A SIMPLE METHOD TO STUDY THE EFFECTIVENESS OF BIOREMEDIATION AIDED, PUMP-AND-TREAT TECHNOLOGY FOR AQUIFERS CONTAMINATED BY NONAQUEOUS PHASELIQUIDS .2. MULTICOMPONENT SYSTEMS

Environmental contaminants are frequently encountered as mixtures of n on-aqueous phase liquids (NAPLs). The dissolution of organic mixtures from the aquifer has been examined with and without biodegradation, Va rious physical processes involved have been quantified based on the as sumptions that liquid-liquid and sorption equilibria are established a t the beginning of each flushing; oxygen required for biochemical oxid ation is completely consumed by the end of each flushing; and the rate of biochemical oxidation obeys the Monod kinetics for a multi-substra te system, characterized by an oxygen utilization factor. The mass fra ction of any component remaining in the aquifer, its aqueous concentra tion, and the composition of the NAPL have been obtained as functions of the number of flushings (volume of the flushing solution/volume of the aqueous-phase voids). The results of the simulation with the model demonstrate that highly soluble components of the NAPL are mainly rem oved by the pump-and-treat mechanism while the components of extremely Low solubility are unavailable to the microbes as substrates in a mul ti-component scenario. Bioremediation, however, transforms a significa nt proportion of the low solubility compounds after the more soluble c omponents have been removed from the aquifer. The results also demonst rate that the rate of removal of compounds is retarded by the inclusio n of a non-soluble component in the mixture.