Anion exchange resin/quartz sand bi-layer composite dynamic membranes in ultrafiltration for algae-laden water treatment

Abstract

Ultrafiltration treatment of algae-laden water is the biggest challenge of membrane fouling. In this study, a bi-layer composite dynamic membrane was constructed by depositing anion exchange resin (AER) and quartz sand on the surface of UF membrane to enhance the separation performance and reduce membrane fouling. AER deposition layers improve contaminants removal and reduce membrane fouling based on retention and ion exchange effect, however, the large porosity results in less than optimal efficiency gains. Deposition of quartz sand on the AER deposit layer significantly enhanced pollutants removal rate and reduced the fouling resistance of the membrane. Compared to AER deposition alone, the bi-layer significantly improved the removal of DOC (20%), UV254 (22%), protein (18%), polysaccharide (13%), MC-LR (11%), GSM (18%) and 2-MIB (3%) and slowed down the development of fouling resistance when the amount of quartz sand deposited reached 68.6 g/m2. As the quartz sand deposition increased to 91.4 g/m2, the presence of a critical value was found, and although the pollutants retention rate increased further, reversible fouling appeared to increase. SEM image analysis of the dense sediment layer traps too much contaminants, resulting in a gel-like layer of contamination that increases membrane fouling.