273 ZERO DISCHARGE TREATMENT TECHNOLOGY OF PALM OIL MILL EFFLUENT SOH KHEANG LOH*; MEI EE LAI*; MUZZAMMIL NGATIMAN*; WENG SOON LIM*; YUEN MAY CHOO*; ZHENJIA ZHANG** and JUMAT SALIMON ‡ Journal of Oil Palm Research Vol. 25 (3) December 2013 p. 273-281 RESEARCH ARTICLES ABSTRACT Palm oil processing operation is invariably accompanied by palm oil mill effluent (POME) considered to be an environmental pollutant. While anaerobic digestion and the present tertiary treatment technologies of POME are able to meet the current regulatory effluent discharge requirement of biological oxygen demand (BOD) 100 mg litre -1 – the current limit set by the Department of Environment (DOE) – the existing technologies are unable to consistently meet the proposed stringent BOD regulatory requirement of 20 mg litre -1 to be imposed by the DOE. This article investigates the possibility of integrating several bioprocesses for POME treatment at the Malaysian palm oil mills by transforming the POME into several high value- added products; with BOD 20 mg litre -1 attainable at its final discharge. This integrated approach has the potential of achieving zero-effluent discharge along with the production of biogas, biofertiliser and recycled water, in treating industrial wastewater to reduce pollution. Keywords: wastewater, biological treatment, biological oxygen demand, biogas, biofertiliser. Date received: 8 January 2013; Sent for revision: 25 April 2013; Received in final form: 4 July 2013; Accepted: 8 July 2013. * Malaysian Palm Oil Board, 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia. E-mail: lohsk@mpob.gov.my ** Shanghai Jiaotong University, 800, Dongchuan Road, Min Hang, Shanghai 200240, the People’s Republic of China. ‡ Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia. INTRODUCTION The Malaysian palm oil industry has been deve- loping over the years and is still progressing, thus assuring the nation of abundant returns. Being the second largest palm oil producer after Indonesia, the palm oil industry contributes greatly to the country’s foreign exchange earnings and the increased living life-style of the Malaysians (Wu et al., 2009). Generally, oil palm (Elaeis guineensis) is one of the most versatile crops in the tropical region, notably in Malaysia and Indonesia. The extraction of palm oil from the fruit of E. guineensis involves a number of processing stages viz. sterilisation, stripping, digestion, pressing, clarification, purification and vacuum drying. In the extraction process, a large quantity of water is required. It is estimated that about 1.5 m 3 of water is needed to process 1 t of fresh fruit bunch (FFB) - half of this water amount ends up as palm oil mill effluent (POME). POME, a highly polluting wastewater generated from the palm oil milling process is thick, brownish with a distinct offensive odour, and has a high organic matter content, but is non-toxic as no chemicals are added during oil extraction (Ahmad et al., 2009). The thick brownish raw POME in the viscous colloidal form is discharged at a temperature between 80°C and 90°C. If the untreated POME is discharged into watercourses, it certainly will cause considerable environmental problems due to its high biological oxygen demand (BOD) (~25 000 mg litre -1 ), chemical oxygen demand (COD) (~50 000 mg litre -1 ), oil and grease (O&G) (4000-8000 mg litre -1 ), total solids (40 500-63 000 mg litre -1 ) and suspended solids (SS) (18 000-30 000 mg litre -1 ) (Ma,1996; Loh et al., 2009).