Enhanced coking wastewater advanced treatment by using particle electrodes excited persulfate in the three-dimensional electrocatalytic reactors

Abstract

Problems such as low concentration of organic pollutants in the biochemical effluent of coking wastewater and poor mass transfer efficiency have seriously affected the effectiveness of coking wastewater depth. Three-dimensional electrode oxidation processes (3DEOPs) are a very promising advanced oxidation process for wastewater treatment. Compared with the 3DEOPs, the treatment effect of coking wastewater was greatly improved by adding persulfate (PS) into the 3DEOPs. The experimental results showed that under the condition of adjusting the current density of 32 mA/cm2, adding 35 g of TSC6/BC particle electrodes and 2 mM PS, the COD concentration of the coking wastewater was reduced from 245.40 mg/L to 71.00 mg/L after 40 min of electrolysis, which has already met the discharge requirements. After 120 min of electrolysis, the UV254 of coking wastewater was reduced from 2.46 cm−1 to 0.35 cm−1, and the removal rate of COD and TOC in coking wastewater reached 93.44% and 78.19%, respectively. Compared with the use of BC and TiO2/BC, TS9/BC particle electrodes，the time for coking wastewater to meet the discharge standard was shortened by 20–30 min with TSC6/BC particle electrodes. Furthermore, the TSC6/BC particle electrodes improves the current efficiency and also saves energy of the system. The experimental results showed that both SO4−· and ·OH radicals in the 3DEOPs excited PS system play a very important roles to the degradation of organic pollutants in coking wastewater. This study provides theoretical guidance and technical support for the application of three-dimensional electrocatalytic technology for the treatment of actual coking wastewater.