Study on Fouling of Nanofiltration Membranes when Treating Reclaimed Water

摘要

According to effluent water quality character- ristics of membrane bioreactor (MBR) in the municipal sewage treatment plant, major foulants which causing fouling of nanofiltration membrane elements in subsequent nanofiltration system were analyzed. And based on finding out the major foulants, a suitable cleaning method was determined in this paper. In this paper, determining the fouling level of nanofiltration membrane fouled with the effluent of membrane bioreactor (MBR) based on the change of pressure about nanofiltration system. In order to investigate the fouling reasons and cleaning methods of nanofiltration membrane, SEM and EDX were applied to analyze the membrane fouling layer. The experimental results showed that, the pressure of nanofiltration system was increased 30% after 90 days running. And the result of SEM- EDX about membrane showed that, the major foulants of membrane include organic substances and silicon dioxide. And there may be some inorganic substances, which contained magnesium (Mg) and calcium (Ca). Thought cleaning experiments with HC1, NaOH, STPP (Sodium tripolyphosphate, Na5P3O10) +Na-DDBS (sodium dodecyl benzene sulfonate, C6H5(CH2)12-S03Na)about fouled membrane, it was further showed that the foulants of membrane include organic substances, silicon dioxide and some inorganic substances which contained magnesium(Mg) and calcium(Ca).