Microbial Reduction of Sulfur Dioxide in Immobilized, Mixed Cultures of Sulfate-Reducing Bacteria with Sewage Digest as Carbon and Energy Source

Abstract

Sulfur dioxide (SO2) gas is one of the most abundant air pollutants emitted in the US. The quantity emitted in the US in 1992 was estimated to be 22.73 million tons (1). About 70% of the total emissions are from fossil fuel combustion. In the atmosphere, SO2reacts photochemically or catalytically with other constituents to form sulfuric acid or acid rain. In this article, we demonstrate a microbial process for the reduction of sulfur dioixde utilizing mixed cultures of sulfate-reducing bacteria (SRB). The cost of feed stock and the productivity of bioreactor are identified as key factors for the economic viability of the microbial process. In these regards, we have developed a continuous process of producing sewage digest, an inexpensive carbon and energy source, and have investigated the immobilization of mixed cultures of SRB in order to increase the productivity of the process.