Development And Study Of Novel Membrane Modules In A Membrane Bioreactor

Performance and cost of membrane module were the key factors restricting the extensive application of membrane bioreactor(MBR) technology.In order to research and develop the new membrane module with high efficiency and low energy consumption,this study focused on the development and design of the membrane module,and two novel shell-side feed hollow fiber membrane module with an air-sparging unit were designed(moduleâ… and improved moduleâ…¡),then research and tests were carried out based on this.The main test results were as follows:The clean water flux test was conducted in the selected conditions(the recirculating flowrate of 1m~3/h,1.5m~3/h and 2m~3/h),and,it was found that the relative water flux decreased with the increase of the recirculating flowrate.Critical flux zones of the two modules under different recirculating flowrate and aeration intensity were investigated with the method of flux stepwise increment.The results indicated that critical flux increased with the increase of the recirculating flowrate and aeration intensity.The impact of aeration intensity on the critical flux is higher than that of the recirculating flowrate.Critical flux zones of membrane module would have a significant reduction when the aeration intensity was lower than the recirculating flowrate.The operating conditions and running stability of the modules were investigated through the test with online back-flushing.The conclusions were as follows:For moduleâ… ,it was found that the membrane module could run stably under the conditions of the sub-critical flux zone,but it was unstable in the critical flux zone.For moduleâ…¡,the operating conditions were optimized using the method of orthogonal test.It was found that the optimal operating conditions were the recirculating flowrate of 1m~3/h,aeration rate of 1.5m~3/h,suction time of 10 minutes and back-flushing time of 10 seconds. The membrane fouling characteristics of the two modules in the continuous operation were studied.The results showed that:moduleâ… and moduleâ…¡both can run stably in the selected conditions,and,the average increasing rate of transmembrane pressure(TMP) of the two modules were 1.3153kPa/d and 1.3207kPa/d in the running time.The main design parameters,test phenomenon and test results of the two modules were compared.The comprehensive analysis showed that:the flux characteristics, economical efficiency and the membrane-fouling control performance of moduleâ…¡were better than the moduleâ… .