CO2 Sequestration in Cell Biomass of Chlorobium Thiosulfatophilum

75874S Worldwide carbon dioxide emissions from the combustion of fossil fuels have increased at a rate of about 3 percent per year during the last 40 years to over 24 billion tons today. One candidate technology for dealing with the carbon dioxide problem involves the anaerobic bacterium Chlorobium thiosulfatophilum, which uses hydrogen sulfide and carbon dioxide to produce elemental sulfur and cell biomass. This project will develop a commercial process for the biological sequestration of carbon dioxide along with the simultaneous conversion of hydrogen sulfide to elemental sulfur. Phase I demonstrated technical and economic feasibility by utilizing the bacterium in continuous reactor studies. Economic projections showed that low quality natural gas (LQNG) can be desulfurized for about $0.23/MSCF, while subsequently converting stoichiometric quantities of carbon dioxide. Phase II will develop the engineering and scale-up parameters for commercialization of the technology. Tasks include culture isolation and optimization studies, further continuous reactor studies, light delivery studies, high-pressure studies, process scale-up, and economic projections. Commercial Applications and Other Benefits as described by the awardee: In addition to the sequestration of carbon dioxide in cell biomass, the technology should have immediate application in desulfurizing LQNG or other gas streams. This biological approach should be a viable economical alternative to existing hydrogen sulfide removal technology, because it would not be sensitive to the presence of hydrocarbons acting as catalyst poisons.