Abstract:
The present invention provides an apparatus and method for the production of hydrogen based on the capture of metabolic by-products of hydrogen-producing microbacteria, in which a bioreactor is maintained in an environment conducive to the growth of hydrogen-producing microbacteria and the production of hydrogen and at the same time is restrictive to the growth of undesirable microorganisms such as methanogens and the production of methane. The present invention utilizes concentrated growth of hydrogen-producing microbacteria such as  Klebsiella oxytoca . The invention provides a simple and cost-effective way to produce hydrogen by selectively harnessing hydrogen-producing microbacteria utilizing glucose-based solutions while substantially eliminating methane-producing microbacteria.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Patent Application No. 60/764,292, filed Feb. 1, 2006, which is incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to a method and apparatus for concentrated production of hydrogen-generating microbacteria cultures. More particularly, this invention relates to a method and apparatus for the biological production of hydrogen while substantially avoiding the production of methane, the invention utilizing concentrated growth of hydrogen-producing microbacteria such as  Klebsiella oxytoca . The invention provides a simple and cost-effective way to produce hydrogen by selectively harnessing hydrogen-producing microbacteria utilizing glucose-based solutions while substantially eliminating methane-producing microbacteria. 
       BACKGROUND OF THE INVENTION 
       [0003]    The production of hydrogen is an increasingly common and important procedure in the world today. Production of hydrogen in the United States alone currently amounts to about 3 billion cubic feet per year, with output likely to increase. Uses for the produced hydrogen are varied, ranging from uses in welding, in production of hydrochloric acid, and for reduction of metallic ores. An increasingly important use of hydrogen is in fuel cells or for combustion. This is directly related to the production of alternative fuels for machinery such as motor vehicles. Successful use of hydrogen as an alternative fuel can provide substantial benefits to the world at large. This is possible not only because hydrogen is produced without dependence on the location of specific oils or other ground resources, but because burning hydrogen is atmospherically clean. Essentially, no carbon dioxide or greenhouse gasses are produced when burning hydrogen. Thus, production of hydrogen as a fuel source can have a great impact on decreasing the use of fuels that produce greenhouse gases. 
         [0004]    Production of hydrogen from various methods generally is known. For example, electrolysis, which basically involves the use of electricity to decompose water into hydrogen and oxygen, is a commonly used process. Significant energy, however, is required to produce the needed electricity to perform the process. Similarly, steam reforming is another expensive method requiring fossil fuels as an energy source. As can be readily understood, the environmental benefits of producing hydrogen are at least partially offset when using a process that requires pollution-causing fuels as an energy source for the production of hydrogen. 
         [0005]    Thus, production of hydrogen from biological systems, wherein the energy for the process is substantially provided by naturally occurring bacteria, is an optimal solution. Fermentation of organic matter by hydrogen-producing microbacteria, such as  Bacillus  or  Clostridium , is one such method. However, substantial and useful production of hydrogen gas from microbacteria is problematic. The primary obstacle to sustained production of useful quantities of hydrogen by microbacteria has been the eventual stoppage of hydrogen production generally coinciding with the appearance of methane. This occurs when methanogenic bacteria invade the reactor environment, converting hydrogen to methane. This process occurs naturally in anaerobic environments such as marshes, swamp and pond sediments. As the appearance of methanogens in a biological system previously has been largely inevitable, continuous production of hydrogen from hydrogen-producing microbacteria has been unsuccessful in the past. 
         [0006]    New methods of hydrogen generation that optimize yields of hydrogen while minimizing expenditures, therefore, are needed. One possible method is to produce hydrogen in a biological system by converting organic matter into hydrogen gas. The production of biogas that is substantially hydrogen theoretically can be achieved in a bioreactor, in which hydrogen-producing microbacteria and an organic source solution are held in an environment favorable to hydrogen production. 
         [0007]    Microbiologists have known for many years that certain microorganisms produce hydrogen as a metabolic by-product. Two reviews of this body of knowledge are Kosaric and Lyng (1988) and Nandi and Sengupta (1998). Among the various organisms mentioned, the heterotrophic facultative anaerobes are of interest in this study, particularly those in the group known as enteric bacteria. Within this group are the mixed-acid fermentors, whose most well known member is  Escherichia coli . While fermenting glucose, these bacteria split the glucose molecule, forming two moles of pyruvate, an acetyl group is stripped from each pyruvate fragment leaving formic acid, which then is cleaved into equal amounts of carbon dioxide and hydrogen. Thus, during this process, one mole of glucose produces two moles of hydrogen gas. Also produced during this process are acetic and lactic acids, and minor amounts of succinic acid and ethanol. Other enteric bacteria (the 2, 3 butanediol fermentors) use a different enzyme pathway which causes additional CO 2  generation resulting in a 6:1 ratio of carbon dioxide to hydrogen production (Madigan et al., 1997). 
         [0008]    There are many sources of waste organic matter which could serve as a substrate for this microbial process, namely as a provider of pyruvate. One such attractive material would be organic-rich industrial wastewaters, particularly sugar-rich waters, such as fruit and vegetable processing wastes. Other sources include agricultural residues and other organic wastes such as sewage and animal manures. 
         [0009]    It is of further importance to increase the number of hydrogen-producing microorganisms in a system to the point that a fixed colony is existent. Increasing the number of hydrogen-producing microbacteria and thereby increasing the overall percentage of hydrogen-producing microbacteria is beneficial, particularly in large scale reactors. Therefore, it is important to create a bioreactor environment that is conducive to hydrogen-producing microbacterial growth and maintenance in addition to hydrogen production. 
         [0010]    Thus, there exists a need to produce substantial and useful levels of hydrogen in an inexpensive, environmentally friendly manner utilizing hydrogen-producing microbacteria. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention fulfills this need by providing an apparatus and method for the production of hydrogen based on the capture of metabolic by-products of hydrogen-producing microbacteria, in which a bioreactor is maintained in an environment conducive to the growth of hydrogen-producing microbacteria and the production of hydrogen and at the same time is restrictive to the growth of undesirable microorganisms such as methanogens and the production of methane. 
         [0012]    It is an object of the present invention to provide an apparatus and method for producing hydrogen from hydrogen-producing microbacteria that metabolize organic feed material which includes a bioreactor for receiving organic feed material and adapted to produce hydrogen from the hydrogen-producing microbacteria metabolizing the organic feed material, and a pH controller in operable relation to the bioreactor, wherein the pH controller can adjust the pH of the organic feed material in the system, wherein the pH controller is set to control the pH of the organic feed material to a range of about 3.5-6.0. 
         [0013]    It is a further object of the present invention to provide an apparatus and method for producing hydrogen from hydrogen-producing microbacteria that metabolize organic feed material which includes a bioreactor for receiving organic feed material and adapted to produce hydrogen from the hydrogen-producing microbacteria metabolizing the organic feed material, a heater for heating the organic feed material prior to introduction into the bioreactor, and a pH controller in operable relation to the bioreactor, wherein the pH controller can adjust the pH of the organic feed material in the system. 
         [0014]    It is a further object of the present invention to provide an apparatus and method wherein the heater heats the organic feed material to a temperature of about 60° C. to 100° C. 
