Study of permeate flux in micellar-enhanced ultrafiltration on a semi-pilot scale: Simultaneous removal of heavy metals from phosphorous rich real wastewaters

摘要

The study reports on the successful application of micellar-enhanced ultrafiltration (MEUF) for the purification of phosphorous rich real wastewaters of a fertilizer company. Flux decline was investigated in a cross-flow, semi-pilot scale equipment using a 10kDa spiral-wound polyethersulfone membrane. Full factorial design complemented to a central composite design was applied to evaluate the effect of factors (cross-flow velocity, transmembrane pressure and feed concentration of SDS) on permeate flux. Transmembrane pressure and cross-flow velocity showed a positive statistically significant effect on the permeate flux. When increasing the cross-flow velocity above 0.24 m/s a plateau in permeate flux was observed. A significant interaction effect between the cross-flow velocity and pressure was observed. The effect of the pressure was affected by the level of the cross-flow velocity, and vice versa. The concentration polarisation phenomenon was significant leading to a relative flux of 0.5. However, after 2 h of experiments, irreversible fouling was negligible. Concentration of SDS did not have statistically significant effect on the permeate flux but it affected positively the rejections coefficients of cadmium and copper. Rejection coefficient up to 85% and 81% were obtained for cadmium and copper, respectively, whereas phosphorous was not retained by the membrane.