Process control for bioconversion.

Abstract

A control process for enhancing a biological process for converting a gaseous substrate to a useful end product, e.g., ethanol, is provided. The process includes feeding a gaseous substrate, including one or more of CO and CO, to a bioreactor at a substrate addition rate. Acetogenic bacteria fed to the bioreactor ferment the gaseous substrate in a fermentation broth. The process includes determining the concentrations of carboxylic acids and / or carboxylates in the fermentation broth. A control algorithm uses these concentrations to adjust the addition rate of the gaseous substrate.

Description

[Technical Field]

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 961,743, filed January 16, 2020, the entire contents of which are incorporated herein by reference. A process for the bioconversion of a gaseous substrate comprising carbon monoxide is provided. More specifically, the process comprises controlling the bioconversion of the gaseous substrate by controlling the rate of addition of the gaseous substrate using the concentration of carboxylic acids and / or carboxylates. [Background technology]

[0002] Carbon monoxide production occurs not only from natural processes but also from industrial processes, including the burning of fossil fuels such as coal, oil, and natural gas, which contribute to an ever-increasing amount of carbon emissions into the environment. Control of fermentation is often based on manual measurements and adjustments based on the results of such measurements. Such manual processes can have a certain time lag between measurements and adjustments, resulting in inefficient fermentation. Furthermore, the use of more automated control strategies can provide more precise control, faster response times, and lower labor costs. Considering the large amount of carbon monoxide (CO) generated, there is a need for a bacterial fermentation system that can efficiently utilize CO. Summary of the Invention

[0003] The process includes feeding a gaseous substrate containing CO to a bioreactor at a substrate addition rate. The acetogenic bacteria fed to the bioreactor ferment the gaseous substrate in a fermentation broth. The process of the present invention comprises: M determining the concentration of A M are the concentrations of carboxylic acids and carboxylates. The control algorithm determines A M is used to adjust the rate of addition of the gaseous substrate.

[0004] So that the above-mentioned features of the present disclosure may be understood in detail, a more particular description of the present disclosure briefly summarized above can be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that since the present disclosure may admit of other equally effective embodiments, the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be considered as limiting the scope of the present disclosure. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 shows a bioreactor system. [Figure 2] FIG. 2 is a graph comparing the STY values ​​of ethanol in an automated controlled process with the STY values ​​of ethanol in a non-automated controlled process. [Figure 3] FIG. 3 is a graph comparing cell density values ​​in an automated controlled process with cell density values ​​in a non-automated controlled process. [Figure 4] FIG. 4 is a flow chart that provides an overall overview of the process control methodology. [Figure 5] FIG. 5 is a flow chart illustrating the process control methodology for the acid controller. [Figure 6] FIG. 6 is a flow chart illustrating another embodiment of a process control methodology for an acid controller. [Figure 7] FIG. 7 is a flow chart illustrating a process control methodology for a gas flow controller. [Figure 8] FIG. 8 is a flow chart illustrating another embodiment of a process control methodology for a gas flow controller. DETAILED DESCRIPTION OF THE INVENTION

[0006] The following description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of exemplary embodiments. The scope of the present disclosure should be determined with reference to the claims. definition Unless otherwise defined, the following terms used throughout this specification for the purposes of this disclosure are defined as follows and can include either the singular or plural form of the definition defined below. The term "about" modifying any quantity refers to the variation in quantities encountered in real-world situations, such as in a laboratory, pilot plant, or production facility. For example, the amount of a component or measure used in a mixture or amount, when modified by "about," includes the degree of variation and caution normally used when measuring under experimental conditions in a production plant or laboratory. For example, the amount of a component of a product, when modified by "about," includes batch-to-batch variation in multiple experiments in a plant or laboratory, and the variation inherent in analytical methods. Whether modified by "about," an amount includes equivalents to the amount. Any amount stated herein that is modified by "about" can also be used in this disclosure as the amount not modified by "about."

