Abstract:
Methods for increasing methane emitted from organic waste and for collecting methane and other gaseous bi-products. A gas collection unit collects gas in a first separation tank, wherein the gas is separated into methane and other components. The methane is collected, and other components are diverted. A second separation tank receives diverted components combined with an acidic solution and further separates the components into carbon dioxide and other compounds. The carbon dioxide is collected for reuse in a variety of applications.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 61/181,759, filed May 28, 2009, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. The Field of the Invention 
         [0003]    This invention relates generally to virus resistant microorganisms and methods to separate gases. More particularly, embodiments of the present invention relate to processes for using virus resistant microorganisms in applications relating to the aerobic digestion of waste and the separation of gases produced during such processes. 
         [0004]    2. Related Technology 
         [0005]    Methane is one of the primary contributors to global warming. Though methane is mentioned less frequently than carbon dioxide as a gas that contributes to global warming, a molecule of methane absorbs twenty to twenty-six times as much heat as a molecule of carbon dioxide. 
         [0006]    Methane is released from a variety of different sources, such as, for example, sewage lagoons, ponds, garbage landfills, coal-fired plants, uncapped natural gas wells on land and in the ocean, swampy areas, and from certain ponds and lakes that contain organic matter. 
         [0007]    While some methane is produced from these sources spontaneously, other methane emissions result as a bi-product from biological and/or chemical processes, or may be increased from these sources by such processes. For example, manure that is biologically treated may release more methane than untreated manure. 
         [0008]    As manure and other organic matter is treated, bacteria are often used to aid in digestion of the manure. Bacteria and other microorganisms, however, are susceptible to infection by viruses. Certain estimations place the number of viruses in the environment at an amount ten times that of the number of bacteria. Many of the bacteria involved in the digestion of manure are, therefore, killed by viruses. The population of bacteria present to digest manure can be restored by the growth of bacteria that mutate and become resistant to infection, thus creating a great fluctuation in the bacterial population levels involved in the digestion of manure. Such fluctuations in the bacterial population levels affect the amount of methane produced by processes using bacteria to digest manure or other matter. Moreover, methane released from areas where such processes take place is often released directly into the air. 
         [0009]    Embodiments of the present invention provide ways to increase methane produced in anaerobic digestion of manure and other organic matter and collect methane produced in these processes, thereby maximizing methane produced in waste management processes, preventing methane from being released directly into the air, and collecting methane to be used for a variety of energy efficient purposes. Embodiments of the present invention may also be used to collect gases released from coal-fired plants and other sources of gaseous waste and to separate and collect these gases for use in a variety of applications. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    Embodiments of the present invention include methods for increasing production of methane from human and animal waste. The methane and other gases produced are collected and separated in gas collection units. These gases are then collected for use in other applications, rather than being emitted into the air as waste. 
         [0011]    These and other aspects of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    To further clarify the above and other aspects of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The drawings are not drawn to scale. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0013]      FIG. 1  shows a chart depicting a process for increasing methane production from waste products; 
           [0014]      FIG. 2  shows an embodiment of a gas separation container; and 
           [0015]      FIG. 3  shows a chart depicting a process for determining phage resistance of bacteria. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0016]    Embodiments of the present invention relate to increasing production of methane from organic waste and collection and separation of methane and other gases. Methane and other gases are emitted from a variety of sources, such as, for example, coal-fired plants, outdoor sewage lagoons, and so forth. For sources of methane produced due to anaerobic digestion of organic material, embodiments of the present invention provide methods for increasing methane production, while decreasing production of other undesirable gases. In addition, embodiments of the present invention provide a gas collection unit for collecting methane (CH 4 ) from a variety of sources, include bio-gas and hot smoke stack gas sources. 
         [0017]    Embodiments of the present invention show anaerobic system using bacteria resistant to bacteria viruses, often referred to as bacteriophages or phages, to produce methane from manure. These bacteria that are resistance to bacteria viruses are also referred to as phage-resistant bacteria. While descriptions are provided for preparing phage resistant bacteria, embodiments of the present invention also apply to other microorganisms such as, for example, protozoa and fungi. As shown in embodiments of the present invention, these virus resistant microorganisms can be used is the aerobic and anaerobic treatment of all human and animal waste. Moreover, as shown in other embodiments of the present invention, virus resistant microorganisms can also be used in the production of methane from cellulose and sugars. 
         [0018]    The digestion of cellulose to produce methane begins in the rumen, a part of the stomach, of animals. In the rumen, a steady state exists between bacteria and viruses that attack these bacteria. Within the rumen, bacteria susceptible to infecting viruses may be partially or totally destroyed by viruses, depending on the susceptibility of the bacteria to the viruses. The destruction of bacteria by viruses may also depend on the burst size of the viruses. 
