In Situ Aquifer Reclamation by Chemical Means: A Feasibility Study

Cleanup of ground water contaminated by organic chemicals that adsorb to aquifer solids may require decades if the water is pumped to the surface to be treated by conventional technologies. In situ treatment means treatment of the contaminant while it is still in the aquifer. It could conceivably take place at the rate at which the treatment can be transported to the contaminant. Although in situ biotic processes appear promising in many aquifer reclamation applications, chemical in situ reclamation using free-radical processes represents a complementary, and in some respects more general, method of destroying organic contaminants in aquifers. This feasibility study has demonstrated that chemical in situ aquifer reclamation can be feasible in at least some situations. In one experiment, 58 ppm (in the pore water) of benzene, used as the model contaminant, was 62% destroyed when the experiment was terminated at the end of two months. Reactive free radicals were generated from more stable water-soluble reagents which are pumped to the contamination region. The rate of generation of free radicals was not predictable from batch solution kinetic studies, but was accelerated, apparently due to the presence of promoter susbstances formed in the reaction of free radicals with soil material. The presence of 50 ppm alkalinity had no detrimental effect on the process.