[0007] The term "fermentor" includes a fermenter / bioreactor consisting of one or more vessels and / or columns, or piping, including a batch reactor, a semi-batch reactor, a continuous reactor, a continuous stirred tank reactor (CSTR), a bubble column reactor, an external recycle loop reactor, an internal recycle loop reactor, an immobilized cell reactor (ICR), a trickle bed reactor (TBR), a moving bed biofilm reactor (MBBR), a gas lift fermentor, a membrane reactor such as a hollow fiber membrane bioreactor (HFMBR), a static mixer, a gas lift fermentor, or other vessel or other device suitable for gas-liquid contact. The terms "fermentation," "fermentation process," or "fermentation reaction," etc., are intended to encompass both the growth phase and the product biosynthesis phase of the process. In one aspect, fermentation refers to the conversion of CO to a carboxylic acid. In another aspect, fermentation refers to the conversion of CO to an alcohol. In yet another aspect, fermentation refers to the conversion of CO to an alcohol and a carboxylic acid. The term "cell density" means the mass of microbial cells per unit volume of fermentation broth, e.g., grams / liter.

[0008] As used herein, productivity is expressed as STY. In this embodiment, productivity STY (space-time yield) is expressed as alcohol STY (g ethanol / (liter) * It can be expressed as As used herein, "oxygenated hydrocarbon compounds" can include compounds containing carbon, H2, and oxygen, such as, for example, ethanol and butanol. In one embodiment, the system may include one or more bioreactors configured to receive a gaseous substrate. The one or more bioreactors may contain a fermentation broth containing acetogenic bacteria and a fermentation medium. The fermentation control system may include a sampling device configured to isolate a sample of the fermentation broth from the bioreactor and an analyzer configured to analyze the isolated sample. The system may include a controller configured to control the rate of addition of the gaseous substrate, the rate of addition of the gaseous substrate being based, at least in part, on the concentrations of carboxylic acids and carboxylates determined by the analyzer. A further aspect relates to a computer program product including a non-transitory computer-readable medium having a computer program embodied therein. Such computer program includes instructions for causing a processor to execute the steps necessary to carry out the control process described herein. Such process includes receiving information for input to a controller configured to control the rate of addition of the gaseous substrate. Such received and input information includes information received from an analyzer configured to analyze samples from the bioreactor.

[0009] Bioreactor systems for conversion of gaseous substrates The process may utilize bioreactor systems such as those described in U.S. Patent Application Nos. 16 / 530,481 and 16 / 530,502, both filed August 2, 2019, U.S. Patent Application No. 13 / 471,858, filed May 15, 2012, U.S. Patent Application No. 13 / 471,827, filed May 15, 2012 (U.S. Patent No. 9,976,158, issued May 22, 2018), and U.S. Patent Application No. 13 / 473,16, filed May 16, 2012 (U.S. Patent No. 8,592,19, issued November 26, 2013), all of which are incorporated herein by reference. One embodiment of a bioreactor system is shown in Figure 1. The system may include a bioreactor 101 adapted to ferment a gaseous substrate supplied by a gaseous substrate addition line 103. The system allows for the discharge of off-gas from the bioreactor 101 through an off-gas discharge line 105. The bioreactor 101 may be supplied with nutrients from a nutrient feed tank 107. 1 , fermentation broth may be removed from bioreactor 101 through fermentation broth draw line 113 and fed to microfiltration or ultrafiltration 115. At least a portion of the cells from microfiltration or ultrafiltration 115 may be returned to bioreactor 101 through cell return line 133. Permeate may be conveyed from microfiltration or ultrafiltration 115 through permeate line 117 to distillation feed tank 119 and then to distillation column 121. Distillation column 121 provides distillation product 135 and water (distillation bottoms), which may be returned to bioreactor 101 through water return line 123. In one embodiment, the permeate from permeate line 117 may be analyzed by acid controller 125. Acid controller 125 may provide a signal (shown as dashed signal line 127) to gas flow controller 129.

