Abstract:
The invention provides an apparatus having a tank having at least a portion of its surface collapsible such that the tank can be configured in either a deployed position or a smaller stored position. A membrane module is located in the tank. The tank has a feed inlet and a permeate port in communication with the membrane module. When in the deployed position, water enters the inlet and flows through the membrane and out the permeate port in a filtration process. When filtration is no longer required, the tank can be collapsed for transport. The membrane module may remain in the tank when the tank is collapsed.

Description:
[0001]     This is an Application claiming the benefit under 35 USC 119(e) of U.S. Ser. Nos. 60/592,146 filed Jul. 30, 2004 and 60/613,222 filed Sep. 28, 2004. U.S. Ser. Nos. 60/592,146 and 60/613,222 are incorporated herein, in their entirety, by this reference to them. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to water purifications systems, and in particular, to a collapsible tank which may contain filtering membranes and be used for a water treatment system.  
       BACKGROUND OF THE INVENTION  
       [0003]     Numerous water purification systems are known. One known type of water purification systems are mobile or portable systems which are designed to be transportable from place to place by vehicles.  
         [0004]     One such portable system is disclosed in U.S. Pat. No. 6,120,688. The system disclosed includes a rigid tank which is made of material, such as stainless steel, aluminum, polyethylene or the like. The process tank and system disclosed in the patent have the disadvantage of requiring a large vehicle for transportation thereof. Typically, such a system requires a 5/4 ton or greater class of vehicle. In certain applications, such as the military, it is desirable to provide a water purification system and process tank which can be transported by a smaller vehicle, such as a HUMWV (High Mobility Multipurpose Wheeled Vehicle).  
         [0005]     Accordingly, there is a need for a process tank and a water purification system with improved portability, such as those which can transported by smaller vehicles.  
       SUMMARY OF THE INVENTION  
       [0006]     The following summary is intended to introduce the reader to the invention but not to define it. The invention may reside in any novel or inventive combination of apparatus elements or process steps found in any part of this document. An object of the invention is to improve on, or at least provide a useful alternative to the prior art. Other objects of the invention are to provide a process or membrane tank or a water treatment system or process.  
         [0007]     The present invention provides the advantage of a process or membrane tank with at least a collapsible portion. The tank may be manufactured from a flexible material and the entire tank may be collapsible.  
         [0008]     In one aspect, the invention provides an apparatus having a tank having at least a portion of its surface collapsible such that the tank can be configured in either a deployed position or a smaller stored position. A membrane module is located in the tank. The tank has a feed inlet and a permeate port in communication with the membrane module. When in the deployed position, water enters the inlet and flows through the membrane and out the permeate port in a filtration process. When filtration is no longer required, the tank can be collapsed for transport. The membrane module may remain in the tank when the tank is collapsed. For example, the membrane module may comprise hollow fiber membranes which may be rolled or folded with the tank. The ends of the membrane module may be held in the tank by connectors that facilitate collapsing the tank with the membrane module inside. The tank may have a retentate outlet for feed and bleed filtration or for filtration according to cycles of dead end filtration and tank deconcentration. The apparatus may also include an aerator and vent to permit gas scouring the membrane module. The aerator may be at least partially integral with the tank. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     In the accompanying drawings:  
         [0010]      FIG. 1A  is a perspective view of a first embodiment of a process tank according to the present invention.  
         [0011]      FIG. 1B  is an elevation view of the first embodiment.  
         [0012]      FIG. 2  is an exploded perspective view of a second embodiment of a process tank according to the present invention.  
         [0013]      FIG. 3  is an elevation of view of the second embodiment.  
         [0014]      FIG. 4  is an elevation view of a header according to the second embodiment.  
         [0015]      FIG. 5  is a partial exploded perspective view of the second embodiment showing the connection of a header to a support frame.  
         [0016]      FIG. 6  is a cross-sectional view of the header of  FIG. 4  showing an adaptor bracket for connecting a membrane to the header. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     An apparatus according to the embodiments described herein is suitable for use in the reverse osmosis water purification system disclosed in U.S. Pat. No. 6,120,688 (the &#39;688 Patent). Accordingly, the entire specification of the &#39;688 Patent is included by reference herein. The tank of the present invention may be used to replace the membrane tank disclosed in the &#39;688 Patent. Alternately, the invention may be used with other water treatment processes or systems.  
         [0018]      FIGS. 1A and 1B  show a process or membrane tank  10  according to a first embodiment of the present invention. The tank  10  includes a tank surface  12 . The tank surface  12  may be composed entirely or generally of a flexible material, such as urethane coated fabric. When filled with raw water, the tank surface  12  forms a pillow shape, as shown in  FIGS. 1A and 1B . Optionally, only a portion of the tank surface  12  may be composed of a flexible or collapsible material, and the remainder of the tank surface may be composed of a rigid material.  
