Influence of the cleaning temperature on the permeability of ceramic membranes

Membrane separation technologies applied to protein purification is an interesting development that has seen growth in recent years. However, studies about the long-term effects of the cleaning stage, considering different chemical agents and operating conditions, on the performance of the membranes are scarce in the literature. The purpose of this study was to evaluate experimentally the effect of a caustic–surfactant solution (the most commonly used for protein cleaning) at three different cleaning temperatures (30, 50 and 60ºC) upon a 300 kDa tubular ceramic membrane. To this end, 15 repeated fouling and cleaning cycles with a mixture of model proteins, β-lactoglobulin and BSA, were performed. The cleaning temperature of 50ºC was found to be the optimal due to: (a) its capability to restore the permeability to the initial values after each operating cycle, (b) the higher yield regarding protein separation. A process of membrane pore erosion was found for the cleaning temperature of 60ºC.

A different behaviour of the ceramic membrane was observed depending on the cleaning temperature applied. The cleaning temperature of 50ºC showed the best behaviour with regard to recovery of initial conditions and reproducibility. The cleaning temperature of 30ºC seemed to promote an irreversible fouling during the first operating cycles that remained present during the process. The cleaning temperature of 60ºC showed the worst characteristics, including erosion of membrane pores and a generation of fouling that lead to a total retention of the proteins.