Engineered in situ anaerobic reactive zones
First Claim
1. A method for removing contaminants dissolved in groundwater, said method comprising the steps of:
- providing at least one injection well extending from the ground surface to a contaminated saturated zone;
supplying carbohydrates and sulfates to said at least one injection well such that said carbohydrates and sulfates are introduced into said contaminated saturated zone, whereby microorganisms in said contaminated saturated zone metabolize said carbohydrates creating sulfate reducing and methanogenic conditions; and
maintaining said sulfate reducing and methanogenic conditions for a sufficient period of time such that chlorinated hydrocarbons present in said contaminated saturated zone are reduced to ethene.
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Accused Products
Abstract
An in situ method and system for reductive dechlorination, the precipitation of chromium, the precipitation of heavy metals, and microbial denitrification. The invention comprises the formation of in situ anaerobic reactive zones to precipitate and filter out dissolved heavy metals as metallic sulfides, to degrade nitrate to nitrogen gas, to reduce chlorinated hydrocarbons to ethene, and to precipitate and filter out chromium. The invention is comprised of an injection well or wells that extend into a contaminated saturated zone. A conduit located within the injection well conveys carbohydrates and sulfates to the contaminated saturated zone. Microbes digest the carbohydrates to produce sulfate reducing and methanogenic conditions within the reactive zone that include a dissolved oxygen level less than about 0.5 mg/l, a redox potential less than about -250 mv, and a dissolved organic carbon to contaminant ratio of greater than about 50:1. These biogeochemical conditions lead to the reduction of PCE to TCE to DCE to VC and eventually to ethene. These biogeochemical conditions also lead to the precipitation of heavy metals, the precipitation of chromium, and microbial denitrification.
83 Citations
31 Claims
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1. A method for removing contaminants dissolved in groundwater, said method comprising the steps of:
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providing at least one injection well extending from the ground surface to a contaminated saturated zone; supplying carbohydrates and sulfates to said at least one injection well such that said carbohydrates and sulfates are introduced into said contaminated saturated zone, whereby microorganisms in said contaminated saturated zone metabolize said carbohydrates creating sulfate reducing and methanogenic conditions; and maintaining said sulfate reducing and methanogenic conditions for a sufficient period of time such that chlorinated hydrocarbons present in said contaminated saturated zone are reduced to ethene. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for removing contaminants dissolved in groundwater, said method comprising the steps of:
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providing an injection well from the ground surface to a contaminated saturated zone; and supplying carbohydrates and sulfates to said injection well such that said carbohydrates and sulfates are introduced into said contaminated saturated zone; wherein microorganisms in said contaminated saturated zone metabolize said carbohydrates creating anaerobic conditions which lead to the reduction of hexavalent chromium or trivalent chromium and eventually the precipitation of chromic hydroxide. - View Dependent Claims (21)
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22. A method for removing contaminants dissolved in groundwater, said method comprising the steps of:
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providing an injection well from the ground surface to a contaminated saturated zone; and supplying carbohydrates and sulfates to said injection well such that said carbohydrates and sulfates are introduced into said contaminated saturated zone; wherein microorganisms in said contaminated saturated zone metabolize said carbohydrates creating anaerobic conditions which lead to the precipitation of metal compounds. - View Dependent Claims (23)
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24. A method for removing contaminants dissolved in groundwater, said method comprising the steps of:
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providing an injection well from the ground surface to a contaminated saturated zone; and supplying carbohydrates and sulfates to said injection well such that said carbohydrates and sulfates are introduced into said contaminated saturated zone; wherein microorganisms in said contaminated saturated zone are catalysts for the creation of anaerobic conditions which lead to the reduction of hexavalent chromium or trivalent chromium and eventually the precipitation of chromic hydroxide. - View Dependent Claims (25)
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26. A method for removing contaminants dissolved in groundwater, said method comprising the steps of:
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providing an injection well from the ground surface to a contaminated saturated zone; and supplying carbohydrates and sulfates to said injection well such that said carbohydrates and sulfates are introduced into said contaminated saturated zone; wherein microorganisms in said contaminated saturated zone are catalysts for the creation of anaerobic conditions which lead to the precipitation of metal compounds. - View Dependent Claims (27)
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28. A method for removing contaminants dissolved in groundwater, said method comprising the steps of:
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providing an injection well from the ground surface to a contaminated saturated zone; and supplying carbohydrates and sulfates to said injection well such that said carbohydrates and sulfates are introduced into said contaminated saturated zone; wherein microorganisms in said contaminated saturated zone are adapted to metabolize said carbohydrates and said sulfates to produce sulfide ions, said microorganisms thereby serving as catalysts for the reduction of hexavalent chromium or trivalent chromium and eventually the precipitation of chromic hydroxide. - View Dependent Claims (29)
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30. A method for removing contaminants dissolved in groundwater, said method comprising the steps of:
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providing an injection well from the ground surface to a contaminated saturated zone; and supplying carbohydrates and sulfates to said injection well such that said carbohydrates and sulfates are introduced into said contaminated saturated zone; wherein microorganisms in said contaminated saturated zone are adapted to metabolize said carbohydrates and said sulfates to produce sulfide ions, said microorganisms thereby serving as catalysts for the precipitation of metal compounds. - View Dependent Claims (31)
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Specification