclaimed, non-drinking water chlorite is unregulated and rarely considered. However, chlorite is cytotoxic and has a high oxidation potential. Therefore, as reclaimed water infiltrates soil and groundwater, it may alter the soil environment and microbial community, which may affect the degradation of organic matter and the transformation of the N element. In this study, the effects of reclaimed water containing chlorite on soil microorganisms were investigated by simulating subsurface infiltration. It was found that chlorite improved the conversion of nitrate nitrogen to nitrite nitrogen, but inhibited further conversion of nitrite nitrogen. The nitrite nitrogen in the effluent reached 4.61 mg/L when chlorite was present, while only 0.16 mg/L was found in the control system. The chlorite produced obvious oxidative stress reactions in cells, inhibited the EPSs production, in which the contents of polysaccharides and proteins reduced by nearly 41% and 62%, respectively. Besides, chlorite resulted in the enrichment of efflux resistance genes in the microbial community, mainly adeF and cmlB1 . Self-protection against chlorite is achieved mainly using efflux pump related genes. Metagenomics data analysis showed that Delftia became the dominant genus when exposed to chlorite, with the greatest abundance at 17.9%. Chlorite also resulted in the upregulated expression of nar genes (by more than 149%) and downregulation of nir gene expression (by more than 62%). This study reveals the effects of the disinfection byproduct chlorite on a soil microecosystem, providing important information for the management and reuse of reclaimed water. Graphical abstract: Image 1 Highlights: ClO2 − promotes the conversion of nitrate to nitrite, but inhibits the further conversion of nitrite. ClO2 − changed the soil microbial community structure, and Delftia became the dominant genus. ClO2 − promoted the expression of nar genes and inhibited the expression of nir genes. The residue of ClO2 − increased the efflux resistance genes of the microbial system.