Oxidation of benzalkonium chloride in aqueous solution by S2O82−/Fe2+ process: Degradation pathway, and toxicity evaluation

The present study is to investigate the treatment of a disinfectants wastewater containing benzalkonium chloride (BAC) by S 2 O 8 2− /Fe 2+ process and microbial fuel cell (MFC) system was applied as bio-sensor for the toxicity test of degradation products. The operating oxidation conditions have been optimized. The optimal condition for the degradation of BAC were: pH   =   5.0, [S 2 O 8 2− ]/[ Fe 2+ ]   =   1:2, the removal rate of BAC reaches 91.45%, and the COD removal efficiency was 52.46% after 60   min. The degradation intermediates were identified by GC–MS and the degradation pathway of BAC was proposed. The toxicity and biodegradability of intermediates of BAC after being treated by S 2 O 8 2− /Fe 2+ oxidation was analyzed by MFC system. The generated power of MFC system was closely related to the initial concentration of BAC. The voltage output and maximal power density were increased from 25.42   mV and 1.01   mW/m 2 to 37.80   mV and 12.13   mW/m 2 after 100   mg L −1 BAC was treated by S 2 O 8 2− /Fe 2+ oxidation process. These results indicated that the S 2 O 8 2− /Fe 2+ oxidation shows positive effect for enhancing the biodegradability of intermediates.