         [0019]    As virus-sensitive bacteria are destroyed, other bacteria that are of the same species as the destroyed bacteria but that are resistant to the infecting virus or viruses, grow to keep the population of bacteria and viruses in balance. Over time the population of bacteria develops into a more resistant population. While this new population may be more resistant to viruses than the original population, the new population may still be susceptible to new viruses that may appear, or to viruses that may adapt. This new population of bacteria, also referred to as phage-resistant bacteria, is parts of a mixed group of bacteria and other microorganisms found in the rumen. 
         [0020]    While this group of microorganisms is most beneficial for the health of the animal, it may not represent the best microbial population for the production of methane. Thus, as shown in stage  102  of  FIG. 1 , embodiments of the present invention include inoculating large numbers of selected bacteria into animal manure. The selected bacteria refer to bacteria that represent the best microbial population for the production of methane. 
         [0021]    After the selected bacteria are inoculated into the manure, embodiments of the present invention provide for optimization of fermentation conditions to maximize the production of methane, as shown at stage  104 . In one embodiment of the invention, optimization of fermentation conditions includes, for example, optimizing the pH, temperature, substrate, moisture conditions, nutrients, and so forth. In one embodiment of the invention, as shown at stage  106 , a phage monitoring system, or plague assay, is implemented to make certain that the large populations of selected bacteria are not affected by the appearance of an infected phage. 
         [0022]    In addition to implementation of a phage monitoring system, a mutant-derivation program is also implemented. The mutant-derivation program ensures that methane fermentations progress under optimal microbial conditions. This is shown in  FIG. 1  at stage  108 . 
         [0023]    With attention now to  FIG. 1 , chart  100  shows a method for increasing methane production from organic solids. At stage  102 , large numbers of selected bacteria are inoculated into organic matter to “out compete” other organisms. At stage  104 , fermentation conditions are optimized to maximize the production of methane. Such optimization may include, for example, optimization of pH, temperature, substrate, and so forth. Then at stage  106 , a phage monitoring system, and mutant-derivation program are implemented to ensure that methane fermentations are progressing under optimal microbial conditions. Moreover, the presence of undesirable gases in the system is reduced, as shown at stages  108  and  110 . First, at stage  108 , phages are added to anaerobic digesters to kill microorganisms that digest proteins to produce undesirable gases. Examples of undesirable gases include hydrogen sulfide, nitrogen oxides, and ammonia. Finally, at stage  110  organic waste is inoculated with large numbers of cellulose digesting bacteria so that protein digesting bacteria is unable to compete for nutrients. Thus, the growth of protein digesting bacteria is greatly restricted and the emission of undesirable gases is also restricted. 
         [0024]    With attention now to  FIG. 2 , a gas collection and separation unit  200  is shown. As noted above, gas collection unit  200  may be used in such applications as, for example, collection of bio-gas and collection of hot smoke stack gas, such as hot smoke stack gas released from coal-fired plants. Gas collection units of the present invention may be constructed of plastics, such as, for example, soft, gas-impermeable, inflatable plastic, or hard plastic. Gas collection unit  200  includes opening  202 , entry pump  204 , heat exchanger  206 , and sparger  208 . Gas collection unit  200  also includes a first separation tank  210 , and pipe  212 , having openings  214  and  216 . Further, a valve  218  and emission opening  220 , and a pipe  222 , connect the top of first separation tank  210 . Pipe  222  also connects to heat exchanger  206 . 
         [0025]    Gas collection unit  200  also includes a second separation tank  224 , connected to heat exchanger  206  by pipe  226 . Pipe  226  further includes influx opening  228  and a pressure release valve  230 . Cooling coils  232 , located at the bottom of second separation tank  224 , include input opening  234  and output opening  236 . Compressor  238 , attached to the top of second separation tank  224 , includes opening  240 . 
         [0026]    In operation, bio-gas or hot smoke stack gas enters opening  202  and moves through entry pump  204  to heat exchanger  206 . In applications where bio-gas is collected in gas collection unit  200 , the bio-gas is first assayed to determine the ratio of the volume of methane to the volume of carbon dioxide. This ratio is then used to determine the location of the entry port of the bio-gas into the gas collection unit, or, stated differently, to determine where the entry port should be placed. In one embodiment of the invention the entry port is opening  202 . 
