Investigation on Roles of Membrane Fouling in Chromium Removal From Aqueous Effluent of Chemical Industry: Application to Nanofiltration Membranes

In this paper, the integral method was used to investigate the fouling phenomenon pertaining to nanofiltration membrane (NF) of chromium removal from wastewater. This method is adopted since the error arising from the differential method could be eliminated by data integration with time. The benefit of this method is to fit the flux decline according to the fouling mode occurring in single or multistage phases. In addition, the effect of operating parameters, like feed flow and applied pressure, on fouling behavior can be easily determined. For applied pressure less than 10 bar and in laminar flow, flux decline was approximated by a single model of the cake layer. However, for turbulent flow, dual fouling modes of complete pore blocking and cake models were found to fit flux decline properly. Furthermore, at a pressure higher than 10 bar and for both laminar and turbulent flow, flux decline was fitted very well by two successive fouling models, namely partial and complete blocking. Finally, optimized operating conditions are recommended to avoid such fouling behavior and increase water productivity. In particular, for laminar flow, it is recommended to operate at the upper limit of feed flow, while for turbulent flow, operating at the lower limit of flow is favored.