Comparison of fouling behaviors between activated sludge suspension in MBR and EPS model solutions: A new combined model

How to precisely describe the fouling behavior of activated sludge suspension in constant flux cross-flow filtration is a challenge. In this paper, a three-mechanism (standard pore blocking, complete pore blocking and cake filtration) model was established based on the classic blocking law to describe the fouling behavior of activated sludge suspension in the constant flux cross-flow filtration. The results showed that the predictions of the proposed model showed good agreements with experimental data not only for activated sludge suspension (R-2 >= 0.994), but also for bovine serum albumin protein (BSA) (R-2 >= 0.966), humic acid (HA) (R-2 >= 0.940), sodium alginate (SA) (R-2 >= 0.801) and kaolin (R-2 >= 0.961). Meanwhile, for activated sludge suspension, the variation rate of the cake resistance increased with the filtration flux, and the steady available membrane area ratio (A(steady)/A(0)) was independent on the filtration flux while it decreased with the increase of MLSS concentration. In addition, the available membrane area ratio (A(t)/A(0)) decreased slower for activated sludge suspension than that for single model solution (BSA, HA and SA) in the fouling process.

Automated summary

A three-mechanism model was established in this study to describe the fouling behavior of activated sludge suspension in constant flux cross-flow filtration, showing good agreement with experimental data for various substances. The model predicted the fouling behavior accurately for different substances and showed that the variations in cake resistance and membrane area ratio were dependent on filtration flux and MLSS concentration.