System for the Production of Methane From CO2

Abstract

A method of converting CO 2 gas produced during industrial processes comprising contacting methanogenic archaea with the CO 2 gas under suitable conditions to produce methane.

1 .- 29 . (canceled) 
     
     
         30 . A method of producing methane gas, comprising:
 a. supplying hydrogen gas and carbon dioxide gas to a bioreactor system comprising (i) at least three vessels or (ii) a single vessel comprising at least three zones comprising a mixing apparatus, wherein at least three vessels or the single vessel with at least three zones of the bioreactor system comprises a culture of hydrogenotrophic methanogenic archaea, wherein the amount of carbon dioxide in the bottom zone of the single vessel differs from the amount of carbon dioxide in the top zone of the single vessel or, when the bioreactor system comprises at least three vessels, the amount of carbon dioxide in the first vessel differs from the amount of carbon dioxide in the last vessel; and   b. removing methane gas from the bioreactor system.   
     
     
         31 . The method of  claim 30 , comprising adding fresh medium to the culture. 
     
     
         32 . The method of  claim 31 , wherein fresh medium is added to the culture to maintain a dilution rate of less than 0.1 culture volume per hour. 
     
     
         33 . The method of  claim 31 , wherein fresh medium is added to the culture to maintain a dilution rate of less than 0.001 culture volume per hour. 
     
     
         34 . The method of  claim 30 , comprising removing spent medium from the culture. 
     
     
         35 . The method of  claim 30 , wherein the hydrogen gas and carbon dioxide gas are supplied to the bottom zone of the single vessel or the bottom of the first vessel of the bioreactor system. 
     
     
         36 . The method of  claim 30 , comprising supplying an industrial process output gas to the bioreactor system which industrial output gas comprises carbon dioxide and (i) air or (ii) carbon monoxide or (iii) both air and carbon monoxide, wherein the air or carbon monoxide is at least intermittently supplied to the bioreactor system. 
     
     
         37 . The method of  claim 36 , wherein about 32% or less air by volume output gas is supplied to the bioreactor system. 
     
     
         38 . The method of  claim 37 , wherein less than about 4% air by volume output gas is supplied to the bioreactor system. 
     
     
         39 . The method of  claim 36 , wherein less than about 40% carbon monoxide by volume output gas is supplied to the bioreactor system. 
     
     
         40 . The method of  claim 30 , wherein the pressure of the bioreactor system is maintained at about 0.5 atmospheres to about 500 atmospheres. 
     
     
         41 . The method of  claim 30 , wherein the culture comprises a hydrogenotrophic methanogenic archaea selected from the group consisting of:
   Methanobacterium alcallphilum, Methanobacterium btyantil, Methanobacterium congolense, Methanobacterium defluvii, Methanobacterium espanolae, Methanobacterium formicicum, Methanobacterium ivanovii, Methanobacterium palustre, Methanobacterium thermaggregans, Methanobacterium uliginosum, Methanobrevibacter acididurans, Methanobrevibacter arboriphilicus, Methanobrevibacter gottschalkii, Methanobrevibacter olleyae, Methanobrevibacter ruminantium, Methanobrevibacter smithii, Methanobrevibacter woesei, Methanobrevibacter wolinii, Methanothermobacter marburgensis, Methanothermobacter thermautotrophicum, Methanothermobacter thermoflexus, Methanothermobacter thermophilus, Methanothermobacter wolfeii, Methanothermus sociabilis, Methanocorpusculum bavaricum, Methanocorpusculum parvum, Methanoculleus chikuoensis, Methanoculleus submarinus, Methanogenium .frigidum, Methanogenium liminatans, Methanogenium marinum, Methanosarcina acetivorans, Methanosarcina barkeri, Methanosarcina mazei, Methanosarcina thermophila, Methanomicrobium mobile, Methanocaldococcus jannaschii, Methanococcus aeolicus, Methanococcus maripaludis, Methanococcus vannielii, Methanococcus voltaei, Methanothermococcus thermolithotrophicus, Methanopyrus kandleri, Methanothermobacter the rmoautotroiphicus, Methanocaldococcus fervens, Methanocaldococcus indicus, Methanocaldococcus infernus , and  Methanocaldococcus vulcanius.      
     