[0010] Gaseous Substrates The gaseous substrate may comprise CO. More specifically, the gaseous substrate may be a CO-containing substrate or a combination of a CO-containing substrate and a CO2-containing substrate. CO-containing substrate The CO-containing substrate may include any gas containing CO. In this embodiment, the CO-containing gas may include synthesis gas, industrial gas, and mixtures thereof. In a related embodiment, the gaseous substrate may include, in addition to CO, nitrogen gas (N), carbon dioxide (CO), methane gas (CH), synthesis gas, and combinations thereof. The synthesis gas may be provided from any known source. In one embodiment, the synthesis gas may be provided from the gasification of carbonaceous materials. Gasification involves the partial combustion of biomass in an oxygen-limited atmosphere. The resulting gas may contain CO and H2. In this embodiment, the synthesis gas will contain at least about 10 mol% CO, in one embodiment at least about 20 mol%, in one embodiment from about 10 to about 100 mol%, in another embodiment from about 20 to about 100 mol% CO, in another embodiment from about 30 to about 90 mol% CO, in another embodiment from about 40 to about 80 mol% CO, and in another embodiment from about 50 to about 70 mol% CO. Some examples of suitable gasification methods and apparatus are provided in U.S. Patent Application Nos. 61 / 516,667, 61 / 516,704, and 61 / 516,646, all filed April 6, 2011, and U.S. Patent Application Nos. 13 / 427,144, 13 / 427,193, and 13 / 427,247, all filed March 22, 2012, all of which are incorporated herein by reference.

[0011] In another embodiment, the process has applicability in supporting the production of alcohols from gaseous substrates, such as industrial gases containing large amounts of CO. In some embodiments, the CO-containing gas is derived from carbonaceous waste, e.g., industrial waste gas, or from the gasification of other waste materials. Thus, the process represents an effective process for capturing carbon that would otherwise be emitted into the environment. Examples of industrial gases include gases produced during the manufacture of ferrous metal products, non-ferrous product manufacturing, petroleum refining processes, coal gasification, biomass gasification, power production, carbon black production, ammonia production, methanol production, coke production, and gas reforming. In another embodiment, H2 may be sourced from industrial waste gases or from the gasification of other waste materials. Therefore, the process represents an effective method for capturing H2 that would otherwise be emitted into the environment. Examples of industrial gases include gases produced during the manufacture of ferrous metal products, non-ferrous product manufacturing, petroleum refining processes, coal gasification, biomass gasification, power production, carbon black production, ammonia production, methanol production, and coke production. Other sources of H2 include, for example, electrolysis of H2O and bio-generated H2.

[0012] Depending on the composition of the CO-containing substrate, the CO-containing substrate may be provided directly to the fermentation process or may be further modified to contain an appropriate molar ratio of H to CO. In one embodiment, the CO-containing substrate fed to the fermentor has a molar ratio of H to CO of about 0.2 or greater, in another embodiment, about 0.25 or greater, and in another embodiment, about 0.5 or greater. In another embodiment, the CO-containing substrate fed to the fermentor may contain about 40 molar% or greater CO plus H and about 30 molar% or less CO, in another embodiment, about 50 molar% or greater CO plus H and about 35 molar% or less CO, and in another embodiment, about 80 molar% or greater CO plus H and about 20 molar% or less CO. In one embodiment, the CO-containing substrate comprises CO and H. In this embodiment, the CO-containing substrate will contain at least about 10 mol% CO, in one embodiment at least about 20 mol% CO, in one embodiment about 10 to about 100 mol% CO, in another embodiment about 20 to about 100 mol% CO, in another embodiment about 30 to about 90 mol% CO, in another embodiment about 40 to about 80 mol% CO, and in another embodiment about 50 to about 70 mol% CO.

