One of the major unresolved issues faced by the palm oil mills is their inability to address concerns of the global community in finding a permanent solution to handle the large volumes palm oil mill effluent (POME) that the mills generate during the oil extraction process. Unlike most other oil processing industries, the biological oxygen demand (BOD) of the POME usually ranges from 25 000 to 28 000 mg litre^-1. The relatively high volume of the POME which can vary from 65% of the fresh fruit bunch (FFB) processed in a well operated palm oil mill to even 100% of the FFB processed in some mills where its control is not given the priority it deserves. The conventional method of POME treatment practiced by most mills is based on natural degradation of the protein-rich wastewater using both anaerobic as well as aerobic bacteria in a number of large ponds. The bacteria are very active in the anaerobic digestion ponds as it generally brings down the BOD to about 5000 mg litre^-1.