Study On The Pilot-scale Separation Process Of 1,3-Propanediol From Fermentation Broth

1,3-propanediol produced by microbial fermentation is an environmental-friendly process.However,there are lots of complex compositions and salts in the fermentation broth,which causes difficulties in the separation and purification process of 1,3-propanediol.In this thesis,based on 1000 t/a 1,3-propanediol pilot-scale production line in Tianguan Group,new processes for the separation of fermentation solids,salts and the purification of 1,3-propanediol were studies.Firstly,solid-liquid separation was tested with filtration of 1,3-propanediol fermentation broth using stainless steel membrane.The results indicated that under the operating conditions of inlet temperature 60?,filtration pressure 0.52/0.46 MPa and pH7.0,the filtration rate could reach 1.5 L/(min·m2)with 100nm stainless steel membrane.The removal rate of proteins reached 96.75%.The mixture of 1%NaOH and 0.5%EDTA could be used for the cleaning of metal film,and the recovery rate of water flux reached 99.99%.Secondly,electrodialysis was used to separate salts from the fermentation broth.With the flow rate of 60 L/min at 50 V,95%of salts could be removed.The mixture of 0.5%NaOH,0.05%EDTA and 0.02%MES could be used for the cleaning of ionic membrane.The results demonstrated that it was feasible to use electrodialysis for 1,3-propanediol production.Finally,distillation columns homemade by Tianguan Group was used to purify 1,3-propanediol.Under the operation conditions of top temperature 104?,top pressure-98.00 kPa and reflux ratio 2:1,the concentrated 1,3-propanediol solution with a content above 90%could be obtained.With the feed and discharge in the column and reflux ratio 5:1,99.5%1,3-propanediol product could be obtained.The results indicated that the Twin Towers Technology(distillation first and then rectifying)can be applied to the purification of 1,3-propanediol from fermentation broth.