UV Case Study
James Malley, UNH
Adenovirus requires a very high UV dose of 186 mJ/cm2 (normalized to 254nm wavelength) to achieve a 4-log inactivation credit (USEPA, 2006; 71 FR 654, 2006) when compared to viruses such as polio, hepatitis, and rotavirus which were the basis of prior rulemaking (Yates, et al. 2006). This high UV dose requirement has led to technical challenges and as a result the subsequent Groundwater Rule (GWR) did not specify UV disinfection as one of the best available technologies. Therefore, many small systems using surface waters, GWUDI or ground waters, which could achieve significant microbial risk reduction from the implementation of UV disinfection, have avoided its use. In addition, UV disinfection also reduces the chemical risks from DBPs and lead and copper corrosion by avoiding the need for a strong chemical oxidizer/disinfectant such as chlorine. However, innovative polychromatic UV technologies that emit wavelengths other than 254nm have been shown to inactivate adenovirus in a more sustainable manner and the current USEPA sponsored Cadmus Project No. EP-C-11-039 is working with a team of researchers including Linden and Malley and developing and refining methods to use these polychromatic systems. Project 1 Activity 6 will incorporate the results of this prior research and expand it to full scale.
A group of small system stakeholders has been assembled including state regulatory personnel from the NH Department of Environmental Services, managers of three drinking water utilities ranging from small (3000 people) to very small (83 people), a town engineer, a consulting engineer specializing in small system work, innovative UV technology manufacturers, three small system drinking water operators and town’s people who represent their water boards. These systems are all united by the common need to comply with the GWR and they have challenging circumstances of microbial (a history of boil water notices) and chemical risks (locational increases in DBPs) from their compromised groundwater supplies. These small systems have an array of the managerial, financial and technical challenges previously discussed.
These systems will provide the initial field testing cases for Project 1 Activities. Stakeholder feedback will be critical to the refinement of Project 1 outputs resulting in improved methodologies and enhanced outcomes for the innovative small drinking water technologies applied in Center Projects 2, 3 and 4.
Activity 6 will involve the selection, design and installation of a MP UV system on the selected groundwater site. The system will be carefully monitored for a period of one year of continuous operation. Monitoring will include innovative low wavelength UV sensor readings continuously and monthly monitoring of human enteric viruses before and after treatment, fecal coliforms, heterotrophic plate count bacteria and regulated DBPs. Operational monitoring will also include water flow, energy use, and operation and maintenance requirements and their costs. All analytical and monitoring techniques used will conform to USEPA approved standard methods or other applicable standard methods such as ASTM. Standard operating protocols, quality assurance and quality control procedures will be specified in an approved USEPA QAPP.
Aquionics, Inc. who are members of the USEPA sponsored drinking water cluster referred to as Confluence will provide in-kind equipment support for Activity 6. Interactions with Confluence and their board members will enhance the overall technical quality and widespread applicability of the field testing results. The site chosen for Project 1 Activity 6 will serve as the first full-scale demonstration of an innovative low wavelength UV sensor to allow field control and verification of the adenovirus inactivation. In addition, the innovative LED UV activity in Center Project 2 will be tested at this site allowing stakeholder feedback and side by side comparisons with the MP UV technology.