Water treatment with free-bubbling corrugated sheet MBR

Abstract

Having previously introduced a new type corrugated-sheet membrane bioreactor (CS-MBR) with slug bubbling, this work investigates its water treatment performance and hydrodynamic optimization under a free bubbling regime. Experiments in parallel were conducted to compare CS-MBR with flat sheet membrane bioreactor (FS-MBR). The transmembrane pressure (TMP) and permeability results indicate that the corrugated sheet membrane has better anti-fouling performance with a final flux after 15 days of operation that was 45 % higher than that of the flat sheet membrane that had been tested in parallel. The analysis results of effluent quality and sludge extracellular polymeric substances (EPS) indicate that the membrane configuration has little impact on the effluent quality and sludge properties in the system. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) revealed the accumulation pattern of foulants on the surface of the corrugated sheet membrane and suggested that the corrugations were the cause of the improved anti-fouling performance. Bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) was extracted from fouling example at membrane surfaces, which was 50 % lower in the CS-MBR than in the FS-MBR. Computational Fluid Dynamics (CFD) simulations showed that channel gap distance of 2– 4 mm combined with 20 m/s nozzle velocity could produce an intense hydrodynamic effect. Based on the traditional free bubbling air usage, total air consumption of this CS-MBR optimal design is expected to save up to 70 % on energy.