     
         42 . The method of  claim 41 , wherein the culture comprises  Methanococcus maripaludis, Methanosarcina barkeri , or  Methanothermobacter thermautotrophicus.    
     
     
         43 . The method of  claim 30 , wherein the culture is maintained at a temperature of about 60 degrees C. to about 65 degrees C. 
     
     
         44 . The method of  claim 30 , wherein the methane gas removed from the bioreactor comprises less than about 450 ppm hydrogen sulfide. 
     
     
         45 . The method of  claim 30 , wherein the methane gas removed from the bioreactor comprises less than about 100 ppm hydrogen sulfide. 
     
     
         46 . The method of  claim 30 , wherein each mixing apparatus is controlled by a mechanical impeller. 
     
     
         47 . The method of  claim 30 , wherein the amount of carbon dioxide decreases from the bottom zone to the top zone of the bioreactor or from the first vessel to the last vessel. 
     
     
         48 . The method of  claim 30 , wherein the bioreactor system comprises:
 a first reactor vessel that extends along a first longitudinal axis from a first end to a second end opposite the first end, the first reactor vessel including an interior volume, wherein a first inlet is disposed at or adjacent to the first end of the first reactor vessel such that the first inlet is in fluid communication with the interior volume, and wherein a first outlet is disposed at or adjacent to the second end of the first reactor vessel such that the first outlet is in fluid communication with the interior volume;   a second reactor vessel that extends along a second longitudinal axis from a first end to a second end opposite the first end, the second reactor vessel including an interior volume, wherein a first inlet is disposed at or adjacent to the first end of the second reactor vessel such that the first inlet is in fluid communication with the interior volume, and wherein a first outlet is disposed at or adjacent to the second end of the second reactor vessel such that the first outlet is in fluid communication with the interior volume;   a first conduit disposed between the first outlet of the first reactor vessel and the first inlet of the second reactor vessel such that the first outlet of the first reactor vessel is in fluid communication with the first inlet of the second reactor vessel;   a third reactor vessel that extends along a third longitudinal axis from a first end to a second end opposite the first end, the third reactor vessel including an interior volume, wherein a first inlet is disposed at or adjacent to the first end of the third reactor vessel such that the first inlet is in fluid communication with the interior volume, and wherein a first outlet is disposed at or adjacent to the second end of the third reactor vessel such that the first outlet is in fluid communication with the interior volume; and   a second conduit disposed between the first outlet of the second reactor vessel and the first inlet of the third reactor vessel such that the first outlet of the second reactor vessel is in fluid communication with the first inlet of the third reactor vessel,   wherein the first longitudinal axis of the first reactor vessel, the second longitudinal axis of the second reactor vessel, and the third longitudinal axis of the third reactor vessel are each vertical;   wherein:   the first reactor vessel includes a second inlet disposed at or adjacent to the first end of the first reactor vessel such that the second inlet is in fluid communication with the interior volume of the first reactor vessel; or   the second reactor vessel includes a second inlet disposed at or adjacent to the first end of the second reactor vessel such that the second inlet is in fluid communication with the interior volume of the second reactor vessel; or   the third reactor vessel includes a second inlet disposed at or adjacent to the first end of the second reactor vessel such that the second inlet is in fluid communication with the interior volume of the third reactor vessel.   
     
     
         49 . The reactor system of  claim 48 , wherein the first end of the first reactor vessel, the first end of the second reactor vessel, and the third end of the third reactor vessel are horizontally aligned. 
     
     
         50 . The method of  claim 30 , wherein the reactor system comprises an anaerobic fermenter.