A forward particle tracking Eulerian Lagrangian Localized Adjoint Method for multicomponent reactive transport modelling of biodegradation

摘要

A solution of the contaminant transport equation obtained with the forward particle tracking Eulerian Lagrangian Localised Adjoint Method (ELLAM) is coupled via Strang operator splitting to a modified Monod microbial kinetics model for simulating biodegradation. The model includes substrate, oxygen, and biomass concentrations. The reaction equations are solved using a predictor corrector algorithm with adaptive time stepping and adjustment of time step size near the inflow boundary. The method is benchmarked against the direct ELLAM solution of Wang et al. (1995) for the test problem of Celia et al. (1989). The split operator approach is shown to be competitive with the direct solution for simple test problems and is expected to have better performance for more complex multi-component systems. Nonlinear regression using a shuffled complex evolution algorithm is then used to fit the transport and biodegradation model to column experiment data. A Metropolis algorithm is used for uncertainty analysis. These inverse methods were employed in a case study of aniline substrate depletion data from laboratory scale column experiments using pristine aquifer material from CFB Borden, Ontario as a microbial population source under aerobic conditions. Results show that the transport and biodegradation model parameters were uniquely identified when fitted to the aniline and oxygen concentration data from the column experiment.