Electrochemical disinfection and removal of ammonia nitrogen for the reclamation of wastewater treatment plant effluent.

Residual ammonia and pathogenic microorganisms restrict the reclamation and reuse of wastewater treatment plant (WWTP) effluent. An electrochemical system was developed for the simultaneous removal of ammonia and disinfection of actual WWTP effluent. The performance of the electrochemical process on synthetic wastewater at different chloride ion concentrations was also investigated. Results demonstrated that the optimal chloride concentration for ammonia and Escherichia coli (E. coli) removal was 250 mg/L. Successful disinfection of E. coli in actual effluent was achieved at 0.072 Ah/L, but the inverse S-type inactivation curve indicated that there was a competitive consumption of strong oxidants and chloramines working as another disinfectant. A higher electric charge (0.58 Ah/L) was required to simultaneously reduce E. coli and ammonia to levels that meet the reclamation requirements for WWTP effluent. At this electric charge, no trihalomethane, chlorate, or perchlorate in the system was observed, indicating the biological safety of this process. These results demonstrate the potential of this electrochemical process as a tertiary wastewater treatment process for WWTP effluent reclamation purposes.