New developments in reactor and process technology for sulfate reduction.

Sulfate reduction has been regarded in the past as an unwanted process in anaerobic treatment of sulfate-rich wastewaters. Research efforts were primarily focused on H2S toxicity, competition between sulfidogenic and methanogenic microorganisms and suppression of sulfidogenesis. More recently, the potential sulfidogenesis for treating a wide range of wastestreams contaminated with oxidized sulfurous compounds and/or heavy metals was also appreciated. Heavy metals can be removed by the formation and subsequent precipitation of poorly soluble metal sulfides. Basically two approaches can be distinguished in wastewater treatment: passive treatment using low-cost technologies and active treatment in newly developed bioreactors. Both strategies are discussed.