In this work, the effect of operating parameters on the ultrafiltration of "labaneh" whey in hollow-fiber membranes was investigated. Polysulfonic, hollow-fiber membranes, with nominal molecular weight cut-off (NMWCO) of 5, 30, and 100 kDalton, were used in the ultrafiltration process. Different operating conditions of temperature, pH, protein and total solid concentration, transmembrane pressure, flow rates, and pre-treatment were studied. It was found that flux increased with increasing trans-membrane pressure, temperature, and flow rate. This was attributed to the drop in the resistance on the membrane surface. Flux was found to decrease when the pH was increased. Higher pH was found to be responsible for tricalcium phosphate colloid formation, which led to a higher fouling rate in the membrane. Larger pore size was found to enhance the flux by decreasing the membrane intrinsic resistance. The efficiency of the ultrafiltration (UF) process in concentrating protein in labaneh whey was also studied. The UF process was found efficient in concentrating protein in labaneh whey when a 30 kDa membrane was used. It was found, however, that the 100 kDa membrane was inefficient for concentrating protein in labaneh whey. In this case, protein was found to pass through the membrane"s surface.

 Arabian J. for Sci. & Eng. 26(2C), 55–67 (2001)