Abstract:
A water treatment system includes a weak acid cation resin where a portion of the feed water is exposed to the resin and then blended with untreated feed water to produce a stream of water with reduced mineral scaling and potential. Feed water is split into a first fluid stream, fed to a bypass conduit and a second fluid stream that is conveyed through a weak acid cation treatment bed. After passing through the bed, the treated fluid is combined with the bypass fluid stream to produce a blended feed water at the outlet. The ratio of the bypass fluid stream and treated fluid stream is a function of pH and L.S.I. A controller and associated sensors may control the relative flow rates between the bypass fluid stream and the treated stream to maintain a predetermined water parameter such pH, L.S.I., etc. within a predetermined range.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/357,218, filed Jun. 22, 2010, the entirety of which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention is drawn to the area of water treatment, more specifically to the reduction of mineral scaling potential from feed waters for heated appliances in residential and commercial applications. 
       BACKGROUND OF INVENTION 
       [0003]    The scaling potential of any given water is dependent upon complex chemical and physical interactions of the various constituents dissolved therein. Scaling of water bearing appliances specifically those which employ heat as part of their function typically manifests itself by a hard incrustation comprised primarily of calcium carbonate (CaCO 3 ). This compound is formed by the following chemical reaction: 
         [0000]      Ca(HCO 3 ) 2 +heat→CaCO 3 ↓+CO 2 +H 2 O
 
         [0000]    It usually occurs directly on heat transfer surfaces resulting in increased energy consumption, failure of the heating element, or plugging of conduits and orifices. There are many methods known in the art to eliminate or inhibit this reaction. Perhaps the most well known and practiced treatment technique is ion exchange water softening. 
         [0004]    The formation of calcium carbonate particles follows a stepwise progression which includes the following elements: 
         [0005]    1) Saturation with respect to calcium; 
         [0006]    2) A shift in the alkalinity equilibrium to favor the formation of the carbonate ion; 
         [0007]    3) Nucleation; and 
         [0008]    4) Particle formation 
         [0009]    It is well known in the art that when operated in the hydrogen form, a weak acid cation resin removes cations that are associated with alkalinity. The degree of removal and ultimate working capacity of the media is dependent primarily upon the Hardness: Alkalinity ratio (H/A), flow rate and temperature. Chemically the process can be depicted as follows: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    Carbonic Acid readily disassociates to water and carbon dioxide. 
         [0000]      H 2 CO 3           H 2 O+CO 2    
         [0010]    The changes that occur during this process have the effect of reducing the Calcium content of the water, shifting the carbonate, bicarbonate, carbonic acid equilibrium to favor the CO 2  species, and lowering the pH. Generally these changes can be quantified in a predictable manner. In order to utilize this information and apply it in the treatment of water a number of “indices” have been developed to predict the tendency of a particular water to form a Calcium Carbonate scale. These have been collectively referred to as Calcium Carbonate Saturation Indices. Among the most popular are: The Langelier Saturation Index (LSI), the Ryzner Stability Index (RSI), the Puckorius Scale Index (PSI), and the Calcium Carbonate Precipitation Potential (CCPD). All are based on determining the equilibrium state of the water in question. In general: Water that is oversaturated with respect to Calcium Carbonate will tend to precipitate CaCO 3 . Water that is under-saturated with respect to Calcium Carbonate will tend to dissolve CaCO 3 . Water in equilibrium with Calcium Carbonate will have neither CaCO 3  precipitating or dissolving tendencies. These models are far from perfect, however they do provide a means to gauge the effect of changing water chemistry in order to achieve a desired finished water quality. An example of one such index and its significance is shown below: 
       Langelier Saturation Index (LSI) 
       [0011]    LSI=pH−pHs 
         [0012]    Where: 
         [0013]    pH=The measured pH of the water 
         [0014]    pHs=The pH at saturation and is defined as: 
         [0015]    pHs=(9.3+A+B)−(C+D) 
         [0016]    Where: 
         [0017]    A=(Log 10 [TMS]−1)/10 
         [0018]    B= − 13.12×Log 10 (° C.+273)+34.55 
         [0019]    C=Log 10 [Ca +2  as CaCO 3 ]−0.4 
         [0020]    D=Log 10 [Alkalinity as CaCO 3 ] 
       Significance 
       [0000]    
       
