The most appealing aspect regarding ozone production is eliminating the maintenance of a chemical dosing pump and the routine batch preparation of chlorine, hydrogen peroxide or potassium permanganate solutions typically associated with conventional oxidation systems. A properly designed ozonation system is most definitely a powerful tool to have at your disposal in a severe problem-water market.
The following is an interview by Don Mounce, WC&P Executive Editor, with Gary Battenberg, Technical Director with Hague Quality Water International, relative to the issue of ozone and small-scale domestic systems.
WC&P: In the July 2008 issue, we published the first of a three-part series on ozone treatment by the Water Quality Association Ozone Task Force that covered areas ranging from the fundamental aspects of oxidation to calculating ozone generator capacity and the fundamental aspects of filtration.
I understand there have been many articles during the past twenty-five years that have promoted the use of ozone as a chemical-free approach to treating iron, manganese, hydrogen sulfide and a host of other issues that ozone appears to remediate very readily. As a contributing member of our Technical Review Committee, with significant experience in ozone technologies among others, how do you weigh in on the subject of ozone?
Battenberg: We currently do not offer ozone as a treatment option and we have no plans for the foreseeable future. Because we are a supplier to the water conditioning industry, we often counsel our dealers who work with ozone on how to configure our products with their ozone components to create a balanced system. My previous experience has proven to be a valuable asset in that regard.
However, eight years ago, I did build a prototype turnkey system for evaluation and cost analysis. The product functioned exceptionally well, but did not make it out of R&D due to poor sales projections.
WC&P: When did you first begin working with ozone and where was your first installation?
Battenberg: My career in water treatment began in 1982 and the first five years were spent learning the fundamentals of water conditioning and the proper application of treatment options we offered in our market. I was introduced to ozone in late 1987. My first real challenge came in 1988 in Poquoson, VA where we used ozone to clean up severe well water that was so bad the homeowner had been hauling water for the previous nine years.
Because the home was located in the tidewater area of the Chesapeake Bay, their water quality fluctuated daily with the rise and fall of the tide. This fact alone made treating this water like trying to hit a moving target.
Additionally, the septic system was adversely affected at times by severe weather conditions and we had to come up with a creative way to dispose of the regeneration waste from our system. This challenge water included heavy sand, iron, manganese, hydrogen sulfide, coliform bacteria and color.
WC&P: That sounds like it was a very daunting task. Was there any water treatment of the customer’s well at that time?
Battenberg: Yes, there was. But, it was a collection of failed attempts by several local companies to clean up the water. It was quite evident that each successive company ‘scabbed’ onto the previous company’s work in an attempt to fix their water.
WC&P: I would imagine that this homeowner was very leery of anyone associated with water treatment. How did you convince the homeowner to give you a chance to prove that you had the remedy for what appeared to be an impossible task?
Battenberg: I took the time to show them how the technology actually worked by demonstrating how each phase of our system progressively removed and/or treated the offending constituents in their water. Using readily available miniature vessels, I created a representative series of vessels including sand separation, simulated ozone injection with concentrated oxygen, contacting, conversion and softening for the working water in the home and then followed up with the RO water.
At the end of the small, pilot-scale presentation of the working water, I presented them with a glass of clear, odor-free water and asked, “How do you like your water now?” They were very impressed with our approach but still very skeptical of the reliability of our system. I explained that we had been working to develop this process for a year and offered a 90-day, full-money-back guarantee if they were not completely satisfied.
They explained that they were in the position of having to trust that someone had finally developed a system that would improve their water and their quality of life. So they accepted our recommendation and I can tell you that we didn’t have to refund their money.
WC&P: That sounds complicated. I gather that ozone is not a system in and of itself because you mentioned several additional treatment steps necessary to treat their water. But you mentioned using concentrated oxygen to simulate ozone for the demonstration…why would you do that?
Battenberg: In some of the more advanced ozone applications, an oxygen concentrator is used to generate up to 90 percent pure oxygen for feedstock to the ozone chambers. Pure oxygen alone exhibits a naturally high oxidation-reduction potential so we used it as a substitute for ozone. At that time small generators were virtually unheard of, so we improvised and were very successful in demonstrating the power of oxidation using oxygen.
WC&P: If oxygen is so effective, why use ozone at all?
