Membrane fouling in a powdered activated carbon – membrane bioreactor (PAC-MBR) for micro-polluted water purification: Fouling characteristics and the roles of PAC

Abstract

To identify the characteristics of fouling in the powdered activated carbon – membrane bioreactor (PAC-MBR) for micro-polluted water treatment, a pilot-scale PAC-MBR was continuously operated for 4 months without chemical cleaning. The membrane autopsy suggested that physically recoverable and irrecoverable fouling accounted for 56.6 and 43.4% of the total fouling, respectively, and intermediate blocking model showed the best fitting for fouling evolution. Colloidal matter, which had a large proportion of protein and polysaccharide, was the major contributor to the physically recoverable fouling resistance, while polysaccharide and humic substances were the major contributors to the physically irrecoverable fouling resistance. By comparing the MBRs with and without PAC, it was found that PAC increased fouling rate because it exerted a marginal effect on foulants reduction and membrane scouring, but a synergistic effect on cake layer formation. These fouling characteristics in PAC-MBR were different from those in the MBRs for municipal wastewater treatment, which could be ascribed to the poor-nutrient of the micro-polluted water.