         
           
             LSI&gt;0—Water is supersaturated and tends to precipitate a scale layer of CaCO 3    
             LSI=0—Water is in equilibrium with CaCO 3 ; a scale layer of CaCO3 is neither precipitated nor dissolved 
             LSI&lt;0—Water is under-saturated, tends to dissolve solid CaCO 3    
           
         
       
     
         [0024]    For over 50 years, water softeners have been used in residential and commercial applications to remove or reduce the hardness (dissolved Ca and Mg) in the water. This produced the benefit of eliminating or reducing scale formation in water heaters and appliances, eliminating or reducing soap scum formation which allows for more efficient use of soaps and detergents, thereby simplifying cleaning tasks in the home, in the laundry and in personal grooming. The hardness removal or reduction has been historically provided by water treatment systems that utilized ion exchange technology. U.S. Pat. Nos. 4,337,153 and 5,300,230 describe systems that are typical of many that have been applied to this technology over the years. In general, an ion exchange water softener removes dissolved Calcium and Magnesium ions from the water and exchanges them for equivalent number of Sodium or Potassium ions. Sodium and Potassium ions do not form the same detrimental types of scale and scum as do hardness ions. Once an ion exchange system has removed a predetermined quantity of Calcium and Magnesium, it can no longer remove any more hardness and has reached its capacity. To allow it to continue to remove hardness it must be regenerated by introducing excess sodium or potassium ions to drive off the removed hardness ions. This process produces a discharge waste that includes not only the removed hardness ions but also excess sodium or potassium ions. This discharge also includes the chloride salts of these ions and is generally called a “brine” waste. Using this process, these products have provided home and business owners the benefits of soft water for years, efficiently and effectively. 
         [0025]    Predominantly over the last decade, concerns over the brine discharge have begun to develop. These are based on the potential for these discharged brine wastes to eventually end up in our waterways, rivers, lakes etc and also in the discharges from waste water treatment plants. The position held by some is that these brine wastes cause an elevated chloride and or sodium level in either the waterways or the wastewater treatment plant thereby making those waters less desirable for their intended uses such as recycling and /or crop irrigation. These issues have produced legislation that in some parts of the country have outlawed the use of ion exchange water softeners. 
         [0026]    One effective means of continuing to provide soft water to a home or business even in these restricted areas is to provide an ion exchange system but to perform the regeneration in another location so that there is no local waste brine discharge. In those cases, the tanks would be removed and taken to a facility where a dedicated waste pipe can take the waste brine discharge to an acceptable location such as the ocean or controlled evaporation ponds etc. While this is possible and is being effectively applied today, the home or business owner is inconvenienced by the necessity of having to open their home or business to service people on a frequent basis and the movement of the somewhat bulky tanks in and out of the home or business is difficult, time consuming, and can cause possible property damage. 
         [0027]    Alternatives to sodium or potassium chloride regenerants have been proposed. For example, Kunin et al, U.S. Pat. No. 6,340,712 teaches a solution for the regeneration of a Strong Acid Cation Exchange Resin comprised of potassium acetate, or potassium formate with citric acid and octyl phenol ethoxylate. Similarly, Cole, U.S. Pat. No. 4,298,477 employs an ionizable salt of morpholine. Both of these alternatives do not lend themselves as a comparable substitute for residential or commercial applications in terms of cost, availability or use. 
         [0028]    Additionally, many non-ion exchange based systems or devices have been developed. U.S. Pat. Nos. 4,299,700 and 4,235,698 are examples of technologies presented to provide home and business owners with alternatives to ion exchange water softening. The results produced by these and many other such devices are questionable and reports vary widely about their effectiveness. In any case they claim to provide some degree of scale reduction or prevention and at least some degree of other soft water benefits such as use of less soaps, easier household cleaning etc. These alternative systems or devices utilize a wide variety of technologies including magnetic fields, electromagnetic fields, template assisted nano crystal formation, and others. It should also be noted that using industry accepted water testing methods (Standard Methods for the Examination of Water and Wastewater) none of these devices produces a measurable difference in the water chemistry make up after processing. 
