The performance of electrode ultrafiltration membrane bioreactor in treating cosmetics wastewater and its anti-fouling properties

Abstract

The membrane fouling problem of the membrane bioreactor (MBR) for wastewater treatment reduces the membrane flux and the pollutants removal efficiencies, which is the major obstacle limiting its application and should be properly solved. The combination of membrane and electricity can effectively slow down the membrane fouling rate due to electric repulsion between the pollutants and the membrane. In this study, the performance and the membrane fouling features of an electrode ultrafiltration membrane bioreactor (EMBR) fed with cosmetics wastewater were compared with a conventional ultrafiltration membrane bioreactor (UMBR). The results showed the COD removal efficiency increased by 4.43% and the transmembrane pressure (TMP) reduced by 50% in the EMBR as compared with the UMBR. The specific surface areas of electrode ultrafiltration membrane and conventional ultrafiltration membrane declined by 56.9% and 78.8% after 90 days of operation, respectively. The Protein (PN), polysaccharide (PS) and humic acids (HA) in the cake layer of EMBR were only 61.27%, 78.37% and 34.85% of that of UMBR, which contributed to its loose and porous structure and thus decreased the growth rate of TMP and extended the operation cycle. Extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory calculation proved that the energy barrier between the electrode ultrafiltration membrane and the pollutants was 50% higher than that between the conventional ultrafiltration membrane and the pollutants. Therefore, the strong anti-fouling property of the electrode ultrafiltration membrane could reduce the chemicals dosage and manpower consumption for membrane cleaning and could be preferred for the treatment of cosmetics or alike wastewater containing high concentrations of surfactants and fatty acids.