Abstract:
Disclosed is a three-tank water treatment system. In operation, water flows through each tank in succession, with each tank performing one or more treatment operations. By allocating a separate tank for the copper/zinc redox alloy filtration medium, some embodiments of this system allow for a greater amount of the redox alloy to be deployed than is practical with existing systems. This increases the effectiveness of this type of filtering and increases the lifetime between necessary changes of the filtration media. In a preferred embodiment, the three tanks are placed in a vertical column. Each of the uppermost two tanks has one dome hole or bulkhead hole near its top and another near its bottom. When the time comes to exchange the filtration medium in a tank, the top and bottom holes are opened, and the media is easily drained out and replaced.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Patent Application 60/837,548, “Triple-Tank System and Method for Treating Water,” which was filed on Aug. 14, 2006, and which is incorporated herein by reference in its entirety. 
     
     FIELD OF THE INVENTION 
       [0002]    The present invention is related generally to water treatment, and, more particularly, to water-treatment systems using a redox alloy. 
       BACKGROUND OF THE INVENTION 
       [0003]    Water-treatment systems typically direct municipal or well water through a series of filtration stages where each stage filters out one or more undesirable elements found in the water. For example, there can be stages to soften the water, to remove iron and other heavy metals, to kill bacteria, and to remove organic chemicals and inorganic contaminants. A copper/zinc redox alloy can be used in one stage to reduce the amount of dissolved chlorine and to kill bacteria and other microorganisms. 
         [0004]    Over time, contaminants accumulate in the filtration media and must be removed. To do this, the water-treatment system is periodically “backwashed” which releases contaminants from the filtration media and dumps them into a waste-water stream. 
         [0005]    Even with periodic backwashing, filtration media eventually wear out and must be replaced. In existing systems, this is a messy and time-consuming process. To avoid this job, many systems are run long beyond their effective lives and begin to produce water of lesser quality. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    In view of the foregoing, the present invention provides a three-tank water treatment system. In operation, water flows through each tank in succession, with each tank performing one or more treatment operations. By allocating a separate tank for the copper/zinc redox alloy filtration medium, some embodiments of this system allow for a greater amount of the redox alloy to be deployed than is practical with existing systems. This increases the effectiveness of this type of filtering and increases the lifetime between necessary changes of the filtration media. 
         [0007]    In a preferred embodiment, the three tanks are placed in a vertical column. Each of the uppermost two tanks has one dome hole or bulkhead hole near its top and another near its bottom. When the time comes to exchange the filtration medium in a tank, the top and bottom holes are opened, and the media is easily drained out and replaced. (In some embodiments, the lowermost tank has only the one hole near its top. The filtration medium is replaced by vacuuming out the old medium and then pouring in the new medium.) 
     
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0008]    While the appended claims set forth the features of the present invention with particularity, the invention, together with its objects and advantages, may be best understood from the following detailed description taken in conjunction with the accompanying drawings of which: 
           [0009]      FIG. 1  is a perspective view of the outside of a three-tank water-treatment system according to one embodiment of the present invention; 
           [0010]      FIG. 2  is a cut-away view of the water-treatment system of  FIG. 1 ; 
           [0011]      FIG. 3  is a cut-away view of an alternative embodiment of the water-treatment system of  FIG. 2 ; 
           [0012]      FIG. 4  is a structural view of the screen and coupler between the tanks; 
           [0013]      FIG. 5  is a flowchart of a method for treating water according to one embodiment of the present invention; and 
           [0014]      FIG. 6  is a flowchart of a method for backwashing a water-treatment system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    Turning to the drawings, wherein like reference numerals refer to like elements, the present invention is illustrated as being implemented in a suitable environment. The following description is based on embodiments of the invention and should not be taken as limiting the invention with regard to alternative embodiments that are not explicitly described herein. 
         [0016]      FIG. 1  is an outside view of a three-tank water-treatment system  100  according to the present invention. Sitting on top is a valve assembly  102 . The valve assembly  102  includes connection ports (not shown) (1) to a source of water to be treated (e.g., water from a municipal water supplier), (2) to an output for treated water (e.g., to pipes that supply a home or an office), and (3) to a drain for waste water used during backwashing (e.g., a municipal sewer.) Inside the valve assembly  102  are valves (also not shown) that direct the flow of water through the water-treatment system  100 . The operation of these ports and valves is discussed below. In some embodiments of the present invention, the valve assembly  102  is taken from the existing art and thus need not be described in detail here. 
