Liquid purification or separation – Structural installation – Geographic
Reexamination Certificate
1998-09-09
2001-05-01
Simmons, David A. (Department: 1724)
Liquid purification or separation
Structural installation
Geographic
C210S219000
Reexamination Certificate
active
06224757
ABSTRACT:
BACKGROUND OF THE INVENTION
THIS INVENTION relates to the treatment of liquids. More particularly, the invention relates to a mass transfer device fur use in the treatment of an impure liquid, a method of treating an impure liquid, equipment for treating an impure liquid and a component for a borehole for use in the treatment of impure liquids.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a mass transfer device for use in the treatment of an impure liquid, the mass transfer device including
a housing into which the impure liquid and a reagent are to be introduced, the housing having a side wall; and
an impeller assembly, comprising a plurality of impeller blades, rotatably mounted in the housing, at least one impeller blade having a tip which terminates in close proximity to an interior surface of the side wall of the housing and the or each impeller blade being shaped and dimensioned to impart shear forces, at its tip, to liquid and reagent located between the side wall and the tip and to generate a low pressure region at a trailing end of the said tip upon rotation of the blade relative to the side wall, thereby enhancing a reaction between the reagent and impurities in the liquid.
The side wall may be foraminous having openings which are defined in the side wall for allowing flow of the liquid and the reagent from and back into the housing.
The reagent may be gaseous with the openings in the side wall being dimensioned according to physical and dynamic parameters of the device and providing the required resistance to movement through them when the liquid and the reagent are expelled from the housing through the openings.
The tip of each impeller blade may have an edge portion which complements the shape of the interior surface of the side wall. At least the tip of the or each impeller blades may be formed of a catalytic material for enhancing catalytic reaction between the impurities in the liquid and the reagent.
The catalytic material may be selected from the group comprising platinum group metals and may be vanadiumpentoxide.
According to a second aspect of the invention, there is provided a method of treating an impure liquid which includes the steps of
introducing the impure liquid into a housing of a mass transfer device;
introducing a reagent into the housing of the mass transfer device; and
causing rotation of an impeller blade inside the housing thereby imparting shear forces on liquid and reagent located between a tip of the blade and an interior surface of a side wall of the housing and generating a lower pressure zone at a trailing edge of said tip, so that a reaction between the reagent and impurities in the liquid is enhanced.
The method may include the step of discharging treated water into a soil matrix. The method may further include introducing excess reagent into the mass transfer device to enable residual reagent to be entrained in the treated water; and discharging the treated water with the residual reagent through outlet openings of discharge tubes into the soil matrix to effect reaction of contaminants in the soil matrix with the residual reagent. In a preferred embodiment of the invention, the treated water is discharged into the soil matrix to effect oxidation of absorbed organic contaminants in the soil matrix effecting soil washing and leaching and stimulating bacterial activity for further breakdown of adsorbed and absorbed soil contamination.
According to a third aspect of the invention, there is provided equipment for treating an impure liquid, the equipment including
a vessel into which the impure liquid is to be fed;
at least one mass transfer device mountable within the vessel, the device having an impeller assembly which is located inside a housing;
a reagent supply means for supplying reagent to the mass transfer device in the vessel; and
a drive means for causing rotation of the impeller assembly inside the housing.
The reagent may be in the in the form of an oxidant or a reducing agent. The oxidant may be a gaseous oxidant. In particular, the oxidant may be ozone. Thus, the reagent supply means may be an ozone generator which, in use, is mounted above ground surface level or an ozonator installed underground. The reducing agent may be in the form of hydrogen.
The equipment may include a retention means arranged within the vessel upstream from the, or a top mass transfer device, for absorbtion of impurities which are contained in treated water which issues from the mass transfer device. The retention means may be arranged between an upper water impervious packer and a lower water impervious packer. The retention means may comprise a packing of activated carbon, zeolyte, resin, or the like carried in the borehole casing between the lower packing element and the upper packing element. The retention means may serve to enhance oxidation or reduction of complex organic hydrocarbons present in the liquid.
The vessel may be in the form of a borehole casing sunk into a soil matrix. The equipment may include a pump for drawing contaminated liquid to be treated into an interior of the borehole casing at an operatively lower elevation of the borehole casing. It will be appreciated that the borehole casing is of such a length that a lower end of the borehole casing will lie below a surface of the subterranean water, i.e. below the surface of the water table. Then, the borehole casing may include openings arranged about its circumference via which the water can enter the borehole casing.
In a preferred embodiment of the invention, only a lower region of the borehole carries the openings. A filtering means may be arranged about an outer periphery of the lower region of the borehole for inhibiting the ingress of detritus into the borehole casing. The filtering means may be in the form of a gravel pack including graded silica sand.
The equipment may also include a drive means which, in use, drives both the pump and the impeller assembly of the mass transfer device. The drive means may be an electric motor.
The equipment may further include a discharge means for discharging treated liquid from the vessel. The discharge means may include a discharge conduit comprising a plurality of discharge tubes extending radially outwardly from the discharge end of the vessel and having at least one outlet opening which extends into a soil matrix. The discharge means may be arranged below the surface of the ground, at various depths, defined by the hydraulic behaviour of the soil matrix and the yield of the borehole. An annular betonite or cement slurry seal may be located between the vessel and the soil matrix to inhibit flow of treated liquid back into the vessel.
The vessel may alternatively be in the form of a free standing vessel which is used at ground surface level.
According to a fourth aspect of the invention, there is provided a component for a borehole for use in the treatment of impure liquids, the component including a borehole casing, only an operatively lower region of which is screened.
In this specification, the term “impure liquid” includes subterranean contaminated liquids such as water containing industrial effluents and/or metals and hydrocarbon-contaminated water, unless the context clearly indicates otherwise.
In this specification, the term “screened” means, unless the context clearly indicates otherwise, openings defined in the casing.
The invention is now described by way of example with reference to the accompanying diagrammatic drawings.
REFERENCES:
patent: 5180503 (1993-01-01), Gorelick et al.
patent: 5248613 (1993-09-01), Boubicek
patent: 5318698 (1994-06-01), Bernhardt
patent: 5688076 (1997-11-01), Atkins
patent: 5849201 (1998-12-01), Bradley
patent: 39 31 011 (1991-03-01), None
patent: 42 04 059 (1993-08-01), None
patent: 899051 (1982-01-01), None
Lawrence Frank M.
Rapsol Twenty Seven Close Corporation
Simmons David A.
Skinner and Associates
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