Patent Application

App. No. 13/058,629

Abstract

Claims (57)

1 .- 23 . (canceled)

24 . A method of improving efficiency of microbial fermentation of a substrate that includes CO, said method comprising:

providing the substrate to a microbial culture such that

a first proportion of CO is fixed as one or more desired products including acid(s) and/or alcohol(s), and

a second proportion of CO is converted to CO 2 ,

wherein determination of the proportion of CO converted to CO 2 is used to determine a substrate supply rate for production of the one or more desired products.

25 . The method of claim 24 , wherein providing the substrate comprises providing the substrate at a supply rate that is:

i. increased if the proportion of CO converted to CO 2 is determined to be below an optimal value or range; or

ii. decreased if the proportion of CO converted to CO 2 is determined to be above an optimal value or optimal range; or

iii. maintained if the proportion of CO converted to CO 2 is determined to be substantially at an optimal value or within an optimal range.

26 . The method of claim 25 , further comprising automatically adjusting the substrate supply rate such that the proportion of CO converted to CO 2 is maintained substantially at an optimal value or range.

27 . The method of claim 24 , wherein the substrate comprising CO comprises less than 5% H 2 by volume.

28 . The method of claim 24 , wherein a desired product is ethanol.

29 . A method of improving the efficiency of producing one or more acids and/or alcohols by microbial fermentation of a substrate comprising CO under predetermined operating parameters, said method comprising

determining a proportion of carbon directed towards one or more products, and

depending on the determination, either:

i. making an adjustment to one or more operating parameters, such that the proportion of carbon fixed as a desired product increases; or

ii. maintaining the operating parameters, such that the proportion of carbon fixed as a desired product remains substantially constant.

30 . The method of claim 29 , wherein the operating parameter(s) are selected from a group consisting of:

pH of the fermentation broth;

redox potential of the fermentation broth;

CO concentration of the fermentation broth;

rate of substrate supply;

composition of the substrate stream;

pressure of the substrate stream;

fermentation broth agitation rate;

product removal rate;

acid and/or alcohol concentration of the fermentation broth;

one or more nutrients in the liquid nutrient medium; and

rate of supply of one or more nutrients.

31 . The method of claim 29 , wherein the proportion of carbon fixed as one or more products is established by determining the proportion of CO converted to CO 2 .

32 . The method of claim 29 , wherein the alcohol is ethanol and the ethanol is produced continuously.

33 . The method of claim 29 , wherein the substrate comprising CO, comprises at least about 15% to about 100% CO by volume.

34 . The method of claim 29 , wherein the fermentation is carried out by a micro-organism selected from the group consisting of Clostridium, Moorella, Pyrococcus, Eubacterium, Desulfobacterium, Carboxydothermus, Acetogenium, Acetobacterium, Acetoanaerobium, Butyribaceterium and Peptostreptococcus.

35 . The method of claim 34 , wherein the micro-organism is Clostridium autoethanogenum.

36 . The method of claim 24 , wherein the fermentation is carried out by a micro-organism selected from the group consisting of Clostridium, Moorella, Pyrococcus, Eubacterium, Desulfobacterium, Carboxydothermus, Acetogenium, Acetobacterium, Acetoanaerobium, Butyribaceterium and Peptostreptococcus.

37 . The method of claim 36 , wherein the micro-organism is Clostridium autoethanogenum.

38 . A system for the microbial fermentation of a substrate stream that includes CO to yield products that include acid(s) and/or alcohol(s), said system comprising:

a bioreactor containing, in use, a microbial culture;

measuring means adapted to determine a proportion of carbon fixed as a particular product; and

at least one adjustment means adapted to make one or more adjustments to the microbial culture and/or the substrate stream.

39 . A system according to claim 38 , wherein the measuring means comprises means for determining the composition of an exhaust stream exiting the bioreactor.

40 . A system according to claim 39 , wherein the measuring means is further adapted to determine the composition of a substrate stream entering the bioreactor.

41 . A system according to claim 38 , wherein the adjustment means are configured to make one or more adjustments if the determining means determines that the proportion of carbon fixed as a desired product has deviated from a predetermined value or range.

42 . A system according to claim 41 , wherein the adjustment means are configured to make adjustments by one or more of the following:

changing pH of the fermentation broth;

changing redox potential of the fermentation broth;

changing CO concentration of the fermentation broth;

changing H 2 concentration of the fermentation broth;

changing composition of the substrate stream;

changing pressure of the substrate stream;

changing fermentation broth agitation rate;

product removal;

changing acid and/or alcohol concentration of the fermentation broth;

changing one or more nutrients in the liquid nutrient medium; and

changing rate of supply of one or more nutrients.

43 . A system according claim 38 , further comprising processing means adapted to control one or more adjustment means such that one or more adjustment(s) can be made to the microbial culture and/or substrate stream if it is determined that the proportion of carbon fixed as a desired product has deviated from a predetermined value or range.

Assignments (8)