Characteristics of DOM in 14 AAO processes of municipal wastewater treatment plants
Graphical abstract
Introduction
Dissolved organic matter (DOM) is a highly heterogeneous mixture that can profoundly impact wastewater treatment systems (Cao et al., 2019; Cohen et al., 2014; Wang and Chen, 2018). DOM is the main substance removed during treatment and a limiting factor for wastewater reclamation and reuse applications (Phungsai et al., 2016; Qi et al., 2018; Wang and Chen, 2018) in areas where China experiences a shortage of water resources (Qu et al., 2019). Various biological treatment techniques to remove DOM in wastewater have been investigated (Liang et al., 2008; Kang et al., 2014).
DOM is inextricably related to various processes during wastewater treatment. DOM substances may impact coagulation efficiency (Rosario-Ortiz et al., 2007), disinfection by-product formation (Ike et al., 2020; Kimura and Ortega-Hernandez, 2019), membrane fouling (Jacquin et al., 2018; Ly and Hur, 2018) and microbial activity (Ishii and Boyer, 2012; Kwon et al., 2005) during treatment. The DOM's molecular weight distribution and hydrophobic/hydrophilic distribution reflect the source of the DOM, the transformation of the DOM (Mangal et al., 2020), and the biodegradability and biotoxicity of the DOM (Podgorski et al., 2018; Zhang et al., 2010) during wastewater treatment processes. For example, hydrophobic acids and hydrophobic neutral fractions of the secondary effluent were the key fractions related to anti-estrogenic activity that can enhance the potential ecological risk after the anaerobic-anoxic-oxic (AAO) process (Tang et al., 2013). A sub-fraction of hydrophobic acid (HOA) with MW less than 1 kDa can result in an increase in genotoxicity (Wu et al., 2010). The DOM's molecular weight distribution is an important index of wastewater treatability and can be used to evaluate the suitability of chemical, physical and biological processes to remove DOM in wastewater (Tran et al., 2015). The DOM's hydrophobic/hydrophilic distribution can affect the separation process such as interfacial adsorption and phase partitioning, and interaction between the DOM and surfaces/particles/colloids/solutes in wastewater (Tran et al., 2015; Xiao et al., 2016). Therefore, rapid monitoring of the MW distribution and hydrophobic/hydrophilic distribution of DOM would provide a comprehensive understanding of the state of wastewater treatment and will help to optimize the process operation to effectively remove DOM from wastewater. However, a comprehensive source of information is not available regarding DOM characteristics in typical municipal wastewater treatment plants (WWTPs).
It was inconvenient to measure the MW distribution and hydrophobic/hydrophilic distribution of DOM. Conventional measurement methods for MW distribution (such as adsorption column chromatographic fractionation) and hydrophobic/hydrophilic distribution (such as sequential ultrafiltration) are generally complicated and time-consuming (Leenheer and Croué, 2003; Xu and Guo, 2017; Xue et al., 2009). In comparison, excitation-emission matrix (EEM) fluorescence spectroscopy is a rapid and sensitive tool that can provide abundant fingerprinting information for DOM properties (Saadi et al., 2006; Cuss et al., 2016; Lee et al., 2019; Li et al., 2020b). The EEM technique has been applied as a monitoring tool in wastewater quality parameters such as biochemical oxygen demand and total organic carbon (TOC) (John Bridgeman et al., 2013, Carstea et al., 2016) and the removal of emerging contaminants (Sgroi et al., 2017). EEM fluorescence spectroscopy has even been applied to reveal the relationship between genotoxicity change and contaminant removal (Chai et al., 2018). It is worth further exploring if fluorescence spectroscopy could be used to indicate MW distribution and hydrophobic/hydrophilic distribution of DOM over a range of AAO processes that occur in WWTPs.
