A Preliminary Study On Preparation Of CS Modified Membrane And Its Application On The Treatment Of Seafood Processing Wastewater

As CS membrane in the practical application, there are poor mechanical properties, brittle, poor water resistance, readily biodegradable and not application to acidic environment, and other major issues. In view of CS chain containing -NH2and -OH, easy to chemical modification, chemical modification is used in this study to improve structure and properties of CS membrane, so that it can be better utilized for the wastewater treatment and purification.For the existing problems of Chitosan membrane, CS-lanthanum nitrate organic - inorganic membrane, CS-glutaraldehyde crosslinking membrane, CS-PVA blend membranes three CS modified membrane conditions for the preparation of optimization are studied. Through the design of the membrane preparation orthogonal test of the main process parameters on the modified membrane permeation and rejection ratio of the impact evaluation. The results showed that: Optimum CS - lanthanum nitrate organic - inorganic membrane ensures not only 93% of the high rejection ratio, but also obtain a higher flux of BSA (9.86 ml ? h-1 ? cm-2); For the optimum CS-glutaraldehyde cross-linking membrane, the flux of BSA is 9.93 ml ? h-1 ? cm-2, the rejection ratio of of BSA is up to 90%, CS - polyvinyl alcohol optimum blend membrane for the BSA flux is 8.95 ml ? h-1 ? cm-2, retention rate is 83%. And so we can know: compared to the other CS modified membrane,CS - lanthanum nitrate organic - inorganic membrane has higher flux and the retention rate.On the basis of membrane technology in the best system,a series of CS modified membrane were prepared. Through the CS modified membrane FT-IR we can know: -NH2 and -OH of CS are involved in the reaction, thus weakening hydrogen bonding between -NH2 and -OH of CS and undermining the status of the crystallization of CS membrane. So membrane can be modified to improve the mechanical strength. From the membrane can be seen in the SEM analysis, CS-glutaraldehyde crosslinking membrane and CS-PVA blend membrane on the surface are rougher than CS membrane, granular structure become larger, particles with significant pore structure, especially CS-glutaraldehyde crosslinking membrane. In contrast, CS-lanthanum nitrate hybrid membrane surface is relatively formation, and appears a larger diameter of the porous . Under the condition the different molecular weight and the amount of PEG in a series of CS - lanthanum nitrate organic - inorganic membrane SEM analysis of the details: adding PEG in casting solution of modified CS membrane have a significant impact on the surface morphology performance. In a certain range, with the increacement of molecular weight and amount of PEG, the rough surface of the membrane, the degree of particles of the membrane, particle size and micro-scale have also increased.In recent years, with the emergence of seafood processing industry,seafood processing wastewater pollution become another prominent problem. This study determined through experiments CS- lanthanum nitrate organic - inorganic membrane interception molecular weight of 60,000 to 70,000. Using this modified membrane, combining rough filtration, we can withhold organic debris and particles water-soluble proteins effectively from ankang fish, cod fish , salmon fish processing wastewater, CODcr removal rate reached 82.6% ~ 90% ,protein retention rate is over 90%.However, as seafood processing wastewater treated CODcr still relatively high , further processing can be directly discharged .the experiment for squid processing wastewater is less effective,probably due to molecular weight of substances in the wastewater smaller, relatively large membrane pore size can not be effectively interception.