Polyphosphate and Ion Exchange Water Treatment Techniques Compared

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1 Polyphosphate and Ion Exchange Water Treatment Techniques Compared Hardness does not affect health so it is not an EPA regulated constituent but may be regulated by state or local health districts. The EPA does recognize hardness as a "secondary" contaminant and recommends water with a hardness level in excess of 3 grains per gallon (51 ppm) be treated. Hard water is the source of many household problems, it does impact quality of life and the pocket book. Typical hard water problems include hard to clean spots, scale build up, shortened appliance life, soap scum, your laundry to be grey, dingy, yellowing, rough and scratchy and more. In this paper I want to share with you similarities and differences between two water conditioning techniques that are very effective yet quite different in approach to resolving hard water problems, polyphosphate and ion exchange. Just to be clear, ion exchange is the process used by modern salt based softeners. First I want you to know both polyphosphate and ion exchange are well known and proven techniques to address hard water problems. Polyphosphate has been in use since at least the 1920's and modern ion exchange softeners have been used since the mid 1930's. Most are familiar to some degree with salt based ion exchange water softeners at the same time most are quite surprised at how effective polyphosphate is and especially surprised to learn polyphosphate is an alternative to salt softeners that has a 100 year old proven record of success. Even though both polyphosphate and ion exchange processes have proven very effective at conditioning hard water over the last few decades salt softeners have become the norm in residential applications. The ion exchange process is taught to students of residential water treatment in several nationally and internationally recognized industry organizations and by many of the major water treatment equipment manufacturing companies. Hard water conditioning using the ion exchange process is predictable, easily understood and results are measurable using a standard hardness test kit. Successful conditioning with polyphosphate on the other hand is not currently taught and is rarely mentioned as an effective conditioning option or as an alternative to ion exchange. Because conditioning with polyphosphate is not taught is in no way a reflection upon the effectiveness of using polyphosphate as an alternative to ion exchange. Polyphosphate has been in constant use since at least the 1920's mostly to condition water in high volume constant flow applications. One explanation as to why polyphosphate has not been commonly used in residential conditioning has been a control or dosing issue. Using polyphosphate in low and intermittent flow conditions typically found in residential and small business applications can make attaining desired results difficult. Polyphosphates are very powerful, it doesn't take much to do a lot of work so highly variable and intermittent flow rates can pose a very real challenge to process control. Phone Fax

2 Another potential dosing issue arises when water quality entering the treatment process is inconsistent. Typically, liquid phosphate pumping systems are set to treat a given quality of untreated water and so long as the water quality doesn t vary too much the process produces the desired effect. A problem arises if the untreated water quality varies enough to render the static pumping system settings ineffective. Changes in water quality can cause liquid polyphosphate pumping systems to be ineffective, essentially they fail in the face of variable water quality. The playing field has leveled over the last few years as significant advances in polyphosphates have been achieved. Modern chemistry and manufacturing techniques have produced forms of polyphosphate that are not only easy to use but easy to control in residential and small business applications. These advanced forms of polyphosphate eliminate dosing problems of the past making polyphosphates an alternative to ion exchange that is not only effective but easy to control and worthy of consideration. Ion exchange and polyphosphate are not mutually exclusive. Given the wide ranging capabilities of polyphosphates it is common to improve existing treatment systems that currently employ salt softeners by adding polyphosphate treatment. In the end, hard water conditioned with either polyphosphate or ion exchange improves quality of life and saves time and money but these systems condition the water in using very different techniques. No matter the technology you choose to use each has its pros and cons and it's important to understand what those are in order to help your customer choose the best solution for them. Comparison of Polyphosphate and Ion Exchange (Salt Softener) Technologies: POLYPHOSPHATE: Polyphosphate is derived from naturally occurring phosphorus rock and varying techniques used to manufacture polyphosphate create polyphosphates with unique properties. Polyphosphate treats hard water by a process that hides or holds the hardness in suspension. This process is known as sequestration or to sequester. To sequester undesirable contaminants like hardness means to isolate or hide away those contaminants. Think of it like this; hardness is like a popcorn ball; it sticks to everything it comes into contact with. Now, to prevent that popcorn ball from sticking to anything you'd wrap it or maybe put it into sandwich bag and though it is still a popcorn ball it can no longer stick to anything. By wrapping that popcorn ball or putting it into a baggie you've sequestered it, you've addressed the sticky problem without removing the sticky stuff. Sequestration of hardness is just like sequestering the sticky popcorn ball, the hard water problems are solved without removing the hardness. Because the hardness is sequestered it can no longer cause hard water Phone Fax

