Abstract:
A method and apparatus are provided for an advanced water treatment system that includes filtration, physical conditioning, and ultraviolet disinfection elements in a single unit. A control valve controls flow through the system in filtering, backwashing, cleaning, and rinsing modes of operation.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an integrated water treatment apparatus and method suitable for use as a point-of-entry system in the home. More particularly, the present invention relates to an improved home water treatment apparatus and method that integrates several water treatment stages in a single vessel for improved water quality, including particulate filtration for removing sediment and turbidity, physical water conditioning to prevent hard water scale formation and ultraviolet light disinfection for microorganism inactivation. 
       BACKGROUND OF THE INVENTION 
       [0002]    Point-of-entry water treatment arrangements for use in homes have been available for some time. These devices are arranged near the home water-service entry point to provide whole-house water treatment. The point-of-entry devices in common use range from simple particulate filter elements for filtering solid particles present in the incoming water, to more complex filter elements for removing specific dissolved chemicals present in the incoming water, such as chlorine, hardness (calcium and magnesium ions) and organic contaminants. Point-of-entry water treatment units may also incorporate ultraviolet lamps for disinfection by exposing incoming water to ultraviolet light in order to inactivate pathogens and other microorganisms that may be present in the water. 
         [0003]    Typically, separate treatment units must be used for removal of particulate, chemical and microbial contaminants in water for household use. It is therefore desirable to provide in a unitary vessel a treatment system for removing particulates and chemicals, for conditioning hard water (to prevent scale formation), and for disinfection of microorganisms. Desirably, such a vessel is of a relatively compact size and is one that is adaptable for retrofitting into existing household plumbing systems. 
         [0004]    The first device to incorporate an ultraviolet (UV) light disinfection device inside a filter pressure vessel was described in U.S. Pat. No. 5,584,411, specifically a tank head that permits a UV lamp and UV-resistant tube to be attached thereto with their respective opposite ends suspended in the center of the tank vessel. The inlet and outlet ports of the tank head allow flow to be directed downwardly through the filter vessel, around the bottom end of the tube and then upwardly within the tube where water is exposed to UV light for disinfection treatment. This system was subsequently commercially developed by Cuno Water Treatment Company as the Biolite Ultraviolet System, which is explicitly incorporated by reference. Another system combined the aforementioned tank head technology with a granular media pressure filtration process to provide both filtration and UV disinfection in a single vessel, as disclosed in U.S. Pat. No. 5,916,439. Another system combined granular media pressure filtration and UV disinfection with a filter control valve that controls flow through the pressure filter and provides automatic periodic cleaning of the filter bed, as disclosed in U.S. patent application Ser. No. 11/029,857. While these devices meet the objective of providing a compact in-home water treatment system with capability to provide both filtration and disinfection treatment of water in a unitary vessel, none of them have incorporated a physical water conditioning device, such as the magnetic device disclosed in U.S. Pat. No. 4,299,700. This type of device avoids the need for using ion exchange media for removing hardness from water, which must be regenerated within the pressure vessel every few days using salt. A physical conditioning system is desirable for hard water treatment to prevent calcium carbonate (or lime) scale formation in the household plumbing system, as well as on the UV lamp sleeve of the treatment apparatus which operates at a high surface temperature and so is susceptible to fouling by calcium carbonate scale. 
         [0005]    It is therefore an object of the present invention to provide a compact point-of-entry water treatment system for the home, small business or commercial use that incorporates three water treatment processes in a single pressure-rated vessel, specifically granular media filtration for particle and turbidity removal, UV disinfection for microorganism inactivation, and a physical water conditioner when treating water supplies with moderate to high hardness levels. It is another object to provide a physical water conditioning unit positioned between the filter media and UV lamp assembly in a pressure-rated vessel to condition the filtered water to prevent lime scaling of the UV lamp sleeve as water flows through the UV disinfection tube. It is a further object to provide a physical water conditioning unit in a pressure-rated vessel to condition the filtered water to prevent lime scale and scum formation, water spotting and other aesthetic water quality problems in household plumbing systems associated with water supplies with moderate to high hardness. 
