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Modeling transport and
biodegradation of BTX compounds in saturated sandy soil
Research Institute, King Fahd
Univ. Petrol. and Minerals,
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Abstract
Numerical
models have been developed using finite difference and orthogonal collocation
methods to simulate one dimensional transport with time-dependent pore water
velocity. The modeling process includes sorption given by linear isotherm and
biodegradation given by a variety of kinetics such as first-order, zero-order,
Monod, non-growth associated Monod (Michaelis-Menten),
Haldane and many other inhibitory and non-inhibitory kinetics. A number of
initial and boundary conditions such as Dirichlet's, Neuman's, mixed, decaying, etc. have been modeled. The
method of finite difference (for first order/zero order model
only) and the method of orthogonal collocation (for all kinetics models) have
been used to solve the governing transport equation. Numerical solutions have
been verified with existing analytical solutions for special cases. Three
models (first-order and/or zero-order, non growth associated Michaelis Menten, and Monod) have
been inverted using a Gauss-Marquardt-Levenberg
algorithm to assess the transport parameters. The models have been used to
simulate one dimensional transport of BTX compounds in a pilot scale sand tank
model. The data have been found to fit to all three kinetic models with
acceptable coefficient of determination (R2) and parameter values.
The high concentration data have been found to fit better to the Michaelis Menten and the Monod
models than the first order/zero order model.