Enhanced In‐Situ Biodegradation and Aquifer Permeability Reduction

Abstract

A model describing the enhanced in‐situ biodegradation of an organic substrate in ground water is presented. This model simulates the transport and aerobic utilization of substrate and oxygen; the transport and growth of biomass dispersed in the water phase and in the biofilm; changes in porous‐media properties as a result of biofilm growth; and biofilm shearing and filtration. The model is applied to a recharge well to simulate the injection of an electron donor (substrate) and electron acceptor (oxygen) into an aquifer. Results show that a porous medium having a high porosity, wide range of pore sizes, and a small maximum pore radius is most susceptible to biofouling; and alternately pulsing the electron donor and acceptor reduces the biofouling propensity. The model is also applied to a hypothetical aquifer to simulate the process of bioremediation. Results show that increasing the oxygen concentration in the injection water, increasing the well‐pumping rate, and introducing oxygen through multiple injection wells all result in improved levels of bioremediation without causing excessive biofouling.