Earlier this year, Water Technology and WaterTech e-News Daily™ conducted a survey to gauge reader interest and satisfaction in ultraviolet (UV) technology. The emergence of UV in water treatment has been met with approval and criticism. This article reviews the survey, which was completed by 256 people, some of the feedback we received and manufacturers’ insight.

According to our survey, when asked, “Have you sold more, less or about the same number of UV units over the past 12 months,” respondents offered the following:

  • More – 25 percent
  • Less – 15 percent
  • About the same – 26 percent
  • Question doesn’t apply – 35 percent.

Reader issues with expert insight

We also asked, “If you are not completely satisfied with UV technology, please list some information on how it could be improved in your opinion?”

Actual reader feedback, “I believe UV is the most misused technology in the market.”

Mike Roberts, sales and technical consultant for UV Superstore, provides a response. “As with just about anything else in this world, some can find a way to misuse [UV],” says Roberts. “UV, [in addition to being used as a disinfection method], is also used for ozone generation, ozone destruction, TOC destruction and chlorine destruction. With each of these applications, UV has varying degrees of effectiveness and must be evaluated on a cost to benefit basis for each individual application to determine if it is the best overall solution for a particular client’s needs.”

And, according to Pieter de Vries, product development manager for UVDynamics Inc., if buyers research the UV market and do proper water chemistry testing, misuse should be a non issue.

“If you know what the flow rate you want is and you know what the UVT (ultraviolet transmission) is, you can choose the correct chamber that will give you the dose you are expecting. A serious UV company will also tell you what the dose is, what the UVT is that they are specifying that dose at and will always tell you the [expected] lamp life,” adds de Vries. “However, the biggest user error is that they don’t do enough testing of the water.”

This water testing can indicate contaminants that can block the UV’s light from effectively working and draw attention to pretreatment needs.

Roberts continues and addresses other common misuse factors. He concurs that the most common error is not taking into account the quality of the incoming water. “UV dosage is sensitive to particulate matter in the water because UV is a contact disinfectant. If particulate matter is affecting the UV intensity, dosage levels may not be high enough to be effective for some pathogens, particularly those that happen to be farthest away from the UV source,” says Roberts.

While Roberts adds that it is possible to treat less than ideal water by increasing the size of the unit, this can result in increased costs for the UV unit. “The most economical method of sizing is to test the water to make sure it meets the manufacturer’s recommendations for water quality, and if it doesn’t, to put into place the proper pretreatment methods,” he explains.

Additionally, with UV units and most other water treatment equipment, you get what you pay for; so if you buy cheap, experts say to be ready for cheap results that can be construed as misuse.

Taste and maintenance issues

One respondent commented that UV technology impacts the taste of water. A rebuttal is offered by de Vries. “If UV is impacting the taste of your water, you may have some other serious issues in your treatment system,” he says, adding that if an end-customer is complaining of UV impacting the taste of their water, dealers should look at the big picture, including power source and supply lines to the unit. An electrical issue, says de Vries, while rare, can induce a metallic taste in the UV treated water.

Maintenance and operation issues were brought up by some respondents. One respondent suggested that the UV lamps should be easier to replace. Others showed concern about the unit’s brief lamp life.

We presented these issues to our manufacturer experts and received some thoughtful solutions.

The most common user error involved with UV water treatment is neglect of first echelon maintenance, resulting in degradation of UV intensity, notes Roberts.

“Lamps need to be replaced at the manufacturer’s recommended intervals because units are designed for the proper dosage with lamp intensity in mind. Additionally, sleeves need to be kept clean and replaced at the proper intervals, once again to ensure proper transmission of UV radiation and subsequent UV intensity,” notes Roberts.

Manufacturers have added additional features to their units to protect against these two most common errors, namely countdown timers for residential units and UV meters for residential and commercial units. The countdown timer is set when a new lamp is installed and will sound an alarm at the recommended replacement time interval, reminding the homeowner it is time to replace the lamp, continues Roberts.

“UV meters are particularly effective for both residential and commercial/industrial units as they monitor UV intensity and will sound an alarm when the UV intensity falls below a prescribed level. Because the UV sensor is monitoring intensity, it will reflect condition of both the lamps and sleeves,” says Roberts.

Certification

One respondent noted, “Lack of third-party certification.” And, de Vries agrees that this area has been a legitimate concern for a while. The majority of units sold to residential and light commercial settings are not certified. While NSF/ANSI Standard 55 does certify Class A and B units, de Vries suggests that market confusion is leading to misuse and missed expectations.

Class A units have been designed to inactivate and/or remove microorganisms, including bacteria and viruses, from water. Class B systems are manufactured for supplemental bactericidal treatment of disinfected public drinking water or water that has been shown to be acceptable for drinking.

“It can become very difficult because the only certified equipment is technically inadequate for the job — the Class B units — or technically too complicated, troublesome and expensive so people look elsewhere [for a new technology],” says de Vries. “Instead, what we are seeing is people placing more value on the manufacturer and its credibility.”

Other respondent issues cited included: Improved power savings; electronic failures; need assurance that the UV is working; and fouling issues.

Dealers that are currently experiencing issues with UV units, such as those discussed in this article, should contact a legitimate UV manufacturer for solutions, literature and specifications. Frequent water testing before and after installation and using the tools provided by UV manufacturers, such as field testing kits for UVT, can help alleviate many of these technical issues.