Research On The Operation Process Of Immersion Ultrafiltration Membrane

In order to reduce the energy consumption and control the membrane fouling,a novel submerged membrane separation process was developed in this paper.In this design,the traditional aeration device was replaced by a low-power motor.Through the traction force produced by the motor,the membrane module can move up and down in the water.In this case,friction will be created between membrane surface and water.The friction can prevent the deposition of pollutants on the membrane surfaces and then control the membrane fouling.The homemade mixed liquid was used as membrane fouling simulated solution.In the case of a constant flux of 20.0 L/(m2·h),a response surface experiment was designed to optimize the parameters of the lifting process.Also,in order to confirm the effect of controlling membrane fouling of lifting process,a comparison of the filtration resistance and transmembrane pressure were set out of the new lifting process and the traditional aeration process.A membrane fouling simulation solution was prepared according to the composition of the activated sludge mixture.The experimental results showed that the composition of the simulation solution was:50 mg/L sodium alginate,25 mg/L humic acid,6 g/L kaolin and 0.8 g/L PEO.During the process of our research,a preservative of Kathan was added into the simulation solution regularly,all those ensure the simulated solution a constant membrane fouling ability and a suitable liquid for subsequent studies.Run the lifting process to filter the simulation solution,and a response surface experiment was designed to optimize the parameters of the lifting process on the basis of the single factor test.The effect of longitudinal displacement of the fiber,bending displacement of the fiber,lifting speed of the fiber,and transverse displacement of the module on the transmembrane pressure was studied.The results showed that the optimal parameters of the lifting process were as follows:the longitudinal displacement of the fiber was 18 cm,the bending displacement of the fiber was 10 cm,the lifting speed of the fiber was 10 cm/s,the transverse displacement of the module was 14 cm.The transmembrane pressure of the lifting process under these optimal parameters was 18.90 kPa,preliminary indicating that the lifting process proposed in this paper can slowing down the rate of membrane fouling during submerged membrane separation technology.In order to further confirm the effect of controlling membrane fouling of lifting process,a comparison of the filtration resistance and transmembrane pressure were set out of the new lifting process and the traditional aeration process.After a 64 min filtration operation,compared to the aeration process,the cake layer resistance of the lifting process reduced by about 13.6%.For a 120 min filtration operation,transmembrane pressure of the lifting process was 11.1%lower than that of aeration process at the end of filtration.According to the long-time operation,the stable running time was increased from 352 min of the aeration process to 408 min of the lifting process.All these suggesting that the novel lifting process can control membrane fouling more effectively than the aeration process.Therefore,the lifting process is an efficient and feasible membrane separation technology.