Advanced electrocatalytic pre-treatment to improve the biodegradability of real wastewater from the electronics industry - A detailed investigation study.

For the first time, real effluents from the micro-electronics industry were treated by paired advanced electrocatalysis, combining electro-Fenton (EF) with anodic oxidation (AO). A detailed characterization of the effluents was performed, showing that isopropanol (IPA) and acetone were the main constituents of the wastewater. Both compounds were completely degraded during the first 120 min of treatment. By monitoring the degradation intermediates, an oxidation pathway was proposed, which includes short-chain carboxylic acids as the main end-organic compounds. While carbon brush served as the cathode, two anode materials were utilized: boron-doped diamond (BDD) and carbon-PTFE cloth (CC). Despite the lower mineralization efficiency showed by CC as compared to BDD (76.5% of TOC removal with CC vs 94.0% of TOC removal with BDD after 4 h), CC showed potential to increase the BOD5/COD ratio of the effluent that reached 0.7 after only 45 min (0.6 in 30 min with BDD). These results suggest that the electrolysis time could be kept short, improving the cost-effectiveness of the process, especially if CC is used. Overall, the results point out the suitability of advanced electrocatalysis to treat real electronics wastewater with low energy requirements, short treatment times and cost-effective electrode materials.