Removal of tetracycline hydrochloride from wastewater by nanofiltration enhanced by electro-catalytic oxidation

Abstract

Electro-catalytic oxidation enhanced cross-flow nanofiltration system has been carried out to treat tetracycline hydrochloride wastewater, using Ti/SnO2–Sb anodes prepared by the method of pulse electrodeposited and the membrane of NF90 in the laboratory-scale membrane module. The effects of electro-catalytic oxidation for controlling the fouling of the membrane and concentration polarization were studied in the present paper. Flux change and filtration resistance were studied in order to characterize weakening the concentration polarization and membrane fouling by the introduction of electro-catalytic oxidation. A comparative study between classic nanofiltration and coupling process was then performed at different operating conditions including current density, operating pressure, cross flow velocity and the initial feed concentration. Experimental results showed that electro-catalytic oxidation could reduce the resistance of concentration polarization and cake layer. The filtration rate was found to increase with the increasing in current density and transmembrane pressure. It was no response that did the filtration rate has on the cross flow velocity due to a thin layer of concentration polarization, which was caused by the introduction of electro-catalytic oxidation. Permeate flux decreased with the increasing in initial feed concentration. Morphological difference of the membrane surface between the two processes was studied by a scanning electron microscope.