Liquid purification or separation – Structural installation – Geographic
Reexamination Certificate
1998-11-23
2001-10-23
Simmons, David A. (Department: 1724)
Liquid purification or separation
Structural installation
Geographic
C210S192000, C210S198100, C210S205000, C405S128350
Reexamination Certificate
active
06306296
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention (Technical Field)
The present invention relates to sparging apparatuses and methods of in situ groundwater remediation for removal of dissolved chlorinated hydrocarbons and dissolved hydrocarbon petroleum products. Remediation of saturated soils may also be obtained by employment of the present invention. In particular the present invention employs microporous diffusers injecting duo-gas bubbles into aquifer regions to encourage biodegradation of leachate plumes which contain biodegradable organics, or Criegee decomposition of leachate plumes containing dissolved chlorinated hydrocarbons.
2. Background Prior Art
The introduction of air bubbles into aquifers for the purpose of remediation is a recent advancement in in-situ treatment of groundwater. (Marley, et. al, 1992; Brown et. al., 1991). Contained air entrainment has been used for many years to provide vertical movement of water in low-head aquariums and in the development of public well supplies (Johnson, 1975). Aeration of aquifers for plume management was suggested to accelerate bacterial degradation of dissolved organic compounds (JRB, 1985). As the bubble volume increases in density above re-aeration needs by approaching ratios beyond 1 to 10 (1 water to 10 air), gas transfer begins to dominate. In this case, volatile organics may be physically transported from the saturated aquifer to the overlying unsaturated zone (vadose zone).
There is a well recognized need for a simple test to evaluate a potential site to assist with design of sparging systems deployed on a remediation site. Whereas hydraulic tests have been performed for some period of time based upon the well known Theis equation, the introduction of air bubbles (particularly microscopic bubbles) is new. Also, whereas the introduction of air to the pressure vessel is continuous, the production of bubbles, particularly the microscopic variety, is a discrete discontinuous process. Bubbles, once generated, may take preferential pathways, determined largely by the substratum and secondarily by the introduction of pressure (Ji, et. al., 1993).
Applicant is aware of prior art devices that have used injection of air to facilitate biodegradation of plumes. In U.S. Pat. No. 5,221,159 to Billings shows injection of air into aquifer regions to encourage biodegradation of leachate plumes which contain biodegradable organics together with simultaneous soil vacuum extraction.
Also in U.S. Pat. No. 4,730,672, to Payne, there is disclosed a closed-loop process for removing volatile contaminants. However Payne deals only with volatile contaminants. Payne discloses a withdrawal well is surrounded by multiple injection wells. Pressurized air is injected into the ground water through the injection wells, and is withdrawn under vacuum from the withdrawal well whereupon contaminants are removed from the air stream and the air is then recycled through the system. The U.S. Pat. No. 4,588,506, to Raymond et al., discloses the injection of a diluted solution of hydrogen peroxide into a contaminated soil for enhancing biodegradation of organic contaminants in the soil. Raymond discloses intermittent spiking of the hydrogen peroxide concentration to eliminate biota to increase soil permeability. Raymond has the disadvantage of failing to deliver of oxygen throughout the system, and depends on a complicated process of hydrologic management of the subsurface which has rendered the process uneconomical.
However, notwithstanding the teachings of the prior art, there has not been shown a method of remediating a site in a controlled manner of poorly biodegradable organics, particularly dissolved chlorinated solvents without vacuum extraction, which is adapted to the specific site and at an economical cost. The present invention accomplishes this by employing microporous diffusers injecting duo-gas bubbles into aquifer regions to encourage biodegradation of leachate plumes which contain biodegradable organics which overcomes at least some of the disadvantages of prior art.
SUMMARY OF THE INVENTION
The present invention relates to injection of oxidizing gas in the form of small bubbles into aquifer regions to encourage in situ remediation of subsurface leachate plumes. The present invention is directed to sparging apparatuses and methods of in situ groundwater remediation for removal of dissolved chlorinated hydrocarbons and dissolved hydrocarbon petroleum products. Remediation of saturated soils may also be obtained by employment of the present invention. In particular the present invention employs microporous diffusers injecting duo-gas bubbles into aquifer regions to encourage biodegradation of leachate plumes which contain biodegradable organics, or Criegee decomposition of leachate plumes containing dissolved chlorinated hydrocarbons.
The following methods and apparatuses for removal contaminants from soil and an associated subsurface groundwater aquifer using microporous diffusers and duo-gas systems are particularly useful in that they promote extremely efficient removal of poorly biodegradable organics, particularly dissolved chlorinated solvents, without vacuum extraction, and wherein remediation occurs by destroying organic and hydrocarbon material in place without release of contaminating vapors.
In the present invention the groundwater and soil remediation system comprises oxidizing gas encapsulated in microbubbles generated from microporous diffusers matched to soil porosity. A unique bubble size range is matched to underground formation porosity and achieves dual properties of fluid like transmission and rapid extraction of selected volatile gases, said size being so selected so as to not to be so small as to lose vertical mobility. In order to accomplish a proper matching, a prior site evaluation test procedure is devised to test effectiveness of fluid transmission at the site to be remediated.
The advantage of controlled selection of small bubble size promotes rapid extraction of selected volatile organic compounds, such as PCE, TCE, or DCE with an exceptionally high surface to gas volume ratio. The dual capacity of the small production and rise time is matched to the short lifetime of an oxidative gas, such as ozone to allow rapid dispersion into water saturated geological formations, and extraction and rapid decomposition of the volatile organic material. The unique apparatus of the present invention provides for extraction efficiency with resulting economy of operation by maximizing contact with oxidant by selective rapid extraction providing for optimum fluidity to permit bubbles to move like a fluid through media which can be monitored.
The use of microporous sparging points provides a more even distribution of air into a saturated formation than the use of pressurized wells. A sparge system installed to remediate contaminated groundwater is made more cost-effective by sparging different parts of the plume area at sequenced times. Through the proper placement of sparge locations and sequence control, any possible off-site migration of floating product is eliminated. With closely spaced sparge points, water mounding is used to advantage in preventing any off-site escape of contaminant. The mounding is used to herd floating product toward extraction sites. In the present invention, the concept of sparge system manipulation is predicated upon a thorough knowledge of the features of the groundwater or saturated zones on a site selected for remediation. Balancing the volume of air to the system sparge loci enables control of sparging efficiency and balancing of any downgradient movement of a contaminated plume while remediation is accomplished. Critical to sparge system design and accomplishment of any of the above points is to initially perform a “sparge point test” for the purpose of evaluating the characteristics of the site for matching purposes.
Furthermore, the present invention overcomes the limitations expressed above of the prior technology. The invention employs the well recognized Criegee mechanisms which describes the
Fish & Richardson P.C.
Morrison Betsey J.
Simmons David A.
LandOfFree
Groundwater and soil remediation with microporous diffusion... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Groundwater and soil remediation with microporous diffusion..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Groundwater and soil remediation with microporous diffusion... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2607560