         [0029]    It has also been known for years that there are alternative ion exchange systems that can remove hardness. U.S. Pat. Nos. 4,235,715; 3,458,438; 3,423,311; 2,807,582, 6,746,609; and 7,632,412 show examples of systems where a weak acid cation (WAC) resin can be used to remove hardness and alkalinity in the water. It should be noted that the application of these types of resins have been predominately industrial in nature, i.e. applicable for high pressure Boiler feed water and Open Recirculating Cooling Tower Systems. Additionally they consist of multiple process steps, are designed for complete hardness removal, employ a decarbonation step, and are designed as a regenerable system. Therefore, a need exists for an efficient, simple and cost effective method of reducing scale in residential and commercial applications. 
       SUMMARY OF THE INVENTION 
       [0030]    What is provided is a water treatment system and method including weak acid cation resin where a portion of the water that is desired to be treated (feed water) is exposed to a weak acid cation resin and then blended with the feed water to produce a stream of water with a balanced water chemistry sufficient to reduce the mineral scaling potential. 
         [0031]    According to one embodiment of the invention, a method is disclosed which includes the steps of providing an inlet for receiving feed water, conveying a portion of the feed water to an inlet to a weak acid cation resin and bypassing the remaining portion of the feed water directly to an outlet. After passing through the weak acid cation resin, the treated feed water stream is recombined with the bypassed fluid stream, thereby delivering a blended feed water to the outlet. The amount of feed water delivered to the weak acid resin is adjusted in order to arrive at a predetermined Langelier Saturation Index (L.S.I.). The preferred L.S.I. range for the feed water at the outlet is−0.6 to−1.4. 
         [0032]    According to a further feature of the invention, the CO2 content of the blended feed water delivered to the outlet is allowed to increase to a level that is greater than the CO2 content of the feed water received at the inlet. In a more preferred embodiment, the CO2 content of the blended feed water is at least twice the CO2 content of the incoming feed water. 
         [0033]    According to an additional feature of the invention, the portion of the feed water fed to the weak acid cation resin is preferably fed in a downflow direction. Alternately, the feed water to be treated is conveyed in the upflow direction and the weak acid cation resin comprises a fluidized bed. 
         [0034]    According to another embodiment, a water treatment apparatus and method are disclosed which provides a feed water inlet for delivering water to a main feed conduit. A bypass conduit and branch conduit communicate with the main feed conduit. The branch conduit communicates a portion of the feed water from the main conduit to a treatment tank containing a weak acid cation resin. The bypass conduit bypasses the other portion of the feed water around the treatment tank. The feed water in the bypass conduit and the treated feed water leaving the weak acid cation resin are recombined and delivered to an outlet. According to a feature of this embodiment, the ratio of untreated feed water to treated water at the outlet is a function of the pH of the blended water at the outlet. 
         [0035]    According to a feature of this embodiment, a first control valve in the bypass conduit controls the flow rate of untreated feed water around the treatment tank and a second flow control valve controls the rate of flow of feed water to be treated by the weak acid cation tank. 
         [0036]    According to a further feature, the control valves are adjustable and are preferably motor driven. 
         [0037]    According to a further feature, a pH sensor is used to sense the pH at the outlet and a controller responsive to the sensor operates the first and second flow control valves in order to provide a blended feed water having a predetermined pH. 
         [0038]    In a more preferred embodiment, the pressure of feed water at the inlet and blended water at the outlet is monitored by pressure sensors and the controller, in response to the pressure sensors, controls the degree of opening in the first and second flow control valves. 
         [0039]    According to one preferred method for reducing the mineral scaling potential in feed water for a heated appliance, the following steps are disclosed. The L.S.I. of the available feed water is first determined. An inlet is provided for receiving the inlet feed water stream and valving is used to split the feed water inlet stream into a bypass inlet stream a stream to be treated. The stream to be treated is conveyed to a weak acid cation resin to produce a treated fluid stream. The treated fluid stream is combined with the bypass fluid stream to produce a blended feed water stream that is conveyed to an outlet. A parameter such as flow rate, pH or L.S.I. of the blended water stream is monitored and this information is used to adjust the valving to maintain a constant ratio between the bypass inlet stream and the stream to be created so that a predetermined L.S.I. is maintained at the outlet. Alternately, the ratio between the treated and bypass fluid streams are adjusted so that a predetermined L.S.I. is maintained for the water after it is heated by the heating appliance. 
         [0040]    In the preferred method, the L.S.I. range for the blended feed water at the outlet is−0.6 to−1.4. Alternately, the L.S.I. range for the feed water heated by the appliance is 0 to CO−0.75. 
         [0041]    In the exemplary embodiment of the invention, the CO2 level in the blended feed water at the outlet is greater than the CO content of the incoming feed water. Unlike the prior art, the present invention utilizes the increased CO2 content of the blended feed water to an advantage. 
