Enhanced degradation of azo dye alizarin yellow R in a combined process of iron-carbon microelectrolysis and aerobic bio-contact oxidation

Purpose With the aim of enhanced degradation of azo dye alizarin yellow R (AY) and further removal of the low-strength recalcitrant matter (LsRM) of the secondary effluent as much as possible, our research focused on the combination of aerobic bio-contact oxidation (ABO) with iron/carbon microelectrolysis (ICME) process. Materials and methods The combined ABO (with effective volume of 2.4 1) and ICME (with effectively volume of 0.4 1) process were studied with relatively short hydraulic retention time (HRT) of 4 or 6 h. Results At the HRT of 6 h with the reflux ratio of 1 and 2, the AY degradation efficiency in the final effluent was > 96.5%, and the total organic carbon (TOC) removal efficiency were 69.86% and 79.44%, respectively. At the HRT of 4 h and the reflux ratio of 2, TOC removal efficiency and AY degradation efficiency were 73.94% and 94.89%, respectively. The ICME process obviously enhanced the total AY removal and the generated micromolecule acids and aldehydes then that wastewater backflow to the ABO where they were further biodegraded. Conclusion The present research might provide the potential options for the advanced treatment azo dyes wastewater with short HRT and acceptable running costs.