Effect of ionic strength on rinsing and alkaline cleaning of ultrafiltration inorganic membranes fouled with whey proteins

The rinsing and alkaline cleaning of an ultrafiltration (UF) inorganic membrane fouled with whey proteins was investigated. The progression of both processes was assessed by membrane hydraulic resistance restoration and fouling deposit removal. The amount of protein removed during rinsing is quite significant, as compared to the total amount removed during rinsing and cleaning. Increased ionic strength of the rinsing solution, by means of NaCl addition, resulted in an impressive increase of calcium removal during the rinsing step. This can be probably attributed to calcium/sodium ion exchange. The effect of increased calcium removal on rinsing and cleaning efficiency was not significant. The kinetics of rinsing and cleaning were also considered.