       SUMMARY OF THE INVENTION 
       [0006]    Briefly stated, the present invention relates to a water treatment system that includes granular media filtration, physical water conditioning and ultraviolet disinfection elements in a single pressure-rated vessel. 
         [0007]    In accordance with the preferred embodiment of the present invention, a water treatment system is provided that includes a cylindrical pressure vessel defining an opening at the top end of the vessel. A flow transfer tube assembly, consisting of an upper flow transfer tube, UV reactor tube and physical water conditioning unit, is centrally positioned within the pressure vessel and extends vertically from the bottom of the pressure vessel through the top opening in the pressure vessel. A UV lamp assembly is concentrically disposed within the UV reactor tube to disinfect water as it flows upwardly through the tube. A bed of granular filter media is disposed within the pressure vessel and substantially surrounds at least a portion of the flow transfer tube assembly. A coupling is adapted to receive and retain the upper flow transfer tube and UV lamp assembly, while sealably engaging the top opening in the pressure vessel. A flow control valve is mounted on the coupling and is adapted to control water flow through the flow transfer tube assembly and pressure vessel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a cross-sectional side view of a water treatment system showing a flat-plate type filter media retainer and single-stage physical water conditioning unit according to a preferred embodiment of the present invention. 
           [0009]      FIG. 2  is a cross-sectional side view of the bottom portion of a treatment system showing a nozzle-type filter media retainer and single-stage physical water conditioning unit according to the embodiment illustrated in  FIG. 1 . 
           [0010]      FIG. 3  is a cross-sectional side view of a single-stage physical water conditioning unit for a water treatment system according to the embodiment illustrated in  FIG. 1 . 
           [0011]      FIG. 4  is a cross-sectional side view of a two-stage physical water conditioning unit for a water treatment system according to the embodiment illustrated in  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0012]      FIG. 1  is a cross-sectional side view with elements shown in phantom of a treatment system according to the preferred embodiment of the present invention. In this example the treatment system  10  includes a vertical cylindrical pressure vessel  12  such as those commonly used in point-of-entry home water treatment systems. Pressure vessel  12  may be constructed of any suitable material such as polyglass, fiberglass, or other materials commonly used to construct such vessels. Pressure vessel  12  defines a top opening  14  at one end of vessel  12 . 
         [0013]    Also as shown here, the top opening  14  in vessel  12  may be threaded to accept a threaded end  16  of a coupling  18  through which water may be supplied to and drawn from vessel  12 . Generally, coupling  18  directs water flow into and out of the vessel  12 . 
         [0014]    The water treatment system  10  includes a flow transfer tube assembly  20 , which extends from the bottom of vessel  12  through top opening  14  along the vessel&#39;s longitudinal centerline axis, and consists of upper flow transfer tube  22 , UV reactor tube  24 , physical water conditioning device  26  and pipe nipples  23 , 27 . Upper flow transfer tube  22  is sealably connected with coupling  18  and, through coupling  18 , provides a path for water flow into or out of vessel  12 . 
         [0015]    UV reactor tube  24 , which may include a threaded, socket or welded top end connection which sealably engages the bottom end of flow transfer tube  22 , extends further into pressure vessel  12  along the vessel&#39;s longitudinal centerline axis. The outside diameter of UV reactor tube  24  is preferably slightly smaller than top opening  14  so that it can be lowered into pressure vessel  12  during installation, while providing as large a diameter as possible to reduce the velocity of water flow though the reactor tube, thereby maximizing UV disinfection exposure time of the water. The length of UV reactor tube  24  is determined based on the minimum exposure time required for adequate disinfection and is typically 24 to 36 inches in length. 