         [0027]    From heat exchanger  206 , the gas moves into, or may be, in other instances, pumped into, sparger  208 . Sparger  208  introduces the gas into water, such as alkaline water, contained in first separation tank  210 . Water enters first separation tank  210  through opening  214  attached to pipe  212 , while sodium hydroxide (NaOH) enters pipe  212  through opening  216 . The water present in first separation tank  210  increases the solubility of carbon dioxide (CO 2 ) gas entering into first separation tank  210 . Hydroxide, carbonates, and bicarbonate salts of sodium, potassium, ammonium, and so forth, can be used to produce alkalinity solutions. Alkaline water saturated with carbon dioxide will remain in solution during the release of methane. 
         [0028]    As methane is released, the methane is exhausted through valve  218  and emission opening  220 . Water soluble gases, such as carbon dioxide and hydrogen sulphide (H 2 S) circulate through pipe  222  and pass through heat exchanger  206 , once the solution in first separation tank  210  is saturated. 
         [0029]    As the gas solution passes through pipe  226 , acidic solution is added to the gas solution phase through influx opening  228 . Pressure release valve  230  releases the acidic solution, as a mist, into second separation tank  224 . The heat, acidic solution, and misting combine to help increase the rate at which carbon dioxide gas is released in second separation tank  224 . 
         [0030]    Cooling coils  232 , having an opening  234  for water input and an opening  236  for water output, help with water condensation and gas separation. During the summer and warmer months, the coils may be cooled by a refrigeration unit. During winter and colder months, the coils are cooled by the ambient air. Alternatively, moisture can be removed by passing gases through a desiccant before or after the gases pass through second separation tank  224 . 
         [0031]    As carbon dioxide is collected in second separation tank  224 , it passes into compressor  238  and is collected through opening  240 . After collection, the carbon dioxide can be used in a variety of different applications, including, for example, oil sequestration in oil fields. 
         [0032]    With continued attention to  FIG. 2 , the following description also shows functionality of the gas collection and separation unit  200 . In one embodiment of the invention, unit  200  is configured to be attached to or coupled to a covering placed over a methane production source. For example, unit  200  may be attached to a covering that is placed over a methane source, such as, for example, organic solids. In one embodiment of the invention, unit  200  may be attached to a covering that covers organic solids whose methane production has been enhanced by processes described in reference to  FIG. 1 . In other embodiments of the invention, unit  200  may be couple to hosing extending from a covering of a methane source, rather than attaching directly to the covering. In yet another embodiment of the invention, unit  200  may attach to or be couple to other methane sources, such as, for example, smoke stacks from coal-fired plants, natural gas wells, and any other methane source. 
         [0033]    Methane released from a source enters unit  200  through opening  202 . In one embodiment of the invention, methane is further drawn into unit  200  by entry pump  204  and pumped through sparger  208 . In one embodiment of the invention, sparger  208  is a unit configured with fine or very fine holes through which the gas passes, thus increasing the surface area of the gas. Passing the gas through a sparger in this way may increase the solubility of the gas. For example, in one embodiment of the invention where carbon dioxide enter unit  200  through opening  202  and is pumped by entry pump  204  through sparger  208 , the rate of carbon dioxide solubility is faster because the surface area of carbon dioxide bubbles that are created to pass through water contained in first separation tank  210  is increased. This effect, increasing the solubility of carbon dioxide by breaking up large carbon dioxide bubbles into small carbon dioxide bubbles, is achieved by passing the carbon dioxide through a sparger, such as, for example, sparger  208 . 
         [0034]    As noted above, after passing through sparger  208 , gas enters alkaline water tank  210 . Alkaline water tank  210  contains water with increased alkalinity. The increased alkalinity of water tank  210  functions to increase the solubility of carbon dioxide in the tank  210 . In one embodiment of the invention, hydroxide, carbonates, bicarbonates of salts and sodium, potassium, ammonium, and other substances may be used to create the alkaline solution. While methane will be released from the alkaline water solution held in tank  210 , the alkaline water saturated with carbon dioxide will remain in solution during the release of the methane. In one embodiment of the invention, methane is exhausted through opening  220 . In one embodiment of the invention, opening  220  connects to an exhaust valve  218 . 
