BIOTRANSFORMATION OF AROMATIC-HYDROCARBONS IN SUBSURFACE BIOFILMS

Bioremediation is an emerging in situ treatment technology for soil an d groundwater cleanup. Research in the past decade has made significan t progress toward understanding how to stimulate microbial growth in t he subsurface by optimizing the physical/chemical conditions. Recent l aboratory observations and field demonstrations indicate that bioremed iation can also be limited by mass transfer processes. In this paper, factors restricting microbial growth are reviewed, and the importance of bioavailability on the performance of in situ bioremediation is dis cussed by using aromatic hydrocarbons as model contaminants. Successfu l application of bioremediation relies upon an understanding of intera ctions among microorganisms, organic contaminants and soil/aquifer mat erials. Applications of biofilm kinetics toward this goal are addresse d. Model simulations and laboratory studies suggest that both low temp erature and slow desorption rate could greatly lengthen the time requi red for effective in situ bioremediation of aromatic hydrocarbons.