         [0019]     A raw water feed inlet  14 , a raw water discharge outlet  16 , a permeate port  18 , and an air inlet  20  are all located on the tank surface  12 . Camlok fittings  22  are provided on each of the above ports  14 ,  16 ,  18 , and  20  to facilitate connection to corresponding hoses or lines (for example as described in the &#39;688 Patent).  
         [0020]     Continuing to refer to  FIGS. 1A and 1B , a membrane module  30  is located in the process tank  10 . The membrane module may include a plurality of hollow fiber membranes in the form of a rectangular bundle suspended between first and second headers  34   a  and  34   b , respectively. The rectangular bundle may be between four and twelve layers of membranes deep, and in the range of several tens of membranes wide. The membranes may have an outside diameter of 0.4 mm to 4.0 mm. The length of the membranes may be between 400 mm and 1800 mm. The membranes may have an average pore size in the microfiltration or ultrafiltration range, for example between 0.003 microns and 10 microns or between 0.02 microns and 1 micron. The membrane module may be as described in US Patent Publication No 2002/0179517 A1 which is incorporated herein in its entirety by this reference to it.  
         [0021]     A permeate cavity or conduit (not shown) is provided in the interior of second solid body  34   b . The permeate conduit transports permeate from the interior of the membranes  32  to permeate port  18 .  
         [0022]     Loop restraint anchors  36  are connected to the tank surface  12  at opposing ends of the tank  10 . Elastomeric bungee element restraints  38  are connected to the anchors  36  at one end and to slots  40  milled in the headers  34   a,b  at the other end to position the membrane module  30  in the tank  10 .  
         [0023]     Continuing to refer to  FIGS. 1A and 1B , a watertight zipper  50  is provided in the tank surface  12 . Preferably, the zipper  50  is located along the compression stress line of the tank surface  12 . Any suitable number of tension restraints  52  are connected to the tank surface  12  on either side of the zipper to reduce the tension force acting on the zipper  50 .  
         [0024]     An aerator  60  is located in the tank  10 . The aerator  60  is connected to the air inlet  20 . A number of grommet vents  62  are located in the aerator  60  to diffuse air or other gases supplied to the aerator  60  through air inlet  20  into the tank  10 . The aerator  60  may be composed of the same flexible material as the tank surface  12 .  
         [0025]     A flush gas vent  100  is provided in the tank surface  12  to permit gas introduced through the aerator membrane  60  to be released from the tank  10 . The gas vent  100  may be or operate as a one way valve allowing gas to escape, but not enter, the tank  10 .  
         [0026]     The operation of the process tank  10  according to the first embodiment will now be described with reference to  FIGS. 1A and 1B . The flexible material of the tank surface  12  permits the tank  10  to be collapsed to allow the tank  10  and other components of a water treatment system (for example a feed pump or hose, a permeate pump or siphon hose, an air pump if desired, and valves or control devices if desired) to be transported to a desired location by a vehicle, such as a HUMWV. At the desired location, the system (not shown) is assembled and connected to a source of raw water. Feed flow to the tank  10  may be by gravity or pump. Permeate may be drawn from the membrane module  30  by pump, gravity flow or siphon. Air for air scouring may be provided by air pump or blower if desired from time to time, continuously, intermittently or during or near relaxation, backwashing or deconcentration processes. Permeation may be by dead end filtration, feed and bleed filtration, or cycles of dead end filtration and deconcentration. Backwashing may be performed, if desired, by elevating a permeate tank to above the tank  10  or by pump from a permeate tank to permeate port  18 . Control may be by automatic or manual valves, turning pumps on or off, or altering the relative elevation of one or more of a feed tank, the tank  10  or a permeate tank.  
         [0027]     In one process, the raw water enters the tank  10  by pump or gravity from a flow source of surface or well water via the feed inlet  14  and fills the tank. When filled with raw water, the tank surface  12  expands to the deployed position and assumes the pillow shape.  
         [0028]     A suction may be applied to permeate port  18 , for example by pump or siphon, to draw the water into the interior of membranes  32 , in order to filter, for example microfilter or ultrafilter, the water. The permeate travels from the interior of the membranes  32  into the conduit in second header  34   b , and into permeate port  18 . Excess raw water may be discharged from discharge outlet  16  back into the raw water source, to the ground or for irrigation use.  
