Abstract:
Many treatment systems remove virtually all minerals and other elements from the water, however a quantity of certain minerals and elements is necessary for good health and acceptable water taste. Therefore, a water treatment system is provided in which a portion of the input water bypasses the primary filtration and treatment components. The amount of that portion is selectively controlled so that a healthy level of minerals remains in the treated water, which still is extremely clean. An optional component can be included to reduce pathogens in the treated water.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to apparatus for treating water to remove chemicals and other impurities, and more particularly to ion separation systems, such as membrane separation apparatus. 
         [0005]    2. Description of the Related Art 
         [0006]    Many places in the world have very poor sources of potable water as the water contains contaminants or has an objectionable taste, odor and color, or a very high mineral content that is not healthy to drink. Various types of systems are employed to improve the water quality to provide clean and healthy water. “Clean” refers to an aesthetic property, where the water has a colorless appearance, no objectionable taste or odor and does not leave a residue or scum. “Healthy” refers to the composition of the water having a healthy level of minerals and acceptable levels of organics and metals with little or no chlorine or pathogens (e.g. protozoa, bacteria and viruses). 
         [0007]    One type of treatment system utilizes reverse osmosis (RO) to purify the water. Point of use reverse osmosis water treatment systems are located under a countertop or sink in a kitchen or adjacent another place at which purified water is desired to be provided. The typical system comprises a pre-filter that employs a conventional filter medium, that removes relatively large particles as all the water being treated passes through the medium. The water exits the pre-filter and enters a reverse osmosis unit. 
         [0008]    Reverse osmosis is a method that separates solutes from a solution by causing the solvent (such as water) to permeate a membrane by use of a pressure higher than the osmotic pressure. As water diffuses through the membrane, dissolved substances, such as salts, minerals and other contaminants are left behind so that the water that permeates the membrane has a lower concentration of dissolved substances. The remaining dissolved substances are flushed from the higher pressure side of the membrane through a restricted drain opening that helps maintain an increased pressure within the unit. The fluid from the drain opening may be sent to a sewer system or recycled through the water treatment system by a pump so that less water is wasted. 
         [0009]    The treated water exiting the reverse osmosis unit may pass through an optional post-filter to improve the taste of the water that is affected when the system is not used for a prolonged period of time. A tank may also be provided at the output of the treatment apparatus to store the purified water. When needed, the purified water is drawn from the tank through a faucet. 
         [0010]    A drawback of reverse osmosis is that is may be too effective in removing substantially all the minerals, such as calcium and magnesium, from the water. However, human consumption of certain minerals is necessary for good health, and many people believe it is important to have a healthy level of minerals in their drinking water. Also, many people believe that water with a moderate mineral content has a better taste than water with no minerals. As a consequence, the purified water from a reverse osmosis treatment system often is fed through a mineral bed to replenish the potable water with a healthy amount of desirable minerals. The mineral bed adds cost to the system and its storage vessel can be a source of bacteria. 
         [0011]    Therefore, it is desirable to provide a water treatment system that provides a source of both clean and healthy water that contains amount of desirable minerals for good health and taste. 
       SUMMARY OF THE INVENTION 
       [0012]    A water treatment system comprises a water inlet port for receiving water to be treated and a water outlet port through which treated water flows. An ion separation module is fluidly connected between the water inlet port and the water outlet port and removes particles from water that flows there through. A bypass flow branch is connected between the water inlet port and the water outlet port in parallel with the ion separation module. The bypass flow branch has an orifice restricts the flow of water and thereby determines how much of the total volume of water flowing through the water treatment system travels through the bypass flow branch. 
         [0013]    By allowing a portion of the water to travel around the ion separation module, some of the minerals in the source water remain in the treated water for health and taste reasons. The size of the orifice in the bypass flow branch controls the amount of those minerals. 
         [0014]    Optionally a pre-filter can be connected upstream of the ion separation module to remove relatively large particles from the water flow, thereby increasing the operating life of the ion separation module. Another option, a post-filter can be connected downstream of the ion separation module to improve the taste of the water which may be adversely affected when the system is unused for a prolonged period of time. The water flowing through the system also may pass through a sterilization module to eliminate pathogens. 
     
     
       DESCRIPTION OF THE OF THE DRAWINGS 
         [0015]      FIG. 1  is a schematic diagram of a water treatment system that has a reverse osmosis unit with a continuous partial flow bypass path; and 
           [0016]      FIG. 2  is schematic diagram of an alternative water treatment system according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    With initial reference to  FIG. 1 , a first water treatment system  10  comprises a pre-filter  12 , an ion separation module  14  and a post-filter  16  that are connected in series forming a primary flow branch  18  of the system. A bypass flow branch  20  is connected in parallel with the primary flow branch  18  and comprises a bypass filter  22  and a flow control orifice  24 . The two flow branches  18  and  20  are connected between a water inlet port  26  and a water outlet port  28 . 
         [0018]    The pre-filter  12  in the primary flow branch  18  includes a first container  30  having an inlet  32  adjacent an outer wall and a centrally located pre-filter outlet  34 . Within the container  30  is a pre-filter cartridge  36  with a conventional filter medium, such as a tubular body of a spun fiber material through which the water flows to trap relatively large particles. If the source water is relatively free of large particles, the pre-filter  12  may be eliminated. The water to be treated enters the inlet  32  flows through the pre-filter cartridge  36  to a central bore which communicates with the pre-filter outlet  34 . The pre-filter outlet  34  is connected by a conduit  40  to an inlet  42  of the ion separation module  14 . 
