The activated sludge and microbial substances influences on membrane fouling in submerged membrane bioreactor: unstirred batch cell test

In this study, the mixed liquor suspended solids (MLSS) concentration, the bound EPS amount in the activated sludge, and the trans-membrane pressure's effect on the specific cake resistance was investigated and the mathematical relationship among these factors proposed using the unstirred batch cell test. In this research, it is assumed that the mixed liquor suspended solids (MLSS) concentration, the bound EPS amount in the activated sludge, and the trans-membrane pressure affect the specific resistance of the cake. Therefore, to establish empirically the functional relationship between these variables, three different experiments are performed independently. As results, it is concluded that the specific cake resistance value is not changed significantly even though the MLSS increases from 4000 to 10,000 mg/L as far as the bound EPS concentration and the trans-membrane pressure are maintained to be constant. Additionally, relatively low pressure ranging from 0.5 to 2.0 psi has no significant influence on the specific cake resistance value. However, the amount of bound EPS affects the specific cake resistance showing the sigmoid relationship between them. Consequently, the functional relationship among the bound EPS, trans-membrane pressure, MLSS, and specific cake resistance and is established based on the empirical data.