Biological recovery of metals, sulfur and water in the mining and metallurgical industry

Metals of particular interest in acid mine drainage and industrial wastewaters include copper, zinc, cadmium, arsenic, manganese, aluminum, lead, nickel, silver, mercury, chromium, uranium and iron, in a concentration that can range from 106 to 102 g/l. The composition of such wastewater reflects the particular combination of heavy metals and production process. Presently, removal by precipitation as metal hydroxide is the most widely used treatment method for water contaminated with heavy metals. This is because of the simplicity and the low costs of this method. For the same reasons, sulfate removal is mostly accomplished by precipitation with Ca2+, added as lime. However, more stringent legislation in future and an increasing scarcity of resources creates a need for heavy metal and sulfate removal technologies with a better performance. Thus, treatment processes should aim to recover valuable metals and other possible resources from waste streams such as sulfur compounds and process water. The biological reduction of sulfate to sulfide is catalysed by bacteria