Denitrification in nonhomogeneous laboratory-scale aquifers: 4. Hydraulics, nitrogen chemistry, and microbiology in a single layer. Final report

A two-dimensional mathematical model for simulating the transport and fate of organic chemicals in a laboratory scale, single layer aquifer is presented. The aquifer can be nonhomogeneous and anisotropic with respect to its fluid flow properties. The physical model has open inlet and outlet ends and is bounded by impermeable walls on all sides. Fully penetrating injection and/or extraction wells can be placed anywhere in the flow field. The inlet and outlet boundaries have user prescribed hydraulic pressure fields. The steady state hydraulic pressure field is obtained first by using the two-dimensional Darcy flow law and the continuity equation. The chemical transport and fate equation is then solved in terms of user stipulated initial and boundary conditions. The model accounts for the major physical processes of storage, dispersion, and advection, and also can account for linear equilibrium sorption, first-order loss processes, microbial denitrification, irreversible sorption and/or dissolution into the organic phase, metabolism in the sorbed state, and first order loss in the sorbed state.