         [0017]    Below the valve assembly  102  (in the embodiment of  FIG. 1 ) is a stack of three tanks  104 ,  106 , and  108 . Tanks  104  and  106  are connected to one another by a coupler  110 . Tanks  106  and  108  are similarly connected to one another by a second coupler  112 . 
         [0018]    As described in more detail below (see  FIGS. 5 and 6  and the accompanying text), the water-treatment system  100  generally operates in two modes. The “treatment” mode is used to produce treated water, while the “backwash” mode regenerates the media in the tanks  104 ,  106 , and  108 . In the treatment mode, the valve assembly  102  takes in water to be treated. The water is then directed to flow successively through the three tanks  104 ,  106 , and  108 . Each tank  104 ,  106 , and  108  contains one or more mechanisms for treating the water as it passes through. For a non-limiting example, the tank  104  contains a copper/zinc redox alloy (such as KDF® marketed by KDF Fluid Treatment, Incorporated, of Three Rivers, Mich.), the tank  106  contains an activated carbon filtering medium, and the tank  108  contains an ion-exchange resin or a nano-technology medium (and possibly also contains gravel). These treatment mechanisms and others are all known in the art, and all may be used in conjunction with the present invention. After being treated successively in the three tanks  104 ,  106 , and  108 , the water is directed by the valve assembly  102  to the output port where it is distributed for use. 
         [0019]    In the backwash mode of operation (often scheduled at night when there is little or no demand for treated water), the valve assembly  102  directs backwash water through the three tanks  104 ,  106 , and  108  in succession, but usually in the opposite direction than in the treatment mode. The backwash water regenerates or backwashes the treatment mechanisms in the three tanks  104 ,  106 , and  108  as is well known in the art. The backwash water is then directed by the valve assembly  102  to the drain port. 
         [0020]    The physical arrangement of the water-treatment system  100  of  FIG. 1  is illustrative only. Many other physical arrangements are possible in keeping with the structure and operation of the invention as claimed. The particular arrangement shown in  FIG. 1  is often preferred because it takes up exactly the same amount of floor space as do many prior-art water-treatment systems. This arrangement thus eases the replacement of a prior-art system with a system according to the present invention. 
         [0021]    In the embodiment of  FIG. 2 , the water-treatment system  100  of  FIG. 1  is cut-away to shown its internal structure. Running from the valve assembly  102  through the three tanks  104 ,  106 , and  108  is a distributor tube  200 . (More of the internal structure of this embodiment is shown in  FIG. 4  and described in the accompanying text.) 
         [0022]    The operation of the water-treatment system  100  is now described with reference to the structure of  FIG. 2  and the method illustrated in  FIG. 5 . When in treatment mode, the valve assembly  102  receives untreated water through an input port (step  500  of  FIG. 5 ) and directs the untreated water to flow into the top tank  104  (step  502 ). (Generally, water is “directed” simply by opening and closing valves in the valve assembly  102 . Water pressure from the water delivery system then causes the water to flow in the desired path.) The water is filtered or otherwise treated by the medium in the top tank  104  (step  502 ) and then flows through the coupler  110  into the second tank  106 , the water passing around, and not entering into, the distributor tube  200  (step  504 ). In a like manner, the water passes through the media in tanks  106  and  108  where it is further treated (steps  504  and  506 ). When the now treated water reaches the bottom of the lowermost tank  108 , it flows into the end  202  of the distributor tube  200  (step  508 ). The treated water flows up the distributor tube  200  to the valve assembly  102  (step  510 ). From there, the treated water flows out the output port of the valve assembly  102  to distribution pipes and ultimately to faucets and the like (step  512 ). 
         [0023]    When the water-treatment system  100  is in backwash mode, the valve assembly  102  receives water through an input port (step  600  of  FIG. 6 ) and directs the water to flow down the distributor tube  200  (step  602 ). The water does not come into contact with the media in any of the tanks  104 ,  106 , and  108  until it reaches the end  202  of the distributor tube  200 . There, the water flows into the lowermost portion of the medium in the lowermost tank  108  (step  602 ). The water is forced to flow up through the medium of this tank (step  604 ), through the coupler  112 , and into the tank  106  (step  606 ). (Note that the backwash water flows “up” in the embodiment of  FIG. 2 , but that in general the tanks  104 ,  106 , and  108  can be arranged in a manner different from the vertical stack shown.) In like manner, the water flows up through the media of the upper two tanks  106  and  104  (steps  606  and  608 ). When the backwash water leaves the top tank  104  and reaches the valve assembly  102  (step  610 ), it is directed to a drain port and then out to a sewer (step  612 ). During this backwash operation, impurities collected by the media in the tanks  104 ,  106 , and  108  are removed and pass into the drain. Also, the reverse flow of water through the media helps to “fluff up” the media, breaking up clumps that may form which would reduce the effective surface area of the media and decrease performance. 
