A benchmark for microbially mediated chromium reduction under denitrifying conditions in a biostimulation column experiment

作者：Molins Sergi^*; Greskowiak Janek; Wanner Christoph; Mayer K Ulrich

来源：Computational Geosciences, 2015, 19(3): 479-496.

DOI：10.1007/s10596-014-9432-0

• Reactive transport modeling
• Microbially mediated reduction
• Denitrification
• Chromium reduction
• Biomass
• Benchmark

Bioremediation efforts in aquifers contaminated with redox-sensitive contaminants often rely on in situ reductive immobilization. The bioremediation treatment usually involves injection of organic carbon into the subsurface (e.g., acetate) to stimulate the growth of indigenous bacteria that mediate the relevant redox processes that immobilize the target contaminant. Batch and flow-through column experimental studies are conducted to elucidate reaction networks associated with specific electron acceptor pathways and/or specific bacterial isolates. The proposed benchmark involves the simulation of microbially mediated chromium reduction under denitrifying conditions in biostimulated batch and flow-through column experiments. Simulated reactive processes include multicomponent aqueous complexation, kinetically controlled mineral precipitation and dissolution, biologically mediated reactions, and biomass growth and decay. The focus of the benchmark problem set is on the simulation of microbially mediated redox reactions with the explicit inclusion of the microbial community dynamics and the impacts on reaction rates. Rate expressions for microbially mediated redox reactions include kinetic limitations (Monod and inhibition terms) as well as thermodynamic limitations. Both catabolic (energy) and anabolic pathways (biomass growth) are considered in the microbially mediated reactions. Microbial biomass is assumed to be bound to the sediment (non-planktonic). Any reactive transport model used to reproduce results of this benchmark problem must be capable of simulating multicomponent aqueous complexation, kinetically controlled mineral precipitation and dissolution and kinetically controlled aqueous reactions. Though convenient, it is not necessary to allow for specific stoichiometric relationships for catabolic and anabolic pathways; only the overall reaction stoichiometry is used. Rate expressions for microbially mediated reaction must include a rate constant, the biomass concentration, and a number of Monod and inhibition terms. To ensure that the results presented in this paper were the correct solutions to the problems posed, the general-purpose reactive transport codes CrunchFlow, PHT3D, ToughReact, and MIN3P were used to perform the simulations. In general, results obtained with all codes show excellent agreement.

• 出版日期2015-6