         [0035]    While methane from bio-gas or smoke-stack gas that has entered the unit  200  through opening  202  may be released through opening  220 , water soluble gases, including, for example, carbon dioxide and hydrogen sulfide, circulate through passage  222  after the water in tank  210  becomes saturated. In one embodiment of the invention, such water soluble gases pass through heat exchange  206  and into passage  226 . These gases enter tank  224 . In one embodiment of the invention, an acidic solution is added to the gas solution phase of the gases that are entering tank  224 . In another embodiment of the invention, the acidic solution is released into tank  224  through a pressure release valve  230 . Thus, in one embodiment of the invention, the acidic solution enters tank  224  as a mist. The heat contributed by heat exchange  206 , the addition of the acidic solution, and the misting help the carbon dioxide gas to be released more quickly in the tank  224 . The process of gas separation is further enhanced by cooling coils  232  that function in part to condense water, such as, for example, water vapor that may be saturated with carbon dioxide. Finally, compressor  238  compresses the carbon dioxide with passes through opening  240  and may be collected for a variety of uses, including, for example, oil sequestration in oil fields. Embodiments of the gas collection and separation unit as described with reference to  FIG. 2  may be used in conjunction with anaerobic systems used in the production of methane as described herein and with systems and methods as described with reference to  FIGS. 1 ,  3 , and  4 . 
         [0036]    With attention now to  FIG. 3 , a process for determining phage patterns and phage host ranges for bacteria is shown. First, at stage  302 , phage patterns and phage host ranges for methane producers in rumen are determined. The species that contribute to cellulose breakdown and methane production in bovines are determined, as shown at stage  304 . The isolated species are cultured, as shown at stage  306 , and the phage resistance of the isolated species is determined, as shown at stage  308 . 
         [0037]    Within the rumen of bovines, one of the primary cellulose digesting bacteria is  Streptococcus bovis , which exhibits a greatly reduced phage host range. Such bacteria are typically infected only by a single or very small number of phages. Embodiments of the present invention include methods for determining the phage patterns and phage host ranges for  Methanobacter , the primary producer in the rumen of bovines. Moreover, embodiments of the present invention further include the isolation and culture of other species that work synergistically with the  Methanobacter  and Streptococci, in addition to a determination of their phage resistance. Finally, additional embodiments of the present invention include the addition of phage resistant cellulose digesting bacteria to the feed of animals to increase the rate of cellulose digestion, thus increasing milk production, and the addition of  Escherichia coli  phages to animal feed in feed lots prior to slaughter to reduce  E. coli  contamination in meat. 
         [0038]    With attention now to  FIG. 4 , a process for anaerobic digestion of manure by phage resistant bacteria is shown. In one embodiment of the invention, the anaerobic digestion of manure by phage resistant bacteria may take place in tanks containing a mixing device. A tank containing manure is inoculated with a large inoculum containing several different genera of phage resistant bacteria that digest cellulose, as shown at stage  402 . These bacteria outgrow the bacteria originally present in the manure. As the cellulose is digested the end product is organic solids. When the cellulose is mostly digested to form organic acids, a second large inoculums of phage resistant bacteria is added to the digester, as shown at stage  404 . These bacteria also outgrow microorganisms in the digester and convert the organic acids products in the first fermentation to carbon dioxide, hydrogen, and some small organic salts. 
         [0039]    As shown at stage  406 , the phage resistant bacteria added at the third stage of the digestion convert the carbon dioxide, hydrogen, and organic acids into methane. Throughout the digestion, the pH, moisture content, and temperature, are monitored and adjusted as needed to optimize each fermentation step, as shown at stage  408 . Nutrients are also monitored during each stage of fermentation and added as needed, as shown at stage  410 . In one embodiment of the invention, protozoa and fungi, which participate synergistically with bacteria in the production of methane from manure, are also used in the process described above. In one embodiment of the invention, these techniques are applied to the aerobic digestion of human sewage and garbage. 
         [0040]    Moreover, techniques included in embodiments of the present invention may be adapted for aerobic digestion of manure and waste such as that present in windrows, and any other aerobic system. Embodiments of the present invention further include using phage resistant bacteria to digest or pre-digest animal feed, grain, corn silage, and/or straw to improve feed efficiency and meat and milk production. Further, phage resistant bacteria may be used, in embodiments of the present invention, to treat straw, thatch, and crop residues in agricultural fields and post-harvest and pre-planting to breakdown residues and enhance the production of organic matter. In one embodiment of the invention, the inoculums is sprayed directly on crop residues and/or the soil and incorporated into the soil. Finally, embodiments of the present invention may further be used for thatch breakdown in instances such as after lawns are mowed on golf courses. In such instances phage resistant bacteria may be used to breakdown residues. 
         [0041]    Thus, embodiments of the present invention provide methods for not only anaerobic digestion of waste and increasing methane production from a variety of different waste sources, but also collecting and separating gases, such as, for example, bio-gases and hot smoke stack gases released from such sources as coal fired plants. Gases collected and separated according to embodiments of the present invention can then be used in a variety of different ways, rather than being discharged as waste into the atmosphere. 
         [0042]    The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.