Water recycling public toilets based on onsite electrochemical wastewater treatment

Abstract

The long-term performance of an anaerobic bioreactor combined with electrochemical oxidation and integrated into a self-contained public bathroom under daily use was investigated over 14 months in Coimbatore (Tamil Nadu, India). With varying daily number of users and across all seasons, the electrochemical treatment of the bioreactor effluent consistently generated a highly chlorinated (>400 mg Cl₂ per L) and clear effluent that was negative to a fecal coliform assay. During 8 months of testing under water recycling conditions, the treatment maintained its performance for disinfection, as well as solid and nitrogen removal, due to breakpoint chlorination; however, the COD removal capacity of the system was slightly reduced. The strongly oxidizing condition of this electrochemical based disinfection raised the concern of generation of toxic disinfection byproducts (DPBs). This study also examined the formation of chloroform and haloacetic acid DBPs under non-recycling and recycling conditions.