Modeling Bioremediation of Acid Mine Drainage in Permeable Reactive Barriers

Biological, sulfate reducing permeable reactive barriers (PRBs) containing decomposable solid organic substrates can be used for in-situ bioremediation of ground water impacted by acid mine drainage (AMD). A new mathematical model for bioremediation of AMD in these PRB systems is presented. The model combines the primary processes of (i) decomposition of polysaccharides in solid (particulate) organic materials, (ii) sulfate reduction based on lactate, (iii) precipitation of insoluble heavy-metal sulfides, (iv) partial volatilization of H₂S to the gas phase, and (v) reversible dissolution-precipitation of calcite (CaCO_3(s)) and metal carbonates. Based on comparisons of model simulations with experimental data, the performance of these sulfate reducing systems is shown to be affected critically by the availability and decomposition kinetics of polysaccharides within the solid organic materials provided to the system.