Low formation of trihalomethanes in the disinfection of anaerobic effluent by electroactivated water.

This study investigated the effect of chlorinating an anaerobic reactor effluent with a high dosage of electroactivated water (EAW) and using the breakpoint strategy. The resulting effluent quality was evaluated based on the resolutions of the Brazilian Environmental Council. Disinfection by-products (DBPs) formation was measured as total trihalomethane (THM₄), i.e. the sum of chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM), which are the four major THM₄ species. The results for the formation of THM₄ were 217, 171 and 63 μg L^-1 at dosages of 55, 60, and 65 mg Cl₂ L^-1, respectively, which are even lower than the maximum value of 1 mg TCM L^-1, the only THM established in the Brazilian standards. The TCM, BDCM, DBCM and TBM concentrations determined in this study for those three dosages also comply with the discharge limits established for the classes II and III of surface wasters, by the Florida Department of Environmental Protection (USA).