         [0024]    As is well known in the art, the media used in water treatment eventually lose their potency and need to be replaced. In the embodiment of  FIG. 2 , dome holes  204  are placed at the top and bottom shoulders of the top  104  and middle  106  tanks and on the top shoulder of the lowermost tank  108 . In normal operation, these domes holes are closed with plugs. They are opened in order to easily replace the media in the tanks  104 ,  106 , and  108 . To replace the medium in one of the two upper tanks  104  and  106 , the top and bottom dome holes  204  of the tank are opened, the old medium flows out the bottom dome hole  204 , and the new medium is poured (or pumped) in through the top dome hole  204 . The lowermost tank  108  shown in the embodiment of  FIG. 2  has a flat bottom (or “foot” or “stand”) rather than a lower shoulder in order to securely support the weight of the entire water-treatment system  100  on a floor. Therefore, the lowermost tank  108  makes do without a lower dome hole  204 . To replace the medium in this tank  108 , its upper dome hole  204  is opened, the old medium is vacuumed out, and the new medium is then poured in. While this is less convenient than the procedure usable with the upper two tanks  104  and  106 , it is acceptable in most installations because the lowermost tank  108  can be sized to include enough medium that it need not be replaced often. 
         [0025]      FIG. 3  is an alternative to the embodiment of  FIG. 2 . Instead of the dome holes  204 , the tanks  104 ,  106 , and  108  include bulkheads  300  with plugs. When replacing the medium in the tank, the bulkheads  300  are used in the same manner as the dome holes  204  discussed above. The choice between dome holes  204  and bulkheads  300  can be based on a number of well known engineering factors, including the curvature and area of the shoulders of the tanks  104 ,  106 , and  108 . 
         [0026]    For clarity&#39;s sake,  FIGS. 2 and 3  do not show media screens inside the tanks  104 ,  106 , and  108 .  FIG. 4  shows such a media screen  400  between the tanks  104  and  106 . This screen  400  is preferably made of plastic. During normal operation (when the water flows down from the tank  104  to the tank  106 ), the water flows down through the screen  400 , but the screen  400  prevents the treatment medium in tank  104  from flowing into the tank  106 . During backwash operation (when the water flows up from the tank  106  to the tank  104 ), water flows up through the screen  400 , while the screen  400  prevents the treatment medium in tank  106  from flowing into the tank  104 . A similar screen  400  sits between the tanks  106  and  108 . A somewhat differently configured screen (not shown) but serving the same purpose surrounds the end  202  of the distributor tube  200  in the lowermost tank  108 . In some embodiments, another screen sits near the top of the top tank  104  to prevent medium from migrating into the valve assembly  102  especially if the water-treatment system  100  is turned over during shipping. 
         [0027]    The present invention has many advantages over other water-treatment systems. By allocating a separate tank, such as the top tank  104 , to holding a copper/zinc redox alloy, the water-treatment system  100  can hold a significantly greater amount of that alloy than is practical in other systems. For example, in one embodiment of the water-treatment system  100 , the top tank  104  holds thirty five pounds of copper/zinc redox alloy as compared with about two pounds held by other systems. In an average household, this increases the replacement period of this alloy from about a year to seventeen years. In the vertical-stack embodiment illustrated in  FIGS. 1 through 3 , this increased replacement period is gained without increasing the footprint needed by the water-treatment system  100 . Thus, embodiments of the present invention can truly deliver “bottled-quality” water to every faucet in a home or small business without undue increases in maintenance or space requirements over existing systems. 
         [0028]    In view of the many possible embodiments to which the principles of the present invention may be applied, it should be recognized that the embodiments described herein with respect to the drawing figures are meant to be illustrative only and should not be taken as limiting the scope of the invention. Those of skill in the art will recognize that some implementation details, such as the selection and placement of the treatment media in the tanks, are determined by specific situations. Therefore, the invention as described herein contemplates all such embodiments as may come within the scope of the following claims and equivalents thereof.