Abstract: The reduction of halogenated organic compounds with an iron powder can be markedly accelerated to realize an enhanced reaction rate by the combined use of a reducing substance that is water-soluble and which exhibits weak acidity in water. The reducing substance such as sodium hydrogensulfite may be injected into the ground simultaneously with the iron powder or it may be preliminarily added to the contamination source via a different route than the iron powder which is subsequently injected. An amount of water containing 100 ppm of trichloroethylene (TCE) as a halogenated organic compound was provide; 500 ppm of sodium hydrogensulfite was added and 6,000 ppm of an iron powder was subsequently added; the time profile of the TCE concentration in the mixture was measured; as shown in FIG. 1, the TCE concentration decreased rapidly with the lapse of time and more than 90% of TCE was reduced in 8 days.

Abstract: A method for the in-situ remediation of contaminants including soluble metals more noble than iron and halogenated hydrocarbons that are present in groundwater, absorbed to soil, and exist in the free product state in a soil volume. An inert pressurized gas in combination with an atomized iron powder-water slurry is used to inject pre-determined quantities of reactive zero valent iron powder relative to the quantity of contaminants present in the soil for obtaining preselected rates of remediation with minimum quantities of iron powder and with reaction products within a preferred acidic pH range. Features, such as particle surface area and carbon content, are identified that enhance the reactivity of the iron powder.