         [0029]     Air from an air source (not shown), such as an air blower, may be diffused into the tank  10  from grommet vents  62  of aerator  60 . The air may directly scrub the membranes  32  or operate to induce movement to water contacting the outside of membranes  32  to effect cleaning of the membranes  32 . Depending on the membranes  32  used, movement may be induced to the membranes  32 . In other words, percolation of the air may cause the membranes  32  to sway or move in the tank  10 , thereby effectively cleaning the membranes  32 .  
         [0030]     Flow of retentate through discharge outlet  16  may be controlled by sizing or valving the discharge outlet  16  to give a feed and bleed flow of  0  to 10% of the feed flow or to provide no bleed flow during some periods of time but drain at least a portion of the tank  10  rapidly from time to time to deconcentrate it. The gas vent  100  may have a restricted opening size so as to trap a cushion of gas under the gas vent  100  such that water will not escape the tank  10  even if feed or in tank  10  pressure temporarily or continuously exceeds the static head in the tank  10 . However, the tank  10  is not intended to be pressurized to a large degree, for example not more than 50% over ambient pressure.  
         [0031]      FIG. 2  shows a second embodiment of the present invention where a support frame  100  is provided to give the tank surface  12  a predetermined shape. The predetermined shape may be a box-like shape where the tank surface  12  includes a tank lid flap  101  which may be integral with the rest of the tank  10 . Like parts in this second embodiment will be assigned the same reference numbers as the corresponding parts in the first embodiment, and will not be further described.  
         [0032]     Referring to  FIG. 2 , the support frame  100  consists of a number of interconnectable support members  102  which are assembled into the support frame  100 . When the tank  10  is in the stored position, the support members  102  may be disassembled and stored in a more compact fashion. Preferably, the support members are 6061-T6 aluminum tubes having an outside diameter of 1″. Some of the support members  102  may include conventional male connections  104  and others may include female connections  106  to secure the support members  102  to each other by an interference fit.  
         [0033]     Discharge hose support  108  and feed hose support  110  may be provided on end pieces  112   a,    112   b,  respectively, of support members  102 .  
         [0034]     Support straps  114  are preferably connected to the exterior of tank surface  12  to attach the support frame  100  to the exterior of the tank surface  12 .  
         [0035]     Continuing to refer to  FIG. 2 , an integral aerator  116  is provided in a bottom portion  118  in the tank surface  12 . The aerator  116  is connected to air inlet  20 .  
         [0036]     Referring to  FIGS. 3-6 , the solid bodies  34   a,b  are preferably connected to stainless steel support bracket assemblies  35  which include inverted channel sections  200   a,    200   b.  The solid bodies  34   a,b  are supported on support frame  100  by the inverted channel sections  200   a,b  which engage the support frame  100 . While  FIGS. 3-6  show only one bracket assembly  35 , the other is supported on the support frame  100  in an identical fashion.  
         [0037]     Referring now to  FIGS. 2 and 6 , each end of the membrane  32  is connected through solid bodies  34   a,b  to bracket assemblies  35  by an adapter bracket  202 . This adapter bracket  202  slides into a slot (not shown) located in the solid bodies  34   a,b  and is connected to the solid bodies  34   a,b  for example by conventional screws, nuts, and washers.  
         [0038]     The operation of the second embodiment of the process tank  10  according to the present invention will now be described.  
         [0039]     The tank  10  is transported to the desired location in the collapsed position. In other words, the flexible tank surface  12  is collapsed or folded and the support frame  100  is disassembled into the individual support members  102 . During transport, a zipper  50  between the lid  101  and the remainder of the tank  10  is preferably closed to maintain an airtight seal between the tank flap lid  101  and the tank  100  in order to provide a moist environment which is desirable for the membrane  32 .  
         [0040]     Upon arrival at the desired location, the support frame  100  is assembled at the desired location by connecting the male connections  104  to female connection  106  of the various support members  102 .  
         [0041]     The tank  10  is positioned within the support frame  100 , and secured by the support straps  114 . In this manner, the support frame  100  forms an external support structure for the tank  100 . The zipper  50  is opened to provide access to the interior of the tank  10 . The headers  34   a,b  are connected to the bracket assemblies  35  and placed on the support frame  100  as described above.  
         [0042]     The tank  10  is filled up with water as described for the first embodiment above. The support frame  100  causes the tank  10  to assume the box-like shape when filled with raw water. The membrane  32  is suspended above the bottom of the tank  10  and below the surface of the raw water. The tank lid flap  101  remains either fully or partially open during operation to permit air introduced into the tank  10  by the aerator membrane  116  to vent. In other respects, the process tank  10  operates as described for the first embodiment above.  
         [0043]     While the present invention as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and thus, is representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described preferred embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims.