Study On Full Recycling Of Thermostable α-amylase Fermentation Broth

With the rapid development of fermentation industry, environment problem is more and more serious. Enzyme preparation industry, as a part of fermentation industry, with the large scale fermentation, has brought environment problem which has been drawn wide attention. Now many of production enterprises control pollution by using end treatment.in our country. But because of this method with high cost and low benefit, enterprises' enthusiasm for production is not active.How to prevent and control pollution, increase the production efficiency and reduce production costs is the problem that all enterprises faced. Cleaner production provided a way for this problem.In this thesis, establishment of medium of Bacillus licheniformis was studied firstly. The optimum carbon and nitrogen sources obtained from single factor experiment was: soluble starch and ammonium sulphate. Through orthogonal experiment, the optimal condition was given for Bacillus licheniformis. The suitable medium consisted of soluble starch 2 %, ammonium sulphate 1 %, corn steep powder 0.5 %, K2HPO4 0.6 %, KH2PO4 0.3 %.On the basis of the above establishment of medium of Bacillus licheniformis, supernatant fluid from fermentation broth by centrifugal separation reused next recycle. Glucose consumption decreases with the increase of cycle of fermentation broth. The time of glucose consumption was form 36 h to 68 h. With the increase of cycle, mycelia content became more and more scarce and fermentation period became longer and longer.The results showed that closed circulation. Technique of wastewater from fermentation of Bacillus licheniformis was infeasible.The fermentation solution was filtrate by ultrafiltration concentration and the filtrate was used as processing water in next fermentation. Filtrate was reused five times, the effects of recycling the filtrate of fermentation broth on the growth of Bacillus Licheniformis was discussed. The result showed that the growth rate in filtrate recycle were faster. The filtrate that diluted to the volume before ultrafiltration was reused five times, and the result was similar to undilut. So the full filtrate recycling process of fermentation broth of Bacillus licheniformis by ultrafiltration was feasible.Thermostableα-amylase fermentation broth of Bacillus licheniformis was reused as processing water in enzyme production. Lactose content, cell growth and enzyme activity were studied in this paper, solid content was analyzed in different batches. The results showed that lactose content and enzyme activity reached dynamic balance after 2~4 circulates, and soild content also tended to a stability value in the third batch. By fully recycling the waste broth, up to 9 fermentation cycles were sustained, the average final enzyme activity in each cycle remained at a high level at 150 U/mL, compared with the first bach(129.8 U/mL). The waste fully recycling technique with ideal effect provides a new way for the cleaner production of enzyme.