A Study On The Membrane Fouling Of An Air-lift Membrane Bio-reactor

Using the novel X-flow tubular membrane module,we developed a novel airlift recirculated MBR,which combined some advantages of both external MBR and submerged MBR.We reconstructed the aerate system of the tubular membrane module,which is the key parts of the new reactor.The change can optimize the hydraulic conditions to a maximum extent in the tubular membrane.The gas-liquid two-phase flow patterns investigated in the vertical tubular membrane module has positive effects on the flux promotion and the membrane fouling control.Clarified water flux experiments were implemented to identify the performance of the new aerate system.The influences on the membrane flux from both the temperature and the air flow rate were analyzed.A new concept gas-liquid ratio(r) in the vertical tubular membrane module was proposed for the first time.Critical flux measurements were conducted on a constant flux basis while monitoring changes in TMP by using "stepwise method".As a result,three different operational zones for MBR operation could be suggested:supra-critical zone,critical zone and sub-critical zone.Further more,effects of the aeration intensity(the gas-liquid ratio)in the the vertical tubular membrane module on critical flux were comprehensively analyzed and compared to identify the major factors influencing critical flux.A long-term operation of the MBR was conducted under sub-critical conditions. Effects of the gas-liquid ratio(r) in the vertical tubular membrane module on the mixd liquor was studied to illustrate the influence of the gas-liquid ratio(r) on the membrane fouling control.Enhanced back washes were implemented and the results suggests that the selected gas-liquid ratio(r) can obviously prolong the irreversible fouling.