Activated carbon (AC) was added into the activated sludge to alleviate membrane fouling during sludge microfiltration. The fouling mitigation profiles were evaluated at different AC sizes and doses by a single-fibre microfiltration system. It was found that the granular AC added in the sludge suspension can absorb the organic substances in the sludge in a certain level, including biopolymer clusters (BPC). There are three impacts from AC addition, including the positive effect by mechanically scouring the membrane surface, the positive effect by adsorb organic substances, and the negative impact of breaking up sludge flocs to release the organic matter. The whole effect of AC addition on membrane fouling has to depend on the relative intensity of these three effects. The suitable AC should have a smaller mean size below 200 μm, by which the membrane fouling mitigation efficiency was positively correlated with AC doses.
Keywords: activated carbon adsorption, activated sludge, biopolymer clusters, BPC, membrane fouling, environmental technology and management