Method for remediation of aquifers

Abstract

A method for remediating aquifers and groundwater contaminated, for example, by toxic halogenated organic compounds, certain inorganic compounds, and oxidized heavy metals and radionuclides, using the introduction of an innocuous oil, preferably an edible, food grade oil such as soybean oil, formulated into a microemulsion preferably by mixing with a natural food-grade emulsifier (such as lecithin) and water.

Description

[0001]NOTICE: More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,398,960. The reissue applications are Ser. No. 10 / 862,126 and the present application, which is a continuation of reissue application Ser. No. 10 / 862,126.GOVERNMENT LICENSE RIGHTS[0002]The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of contract F41624-99-C-8033 awarded by the United States Air Force Material Command.BACKGROUND OF THE INVENTION[0003]1. Field of the Invention[0004]This invention relates to the remediation of contaminated groundwater, and in particular, relates to a remediation method utilizing a microemulsion of an innocuous oil.[0005]2. Description of the Related Art[0006]There are numerous techniques employed for the remediation of contaminated groundwater in aquifers. The mechanisms for cleanup may be physical, chemical or bi...

AI Technical Summary

Benefits of technology

[0028]The invention herein is a method for remediating aquifers and groundwater contaminated, for example, by toxic halogenated organic compounds, certain halogenated inorganic compounds, and oxidized heavy metals and radionuclides, using the introduction of an innocuous oil, preferably an edible, food-grade oil, preferably formulated into a microemulsion by mixing with one or more natural food-grade emulsifiers (such as lecithin) and water. The invention provides a specific, time-release method of bioremediation. Pretreatment of the aquifer increases mobility of the emulsion through the aquifer.

Problems solved by technology

There is, however, significant capital expense associated with the installation of the required tanks, pumps, mixers, injection and pumping wells and process controls required to continuously feed a soluble easily degradable substrate.

Operation and maintenance costs can be high because of the frequent clogging of injection wells and the labor required for extensive monitoring and process control.

Most previous in situ bioremediation approaches have also relied on the injection of oxygen or oxygen-containing chemicals into the aquifer to provide electron acceptors to enhance aerobic biodegradation processes, however, this approach is not applicable to chlorinated solvents and other oxidized compounds.

When dense non-aqueous phase liquids such as halogenated aliphatic organic solvents are present or contaminants are present in lower permeable zones, dissolution rates are slow and a long time is required for aquifer cleanup.

Under these conditions high operation and maintenance costs are a major problem.

However contaminated groundwater often bypasses around these barriers unless they are constructed to completely enclose the contamination source.

The technology works well but is very expensive to construct.

Pump-and-treat technologies and funnel and gate barriers are not conducive to broad site cleanup.

These are interceptor technologies; there are no cost-effective technologies that address the entirety of the plume in situ.

Full-scale applications have been limited to treatment of wastewaters generated from handling rocket propellants in industrial situations.

Although dithionite has also been injected into wells to react with contaminants and precipitate in place, use of dithionite is less attractive due to its toxicity and cost.

The results of this study were that lactate could effectively promote anaerobic dehalogenation of the chlorinated solvents to non-toxic end products, but lactate addition resulted in biofouling of subsurface equipment.

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