Patent Publication Number: US-2012031844-A1

Title: Flow-switch-controlled, zero waste reverse osmosis water treatment system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/370,146, filed on Aug. 3, 2010, which is herein incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to water treatment systems and, more particularly, to a flow switch controlled, zero waste reverse osmosis water treatment system. 
     BACKGROUND OF THE INVENTION 
     Reverse osmosis is a water filtration method that removes many types of large molecules and ions from a solution. Typically, reverse osmosis water filtration utilizes a semi-permeable membrane that has the ability to remove and reject a wide spectrum of impurities and contaminants from such solution. In such a method, a predetermined pressure is applied to the incoming water through the membrane. The membrane filters impurities and large molecules from the incoming water, leaving purified water on one side of the membrane and what is referred to as reject water on the other side. The impurities that cannot pass through the membrane may then be carried away in the reject water stream. 
     Around the world, household drinking water purification systems often employ a similar reverse osmosis process for improving water for drinking and cooking. Conventional systems for purifying water by the process of reverse osmosis (RO) produce, in addition to desired purified water, a considerable amount of reject water, also known as waste water or concentrate water. In known reverse-osmosis water purifying systems, this reject water, which is a by-product of the RO process, is customarily flushed down the drain of the residence, business or other building in which the reverse osmosis system is installed. 
     Notably, most known zero waste reverse osmosis water treatment systems are level driven, i.e., they are switched on when the purified water in an accumulator tank drops below a certain pressure level. In such systems, the concentrate or total dissolved solids (TDS) which would normally be flushed down the drain are input back into the closed water supply system until the water level in the accumulator tank reaches a predetermined high pressure level. This is undesirable because there is the potential for high pressure problems if the concentrate is presented to the water system when the system is closed and there is no water movement. Moreover, known zero waste systems return the reject or waste water to the hot water line, which can contribute to the build up of TDS in the hot water line, especially at the point where the connection is made. With such systems, there is also the potential for increased water pressure that is generated by the RO pressure booster pump. 
     In view of the problems associated with known reverse osmosis water treatment systems, there is a need for a zero waste reverse osmosis water treatment system that is demand driven and wherein the concentrate or reject water stream is diluted almost instantly such as to avoid any significant pressure or increasing TDS problems within the system. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, it is an object of the present invention to provide a water treatment system. 
     It is another object of the present invention to provide a flow switch controlled water treatment system. 
     It is another object of the present invention to provide a flow switch controlled reverse osmosis water treatment system. 
     It is another object of the present invention to provide a flow switch controlled reverse osmosis water treatment system having zero waste. 
     It is yet another object of the present invention to provide a zero waste reverse osmosis water treatment system that avoids potential high pressure buildup in the system associated with known systems. 
     It is another object of the present invention to provide a zero waste reverse osmosis water treatment system that instantly dilutes reject water. 
     It is another object of the present invention to provide a zero waste reverse osmosis water treatment system that only generates purified water when water is flowing through a building&#39;s water distribution system, i.e., when water is on demand. 
     It is another object of the present invention to provide a method of controlling reverse osmosis water production with a flow switch and a pressure switch combination. 
     It is another object of the present invention to provide a method of controlling any commercially available reverse osmosis system using the method of controlling reverse osmosis water production of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawing, wherein below: 
       The sole FIGURE is a schematic flow diagram of a zero waste reverse osmosis water treatment system in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The zero waste reverse osmosis water treatment system of the present invention, shown generally at  10 , includes a water source, such as a water main  12  or conduit coming from the street or well. In the preferred embodiment, the system  10  includes a pre-filter array  14  positioned upstream from the water source for the filtration of various impurities. For example, the pre-filter array may include a whole home sediment filter  16  for sediment filtration and/or a whole home carbon filter  18  for carbon filtration, such as those known in the art. The sediment filter  16  and carbon filter  18  function to remove any sediment and/or carbon in the water passing through the water main  12 . 
