December 2010, Volume 1, No.2 International Journal of Chemical and Environmental Engineering Tertiary Treatment of Biologically Treated Palm Oil Mill Effluent (POME) Using UF Membrane System: Effect of MWCO and Transmembrane Pressure Munirat Abolore Idris a , Mohammed Saedi Jami, Suleyman Aremu Muyibi Bioenvironmental Engineering Research Unit (BERU) Department of Biotechnology Engineering Faculty of Engineering, International Islamic University, Malaysia. a Corresponding author: munirataboloreidris@yahoo.com Abstract This study evaluate the performance of ultrafiltration UF membrane system in the treatment of biologically treated palm oil mill effluent (POME) by varying the effects of transmembrane pressure and using different molecular weight cut-off (MWCO). Flat sheet polyethersulfone (PES) ultrafiltration membrane of molecular weight cut-off (MWCO) 1 kDa and 5 kDa were used in this study. Biologically treated POME was subjected to physical pretreatment processes, consisting of coagulation and adsorption to remove total suspended solids. Transmembrane pressure was varied between 0.5 bar to 1.5 bar and the performance of these membrane systems were assessed in terms of reduction of chemical oxygen demand (COD), color and turbidity in POME. Pretreatment processes which consist of coagulation and adsorption showed remarkable results in reducing COD, color and turbidity up to 92.8 %, 99.3 % and 99.9 % respectively. At transmembrane pressure 0.5 bar, more reduction in COD, colour and turbidity were observed. The smallest MWCO of the membrane at transmembrane pressure 0.5 bar gave a better reduction of pollutants from the pretreated POME. The increasing transmembrane pressure leads to a corresponding increase in permeate flux which starts to level off at higher transmembrane pressures. The application of membrane separation technology to treat biologically treated POME has improved the quality of the final effluent discharged. The UF membrane plays very important role in reducing pollutants present in biologically treated POME. Keywords: POME, polyethersulphone, COD, MWCO, turbidity 1. Introduction The production of palm oil generates wastes that are of great concern to the environment. The process of palm oil mill production consumes large amount of water and 50 % of it ends up as palm oil mill effluent (POME). POME is a highly colloidal suspension of 95- 96 % water, 0.6-0.7 % oil and 4-5 % total solids including 2-4 % suspended solids originating from the mixture of a sterilizer condensate, separator sludge and hydrocyclone wastewater [1]. POME is a highly voluminous liquid waste which has an unpleasant smell and very polluting. Therefore, it is an urgent need to find a compromising way that will enable the balance between the environmental protection and sustainable reuse of the water in the POME. Majority of palm oil mill uses conventional biological treatment of aerobic, anaerobic or facultative ponds which needs large area and long treatment periods [2]. This conventional treatment system is quite inefficient and this unfortunately leads to the environmental pollution issues [3]. Thus, the discharge of inefficiently treated POME creates adverse impact to the environment.Membrane technology has become a recognized separation method that is well suited for the recycling and reuse of wastewater. The main advantages of membrane technology is constant production of high quality water, non toxic and fully automated process [3]. Recently, ultrafiltration UF has been successfully used as a separation method in various industrial process especially in the production of pure water, food and pharmaceutical industries. However, major drawbacks of using membrane includes fouling, and decline in permeate flux. This flux decline leads to an increase in the membrane cleaning and replacement costs [1]. A number of studies have been carried out to overcome the problem of decline in flux and fouling. The introduction of pretreatment units for modifications of feed water by removing suspended solids that may