Advanced oxidation of Trihalomethane (THMs) precursors and season-wise multi-pathway human carcinogenic risk assessment in Indian drinking water supplies

Advanced oxidation processes (AOPs) in water treatment industries can simultaneously offer disinfection and eradicate organic contaminants. The present work examined the direct exposure impact of various oxidative (UV, O-3, and H2O2) and their eclectic combinations (UV/O-3, H2O2/O-3, and UV/H2O2) for the abolition of Trihalomethane (THMs) precursors. The application of the Fenton process proved to be the most effective technique for reducing TOC (85.23%) and UV254 (91.11%) than other used AOPs. Higher removal of THMs precursors found in the Fenton process may be attributed to the higher degradation potential of hydroxyl radical generated from this process than other AOPs. The deformed ferrous iron salts (Fe2+) in the Fenton reagent catalyzed the hydrogen peroxide (H2O2) and produced highly reactive radicals. Seasonal probabilistic lifetime cancer and non-cancer risks of THMs in males and females were also investigated in the drinking water supplies of five major cities in India. Comparative risk analysis through different pathways revealed significant risk from oral ingestion (99%), followed by inhalation exposure (0.77%) and dermal absorption (0.0 02%), where females were found at higher risk of cancer. Sensitivity analysis using a radar plot was also performed to identify the most influential parameter affecting the total risk of cancer. The Risk value of chloroform (CF) was highest among the THMs compound in all the WTPs for both seasons. Seasonal risk assessment revealed a higher risk of cancer in the pre-monsoon season. (c) 2022 Published by Elsevier Ltd on behalf of Institution of Chemical Engineers.

Automated summary

This study examined the effectiveness of various oxidation processes in removing Trihalomethane (THMs) precursors in water treatment and found that the Fenton process was the most effective technique. The Fenton process showed higher degradation potential and achieved significant reductions in total organic carbon (TOC) and UV254. Additionally, the study investigated the cancer and non-cancer risks associated with THMs in drinking water supplies in major Indian cities and found that oral ingestion presented the highest risk, with females at higher risk of cancer. Seasonal risk assessment also revealed a higher cancer risk in the pre-monsoon season.