         [0015]    These and other objects of the present invention will become more readily apparent from the following detailed description and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a plan view of the hydrogen production apparatus. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0017]    As used herein, the term “microbacteria” include bacteria and substantially microscopic cellular organisms. 
         [0018]    As used herein, the term “hydrogen-producing microbacteria” includes microorganisms that metabolize an organic substrate in one or a series of reactions that ultimately forms hydrogen as one of the end products. 
         [0019]    As used herein, the term “methanogens” refers to microbacteria that metabolize hydrogen in one or a series of reactions that produces methane as one of the end products. 
         [0020]    A hydrogen-producing bioreactor  10  for sustained production of hydrogen in accordance with the present invention is shown in  FIG. 1 . The bioreactor  10  is anaerobic and therefore substantially airtight. The bioreactor  10  may contain several openings. However, these openings are covered with substantially airtight coverings or connections, thereby keeping the environment in the bioreactor  10  substantially anaerobic. The bioreactor  10  can be any receptacle known in the art for carrying an aqueous solution  12 . Generally, the receptacle will be a limiting factor in the amount of hydrogen that can be produced. The larger the receptacle, the more aqueous solution containing hydrogen-producing bacteria, and, by extension, hydrogen, can be produced. Therefore, the size and shape of the bioreactor can vary widely within the spirit of the invention depending on the output of hydrogen desired and location limitations. In the present embodiment depicted in  FIG. 1 , the bioreactor  10  holds a volume of about 2 liters of aqueous solution. The embodiment of the invention, however, can be readily scaled to a much larger volume. 
         [0021]    The bioreactor  10  can be formed of any material suitable for holding an aqueous solution and that can create an airtight, anaerobic environment. In the present invention, the bioreactor  10  is constructed of acrylic materials. Other suitable materials include, for example and without limitation, metals and other plastics. Furthermore, the bioreactor  10  preferably is formed to substantially prevent the entry of air therein. 
         [0022]    To maintain the aqueous solution volume level at a general constant level, the bioreactor  10  preferably provides means to remove excess solution. In the present embodiment, the bioreactor  10  includes an effluent tube  48  that extends from inside the bioreactor  10  to outside the bioreactor  10  and into a suitable location for effluent, such as a sewer. Inside the bioreactor  10 , the effluent tube  48  extends upwards to a surface level  16  that generally coincides to a level that is a preferred top surface area of the solution if the bioreactor  10  is filled. The effluent tube  48  has an open end  14  at or near the surface level  16 . When the bioreactor  10  is filled, the open end of the effluent tube  48  allows a gravity overflow to maintain a constant fluid volume. The bioreactor  10  may further contain a retaining plate  26  and perforated acrylic plate  28 . 
         [0023]    The bioreactor  10  contains one or a multiplicity of substrates  18  for providing surface area for attachment and growth of bacterial biofilms. The sizes and shapes of the substrates  18  can vary widely, including, but not limited to, flat surfaces, pipes, rods, beads, slats, tubes, slides, screens, honeycombs, spheres, objects with latticework, or other objects with holes bored through the surface. 
         [0024]    Substrates  18  preferably are substantially free of small interior spaces that potentially fill with gas. In the present embodiment, the bioreactor  10  contains substrates  18  comprising about 150 pieces of floatable one inch plastic media to provide surface area for attachment of the bacterial biofilm. This includes, but is not limited to, Flexiring™ Random Packing (Koch-Glitsch.) The packing may be retained below the liquid surface by the perforated acrylic plate  28 . 
         [0025]    In an embodiment of the present invention, organic feed solution  36  first is contained in a reservoir  56 . The reservoir  56  is a container known in the art that can contain an organic feed solution. The size, shape and material of the reservoir  56  can vary widely within the spirit of the invention. In one embodiment, the reservoir  56  is one or a multiplicity of storage tanks that are adaptable to receive, hold and store the organic feed solution  36  when not in use, wherein the one or a multiplicity of storage tanks may be mobile. In another embodiment, the reservoir  56  is a wastewater well that is adaptable to receive and contain wastewater and/or effluent from an industrial process. In a further embodiment, the reservoir  56  is adaptable to receive and contain wastewater which is effluent from a juice manufacturing industrial process, such that the effluent held in the reservoir  56  is a sugar rich juice sludge. 
         [0026]    The organic feed solution  36  in the reservoir  56  is conveyed throughout the apparatus, such that the apparatus is a closed system of continuous movement. Conveyance of organic feed solution  36  can be achieved by any conveying means known in the art, for example, one or a multiplicity of pumps. The apparatus of the present invention uses a closed system, such that a few well placed conveying means can convey the organic feed solution  36  throughout the apparatus, from the reservoir  56  to an optional equalization tank  54  to the heating device  20  to the bioreactor  10  to outside of the bioreactor  10 . In an embodiment, the organic feed solution  36  contained in the reservoir  56  is conveyed into the optional equalization tank  54  with a pump  58 . The pump  58  is in operable relation to the reservoir  56  such that it aids removal movement of organic feed solution  36  to the equalization tank  54  at a desired, adjustable flow rate, wherein the pump  58  can be any pump known in the art suitable for pumping liquids. In a preferred embodiment, the pump  58  is a submersible sump pump. 
         [0027]    The organic feed solution  36  leaving the reservoir  56  can be conveyed either into the equalization tank  54  or the heating device  20 . The equalization tank  54  is an optional intermediary container for holding the organic feed solution  36  between the reservoir  56  and the heating device  20 . The equalization tank  54  provides an intermediary container that can help control the flow rates of organic feed solution  36  into the heating device  20  by providing a slower flow rate out of the equalization tank  54  than the flow rate of organic feed solution into the equalization tank  54 . An equalization tank is most useful when the reservoir  56  receives effluent from an industrial facility such that it is difficult to control flow into the reservoir  56 . The equalization tank can be formed of any material suitable for holding and treating the organic feed solution  36 . In the present invention, the equalization tank  54  is constructed of acrylic materials. Other materials include, but are not limited to, metals or non-acrylic plastics. Additionally, the size and shape of the equalization tank  54  can vary widely within the spirit of the invention depending on output desired and location limitations. 
         [0028]    The organic feed solution is heated prior to conveyance into the bioreactor to deactivate or kill methane producing microorganisms, i.e., methanogens. The heating can occur anywhere upstream. In one embodiment, the heating is achieved in the heating device  20 , wherein the organic feed solution  36  is heated within the heating device. Alternatively, organic feed solution can be heated at additional or alternate locations in the hydrogen production system. 
         [0029]    In a preferred embodiment, the feed source  36  is a grape juice solution prepared using Welch&#39;s Concord Grape Juice™ diluted in tap water at approximately 32 ml of juice per liter. The grape juice solution is inoculated with one or a multiplicity of hydrogen-producing bacteria in an inoculation step. The added hydrogen-producing microbacteria may include the same types of microbacteria that occur naturally in organic-rich industrial wastewaters. In an embodiment, the hydrogen-producing microbacteria added in an inoculation step are microbacteria that thrive in pH levels of about 3.5 to 6.0 and can survive at elevated temperatures. These hydrogen-producing microbacteria include, but are not limited to,  Clostridium sporogenes, Bacillus licheniformis  and  Kleibsiella oxytoca . The grape juice solution is aerated for 24 hours to substantially remove any chlorine. Due to the acidity of the juice, the pH of the feed solution typically is about 4.0. The constitutional make-up of the grape juice solution is shown in Table 1. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
             
