A novel stacked flow-through electro-Fenton reactor as decentralized system for the simultaneous removal of pollutants (COD, NH3-N and TP) and disinfection from domestic sewage containing chloride ions

Abstract

Cost-effective treatment of domestic sewage from the scattered and remote residential areas is a big challenge for widely used conventional biotechnical treatment. A novel stacked flow-through electro-Fenton (EF) reactor was firstly constructed using the modified graphite felt cathodes and DSA mesh anodes in this work, and attempted to remove multiple pollutants from domestic sewage. The proportion of dead space was very low and the short circuit phenomenon was not obvious in this designed reactor based on the hydraulic characterization analysis. The influence of important parameters such as initial pH, applied voltage and flow rate were investigated. The COD could be effectively removed from domestic sewage without adding electrolyte and adjusting initial pH by this novel EF reactor, and the effluent COD (in the range of 47–56 mg/L) could meet the prescribed discharge standard in China with a very low electrical energy consumption of 0.97 kWh/m3 under the applied voltage of 2.5 V and flow rate of 30 mL/min. Moreover, the desirable performance in the disinfection and removal of TP (97.6%), NH3-N (90.8%) and suspended solids (nearly 100%) could also be simultaneously obtained by this EF reactor without additional treatment process, and the possible process mechanism of COD, TP and NH3-N removal was further explored. Besides, the effluent met the China's urban miscellaneous water quality standards and could be reused for urban greening, road cleaning or flushing toilets. Therefore, the above analysis demonstrated that this novel stacked flow-through EF reactor could be used as an energy-efficient decentralized system for the treatment and reuse of domestic sewage.