A pilot-scale three-dimensional electrochemical reactor combined with anaerobic-anoxic-oxic system for advanced treatment of coking wastewater

Coking wastewater is highly concentrated and extremely toxic, greatly challenging the treatment technologies. Conventional biological technology such as anaerobic-anoxic-oxic (A2O) system is inefficient, since various biological reactions are inhibited by toxicants in coking wastewater. In this work, a pilot-scale three-dimensional electrochemical reactor (3DER) is integrated into the A2O system as a pretreatment unit to improve the treatment efficiency of coking wastewater. The results indicate that 3DER pretreatment increased the biodegradability of coking wastewater, promoting the degradation of coking wastewater in A2O system. The integrated 3DER-A2O system can remove 94.4% of COD and 76.2% of TN from coking wastewater, and the energy consumption was only 0.22 kWh/kg COD and 4.69 kWh/kg TN. The components of coking wastewater were significantly simplified and the acute toxicity was reduced from 99% to 12% after the treatment. The integrated 3DER-A2O system provides a new solution for coking wastewater treatment, showing a promising application potential.