               
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Composition of concord grape juice. Source: 
               
               
                 Welch&#39;s Company, personal comm., 2005. 
               
             
          
           
               
                   
                 Concentration (unit indicated) 
                   
               
             
          
           
               
                   
                 Constituent 
                 Mean 
                 Range 
               
               
                   
                   
               
               
                   
                 Carbohydrates 1   
                   
                 15–18% 
               
               
                   
                 glucose 
                 6.2% 
                 5–8% 
               
               
                   
                 fructose 
                 5.5% 
                 5–8% 
               
               
                   
                 sucrose 
                 1.8% 
                 0.2–2.3% 
               
               
                   
                 maltose 
                 1.9% 
                   0–2.2% 
               
               
                   
                 sorbitol 
                 0.1% 
                   0–0.2% 
               
               
                   
                 Organic Acids 1   
                   
                 0.5–1.7% 
               
               
                   
                 Tartaric acid 
                 0.84%  
                  0.4–1.35% 
               
               
                   
                 Malic acid 
                 0.86%  
                 0.17–1.54% 
               
               
                   
                 Citric acid 
                 0.044%  
                 0.03–0.12% 
               
               
                   
                 Minerals 1   
               
             
          
           
               
                   
                 Calcium 
                 17–34 
                 mg/L 
               
               
                   
                 Iron 
                 0.4–0.8 
                 mg/L 
               
               
                   
                 Magnesium 
                 6.3–11.2 
                 mg/L 
               
               
                   
                 Phosphorous 
                 21–28 
                 mg/L 
               
               
                   
                 Potassium 
                 175–260 
                 mg/L 
               
               
                   
                 Sodium 
                 1–5 
                 mg/L 
               
               
                   
                 Copper 
                 0.10–0.15 
                 mg/L 
               
               
                   
                 Manganese 
                 0.04–0.12 
                 mg/L 
               
               
                   
                 Vitamins 1   
               
               
                   
                 Vitamin C 
                 4 
                 mg/L 
               
               
                   
                 Thiamine 
                 0.06 
                 mg/L 
               
               
                   
                 Riboflavin 
                 0.04 
                 mg/L 
               
               
                   
                 Niacin 
                 0.2 
                 mg/L 
               
               
                   
                 Vitamin A 
                 80 
                 I.U. 
               
             
          
           
               
                   
                 pH 
                 3.0–3.5    
               
               
                   
                 Total solids 
                 18.5% 
               
               
                   
                   
               
               
                   
                   1 additional trace constituents in these categories may be present. 
               
             
          
         
       
