BackgroundElectrochemical oxidation has attracted wide attention in wastewater treatment because of its strong oxidation performance and ease of control. This work investigated the feasibility of electrochemical treatment using a Ti/RuO2-IrO2 anode as an advanced treatment of coking wastewater. The influential operating factors including current density (9.6-108.2mAcm(-2)) and electrode gap (0.5-2.5cm) were evaluated. ResultsThe current density and electrodes gap had significant effects on COD and NH4+-N removal and the energy consumption. The degradation of COD and NH4+-N followed pseudo-first-order kinetics. In most experiments, high levels of NH4+-N removal (NH4+-N removal ratio>95%) was achieved along with moderate mineralization (COD removal ratio: 60-80%). COD (178.0-285.0mgL(-1)) and NH4+-N (55.0-76.0mgL(-1)) were degraded by 62% and 96%, respectively, at the optimum conditions (electrode gap: 0.5cm, current density: 15.6mAcm(-2)) after 60min treatment. Under this optimal condition, the corresponding energy consumption was 8.60 kWh m(-3) for effluent meeting the discharge standards. Furthermore, gas chromatography-mass spectrometry (GC-MS) analysis indicated that this technique could be employed to eliminate bio-refractory and toxic compounds such as phenanthrene, indole, quinoline and pyrimidine in coking wastewater. ConclusionTi/RuO2-IrO2 anode systems were confirmed to be effective in advanced treatment of biologically pretreated coking wastewater. (c) 2012 Society of Chemical Industry