Bioprocess engineering of sulfate reduction for environmental technology

Sulfate reduction can be used in a large number of environmental technologies. Methanogenic bioreactors treating organic wastewater containing sulfate can be negatively affected by the sulfide produced; however, it is possible to combine methanogenesis and sulfate reduction when adequate measures are applied. For the treatment of inorganic wastewaters containing sulfate, organic substrates or H-2/CO2 are added as electron donors. Alternatively synthesis gas or methane can be used; however, the sulfate reduction rates with methane are still extremely low. Heavy metals such as Cu, Zn, Cd, Pb, Ni and Fe can be removed from waste streams by precipitation with biogenic sulfide. Because of differences in solubility products the metals can be selectively precipitated. The insoluble metal sulfides formed can be recovered in order to be reused.