The palm oil industry generates large volumes of palm oil mill effluent (POME) – 52 million tonnes by 392 palm oil mills in 2005 (0.7 t per tonne fresh fruit bunch processed). Due to the high organic content of POME, anaerobic, followed by aerobic, digestion are employed to reduce its biological oxygen demand (BOD) to 50 mg per litre before discharged into public waterways. Despite the good BOD removal by the processes, the volume of the residual sludge remains considerable. It is estimated that 1800 m3 per year of sludge are produced by a mill processing 500 t per day of fresh fruit bunch (FFB) with another 7200 m3 of undigested suspended solids from the influent stream, resulting in a total of 9000 m3 a year. The sludge in a biological pond would require proper management to prevent its deposition at the bottom which would then slow down the organic matter decomposition compromising the BOD removal efficiency.

Main Research: Mohamad Sulong