The AAO process constitutes the main municipal wastewater treatment technology in China (Zhang et al., 2016). This study investigated the characteristics of DOM in 14 municipal WWTPs using AAO processes located in different Chinese provinces (municipalities). Chemical composition, MW distribution and hydrophobic/hydrophilic distribution of DOM were analyzed. Multiple factor analysis (MFA) was conducted to reveal the effect of factors in the distribution of DOM in WWTP influent. Statistical analyses were employed to further explore if there are any statistical relationships between fluorescence spectral properties and MW distribution or hydrophobic/hydrophilic distribution of DOM in the AAO processes of WWTPs. The results may provide new clues for monitoring MW distribution or hydrophobic/hydrophilic distribution of DOM in wastewater treatment systems using fluorescence spectral properties.
Section snippets
Collection of DOM samples
The DOM samples were obtained from 14 municipal WWTPs with treatment capacities ranging from 100,000 to 1,200,000 m3/day. These WWTPs are located in 14 Chinese provinces (municipalities). Among them, seven WWTPs are in the north and the other seven WWTPs are in the south. The WWTPs influent primarily originated from domestic sewage. All the WWTPs are AAO treatment systems. The influent was obtained from the grille pool and the effluent was obtained from the secondary clarifier following the AAO
Chemical composition profiles of DOM in WWTPs influent and secondary effluent
HA, PN and PS were widely detected in 14 WWTPs, as shown in Fig. 1a. The TOC concentration of the DOM was from 18.26 ± 0.81 to 80.30 ± 0.47 mg/L in the influent. HA and PN were the dominant compositions of DOM in the influent, with median concentrations of 13.10 ± 0.37 and 13.09 ± 0.67 mg/L, respectively. The median concentration of PS was only 3.35 ± 0.55 mg/L (Table S2). In addition, HA, PN and PS accounted for 16.75–45.21%, 16.33–42.50% and 2.91–21.20% of the DOM (Fig. S1a). The major DOM
Conclusions
The chemical composition profiles, molecular weight and hydrophobic/hydrophilic distributions of DOM were investigated in the AAO systems of 14 municipal wastewater treatment plants. The median concentrations of the chemical composition of DOM decreased as HA > PN > PS in influent and secondary effluent. PN was the easiest to remove, followed by HA and PS. The DOM of MW <1 kDa and >10 kDa were the predominant fractions of DOM in influent and the MW <1 kDa was the largest group of DOM in the
Acknowledgements
This work was supported by the Jiangsu Natural Science Foundation of China (No. BK20180010), the National Science Foundation of China (No. 51978327, No. 21677071) and the National Water Pollution Control and Governance of Science and Technology Major Special (No. 2017ZX07202003).
References (83)
- et al.
Relating dissolved organic matter fluorescence and functional properties
Chemosphere
(2008) - et al.
Chemical differences of aquatic humic substances extracted by XAD-8 and DEAE-cellulose
J. Environ. Chem. Eng.
(2015) - et al.
New insights on the sludge fermentation liquid driven denitrification: evaluation of the system performance and effluent organic matter (EfOM)
Bioresour. Technol.
(2019) - et al.
Continuous fluorescence excitationeemission matrix monitoring of river organic matter
Water Res.
(2010) - et al.
Fluorescence spectroscopy for wastewater monitoring: a review
Water Res.
(2016) - et al.
A comparison of genotoxicity change in reclaimed wastewater from different disinfection processes
Chemosphere
(2018) - et al.
Size and XAD fractionations of trihalomethane precursors from soils
Chemosphere
(2006) - et al.
Fluorescent components of organic matter in wastewater: efficacy and selectivity of the water treatment
Water Res.
(2014) - et al.
Combining parallel factor analysis and machine learning for the classification of dissolved organic matter according to source using fluorescence signatures
Chemosphere
(2016) - et al.
Characterization and removal of dissolved organic matter in a vertical flow constructed wetland
Ecol. Eng.
