Mitigation of micropollutant toxicity in treated wastewater using the H2O2/S2O82-/UVC process: An ecotoxicological perspective for agricultural reuse.

Advanced oxidation processes can efficiently degrade organic micropollutants in wastewater. However, chemical assessment alone does not ensure that treated effluents are biologically compatible for reuse, as residual contaminants and transformation products may have toxic effects. Thus, this study evaluated the efficiency of the previously optimized H2O2/S2O82‒/UVC process for mitigating the ecotoxicological effects of municipal wastewater enriched with colchicine, nitazoxanide, and sulfamethoxazole, considering its potential application for agricultural reuse. The approach was based on multiple ecotoxicological parameters at different biological levels: oxidative stress in Eisenia andrei, phytotoxicity in Lactuca sativa, cytotoxicity and genotoxicity in Allium cepa, and growth inhibition of environmentally relevant microorganisms (Azospirillum brasilense and Saccharomyces cerevisiae). The microcontaminant-enriched effluent exhibited substantial genotoxicity (21%) and severe phytotoxicity, highlighting the risks of reusing effluent without advanced treatment. The H2O2/S2O82‒/UVC process significantly reduced residual toxicity, lowering genotoxicity to 6% and increasing the plant growth index to values above 80%. This process did not induce cytotoxic effects or adversely affect beneficial microorganisms. These results suggest that the process can reduce the toxicity and biological impacts of microcontaminants, which could mitigate the ecotoxicological risks of wastewater intended for non-potable reuse, including in agriculture.