Pretreatment of hypersaline and high-organic wastewater with a three-dimensional electrocatalytic system: a pilot-scale study

Abstract

The three-dimensional electrocatalytic oxidation (3DEO) is a promising electrochemical system in the treatment of refractory wastewater, but still far from large-scale applications. In this work, we prepared 146.5 Kg Ti-Sn-Sb@γ-Al2O3 particle electrodes to construct a 3DEO system for the pretreatment of hypersaline and high-organic wastewater in an industrial park sewage plant, with activated carbon particle electrodes as a comparison. The average COD removal rates of Ti-Sn-Sb@γ-Al2O3 and activated carbon-based 3DEO systems were 24.43 and 48.73%, respectively, and the energy consumption of the two 3DEO systems were 102.8 and 31.4 kWh/Kg COD, respectively. However, compared to the negligible enhancement of wastewater biodegradability in the activated carbon 3DEO system, the Ti-Sn-Sb@γ-Al2O3 3DEO system greatly improved the biochemical index (B/C) from 0.021 to 0.166 (by 690.5%). Due to its superior catalytic capacity, Ti-Sn-Sb@γ-Al2O3 outperforms activated carbon in improving biodegradability as the latter relies mainly on adsorption. The results of this work provide a 3DEO engineering practice experience on the pretreatment of hypersaline and high-organic wastewater. HIGHLIGHTS A three-dimensional electrocatalytic oxidation (3DEO) system was established to pretreat hypersaline and high-organic wastewater.; Ti-Sn-Sb@γ-Al2O3 3DEO shows good ability to improve biodegradability.; Activated carbon 3DEO system shows higher but gradually decreasing COD removal.; Energy consumption is low in the pilot-scale pretreatment process.; Ti-Sn-Sb@γ-Al2O3 electrodes retain major active species in long-term use.;

Keywords

• biodegradability
• electrocatalytic oxidation
• energy consumption
• industrial wastewater
• particle electrodes