         [0042]    Accordingly, it is the object of the present invention to provide a simpler and more efficient process for the control of scaling potential than that of the prior art. 
         [0043]    Additional features of the invention will become apparent and a fuller understanding obtained by reading the following detailed description made in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0044]    The foregoing and other features and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which: 
           [0045]      FIG. 1  is a schematic illustration of a treatment system and associated control for treating feed water prior to being delivered to a hot water heater or other appliance; 
           [0046]      FIG. 2  illustrates another embodiment of a treatment system for pre-treating a portion of feed water being delivered to a hot water heater or other appliance; and, 
           [0047]      FIG. 3  illustrates a third embodiment of a treatment system and control. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0048]    A water treatment method of the present invention in which a portion of the feed water to a heated appliance is side streamed and passed through a weak acid cation exchange resin in the hydrogen form. The effect of which is a reduction of a portion of the hardness bearing mineral content, an equilibrium shift of the alkalinity constituents to favor the formation and retention of dissolved carbon dioxide, and a subsequent lowering of the pH. 
         [0049]    There exists several commercially available resins suited for such a purpose, such as Purolite 107E, a macroporous, acrylic, carboxylic resin available from The Purolite Company, Bala Cynwyd, Pa.; or Dowex MAC-3 available from The DOW Chemical Company, Midland Mich. 
         [0050]    In order to achieve the desired water chemistry adjustment, the water is then blended in appropriate proportions or ratios by devices known to those skilled in the art. There are several methods that can be used to control the ratio in the blending process of the feed water to the WAC processed water. A key component of the control strategy is the water chemistry of the feed water. Depending on the type of control scheme used, this data, at a minimum will be used to determine if the water treatment apparatus is being applied within its working design parameters, or in a different control scheme, it can be used to set the actual mix ratio and to predict the useful life of the WAC resin in the system. It should also be understood that measurable benefits can be achieved over what may be a broad range of water chemistry adjustments, and that the method of control chosen can affect the range of adjustment. 
         [0051]    Freshly regenerated WAC in the hydrogen form can produce an effluent water pH in the 3 to 4 range. This low level pH could harm household appliances, plumbing, irritate skin etc, so there will need to be some fail safe control function added to any control scheme designed for this application. Anywhere a valve is positioned in the plumbing where a malfunction could alter the ratio of flow between the WAC tank and the feed water bypass producing a mix too low in pH there will need to be a means included to stop the flow through the WAC tank and alarming the homeowner that a service call is required. 
         [0052]    It should be understood that the functionality or effectiveness of the WAC resin bed will change over time as it is exposed to the feed water causing gradual depletion of the resin&#39;s capacity and kinetics, and therefore its ability to affect the blended water chemistry will also change. This happens because as the weak acid sites on the resin become occupied with divalent cations like Calcium and Magnesium through increasing contact with the feed water, there are less “new” or fresh sites available to provide the desired ion exchange. Therefore the feed water can pass through the WAC and have a greater chance of not making contact with a fresh ion exchange site, thereby allowing some of the water to leave the bed unaffected by the resin contact. Depending on the range of water chemistry adjustment desired, this change in the resin bed will require that whatever control scheme is chosen take this into account in its method of controlling the blend or mix. 
         [0053]      FIG. 1  illustrates an apparatus constructed in accordance with one embodiment of the invention. The apparatus is used to pre-treat feed water prior to being received by a hot water heater or other appliance. The system includes a tank  10  containing a weak acid cation resin through which a feed water stream is conveyed in order to pre-treat that water stream. The treated water stream is then recombined with the main water stream before being delivered to the hot water heater or other appliance. In particular, a source of feed water is connected to a main feed conduit  26 . The conduit  26  communicates with a bypass conduit  26   b  that includes a flow control valve  28  which may be a motor driven, adjustable valve. A WAC tank feed or branch passage  30 , including another flow control valve  32  which may also be a motorized adjustable valve, communicates the passage  26  with an inlet to the weak acid cation tank  10 . After traveling through the cation tank  10 , the treated water exits the tank via conduit  34  and is recombined with the feed water in a combined feed water passage  26   a.  As a result, the water delivered to the hot water heater or other appliance is a mixture of feed water and water treated by the cation tank  10 . 
