A coupled system of flow-through electro-Fenton and electrosorption processes for the efficient treatment of high-salinity organic wastewater

Abstract

The traditional high-salinity organic wastewater treatment process is cumbersome and costly, and involves an independent process for removing pollutants and salinity. A flow-through coupled system of electro-Fenton and electrosorption processes was designed in this work. The simultaneous purification and desalination of high concentration wastewater were effectively achieved through the cooperation of various electrochemical reactions, which avoids the complex processes of desalination and dilution in advance when treating high-salinity organic wastewater, and the removal performance was improved. The influence of key parameters, including voltage, initial pH, plate spacing, H2O2 concentration, and flow rate, were systematically investigated. The findings show that actual wastewater passing through the coupled system promptly turns to clean water with significantly decreased COD, TN, and salinity, with removal efficiencies reaching 96.5%, 98.2%, and 46.2%, respectively, under the optimal conditions (voltage intensity 1.5 V, initial pH 4, plate spacing 1 cm, flow rate 40 mL/min, H2O2 concentration 50 mM). The reaction mechanism study suggested that both the Fenton reaction, direct electron transfer, and indirect oxidation by active chlorine contributed to the removal of COD and TN, while the decrease in salinity mainly occurred in the process of electrosorption. Moreover, the regeneration of the ACF and the operational stability of the coupled system were good after five cycles. The economic analysis indicated that the cost of the flow-through coupled system was only $1.18/m3, which has important benefits.