초록 ▼

A method for treating a subsurface formation with a ferrous compound, to reduce a contaminant therein, involves introducing into the subsurface formation a ferrous compound in combination with sodium hydrosulfite in an amount sufficient to substantially prevent precipitation, during the introducing,

A method for treating a subsurface formation with a ferrous compound, to reduce a contaminant therein, involves introducing into the subsurface formation a ferrous compound in combination with sodium hydrosulfite in an amount sufficient to substantially prevent precipitation, during the introducing, of a major portion of the ferrous compound. The method was found to be useful in the reduction of hexavalent chromium to trivalent chromium at a Superfund site.

대표청구항 ▼

We claim: 1. A method of treating a subsurface formation with a ferrous compound to reduce a contaminant, present in a high pH aqueous phase in the subsurface formation or in ground water entering the subsurface formation, to a harmless substance, said method comprising introducing into the subsurf

We claim: 1. A method of treating a subsurface formation with a ferrous compound to reduce a contaminant, present in a high pH aqueous phase in the subsurface formation or in ground water entering the subsurface formation, to a harmless substance, said method comprising introducing into the subsurface formation said ferrous compound in combination with sodium hydrosulfite in an amount sufficient to prevent precipitation, during said introducing, of a major portion of said ferrous compound. 2. The method of claim 1 wherein said contaminant is hexavalent chromium. 3. The method of claim 2 wherein said subsurface formation is lake fill. 4. The method of claim 1 wherein said subsurface formation is lake fill. 5. The method of claim 1 wherein said ferrous compound is ferrous chloride or ferrous sulfate. 6. The method of claim 1 wherein said ferrous compound and said sodium hydrosulfite are introduced in an approximately 1:1 molar ratio. 7. The method of claim 1 wherein said subsurface formation is an acquifier formation. 8. The method of claim 1 wherein said subsurface formation is a structured zone formation. 9. The method of claim 1 wherein the high pH is greater than 11. 10. The method of claim 1 wherein the high pH is at least 9.8. 11. The method of claim 1 wherein the contaminant is hexavalent chromium and wherein the hexavalent chromium is reduced to trivalent chromium and precipitated as an amorphous CrxFe1-x(OH)3 solid. 12. The method of claim 1 wherein solids within the subsurface formation are covered with sorbed ferrous iron, thereby imparting the subsurface formation with a residual treatment capacity.