Filtration performance of three dimensional fabric filter in a membrane bioreactor for wastewater treatment

This study investigates the filtration performance of three dimensional (3D) woven fabric filters with various structures in a membrane bioreactor (MBR). Five 3D woven fabrics with the same component materials but different tightness, and a 2D fabric as the control are adopted as filters in a laboratory-scale submerged MBR. In a 6 h operation, the changes of the fluxes and the turbidities of all filters have the same trend and the 3D filter with the highest porosity has the highest flux and similar turbidity as that of the 2D filter while 3D filter with the lowest porosity has the lowest flux. In a one-month operation, the high porosity 3D filter has total amount of treated water about 1.7 times and 2.5 times as much as those through the low porosity 3D fabric and the 2D filter, respectively. Toward the end of the one-month operation, the ranges of the turbidity for the high porosity 3D filter were 1-1.5 NTU and 1.3-2.5 NTU, 1.6-2.2 NTU for low porosity 3D filter and 2D filter, respectively. The fouling analysis shows that high porosity 3D filter has a thick and the low porosity 3D filter has a thin cake layer mainly circumferentially distributed along sealing rubber ring, while the 2D nylon filter surface only covered by a thin and incomplete cake layer. The 3D filter with lower tightness shows in-depth penetration of foulants while the 2D and 3D tightly woven filters have foulants concentrated in the first layer of the fabrics.