[0013] In one embodiment, a gas separator is provided to substantially separate at least a portion of the gas stream (that portion comprising one or more components). For example, a gas separator can separate CO from a gas stream comprising the following components: CO, CO, and H, and can transfer the CO to a CO storage location, while transferring the remaining gas stream (including CO and H) to a bioreactor. Any gas separator known in the art can be utilized. In this embodiment, the syngas fed to the fermentor will have about 10 mol% CO or less, in another embodiment about 1 mol% CO or less, and in another embodiment about 0.1 mol% CO or less. Some gas streams may contain high concentrations of CO and low concentrations of H. In one embodiment, it may be desirable to optimize the composition of the substrate stream to achieve more efficient alcohol production and / or overall carbon capture. In another embodiment, the concentration of H in the substrate stream may be increased before the substrate stream is transferred to the bioreactor.

[0014] According to certain embodiments of the present disclosure, streams from two or more sources can be combined and / or blended to produce a desired and / or optimized substrate stream. For example, a stream containing a high concentration of CO, such as off-gas from a steel mill converter, can be combined with a stream containing a high concentration of H, such as off-gas from a steel mill coke oven. Depending on the composition of the gaseous CO2-containing substrate, it may be desirable to treat the gaseous CO2-containing substrate to remove any undesirable impurities, e.g., dust particles and chemical impurities such as cyanide and oxygen, before introducing the gaseous CO2-containing substrate into the fermentation. For example, the gaseous substrate can be filtered or scrubbed using known methods.

[0015] Acetogenic bacteria The process involves carrying out fermentation in a fermentation bioreactor using acetogenic bacteria. Examples of useful acetogens include acetogens of the genus Clostridium, such as strains of Clostridium ljungdahlii, including those described in WO 2000 / 68407, EP 117309, U.S. Pat. Nos. 5,173,429, 5,593,886 and 6,368,819, WO 1998 / 00558 and WO 2002 / 08438, strains of Clostridium autoethanogenum (DSMZ Germany DSM 10061 and DSM 19630), including those described in WO 2007 / 117157 and WO 2009 / 151342, U.S. Pat. No. 7,704,723 and "Biofuels and Suitable acetogenic bacteria include Clostridium ragsdalei (P11, ATCC BAA-622) and Alkalibaculum bacchi (CP11, ATCC BAA-1772), each of which is described in "Bioproducts from Biomass-Generated Synthesis Gas," by Hasan Atiyeh, presented in the Oklahoma EPSCoR Annual State Conference, April 29, 2010, and Clostridium carboxidivorans (ATCC PTA-7827), which is described in U.S. Patent Application Publication No. 2007 / 0276447. Other suitable microorganisms include those of the genus Moorella (including Moorella sp. HUC22-1) and those of the genus Carboxydothermus. Each of these publications is incorporated herein by reference. Mixed cultures of two or more microorganisms may also be used.

[0016] Additional examples of useful acetogens include Acetogenium kivui, Acetoanaerobium noterae, Alkalibacrum bacchii CP11 (ATCC BAA-1772), Blautia producta, Butyribacterium methylotrophicum, Caldanaerobacter subterraneous, Caldanaerobacter subterraneous pacificus, Carboxydothermus hydrogenoformans, Clostridium aceticum, and Clostridium acetobutylicum. acetobutylicum, Clostridium acetobutylicum P262 (DSM19630, DSMZ Germany), Clostridium autoethanogenum (DSM19630, DSMZ Germany), Clostridium autoethanogenum (DSM10061, DSMZ Germany), Clostridium autoethanogenum (DSM23693, DSMZ Germany), Clostridium autoethanogenum (DSM24138, DSMZ Germany), Clostridium carboxydivorans P7 (ATCC PTA-7827), Clostridium coskatii (ATCC PTA-10522), Clostridium drakei, Clostridium ljungdahlii PETC (ATCC 49587), Clostridium ljungdahlii ERI2 (ATCC 55380), Clostridium ljungdahlii C-01 (ATCC 55988), Clostridium ljungdahlii O-52 (ATCC 55889), Clostridium magnum, Clostridium pasteurianumpasteurianum (DSM525 from DSMZ Germany), Clostridium ragsdali P11 (ATCC BAA-622), Clostridium scatologenes, Clostridium thermoaceticum, Clostridium ultunense, Desulfotomaculum kuznetsovii, Eubacterium limosum, Geobacter sulfurreducens, Methanosarcina acetivorans, Methanosarcina barkeri, Moorella thermoacetica thermoacetica, Moorella thermoautotrophica, Oxobacter pfennigii, Peptostreptococcus productus, Ruminococcus productus, Thermoanaerobacter kivui, Clostridium sticklandii, and mixtures thereof.

