Effective Porosity of Geologic Materials: First Annual Report

published or submitted for publicationis peer reviewedOpe

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.Hazardous Waste Research and Information Center ; Project Number HWR86-011published or submitted for publicationis peer reviewe

Treatability of Contaminated Ground Water and Aquifer Solids at 'Town Gas" Sites, Using Photolytic Ozonation and Chemical In Situ Reclamation

The feasibility of cleaning up contaminated ground water and aquifer solids from so-called "town gas" sites using photolytic ozonation and chemical in situ aquifer reclamation (CISR) techniques was investigated in the laboratory. At the actual site, coal was thermally oxidized to produce methane for municipal distribution. The degradation left a coal tar which, if released into the ground,could contaminate ground water and aquifer solids with a number of organic substances, including aromatic hydrocarbons such as benzene, toluene, xylene (BTX) , and polynuclear aromatic hydrocarbons (PAHs) at environmentally significant concentrations. Photolytic ozonation was used to destroy BTX and PAHs in ground-water samples taken from the Taylorville "town gas" site, using a stirred- tank reactor in the laboratory. Ozonation was found to be as effective as ozone/UV for this treatment. This is often seen in natural waters, and it is thought to be due to the presence of natural "promoters" for the free-radical reactions that are largely responsible for the destruction of organic compounds during treatment. Estimated treatment costs were $4.05 per thousand gallons (Kgal) for destruction of BTX and PAHs by ozonation, and$2.57 per Kgal if the BTX was removed by air stripping prior to ozone treatment. A chemical in situ treatment method using persulfate as a source of free radicals destroyed organic contaminants that were adsorbed to the aquifer solids. PAHs were reduced by 34 percent after 12 days of treatment and by 52 percent after 40 days. Preliminary evidence suggests that mobilization of contaminants by?? oxidation of the natural and/or adsorbed organic matter associated with the solids may be important.Hazardous Waste Research and Information Center ; Project Number 87-039published or submitted for publicationis peer reviewe