         [0054]    In order to control the mixing or blending of the feed water and treated water, a pH sensor  40  monitors the pH of the blended water stream. The pH sensor may comprise a conventional pH sensor and include an analog element  40   a  which serves as a sensor and an analog indicating transmitter  40   b  which may include a display. 
         [0055]    A pH range or set point would be chosen at the time of installation and that set point would be used to set up a typical feed-back loop to control the automated flow control valves  28 ,  32  on both the WAC tank feed passage  30  and the bypass around the WAC tank (via passage  26   b ). A control circuit forming part of a controller  44  would adjust the flow through the WAC tank  10  and the bypass  26   b  around the WAC tank to achieve the desired pH range. A typical proportional integral derivative (PID) control would be built in to the circuit design to minimize “hunting” or oscillating caused by rapid valve movement and the associated downstream pH result. Pressure sensors  46 ,  48  would be included in the feed water supply and down steam of the WAC tank to control the degree of opening in both the flow control valves  28 ,  32 . As a pressure drop is sensed by the feedback from both the sensors, the control  44  would open both the valves  28 ,  32  while keeping the same ratio of split stream. The pH control would coordinate with the pressure control to produce a mixed stream within the desired pH range, while still maintaining an acceptable pressure for the mixed streams intended use. For instance since the WAC system is being applied to the hot water feed in a home, the available water pressure in a shower is an important issue, as it not only might determine the flow in the shower, it could also affect the hot to cold water ratio blend which could cause problems in the shower. Those skilled in automated controls can envision numerous ways that this can be carried out using both off the shelf PLC controls or custom designed circuits. There are also many choices available for the pH probe  40 , pressure sensors  46 ,  48  and controller  44  as well as the automated valves  28 ,  32 . An advantage of the control scheme discussed in this section is that it will automatically adjust for the gradual depletion of the resin bed by using pH as its controlling function. 
         [0056]      FIG. 2  illustrates an alternate embodiment of the invention. In this embodiment, a source of feed water is connected to an inlet conduit  26 ′. A dual flow control valve  50  determines the portion of feed water that is fed to the feed water bypass passage  26   b ′ and the inlet conduit  30  of the weak acid cation tank. 
         [0057]    In this embodiment, the blending ratio would be set at the installation based on the knowledge of the feed water chemistry and the desired chemistry of the blended stream. In one scheme this could be done by choosing a ratio of orifices that would control the flow (volume of feed water) sent to either the WAC tank  10  or bypassed around it via passage  26   b ′. It should be noted that while the size (diameter) ratio of the orifices can be set, the choice of the actual size of the orifice will need to consider the pressure drop created by them just as in the control scheme discussed in  FIG. 1 . One method of overcoming such a problem might be to have the orifices adjust in size while keeping the constant ratio by using the total combined flow through WAC resin and bypass as a means of choosing orifice size. In the preferred embodiment, the dual flow control valve  50  maintains a constant flow of blended water to the hot water appliance by adjusting the flow control so that the ratio between the feed water bypassing the tank and the feed water flowing through the tank remains constant. This can be achieved by using a flow control adjustment device such as that disclosed and claimed in International Application PCT/US2011/032212, filed Apr. 13, 2011, which is hereby incorporated by reference. The rotational movement of such an adjusting valve could be supplied by a feedback loop from a flow meter  52  to a rotary solenoid or stepping motor  50   a  controlled by controller  44 ′. 
         [0058]    Finally,  FIG. 3  illustrates a simplified embodiment. In this control scheme, one fixed orifice flow control  56  on the split stream feed  30  leading to the WAC tank  10  on some water sources may provide enough control to allow an acceptable yet varying split stream ratio between the passages  26   b ″ and  30 , producing an altered water chemistry, yet never allowing the mixed stream pH (in passage  26   a ″) to drop into an unacceptable range. 
         [0059]    It should be noted that, in all three embodiments, the weak acid cation tank  10  must be either periodically regenerated using known regeneration methods or periodically replaced with a tank containing freshly regenerated resin. 
         [0060]    The following are examples of balancing water chemistry and scaling potential. 
       EXAMPLE 1 
       [0061]    An effluent stream of a Weak Cation Ion Exchange Resin (WAC) was blended in various proportions with a “Hard” water source, and the LSI derived. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                   
                   
