Palm oil mill effluent (POME) treatment and bioresources recovery using ultrafiltration membrane: Effect of pressure on membrane fouling

Abstract

An attempt was made to examine the effect of applied pressure on membrane fouling that might influence the potential use of ultrafiltration (UF) membrane in treating as well as recovering the bioresources, namely protein and carbohydrate from complex feed like palm oil mill effluent (POME). POME was first subjected to physical pretreatment processes, consisting of depth and surface filtration in order to remove the total suspended solids (TSS). The pretreatment processes enabled the reduction of TSS, turbidity, total dissolved solid (TDS) and chemical oxygen demand (COD) up to 97.3%, 88.2%, 3.1% and 46.9%, respectively. Protein (45.3%) and carbohydrate (41.5%) that retained as insoluble matters together with suspended solids might be used as fertilizer or animal feed by-products. Then, polysulphone UF membrane of 20 kDa was used in the UF membrane study. This study indicated that the applied pressure imposed a direct effect on fouling, permeate flux, protein and carbohydrate recovery as well as wastewater treatment. In total, the permeate flux decreased with filtration time until it reached steady-state values. Beyond a certain applied pressure between 0.6 and 0.8 MPa, the increase in permeate flux with pressure was negligible and insignificance. The highest applied pressure (0.8 MPa) encouraged the formation of fouling up to 85.8% but at the same time enabled the recovery of protein and carbohydrate up to 61.4% and 76.4%, respectively. The highest reduction of TSS, turbidity, TDS and COD also occurred at 0.8 MPa up to 97.7%, 88.5%, 6.5% and 57.0%. The study revealed that it is possible to have appropriate control of applied pressure in order to favor fouling that would, in turn, lead to better rejection of other solutes present in the feed.