[0017] Fermentation medium In one embodiment, the fermentation process begins with the addition of a medium to the reactor vessel. Some examples of medium compositions are described in U.S. Patent Application Nos. 61 / 650,098 and 61 / 650,093, filed May 22, 2012, and U.S. Patent No. 7,285,402, filed July 23, 2001, all of which are incorporated herein by reference. The medium can be sterilized to remove undesirable microorganisms, and the reactor is inoculated with the desired microorganisms. Sterilization is not required. In another embodiment, the concentrations of various media components for use with acetogenic bacteria are as follows: [Table 1] In one embodiment, the medium comprises less than about 0.01 g / L yeast extract and less than about 0.01 g / L carbohydrates.

[0018] Fermentation Control Control methodologies, which can be automated, can enhance biological processes for converting gaseous substrates into useful end products, such as ethanol. For example, automated control strategies can increase productivity by 300% or more compared to processes without automated control strategies. Fermentations conducted in bioreactors using the media and acetogenic bacteria described herein, employing the fermentation control methodology described herein, are effective to provide an STY (space-time yield) of at least about 100 g ethanol / (L·day). Possible STY values ​​include about 100 g ethanol / (L·day) to about 300 g ethanol / (L·day), in another embodiment, about 100 g ethanol / (L·day) to about 250 g ethanol / (L·day), and in another embodiment, about 100 g ethanol / (L·day) to about 200 g ethanol / (L·day). A comparison of STY values ​​using an automated control system as described herein (shown as 201 and 203) with STY values ​​using a manual control system (shown as 205 and 207) is shown in FIG. 2. In another embodiment shown in FIG. 2, the automated control system was able to improve STY more quickly than the manual system. In this embodiment, the A in the fermentation broth was significantly increased. M determining the concentration of A; M The step of adjusting the rate of addition of the gaseous substrate using the above in a control algorithm is completed in less than 30 minutes, in another embodiment, from about 0.1 seconds to about 30 minutes, in another embodiment, from about 0.1 seconds to about 20 minutes, in another embodiment, from about 0.21 seconds to about 10 minutes, in another embodiment, from about 0.1 seconds to about 1 minute, and in another embodiment, from about 1 second to about 5 minutes.

[0019] Using the fermentation control methodology described herein, fermentations conducted in bioreactors using the media and acetogenic bacteria described herein are effective to provide cell densities of at least about 1 gram / liter, in another embodiment, about 1 to about 50 grams / liter, and in another embodiment, about 3 to about 30 grams / liter. A comparison of cell density values ​​using an automated control system as described herein (shown as 301 and 303) with cell density values ​​using a manual control system (shown as 305 and 307) is shown in Figure 3. In another embodiment shown in Figure 3, the automated control system was able to increase cell density more quickly than the manual system. The process control methodology is illustrated in Figures 4-8. Various control aspects are shown in these figures. The various control aspects can be combined in any manner to provide an overall process control methodology. An overall overview of the process control methodology is shown in FIG. 4. In this embodiment, the process includes feeding a gaseous substrate, including one or more of CO and CO, to a bioreactor at a gaseous substrate addition rate. Acetogenic bacteria in the bioreactor ferment the gaseous substrate in a fermentation broth. The process includes determining the acid concentration in the fermentation broth from a fermentor using an acid concentration measurement. A gas controller adjusts the gaseous substrate addition rate to achieve a target range of acid concentration. The measured acid concentration is the concentration of a carboxylic acid, a carboxylate, or a combination of a carboxylic acid and a carboxylate. The fermentation broth can be used directly for acid measurement. In another embodiment, a permeate can be formed from the fermentation broth, and the acid concentration in the permeate can be determined. The acid concentration measurement can be performed using any of the analytical techniques described herein.

