Effects of operational parameters on cake formation of CaSO4 in nanofiltration

Inorganic fouling is one of the major limitations of nanofiltration (NF) application in drinking water treatment. In this study, we report the effect of operating parameters on the fouling of NF membranes by CaSO4 in terms of cake growth at membrane surface under various operating conditions. Increasing operating pressure and decreasing crossflow velocity promote CaSO4 nucleation and crystallization, thus enhance membrane fouling. The flux decline and its dynamics due to the change of operating parameters are assessed quantitatively based on a resistance model. Applied filtration pressure is found to have the most dominant impact on the inorganic fouling. It is shown that the filtration resistance caused by the formation and growth of CaSO4 cake on membrane surface is dependent on operating parameters.