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De-acidification of flooded lignite mining lakes by controlled eutrophication microcosms experiments
(2001)
Control of the remediation of anoxic AMD groundwater by sulphate reduction in a subsoil reactor
(2017)
Groundwater containing high amounts of products of pyrite weathering flows into receiving waters in consequence of lignite mining for a number of years. Iron hydroxides causing turbidity and silting will strongly affect the river Spree for many decades. In addition to liming acidic surface waters and the conventional treating of mine waters, microbial sulphate reduction of the inflowing anoxic AMD groundwater is tested for long-term remediation.
During a pilot project at the location ‘Ruhlmühle’ in north Saxony since end of 2014 glycerin as a carbon source and nutrient solutions of N and P are infiltrated in an anoxic AMD groundwater stream by lances ([1]). Planning and operation were carried out based on a model. The complex reaction mechanisms in the aquifer were formulated using phreeqc2. They were applied to the flow path from the infiltration to the measuring points as a mixed cell model. Based on literature research as well as laboratory experiments and pilot tests ([2], [3]), the biochemistry of the sulphate reduction was drafted as an extensive reaction term refined by adaption to experimental results later on.
To describe the sorption processes on the solid matrix of the aquifer, the surface ‘Sandw_OH’ had to be defined and parameterized. The behavior of metabolites and humic substances could only be considered with the aid of new reaction models. On the basis of intensive preliminary investigations, the mixed cell model developed for the pilot sites can be applied to other glacial aquifers. Moreover, it was possible to elucidate numerous side reactions and to describe them in the model. Ultimately, the process of sulphate reduction is available for the treatment of groundwater containing high amounts of products of pyrite weathering. It can be applied at the source as well as on the flow path. Design and control of the variety of overlapping processes is only possible by means of the developed model approaches.