| The development of ultrafiltration(UF)process for water treatment provides a new development direction.However,membrane fouling in a membrane biological pollution is still a difficult problem.The biofouling on membrane is most serious,and also the most difficult to control the pollution.Magnetic ion exchange resin(MIEX)as a adsorption material,is commonly used in water treatment and membrane combination technology is concerned by many researchers.This research compares the UF,MIEX-UF separation and MIEX alone-UF one-piece three kinds of technology,more than three kinds of technology in the study of the pollution to the irreversible cycle operating condition on the control effect and the control mechanism of difference.The test by water in the common strains of pseudomonas aeruginosa as a representative,the removal of EPS of live bacteria,not removing EPS of live bacteria and bacterial death process of ultrafiltration membrane biological pollution.Using the laser confocal microscope(CLSM)to observe the bacteria,the accumulative total of protein and polysaccharide in the membrane surface.On the basis,the mechanism of biological biofouling of MIEX-UF integrated process control was analyzed systematically.In the process of individual UF,according to single cycle run time,the most serious membrane fouling is bacterial liquid of dead bacteria,second is live bacteria that do not remove EPS and the lighter is live bacteria with removal EPS.After bacteria dead,a large number of intracellular polymers will be released,including humus,various chitosan and metabolite of other microorganisms.However,these matters result in the formation of a layer of biofilm on the surface of the membrane with microbial survival conditions,which causes serious membrane fouling.The effect of MIEX on membrane biological contamination was investigated.The results showed that the addition of MIEX significantly improved the running time.As for the live bacteria with removal EPS,live bacteria that do not remove ESP and dead bacteria,these three different contaminants,MIEX-UF membrane filtration time extend respectively 38.1%,80.0%and 181.8%compared with individual UF.Compared with the individual UF process,the integrated process of MIEX-UF can significantly reduce membrane fouling.In the process of removal of bacteria by MIEX,EPS and the intracellular polymers secreted by bacteria play an important role.The maximum removal rate of MIEX to dead bacteria is 42.51%,the second removal rate to live bacteria that do not remove ESP is 39.26%and the lowest removal rate to live bacteria with removal ESP is 26.58%.This is because that a large number of proteins and polysaccharides in the matter secreted by bacteria.The protein with negative electricity first adsorbs surface of the resin,which increases the interaction between bacteria and resin.According to the relationship between the different Zeta potential and the maximum removal rate,the results show that the removal efficiency of MIEX is increasing with the increase of electronegativity.MIEX is an anion exchange resin.The greater the electronegativity of the solution is,the easier it is to be removed by ion exchange with the Cl-on the MIEX.For three kinds of liquid,the dynamic membrane on the membrane surface formed by MIEX particles makes the greatest contribution among the control of membrane fouling by MIEX particles.They respectively occupy the total contribution of membrane fouling control 63%,58%,and 45%.In the process of integrated MIEX-UF technology,the interfacial force of MIEX-contaminants>PVDF-contaminants makes a stronger affinity between MIEX and organic matters,which will make the organic compound be captured preferentially when it crosses MIEX particle dynamic membrane.Thus reduce the amount of microorganisms and EPS that reach the membrane surface and membrane pores,which effectively remits membrane fouling. |
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