Microbial Transformation of Dissolved Organic Sulfur during the Oxic Process in 47 Full-Scale Municipal Wastewater Treatment Plants

Abstract

Dissolved organic sulfur (DOS) is a significant part of effluent organic matter of wastewater treatment plants (WWTPs) and poses a potential ecological risk for receiving waters. However, the oxic process is a critical unit of biological wastewater treatment for microorganisms performing organic matter removal, wherein DOS transformation and its mechanism are poorly understood. This study investigated the transformation of DOS during the oxic process in 47 full-scale municipal WWTPs across China from molecular and microbial aspects. Surprisingly, evident differences in DOS variations (ΔDOS) separated sampled WWTPs into two groups: 28 WWTPs with decreased DOS concentrations in effluents (ΔDOS < 0) and 19 WWTPs with increased DOS (ΔDOS > 0). These two groups also presented differences in DOS molecular characteristics: higher nitrogen/carbon (N/C) ratios (0.030) and more peptide-like DOS (8.2%) occurred in WWTPs with ΔDOS > 0, implying that peptide-like DOS generated from microbes contributed to increased DOS in effluents. Specific microbe–DOS correlations (Spearman correlation, p < 0.05) indicated that increased effluent DOS might be explained by peptide-like DOS preferentially being produced during copiotrophic bacterial growth and accumulating due to less active cofactor metabolisms. Considering the potential environmental issues accompanying DOS discharge from WWTPs with ΔDOS > 0, our study highlights the importance of focusing on the transformation and control of DOS in the oxic process.

Comprehensive Characterization of the Transformation of Wastewater Effluent via Advanced Oxidation Processes Using Nontarget Mass Spectrometric Analysis

“…Amine groups were identified as an important reaction site for organic compounds in wastewater effluent, with 318 and 429 related links in the UV/H 2 O 2 and UV/PDS processes, respectively. Moreover, sulfur-containing compounds are reportedly important components in wastewater effluent, and sulfur reactions were found to account for approximately 4% of total linkages in the two AOPs. The presence of nitration links (81 links in UV/H 2 O 2 , 102 links in UV/PDS) implied participation of NO 2 • in the transformation of organic compounds, as reaction of NO 2 • is the primary pathway to nitration .…”

Carbon Source in Tertiary Denitrification Regulates Dissolved Organic Nitrogen in Wastewater Effluent

“…Path analysis by partial least-squares path modeling (PLS–PM) was performed to identify qualitative and quantitative response relationships among carbon sources, microorganisms, DON components, and effluent DON concentration, which were analyzed using the plspm package in the R 4.2.2 environment. Both the path coefficients and loadings were represented by r. The manifest variables with loadings greater than 0.7 have a better explanation of their corresponding latent variables . PLS–PM was conducted as the previous study, and a detailed description is shown in Text S6 .…”

“…Both the path coefficients and loadings were represented by r. The manifest variables with loadings greater than 0.7 have a better explanation of their corresponding latent variables. 51 PLS− PM was conducted as the previous study, and a detailed description is shown in Text S6. 33 The co-occurrence network of significant microorganism-produced DON and microorganism−microorganism interactions was visualized by Gephi 0.9.2.…”

Molecular characterization of coastal seawater dissolved organic matter by ultrahigh-resolution mass spectrometry: a photochemical study of the Tokyo Bay, Japan

“…DOM is a ubiquitous component of natural coastal seawaters and can be an essential precursor for natural organohalogen compounds (Liu et al 2023b;Méndez-Díaz et al 2014). The natural coastal seawater is highly complex and chemically diverse and is highly susceptible to anthropogenic activities, such as the extensive use of detergents, surfactants, and sulfa drugs (Boreen et al 2005;Guo et al 2021;Liu et al 2023a;Wang et al 2018b). Our newly proposed index, DBE-0.5O, is of great importance in accurately revealing the unsaturation degree of the carbon skeleton in DOM molecules for natural and engineered systems.…”

“…For example, the proportion of CHOS compounds in the DOM from the natural coastal seawater of Tokyo Bay was higher than that in the natural freshwater upstream of Tama River (Fu et al 2020a), suggesting that the coastal seawater quality was susceptible to anthropogenic activities. Most S-containing substances are derived from various productive activities, such as the extensive use of surfactants (Liu et al 2023a). The S-containing DOM compounds in wastewater have a potential endocrinedisrupting effect, consequently reducing the water quality and promoting the production of neurotoxic methylmercury (Ksionzek et al 2016;Michael et al 2015).…”