Compiled by Isabel “Izzy” Medeiros and James P. Malley, Jr., Ph.D., University of New Hampshire
Owners and operators of UV technology are an important stakeholder group; these professionals have limited time and often prefer to remain anonymous when providing feedback. As a result, UV Solutions now builds this column from responses to a Qualtrics survey sent out each quarter with the help of UNH graduate students. For this “One Water” themed issue, the survey was sent out to focused email lists obtained from 2024 AWWA ACE attendees.
The desire in this month’s Operator’s Corner was to capture input from facilities that are applying UV technologies for applications in wastewater, drinking water and all other “one water” -related applications. The latter are using UV-based advanced oxidation processes (AOPs) to treat contaminants of emerging concern either in water reuse or in water contamination and remediation projects. The largest response pool of 16 respondents were using UV systems for wastewater disinfection, 10 responses came from UV systems that are applying UV in drinking water disinfection (mainly to achieve Giardia and Cryptosporidium disinfection credit) and the remaining five respondents had installed UV-H2O2 systems to provide drinking water from wastewater or highly contaminated source waters (water reuse).
Comment on the advantages of using the UV system.
Most respondents (22) mentioned the elimination of disinfectant chemicals or disinfectant quenching agents as a significant improvement and advantage since switching to UV technologies. Thirteen respondents indicated that the UV system meshed better and was easier to monitor, control and record-keep than the Supervisory Control and Data Acquisition (SCADA) systems at the facility. Four facilities indicated that their discharge permit compliance improved with their switch to UV technology vs. chlor/dechlor.
Comment on the disadvantages of using the UV system.
It was interesting to read from 15 respondents that their UV systems require more power use and more labor time than initially expected. Twenty respondents registered complaints about lamp fouling and cleaning needs. Six respondents indicated frustrations with obtaining needed replacement items, specifically noting lamps, sleeves, sensors and ballasts that were “of good quality and arrived in a timely fashion.” Two respondents specifically called out the current state of their UV-H2O2 systems as being difficult to optimize in terms of efficient chemical and power use. Five respondents noted that there has been a marked decrease in the quality of customer service provided by their UV equipment suppliers in the past two to five years.
Comment on experiences, concerns or operations observations about the installed mercury-based UV lamp systems.
Eight respondents indicated their major concern was future availability, forcing them to have to change systems if mercury use is banned. Five respondents indicated that this concern never came up or impacted their operations. Two respondents indicated there was a negative public response to adopting UV systems because of mercury content and potential mercury release. Seven respondents indicated they see no other options but encourage research to develop better, more sustainable alternatives.
Provide experiences, thoughts or questions about the application of UV LED-based systems to meet the specific needs of the respondent’s facility.
All the drinking water system respondents indicated they were aware of emerging research. Of these, eight remarked that it would be attractive to have mercury-free lamp alternatives. Five respondents remarked that they have not seen any fully EPA-validated models in the marketplace. One user asked if these systems have the same UV sensors and cleaning devices as the conventional UV systems. Three respondents mentioned their consultant had done due diligence in looking at this technology and concluded the systems do not have any demonstrated track record in municipal water nor enough manufacturers that can competitively bid their projects at this time (they do not want to deal with sole-source situations). Half of the wastewater systems respondents said they are looking forward to the day when they may have standard options to consider due to the elimination of mercury-containing lamps. Five indicated that it would be attractive if the lamp life and energy-savings claims were demonstrated in large operating plants. Four facilities asked how UV LED lamps are cleaned and whether there was long-term success in treating conventional wastewater effluent. Two respondents indicated they were not aware of any options available for using UV LEDs in UV-H2O2 systems like theirs.
Share any additional thoughts, observations or experiences relative to the respondent’s UV system.
Five facilities treating wastewater and three drinking water facilities indicated they have difficulty with meeting UV system performance requirements due to decreasing and often variable UV transmittance (%UVT). One suggested that UV designs need to be based on more conservative (lower) %UVT values.
All five of the UV-H2O2 systems that responded indicated that relying upon H2O2 was problematic and hoped for alternatives due to difficulties with supply chains, costs and the need to remove H2O2 residuals.
Six UV system respondents indicated they are evaluating alternatives to their current UV systems since the systems are older and operate inefficiently, especially with respect to the electronic components. Two of these users indicated they hope to find designs that “require less equipment, especially lamp.”
Suggested Reading
The authors note that Randall and Kwan published an article, “The UV Industry Survey: Insights from Water Professionals,” in Journal AWWA Volume 117, Issue 3, p. 48-58, which interested readers should check out.
This column provides unique insights via survey results derived from questionnaires given to users of UV technologies in a variety of application settings.