     
         [0030]    In a preferred embodiment, the organic feed solution  36  is heated in the heating device  20  and conveyed into the bioreactor  10  with a feed pump  22  at a desired flow rate through a conveying means  44  and inlet  46 . The heating unit  20  can elevate the temperature of the solution in the bioreactor  10  between a range of about 60° C. to about 100° C. A heating temperature of about 60° C.-70° C. for at least 30 minutes temporarily deactivates methanogens in a pasteurization-like process. Heating temperatures of between about 90° C.-100° C. for at least thirty minutes can destroy methanogens. In contrast, many hydrogen-producing microbacteria are resistant to temperatures up to about 110° C. for over three hours. The heating device  20  enables heating of the organic feed solution  36  to a temperature of about 60° C.-110° C. to substantially deactive or kill the methanogens while leaving any hydrogen-producing microbacteria substantially functional. In a preferred embodiment, the temperature of the feed source  36  is elevated in the heating unit  20  to about 65° C. 
         [0031]    The heating device  20  can be any suitable receptacle known in the art for holding, receiving and conveying the feed source  36 . Preferably, the heating device  20  is formed substantially from metals, acrylics, other plastics or combinations thereof, yet the material can vary widely within the spirit of the invention to include other suitable materials. Similarly, the size and shape of the heating device  20  can vary widely within the spirit of the invention depending on the output required and location limitations. In preferred embodiments, retention time in the heating device  20  is at least one hour. Retention time marks the average time that any particular part of the feed source  36  is retained in the heating device  20 . 
         [0032]    To maintain the temperatures at desired levels, at least one temperature sensor  52  monitors a temperature indicative of the feed source  36  temperature, preferably the temperature level of the heating device  20 . In preferred embodiments, an electronic controller is provided having at least one microprocessor adapted to process signals from one or a plurality of devices providing feed source  36  parameter information, wherein the electronic controller is operably related to at least one actuatable terminal and is arranged to control the operation of and to controllably heat the heating device  20  and/or any contents therein. The electronic controller is located or coupled to the heating device  20 , or can alternatively be at a third or remote location. In alternate embodiments, the controller for controlling the temperature of the heating device  20  is not operably related to the temperature sensor  52 , and temperatures can be adjusted manually in response to temperature readings taken from the temperature sensor  52 . 
         [0033]    The feed pump  22  pumps the feed source  36  through the conveying means  44 , through the inlet  46  and into the bioreactor  10 . The inlet  46  generally can be located at any location along the bioreactor  10 . However, in preferred embodiments, the inlet  46  is located near the upper portion of the bioreactor  10  below the surface level  16  and above the retaining plate  26 . The conveying means can be any apparatus known in the art, most typically a tube. Once inside the bioreactor  10 , the feed source  36  becomes solution. 
         [0034]    The bioreactor  10  preferably is equipped with a recycle pump  24  to rapidly recirculate solution drawn at or near the top of the bioreactor  10  to the lower levels of the bioreactor  10 . In one embodiment, the recycle pump  24  takes solution from above a retaining plate  26  and reintroduces the solution through a deflector fitting  30  into the bottom of the reactor, resulting in a dispersed vertical flow of liquid. The up-flow circulation aids microbacteria within the solution to find glucose sources on which to grow biofilms. 
         [0035]    The pH level of the solution is controlled within the bioreactor  10 . Precise control of a pH level provides an environment that enables at least some hydrogen-producing bacteria to function while similarly providing an environment unfavorable to methanogens. This enables the concept of allowing microbacterial reactions to create hydrogen without subsequently being overrun by methanogens that convert the hydrogen to methane. This produces a biological system in the bioreactor  10  without substantial methane production. 
         [0036]    Control of pH of the solution in the bioreactor can be achieved by any means known in the art. In the present embodiments, a pH control monitoring device  32  monitors the pH and can add a pH control solution in an automated manner if the pH of the solution in the bioreactor moves out of a desired range. In a preferred embodiment, the pH monitor controls the bioreactor solution&#39;s pH through automated addition of a 0.2 M NaOH solution  34 . One such apparatus for achieving this is an Etatron DLX pH monitoring device. Preferred ranges of pH for the bioreactor solution is between about 3.5 and 6.5, with a more preferred range between about 4.0 and 5.5. 
         [0037]    The bioreactor  10  preferably further includes an oxidation-reduction potential (ORP) probe  38  which allows the monitoring of redox potential of the solution, an overflow cut-off switch  40  to turn off the feed pump  22  if the solution exceeds a certain level in the bioreactor and a device for capturing the hydrogen. In the present embodiment, the hydrogen is conveyed from the bioreactor  10  through a passage  42  and captured in bags  50  made of materials specifically designed to contain hydrogen (SKC, Inc.). After capture, the hydrogen gas may be further treated, cleaned and/or stored. 
         [0038]    The organic feed solution preferably is carbohydrate-rich to better enable the hydrogen production reaction. There are many organic sources which can be utilized as a feed source. These include, for example, agricultural residues, industrial wastes and other organic material such as sewage or manure. Examples of organic source material include, without limitation, organic-rich industrial wastewaters such as fruit and vegetable processing wastes or juices. In a preferred embodiment, the solution introduced into the receptacle is a high sugar organic waste, for example and without limitation, sludge or other waste or by-products that are resultant from the production of a fruit juice, such as grape juice. In additional embodiments, wastewaters rich not only in sugars but also in protein and fats can be used, such as milk product wastes. The most complex potential source of energy for this process would include sewage-related wastes, such as municipal sewage and animal manures. Typical hydrogen-producing microbacteria are adept at metabolizing the high sugar organic waste into bacterial waste products 
         [0039]    Hydrogen-producing microbacteria metabolize the sugars in the organic feed solution under the reactions: 
         [0000]      Glucose→2 Pyruvate  (1) 
         [0000]      2 Pyruvate+2 Coenzyme A→2 Acetyl-CoA+2 HCOOH  (2) 
         [0000]      2 HCOOH→2H 2 +2 CO 2   (3) 
         [0040]    During this process, one mole of glucose produces two moles of hydrogen gas and carbon dioxide. In alternate embodiments, other organic feed solutions include agricultural residues and other organic wastes such as sewage and manures. Typical hydrogen-producing microbacteria are adept at metabolizing the high sugar organic waste into bacterial waste products. The wastewater may be further treated by aeration, diluting the solution with water or other dilutants, adding compounds that control the pH of the solution or other treatment steps. For example, the electrolyte contents (Na, K, Cl, Mg, Ca, etc.) of the organic feed solution can be adjusted. Further, the solution may be supplemented with phosphorus (NaH 2 PO 4 ) or yeast extract. 
         [0041]    The organic feed solution of the present invention provides a plentiful feeding ground for hydrogen-producing microbacteria which is naturally infested with these microorganisms. While hydrogen-producing microbacteria typically occur naturally in an organic feed solution, the organic feed solution of the present invention preferably is further inoculated with hydrogen-producing microbacteria in an inoculation step. In further preferred embodiments, the inoculation is an initial, one-time addition to the bioreactor at the beginning of the hydrogen production process. The initial inoculation provides enough hydrogen-producing microbacteria to produce sustained colonies of hydrogen-producing microbacteria within the bioreactor. The sustained colonies allow the sustained production of hydrogen. Further inoculations of hydrogen-producing microbacteria may be added as desired. The added hydrogen-producing microbacteria may include the same types of microorganisms that occur naturally in the organic feed solution. In preferred embodiments, the hydrogen-producing microbacteria, whether occurring naturally or added in an inoculation step, are preferably microorganisms that thrive in pH levels of about 3.5 to 6.0 and can survive in temperatures of 60° F.-110° F. or, more preferably, 60° F.-75°. These hydrogen-producing microbacteria include, but are not limited to,  Clostridium sporogenes, Bacillus licheniformis  and  Kleibsiella oxytoca . Hydrogen-producing microbacteria can be obtained from a microorganism culture laboratory or like source. Other hydrogen-producing microbacteria or hydrogen-producing microbacteria known in the art, however, can be used within the spirit of the invention. The inoculation step can occur in the bioreactor or elsewhere in the apparatus. 
         [0042]    Although hydrogen-producing microbacteria typically occur naturally in the organic feed solution, the solution in the bioreactor may be inoculated further with one or a multiplicity of hydrogen-producing bacteria in an inoculation step. The inoculation may be an initial, one-time addition to the bioreactor at the beginning of the hydrogen production process. Further inoculations, however, may be added as desired. The added hydrogen-producing microbacteria may include the same types of microbacteria that occur naturally in the feed source. In preferred embodiments, the hydrogen-producing microbacteria, whether occurring naturally or added in an inoculation step, are microbacteria that thrive in pH levels of about 3.5 to 6.0 and can survive at elevated temperatures. These hydrogen-producing microbacteria include, but are not limited to,  Clostridium sporogenes, Bacillus licheniformis  and  Kleibsiella oxytoca . Hydrogen-producing microbacteria can be obtained from a bacterial culture laboratory or like source. 
         [0043]    In an embodiment, the preferred hydrogen-producing bacteria are  Kleibsiella oxytoca , a facultative enteric bacterium capable of hydrogen generation.  Kleibsiella oxytoca  may be obtained from a source such as yeast extract. In this embodiment, the continuous input of seed organisms from the yeast extract in the feed source results in a culture of  Kleibsiella oxytoca  in the bioreactor solution. Alternatively, the bioreactor may be directly inoculated with  Kleibsiella oxytoca . In this embodiment, the inoculum for each bioreactor is about 100 ml (of a 48 hour culture in nutrient broth) added to 1.9 L of diluted grape juice, with each bioreactor operating in batch mode for one day. The bioreactors need not be stripped of oxygen before or after inoculation. The ORP is monitored with the ORP sensor  38 . Once ORP drops below about −200 mV, gas production commences. Subsequently, when operating in a continuous flow mode, the ORP typically is in the range of about −300 to −450 mV. 
         [0044]    The volume of collected gas can be determined by water displacement before and after scrubbing with concentrated NaOH. Samples of scrubbed and dried gas may be analyzed for hydrogen and methane by gas chromatography with a thermal conductivity detector (TCD) and/or with a flame ionization detector (FID). Both hydrogen and methane produce a response in the TCD, but the response to methane is improved in the FID (hydrogen is not detected by an FID, which uses hydrogen as a fuel for the flame). Pure hydrogen gas is can be obtained from a tank of ultra high purity hydrogen and methane can be obtained from a laboratory gas cock. 
         [0045]    The present invention also provides a method for producing hydrogen from organic solutions comprised of providing an organic feed source solution, heating the organic feed source solution with a heating device, conveying the organic feed source solution into a bioreactor, inoculating the organic feed source solution with one or a multiplicity of hydrogen-producing microbacteria to produce a microbacteria solution, monitoring the microbacteria solution with a pH monitoring device which is capable of introducing a compound, such as, for example and without limitation, NaOH, into the microbacteria solution if the pH of the microbacteria solution moves out of a desired range, creating an upstream movement of the microbacteria solution in the bioreactor and capturing the hydrogen produced in a suitable device typically known in the art. 
         [0046]    The present invention is more particularly described in the following non-limiting example, which is intended to be illustrative only, as numerous modifications and variations therein will be apparent to those skilled in the art. 
       EXAMPLE 1 
       [0047]    A multiplicity of bioreactors initially were operated at pH 4.0 and a flow rate of 2.5 mL min −1 , resulting in a hydraulic retention time (HRT) of about 13 h (0.55 d). This is equivalent to a dilution rate of 1.8 d −1 . After one week, all six bioreactors were at pH 4.0, the ORP ranged from −300 to −450 mV, total gas production averaged 1.6 L d −1  and hydrogen production averaged 0.8 L d −1 . The mean chemical oxygen demand (COD) of the organic feed material during this period was 4,000 mg L −1  and the mean effluent COD was 2,800 mg L −1 , for a reduction of 30%. After one week, the pHs of certain bioreactors were increased by one half unit per day until the six bioreactors were established at different pH levels ranging from 4.0 to 6.5. Over the next three weeks at the new pH settings, samples were collected and analyzed each weekday. It was found that the optimum for gas production in this embodiment was pH 5.0 at 1.48 L hydrogen d −1 ) (Table 2). This was equivalent to about 0.75 volumetric units of hydrogen per unit of bioreactor volume per day. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Production of hydrogen in 2-L anaerobic bioreactors as a function 
               
               
                 of pH. 
               
