Ribbed PVC-silica mixed matrix membranes for membrane bioreactors

The feasibility of ribbed-PVC-silica mixed matrix membranes (MMM) in a membrane bioreactor (MBR) application was investigated. Three operational aspects were evaluated: inclusion of vibration, use of relaxation (cycle time), and optimization of the cleaning procedure. Results show that the specific ribs on the membranes give a 52% higher surface area compared to the corresponding flat membranes, offering two main benefits: i.e. a higher clean water permeability (increased by 70%) and an increased critical flux (increased by 30%) for activated sludge filtration. Applying vibration increased the critical fluxes about 30-50%. In aeration mode, a filtration time of 8 min and a relaxation time of 1 min are found to keep both reversible and residual fouling minimal. Despite these advantages, the increase of the critical flux and the filtration performance (i.e. fouling resistance) are not completely in proportion with the increase of the surface area. Furthermore, a lower cleaning efficiency for the ribbed membrane was found. These results indicate that the ribs on the membrane of the current system are still not optimized to additionally work to promote local shear near the membrane surface and as turbulence promoter in the vibration mode.