By Stan Barnes

Summary: One water treatment dealer explains the evolution of its move from deionization tanks to reverse osmosis systems. Both technologies are very viable in the marketplace for many of the reasons stated here.

When our company first began servicing the commercial, industrial and institutional markets in 1986, we had an occasional call for reverse osmosis (RO) units, but the total annual sales of deionized (DI) portable exchange tank and “on-site” DI systems (i.e. entire unit is permanently installed on site and regenerates on site) made the annual sales of RO installations—and preventative maintenance of those units—seem extremely small in comparison. For the most part, this was also the case for similar companies throughout the country. Well, that was then and this is now. RO systems of all sizes and shapes for all types of applications and gallon per minute (gpm) outputs have taken many industries by storm.

Nevertheless, the DI exchange tank business continues to be an excellent income producer for numerous local, regional and national water purification and filtration companies (while on-site DI systems sales have dropped dramatically). At least for now, the volume of annual DI exchange tank business is still growing, but not at the previous rate.

Flight of the RO
For most of these companies (including ours), the annual sales volume for design, installation and preventative maintenance of RO systems has now become the “tail wagging the dog.” In Marketing 101 terminology, the DI business is quickly becoming a maturing, slow growth market while ROs continue to evolve as a new and expanding, fast-growth market—even though ROs have been around for many years already.

For those who may not be familiar with the DI process, a simple explanation will be provided. In addition, while it won’t be discussed in this article, electrodeionization (EDI) is a modular “self-regenerating” process (vs. the standard DI exchange tank process or on-site DI process) that’s emerging in the marketplace as another fast-growing application for larger volume users of DI water and those needing higher purity levels of water than RO systems can deliver. Like RO systems, EDI carries an expensive initial investment so it won’t be for everybody.

In defense of DI
Simply put, deionization is a process utilizing specially manufactured ion exchange synthetic resins that remove virtually all the ionic material from water. These tiny resins appear similar to those used in water softeners, but they aren’t the same. Depending on the synergistic combination of the resins and the pre-filtering process, you can theoretically remove 99.9 percent of the conductive ions. The DI process, however, doesn’t guarantee total removal of organic material, viruses or bacteria, except through “accidental trapping” in the resins that are made from a strong anion base.

The two resins most commonly used in both on-site and DI exchange tank systems are cation (which remove positively charged ions such as calcium, magnesium, iron and radium) and anion (which remove negatively-charged ions such as carbonates, sulfates, nitrates and arsenate). These resins are available in different grades and types and they can be kept separate or combined in a mixed-bed formula to achieve a more powerful, synergistic, ion removal effect. These resins are placed into tanks that range from a few inches high and wide to tanks that are many feet high and wide (especially on-site DI systems).

Some drawbacks
One of the limitations to both DI processes is the resins have a limited capacity for ion exchange and must be regenerated upon exhaustion (or when a conductivity monitor, set at a specific purity level, provides an alarm). Another limitation is, in the regeneration process, hydrochloric acids are used to regenerate cation resins, and sodium hydroxide (or caustic soda) is used to regenerate anion resins. This process must be performed in a carefully controlled environment because of the use of hazardous chemicals as well as waste management needs and restrictions.

Some on-site DI systems can be more cost effective than the DI exchange tank process, but they’re still a real aggravation for most maintenance people to operate while presenting an environmental concern, too. It’s been our experience, when given a choice, maintenance personnel would opt to go with someone else performing the regeneration process—or, better yet, having an RO to replace this process altogether.

One more item to point out here is many of the commercial/industrial applications for RO installations do require a higher level of water purity than an RO can produce alone. In this case, we design mixed bed DI tanks (i.e., cation and anion resins mixed) or their equivalent EDI systems as a “polisher” downstream of the RO purified water output. So unless an RO manufacturer invents a system that can meet this higher purity demand, there will always be a place for the DI process.

Proving its worth
As stated in the beginning, when this dealership first got into the water purification and filtration business, the applications of professional RO systems seemed very limited but promising. There had been many horror stories about the unreliability and frequent breakdowns of these units along with the initial costs. These stories, whether substantiated or not, kept many companies from making a move to ROs. Today, name brand RO units and the technology of “two-pass” (or double-pass)  RO systems delivering outstanding track records have overcome these sales obstacles.

ROs are purifying water for parts cleaning, paint lines, chemical production, hemodialysis, drug manufacturing, food production of all kinds, extremely high PSI saws that cut everything from wood panels to cookies, tool and die machines, grinders, laboratory use, etc. Yet, there are new RO applications out there right now unbeknownst to us and many more on the horizon.

Why this incredible turn of events in RO applications and sales? There are four major reasons—the cost effectiveness with excellent pay-back schedules, usually under three years or better when comparing with either DI exchange tank systems or “on-site” DI systems; the user friendliness of daily operation and the hassle-free maintenance program that’s also cost effective; the reliability of a system when a proven, name brand unit is designed, installed and maintained properly; and the safe, environmental-friendly, no chemical-use process.

It will be a long time before RO units move into a mature market and thereby slow down in total annual sales worldwide. Why? Because new applications for ROs continue to appear on the scene every day. Plus, more and more DI clients are making the change to modernize their plant water purification needs with one or more RO units while the leading manufacturers of ROs keep improving their performance and reliability.

If you’re presently working with DI exchange tanks or on-site DI systems and you’re willing to take a realistic look at both the hard and soft costs, regardless of the application, the question isn’t whether you should go with an RO—but how soon.

About the author
Stan Barnes is marketing director of Flier’s Quality Water Systems Inc. and Flier’s Underground Sprinkling Systems, of Grand Rapids, Mich., which he joined in 1999. In addition, Barnes performs sales duties along with two other people for Flier’s Quality Water. He received a bachelor’s degree from the University of Missouri in communications in 1965 and worked in broadcasting and audio visual production before starting his own national business and sales consulting firm in 1983. He can be reached at (800) 898-5525 or website:


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