         [0016]    Physical conditioning unit  26 , which may include a threaded or socket top end which sealably engages half-coupling  25  at the bottom end of UV reactor tube  24 , such as through pipe nipple  23 , extends further into pressure vessel  12  along the vessel&#39;s longitudinal centerline axis. The length and diameter of physical conditioning unit  26  is determined based on process design requirements such as the minimum exposure time and maximum water velocity required for effective physical water conditioning and is typically 9 to 18 inches in length. 
         [0017]    Water treatment system  10  further includes a filter media retainer  28 . Filter media retainer  28  may include a threaded or socket end at its center, which sealably engages the bottom end of physical conditioning device  26 , such as through pipe nipple  27 . Furthermore, filter media retainer  28  is adapted to prevent granular filter media  30  from entering tank plenum  32  and transfer tube assembly  20 , and may comprise a flat-plate type device  21  with narrow slotted apertures  29 , as shown in  FIG. 1 , or a nozzle-type device  31  with narrow slotted apertures  33 , as shown in  FIG. 2 , or similar type of system. 
         [0018]    A bed of granular filter media  30  is located within pressure vessel  12  and substantially surrounds at least a portion of transfer tube assembly  20 . The top of filter bed  30  is spaced below the top of pressure vessel  12  to provide adequate clearance for expanding the bed during a backwash cycle, as will be discussed later. Filter media bed  30  may comprise a single layer of filter media (as shown in  FIG. 1 ) or multiple filter media layers and is provided to remove suspended or dissolved contaminants from the water. The exact type and configuration of filter media bed  30  for a particular application is based on specific water quality and treatment requirements. 
         [0019]    An ultraviolet lamp assembly  34  is disposed within upper flow transfer tube  22  and UV reactor tube  24 , coincident with the centerline longitudinal axes of tubes  22 ,  24 . The bottom end of ultraviolet lamp assembly  34  preferably extends to just above the bottom end of UV reactor tube  24  to maximize the UV irradiance field within the tube for disinfection. Ultraviolet lamp assembly  34  provides a final disinfection treatment stage following filtration and physical water conditioning within pressure vessel  12 . Furthermore, ultraviolet lamp assembly  34 , as will be discussed further below, comprises a low-pressure germicidal lamp  36  housed inside a closed-end quartz sleeve  38 . The top end of ultraviolet lamp assembly  34  is secured within coupling  18 . A lamp end connector  40  located on top of coupling  18  is threadably received into coupling  18  with O-ring seals (not shown) to provide a watertight seal. A power cord  42  passes through an opening in end connector  40  and its opposite end is connected to lamp power supply plug  44 . Lamp power supply plug  44  may contain a lighting ballast for igniting the lamp. 
         [0020]    Physical conditioning unit  26 , located within pressure vessel  12 , has its top end sealably connected with half-coupling  25  and its bottom end sealably connected with filter media retainer  28 . As is further illustrated in  FIG. 4 , physical conditioning unit  26  may consist of a single-stage unit  35  consisting of a closed cylindrical conduit  44  with an inlet end  46  and an outlet end  48 . Inlet end  46  may include threaded connection  45 , as shown in  FIG. 4 , to sealably engage physical conditioning unit  26  with filter media retainer  28 . Likewise, outlet end  48  may include threaded connection  47  to sealably engage physical conditioning unit  26  with half-coupling  25  of UV reactor tube  24 . A series of magnet elements  50  are positioned within closed conduit  44  along its centerline axis. Magnet elements  50  preferably consist of a series of multi-reversing magnets with north and south magnetic poles adjoining each other to produce a strong reversing magnetic field within the annular space  52  formed between magnets  50  and inner wall  54 . This type of magnetic field is best suited to effect changes in the crystallization behavior of minerals present in the water to prevent formation of adherent scale on UV lamp assembly  34  and in the household plumbing system served by water treatment system  10 . 
