Microbial reduction of SO2 and NOx as a means of by-product recovery/disposal from regenerable processes for the desulfurization of flue gas. Technical progress report, September 11, 1992--December 11, 1992

摘要

With the continual increase in the utilization of high sulfur and high nitrogen containing fossil fuels, the release of airborne pollutants into the environment has become a critical problem. The fuel sulfur is converted to SO(sub 2) during combustion. Fuel nitrogen and a fraction of the nitrogen from the combustion air are converted to nitric oxide and nitrogen dioxide, NO(sub x). For the past five years Combustion Engineering (now Asea Brown Boveri or ABB) and, since 1986, the University of Tulsa (TU) have been investigating the oxidation of H(sub 2)S by the facultatively anaerobic and autotrophic bacterium Thiobacillus denitrificans and have developed a process, concept for the microbial removal of H(sub 2)S from a gas stream the simultaneous removal Of SO(sub 2) and NO by D. desulfuricans and T. denitrificans co-cultures and cultures-in-series was demonstrated. These systems could not be sustained due to NO inhibition of D. desulfuricans. However, a preliminary economic analysis has shown that microbial reduction of SO(sub 2) to H(sub 2)S with subsequent conversion to elemental sulfur by the Claus process is both technically and economically feasible if a less expensive carbon and/or energy source can be found. It has also been demonstrated that T. denitrificans can be grown anaerobically on NO(g) as a terminal electron acceptor with reduction to elemental nitrogen. Microbial reduction of NO(sub x) is a viable process concept for the disposal of concentrated streams of NO(sub x) as may be produced by certain regenerable processes for the removal of SO(sub 2) and NO(sub x) from flue gas.