A novel approach for mitigation of membrane fouling: Concomitant use of flocculant and magnetic powder.

Membrane fouling alleviation by addition of poly dimethyl diallyl ammonium chloride (PDMDAAC) and magnetic powder (Fe3O4) was investigated. It was found that magnetic powder associated with PDMDAAC had a good performance on mitigation of membrane fouling, improvement in dehydrogenase activity and enhancement of biomass growth. The optimal dose of PDMDAAC was determined by using constant pressure dead-end filtration unit. Maximum permeate flux was attained at 400mg/L of PDMDAAC addition. Continuous experiment was conducted in a submerged membrane bioreactor (MBR) system and biomass parameters such as soluble microbial products (SMP), extracellular polymeric substances (EPS), dehydrogenase activity, zeta potential, and capillary suction time (CST) were analyzed. Best results were obtained with a combination of 120mg/L of magnetic powder and 400mg/L of PDMDAAC. This study results demonstrated that PDMDAAC played a major role in SMPc and EPSc reduction, whereas magnetic powder had better performance in decreasing SMPc and EPSp.