Seasonal variation in fluorescence characteristics of dissolved organic matter in wastewater and identification of proteins through HRLC-MS/MS

In the present study, wastewater samples acquired from five wastewater treatment plants (WWTPs), located in western India were characterized using fluorescence spectroscopy, and resin-based fractionation was conducted to fractionate DOM into hydrophobic and hydrophilic base, acid, and neutral fractions. Among several fractions, the hydrophilic acid (HIA) and hydrophilic neutral (HIN) fractions were present in higher abundance (more than 50% of DOC) compared to the hydrophilic base (HIB) fraction in both influent and effluent wastewater stream obtained from WWTPs. Tryptophan-like and tyrosine-like substances were also abundant in the influent and effluent stream of WWTPs. Further, LC-MS/MS analysis could identify 235 and 288 DOM proteins in the influent and effluent stream of WWTP-1, respectively. These proteins revealed varying percentage of tryptophan and tyrosine residues. The tryptophan residues primarily contributed to protein-like fluorescence in wastewater. The proteins were further classified based on their role in biological processes, location in the cell, and molecular function. Among several proteins, Alzheimer's and Huntington disease biomarkers were identified at WWTP-1. Their presence in the surface water can serve as an early warning system for wastewater-based epidemiology.