Biological Treatment of Soya Bean Waste

Soya bean beverages and “Tofu” are the major sources of protein in the Asian diet. Wastewater from soya bean food processing plant consisted of high concentration of BOD₅, COD, nitrogen and phosphorus. The wastewater should be pre-treated before discharging into the sewer or watercourses. Activated sludge process was an effective biological treatment process for soya bean wastewater. Up to 95% of BOD₅ can be removed by activated sludge orocess. The removal of nitrogen and phosphorus were 67% and 57% respectively. The treatment efficiency increased with higher mean cell residence time. The settleability of activated sludge was good, and suspended solids removal efficiency was well above 90%. The biological kinetic coefficients were also determined from the pilot study.