     Once the water passes through this optional pre-filter array  14 , it may be piped directly into a home or building to one or more utility/mains water outlets  19  through a main supply line/conduit  20  for use where purified water is not required, such as for showers, washing dishes and laundry. Alternatively, the water may be diverted from the main supply line  20  to a reverse osmosis parallel flowpath  21  by way of a RO line/conduit  22  for further purification. As shown, the reverse osmosis parallel flowpath  21  and, in particular the RO line  22 , contains the main components of the zero waste reverse osmosis water treatment system  10 , as discussed in detail below. In particular, the RO line  22  includes a ball valve  24  for selectively controlling a flow of water from the main supply line  20  through the RO line  22 , an inlet solenoid valve  26 , a check valve  28  and a booster pump  30 . An outlet of the booster pump  30  is in fluid communication with an inlet of a reverse osmosis element  32 . In the preferred embodiment, the reverse osmosis element  32  is a semi-permeable membrane that has the ability to remove and reject a wide spectrum of impurities and contaminants, such as those known in the art. The reverse osmosis element  32  includes two outlets, a first outlet fluidly coupled to a purified water line  34  and a second outlet fluidly coupled to a reject water line  36 . 
     The reject water line  36  includes a reverse osmosis reject flow control unit  38  a check valve  40  and a ball valve  42 . As will be readily appreciated, the check valve  40  prevents water flowing through main supply line  20 , to a house or building, from flowing backwards through the reject water line  36  when the reverse osmosis system is not in use. The reject water line  36  terminates at, and is in fluid communication with, the main supply line  20  such that reject water may be mixed with mains water to instantly dilute the reject water and the filtered impurities therein, as discussed below. 
     As also shown, the purified water line  34  is in fluid communication with a reverse osmosis accumulator tank  42 . As discussed below, the reverse osmosis accumulator tank  42  stores purified water that has passed through the reverse osmosis element  32 , where it can then be piped to a purified water outlet  43  (such as a faucet) for use on demand (such as for drinking water). The reverse osmosis accumulator tank  42  is configured with a pressure switch  44 , which provides the advantages discussed hereinafter. 
     Importantly, a flow switch  46  is positioned in the main supply line  20  and is electrically coupled to the inlet solenoid valve  26 , booster pump  30  and pressure switch  44  for controlling operation thereof and for controlling a flow of water through the system  10 . The flow switch  46  may be installed in the water main of a building, or in a sub water main in the case of a larger building. As discussed in detail below, the system  10  also preferably includes a sensor, not shown, which identifies when water is flowing in the main supply line  20 , caused by normal demand, for uses such as showers and laundry, i.e., main water flow as opposed to reverse osmosis/purified water flow. 
     As shown, the system  10  includes a parallel flow path  21  or side-stream flow, as noted above, where water is diverted from the main supply line  20  in the house or building for further filtration. Once filtration is achieved, the purified water is piped to the accumulator tank  42  and then to dedicated faucets  43  or other points of use in the house or building through a dedicated purified pipe system. The reject water stream that did not pass through the reverse osmosis element  32  as purified water is then piped back into the main supply  20  before or after the point of entry into the sediment and carbon filters  16 ,  18 , as hereinafter discussed. 
     Operation of the reverse osmosis water treatment system  10  will now be described with further reference to the drawing. In operation, utility water begins downstream of the flow switch  46  through the main supply line  20 . Upon detecting the flow of water through the main supply line  20 , the flow switch  46  energizes and sends power to the inlet solenoid valve  26  and reverse osmosis booster pump  30 . The inlet solenoid  26  is controlled to its open position such that water is diverted from the main supply line  20  to the RO line  22 . The booster pump  30  is actuated to increase the water pressure and flow through the RO line  22  and into the reverse osmosis element  32 . Essentially, the booster pump  30  serves to force water through the semi-permeable membrane of the reverse osmosis element  32 . 
     The reverse osmosis element  32  functions to remove impurities and contaminants from the water passing through the RO line  22  and divides the incoming water into two outlet streams, a reverse osmosis/purified water stream which is the diverted into the purified water line  34 , and a reject water stream (containing impurities and contaminants) which is diverted into the reject water line  36 . 
     The pressurized reject water stream flows through the reject water line  36  and through the reject flow control unit  38  and check valve  40 , and is returned to the flow of utility/mains water through the main supply line  20 . Importantly, this reject water stream is immediately diluted in the flow of utility water and the increased water pressure is immediately reduced to match the line pressure of the main supply line  20 . Conversely, the purified water steam in the purified water line  34  is routed to the reverse osmosis accumulator tank  42  for use on demand. 
     Importantly, once water flow through the main supply line  20  ceases, the flow switch  46  automatically de-energizes and power to the inlet solenoid valve  26  and the reverse osmosis booster pump  30  is interrupted, thus stopping the flow of water through the RO line  22  and stopping the reverse osmosis water purification process. 
     Preferably, the pressure switch  44  associated with the reverse osmosis accumulator tank  42  continuously or intermittingly monitors a level of purified water in the tank  42 . If the pressure switch  44  indicates that the reverse osmosis accumulator tank  42  is full, power to the inlet solenoid valve  26  will be interrupted such that the inlet solenoid valve  26  is controlled to its closed position, and the booster pump  30  will be shut off. 
     In the preferred embodiment, power to the inlet solenoid valve  26  and booster pump  30  may only be restored when the pressure switch  44  indicates that the purified water level in reverse osmosis accumulator tank  42  has fallen below a predetermined level and there is again water flow downstream of the flow switch  46 , such as when a utility outlet  19  is opened to initiate the flow of utility/mains water through main supply line  20 . 
     Importantly, reverse osmosis purified water production only takes place when the utility/mains water is being used in the home or building. That is, water is only diverted from the main supply line  20  to the RO line  22  for purification when other than purified water, i.e., utility/mains water, is being utilized. During purified water production, the reject water stream that did not pass through the membrane as purified water is returned to the water main or sub water main through the reject water line  36  while utility water is being used. The mechanisms of producing the reverse osmosis product and reject water streams only during water use, and returning the reject water stream to the water main only during water use, significantly reduces or eliminates any potential of the total dissolved solids significantly increasing at the reject line connection point back to the main supply line. In addition, the reverse osmosis water treatment method of the present invention also significantly reduces or eliminates any potential increase in water pressure, as purified and reject water streams are only being produced when there is an open discharge point somewhere downstream in the plumbing system, i.e., when someone in the house or building is utilizing mains/utility water, i.e., other than purified water. 
     As noted above, one of the advantages of the present invention is that purified water is generated only during water flow through the house or building; consequently, the reject water stream is diluted instantly by mixing it with the flow of water through the main supply line  20 . Accordingly, the present invention ensures that there is no issue with potential high pressure problems within the system. As will be readily appreciated from the above, the primary focus of the system is to only generate purified RO water when the water is flowing through the main supply line  20  and into a house/building. 
     As noted above, a sensor positioned in the main supply line  20  senses the fluid flow in the main supply line  20  and uses the signal generated by such sensor to initiate the diversion of the water from the main supply line  20  to the RO line  22  to initiate RO water production. Preferably, there may still be a water level sensor in the accumulator tank  42 , however, unlike prior art systems which generate RO water when the water level in the accumulator tank drops below a certain level, the system of the present invention only generates RO/purified water when the sensor senses water movement upstream from the accumulator tank  42 , such as in the main supply line  20 . Consequently, there cannot be a situation where the RO booster pump  30  is activated when there is no water flowing through the main supply line  20  and into a structure. 
     While there is the possibility that if only the RO/purified water stored in the accumulator tank  42  is used, i.e., mains/utility water is not used, the system can go dry, in the majority of instances there will be enough utility water use in a home or building throughout the day to support demand for RO/purified water production in a home or building while that utility water is being used. 
     In yet another embodiment, the present invention provides a method of controlling reverse osmosis water production with a flow switch and pressure switch, combined with the method of returning reverse osmosis reject water to be fully diluted by the use of utility water in the home or building to the water main in the house or building. In this embodiment, there may be a time delay included such that the pump runs for a pre-selected period of time after the water shuts off. 
     In yet another embodiment, the flow switch controlled, zero waste reverse osmosis water treatment system  10  disclosed above may be combined with any type of whole home or partial building filtration system known in the art to provide the added benefits inherent with the present invention, as described above, in addition to the known benefits of the various types of whole or partial home or business filtration systems. In connection with this, the flow switch controlled, zero waste reverse osmosis water treatment system  10  of the present invention may be retrofit with existing systems to provide the added advantages noted above. 
     While the invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various obvious changes may be made, and equivalents may be substituted for elements thereof, without departing from the essential scope of the present invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention includes all embodiments falling within the scope of the appended claims.