Experiment study on the separation of bituminous coal adsorption and the synergism of ultraviolet and electrochemistry in the pretreatment of coal chemical wastewater

[Display omitted] •Adsorption pretreatment was beneficial to a subsequent oxidation treatment.•Electrochemistry and UV had a synergistic effect in coking wastewater treatment.•Polycyclic aromatic hydrocarbons were preferentially adsorbed.•Fluorescence detection can be used as an effective on-line monitoring method.•The active chlorine could be regulated by operating parameters. Although clean coal utilization has attracted much attention, it is challenging to treat coal chemical wastewater. In this work, the coking wastewater was treated by bituminous coal adsorption and composite advanced oxidation technology. The effect of adsorption on organic separation and the synergy between UV and electrochemistry were investigated. The results indicated that the removal of total organic carbon (TOC), chroma, and UV254 by bituminous coal adsorption was effective. And polycyclic aromatic hydrocarbons were preferentially adsorbed, followed by phenols and aliphatic hydrocarbons. After bituminous coal adsorption and electrochemical/UV/H2O2 treatment, the TOC of coking wastewater decreased by 68.92%, which was better than adsorption/electrochemical and adsorption/UV. Through excitation-emission matrix (EEM) and gas chromatography-mass spectrometry (GC–MS) analysis, the improvement of biodegradability was attributed to the reduction of polycyclic aromatic hydrocarbons, long-chain alkane, and nitrogen heterocyclic compounds in the coking wastewater. UV photocatalysis and electrochemical had synergistic effects on the degradation of polycyclic aromatic hydrocarbons. Besides, the active chlorine could be regulated by adjusting the current density and the dosage of hydrogen peroxide.