Low-cost monofilament mesh filter used in membrane bioreactor process: Filtration characteristics and resistance analysis

This work investigates filtration performance of mesh filter bioreactor for synthetic municipal wastewater treatment. Critical flux is measured by flux stepping method and the effect of aeration rate on the critical flux is investigated. The long term monitoring of trans-filter pressure evolution at sub and super-critical fluxes is performed. The analysis of resistance is achieved by determination of resistances and microscopic observation of bio-cake. Cake resistance values vary from 78% to 92% of total filtration resistance for sub and super-critical fluxes. The effect of variations of specific aeration demands (SADm: 0.5–6 m3/m2 h) on suspended solid of effluent, turbidity of filtrate, filtration resistance, and zeta potential of biomass is evaluated. The results show that filtrate quality is decreased when the aeration rate increases. It is attributed to stable formation of dynamic membrane. A rather clear filtrate, less than 18 NTU of turbidity, is obtained for SADm 0.5 m3/m2 h. The results also show that the total filtration resistance of the sub-critical flux significantly decreases with increasing aeration intensity until SADm 2 m3/m2 h and thereafter slightly decreases. It is also shown that the variations of zeta potential of biomass with aeration rate highly correspond to the alterations of filtration resistance.

► To investigate filtration characteristics of low-cost mesh filter used in MBR.
► To determine critical flux and trans-filter pressure at sub/super critical fluxes.
► To determine resistances, i.e., mesh, cake, and gel and to utilize SEM technique.
► To develop optimal aeration intensity for secondary membrane formation.
► To correspond zeta potential of sludge to hydraulic resistance with aeration rates.