Desulphurization and denitrification of gas and liquid streams with concomitant generation of energy in microbial fuel cells

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H2S is a highly toxic and corrosive gas present in the natural gas and biogas. Sulphide is also an undesirable component of many wastewaters. Removal of H2S is essential due to its harmful characteristics and for preventing emission of SO2 upon combustion of fuels. Biotreatment of sulphide-laden streams is attractive due to economic advantages, feasibility for treatment of small streams and high efficiency. We have been investigating the potential of Thiomicrospira CVO, a novel sulphide oxidizer isolated from a Canadian oil field, for the removal of sulphide from the liquid streams. CVO is an autotroph which uses sulphide as an electron donor, nitrate as an electron acceptor and CO2 as the sole carbon source. Physiological characteristics of CVO make it suitable for simultaneous removal of sulphide and nitrate from contaminated streams. The first objective of the current proposal is to expand our ongoing research and utilize CVO for the removal of H2S from gaseous streams and generate fundamental knowledge which is crucial for the design and operation of a large scale process. Generation of electricity in microbial fuel cells as a form of renewable energy is gaining momentum. This technology enables direct capture of energy contained in biodegradable compounds, specially in wastewaters, in the form of electricity. To date microbial fuel cells have been used mainly for the treatment of organic wastewaters and only a few studies have dealt with sulphide-containing streams. Moreover, the possibility of simultaneous desulphurization and denitrification in a microbial fuel cell has not been evaluated. The second objective of the current proposal is to study the processes of desulphurization and denitrification in a microbial fuel cell. The basic information generated in our research would significantly increase our understanding of the processes of biodesulphurization and denitrification and the extent of energy which can be extracted from these processes. It will provide us with fundamental information required for the development of an innovative biotechnology for treatment of H2S and nitrate with the possibility of capturing CO2 and electricity generation in fuel cell type bioreactors, the long term objective of our research.