Electrochemical oxidation of simazine using BDD anodes: Degradation performance, microbial inactivation, and ecotoxicological outcomes

Electro-oxidation (EO) is a promising technology for the abatement of recalcitrant pesticides in water. We investigated the removal of simazine (SMZ) from aqueous solutions in a bench-scale BDD reactor, focusing on the effect of supporting electrolyte (NaCl, NaNO₃, NaClO₄), electrolyte concentration and applied current density. SMZ degradation was monitored by HPLC–DAD, and by-products were qualitatively identified to elucidate the main reaction pathway. Microbiological assays with Gram-positive and Gram-negative bacteria were used to assess the disinfection capacity of EO and post-EO treatment solution, while ecotoxicological endpoints in aquatic organisms were used to evaluate environmental safety. NaCl outperformed inert electrolytes, enabling up to ≈ 100 % SMZ removal within 180 min at 0.05–0.08 M and 20–40 A m⁻², with electrical energy consumption in the range 0.235–0.837 kWh per g of SMZ removed. HPLC–DAD analysis indicated the formation of N-dealkylated intermediates as major by-products. EO treatments achieved concurrent inactivation of microorganisms and a marked ecotoxic response both for producers and consumers. Overall, the results support BDD-based EO as a robust treatment approach for removing simazine and co-occurring microbes from contaminated water; however, the downstream mixture results in being harmful to the aquatic ecosystem.