Anaerobic-Aerobic combined system for the biological treatment of azo dye solution using residual yeast.

Abstract

This study aimed to investigate the treatment efficiency of a synthetic dye solution in an anaerobic‐aerobic combined reactor system, using pretreated residual yeast as a nutrient source and redox mediator. The applicability of the residual yeast as a nutrient source was firstly evaluated in anaerobic batch tests. Subsequently, two continuous bench‐scale treatment settings were studied: (1) an Upflow Anaerobic Sludge Blanket (UASB) reactor followed by an activated sludge system and, (2) a UASB reactor followed by a shallow polishing pond. The two system configurations were fed with a synthetic azo dye solution of Yellow Gold Remazol (50 mg/L) and pretreated residual yeast (350 mg/L). According to the results, the UASB/shallow polishing pond‐combined reactor attained the best values of chemical oxygen demand (COD) (85%) and dye removal (23%).