A Brief History of Ion Exchange Water Treatment
By Gary Battenberg
In 1850, agriculturalist Harry Stephen Meysey Thompson and chemist John Thomas Way observed that when a solution of ammonium sulfate was passed through a specific type of soil, the effluent solution contained calcium sulfate. This prompted a report to the Royal Agricultural Society of England detailing in their discovery that various minerals (called permutites) were discovered. From these humble beginnings, industrial water softening got its start.
In 1905 Germany, Dr. Robert Gans developed the first commercial scale hardness removal system utilizing a natural zeolite type of soil. In Moscow, Russia in 1910, the first commercial zeolite softening system was installed at an electric power generation plant. And in 1913, the first synthetic zeolite was marketed by Pfaudler Permutit, Inc. of New York, yielding much greater hardness removal than natural zeolites. From 1913 to 1938, water softening accounted for most water conditioning and it was not until 1936 that dissolved solids reduction was achieved using ion exchange. It is from these beginnings that our industry developed in this country and today, millions of cubic feet of a variety of ion exchange media are produced for water treatment purposes.
In the early 1920s, residential softeners were basically scaled-down versions of commercial and industrial systems. These softeners were very large (at 30 to 36 inches in diameter) due to the low capacity of the greensand exchange media and were only affordable by the very wealthy of the day. These softeners had to be regenerated manually, a process which required several hours to complete. In addition to their regular responsibilities, domestic servants were tasked with maintaining these systems. Then came the manufacture of gel zeolite (the commercial name for synthetic sodium alumino-silicate), which was much more stable than greensand. This development opened the door for a greater domestic household market because the media tanks were somewhat smaller and featured simplified controls for operation. Emmett Culligan developed his first control valve and started his own water treatment business in 1924. During the Depression, he started a dealership network and soon, Culligan became a household name. The upper middle class could then afford and enjoy the benefits of softened water in their homes. This greater market led to the advent of the water treatment division of home appliance retail establishments. Emmett Culligan was not alone when he pioneered the residential softener, however. Lynn Lindsay was an important part of the development process. He and Culligan were neighbors in Minneapolis, MN and partnered in the beginning. For more information concerning Culligan and Lindsay, see www.lindsayewsc.com/links/lin_eco_hist.htm.
In the early 1930s, portable exchange tanks or media sacks were made available on a monthly rental basis. The exhausted tanks or media sacks would be replaced by a tank or sack with freshly regenerated zeolite media and the exhausted media would be returned to a central regenerating plant where large batches of media would be regenerated at one time. Finally, the middle class could also afford and enjoy the benefits of soft water. In 1935, English chemists Basil Albert Adams and Eric Leighton Holmes introduced the first phenolic form of ion exchange resins. This phenolic-formaldehyde product could be modified to create either cation resin using sulfonic groups (strong base cation) or anion resin using amine groups (weak base anion). Together, these two new resins made it possible for the first time to demineralize water by ion exchange and the first commercial demineralizing plant was built in 1937. Between 1945 and 1947, extensive research was done and an organic polymer was discovered that led to the development of styrene-divinylbenzene. That ultimately was the breakthrough for present-day ion exchange technology. This polymer was a much stronger, more stable and less pH-sensitive material than the phenolic resins. These early advancements quickly evolved and development of ion-specific resins were produced that could target troublesome contaminants such as nitrate, sulfate, uranium, arsenic, tannin and many others that could create aesthetic and health related problems for domestic consumers. High-purity resins capable of reducing total dissolved solids are now used in the semi-conductor, pulse-power research and nuclear industries.
In the early days, softeners could treat a few hundred gallons of water using natural zeolite (greensand) and would require as much or more water to regenerate. Now, with our current high-capacity and fine-mesh resins, much smaller softeners can treat several thousand gallons of water and regenerate with as little as nine to 15 gallons of water and less than three pounds of salt. Instead of taking hours to regenerate, the newer systems can regenerate in as little as 12 minutes. These newer resins have applications in virtually every area of commercial, industrial and high-purity water treatment. Additionally, ultrafine mesh resins are used in the pharmaceutical industry. Have you ever taken an allergy capsule? Did you know that the medicine in that capsule is bonded to the ultrafine mesh resin? Your body takes in the medicine and the resin passes through as waste.
More advanced resins have appeared in the last decade that are functionalized with nano templates and developed to target specific contaminants like arsenic. They require properly filtered water only, require no regeneration and can treat many thousands of gallons of water before exhaustion. Add to these advanced ion exchange resins the new particle-bonded, impregnated and catalytic media that target specific contaminants and you have a water treatment media arsenal that will equip you with the means to be very effective in remediating water problems specific to your market.
Ion exchange technology has grown tremendously in the last 100 years. These technologies have found their way into many markets that have made life in America much more comfortable, relative to the ability to resolve water problems that at one time required laborious effort to treat. Once treated, that water could be used to manage domestic households, water livestock, improve milk production for dairies, high-quality feedstock, for power and steam plants and many other applications requiring effective water treatment. The next 100 years will hopefully produce even more advancements, like research currently under way for ion exchange membranes that are electrically regenerated, instead of using salt, which is typical of legacy and current water softeners. Like the early pioneers who helped to establish water treatment, there are new pioneers applying the experience of those who have come before, advancing those technologies to launch the latest ion exchange technology.