‘Soft’ remediation strategies: examples for activation of microbiological self-cleaning potencies in contaminated water, sediment and soil

For over a century, the regions of Saxony and Saxony-Anhalt in the eastern part of Germany have been the most important producers of lignite in the world. Before its collapse in 1989, the former East German Republic was mining more than 300 million tons of lignite per year — over one-quarter of the total world production from a country smaller in area than the state of New York. Altogether, 33 open-cast mining areas were exhausted, resulting in an almost unimaginable destruction of agricultural and recreation areas and of villages. Satellite photographs show that a belt of about 90 × 30 km was strongly affected. The groundwater level was artificially lowered by more than 30 m in some places. After the mining finished, pyrite oxidation caused water acidification of the flooded areas, preventing any application of the lakes which were formed.