[0020] Another embodiment of a process control methodology for an acid controller is shown in Figure 5. In this embodiment, the controller inputs include a setpoint for the acid concentration and a measured value for the acid concentration. The inputs may be used in a control algorithm provided by a controller with integral action. The controller provides an output of a gas flow target. Another embodiment of a process control methodology for an acid controller is shown in Figure 6. In this embodiment, the controller inputs include a setpoint for the acid concentration and a measured value for the acid concentration. The inputs may be used in a control algorithm provided by a controller with integral action. A linear to exponential transformation may be applied to provide an output for the gas flow target value. Another embodiment of a process control methodology for a gas controller is shown in Figure 7. In this embodiment, a gas flow target value input is provided to a gas flow controller, which controls the gas flow to the fermentor. Another embodiment of a process control methodology for a gas controller is shown in Figure 8. In this embodiment, the controller inputs include a gas flow target input and a measured gas flow. The inputs may be used in a control algorithm provided by a controller with integral action. The controller operates to control a gas flow controller. The gas flow controller provides a gas flow to fermentor output.

[0021] sampling The fermentation broth can be removed directly from the bioreactor. Sample lines from the bleed stream or other stream for removing the fermentation broth can be fluidly connected to appropriate analytical equipment for online measurements. A sampling system for online analysis from one or more reactors can include suitable conduits (e.g., tubing or piping), valves, pumps, and actuators to allow automated sampling of desired bioreactors at desired times, as well as suitable equipment for flushing (purging) the sample lines. In one embodiment, the process includes performing the analysis on a permeate that is free or substantially free of bacterial cells as a result of filtration or membrane separation. A permeate stream can be obtained from the cell separation system and used for the analysis. Sample conditioning methods, such as carbon filtration, temperature control, bubble removal, and combinations of one or more sample conditioning methods, can be used. The fermentation broth can be measured continuously or intermittently, for example, periodically with a period between each successive measurement, typically from 0.1 seconds to 10 minutes, in one embodiment from 0.1 seconds to 5 minutes, in one embodiment from every 0.1 seconds to every 120 seconds, in one embodiment from every 0.5 seconds to every 60 seconds, and in another embodiment from every 1 second to every 10 seconds.

[0022] Determination of carboxylic acids and carboxylates In one embodiment, the process comprises the step of: M determining the concentration of A M is the concentration of carboxylic acid and carboxylate. The process includes a step of determining the concentration of carboxylic acid and carboxylate using an analytical device selected from the group consisting of near-infrared spectroscopy (NIR), gas chromatography, high-pressure liquid chromatography, mass spectrometry, and combinations thereof. In one embodiment, the carboxylic acid and / or carboxylate in the permeate are measured by NIR. The NIR may be an in-line type that allows for continuous measurement. Useful NIR frequencies include, in one embodiment, about 800 to 2200 nm, in another embodiment, about 1280 to about 2184 nm, in another embodiment, about 1640 to about 1724 nm, in another embodiment, about 1630 to about 1910 nm, and in another embodiment, about 870 to about 2184 nm. Control Algorithm In one embodiment, the control methodology as described herein is automated and involves the use of a computer program having suitable instructions to cause a processor to send the necessary signals to a controller to carry out the control methodology.

