Abstract:
A permeable wall for the in situ treatment of groundwater flowing therethrough is formed by a plurality of hexagonal cells removably placed in a frame in watertight relation to the frame and each other. The frame is mounted in a gate between barriers or pilings in the flow path of the groundwater. Each cell is formed by a hexagonal shell of water impermeable material defining a central chamber opening therethrough and containing a permeable water treatment material. Sealing tongues project from a portion of the shell, and sealing grooves are defined in another portion. The tongues on one cell are received in sealing grooves on an adjacent cell when the cells are mounted in the frame. Removable panels are mounted on the frame to prevent water flow when the cells are being inserted or removed. The same construction can be utilized for other fluid-solid reactors.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Provisional Application Ser. No. 60/098,407, filed Aug. 31, 1998, by Marek Henryk Zaluski, et al., for HONEYCOMB CELL FOR GROUNDWATER TREATMENT APPARATUS. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to fluid-solid reactors. More particularly, the present invention relates to a permeable, reactive, wall element finding particular but not exclusive use in the subsurface in situ treatment of contaminated groundwater to remove contaminants therefrom. 
     2. Description of the Prior Art 
     U.S. Pat. No. 5,487,622 describes a barrier wall construction that confines and directs the underground flow of contaminated groundwater. openings or gates in the wall contain water permeable solid treatment material to remove the contaminants f rom th e water as it flows through the gate and material. U.S. Pat. No. 5,624,552 describes a barrier wall with a gate that includes a removable basket containing the treatment material. The basket can be removed from the gate by using a crane and the treatment material replaced or rejuvenated. 
     OBJECTS OF THE INVENTION 
     It is the principal object of the present invention to provide an improved permeable solid structure containing reactive material for reaction with fluids flowing therethrough, and more particularly for reaction with contaminated groundwater to remove contaminants therefrom. 
     Another object of the present invention is to provide a structure of the foregoing character which facilitates the removal and regeneration, rejuvenation or replacement of the reactive solid media or material. 
     A further object of the present invention is to provide an in situ, underground barrier apparatus for the removal of contaminants from groundwater in which change of the reactive material is readily and easily accomplished without the use of heavy equipment such as cranes or the like. 
     Still a further object of the present invention is to provide an improved permeable wall that is watertight except for the permeable reactive material through which the contaminated groundwater flows. 
     Still another object of the present invention is to provide a permeable wall of the foregoing character in which the permeable reactive treatment material can be readily replaced or rejuvenated. 
     Still another object of the present invention is to provide a permeable wall of the foregoing character in which the rejuvenated or replaced reactive treatment material can be readily an easily re-inserted into the in situ barrier gate for further use. 
     Other objects and advantages of the present invention will become apparent as the following description proceeds, taken in conjunction with the accompanying drawings. 
     SUMMARY OF THE INVENTION 
     In one specific aspect, the present invention is embodied in a permeable wall for the in situ treatment of groundwater flowing therethrough for the purpose of removing contaminants therefrom. The water is channeled to the permeable wall by in ground barrier walls or piling. The permeable wall is formed by a frame having bottom and side walls mounted in a gate between the barrier walls. A plurality of hexagonal cells are removably placed in the frame in watertight relation to the frame and each other. Each cell is formed by a hexagonal shell of water impermeable material, defining a central chamber extending therethrough. A water permeable reagent is contained in the shell chamber for removing contaminants from groundwater flowing through the permeable wall. More particularly, each cell is formed by a regular hexagonal shell of water impermeable material, defining opposed hexagonal faces joined by a peripherally hexagonal edge. The preferred sealing structure is formed by a peripheral sealing tongue projecting from each of three adjoining faces of the hexagonal edge and sealing grooves on the other three adjoining edge faces for sealingly receiving projecting tongues on a superimposed or adjoining cell in the wall. The shell further defines a central chamber opening into the faces of the shell, and a water permeable reagent is contained in the central chamber for removing contaminants from groundwater flowing therethrough. 
     In its more general aspects, of the present invention is embodied in a fluid permeable solid reactor element formed of cells of reactive material capable of reaction with a fluid flowing through the cells. The permeable reactor element is formed, as described above, by a plurality of hexagonal cells supporting solid, fluid permeable, reactive material. The cells are removably contained in a frame in fluid tight relation to each other. Each cell is formed by a hexagonal shell of fluid impervious material defining a central chamber extending through the cell and containing a reactive reagent capable of reaction with the fluids flowing through the permeable element. The construction of the individual cells is as described above. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an in situ barrier with a gate system therein incorporating a honeycomb structure embodying the present invention containing a reactive treatment material for removing contaminants from groundwater captured by said barrier and flowing through said gate, and with a portion of the front screen broken away. 
     FIG. 2 is an enlarged perspective view of the barrier gate shown in FIG. 1 with a portion of the front screen removed and part of the top cover broken away to show the honeycomb cells containing the reactive treatment material. 
