A Model of in Situ Bioremediation That Includes the Effect of Rate- Limited Sorption and Bioavailability

In situ bioremediation is a groundwater and soil remediation technology that makes use of indigenous or introduced microorganisms to degrade contaminants in the subsurface. One factor affecting the feasibility of in situ bioremediation is the availability of the contaminant to the microorganisms. It is typically assumed that the contaminant is only available for biodegradation in the aqueous phase. However, many organic contaminants of interest are sorbed to soil in the subsurface, and the sorbed contaminant is presumably unavailable for bioremediation. If bioremediation is attempted, the rate of desorption of contaminant from the sorbed phase is a factor in determining the availability of the contaminant to the degrading microorganisms and hence, the efficacy of the remediation. In this work, a transport model is presented that accounts for both biodegradation and desorption kinetics. The model is run using realistic parameter values obtained from a recent field evaluation of in situ aerobic cometabolic bioremediation at Edwards AFB, to demonstrate the potential impact of rate-limited sorption on bioremediation efficacy. The model allows remediation managers to better understand the impact of the in situ bioremediation technology on the fate and transport of contaminants, ultimately helping these managers design and implement solutions to contamination problems.