Compiled by James P. Malley, Jr., Ph.D., University of New Hampshire, Editor-in-Chief of IUVA’s UV Solutions

Planning for this edition of the Operator’s Corner anticipated the coincidence of the UV Solutions publication with the upcoming AWWA ACE 26 in Washington, D.C. As a result, the 10% of US drinking water utilities estimated by AWWA to be using UV technology were the focus of direct calls and the Qualtrics survey emails. The response included 15 drinking water facilities, which provided the following practical insights for our readers.

What do you like most about the UV technology at your treatment plant?

• Nine responses: It does not involve chemicals.
• Four responses: It requires little maintenance.
• Six responses: It takes up little space.
• One response was “Nothing.”

What do you like least about the UV technology at your treatment plant?

• Seven responses: Sensor checks are very time-consuming.
• Five operators: Constant problems with online UVT monitors.
• One-third of the responses (five): Lamp cleaning is much more frequent than they had anticipated when sold to them.
• Three responses: The units are large and difficult to work on due to the many required walkways.
• Two operators: They never really think about them because they have not caused any problems compared to other hardware they work on all the time.

Describe any tricks of the trade you have developed for operating and maintaining your UV system.

• The frequency of sensor checks was reduced a lot by using control charts created directly by SCADA software to determine if a given duty sensor needed to be checked against a reference sensor with the approval of the state.
• Quarterly lubrication of commonly used connections on UV units made removal for system checks, lamp replacement and electrical repairs much faster.
• During low flow seasons, we changed how we flow pace by taking entire UV trains on and offline rather than individual lamps in a unit. We saw much more uniform lamp aging and replacement this way.
• Our SOP when replacing lamps is to use lamp guards that are like what we use to handle our office’s fluorescent bulbs.
• We have a lot of lamps, so we invested in OSHA-approved lamp-eater equipment to minimize handling, storage and recycling problems.
• Pretreatment for iron and manganese due to red water complaints also made our UV unit operation and maintenance much easier.
• System wipers do not clean our dry sensor windows effectively, so we came up with a schedule for routinely taking the unit offline, draining it and then manually wiping with pole brushes and NSF-approved cleaning products.

If your treatment plant uses a UV advanced oxidation system, what do you like most about it? [Three responses received.]

• It has taken care of our frequent taste and odor complaints.
• We have UV disinfection at one plant and UV with hydrogen peroxide at the other. At the UV disinfection-only facility, we have hassles with UV sensors, but at the UV hydrogen peroxide facility, we do not rely on sensors.
• We think the water tastes better now that we have it.

If your treatment plant uses a UV advanced oxidation system, what do you like least about it? [Three responses received.]

• All three indicated that the storage, handling and feeding of hydrogen peroxide have constant problems.
• Two facilities indicated that they routinely check the strength of their hydrogen peroxide, and it is “all over the place” and degrades rapidly, especially during high-flow demand (summer) season.
• One response indicated that there are numerous electrical issues, from costly bills for power use to problems with the many electrical conduits and connections.
• One response indicated that the hydrogen peroxide system causes annual regulator inspection and paperwork headaches for the facility’s 20,000-pound bulk storage.

Share any other questions or comments related to UV technology at your treatment plant.

• Five mentioned they have heard that UV lamp systems soon will be replaced with newer LEDs and asked if this is true and when that would happen.
• All three of the reuse responses asked if there are affordable alternatives to feeding hydrogen peroxide into their UV systems, with one stating: “like feeding some other less obnoxious chemical like alum.”
• One question received was, “We feed caustic or sodium hydroxide already. Could we use that instead of hydrogen peroxide?”
• Two asked if the plans to install GAC for PFAS at their plants would mean they could stop using the UV hydrogen peroxide system.
• Six responses mentioned that they are not familiar with UV Solutions or IUVA and wondered how they are related to operator memberships from state WWAs.