The environmental quality regulations for palm oil mill effluent (POME) has reduced the biological oxygen demand (BOD) level to 5000 mg litre-1 as the first generation discharge standard limit. However, the discharge limit was subsequently revised and drastically reduced to the present limit of 100 mg litre-1. It is anticipated that the discharge limit will be further reduced to 50 mg litre-1, and in places where wastes are discharged into rivers, the expected future limit will be at 20 mg litre-1. The oxidation pond (lagoon) method has been conventionally employed for POME treatment for many years due to low construction and operation costs and easy maintenance. However, the anticipated new effluent discharge standard limits cannot be achieved by the oxidation pond process alone; therefore, an additional aerobe/activated sludge process (ASP) is recommended as a polishing treatment.