Ultrafiltration of orange press liquor: effect of operating conditions on membrane fouling and permeate flux

Orange press liquor, a by-product of the orange juice production, was clarified by cross flow ultrafiltration (UF), on laboratory scale, by using polysulphone hollow fibre membranes with molecular weight cut-off of 100 kDa. The effect of operating conditions, such as transmembrane pressure, feed flow rate and temperature, on fouling index, total resistance and permeate flux was investigated. Analysis of the results revealed that in the range of operating values investigated permeate flux increased with temperature, pressure and feed flow rate according to concentration polarization models. Total resistance and fouling index increased with pressure and decreased with feed flow rate. An increase of temperature in the range 15-35 °C reduced the value of total resistance but enhanced the fouling index. According to the experimental results the optimum conditions to maximize permeation fluxes were found to be 1.4 bar of pressure, 35°C and a feed flow rate of 245 L/h; on the other hands, operating conditions of 0.2 bar, 15 °C and 245 L/h were identified as the best ones to minimize membrane fouling.