     FIG. 3 is a front elevation view of the barrier gate shown in FIG. 2, with the front screen removed. 
     FIG. 4 is a side elevation view of the barrier gate shown in FIG.  3 . 
     FIG. 5 is a top plan view of the barrier gate shown in FIG.  3 . 
     FIG. 6 is a section view taken substantially in the plane of line  6 — 6  on FIG.  3 . 
     FIG. 7 is a section view taken substantially in the plane of line  7 — 7  on FIG.  4 . 
     FIG. 8 is a schematic view similar to FIG. 7 but with the honeycomb forming cells removed. 
     FIG. 9 is a perspective view of a honeycomb cell assembly containing reactive treatment material for use in the apparatus gate shown in FIG.  2 . 
     FIG. 10 is a front elevation view of a honeycomb cell assembly of the character shown in FIG. 8 with portions broken away to show the seals. 
     FIG. 11 is a top plan view of the honeycomb cell shown in FIG.  9 . 
     FIG. 12 is a bottom plan view of the honeycomb cell shown in FIG.  9 . 
     FIG. 13 is a side elevation view of the honeycomb cell shown in FIG.  9 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention, in one specific form as shown in FIG. 1, is embodied in a permeable wall or panel element  20  incorporating a reactive treatment material  21  and forming a gate  22  in an in situ groundwater barrier  23  formed by the gate  22  and large barrier panels or piling  24  on either side thereof. Groundwater containing dissolved and suspended contaminants, often as a plume  27 , encounters the barrier  23  and is thereby forced or channeled to flow through the permeable wall or panel element  20  forming the gate  22  wherein the contaminants are removed from the groundwater by the reactive treatment material  21 . 
     In its preferred form, the permeable wall or panel element  20  is formed by a plurality of cells  25  each containing a body of reactive treatment material and defining a honeycomb structure  26  through which the contaminated groundwater must flow. Each cell forming the honeycomb is removable and replaceable within the wall or panel element  20  so that the reactive treatment material  21  contained therein can be readily rejuvenated and returned to the gate. 
     To this end, the wall or panel element  20  is formed by a frame  28  having spaced vertical sidewalls  29  integrally joined by a bottom wall  30 , and a top cover  31  removably spanning the sidewalls  29  parallel to the bottom wall. The frame has a height, width and depth sufficient to fill the gate  22  between the barrier panels  24  forming the in situ barrier  23 . The frame  28  is formed of a corrosion resistant material such as a plastic material, for example a polycarbonate, or a corrosion resistant or coated metal, or may be formed of cast concrete, either precast or cast in place. The frame  28  is either permanently formed in place or removably attached to the walls  24  of the impermeable barrier  23 . 
     To prevent entrance into the frame  28  of aquifer matrix or pea gravel (not shown) that is placed adjacent to the frame  28  and panel element  20  to homogenize the flow of water and prevent packing of dense soil adjacent to the element  20 , the front and rear faces  32 , 33  of the frame  28  are covered by screens or foraminous grids  34 , 35  secured to the frame side walls  29  and bottom wall  30  (FIGS.  6 , 7 ). 
     Provision is made to close the frame  28  and cell element  20  of the gate against the flow of water when the honeycomb elements or cells  25  are being removed or inserted. To this end, as shown in FIG. 8, vertically extending elongated channels  36  are mounted on the rear face  33  of the frame  28  to serve as retaining guides for the insertion of one or more water impermeable membranes or panels  38 . Such a sealing panel or panels  38  can be slid in and out of the channels  36  to prevent groundwater from flowing through the gate  22 . 
     For purposes of receiving and retaining in a honeycomb configuration a multiplicity of cells  25  containing the reactive treatment material  21 , the frame  28  is divided into a plurality of longitudinally and vertically extending compartments  39  by coarse grids or foraminous panels  40  spaced apart from each other and extending between the frame side walls  29  parallel to the front and rear screens or grids  34 , 35 . Groundwater can flow through the frame  28  and compartments  39  and the permeable reactive treatment material  21  contained within the honeycomb cells  25  positioned in the compartments  39 . 
     The honeycomb forming cells  25  are formed by a frame or body  41  having an hexagonal peripheral configuration and a width or thickness equal to the width of each frame compartment  39 . Each hexagonal honeycomb cell  25  defines a peripheral hexagonal edge  42  surrounding and joining opposed faces  44 ,  45 . Each cell further defines a central chamber  43  opening into said faces  44 , 45  and within which a reactive water treatment medium  21  is placed. The medium can be in the form of a plug or cylinder, or can be a loose material, either of which is retained within the chamber  43  in the hexagonal body  41  by screens or foraminous plates  47  on both faces  44 ,  45  thereof. 
