DYNAMIC LONGTERM IN-SERIES RESISTANCE MODELING AND ANALYSIS OF A SUBMERGED MEMBRANE BIOREACTOR USING A NOVEL FILTRATION MODE

摘要

This study is focused on the physical filtration characteristics of a flatsheet membranebioreactor (MBR) operated under a novel filtration mode. The objective of this research wasto demonstrate the possibility of running a membrane bioreactor with high MLSSconcentration for prolonged periods without frequent blocking of the membranes. CurrentMBR designs mostly dictated by the manufacturers limit the level of MLSS that is taken as abasis for the design due to fouling problems. This restraint can be eliminated by applyinghigher shear rates and hence aeration intensity for the effective removal of cake layer fromthe surface of the membranes. A pilot scale MBR was setup at the inlet works of a domesticsewage treatment plant and was operated for 320 days. The system was operatedcontinuously with an MLSS concentration of 13,000-16,000 mg/L for 285 days without theneed for chemical cleaning. The apparent viscosity of the sludge was steady at 0.001 Pa.sthroughout the study except for the period when there was no sludge wastage and theresultant viscosity reached almost 0.004 Pa.s. Resistance components were experimentallydetermined and compared against the results of dynamic long-term simulations using the inseriesresistance model. It was found that cake resistance did not have major impact on thetotal resistance which was linked to the effective daily removal due to high shear rates.Intrinsic membrane resistance and fouling resistance were the main components contributingto total resistance having the fractions of 69% (R_m/R_t) and 30% (R_f/R_t) respectively.