[0023] In one embodiment, A provided by measuring carboxylic acids and carboxylates M The value is used in a control algorithm to adjust the rate of substrate addition. In this embodiment, the control algorithm is represented by Equation I term =E int / I by I term wherein I is a constant and wherein E int =(previous E int )+(A M -A T ) * dt (where dt is the A in the permeate) M is the time interval between determining the previous E int and E int are the values ​​at the beginning and end, or at the time interval dt). The control algorithm is term =(A M -A T ) * P by P term wherein A T are the target concentrations of carboxylic acids and carboxylates, and P is a constant. Additionally, the control algorithm uses the formula E int =(Previous E int )+(A M -A T ) * E by dt int where dt is the A in the permeate. M is the time interval between determining the previous E int and E int is a value at the beginning and end, or a value at the time interval dt; term =E int / I by I term wherein I is a constant; and output =P term +I term By controller outputThe method further includes determining the constants I and P. The constants I and P are determined based on the process conditions and / or equipment. In this embodiment, P may be 0 to 50, in another embodiment, about 1 to about 30, and in another embodiment, about 3 to about 10. I may be about 100 to about 10,000, in another embodiment, about 500 to about 5000, and in another embodiment, about 800 to about 2500. The values ​​and ranges of the controller tuning constants I and P are appropriate according to the following conditions: time increment ("dt"): in seconds; acid measurement (and acid error): in g / L total acid; and the controller output is then indexed to map the linear span of the controller output from 0 to 100 to an exponential span of GFR from the initial GFR of 10% required under inoculated conditions (about 1 g / L cell concentration) to the GFR of about 150% required at high productivity steady state. The use of different time units (eg, minutes), acid measurement units (eg, ppm), or indexing spans will result in different suitable values ​​and ranges for the controller tuning constants and exponential constants.

[0024] The controllers used in the system can include I controllers, PI controllers, ID controllers, and PID controllers. During fermentation control, the pH of the fermentation broth is maintained within a certain range. For example, in one embodiment, the pH is maintained between about 4 and about 6.9, between about 5 and about 6.5, between about 5.1 and about 6, between about 5.2 and about 6, between about 4.5 and about 5, between about 4 and about 4.5, between about 4.75 and about 4.9, between about 4.6 and about 4.75, between about 4.45 and about 4.6, between about 4.3 and about 4.45, between about 4.6 and about 4.9, between about 4.45 and about 4.75, and between about 4.3 and about 4.6. [Example]

[0025] Example 1 :Control calculation Fermentations were performed using Clostridium ljungdahlii C-01 (ATCC 55988). Acid was measured in the permeate stream using NIR. The table below shows the control calculations over several replicates. As shown in the table, the controller increased the gas flow rate precisely when the acid concentration increased. Alternatively, the controller decreased the gas flow rate precisely when the acid concentration decreased. Error value = A M -A T Proportional term=P_const * E_val Error integral = IF(mode = "Cas", (previous E_int) + E_val * dt, (LN(previous GFR) / exp_const-P_term) * I_const) Integral term = E_int / I_const PID output=P_term+I_term Gas flow rate = IF(mode = "Cas", EXP(exp_const * PID_out), previous GFR) Acid target value (A T )=2.5g / L

[0026] [Table 2] TIFF0007825557000003.tif24962

[0027] dt=60, P_const=5, I_cont=1036, exp_const=0.062146 While the disclosure disclosed herein has been described with reference to specific embodiments, examples and applications thereof, numerous modifications and variations can be made thereto by those skilled in the art without departing from the scope of the disclosure as set forth in the claims.

