Sulfaatinpelkistyksen Hyoedyntaeminen Happamien Kaivosvesien Kaesittelyssae. Opas Louhoskaesittelyn Naallintaan, ( In Situ Teatment of Acid Mine Dainage by Sulphate Reducing Bacteria. Guide to the Pit Lake Treatment)

摘要

Sulphate reducing bacteria (SRB) are a diverse group of anaerobic microrganisms that can under suitable conditions reduce sulphate to sulphide, following the reaction of sulphides and metal ions to produce relatively stable metal sulphides. Several different treatment options utilize sulphate-reducing microbial process in the treatment of acid mine drainage (AMD). One of these options include treatment method in which flooded open pits and mine shafts are used as large bioreactors to treat AMD. The idea is to stimulate bacterial growth and metabolism directly in the contaminated water body and to use the mine itself as a sedimentation basin for metal sulphide sludge formed by precipitation. In order to promote bacterial growth source of bacteria, organic carbon and nutrients is added into the open pit or mine shaft. This approach makes it possible to control the chemistry of waters discharging from the pits and shafts before their release into surrounding environment. In the optimal case an active anaerobic sulphate reducing population is formed to the bottom and walls of the pit and the pit begins to function like many natural anaerobic aqueous environments do. However, the startup of the microbiological activity takes some time, because the microbes require sufficient amount of organic material and nutrients and specific growth conditions in order to work properly. Depending on the quality of AMD, source of bacteria and substrate material, and characteristics of the mine, the startup of the sulphate reducing process in full-scale may require up to 2.3 years.