Microbial reduction of sulfur dioxide with pretreated sewage sludge and elemental hydrogen as electron donors.

It has been demonstrated tht heat- and alkali-pretreated-sewage sludge may serve as an electron donor and carbon source for SO2 reduction by Desulfovibrio desulfuricans. A continuous D. desulfuricans culture was operated for 6 mo with complete reduction of SO2 to H2S. The culture required only minor amounts of mineral nutrients in addition to pretreated sewage sludge. It has also been shown that the sulfate-reducing bacterium Desulfotomaculum orientis can be grown on H2 as an energy source, CO2 as a carbon source, and SO2 as a terminal electron acceptor. Complete reduction of SO2 to H2S was observed.