Azo Dye Decolorization in Sole Biocatalyzed Electrolysis System (BES) and Coupled with Anaerobic Sequencing Batch Reactor (ASBR-BES) in Operation with Ideal Synthetic Wastewater and Domestic Wastewater

In practice, various waste streams may be available to drive biocatalyzed electrolysis systems (BESs) for azo dyes decolorization, which can affect how BES is employed to achieve superior performance. This work examined the performance of BES and coupling it with an anaerobic sequencing batch reactor (ASBR-BES) in operation with ideal synthetic wastewater (SW) and domestic wastewater (DW) to remove acid orange 7 (AO7). Within 10 h, ASBR-BES-SW showed an acceptable AO7 removal efficiency (94% ± 0.6%) higher than BES-SW. However, in applying DW, BES achieved 5.3% higher decolorization efficiency compared to ASBR-BES (79.3% ± 0.7%) in 26 h, which was enhanced to 95.5% ± 0.4% by reducing the electrode spacing to 1 cm. Higher reductant usage ratio and more residual chemical oxygen demand were achieved in SW than DW. Coulombic efficiencies on AO7 reduction and COD oxidation were evaluated to investigate the contribution of removal processes. Also, variations of electrical conductivity, temperature, pH, and current density during a cycle were examined.