Simultaneous removal of heavy metals from phosphorous rich real wastewaters by micellar-enhanced ultrafiltration

Abstract

In this study micellar-enhanced ultrafiltration (MEUF) was used to simultaneously remove heavy metals from phosphorous rich drainage waters of a fertilizer company, obtaining the purification of the nutrient rich wastewater. Response surface methodology approach was used to model and optimise the rejection coefficients of cadmium and copper. The factors studied were pH and SDS feed concentration. Results show that the removal of copper and cadmium was more efficient at low pH values. SDS feed concentration higher than 60mM was needed to obtain an efficient removal of cadmium and copper due to the competition of other metals present in the real drainage waters. The optimum rejection coefficients achieved were 84.3% and 75.0% for cadmium and copper, respectively, at the pH value of 3.2 and SDS feed concentration of 75.6mM. In addition, calculated rejection coefficients for zinc and nickel show that copper was the least trapped heavy metal and the MEUF removal efficiency was as follows, Zn=Ni>Cd>Cu. The flux decreased when increasing SDS feed concentration due to concentration polarisation, which was more significant above the SDS feed concentration of 60mM. Irreversible fouling was negligible in the whole set of experiments. Secondary pollution due to the SDS leakage to the permeate was also negligible.