     Contaminated groundwater is prevented from flowing between adjoining hexagonal treatment cells  25  by seals  46  on the periphery of each cell. Each cell has an upper half portion  48  and a lower half portion  49 . The upper portion or upper half portion  48  of each hexagonal cell  25  defines sealing grooves  50 . Elastic or flexible ribs or tongues  51  project outwardly from a corresponding lower portion or lower half portion  49  of each treatment cell  25  (FIG.  13 ). In order to form a seal between adjoining cells, the projecting elastic or flexible sealing tongues or ribs  51  on one cell are adapted to be inserted into and sealingly received in corresponding sealing grooves  50  in an adjacent element or cell  25 . Other seals or sealing devices or means for sealing adjoining cells to each other may be utilized to advantage. In this manner, the hexagonal treatment cells  25  are tightly sealed one to the other when in use, and yet can be readily removed individually from the frame compartments  39  to permit the reactive medium  21  contained therein to be replaced, rejuvenated or reactived. 
     When loading the frame compartments  39  with the hexagonal treatment cells  25 , each frame compartment  39  is loaded individually. Appropriately shaped bottom blocks  52  and bottom corner blocks  53  are attached along the bottom panel or wall  30  of each frame chamber or compartment  39  and hexagonal treatment cells  25  are stacked therein in a honeycomb configuration. Additional side blocks or solid plugs  54  are positioned adjacent to the frame&#39;s side walls  29  to prevent contaminated water from leaking and escaping around the honeycomb treatment cells  25 . At the top of each loaded compartment the grooves or spaces between the honeycomb elements are also filled with appropriately shaped solid plugs or blocks  55  and the top corner blocks  56 , and the top cover  31  is positioned in place. The bottom blocks  52 , bottom corner blocks  53 , side wall blocks  54 , top blocks  55 , and top corner blocks  56  incorporate appropriate sealing elements which coact with the sealing elements on the cells to prevent water leakage. 
     When loading of the compartments  39  with the hexagonal cells  25  and filler blocks has been completed, the top cover  31  is placed over the upper ends of the frame side walls  29  and holds the cells and blocks tightly within the frame. In order to effect a complete sealing engagement between the various compartment elements, the top cover  31  is clamped to the side walls  29  by appropriate clamps  57  which secure the top cover  31  tightly on the frame  28  and holds the hexagonal cells  25  and blocks  52 ,  53 ,  54 ,  55 , and  56 , securely within the compartments  39 . 
     When filled with treatment material containing hexagonal cells  25 , each compartment  39  presents a honeycomb configuration of such cells. The honeycomb cell  25  arrangements are staggered between adjacent compartments  39  so that a straight flow path is avoided and a tortuous path is provided for the water being treated. 
     To facilitate removal, replacement or placement of the honeycomb cells  25 , each cell  25  includes an appropriate handle (not shown), such as a rigid bar recessed in the top wall of the cell, or a flexible loop or strap, or other device, by which the cell or element may be lifted and raised or removed from a frame compartment or lowered or inserted into a frame compartment  39 . The cells  25  are relatively light in weight making it a simple matter to engage the lifting device or structure with a hook or like device (not shown) either to lift a cell  25  from the frame compartment  39  or to lower a cell  25  into the frame compartment  39 . 
     During the insertion or replacement or removal of the honeycomb material treatment cells  25  from the frame compartments  39 , water entering the frame  28  is blocked by the sealing panels  38  inserted into the guide channels  36  on the back panel of the frame. Such a panel or panels  38  prevent contaminated groundwater from entering the clean aquifer down stream from the gate  22  when the honeycomb cells  25  are being inserted or removed. Water can be removed from the frame  28  and its compartments  39  by a pump (not shown) connected to a port (not shown) defined in the frame  28  to prevent contaminated water from entering the downstream flow after the treatment cells  25  are installed. During installation of the honeycomb cells  25 , any excess water can be continuously removed from the frame  28  and gate  22  and circulated back to the contaminated water flow upstream of the barrier  23 . When the treatment cells  25  are in place, water can be pumped until only clean water is present, and then the sealing panel or panels  38  can be removed, allowing only treated water to flow downstream. 
     The treatment materials may include a variety of physically, chemically or biologically active materials or media. Such reactive materials or media are well known in the art relating to the remediation of contaminated groundwater. Because the honeycomb wall with its hexagonal cell elements is easy to replace, the treatment material content of the cells can be optimized for changes of concentrations with time and composition of the contaminated plume in the groundwater. This includes replacement of chemically or biologically active materials with adsorptive media. Such features can be especially important for a plume that undergoes natural attenuation and may deliver different contaminants to the gate at various times. 
     While a certain illustrative embodiment of the present invention has been shown in the drawings and described above in considerable detail, it should be understood that there is no intention to limit the invention to the specific form disclosed. On the contrary the intention is to cover all modifications, alternative constructions, methods, equivalents and uses falling within the spirit and scope of the invention as expressed in the appended claims.