Battenberg: Ozone increases the oxidation significantly while ensuring against the occurrence of microbial contamination. Where pathogens and other bacterial conditions exist in a water supply, the worst thing you can do is inject air into a water stream without a powerful oxidizer to maintain bacteriological control in the system. You would literally force-feed bacteria that are already present and quite possibly create other bacterial species from iron, manganese and the like. I have seen air injection installations where unfiltered ambient air was being transferred from an environment rich in airborne rodent waste permeating the surrounding area. Needless to say, the homeowners were less than pleased with the results of their investment.
WC&P: I understand there are two ways to produce ozone, through UV and corona discharge processes. How do these two processes compare?
Battenberg: Ozone generation utilizing UV lamps is a proven method and is still in use today for different types of applications. One notable application is for algae control for fishponds and the like. UV lamps used for ozone production typically operated in the 185nm wavelength, not the more recognizable 254nm associated with microbial control.
The disadvantages are that the UV lamps undergo a photochemical change over time, reducing the irradiance intensity and ozone production drops. If you have ever stood at a copy machine, you may have detected a slight sweet odor emanating from the machine: that is ozone being generated from the lamps used in the copy machine.
The early lamps used a mercury vapor and were changed to an inert gas tube to prevent potential mercury contamination if the lamp were to break. Since ambient air was used as the feedstock to the generator, this possibility presented severe risk to the user and the manufacturer. For a short time during this phase in small ozone generator design, the Giessler tube was available but very hard to obtain due to the low production volume from this small supplier. If the air preparation for these early generators was not maintained properly, nitric acid accumulation on the sleeves would cause arcing within the chamber, resulting in failure of the generator.
Corona discharge ozone generation has replaced most of the UV lamps for domestic ozone systems because of the smaller, more compact design of the electrode and dielectric. Ceramic or borosilicate glass tubes are used because the tolerances are easier to maintain and the ground-plane can be optimized for maximum output.
Low frequency CD (50-100 Hz) is more common because it is easier to dissipate the heat build-up, whereas the medium- and high-frequency designs require more sophisticated cooling with water, water/oil or Freon to dissipate the heat. The power supply for this type of generator was different from the ballast used to energize the UV lamps.
Early designs used center-tap transformers or lawn-mower coils for the power supply and small fans were used to draw air though the cabinet to reduce heat build-up. The CD generators are more rugged and dependable than the more fragile UV lamp type of generator.
WC&P: Is an ozone installation considerably more complex than conventional treatment equipment?
Battenberg: I don’t think so because, like any technology, once you fully understand the fundamentals and functional dynamics required to ensure consistently reliable performance, a practicing dealer can build a very happy customer base utilizing ozone. From my perspective, it is really nothing more than a super-aeration system that incorporates a powerful oxidizer for microbial control. The most appealing aspect regarding ozone production is eliminating the maintenance of a chemical dosing pump and the routine batch preparation of chlorine, hydrogen peroxide or potassium permanganate solutions typically associated with conventional oxidation systems. A properly designed ozonation system is most definitely a powerful tool to have at your disposal in a severe problem-water market.
WC&P: What do you mean by functional dynamics?
Battenberg: Most domestic and small commercial installations use a Venturi to draw ozone into the water stream. A thorough mix of water and ozone combined with sufficient contact time ensures that contaminants are fully converted and efficient removal is easily accomplished. Some ozone generator suppliers suggest merely placing a Venturi in the raw water supply line and using motive flow and pressure from the well pump and pressure tank to achieve injection.
In theory, there may be low enough back pressure against the Venturi for this type of application to work. The reality is that this configuration would only allow injection for the first one-third of the pump cycle with rapidly decreasing draw rate and contacting efficiency in the second third of the pump cycle.
Therefore, you can accurately surmise that there would be virtually no injection or contacting during the final third of the pump cycle. Untreated water would then migrate into the service plumbing and the customer would, of course, not be completely satisfied with the results.
WC&P: Is there a way to improve efficiency of injection and contacting?
Battenberg: Yes, in fact it is relatively simple by including a recirculation loop and pump. The key to functional dynamics is to control system pressure so there is at least a 50-percent differential across the Venturi at all times. Greater differential means more efficient mass transfer of ozone into water and more consistent performance of the system.
Contact time, the other half of functional dynamics, is critical in maintaining the efficiency of the oxidation and purification process and is achieved with an adequately sized contact tank. Some system configurations flatly ignore the long-accepted French standard of four-minute retention time.