Claims

1. 1. An automated fermentation process comprising: feeding a gaseous substrate comprising CO to a bioreactor at a substrate addition rate; providing acetogenic bacteria to the bioreactor; fermenting the gaseous substrate in a fermentation broth; separating the fermentation broth to provide a cell-free permeate stream; A in permeable flow M determining the concentration of A M is the concentration of carboxylic acids and carboxylates, A M using the control algorithm to adjust the rate of addition of the gaseous substrate; and maintaining the pH in the fermentation broth at 4.5 to 5. The process comprising:

2. The control algorithm is represented by Equation I term = E int / I by I term determining where I is a constant, In the formula, E int = (previous E int ) + (A M -A T ) * dt, wherein A T is the target concentration of carboxylic acids and carboxylates, and dt is the concentration of A in the permeate stream. M is the time interval between determining the previous E int and E int 2. The process of claim 1, wherein t is a value at the beginning and end, or a value at the time interval dt.

3. The control algorithm is expressed as the formula P term = (A M -A T ) * P by P term determining In the formula, A T 3. The process of claim 2, wherein π is the target concentration of carboxylic acids and carboxylates and P is a constant.

4. The control algorithm is Formula E int = (previous E int ) + (A M -A T ) * dt by E int where dt is the A in the permeate stream. M is the time interval between determining the previous E int and E int is a value at the start and end, or a value at a time interval dt; Formula I term = E int / I by I term wherein I is a constant; and Expression Controller output =P term +I term By controller output (In the formula, P term (A M -A T ) * P and A M and A T is as defined above and P is a constant. The process of claim 2 further comprising:

5. 3. The process of claim 2, wherein I is from 100 to 10,000.

6. 4. The process of claim 3, wherein P is 0 to 50.

7. 10. The process of claim 1, wherein the concentration of carboxylic acid is measured by an analytical technique selected from the group consisting of near-infrared spectroscopy (NIR), gas chromatography, high pressure liquid chromatography, mass spectrometry, and combinations thereof.

8. 10. The process of claim 1, wherein the process provides a productivity of at least 100 g ethanol / (L-day).

9. A in permeable flow M determining the concentration of A M 10. The process of claim 1, wherein the step of adjusting the rate of addition of the gaseous substrate using a control algorithm is completed within 30 minutes.

10. Acetogenic bacteria include Clostridium genus bacteria, Clostridium aceticum, Clostridium acetobutylicum, Clostridium acetobutylicum P262, Clostridium autoethanogenum, Clostridium carboxydivorans P7, Clostridium koskatii, Clostridium drakei, Clostridium ljungdahlii PETC, Clostridium ljungdahlii ERI2, Clostridium ljungdahlii C-01, Clostridium ljungdahlii O-52, Clostridium magnum, Clostridium pasteurianum, Clostridium ragsdali P11, Clostridium scatogenes, Clostridium thermoaceticum, Clostridium wurtunenense, Acetobacterium genus bacteria, Acetogenium kibui, Acetobacterium koskatii, Clostridium drakei, Clostridium ljungdahlii PTC, Clostridium ljungdahlii ERI2, Clostridium ljungdahlii C-01, Clostridium ljungdahlii O-52, Clostridium magnum, Clostridium pasteurianum, Clostridium ragsdali P11, Clostridium scatogenes, Clostridium thermoaceticum, Clostridium wurtunenense, Acetobacterium genus bacteria, Acetogenium kibui, Acetobacterium koskatii, Clostrid ...

2. The process of claim 1, wherein the bacterial strain is selected from the group consisting of Butyrobacterium notelae, Alkalibaculum bacilli CP11, Blautia producta, Butyrivacterium methylotrophicum, Cardanaerobacter subterraneanus, Cardanaerobacter subterraneanus pacificum, Carboxythermus hydrogenoformans, Desulfotomaculum kuznetsovii, Eubacterium limosum, Geobacter sulfreducens, Methanosarcina acetivorans, Methanosarcina barkeri, Moorella thermoacetica, Moorella thermoautotrophica, Oxobacter phenidii, Peptostreptococcus productus, Ruminococcus productus, Thermoanerobacter kibui, Clostridium sticklandii, and combinations thereof.

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