Ultraviolet radiation (UV) effectively inactivates common pathogens found in ground and surface waters such as Cryptosporidium, Giardia, and most bacterial pathogens (e. g., E. coli). Water treatment facilities recently started using ultraviolet radiation for disinfection of drinking water, replacing standard chemical treatment. Typically, low-pressure and medium-pressure mercury lamps (LPM and MPM, respectively) are used in the UV reactors at the facilities. In these reactors, water flowing at a given rate should receive an appropriate UV dose. UV sensors mounted on the wall of the UV reactor or inserted into the water flow monitor the dose level by measuring the irradiance from the lamps. The UV sensors currently in use have a variety of designs and performance characteristics. Austria and Germany have developed or are developing standards for the sensor design and performance. These two standards differ in their requirements and do not address many of the problems associated with the UV monitors. Furthermore, there are already many water plants employing UV sensor systems consistent with one or the other standard. To resolve this confusion, American Water Works Association Research Foundation (AwwaRF) decided to develop new guidelines for UV monitors. The National Institute of Standards and Technology, USA (NIST) is participating in this project in collaboration with Carollo Engineers (Boise, ID), CDM (Denver, CO), and the University of Veterinary Medicine (Vienna, Austria). NIST studied the current UV water disinfection standards, NORM M5873-1 and M5873-2  (Austria), and DVGW W294 3  (Germany), on the requirements for UV sensors for LPM and MPM lamp systems. Pertinent to the study, NIST is measuring and analyzing the characteristics of various types of UV sensors. This information will aid in the development of new guidelines which will address issues such as sensor requirements, calibration methods, uncertainty, and traceability.
Pub Type: Journals
calibration, disinfection, irradiance, measurement, responsivity, standard, ultraviolet, UV, water