Application of feedback control based on dissolved oxygen to a fixed-film sequencing batch reactor for treatment of brewery wastewater

Treatment of brewery wastewater was performed using an aerobic fixed-film sequencing batch reactor using a feedback control system based on dissolved oxygen concentration in the mixed liquor. This control system was modeled after the self-cycling fermentation technique. The system was operated at 25 and 35 degrees C and under growth-rate limiting conditions. Total biochemical oxygen demand (TBOD) removal efficiency was 83% after 3 hours at 25 degrees C and 92% after 1.5 to 2 hours at 35 degrees C. The treated effluent produced had a TBOD between 120 and 438 mg/L, with suspended solids contributing between 63 and 71% of the TBOD. Effectiveness of the treatment process might be improved if an efficient secondary clarifier was installed or if the suspended solids were removed from the brewery wastewater before treatment.