                 Ca +2  as 
                 Alk. as 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Hard:WAC 
                 TDS 
                 ° C. 
                 CaCO 3   
                 CaCO 3   
                 A 
                 B 
                 C 
                 D 
                 pH 
                 pHs 
                 
                           
                 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 No Blend 
                 490 
                 21 
                 245 
                 264 
                 0.169 
                 2.16 
                 2.02 
                 2.42 
                 7.30 
                 7.19 
                 
                           
                 
               
               
                 5:1 
                 410 
                 21 
                 202.5 
                 208 
                 0.161 
                 2.16 
                 1.91 
                 2.32 
                 7.21 
                 7.39 
                 
                           
                 
               
               
                 4:1 
                 380 
                 21 
                 196.5 
                 208 
                 0.158 
                 2.16 
                 1.89 
                 2.32 
                 7.15 
                 7.41 
                 
                           
                 
               
               
                 3:1 
                 380 
                 21 
                 187.5 
                 188 
                 0.158 
                 2.16 
                 1.87 
                 2.27 
                 7.03 
                 7.48 
                 
                           
                 
               
               
                 2:1 
                 370 
                 21 
                 168.7 
                 172 
                 0.157 
                 2.16 
                 1.83 
                 2.23 
                 6.85 
                 7.56 
                 
                           
                 
               
               
                   
               
               
                             indicates data missing or illegible when filed 
               
             
          
         
       
     
         [0062]    Results indicate that an increased negative LSI is achieved as a function of increased blending and corresponding water chemistry changes. 
       EXAMPLE 2  
       [0063]    Three small residential water heaters were configured to accept water from one of three sources: 
         [0064]    1. Unit H—Hard Water only, no treatment (control) 
         [0065]    2. Unit Alk A—the same Hard Water as the control, blended at a ratio of 2:1 Hard : WAC effluent 
         [0066]    3. Unit Alk B—the same Hard Water as the control, blended at a ratio of 5.6:1 Hard : WAC effluent 
         [0067]    Each water heater tank was allowed to fill with its respective influent, reach operating temperature and then drain. This cycle was repeated 9 times per day for 28 days. During the course of operation, measurements of flow, pressure, volume throughput, and electrical usage were recorded. Samples of the feed water to the heater (In) and water exiting the heater after a 2 hr residence time (Out) were taken periodically and analyzed. A quantitative assessment of changes to the water chemistry (table 2) as well as scale formation and recovery from the system (table 2-A) was made. 
         [0000]    
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                 Hard 
                 Alk A 
                 Alk A 
                 Alk B 
                 Alk B 
               
               
                 Parameters 
                 Hard In 
                 Out 
                 2:1 In 
                 2:1 Out 
                 5.6:1 In 
                 5.6:1 Out 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Calcium as 
                 184 
                 185 
                 124 
                 124 
                 164 
                 168 
               
               
                 CaCO3 
               
               
                 TDS 
                 352 
                 369 
                 275 
                 286 
                 325 
                 334 
               
               
                 pH @ 20° C. 
                 7.1 
                 7.2 
                 6.4 
                 6.4 
                 6.8 
                 6.8 
               
               
                 Total 
                 249 
                 245 
                 162 
                 160 
                 213 
                 211 
               
               
                 Alkalinity 
               
               
                 Temperature 
                 63.7 
                 124.7 
                 65.2 
                 124.7 
                 63.7 
                 124.7 
               
               
                 (F.) 
               
