Bioelectrochemical treatment of gaseous byproducts

Abstract

The present invention relates to a method for producing electrical energy or hydrogen gas from a gas stream containing one or more gaseous compounds that are oxidatively degradable by microbes, the method comprising contacting the gas stream with an anode of a bioelectrochemical device, said anode containing said microbes which oxidatively degrade one or more of said gaseous compounds while producing electrical energy or hydrogen gas by said oxidative degradation, wherein: (i) said anode is sufficiently porous such that gas is permitted to flow therethrough, (ii) said anode contains on its surface and/or interior portions a proton-conducting medium, and (iii) said anode is in electrical communication with a cathode of the bioelectrochemical device. The invention is also directed to a bioelectrochemical device (e.g., microbial fuel cell) configured to accomplish the above method.

1 . A method for producing electrical energy or hydrogen gas from a gas stream containing one or more gaseous compounds that are oxidatively degradable by microbes, the method comprising contacting the gas stream, as a gas-continuous stream, with an anode of a bioelectrochemical device, said anode containing said microbes which oxidatively degrade one or more of said gaseous compounds while producing electrical energy or hydrogen gas by said oxidative degradation, wherein: (i) said anode is sufficiently porous such that gas is permitted to flow therethrough, (ii) said anode contains on its surface and/or interior portions a proton-conducting liquid film that is maintained by an anode wetting process to maintain the liquid film, and (iii) said anode is in electrical communication with a cathode of the bioelectrochemical device. 
     
     
         2 . The method of  claim 1 , wherein said microbes are in the form of a biofilm on said anode. 
     
     
         3 . The method of  claim 1 , wherein said one or more gaseous compounds comprise a mercaptan compound and/or carbon monoxide. 
     
     
         4 . The method of  claim 1 , wherein said anode comprises a form of elemental carbon. 
     
     
         5 . The method of  claim 1 , wherein said anode is a three-dimensional electrode. 
     
     
         6 . The method of  claim 1 , wherein said anode has been previously rendered hydrophilic by a suitable surface treatment process. 
     
     
         7 . The method of  claim 6 , wherein the surface treatment process is a plasma treatment process. 
     
     
         8 . The method of  claim 1 , wherein the anode possesses a porosity value of at least 50%. 
     
     
         9 . The method of  claim 1 , wherein the anode possesses a specific surface area of at least 5,000 m 2 /m 3 . 
     
     
         10 . (canceled) 
     
     
         11 . The method of  claim 1 , wherein said proton-conducting liquid film has a thickness in the range of  1  micron and up to 10 microns. 
     
     
         12 . The method of  claim 1 , further comprising controlling the humidity level of the gas stream such that the humidity of the gas stream is at least 40% before entry of the gas stream into the bioelectrochemical device. 
     
     
         13 . The method of  claim 12 , wherein the humidity level of the gas stream is controlled by passing the gas stream through a column of water. 
     
     
         14 . The method of  claim 1 , wherein the gas stream emanates from a petroleum refining operation. 
     
     
         15 . The method of  claim 1 , wherein electricity or hydrogen produced from the bioelectrochemical device is used to power one or more mechanisms involved in an operation that produces the gas stream. 
     
     
         16 . The method of  claim 1 , wherein the bioelectrochemical device is operated such that hydrogen gas is produced at the cathode by operating the bioelectrochemical device under the conditions that the cathode is constructed of a hydrogen-producing material and is deoxygenated, and the cell potential of the bioelectrochemical device is adjusted by application of an external voltage such that hydrogen is produced at the cathode. 
     
     
         17 . The method of  claim 1 , wherein the bioelectrochemical device is operated such that the cathode electrochemically reduces one or more electrochemically reducible species other than hydrogen ions. 
     
     
         18 . The method of  claim 1 , wherein a cation-permeable material is in direct contact with said anode and cathode, and separates said anode and cathode. 
     
     
         19 .- 37 . (canceled) 
     
     
         38 . The method of  claim 1 , wherein said gas stream contains carbon monoxide. 
     
     
         39 . The method of  claim 38 , wherein said gas stream emanates from a biomass gasification operation. 
     
     
         40 . The method of  claim 38 , wherein the microbes on the anode are capable of effecting a water-gas shift reaction. 
     
     
         41 . The method of  claim 40 , wherein the microbes are selected from the group consisting of  Rubrivivax gelatinosus, Butyribacterium methylotrophicum, Clostridia,  and  Rhodospirillus rubrum.    
     
     
         42 . The method of  claim 1 , wherein said gas stream contains one or more mercaptans. 
     
     
         43 . The method of  claim 42 , wherein said gas stream is substantially absent of carbon monoxide.