BIOF&T allows real world modeling not available in similar packages. Model convection, dispersion, diffusion, adsorption, desorption, and microbial processes based on oxygen-limited, anaerobic, first-order, or Monod-type biodegradation kinetics as well as anaerobic or first-order sequential degradation involving multiple daughter species.

BIOF&T (2-D/3-D) is a three (two) dimensional finite element model for flow of water and multi-component aqueous phase transport in variably-saturated porous media. BIOF&T has capabilities to model contaminated sites that have complex heterogeneous and/or anisotropic hydrogeology. BIOF&T models variably-saturated fractured media or unfractured granular porous media based on a dual porosity approach.

The flow and transport in the unsaturated zone is modeled either in 1-D vertical or in 2-D planar or radial symmetric vertical sections or in full 3-D. The flow and dissolved phase transport in the saturated zone are modeled as 2-D areal or a 3-D phenomenon. BIOF&T allows uncoupled solution of the unsaturated and the saturated zones. During the solution of the unsaturated zone, the time series of the spatially-distributed contaminant effluent rate is computed and subsequently used to define loading to the groundwater. BIOF&T 3-D has options for coupled three-dimensional solutions of the unsaturated and saturated zones for complicated problems.

Two-dimensional rectangular or isoparametric quadrilateral or 3-D rectangular prism or isoparametric hexahedral elements are permissible to accurately model irregular domain and material boundaries. BIOF&T incorporates convection, dispersion, diffusion, adsorption, desorption and biodegradation based on oxygen limited, anaerobic, first-order, or Monod-type biodegradation kinetics as well as sequential anaerobic or first-order biodegradation involving multiple daughter products. Given the initial conditions, temporal and spatial variation in the source (i.e., nonaqueous phase liquid) is computed and updated internally by the model. Spatially-variable recharge rates accounting for different hydrogeologic conditions can be specified.

BIOF&T is accompanied by a Pre-processor, a Mesh Editor and a Post-processor. The Pre-processor and Mesh Editor can be used to create an input data file for BIOF&T. They include tools for: mesh generation; allocating heterogeneous and anisotropic soil properties; defining fixed head, flux, source/sink boundary conditions for flow; and fixed concentration, mixed type, and injection/extraction boundary conditions for multi-component transport; and allocating spatially variable recharge in the domain.

Required input for flow analyses consists of initial conditions, soil hydraulic properties, time integration parameters, boundary conditions and mesh parameters. The van Genuchten constitutive model is used to define the moisture retention properties for the unsaturated zone. For transport analyses, additional input data are the porous media dispersivities, fraction of the porous media as mobile phase (needed only for fractured media analysis), species solubility, biodecay parameters, diffusion coefficient, distribution coefficient, mass transfer coefficients (needed only for fractured media analysis).

The BIOF&T output file includes a list of the input parameters, initial and boundary conditions, and the mesh connectivity. It also includes pressure, water saturation, and velocity for each node and total volume of water versus time, recovery/injection rate for each sink/source location versus time. For transport simulations, the species concentration at each node, total mass of species in water and in the residual hydrocarbon phase are included at each printout interval. Flow and transport simulations can be performed in stages and BIOF&T creates an auxiliary file at the end of the simulated stage that can be used to define initial conditions for the next stage.

SYSTEM REQUIREMENTS

(1,500 nodes) Windows 95/98/2000/NT and 8 MB RAM. BIOF&T 3-D requires Windows95/98/2000/NT and 16 MB RAM.

This program can be purchased from Scientific Software Group. .