               
                 LSI 
                 −0.32 
                 0.4 
                 −1.36 
                 −0.75 
                 −0.74 
                 −0.11 
               
               
                 CO2 mg/L 
                 39.5 
                 31 
                 129 
                 127 
                 67.5 
                 67 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2-A 
               
             
             
               
                   
               
               
                 Total Scale recovered from System 
               
             
          
           
               
                   
                   
                 Hard 
                 Alk A 2:1 
                 Alk B 5.6:1 
               
               
                   
                   
               
             
          
           
               
                   
                 Calcium as Ca (mg) 
                 2,798 
                 121 
                 511 
               
               
                   
                 Magnesium as Mg (mg) 
                 160 
                  50 
                 102 
               
               
                   
                 Total (mg) 
                 2,958 
                 171 
                 613 
               
               
                   
                 % Reduction 
                 — 
                  94.2% 
                  79.3% 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLE 3 
       [0068]    A similar test was run as that presented in Example 2. Differences included a slightly different Hard water influent, and 3:1 blending ratio. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
                   
                 HW 
                 Alk 3:1 
                 Alk 3:1 
               
               
                   
                 Parameters 
                 HW In 
                 Out 
                 In 
                 Out 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Calcium as CaCO3 
                 218 
                 219 
                 163 
                 170 
               
               
                   
                 TDS 
                 430 
                 436 
                 370 
                 377 
               
               
                   
                 pH @ 20° C. 
                 7.0 
                 7.0 
                 6.5 
                 6.5 
               
               
                   
                 Total Alkalinity 
                 265 
                 265 
                 192 
                 203 
               
               
                   
                 Temperature (F)  
                 64.8 
                 124.7  
                 64.9 
                 124.7 
               
               
                   
                 LSI 
                 −0.32 
                 0.3 
                 −1.08 
                 −0.42 
               
               
                   
                 CO2 mg/L 
                 53 
                 53 
                 121 
                 128 
               
               
                   
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 3A 
               
             
             
               
                   
               
               
                 Total Scale recovered from System 
               
             
          
           
               
                   
                   
                 Hard 
                 Alk 3:1 
               
               
                   
                   
               
             
          
           
               
                   
                 Calcium as Ca (mg) 
                 1,927 
                 217 
               
               
                   
                 Magnesium as Mg (mg) 
                 127 
                  33 
               
               
                   
                 Total (mg) 
                 2,054 
                 250 
               
               
                   
                 % Reduction 
                   
                  87.8% 
               
               
                   
                   
               
             
          
         
       
     
         [0069]    From the examples presented it can be seen that the present invention shows an improved process for reducing the scaling potential of water employed in this type of application. Specifically: 
         [0070]    1) It is not necessary to remove all of the “hardness” associated with the water in order to achieve a non, or reduced scaling condition. Furthermore, contrary to the prior art, in order for scale reduction to occur, it is necessary to chemically balance the influent water sufficiently so as to assure a zero to negative LSI value after the heating process. 
         [0071]    2) As can be seen from Tables 2 and 3, the relative amounts of CO2 in the blended waters were significantly elevated by the present invention. Without being bound to any particular theory, it is believed that it is neither necessary nor desirable to decarbonate the Weak Acid Cation effluent or blended feed water. Ideally the CO2 generated from the Weak Acid Cation will be left in the blended stream so as to achieve the desired chemical equilibrium in favor of the CO2 species. Additionally removal of CO2 would therefore require more of the treated water to be blended to achieve the desired scale potential reduction and subsequently reduce the usable capacity of the media. 
         [0072]    3) By treating only a portion of the feed water, the ion exchange resin&#39;s capacity can be maximized, resulting in greater volume throughput and therefore eliminates the need for onsite regeneration to make the process economically viable. The accompanying chart shows an Estimate of a Whole House Hot Water Treatment based on 1 ft 3  of media, a 3,900 gal throughput capacity and various blending ratios. 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Blend Ratio 
                 WAC eff. (gal)  
                   
               
               
                 Hard: WAC 
                 60 gal/day HW 
                 Days of Service 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 2:1 
                 20 
                 195 
               
               
                 3:1 
                 15 
                 260 
               
               
                 4:1 
                 12 
                 325 
               
               
                 5:1 
                 10 
                 390 
               
               
                 6:1 
                 8.6 
                 453 
               
               
                   
               
             
          
         
       
     
         [0073]    The water treatment method and system can be applied to any stream where improved scale control and partial softened water benefits are desired. However, as the life or capacity of the system will be directly proportional to the flow through it and therefore for an acceptable life in the resin bed between service exchanges, it is proposed to apply it only to the hot water supply in the home, or feed to several or one particular appliance in either a home or business. 
         [0074]    Although the invention has been described with a certain degree of particularity, it should be understood that those skilled in the art can make various changes to it without departing from the spirit or scope of the invention, as hereinafter claimed.