Treatability Studies of Palm Oil Refinery Wastewaters

Abstract

Wastewaters from palm oil refineries were treated using physical-chemical and biological treatment systems. Dissolved air flotation (DAF) af ter chemical coagulation and flocculation with lime, alum, and polyelectrolyte removed more than 90% of the influent COD, suspended solids, and oil and grease. Laboratory data compared closely with pilot and full scale plant operating data. Pretreated wastewaters from physical and chemical refining were further treated with the sequencing batch reactors (SBRs). The SBRs allow the control of reaction time and the maintenance of biological solids to be accomplished in a single tank. Laboratory and pilot scale studies showed a high degree of BOD and COD removal efficiencies. Microprocessor-based timers were used to control the operating modes. The cycle times used varied from 8 to 24 hours. The process showed stability under wide variations of organic strength (300 to 2500 mg/l BOD) and loading rates (0. 4 to 2. 0 mg COD/mg MLVSS).