Management of wastewater from soap and food industries: a case study

This paper presents the wastewater management of an industrial complex which produces different products, i.e. soap, perfume extract, macaroni, jam and juices. A continuous monitoring programme for departmental as well as final effluents was carried out for almost 3 months. Characterization of the composite wastewater from both soap and food processing plants indicated that the waste was highly contaminated with organic compounds as indicated by COD and BOD values. Moreover, effluent from the soap manufacturing plant contains significant concentrations of oil and grease amounting to 563 mg l-1. Soap manufacturing effluent and the combined wastes discharged from the whole industrial complex were subjected to different treatment processes, namely dissolved air flotation, chemical coagulation-sedimentation, and biological treatment via a completely mixed activated sludge process. Although coagulation using alum followed by sedimentation removed 52% of COD, residual values did not comply with the regulatory standards. Biological treatment of the composite combined wastewater significantly removed the organic contaminants in wastewater. Average residual BOD, COD, oil and grease values were 30, 92 and 8.3 mg l-1 respectively. Based on the laboratory results a final process design was developed.