Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
1993-11-03
2001-04-17
Cintins, Ivars (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S620000, C210S747300
Reexamination Certificate
active
06217767
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to the removal of contaminants from groundwater and/or wastewater. More specifically, the invention relates to a novel process for the removal of hydrocarbon contaminants from groundwater and/or wastewater by a novel vacuum sparging process wherein differential pressure is used to assist in the flow of a purging gas through the contaminated groundwater and/or wastewater in order to strip or volatilize the hydrocarbon contaminants therefrom.
RELATED ART
The discovery of groundwater contaminated by hydrocarbons has, on a national and world-wide scale become of great significance due to the high costs of restoration and to the large number of identified cases. Remedial technologies currently being utilized on a grand scale include groundwater extraction and treatment, in-situ bioremediation, vapor extraction (above water table) and chemical injection.
Groundwater extraction and treatment is probably the most commonly utilized approach. This process includes pumping contaminated groundwater from wells or trenches and facilitating above-ground treatment and discharge either to surface water, Publicly Owned Treatment Works or reinfiltration (exfiltration). Groundwater extraction is accomplished utilizing a wide variety of pump types, depending upon site-specific conditions. Treatment is usually afforded by (1) pressure sparging (tank aeration), (2) packed column air strippers, (3) bioreactors, (4) carbon filtration, or (5) a combination of the above methods. Tank aeration involves the addition of pressurized air to the treatment vessel through diffusers, etc. Packed column air strippers utilize counter-current air forced upward through a packed column or tower while contaminated water flows downwardly therethrough. Bioreactors are akin to most wastewater treatment plants where degrading organisms are artificially enhanced to proliferate and consume or break down organic compounds, and carbon filtration is utilized to remove organic constituents by adsorption.
In-situ bioremediation is often implemented on a site-specific suitability basis (i.e., where the hydrogeological environment allows for the proliferation of suitable hydrocarbon degrading microorganisms by either introducing nutrients or bacteria into the groundwater system or by monitoring the natural proliferation of biodegrading species). Air or oxygen is sometimes introduced into the system by pressure sparging or by the addition of oxygenating chemicals.
Vapor extraction is utilized in the removal of vapor-phase hydrocarbons above the water table using a vacuum. Chemical injection is usually utilized as an assistant to biodegradation through the direct injection of chemicals into groundwater or process tanks.
Specific prior art references of interest include
U.S. Pat. No. 4,923,125 to Bateson et al. which discloses a process for treating contaminated soil wherein hydrophobic materials are released in a liquid to interface with air bubbles and float to the top of a flotation cell. U.S. Pat. No. 4,017,120 to Carlson et al. discloses a process for the production of hot brines from liquid dominated geothermal wells by gas lifting. Also of note, U.S. Pat. No. 4,660,639 (Reissue 33,102) to Visser et al. discloses a vapor extraction process for vadose zone volatile compound removal.
DISCLOSURE OF THE INVENTION
In accordance with the present invention, applicant provides a process for removing hydrocarbon contaminants from groundwater and/or wastewater including the steps of subjecting the surface area of the groundwater and/or wastewater to at least a partial vacuum and then positioning at least one conduit into the groundwater and/or wastewater wherein the distal end is submerged therein and the proximal end is located above the groundwater and/or wastewater. A purging gas is introduced under at least atmospheric pressure into the proximal end of the conduit so that the gas will form bubbles as it flows from the distal end thereof wherein the bubbles serve to remove the hydrocarbon contaminants from the groundwater and/or wastewater as they travel upward to the surface area thereof. Finally, the contaminated gases are removed from the surface area of the groundwater and/or wastewater.
It is therefore the object of this invention to provide a novel process for the removal of semi-volatile and volatile hydrocarbon compounds from in-situ groundwater.
It is another object of the present invention to provide a novel process for the removal of semi-volatile and volatile hydrocarbon compounds from above-ground groundwater and/or wastewater treatment tanks.
It is still another object of the present invention to provide a novel process for the low cost removal of hydrocarbon contaminants from groundwater and/or wastewater located in groundwater wells, treatment trenches and above-ground treatment tanks by means of the novel application of existing and readily available equipment.
Some of the objects of the invention having been stated, other objects will become evident as the description proceeds when taken in connection with the accompanying drawings described hereinbelow.
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Cintins Ivars
Clark Environmental Services
Jenkins & Wilson, P.A.
Skovd Jennifer L.
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