P2269@com.qz.se ("ENG-LEONG FOO ", MIRCEN-STOCKHOLM) (05/11/89)
Chan Wing Palm Oil Mill is located in the State of Johor in peninsular Malaysia. The mill is capable of processing 60 tonnes of fresh oil palm fruits per hour into 12 tonnes of crude palm oil and 4 tonnes of palm kernel. At the same time it will also produce 36 tonnes of effluent. The mill currently processes between 200,000 and 250,000 tonnes of fresh fruits per year. Palm oil effluent has a high BOD of about 30,000 mg/l with a pH of around 4 and a temperature of 70 to 80 degrees celcius. It has no toxic substances that may inhibit growth of microorganisms and has a high buffering capacity which allows its anaerobic digestion without the need for neutralization. Effluent treatment involves anaerobic digestion and the land application of the digested effluent. Without pretreatment, the effluent is pumped from a storage pit into two anaerobic digesters. Each digester is 23 m in diameter and 10.7 m high with an operating capacity of 4200 m3. The digester is constructed from mild steel with epoxy coating of the internal surfaces. Stirring is by biogas recirculation through a biogas compressor driven by a 7.5 kW motor. The digesters are also equipped with flame arresters, pressure relief and vacuum breaker valves. The maximum operating pressure of the digester is 24.4 cm water. Biogas produced run a 250 kW gas generating set and estimated to generate a savings of USD 114,320 worth of diesel fuel per year. This only represents 55 % of the currently used biogas. The remaining 45 % is flared but plans for the total use of the biogas is being undertaken. Source: Palm oil mill effluent treatment and by-product utilization. Lecture notes by Quah Swee Khoon (Malaysia).