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.

Dissolved organic matter (DOM) is the primary precursor that reacts with chlorine to form potentially carcinogenic/mutagenic disinfection byproducts (DBPs). The prime objective of this study was to compare the nature of DOM in samples collected from drinking water and wastewater treatment plants in western India and to relate their nature and concentration to trihalomethane (THM) formation. The effects of chlorine dose, bromide ion, contact time, and pH on THM formation were also studied. The surrogate parameters, such as UV absorbance at 254 nm and dissolved organic carbon (DOC) were monitored for each experiment to understand their correlation with THM formation in the selected water and wastewater systems. Fluorescence spectroscopy revealed that DOM in wastewater was dominated by protein-like components, while DOM in water samples consisted mostly of humic-like components, which exhibited greater THM formation potential. Fractionation of DOM into various fractions followed by reaction with chlorine revealed that the hydrophobic acid and neutral fractions of DOM were primarily responsible for THM formation. Thus, methods that target removing these fractions before chlorination would have maximum impact on reducing THM formation.