DEVELOPMENT OF AN INJECTION SYSTEM FOR IN-SITU CATALYZED PEROXIDE REMEDIATION OF CONTAMINATED SOIL

In situ chemical oxidations have the potential for rapidly treating soils contaminated with toxic and persistent organic wastes. One mechanism for introducing strong oxidants into contaminated soils is the catalyzed decomposition of hydrogen peroxide (H2O2) to form hydroxyl radical (OH.), commonly known as Fenton's reagent. The res-arch presented in this paper investigated the injection of H2O2 at depth for treating sell. A scale model injection system was designed and constructed to deliver the H2O2 at depth. The tests were conducted in a polyethylene test tank. A natural sand from southeastern Washington state was placed in the tank under controlled density conditions and saturated with nitrobenzene, a documented hydroxyl radical probe. H2O2 was injected at a controlled flow rate through a Teflon rotary injection system. Bottom up injection was used for all tests. Pore fluid samples were extracted using thirty in-place glass sampling tubes placed at various depths and distances from the injection axis. Concentrations of nitrobenzene and H2O2 were measured to evaluate the influence of flow rate and H2O2 concentration on the effectiveness of the in situ delivery system.