(2014)
Dissolved organic matter in biologically treated sewage effluent (BTSE): characteristics and comparison
Desalination
Insight into the composition and degradation potential of dissolved organic matter with different hydrophobicity in landfill leachates
Chemosphere
Chemical composition of organic matters in domestic wastewater
Desalination
Characterisation of aquatic humic and non-humic matter with size-exclusion chromatography—organic carbon detection—organic nitrogen detection (LC-OCD-OND)
Water Res.
New insights into the size distribution of fluorescent dissolved organic matter in estuarine waters
Org. Geochem.
A comprehensive review of mathematical models developed for the estimation of organic disinfection byproducts
Chemosphere
New insight into fate and fouling behavior of bulk dissolved organic matter (DOM) in a full-scale membrane bioreactor for domestic wastewater treatment
J. Water Process Eng.
Influence of dissolved organic matter (DOM) characteristics on dissolved mercury (Hg) species composition in sediment porewater of lakes from southwest China
Water Res.
Effects of cimetidine on vaccine efficacy of orally administered live auxotrophic Edwardsiella tarda mutant in olive flounder (Paralichthys olivaceus)
Aquaculture
Formation mechanisms of disinfection byproducts: recent developments
Curr Opin Environ Sci Health
Natural organic matter fouling due to foulant-membrane physicochemical interactions
Desalination
A new molecular weight (MW) descriptor of dissolved organic matter to represent the MW-dependent distribution of aromatic condensation: insights from biodegradation and pyrene binding experiments
Sci. Total Environ.
Distribution and removal of fluorescent dissolved organic matter in 15 municipal wastewater treatment plants in China
Chemosphere
New advances in fluorescence excitation-emission matrix spectroscopy for the characterization of dissolved organic matter in drinking water treatment: a review
Chem. Eng. J.
Effect of solution chemistry on the fouling potential of dissolved organic matter in membrane bioreactor systems
J. Membr. Sci.
Biocides in the Yangtze River of China: spatiotemporal distribution, mass load and risk assessment
Environ. Pollut.
Further insight into the roles of the chemical composition of dissolved organic matter (DOM) on ultrafiltration membranes as revealed by multiple advanced DOM characterization tools
Chemosphere
Longterm monitoring of a full-scale municipal membrane bioreactor—characterisation of foulants and operational performance
J. Membr. Sci.
Effects of dissolved organic matter size fractions on trihalomethanes formation in MBR effluents during chlorine disinfection
Bioresour. Technol.
The characterization of dissolved organic matter in alkaline fermentation of sewage sludge with different pH for volatile fatty acids production
Water Res.
Linking molecular and optical properties of dissolved organic matter across a soil-water interface on Akimiski Island (Nunavut, Canada)
Sci. Total Environ.
Characterization and C-, N-disinfection byproduct formation of dissolved organic matter in MBR and anaerobic-anoxic-oxic (AAO) processes
Chem. Eng. J.
Dissolved effluent organic matter: characteristics and potential implications in wastewater treatment and reuse applications
Water Res.
Sample handling and data processing for fluorescent excitation-emission matrix (EEM) of dissolved organic matter (DOM)
Chemosphere
Molecular characterization of low molecular weight dissolved organic matter in water reclamation processes using Orbitrap mass spectrometry
Water Res.
Effect of ozonation on the characteristics of effluent organic matter fractions and subsequent associations with disinfection by-products formation
Sci. Total Environ.
A comprehensive structural evaluation of humic substances using several fluorescence techniques before and after ozonation. Part I: structural characterization of humic substances
Sci. Total Environ.
Characterization of dissolved organic matter in drinking water sources impacted by multiple tributaries
Water Res.
Monitoring of effluent DOM biodegradation using fluorescence, UV and DOC measurements
Chemosphere
Use of fluorescence EEM to monitor the removal of emerging contaminants in full scale wastewater treatment plants
J. Hazard. Mater.
Spectroscopic characterisation of dissolved organic matter changes in drinking water treatment: from PARAFAC analysis to online monitoring wavelengths
Water Res.
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Yufei Shi and Shengnan Li contributed equally to this work.