Efficient azo dye decolorization in a continuous stirred tank reactor (CSTR) with built-in bioelectrochemical system

A continuous stirred tank reactor with built-in bioelectrochemical system (CSTR-BES) was developed for azo dye Alizarin Yellow R (AYR) containing wastewater treatment. The decolorization efficiency (DE) of the CSTR-BES was 97.04   ±   0.06% for 7   h with sludge concentration of 3000   mg/L and initial AYR concentration of 100   mg/L, which was superior to that of the sole CSTR mode (open circuit: 54.87   ±   4.34%) and the sole BES mode (without sludge addition: 91.37   ±   0.44%). The effects of sludge concentration and sodium acetate (NaAc) concentration on azo dye decolorization were investigated. The highest DE of CSTR-BES for 4   h was 87.66   ±   2.93% with sludge concentration of 12,000   mg/L, NaAc concentration of 2000   mg/L and initial AYR concentration of 100   mg/L. The results in this study indicated that CSTR-BES could be a practical strategy for upgrading conventional anaerobic facilities against refractory wastewater treatment.