In some instances complete oxidation and purification may occur with very brief contact, but I believe it’s too risky not to include a contact tank of sufficient volume to provide the four-minute retention time. No matter how complete the water analysis is, there may be contaminants in the challenge water that were not tested.
Some of these may create additional ozone demand and therefore it just makes sense to take full advantage of the power of ozone by giving it time to work as efficiently as possible. Water treatment specialists are equipped with a lot of power with ozone, so the best advice I can offer is to pay strict attention to the fundamentals.
WC&P: You mentioned previously a turnkey system. That suggests to me that most suppliers offer components for assembly by their water specialist customers. Are there any suppliers who manufacture turnkey systems like you mentioned earlier?
Battenberg: Yes—in fact, late in 1988, we received a flyer from our ozone generator supplier announcing a skid-mounted ozone system complete with generator, air dryer, injection/recirculation pump and contact chamber. The components were pre-plumbed and wired within the confines of the skid and fully tested at their works prior to shipment to ensure reliable performance. All we had to do was plumb in, plumb out, make a simple electrical connection and turn it on.
The advantage we immediately saw was the time saved in field-engineering the system ourselves. We simply had to interface our filtration with their ozone package and start up the system. Within two years, the company had developed a hypercontacting contact chamber that reduced the size of their previous tank from 42 to 18 gallons (159 to 68 liters).
This new hydraulic feature took ad- vantage of the inherent capability of the pump and flow switch that were standard components of our previous designs. The new hypercontacting design was very unique in that the contact chamber actually became part of the recirculation loop instead of just a contact tank.
Ozonated water would exit the hypercontactor at seven gallons per minute (26.49 L/m). If the demand in the home was only 2.5 gpm, the other 4.5 gpm (18.92 L/m) would automatically divert to the suction side of the injection pump and join the incoming raw water where it was re-ozonated along with the 2.5 gallons per minute (9.42 L/m) of makeup to replace the volume used.
An off-delay timer was added to allow the system to continue to recirculate for a short time after flow to the service plumbing ceased. The efficiency of this system provided the minimum four- minute retention requirement and later became the standard for other companies to model their systems.
The hyper-contacting chamber is different from the standard- contacting chamber because the water exits from the lowest point in the tank instead of the upper third. The water enters the tank from the pump discharge at approximately one-third the height of the side-shell and a vortech device directs the water toward the bottom of the tank at about a 22-degree angle.
The spinning effect created by the vortech device creates an inverted cone. Imagine a sink full of water after the drain plug has been pulled. As the water drains, there appears a small hollow area and you can hear the air being drawn in by the vortex created by the swirling water.
With this type of contactor design, the water volume is greater at the bottom of the tank so the discharge is located in the bottom one-fifth of the tank side-shell. The advantage here is the elimination of large air bubbles that sometimes are too great for the standard air vent to release.
WC&P: Are there many companies now that produce similar systems like the type you mentioned here?
Battenberg: In the late 1980s there were only two or three companies of which I was aware. Today, there are at least a dozen that produce a turnkey system and they all differ in design and principal of operation but fundamentally, they achieve the same result. All combined, there are now more than 50 suppliers that provide everything from small, specialty components to full turnkey systems with compact dimensions that can be easily transported and installed by one installer instead of two or three, like we did in the early days. The evolution of the domestic ozone system has been a wonder to watch grow and mature into the fine product segment it has become.
WC&P: Would you say that ozone has gained a solid foothold in the domestic market and will continue to build inroads into the conventional water treatment arena?
Battenberg: Without a doubt! Advances in generator technology and improved reliability of related products demonstrate the commitment of those companies dedicated to solving the most severe groundwater and some surface water conditions in North America. I believe ozone systems are destined to earn a permanent place alongside softeners and other conventional treatment products and will eventually be just as commonplace.
WC&P: Thank you for sharing your experience and insight with our readership, relative to better understanding of small- scale ozone systems and the advantages of the technology.
About the interviewee
Gary Battenberg is with Hague Quality Water International located near Columbus, OH, holding the position of Technical Director since 1997. He has over 26 years experience in the field of domestic, commercial and high-purity water treatment processes. Battenberg has worked in the areas of sales, service, design and manufacturing, utilizing filtration, ion exchange, UV sterilization, reverse osmosis and ozone technologies. Contact him at firstname.lastname@example.org