Microbial leaching utilizes the interactions between microorganisms and minerals. Today, the world production of about 25 % of the copper, 10 % of the uranium, 3 % of the cobalt and nickel, as well as 10 % of the gold are based on this technology. Mainly, sulfidic low-grade ores are bioleached. Extensive research for replacing conventional pyrometallurgical techniques with bioleaching processes is currently performed. Besides from ores, metals such as copper can also be won from electronic industry waste by specific bioleaching processes. Bioleaching can also be employed for the treatment of the pollutions caused by mining activities, such as waste heaps and tailings. Thus, important metals otherwise lost can again be filled into the cycle of matter. On the other hand, uncontrolled bioleaching activities at mining sites and waste heaps is responsible for an environmental problem known as Acid Rock Drainage (ARD), which could result in an extensive heavy metal contamination of soil and groundwater. Furthermore, ARD is not only related to metal winning but also to coal mining activities. Coal contains up to several percent sulfur which is dominantly in the form of pyrite or marcasite (FeS2). Due to uncontrolled activity of leaching bacteria mining lakes can develop having pH values around 2 and high concentrations of heavy metals. An example for such activities are the acidic lakes in the eastern part of Germany which formed after flooding abandoned open pit lignite mines.

Services

• Determination and characterization of the relevant leaching bacteria by classical and molecular microbiological methods
• Biochemistry, physiology and systematics of relevant leaching bacteria
• Collection of reference bacterial strains isolated worldwide from leaching sites
• Planning and optimization of bioleaching processes
• Activity measurement by microcalorimetry
• Development of strategies for the prevention of undesirable bioleaching activity

Biofilms could accelerate the corrosion of mineral, metallic, and polymeric materials (biocorrosion). It is estimated that annual corrosion damages, calculated as maintenance costs, reach about 6000 million € in Germany and that 10-20 % of these damages were microbially influenced. For getting the hang of these mainly biofilm-related problems, we perform detailed and systematic investigations on the corrosion mechanisms and the involved microorganisms, as well as on the resistance behavior of on principle suitable materials (behavior of microorganisms at interfaces, biotic-abiotic interactions at interfaces, material tests).

Services

• Detection of microorganisms responsible for corrosion processes
• Activity measurements by microcalorimetry
• Characterization of microbial groups relevant for corrosion processes
• Design and realization of test plants or use of existing plants (bioreactor, Mini-Plant) for studying corrosion mechanisms
• Development of measures for the prevention and rehabilitation of biocorrosion