Membrane Water Treatment, Vol. 6, No. 4 (2015) 293-308 DOI: http://dx.doi.org/10.12989/mwt.2015.6.4.293 293 Copyright © 2015 Techno-Press, Ltd. http://www.techno-press.org/?journal=mwt&subpage=7 ISSN: 2005-8624 (Print), 2092-7037 (Online) Optimization of POME treatment process using microalgae and ultrafiltration R.I. Ibrahim 1 , A.W. Mohammad 2 and Z.H. Wong 2 1 Department of Electromechanical Engineering, University of Technology, Iraq 2 Department of Chemical and Process Engineering, The National University of Malaysia, Malaysia (Received October 13, 2014, Revised March 16, 2015, Accepted April 03, 2015) Abstract. Palm oil mill effluent (POME) was produced in huge amounts in Malaysia, and if it discharged into the environment, it causes a serious problem regarding its high content of nutrients and high levels of COD and BOD concentrations. This study was devoted on POME treatment and purification using an integrated process consisting of microalgae treatment followed by membrane filtration. The main objective was to find the optimum conditions as retention time and pH in the biological treatment of POME. Since after the optimum conditions there is a diverse effect of time and the process become costly. According to our knowledge, there is no existing study optimized the retention time and percentage removal of nutrients for microalgae treatment of POME wastewater. In order to achieve with optimization, a second order polynomial model regression coefficients and goodness of fit results in removal percentages of ammonia nitrogen (NH 3 -N), orthophosphorous (PO 4 −3 ), COD, TSS, and turbidity were estimated. WinQSB technique was used to optimize the objective function of the developed model, and the optimum conditions were found. Also, ultrafiltration membrane is useful for purification of POME samples as verified by experiments. Keywords: POME; microalgae; optimization; membrane filtration 1. Introduction Raw palm oil mill effluent (POME) wastewater is a colloidal suspension containing 95-96% water, 0.6-0.7% oil, and 4-5% total solids, including 2-4% suspended solids that mainly consist of debris from the palm fruit mesocarp generated from three main sources, namely sterilizer condensate, separator sludge, and hydrocyclon wastewater. Also POME contains high concentrations of proteins, carbohydrate, nitrogenous compounds, lipids and minerals that may be converted into useful materials using microbial processes (Wu et al. 2007). If this untreated POME was thrown out to the environment, it has a negative effect on it. Therefore it must be a critical needful solution savings the equilibrium between environmental safety and sustainable energy that can be produced from nutrient materials existing in the POME (Ahmad et al. 2005). Bio-treatment of POME with microalgae is the solution because the algae grows in photosynthesis method that has the ability to use solar energy and transforming it to a profitable biomass take advantages from nitrogen and phosphorous compounds presented already in POME. Microalgae culture becomes an economizing solution to the problem treats the wastewater by Corresponding author, Associate Professor, Dr. Raheek I. Ibrahim, E-mail: doctorraheek@yahoo.com