Microbial activity in the schwertmannite formed in a mine-water treatment plant

摘要

In a pilot plant at the open pit Nochten (Lusatia, East Germany) acid-, iron-and sulfate rich mine waters are treated biotechnologically. The immobilization of iron is caused by microbial iron oxidation with the subsequent precipitation of the iron ( III) -oxyhydroxysulfate schwertmannite. To determine, if a recirculation of schwertmannite sludge can stabilize and optimize the oxidation process the cell number, activity and diversity of the bacterial community in fresh and aging schwertmannite was analyzed. In schwertmannite on carrier material the total cell number showed only a slight decrease with increasing depth of the mineral layer. The rate of living cells, as determined with a LIVE/DEAD Kit, decreased significantly with an increasing depth of schwertmannite layer. The microbial community, which was investigated using FISH and T-RFLP, independent of the depth of mineral layer was dominated by iron oxidizing bacteria belonging to "Ferrovum myxofaciens" or to Gallionella relatives. The number of active cells in aging schwertmannites was almost constant over several weeks.