Skip to main content

An Overview of California's Experience with Ultraviolet Disinfection in Water Recycling Applications

Buy Article:

$17.50 plus tax (Refund Policy)

Or sign up for a free trial

Abstract:

Since the National Water Research Institute's (NWRI) UV Disinfection Guidelines were published in the 1993 for low-pressure, low-intensity horizontal lamp UV systems, the UV industry has developed a number of “nonconforming” systems. Under the NWRI guidelines these nonconforming systems must be tested and their performance verified before they can be used to disinfect municipal wastewater for reuse or recycling applications. Several studies to verify the performance of these nonconforming systems have been conducted at wastewater facilities located in California. Observations from early testing of the nonconforming systems showed that performance similar to UV systems accepted under the NWRI guidelines could be achieved. However, a review of historical data suggests that a great deal of variability in performance (as measured by pathogen inactivation) exists between static testing (collimated beam) and continuous flow pilots.

Based on collimated beam test data, some of the variability may be attributed to the differences in the protocols used to propagate and harvest the pathogen seed used in the testing. Even though the pathogen seed used in these studies was an MS2 bacteriophage, traceable to an ATCC stock culture, there were subtle differences in growing, harvesting, and concentrating the seed stock between the studies.

The lack of standardized protocols for seed handling and collimated beam test conditions may not be the only source of variability in UV system testing. UV system performance at various California reclamation facilities has indicated variable disinfection abilities with variable flow rates, indicating sub par system hydraulics at low flow rates. UV studies are underway to evaluate system hydraulics and disinfection capabilities over variable flow rates.

Without adequate controls in place to aid in the interpretation of results, the observed variations between collimated beam and continuous-flow pilots may be leading to inappropriate conclusions regarding the performance of these units. Because subtle variations can be magnified in full-scale facilities (resulting in under or inadequately designed facilities), the need for developing a standard testing protocol has become obvious.

This paper will discuss the problems and pitfalls of the current verification process using examples to illustrate how these observations and hypotheses are being used to lead toward standardization of some aspects of the testing protocol. Properly developed, a standardized testing protocol will produce results that better reflect the performance of the UV systems. In turn, this will ensure more consistent performance of UV systems through proper design and construction.

Document Type: Research Article

DOI: https://doi.org/10.2175/193864700784546576

Publication date: 2000-01-01

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more