             
          
           
               
                   
                 Total 
                   
                 H2 
                 H2 per 
               
               
                   
                 gas 
                 H2 
                 L/g 
                 Sugar 
               
               
                 pH 
                 L/day 
                 L/day 
                 COD 
                 moles/mole 
               
               
                   
               
             
          
           
               
                 4.0 a   
                 1.61 
                 0.82 
                 0.23 
                 1.81 
               
               
                 4.5 b   
                 2.58 
                 1.34 
                 0.23 
                 1.81 
               
               
                 5.0 c   
                 2.74 
                 1.48 
                 0.26 
                 2.05 
               
               
                 5.5 d   
                 1.66 
                 0.92 
                 0.24 
                 1.89 
               
               
                 6.0 d   
                 2.23 
                 1.43 
                 0.19 
                 1.50 
               
               
                 6.5 e   
                 0.52 
                 0.31 
                 0.04 
                 0.32 
               
               
                   
               
               
                   a mean of 20 data points 
               
               
                   b mean of 14 data points 
               
               
                   c mean of 11 data points 
               
               
                   d mean of 7 data points 
               
               
                   e mean of 6 data points 
               
             
          
         
       
     
         [0048]    Also shown in Table 2 is the hydrogen production rate per g of COD, which also peaked at pH 5.0 at a value of 0.26 L g −1  COD consumed. To determine the molar production rate, it was assumed that each liter of hydrogen gas contained 0.041 moles, based on the ideal gas law and a temperature of 25° C. Because most of the nutrient value in the grape juice was simple sugars, predominantly glucose and fructose (Table 1 above), it was assumed that the decrease in COD was due to the metabolism of glucose. Based on the theoretical oxygen demand of glucose (1 mole glucose to 6 moles oxygen), one gram of COD is equivalent to 0.9375 g of glucose. Therefore, using those conversions, the molar hydrogen production rate as a function of pH ranged from 0.32 to 2.05 moles of hydrogen per mole of glucose consumed. As described above, the pathway appropriate to these microorganisms results in two moles of hydrogen per mole of glucose, which was achieved at pH 5.0. The complete data set is provided in Tables 3a and 3b. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3a 
               
               
                   
               
               
                 Bioreactor Operating Data 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 GAS 
                   
               
             
          
           
               
                   
                 Tot 
                 after 
                 Liquid 
                   
               
             
          
           
               
                   
                 collection 
                 volume 
                 scrubbing 
                 Effluent 
                 NaOH 
                 Net Feed 
                 Readings 
               
             
          
           
               
                 Date 
                 Reactor 
                 hours 
                 (mL) 
                 (mL) 
                 (mL) 
                 (mL) 
                 (mL) 
                 ORP 
                 pH 
               
               
                   
               
               
                 17-Nov 
                 C 
                 5.5 
                 360 
                 200 
                 840 
                 120 
                 720 
                 −344 
                 4.9 
               
               
                 18-Nov 
                 C 
                 5 
                 370 
                 200 
                 1120 
                 70 
                 1050 
                 −328 
                 4.9 
               
               
                 29-Nov 
                 C 
                 4.25 
                 415 
                 200 
                 920 
                 50 
                 870 
                 −403 
                 4.9 
               
               
                 17-Nov 
                 E 
                 5.5 
                 490 
                 270 
                 1210 
                 115 
                 1095 
                 −352 
                 5.0 
               
               
                 1-Dec 
                 D 
                 3.5 
                 540 
                 250 
                 710 
                 85 
                 625 
                 −395 
                 5.0 
               
               
                 17-Nov 
                 F 
                 5.5 
                 475 
                 225 
                 1120 
                 130 
                 990 
                 −367 
                 5.0 
               
               
                 5-Dec 
                 D 
                 4.5 
                 580 
                 310 
                 710 
                 77 
                 633 
                 −423 
                 5.0 
               
               
                 6-Dec 
                 D 
                 3 
                 450 
                 240 
                 490 
                 43 
                 447 
                 −420 
                 5.0 
               
               
                 17-Nov 
                 D 
                 3.5 
                 680 
                 415 
                 580 
                 83 
                 497 
                 −326 
                 5.0 
               
               
                 2-Dec 
                 D 
                 3.75 
                 640 
                 340 
                 830 
                 66 
                 764 
                 −412 
                 5.0 
               
               
                 22-Nov 
                 C 
                 3.75 
                 460 
                 295 
                 800 
                 50 
                 750 
                 −349 
                 5.0 
               
               
                 averages 
                   
                 4.34 
                 496 
                 268 
                 848 
                 81 
                 767 
                 −374.5 
                 5.0 
               
               
                 5-Dec 
                 C 
                 4.5 
                 470 
                 250 
                 900 
                 103 
                 797 
                 −429 
                 5.4 
               
               
                 18-Nov 
                 F 
                 5 
                 90 
                 45 
                 600 
                 55 
                 545 
                 −451 
                 5.5 
               
               
                 21-Nov 
                 D 
                 4 
                 130 
                 70 
                 830 
                 80 
                 750 
                 −454 
                 5.5 
               
               
                 22-Nov 
                 D 
                 3.75 
                 360 
                 250 
                 765 
                 68 
                 696 
                 −461 
                 5.5 
               
               
                 29-Nov 
                 D 
                 4.25 
                 100 
                 50 
                 940 
                 100 
                 840 
                 −456 
                 5.5 
               
               
                 2-Dec 
                 C 
                 3.75 
                 550 
                 290 
                 810 
                 93 
                 717 
                 −430 
                 5.5 
               
               
                 6-Dec 
                 C 
                 3 
                 250 
                 130 
                 570 
                 45 
                 525 
                 −428 
                 5.5 
               
               
                 averages 
                   
                 4.04 
                 279 
                 155 
                 774 
                 78 
                 696 
                 −444.1 
                 5.5 
               
               
                 21-Nov 
                 E 
                 4 
                 350 
                 250 
                 930 
                 130 
                 800 
                 −400 
                 6.0 
               
               
                 22-Nov 
                 E 
                 3.75 
                 380 
                 280 
                 820 
                 127 
                 693 
                 −411 
                 6.0 
               
               
                 29-Nov 
                 E 
                 4.25 
                 360 
                 230 
                 870 
                 71 
                 799 
                 −467 
                 6.0 
               
               
                 1-Dec 
                 E 
                 3.5 
                 420 
                 250 
                 770 
                 127 
                 643 
                 −471 
                 6.0 
               
               
                 2-Dec 
                 E 
                 3.75 
                 280 
                 170 
                 540 
                 85 
                 455 
                 −443 
                 6.0 
               
               
                 5-Dec 
                 E 
                 4.5 
                 410 
                 240 
                 930 
                 156 
                 774 
                 −487 
                 6.0 
               
               
                 6-Dec 
                 E 
                 3 
                 280 
                 170 
                 660 
                 105 
                 555 
                 −490 
                 6.0 
               
               
                 averages 
                   
                 3.82 
                 354 
                 227 
                 789 
                 114 
                 674 
                 −453 
                 6.0 
               
               
                 29-Nov 
                 F 
                 4.25 
                 90 
                 45 
                 870 
                 150 
                 720 
                 −501 
                 6.5 
               
               
                 2-Dec 
                 F 
                 3.75 
                 20 
                 0 
                 810 
                 136 
                 674 
                 −497 
                 6.5 
               
               
                 22-Nov 
                 F 
                 3.75 
                 120 
                 105 
                 790 
                 128 
                 662 
                 −477 
                 6.5 
               
               
                 5-Dec 
                 F 
                 4.5 
                 10 
                 0 
                 670 
                 121 
                 549 
                 −532 
                 6.5 
               
               
                 6-Dec 
                 F 
                 3 
                 60 
                 50 
                 480 
                 90 
                 390 
                 −515 
                 6.5 
               
               
                 21-Nov 
                 F 
                 4 
                 200 
                 100 
                 910 
                 150 
                 760 
                 −472 
                 6.5 
               
               
                 averages 
                   
                 3.88 
                 83 
                 50 
                 755 
                 129 
                 626 
                 −499 
                 6.5 
               
               
                   
               
             
          
           
               
                   
                 COD 
                 Performance 
               
             
          
           
               
                   
                 Feed 
                 Effluent 
                 Removal 
                 Loading 
                 Consumed 
                 Total gas 
                 H2 
                 H2 
               
               
                 Date 
                 (mg/L) 
                 (mg/L) 
                 (mg/L) 
                 (g) 
                 (g) 
                 L/day 
                 L/day 
                 L/g COD 
               
               
                   
               
               
                 17-Nov 
                 4,907 
                 2,880 
                 2,027 
                 3.533 
                 1.459 
                 1.57 
                 0.87 
                 0.14 
               
               
                 18-Nov 
                 3,680 
                 2,480 
                 1,200 
                 3.864 
                 1.260 
                 1.78 
                 0.96 
                 0.16 
               
               
                 29-Nov 
                 5,013 
                 3,093 
                 1,920 
                 4.362 
                 1.670 
                 2.34 
                 1.13 
                 0.12 
               
               
                 17-Nov 
                 4,907 
                 4,747 
                 160 
                 5.373 
                 0.175 
                 2.14 
                 1.18 
                 1.54 
               
               
                 1-Dec 
                 6,173 
                 3,573 
                 1,600 
                 3.233 
                 1.000 
                 3.70 
                 1.71 
                 0.25 
               
               
                 17-Nov 
                 4,907 
                 3,760 
                 1,147 
                 4.858 
                 1.135 
                 2.07 
                 0.98 
                 0.20 
               
               
                 5-Dec 
                 4,267 
                 3,573 
                 694 
                 2.701 
                 0.439 
                 3.09 
                 1.65 
                 0.71 
               
               
                 6-Dec 
                 4,853 
                 3,253 
                 1,600 
                 2.169 
                 0.715 
                 3.60 
                 1.92 
                 0.34 
               
               
                 17-Nov 
                 4,907 
                 4,213 
                 694 
                 2.439 
                 0.345 
                 4.66 
                 2.85 
                 1.20 
               
               
                 2-Dec 
                 4,587 
                 3,787 
                 800 
                 3.504 
                 0.611 
                 4.10 
                 2.18 
                 0.56 
               
               
                 22-Nov 
                 4,107 
                 1,280 
                 2,827 
                 3.080 
                 2.120 
                 2.94 
                 1.89 
                 0.14 
               
               
                 averages 
                 4,664 
                 3,331 
                 1,333 
                 3.579 
                 1.023 
                 2.74 
                 1.48 
                 0.26 
               
               
                 5-Dec 
                 4,267 
                 3,413 
                 854 
                 3.401 
                 0.680 
                 2.51 
                 1.33 
                 0.37 
               
               
                 18-Nov 
                 3,680 
                 3,440 
                 240 
                 2.006 
                 0.131 
                 0.43 
                 0.22 
                 0.34 
               
               
                 21-Nov 
                 3,493 
                 3,360 
                 133 
                 2.620 
                 0.100 
                 0.78 
                 0.42 
                 0.70 
               
               
                 22-Nov 
                 4,107 
                 2,880 
                 1,227 
                 2.858 
                 0.854 
                 2.30 
                 1.60 
                 0.29 
               
               
                 29-Nov 
                 5,013 
                 3,307 
                 1,707 
                 4.211 
                 1.434 
                 0.56 
                 0.28 
                 0.03 
               
               
                 2-Dec 
                 4,587 
                 3,573 
                 1,014 
                 3.289 
                 0.727 
                 3.52 
                 1.86 
                 0.40 
               
               
                 6-Dec 
                 4,853 
                 3,627 
                 1,226 
                 2.548 
                 0.644 
                 2.00 
                 1.04 
                 0.20 
               
               
                 averages 
                 4,286 
                 3,371 
                 914 
                 2.982 
                 0.636 
                 1.66 
                 0.92 
                 0.24 
               
               
                 21-Nov 
                 3,493 
                 2,987 
                 506 
                 2.794 
                 0.406 
                 2.10 
                 1.50 
                 0.62 
               
               
                 22-Nov 
                 4,107 
                 2,453 
                 1,653 
                 2.846 
                 1.146 
                 2.43 
                 1.79 
                 0.24 
               
               
                 29-Nov 
                 5,013 
                 1,973 
                 3,040 
                 4.006 
                 2.429 
                 2.03 
                 1.30 
                 0.09 
               
               
                 1-Dec 
                 5,173 
                 2,933 
                 2,240 
                 3.326 
                 1.440 
                 2.88 
                 1.71 
                 0.17 
               
               
                 2-Dec 
                 4,587 
                 3,360 
                 1,227 
                 2.087 
                 0.558 
                 1.79 
                 1.09 
                 0.30 
               
               
                 5-Dec 
                 4,267 
                 3,253 
                 1,014 
                 3.303 
                 0.785 
                 2.19 
                 1.28 
                 0.31 
               
               
                 6-Dec 
                 4,853 
                 2,293 
                 2,560 
                 2.693 
                 1.421 
                 2.24 
                 1.36 
                 0.12 
               
               
                 averages 
                 4,499 
                 2,750 
                 1,749 
                 3.033 
                 1.179 
                 2.23 
                 1.43 
                 0.19 
               
               
                 29-Nov 
                 5,013 
                 1,707 
                 3,307 
                 3.610 
                 2.381 
                 0.51 
                 0.25 
                 0.02 
               
               
                 2-Dec 
                 4,587 
                 3,573 
                 1,014 
                 3.092 
                 0.683 
                 0.13 
                 0.00 
                 0.00 
               
               
                 22-Nov 
                 4,107 
                 2,240 
                 1,867 
                 2.719 
                 1.236 
                 0.77 
                 0.67 
                 0.08 
               
               
                 5-Dec 
                 4,267 
                 2,827 
                 1,440 
                 2.343 
                 0.791 
                 0.05 
                 0.00 
                 0.00 
               
