Modeling and simulation of in situ bioremediation for TCE-contaminated groundwater through methane injection in Kimitsu city, Japan

A one-dimensional model was developed for simulating the in situ bioremediation process in which trichloroethylene (TCE) in groundwater was transformed cometabolically by methanotrophs. The model includes basic processes such as advection, dispersion, and equilibrium sorption of methane, dissolved oxygen, methanotrophs, and TCE. Monod kinetics with a modified competitive inhibition term between methane and TCE, cell inactivation by product toxicity from TCE transformation, and deactivation of the enzyme in the absence of methane were also incorporated into this model. Simulation results were compared with data from a pilot biostimulation test performed at the Kururi site in Japan in 1998. The calibrated model provided good matches to observed changes of the chemical and the most-probable numbers of methanotrophs at the two monitoring wells for the 180 day test. Spatial distribution of the variables and the TCE degradation ratio were also evaluated using the calibrated model.