         [0019]    The ion separation module  14  has a standard ion separation membrane  46 , such as a reverse osmosis membrane or a nano-filtration membrane, within a second container  44 , thereby defining an outer chamber  48  and an inner chamber  50  that are separated by the membrane  46 . Alternatively, the ion separation module  14  may comprise an electrodialysis device, an electrodialysis reversal device, a distillation unit, or a capacitive deionization device. The inlet  42  for the ion separation module  14  opens into one end of the outer chamber  48 . A drain outlet  52  is located at the opposite end of the outer chamber  48  and is significantly smaller than the inlet  42 . The size differential between the inlet  42  and the outlet  52  creates a pressure differential between the outer and inner chambers  48  and  50 , which forces some of the water through the ion separation membrane  46  into the inner chamber  50  in a well known manner as in standard reverse osmosis systems. The drain outlet  52  is connected to a drain line  54  that either leads to a sewer system or may be recycled via a pump (not shown) to the water inlet port  26  of the treatment system, as is done in previous reverse osmosis water treatment systems for water conservation. 
         [0020]    The ion separation module  14  has a treated water outlet  56 , which is connected to an inlet  58  of the post-filter  16 . The post-filter  16  has a third container  60  within which a conventional tubular-shaped filter medium  62  is located. The filter medium  62  for the post-filter  16  can be similar to that used in the pre-filter  12  but able to trap smaller particles, or it may be another type, such as a sediment filtration medium or activated charcoal. The treated water from the ion separation module  14  flows through the post-filter medium  62  exiting that filter via an outlet  64 , which is connected to the water outlet port  28  of the first water treatment system  10 . Thus, highly purified water passes from the primary flow branch  18  to the water outlet port  28 . 
         [0021]    As noted previously, such highly purified water is devoid of minerals, which are beneficial to a person&#39;s health, and is relatively tasteless. As a result, the bypass flow branch  20  provides a fluid path parallel to the primary flow branch  18  so that some minerals in the source water reach the water outlet port  28 , thereby providing improved taste and beneficial minerals to the treated water. In particular, the water inlet port  26  for the first water treatment system  10  also is connected to an inlet  66  of a bypass filter  22 . The bypass filter contains a filter medium similar to that used in the pre-filter  12 . The bypass filter  22  has an outlet  70 , which is connected by the orifice  24  to the water outlet port  28  of the first water treatment system  10 . The size of the bypass orifice  24  is selected to determine the portion of the total water flow through the first water treatment system  10 , which passes through the bypass flow branch  20 . For example, when used where the feed water contains approximately twice the level of minerals that would be deemed to be healthy, the orifice would be set to allow about half of the feed water to enter the by-pass. 
         [0022]      FIG. 2  depicts a second water treatment system  100  according to the present invention. Here a water inlet port  102  is connected only to the pre-filter  104 , which has a similar construction to pre-filter  12  in  FIG. 1  and removes relatively large particles from the water flow. The pre-filter outlet  106  is connected to a primary flow branch  111  containing an ion separation module  110 , that has a membrane  112  such as a nano-filtration membrane or a reverse osmosis, for example. Specifically, the pre-filter outlet  106  is coupled to an inlet  108  which opens into one end of an outer chamber  114  of the ion separation module  110 . A restricted drain outlet  116  at the opposite end of the outer chamber  114  creates a pressure differential between the outer chamber and an inner chamber  115 . Thus, some of the water entering the outer chamber  114  is forced through the ion separation membrane  112  to a treated water outlet  117 . 
         [0023]    A bypass flow branch  124  is connected in parallel with that primary flow branch  111 . The bypass flow branch  124  includes a conduit  126  that couples the outlet  106  of the pre-filter  104  to a variable orifice  128 , such as provided by an adjustable valve. The variable orifice  128  allows a user to adjust the portion of the total flow through the second water treatment system  100  which passes through the bypass flow branch  124 . This controls the amount of minerals which are allowed to bypass the primary flow branch  111  for health and taste reasons. The terminus of the bypass flow branch  124  is connected to a conduit  119  coupled to the treated water outlet  117  of the ion separation module  110  thereby combining the water flows from the primary and bypass flow branches  111  and  124 . 
         [0024]    That combined water flow is applied to a sterilization module  118 , which may either treat the water flowing there through with light from an ultraviolet source or pass that water through a membrane that is capable of retaining pathogens. The sterilization module  118  eliminates pathogens from the water flow. The outlet  120  of the sterilization module  118  is coupled to the water outlet port  122  of the second water treatment system  100 . Alternatively, a post filter, similar to the post-filter  16 , may be inserted between the treated water outlet  117  of the ion separation module  110  and the inlet of the sterilization module  118 . 
         [0025]    It should be noted that the variable orifice  128  of  FIG. 2  can be used in place of the fixed orifice  24  in the first water treatment system  10  in  FIG. 1 . Similarly, a fixed orifice can be utilized instead of the variable orifice  128  in the second water treatment system  100 . In another variation, the sterilization module  118  can take the place of the post filter  16  in the first water treatment system  10  and the post-filter  16  can be employed in place of the sterilization module  118  in the second water treatment system  100 . 
         [0026]    The foregoing description was primarily directed to a preferred embodiment of the invention. Although some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.