               
                 6-Dec 
                 4,853 
                 2,240 
                 2,613 
                 1.893 
                 1.019 
                 0.48 
                 0.40 
                 0.05 
               
               
                 21-Nov 
                 3,493 
                 2,613 
                 880 
                 2.655 
                 0.669 
                 1.20 
                 0.60 
                 0.15 
               
               
                 averages 
                 4,387 
                 2,533 
                 1,853 
                 2.745 
                 1.160 
                 0.52 
                 0.31 
                 0.04 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3b 
               
               
                   
               
               
                 Bioreactor Operating Data Continued. 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Gas 
                   
               
             
          
           
               
                   
                 Total 
                 after 
                 Liquid 
                   
               
             
          
           
               
                   
                 collection 
                 volume 
                 scrubbing 
                 Effluent 
                 NaOH 
                 Net Feed 
                 Readings 
               
             
          
           
               
                 Date 
                 Reactor 
                 hours 
                 (mL) 
                 (mL) 
                 (mL) 
                 (mL) 
                 (mL) 
                 ORP 
                 pH 
               
               
                   
               
               
                 14-Nov 
                 A 
                 5 
                 540 
                 220 
                 780 
                 0 
                 780 
                 −408 
                 4.0 
               
               
                 14-Nov 
                 B 
                 5 
                 380 
                 220 
                 840 
                 0 
                 840 
                 −413 
                 4.1 
               
               
                 14-Nov 
                 C 
                 5 
                 350 
                 170 
                 870 
                 0 
                 870 
                 −318 
                 4.1 
               
               
                 14-Nov 
                 D 
                 5 
                 320 
                 130 
                 920 
                 0 
                 920 
                 −372 
                 4.1 
               
               
                 14-Nov 
                 E 
                 5 
                 240 
                 100 
                 920 
                 0 
                 920 
                 −324 
                 4.3 
               
               
                 14-Nov 
                 F 
                 5 
                 50 
                 25 
                 810 
                 0 
                 810 
                 −329 
                 4.0 
               
               
                 15-Nov 
                 A 
                 5.5 
                 450 
                 230 
                 1120 
                 25 
                 1095 
                 −400 
                 4.0 
               
               
                 15-Nov 
                 B 
                 5.5 
                 450 
                 235 
                 1180 
                 35 
                 1145 
                 −384 
                 4.0 
               
               
                 15-Nov 
                 C 
                 5.5 
                 250 
                 130 
                 640 
                 0 
                 640 
                 −278 
                 4.0 
               
               
                 15-Nov 
                 E 
                 5.5 
                 455 
                 225 
                 1160 
                 0 
                 1160 
                 −435 
                 4.0 
               
               
                 15-Nov 
                 F 
                 5.5 
                 430 
                 235 
                 1160 
                 0 
                 1160 
                 −312 
                 4.0 
               
               
                 16-Nov 
                 A 
                 5 
                 380 
                 190 
                 1020 
                 27 
                 993 
                 −414 
                 4.0 
               
               
                 5-Dec 
                 A 
                 4.5 
                 200 
                 110 
                 500 
                 35 
                 465 
                 −439 
                 4.0 
               
               
                 18-Nov 
                 A 
                 5 
                 360 
                 190 
                 200 
                 0 
                 200 
                 −423 
                 4.0 
               
               
                 21-Nov 
                 A 
                 4 
                 320 
                 170 
                 800 
                 40 
                 760 
                 −429 
                 4.0 
               
               
                 22-Nov 
                 A 
                 3.75 
                 285 
                 190 
                 725 
                 21 
                 704 
                 −432 
                 4.0 
               
               
                 29-Nov 
                 A 
                 4.25 
                 310 
                 155 
                 750 
                 24 
                 726 
                 −439 
                 4.0 
               
               
                 2-Dec 
                 A 
                 3.75 
                 250 
                 120 
                 660 
                 26 
                 634 
                 −438 
                 4.0 
               
               
                 6-Dec 
                 A 
                 3 
                 150 
                 75 
                 540 
                 0 
                 540 
                 −441 
                 4.0 
               
               
                 17-Nov 
                 A 
                 5.5 
                 300 
                 160 
                 1010 
                 30 
                 980 
                 −414 
                 4.0 
               
               
                 averages 
                   
                 4.81 
                 324 
                 164 
                 830 
                 13 
                 817 
                 −392 
                 4.0 
               
               
                 16-Nov 
                 B 
                 5 
                 400 
                 200 
                 1125 
                 45 
                 1080 
                 −397 
                 4.5 
               
               
                 16-Nov 
                 D 
                 5 
                 400 
                 165 
                 960 
                 60 
                 900 
                 −360 
                 4.5 
               
               
                 16-Nov 
                 E 
                 5 
                 490 
                 240 
                 1100 
                 72 
                 1028 
                 −324 
                 4.5 
               
               
                 1-Dec 
                 B 
                 3.5 
                 500 
                 260 
                 570 
                 45 
                 525 
                 −415 
                 4.5 
               
               
                 6-Dec 
                 B 
                 3 
                 470 
                 240 
                 650 
                 40 
                 610 
                 −411 
                 4.5 
               
               
                 21-Nov 
                 B 
                 4 
                 560 
                 300 
                 930 
                 50 
                 880 
                 −397 
                 4.5 
               
               
                 2-Dec 
                 B 
                 3.75 
                 640 
                 320 
                 830 
                 50 
                 780 
                 −407 
                 4.5 
               
               
                 17-Nov 
                 B 
                 5.5 
                 450 
                 220 
                 1165 
                 50 
                 1115 
                 −406 
                 4.5 
               
               
                 18-Nov 
                 B 
                 5 
                 390 
                 220 
                 860 
                 42 
                 818 
                 −406 
                 4.5 
               
               
                 22-Nov 
                 B 
                 3.75 
                 585 
                 395 
                 835 
                 50 
                 785 
                 −397 
                 4.5 
               
               
                 29-Nov 
                 B 
                 4.25 
                 620 
                 320 
                 920 
                 42 
                 878 
                 −410 
                 4.5 
               
               
                 5-Dec 
                 B 
                 4.5 
                 390 
                 190 
                 750 
                 37 
                 713 
                 −417 
                 4.5 
               
               
                 16-Nov 
                 F 
                 5 
                 400 
                 200 
                 1082 
                 96 
                 989 
                 −324 
                 4.5 
               
               
                 16-Nov 
                 C 
                 5 
                 400 
                 200 
                 950 
                 74 
                 876 
                 −325 
                 4.6 
               
               
                 averages 
                   
                 4.45 
                 478 
                 248 
                 909 
                 54 
                 856 
                 −385 
                 4.5 
               
               
                   
               
             
          
           
               
                   
                 COD 
                 Performance 
               
             
          
           
               
                   
                 Feed 
                 Effluent 
                 Removal 
                 Loading 
                 Consumed 
                 Total gas 
                 H2 
                 H2 
               
               
                 Date 
                 (mg/L) 
                 (mg/L) 
                 (mg/L) 
                 (g) 
                 (g) 
                 L/day 
                 L/day 
                 L/g COD 
               
               
                   
               
               
                 14-Nov 
                 4,480 
                 2,293 
                 2,187 
                 3.494 
                 1.706 
                 2.59 
                 1.06 
                 0.13 
               
