Decolorization of Azo Dyes in Dual-Chamber Bioelectrochemical Systems Seeding with Enriched Inoculum

Abstract

Azo dyes pollution has attracted a major environmental concern due to their color and toxicity. In this study, we investigated a biocatalyzed electrolysis system (BES) with a bio-cathode seeding with enriched inoculum for the decolorization of a model azo dye, alizarin yellow R (AYR). The bio-cathode was inoculated with AYR autotrophic biodegrading consortium. Batch test results showed that the decolorization efficiency (DE) of AYR (100mg/L) reached to 93.2% within 58 hours with 0.5V power supplied and NaHCO3 (840 mg/L) as sole carbon source. Lower DEs of 83.5% and 70.7% were respectively observed in abiotic cathode BESs and bio-cathode BESs inoculated with mixed sludge. The result indicated that the enriched inoculum had a significant effect on the cathode performance. The azo bond cleavage of AYR resulted in the formation of p-phenylenediamine, p-nitraniline and 5-aminosalicylic acid. The decolorization efficiency was further enhanced under the optimized condition of pH (5.2), power supplied (0.5V) and initial AYR concentration (100mg/L), reaching up to 99.2 % within 48 hours with the bio-cathode BESs seeding with the enriched inoculum.