3 problems, it can't form scale, it can t leave hard water spots, soaps will suds and work better and all the benefits of softened water are achieved. Polyphosphate effectively softens the water and though sequestered minerals cannot cause the problems they would if left untreated they are still in the water, they are not removed. Because the minerals are not removed from the water we do not generally refer to water treated with polyphosphate as water that is softened rather we refer to it as water that is conditioned. When using a hardness test kit the conditioned water will show the same amount of hardness before and after treatment with polyphosphate. Just as the treatment is different you need a different kind of test to show it is working. There are very simple tests to show polyphosphate is sequestering hardness and conditioning the water. During the treatment process a very small amount of polyphosphate is added to the water. The US EPA sets limits to the amounts of many things added to the water for treatment and has determined the maximum allowable amount of polyphosphate that can be added to the water. It is advisable you choose a polyphosphate that meets your treatment needs and has been approved for use in drinking water by a third party such as NSF or WQA. Polyphosphate is added to water for conditioning and after time the polyphosphate will need to be replenished for effective treatment to continue. A few other things about modern polyphosphates worth noting: Polyphosphates play well with other water conditioning equipment and processes and can be used to enhance new or existing traditional salt softeners and other water conditioning systems. Many consider polyphosphates the "Multi Tool" of the water treatment world. There are specialty polyphosphates that can be used to treat a wide variety of water quality problems including; hard water, iron, manganese, low ph, silica and aggressive or corrosive water conditions. All this in a very simple easy to use form. NSF approval of your polyphosphate of choice is important. The NSF approval process helps assure consumers the polyphosphate they are using meets strict quality and safety standards for drinking water. ION EXCHANGE: Ion exchange is the technology used by salt based softeners. Salt softeners have at least two tanks, one for synthetic resin ion exchange beads and one for salt. Resin beads are derived from petrochemical plastics and are designed to have "exchange" sites and when fully charged or in the "ready" state, these exchange sites have salt attached. To understand how a softener works it helps to think of hardness, salt and exchange resin as playing a "dating game". Phone Fax

4 The dating game explained; In the ready state salt and resin are dating, they like each other, they're "holding hands". Then along comes hardness in the untreated water and now resin has a stronger attraction to this hardness than it does to the salt it is holding hands with so the resin lets go of the salt, it kicks it off and starts holding hands with hardness. This is the exchange of salt ions for hardness ions. This ion exchange happens many thousands of times as the softener resin beads release salt and load up with hardness. With each additional bit of hardness with which the resin holds hands there are fewer exchange sites available for holding more hardness. If nothing is done eventually all the resin exchange sites will be full of hardness and there will be no ability to hold or remove additional hardness. In this case hardness will simply pass through the softener. To prevent resin from completely filling its exchange sites and passing untreated hard water softeners must periodically regenerate. During the regeneration process concentrated salt from the brine or salt tank is introduced to the resin beads and when the resin sees this high concentration of salt it can't help but to have a stronger attraction to the salt than the hardness with which it's currently holding hands so the resin beads release the hardness that has been collected on the exchange sites and these sites are once again filled with salt. During the regeneration process concentrated salt, hardness and large volumes of water make up the waste water and are sent to the drain. After regeneration the resin is again in the ready state, it is ready to repeat the ion exchange process, the collection of hardness in exchange for salt until once again it sees concentrated salt at which point the beads will once again dump the hardness. An important aspect of the regeneration process is the fact it produces a salty waste water stream each time the softener regenerates. This salty waste stream causes its own set of issues that may need to be dealt with or may even prevent the ability to use a salt softener in some jurisdictions all together. This ion exchange process happens over and over again as long as there is salt in the salt tank and power to operate the softener control valve. IN THE END: Both polyphosphates and salt based ion exchange processes produce water where hardness mineral problems are eliminated. These problems include; Scale build up Hard to clean water spots Gray, dingy, yellowing, rough and scratchy laundry Soap scum on tubs, showers and sinks Shortened appliance life Increased cost to heat water Increased soap use Greater time and effort to clean and maintain the home or business Phone Fax

5 POINTS OF COMPARISON: Parameter Polyphosphate Salt Softener Equipment Cost Hundreds Thousands Installation time Required (installation not included in equipment cost) 1 hour 4+ hours Maintenance Cartridge Kit Salt, Maintenance Annual operating cost (supplies / materials only) $220/yr. ($18/mo.) Time to maintain/yr. 1/2 hour hours Cost to maintain/yr. at $20/hr. $10/yr. $300 $600/yr. Total cost to operate/yr. $231 $600 $1,050 $300 $450/yr. ($25 $38/mo.) Home delivery of salt extra. Physical Size (Integrated Cartridge Solutions) < two feet on wall 4 ft. x 2 ft. on ground and 5 or more ft. tall. Salt storage extra. System Drain for easy maintenance or winterization Waste Water Drain Required Water Wasted / Year None 10,000 gal. (weekly regeneration) No Power Required Salt Required Salt Used / Year None 1,170 pounds 30 bags Salt added to diet Treated water feels slippery Silent operation Not spot free treatment Spots easier to clean vs. untreated hard water Banned in some jurisdictions Dissolves / Removes existing hard scale build up in plumbing Soaps will form suds and not form a curdy precipitate or soap scum Appliances will operate more efficiently, cost less to maintain and last longer Laundry will be brighter, whiter and softer Not recommended for watering plants, lawns, and gardens Phone Fax