               
                 14-Nov 
                 4,480 
                 2,453 
                 2,027 
                 3.763 
                 1.702 
                 1.82 
                 1.06 
                 0.13 
               
               
                 14-Nov 
                 4,480 
                 2,293 
                 2,187 
                 3.896 
                 1.902 
                 1.68 
                 0.82 
                 0.09 
               
               
                 14-Nov 
                 4,480 
                 1,920 
                 2,560 
                 4.122 
                 2.355 
                 1.54 
                 0.62 
                 0.06 
               
               
                 14-Nov 
                 4,480 
                 2,773 
                 1,707 
                 4.122 
                 1.570 
                 1.15 
                 0.48 
                 0.06 
               
               
                 14-Nov 
                 3,307 
                 2,080 
                 1,227 
                 2.679 
                 0.994 
                 0.24 
                 0.12 
                 0.03 
               
               
                 15-Nov 
                 3,307 
                 3,787 
                   (480) 
                 3.621 
                 −0.525 
                 1.96 
                 1.00 
                 −0.44 
               
               
                 15-Nov 
                 3,307 
                 3,253 
                   54 
                 3.787 
                 0.061 
                 1.96 
                 1.03 
                 3.82 
               
               
                 15-Nov 
                 3,307 
                 3,520 
                   (213) 
                 2.116 
                 −0.136 
                 1.09 
                 0.57 
                 −0.95 
               
               
                 15-Nov 
                 3,307 
                 3,467 
                   (160) 
                 3.836 
                 −0.185 
                 1.99 
                 0.96 
                 −1.21 
               
               
                 15-Nov 
                 3,307 
                 3,413 
                   (106) 
                 3.836 
                 −0.123 
                 1.88 
                 1.03 
                 −1.91 
               
               
                 16-Nov 
                 4,693 
                 3,627 
                 1,066 
                 4.660 
                 1.059 
                 1.82 
                 0.91 
                 0.18 
               
               
                 5-Dec 
                 4,267 
                 4,160 
                   107 
                 1.984 
                 0.050 
                 1.07 
                 0.59 
                 2.21 
               
               
                 18-Nov 
                 3,680 
                 5,227 
                 (1,547) 
                 0.736 
                 −0.309 
                 1.73 
                 0.91 
                 −0.61 
               
               
                 21-Nov 
                 3,493 
                 3,680 
                   (187) 
                 2.655 
                 −0.142 
                 1.92 
                 1.02 
                 −1.20 
               
               
                 22-Nov 
                 4,107 
                 2,293 
                 1,813 
                 2.891 
                 1.277 
                 1.82 
                 1.22 
                 0.15 
               
               
                 29-Nov 
                 5,013 
                 3,520 
                 1,493 
                 3.640 
                 1.084 
                 1.75 
                 0.88 
                 0.14 
               
               
                 2-Dec 
                 4,587 
                 3,893 
                   694 
                 2.906 
                 0.440 
                 1.60 
                 0.77 
                 0.27 
               
               
                 6-Dec 
                 4,853 
                 3,093 
                 1,760 
                 2.621 
                 0.950 
                 1.20 
                 0.60 
                 0.08 
               
               
                 17-Nov 
                 4,907 
                 3,520 
                 1,387 
                 4.809 
                 1.359 
                 1.31 
                 0.70 
                 0.12 
               
               
                 averages 
                 4,092 
                 3,213 
                   879 
                 3.344 
                 0.718 
                 1.61 
                 0.82 
                 0.23 
               
               
                 16-Nov 
                 4,693 
                 3,520 
                 1,173 
                 5.068 
                 1.267 
                 1.92 
                 0.96 
                 0.16 
               
               
                 16-Nov 
                 4,693 
                 3,573 
                 1,120 
                 4.224 
                 1.008 
                 1.92 
                 0.79 
                 0.16 
               
               
                 16-Nov 
                 4,693 
                 3,413 
                 1,280 
                 4.824 
                 1.315 
                 2.35 
                 1.15 
                 0.18 
               
               
                 1-Dec 
                 5,173 
                 3,680 
                 1,493 
                 2.716 
                 0.784 
                 3.43 
                 1.78 
                 0.33 
               
               
                 6-Dec 
                 4,853 
                 3,360 
                 1,493 
                 2.960 
                 0.911 
                 3.76 
                 1.92 
                 0.26 
               
               
                 21-Nov 
                 3,493 
                 3,147 
                   346 
                 3.074 
                 0.305 
                 3.36 
                 1.80 
                 0.98 
               
               
                 2-Dec 
                 4,587 
                 3,413 
                 1,174 
                 3.578 
                 0.915 
                 4.10 
                 2.05 
                 0.35 
               
               
                 17-Nov 
                 4,907 
                 2,933 
                 1,974 
                 5.471 
                 2.201 
                 1.96 
                 0.96 
                 0.10 
               
               
                 18-Nov 
                 3,680 
                 2,960 
                   720 
                 3.010 
                 0.589 
                 1.87 
                 1.06 
                 0.37 
               
               
                 22-Nov 
                 4,107 
                 2,720 
                 1,387 
                 3.224 
                 1.089 
                 3.74 
                 2.53 
                 0.36 
               
               
                 29-Nov 
                 5,013 
                 3,307 
                 1,707 
                 4.402 
                 1.496 
                 3.50 
                 1.81 
                 0.21 
               
               
                 5-Dec 
                 4,267 
                 3,840 
                   427 
                 3.042 
                 0.304 
                 2.08 
                 1.01 
                 0.62 
               
               
                 16-Nov 
                 4,693 
                 3,093 
                 1,600 
                 4.641 
                 1.582 
                 1.92 
                 0.96 
                 0.13 
               
               
                 16-Nov 
                 4,693 
                 2,933 
                 1,760 
                 4.111 
                 1.541 
                 1.92 
                 0.96 
                 0.13 
               
               
                 averages 
                 4,539 
                 3,278 
                 1,261 
                 3.883 
                 1.079 
                 2.58 
                 1.34 
                 0.23 
               
               
                   
               
             
          
         
       
     
         [0049]    Samples of biogas were analyzed several times per week from the beginning of the study, initially using a Perkin Elmer Autosystem GC with TCD, and then later with a Perkin Elmer Clarus 500 GC with TCD in series with an FID. Methane was never detected with the TCD, but trace amounts were detected with the FID (as much as about 0.05%). 
         [0050]    Over a ten-day period, the organic feed material was mixed with sludge obtained from a methane-producing anaerobic digester at a nearby wastewater treatment plant at a rate of 30 mL of sludge per 20 L of diluted grape juice. There was no observed increase in the concentration of methane during this period. Therefore, it was concluded that the preheating of the feed to 65° C. as described previously was effective in deactivating the microorganisms contained in the sludge. Hydrogen gas production rate was not affected. 
         [0051]    Using this example, hydrogen gas was generated using a microbial culture over a sustained period of time. The optimal pH for this culture consuming simple sugars from a simulated fruit juice bottling wastewater was found to be 5.0. Under these conditions, using plastic packing material to retain microbial biomass, a hydraulic residence time of about 0.5 days resulted in the generation of about 0.75 volumetric units of hydrogen gas per unit volume of bioreactor per day. 
         [0052]    Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.