Influence of process temperature and microfiltration pre-treatment on flux and fouling intensity during cross-flow ultrafiltration of sweet whey using ceramic membranes

The use of ultrafiltration in whey processing is limited by reduced flux and separation originating from fouling. Since the processing conditions applied determine ultrafiltration performance, this study focused on investigating the influence of temperature (20 or 50 °C) and the pre-treatment applied (pasteurisation, cross-flow microfiltration) on the ultrafiltration of sweet whey using a 20 kDa ceramic membrane. The highest flux and the lowest total filtration resistance were recorded at 20 °C, with predominantly reversible fouling, most probably arising from protein deposition, while at 50 °C, calcium could have played an important role. Whey microfiltration using a 0.5 μm ceramic membrane enhanced ultrafiltration, giving significant flux increase and fouling reduction, while the obtained microbial reduction was almost equal to pasteurisation. Ultrafiltration of pasteurised whey at 50 °C proved to be least suitable, while ultrafiltration of fresh or microfiltered whey at 20 °C provided the most desirable conditions.