Development of a transport model for the microbial degradation of polycyclic aromatic hydrocarbons in a saturated porous medium.

Abstract

A mathematical model for first order reaction rate under isothermal condition was developed for predicting the diffusivity and transport rate of anthracene and pyrene during biodegradation using two microbial strains (corynebacteria spp and pseudomonas putida) in a heterogeneous porous medium. The formulation followed the conservation laws and employed the concepts from the correlations of Fick’s law of diffusion, Malthus equation and Monod kinetics. Experimental results on reaction rate constant, transport rate for the contaminant solutes as well as the saturation constant, yield coefficient and maximum specific growth rate of the microbial strains were used to characterize the biodegradation process. The results showed that corynebacteria spp was more effective for the degradation of anthracene and pseudomonas putida more suitable for  pyrene utilization. Studies further showed a decrease in the effective diffusivity with increasing degree of penetration, decreasing solute concentration and increasing microbial mass, and affirm that the interactions between microbial species in a pure culture are significant for the prediction of biodegradation kinetics. In the light of limitations arising from the expensive and cumbersome nature of experimental studies, the developed model has been demonstrated to be adequate in effectively providing insight into an appropriate methodology of classifying microbes in order of their preference for contaminant solutes.