In times of dramatically increase of population, resources that are non- regenerative are depleted. A considerable reduction of mining for raw materials is not feasable in the face of a continuously increasing demand. Additionally, the dumping of heavy metal polluted solids is more and more problematic, because the use in agriculture or building industry often is not possible. Bioleaching, known from the leaching of ores, is used as alternative concept for remediation, for heavy metal decrease and fixation in the ash.
Originally designed for ashes from sewage sludge incineration, this process can be transferred to other solids. The focus lies on possibilities for heavy metal decrease as well as fixation in the ash, to avoid entry into the groundwater and to regain the metals as resources. The bioleaching bacteria of the Acidithiobacillus species oxidize metal sulfides, dissolving metal ions. At the same time, bacteria produce sulfuric acid, bringing heavy metals soluble in acid to dissolve.
For the remediation of solids with the bioleaching process no standard procedure exists, moreover the general requirements for the applicability of the process are not clarified. For every material that has to be remediated, the process has to be optimized and adapted.
- Economical leaching of low-concentrated or impure ores
- Leaching at low temperatures and atmospheric pressure
- No addition of expensive chemicals due to biogenic production of sulfuric acid
- Easy handling
- No CO2- emissions (less energy input, microorganisms fix CO2)2)