THE TREATMENT OF ANAEROBICALLY DIGESTED PALM OIL MILL EFFLUENT BY PRESSURISED ACTIVATED-SLUDGE

The application of the pressurized activated sludge process in the secondary treatment of anaerobically digested liquor of palm oil mill effluent (POME) as influent under various physical conditions was studied. Separation of the particulates was by way of a dissolved air flotation unit. Results showed that a high efficiency in pollutant removals could be achieved and the final treated water was of good effluent quality. The high efficiency of the process was linked to the high rate of oxygen transfer at elevated pressure in the reactor. With a dissolved oxygen level of 10-14 mg dm** minus **3 in the reactor, filamentous growth and sludge bulking were prevented. The kinetic coefficients for the process were also evaluated. It is envisaged the process could complement the anaerobic digestion in a two-stage complete treatment system for POME.