Develop Of New Type Membrane Module In A Membrane Bioreactor And Its Fouling Control

Based on the theory analysis of production costs,loading density,application, system processes,fouling,washing,membrane maintenance and change,which is of importance to membrane module,a kind of new type external membrane module(PVC membrane module)was developed.Using this PVC module,we improved a PVC novel membrane bioreactor,which combined some advantages of traditional side-stream membrane bioreactor.Critical flux region for module of the PVC membrane was measured with "flux step-wise method",in the condition of different recirculating flow rate and different aeration intensities.Furthermore characteristic of critical flux rang was studied.An optimal operation mode,which is high flux but low energy consumption,was found when aeration intensities increased to 1.5m³h^-1and recirculating flow rate is kept to the value of 1m³h^-1.A long-term operation of the PVC novel MBR was conducted under sub-critical and critical flux condition,while membrane online -washing was given.The conclusions is that—(1)under the sub-critical flux zone the PVC novel MBR performance is good;(2)under the critical flux zone the PVC novel MBR was working instability,while the flux decreased quickly and TMP increased highly.An improved new type membrane module(PVDF membrane module)was designed based on the former new type membrane module.At the same time,critical flux region for module of the PVDF membrane was measured in the condition of different recirculating flow rate and different aeration intensities.Furthermore characteristic of critical flux rang was studied.An optimal operation mode,which is high flux but low energy consumption,was found when aeration intensities increased to 1.5m³h^-1and recirculating flow rate is kept to the value of 1m³h^-1.A long-term operation of the PVDF novel MBR was conducted under sub-critical and critical flux condition, while membrane online-washing was given.The conclusions is that—(1)under the sub-critical flux zone the PVDF novel MBR performance is good;(2)under the critical flux zone,the flux was working stability,but TMP increased more or less in 12 hours, while the flux decreased quickly and TMP increased highly.Operation cycle effected TMP large.When operating 8 min,backwashing 30 sec,TMP increased slower;but when operating 10 min,backwashing 30 see,TMP increased quicker.Under the critical flux zone,the PVDF novel MBR was working instability.The two membrane modules were compared from the mechanical strength,the water flux,the critical flux and the operation result within backwashing-online.The conclusion is that the improved PVDF membrane module was better than the PVC module;it was successful to improve the PVC module.