Cleaning of ultrafiltration membranes fouled with BSA by means of saline solutions

Abstract

In this work, four ultrafiltration (UF) membranes with molecular weight cut-offs (MWCOs) of 5, 15, 30 and 50 kDa, respectively, were fouled with 1% BSA aqueous solutions and cleaned with different saline solutions. The influence of MWCO, membrane material and operating conditions on the cleaning effi- ciency was investigated. Saline solutions were able to clean the 5, 15 and 30 kDa membranes, but not the 50 kDa membrane. NaCl, NaNO3, NH4Cl and KCl were the most effective salts. The cleaning tests demonstrated that the higher the temperature of the saline solution was, the higher the cleaning efficiency was also. In addition, an increase in the crossflow velocity resulted in an increase in the hydraulic cleaning efficiency (HCE). However, there was an optimum value of salt concentration to clean the membrane effectively. Response Surface Methodology was used to investigate the relationship between salt concentration and temperature in the cleaning process.