Abstract
Biotechnological sulfate reduction is a core process in the desulfurization of sulfate-rich waste streams. Sulfate-rich wastewaters from coal-burning power plants, mining, and metallurgical activities represent a special case because these wastewaters do not contain electron donors for sulfate reduction. To circumvent this problem, ethanol or hydrogen is added. Implementation of biological sulfate reduction to treat such industrial effluents depends largely on the economic feasibility of the process and most of the cost is associated to the supply of electron donor. The direct use of methane as electron donor is economically more advantageous. Currently, the main challenge is the development of a sludge or biofilm system that is capable of catalyzing the anaerobic oxidation of methane coupled to sulfate reduction at important rates. This microbial process has been observed in marine ecosystems. The article provides an overview of what is known about the process followed by an analysis of laboratory experiments for its application to treat sulfate-rich streams lacking electron donors. Encouraging results have been obtained using membrane-based bioreactors and bottlenecks have been identified.