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MULTIPHASE CONTAMINANT TRANSPORT, REACTION AND BIODEGRADATIONProject members have developed two reactive transport models: BIOMOC and RATEQ. BIOMOC simulates 2D transport and biodegradation of organic contaminants in groundwater. The BIOMOC model is significant as a tool for understanding and quantifying the role of biodegradation in groundwater remediation. Nationwide, all petroleum hydrocarbon sites and about 30% of chlorinated solvent sites are undergoing some degree of intrinsic bioremediation. BIOMOC can be used to evaluate whether the intrinsic bioremediation processes can be sustained over time and to estimate whether the contaminant plume is likely to pose a risk to drinking water supplies. The code has been documented and is currently being used to model sites in Aberdeen Proving Ground, MD. Ft. Wainwright, Alaska. Niagara, NY, and Norman OK. RATEQ (rate and equilibrium controlled solute transport) is a flexible model for simulating transport of multiple reacting chemical species. It can be applied to 1D or 2D problems with an unlimited number of solutes undergoing either rate or equilibrium controlled reactions. Microbial growth, decay, and transformation reactions are included as a subset of rate-controlled reactions. Transport can be simulated using a simple finite difference method or an oscillation free total variation diminishing method. The RATEQ code represents two significant advances: the geochemical solver can solve systems with very large equilibrium constants and it can solve chemical kinetics simultaneously with the chemical equilibria. The latter capability allows simulation of inorganic reactions together with degradation reactions that occur during intrinsic bioremediation. The effect of abiotic inorganic reactions on intrinsic bioremediation rates has been recognized as an important problem for some time, and RATEQ represents one of the first modeling tools capable of simulating both reaction type. The URL for this page is:
http://wwwrcamnl.usgs.gov/transport.html |