A Review of Studies on Micellar Enhanced Ultrafiltration for Heavy Metals Removal from Wastewater

Micellar enhanced ultrafiltration (MEUF) process has been used for the removal of copper, chromate, zinc, nickel, cadmium, serinium, arsenate and organics like phenol, o-cresol. This paper reviews various factors such as operating pressure, surfactant concentration, pH of solution, temperature, presence of non-ionic surfactant and salt, membrane type and its pore size and some inhibiting additives, competing metals on heavy metals and surfactants removals in the MEUF process. In this process, heavy metals removal reached over 99% at the initial concentration of up to 1 mM. Metals removal was enhanced by combining the MEUF treatment with electrolysis or with powdered activated carbon (PAC). Cetylperidinium Chloride (CPC) and Sodium dodecyl sulphate (SDS) surfactants removal from the MEUF permeate was also enhanced by the MEUF-ACF (activated carbon fibre) combined treatment. Surfactant has been recovered from the MEUF retentate solution by treating the retentate with HNO3, H2SO4, HCl, NaOH solution but retentate solution needs further treatment. Electrolysis was found better in the separation of metal and surfactant from the MEUF retentate solution. Further study on MEUF process is required for prolonging the experimental period for the heavy metals removal from wastewater. Investigation is also needed to treat highly concentrated solution, and to treat real wastewater.