Treatment of wastewater from the meat manufacturing industry‐case study

Abstract

Meat manufacturing mill wastewaters (MMM) originating from meat processing units are the most polluted wastewaters of the food industry. Discharged wastewater was characterized by high values of COD, BOD and TSS (6612, 2550 and 6220) mg/l, respectively. Moreover, the wastewater contains significant concentrations of oil and grease amounting to 4482 mg/l. Treatment processes namely, plain sedimentation, plain flotation, pressurized dissolved air flotation, chemical coagulation and biological treatment via a completely mixed activated sludge process, were chosen for this study. The results obtained revealed that plain sedimentation, column flotation and dissolved air flotation (DAF) exhibited good efficiency in removing flotation fats (93.5, 96, and 97.3%, respectively). Alum, ferrous sulfate and ferric chloride precipitation in‐combination with lime at their optimum operating conditions as minimal pre‐treatment procedures for the removal of organic matter contents exhibited good efficiency of COD, BOD, and oil and grease. The chemically treated effluent doesn't comply with the Law No.4/1994 (Egyptian Standards which regulating the discharge of industrial wastewater to the sewerage network). This is due to the high concentration of soluble organics. Activated sludge plant (ASP) with long aeration time (8hr) was suitable for the case under consideration. Results show that average residual COD, BOD, TSS and oil and grease were 270, 62, 78 and 9.8 mg/l, respectively. The biologically treated effluent is complying with Standards of discharge wastewaters to the sewerage network.