Modeling Water Quality of AMD along the Flow Path

Abstract

The water balance is severely disturbed in post-mining landscapes like Lusatia/Germany. Mine waters (amd) enter the environment and spread in groundwater and surface waters. Groundwater containing high amounts of pyrite weathering products flows into receiving waters due to lignite mining for several years. The Chair of Wassertechnik & Siedlungswasserbau at the Brandenburg University of Technology Cottbus-Senftenberg/Germany has developed a subsurface rehabilitation method using microbial sulfate reduction over the past 25 years. A continuation of the research is unlikely. This paper has presented some research results on the behavior of groundwater acidified by mining. The acidity in the surface and groundwater is specified via the negative neutralization potential. The dominant reactions in AMD genesis and migration through the aquifer are evaluated about their acidity formation or their buffering behavior. The behavior of AMD can be summarized in a simplified way in the acidity-sulfate diagram. A flow section model (PhreeqC2) was developed and parameterized based on this. This can describe the migration of quality changes in the groundwater/aquifer system. The aquifer passage is reduced to a filtration process, analogous to water treatment. The processes occurring at compartment transitions (dump-lake-aquifer-...) can be modeled from anoxic to oxic. A first case study produces the infiltration of neutralized opencast mining lake water into an aquifer influenced by mining. Measured absorption effects during a microbiological sulfate reduction are interpreted in the second case study with an extended flow path model. The results presented are recommended for use. A comprehensive summary of the results obtained over 25 years of research is being prepared.