In-situ generation of oxygen-releasing metal peroxides
View Patent ↗A method for remediation of contaminants in soil and groundwater is disclosed. The method generates oxygen releasing solids in groundwater or soil by injecting an aqueous energetic oxidant solution containing free radicals, oxidative conditions can be created within or ahead of a contaminant plume. Some contaminants may be remediated directly by reaction with the free radicals. Additionally and more importantly, the free radicals create an oxidative condition whereby native or injected materials, especially metals, are converted to peroxides. These peroxides provide a long-term oxygen reservoir, releasing oxygen relatively slowly over time. The oxygen can enhance microbial metabolism to remediate contaminants, can react with contaminant metals either to form immobile precipitants or to mobilize other metals to permit remediation through leaching techniques. Various injection strategies for injecting the energetic oxidant solution are also disclosed.
1. A method for providing the in situ creation of a widespread, long-term source of oxygen in subsurface groundwater or soil, said method comprising the steps of:
a) determining the quantity of peroxidizable metal in the subsurface groundwater or soil of a selected site that is available for reacting to create metal peroxides;
b) creating an aqueous reagent solution containing energetic oxidizing free radicals; and,
c) injecting said solution into said groundwater or soil in an amount sufficient to convert said metals into solid metal peroxides whereby a long term source of oxygen is provided.
2. The method of claim 1 wherein said peroxidizable metals are selected from the group consisting of magnesium, calcium, and other alkaline earth metals.
3. The method of claim 1 wherein said aqueous reagent solution comprises superoxide or hydroxyl radicals.
4. The method of claim 1 wherein said aqueous reagent solution contains radicals selected from the group consisting of nitric oxide, permanganate, hydroxyl radicals, perchlorate, persulfate, and chloride.
5. The method of claim 1 including, after step (a) but before step (c) the steps of providing a metal solution which is suitable for injection into the soil or groundwater and injecting said metal solution into the soil or groundwater.
6. A method for providing the in situ creation of a widespread, long-term source of oxygen in subsurface ground water or soil comprising the steps of:
a) determining the quantity of peroxidizable metal in the subsurface groundwater or soil that is available for reacting to create metal peroxides at a selected site;
b) creating an aqueous reagent solution comprising additional peroxidizable metals;
c) creating another aqueous reagent solution comprising energetic oxidant free radicals;
d) injecting said solutions into the groundwater or soil in locations at the selected site that are spaced apart each from the other, said solutions being injected in quantities sufficient to react to form solid metal peroxides; and
converting said peroxidizable metals of steps a) and b) Into said solid metal peroxides at subsurface locations where said solutions mix.
7. The method of claim 6 wherein the peroxidizable metals are selected from the group consisting of calcium, magnesium, and other alkali earth metals.
8. The method of claim 6 wherein said energetic oxidant free radicals are selected from the group consisting of nitric oxide, permanganate, perchlotare, persulfate, and chloride radicals.
9. A method for in situ treatment of contaminants in groundwater or soil comprising the steps of:
a) determining the quantity of peroxidizable material in the groundwater or soil of a site selected for treatment;
b) providing precursor reagents, the mixture of which will produce an energetic oxidant solution containing free radicals;
c) injecting the precursor reagents separately into the soil or groundwater to be treated in an amount sufficient to create solid peroxide material in the soil from said peroxidizable material or groundwater, whereby the solid peroxidized material provides for the long-term release of oxygen sufficient to treat said contaminants.
10. The method of claim 9 wherein the injection step is performed by injecting the first of said reactants at a first site and the second reactant at a second site which is spaced apart from the first site whereby a subsurface reaction zone is initiated between said sites.