         [0021]    As is further illustrated in  FIG. 4 , physical conditioning unit  26  may consist of a two-stage unit  37  including a smaller first-stage physical conditioning unit  39  and a larger second-stage physical conditioning unit  41 . Both units are operated in series with water either flowing through the first smaller unit and then the second larger unit, or flowing through the first larger unit followed by the second smaller unit. Both units have the same components as described previously for single-stage unit  35 , but the physical dimensions of the two stages of the unit are different. The two-stage physical conditioning arrangement is preferred when treating water supplies with highly variable flow rates, since the effectiveness of the magnetic conditioning unit is strongly related to flow velocity passing through the magnetic field. At low flows, the smaller unit  39  is effective in treating water at an optimum flow velocity, whereas at higher flows, the larger unit  41  is effective in treating water at an optimum flow velocity. 
         [0022]    Water treatment system  10  may further comprise a control valve assembly  56 , as shown in  FIG. 1 , that communicates with coupling  18  via a valve receptacle  58  and interconnection pipe  60 . Control valve assembly  56  may be any of a variety of manually or automatically operated commercially available units and can include inlet, outlet, drain, and possibly chemical feed connections for operation of water treatment system  10 . In addition, an automatically operated control valve assembly  56  may include a microprocessor and timer to control the frequency and duration of filter, backwash, and possibly, chemical cleaning and rinse cycles. For example, some automatically operated units that may be suitable include the Autotrol unit by GE Osmonics, Fleck 5600 by Pentair Water Corporation, and the WS1 by Clack Corporation. 
         [0023]    In operation, pressurized, untreated water is supplied to treatment system  10  from the home&#39;s plumbing system to control valve assembly  56 . In the typical filtering mode, control valve assembly  56  directs untreated water through internal inlet passageways (not shown) in control valve receptacle  58 , interconnecting pipe  60  and coupling  18 . Untreated water then flows from coupling  18 , around the outside of upper flow transfer tube  22  and into pressure vessel  12 . Once in pressure vessel  12 , the untreated water flows through filter media bed  30 , through filter media retainer  28 , through tank plenum  32 , and into the bottom end of flow transfer tube assembly  20 . The water then flows up through physical conditioning unit  26 , through UV reactor tube  24 , around ultraviolet lamp assembly  34  and into the upper flow transfer tube  22 . Water exits upper flow transfer tube  22  and flows through internal outlet passageways (not shown) in coupling  18 , interconnection pipe  60  and valve receptacle  58 , and into control valve assembly  56  to the supply line of the home&#39;s plumbing. 
         [0024]    Since the filter media may require periodic cleaning to prevent clogging of filter media bed  30 , a backwash cycle is provided to reverse flow through the system and clean the filter media. In a backwash cycle, control valve assembly  56  switches to direct, untreated water from the household&#39;s supply line through internal inlet backwash passageways (not shown) in valve receptacle  58 , connector pipe  60  and coupling  18 . From coupling  18 , water flows into upper flow transfer tube  22 , through UV reactor tube  24 , around ultraviolet lamp assembly  34 , through physical conditioning unit  26 , and into tank plenum  32  at the bottom of tank  12 . The water then flows from tank plenum  32 , through slotted apertures  29  of filter media retainer  28 , into and up through filter media bed  30 , and out of pressure vessel  12  into coupling  18 . From coupling  18 , water flows through internal outlet backwash passageways (not shown) in coupling  18 , interconnection pipe  60 , valve receptacle  58  and out of control valve assembly  56  to a drain line of the home&#39;s plumbing. 
         [0025]    The preferred embodiments and variations thereof illustrated in the accompanying figures and/or described above are merely exemplary and are not meant to limit the scope of the invention. It is to be appreciated that numerous variations of the invention have been contemplated as would be obvious to one of ordinary skill in the art with the benefit of this disclosure. All variations of the cover that read upon the appended claims are intended and contemplated to be within the scope of the invention.