Method for producing a chemical product and continuous fermentation apparatus

Abstract

To control flow velocity of a culture liquid inside a membrane separation tank without giving influences to culture conditions in the fermentation tank, and also suppress precipitation of microorganisms or culture cells so that the production efficiency of the chemical product can be improved, in a method for producing a chemical product including the steps of: cultivating microorganisms or culture cells in a fermentation tank; transferring a culture liquid from the fermentation tank to a membrane separation tank so as to filter the culture liquid through a separation membrane; and collecting a fermentation product from a filtration liquid as the chemical product while refluxing an unfiltered culture liquid that has not been filtered so as to be joined to the culture liquid on an upstream side of the membrane separation tank, one portion of the culture liquid to be transferred from the fermentation tank is allowed to bypass the membrane separation tank depending on a pressure at the culture liquid flow-in side of the membrane separation tank.

1 . A method for producing a chemical product including the steps of: cultivating microorganisms or culture cells in a fermentation tank; transferring a culture liquid from the fermentation tank to a membrane separation tank so as to filter the culture liquid through a separation membrane; and collecting a fermentation product from a filtration liquid as the chemical product while refluxing an unfiltered culture liquid that has not been filtered so as to be joined to the culture liquid on an upstream side of the membrane separation tank, wherein one portion of the culture liquid to be transferred from the fermentation tank is allowed to bypass the membrane separation tank depending on a pressure at the culture liquid flow-in side of the membrane separation tank. 
     
     
         2 . The method for producing a chemical product according to the above-mentioned  claim 1 , in which a flowing quantity of the culture liquid to be allowed to bypass the membrane separation tank is controlled so that a gauge pressure at the culture liquid flow-in side of the membrane separation tank is set to 1 MPa or less. 
     
     
         3 . The method for producing a chemical product according to the above-mentioned  claim 1 , in which one portion of the unfiltered culture liquid is refluxed so as to be joined to the culture liquid in the fermentation tank, while the rest of the portion of the unfiltered culture liquid is refluxed so as to be joined to a culture liquid located between the fermentation tank and the membrane separation tank. 
     
     
         4 . The method for producing a chemical product according to the above-mentioned  claim 3 , in which a flowing quantity of the unfiltered culture liquid to be refluxed so separation tank and a flowing quantity of the unfiltered culture liquid to be relaxed so as to be joined to the culture liquid in the fermentation tank are each independently controlled. 
     
     
         5 . The method for producing a chemical product according to the above-mentioned  claim 3 , in which a ratio of a flowing quantity of the unfiltered culture liquid to be refluxed so as to be joined to the culture liquid in the fermentation tank to a flowing quantity of the unfiltered culture liquid to be refluxed so as to be joined to the culture liquid located between the fermentation tank and the membrane separation tank is set to 1 or less. 
     
     
         6 . The method for producing a chemical product according to the above-mentioned  claim 1 , in which each of the linear speed of the culture liquid to be transported from the fermentation tank to the membrane separation tank, the linear speed of the unfiltered culture liquid that is refluxed from the membrane separation tank so as to be joined to the culture liquid on the upstream side of the membrane separation tank and the linear speed of the culture liquid that is allowed to bypass the membrane separation tank is set to 2.5 cm/sec or more. 
     
     
         7 . The method for producing a chemical product according to above-mentioned  claim 1 , in which a quantity of culture liquid to flow into the membrane separation tank and/or a quantity of filtration liquid from the separation membrane are adjusted so that the recovery percentage of the quantity of filtration liquid from the separation membrane to the quantity of culture liquid to flow into the membrane separation tank is set to 10.0% or less. 
     
     
         8 . The method for producing a chemical product according to the above-mentioned  claim 1 , in which a ratio of the culture liquid volume in the fermentation tank to as culture liquid volume in the membrane separation tank is set in a range from 4 or more to 100 or less. 
     
     
         9 . A continuous fermentation apparatus including: a fermentation tank for cultivating microorganisms or culture cells; a membrane separation tank having a separation membrane used for collecting a fermentation product produced in a culture liquid from the fermentation tank; a circulation line that connects the fermentation tank with the membrane separation tank so as to transfer the culture liquid to the membrane separation tank, and refluxes an unfiltered culture liquid that has not been filtered through the separation membrane so as to be joined to the culture liquid on the upstream side of the membrane separation tank; and a culture liquid transfer means installed in the circulation line, in which this structure further includes a bypass line for the membrane separation tank; a detection means for a pressure at the culture liquid flow-in side of the membrane separation tank; and a flowing quantity control means installed in the bypass line. 
     
     
         10 . The continuous fermentation apparatus according to the above-mentioned  claim 9 , in which the flowing quantity control means is operated in response to the detection result of the detection means. 
     
     
         11 . The continuous fermentation apparatus according to the above-mentioned  claim 9 , further including a linear speed detection means for the circulation line so that the flowing quantity control means and/or the culture liquid transfer means are operated in response to the detection result of the linear speed detection means. 
     
     
         12 . The continuous fermentation apparatus according to the above-mentioned  claim 9 , in which the membrane separation tank is set up in a circulation circuit having a liquid transfer means different from the culture liquid transfer means, which is independent from the fermentation tank. 
     
     
         13 . The continuous fermentation apparatus according to the above-mentioned  claim 9 , in which the circulation line has an opening at a position that is immersed with the culture liquid to be stored in the fermentation tank. 
     
     
         14 . The continuous fermentation apparatus according to the above-mentioned  claim 9 , in which the ratio of the fermentation tank volume to the membrane separation tank volume is set ina range from 4 or more to 100 or less.