Effect Of Crystallization Technology On Glutamic Acid Extraction

The pollution problem is so serious that puzzles MSG industry many years, especially"isoelectric point-ion exchange"process. In this paper, the basic properties, behavior of residual microcrystal in industry glutamic acid mother liquid, especially secondary extraction of glutamic acid which is the key technology of"Glutamic acid extraction of non-waste process with double crystallization"are studied. This new process can be a solution to deal with the high cost and waste made from"isoelectric point-ion exchange"process.The effect of ammonium sulfate, glucose and bacteria cell with solubility of glutamic acid in isoelectric mother liquid is studied. Furthermore, the affection of extraction rate with such substances is analyzed. Because of the affect of the impurities, the higher the temperature increases more glutamic acid dissolves in water. The extraction rate will reduce by 3.6 percentage points, when the Glutamic acid concentration is 10% in fermentation liquid. Based on the solubility of glutamic acid in water, the one-step crystallization extraction rate should be 94.5% theoretically and 90.9% considering the affect of impurities. However, the real extraction rate is only 78 to 80%. So there would be some other factors that cause the reducibility of one-step isoelectric point extraction rate.The shape, particle size and sedimentation property of crystal particle are discussed through experiments and theory. The apparent solubility and real solubility are defined which are expression used to describe the crystal property of isoelectric point liquid. It is found that the stable existence of microcrystal is the main cause of reducibility of extraction rate. Because of the existing of microcrystal size of 0.3 to 7.1μm, the one-step isoelectric point extraction rate reduces by 7 percentage point. The crystal sedimentation speed and distance is calculated according to which only the microcrystal size of 55.4μm can subside to the bottom of 5 meter-high crystallizer in 6 hours. Such study can provide basic data on how to design a new crystallizer with microcrystal eliminating function.The process of flocculation cell removing is optimized, which is heating at 120℃for 5min at pH 3.0 adding 42ppm sodium polyacrylate. With this process the isoelectric mother liquid can be dealed clearly.The reasonable process of secondary crystallization is explored, with which the cost and wastewater can be reduced. The secondary extraction rate can reach to 70% and particle purity reach to 90%.Above all, the"Non-waste double extraction technology of Glutamic acid"process is basically shaped, meanwhile, the cost and process waste water is well limited. It can be tested in industrial scale amplifying.