Reduction in environmental pollution caused by waste waters from edible oil refineries, concept and investigations

The characteristics of waste waters from the manufacture of edible oils are outlined. In West Germany, legislation would require biological treatment of the highly polluting waste streams, and a possible treatment scheme is described, with a flow diagram. It would involved neutralization and cooling of the waste water to 20-30C, controlled addition of supplementary nitrogen, 2-stage biological treatment by a discontinuous activated sludge process followed by a submerged fixed-bed reactor, flotation, and filtration. In pilot-scale studies on the process, the COD was reduced from about 3000 mg per litre to 200 mg per litre and there was almost complete removal of fats and BOD. Design parameters for a full-scale plant are presented.