Model for microbial degradation of nonpolar organic contaminants in a soil slurry reactor

An extended radial pore effective diffusion model is presented, describing the (microbial) decontamination of oil contaminated soil in a slurry. The aim of the model is to estimate the biodegradation rates of nonpolar contaminants in soil slurries. In the model, the soil is divided into three separate fractions, each of which contributes independently to the oil concentration in the slurry. The sand fraction is not inhibiting microbial degradation of the oil. The organic matter fraction limits the oil transport rate from the soil particles to the microorganisms. The clay fraction exhibits an extremely low transport rate for the nonpolar contaminants, about 1000 times lower than the organic matter fraction. The two types of clay used in this research showed comparable sorption coefficients. The model was tested on the decrease of hexachlorocyclohexane concentrations in two different types of soil. The diesel oil concentration in a sieve fraction of a contaminated soil, containing high amounts of clay and organic matter, could be modeled well with only one fitting parameter by using the previously measured sorption coefficients for hexadecane.