Analysis of biodegradation and bacterial transport: Comparison of models with kinetic and equilibrium bacterial adsorption

An advection/dispersion/sorption model incorporating Monod kinetics (modified to describe bacterial growth near threshold concentrations of the contaminant) was used to analyze breakthrough curve and concentration profile data from soil column experiments previously reported for degradation of 1,2-dichlorobenzene by Pseudomonas P51. Two models for bacterial sorption in the column were compared: one assumed an equilibrium process and the other used first-order kinetics for adsorption and desorption. Numerical solutions of both models using reasonable parameter values represented the column concentration profile data well. The two adsorption models yielded qualitatively and quantitatively similar results for contaminant concentration data. However, significant differences in bacteria distributions and breakthrough curves were predicted from the two adsorption models. These are important considerations for distinguishing between various models of bacterial migration for field-scale applications.