Adsorption of residual oil from palm oil mill effluent using rubber powder

Abstract

A synthetic rubber powder was used to adsorb the residual oil in palm oil mill effluent (POME). POME is the wastewater produced by the palm oil industry. It is a colloidal suspension which is 95-96% water, 0.6-0.7% oil and 4-5% total solids including 2-4% suspended solids originating in the mixing of sterilizer condensate, separator sludge and hydrocyclone wastewater. POME contains 4,000 mg dm-3 of oil and grease, which is relatively high compared to the limit of only 50 mg dm-3 set by the Malaysian Department of Environment. A bench-scale study of the adsorption of residual oil in POME using synthetic rubber powder was conducted using a jar test apparatus. The adsorption process was studied by varying parameters affecting the process. The parameters were adsorbent dosage, mixing speed, mixing time and pH. The optimum values of the parameters were obtained. It was found that almost 88% removal of residual oil was obtained with an adsorbent dosage of 30 mg dm-3 and mixing speed of 150 rpm for 3 hr at a pH 7. Adsorption equilibrium was also studied, and it was found that the adsorption process on the synthetic rubber powder fit the Freundlich isotherm model.