Skip to main content

Implementing a Multi-Barrier Approach using Ultrafiltration and UV Disinfection

Buy Article:

$9.50 plus tax (Refund Policy)

Or sign up for a free trial

The Eastern Municipal Water District (EMWD) is expanding the existing Perris Water Filtration Plant (Perris WFP) located in Perris, CA from 10-million gallons per day (mgd) to 20-mgd in order to meet the drinking water needs of its customers. The disinfection philosophy for the expanded facility will utilize the synergy of membrane ultrafiltration (UF), ultraviolet (UV) light, and chlorine disinfection to comply with treatment requirements, while minimizing disinfection byproducts (DBP) formation.

The existing Perris WFP treats Colorado River Water (CRW) by UF followed by chlorine disinfection. California Department of Health Services (CDHS) awards 4-log removal of Giardia and Cryptosporidium and 2-log virus removal for the UF process used at Perris, but also requires post-UF disinfection to provide for 2-log virus inactivation and an additional 0.5-log Giardia to comply with their multiple barrier pathogen control philosophy. The area available at Perris WFP is severely limited at 4.5 acres and would prohibit construction of new chlorine contact basins to provide 0.5-log Giardia inactivation for the ultimate 50-mgd capacity of the facility. For this reason, EMWD chose to move forward with UV disinfection after a thorough evaluation and site visits to existing UV installations.

The two main considerations for assessing water quality for UV disinfection are UV transmittance (UVT) and fouling potential. UVT, a measure of the clarity of the water, varies with source water. The Perris WFP will have the flexibility to treat raw CRW, which consistently exhibits UVT values above 90%, raw State Project Water (SPW) which exhibits considerable seasonal variation (75%–90%), or a blend of the two. As the UVT decreases, the necessary number of lamps increases, the necessary UV intensity increases, and the required exposure times lengthen to provide the required UV dose for inactivation. During the design phase, bench scale testing was performed on the two source waters in order to find the optimum coagulant dose and flocculation time to achieve the target UVT level after UF. EMWD will save operating costs by either blending the two source waters or pre-treating only the raw SPW with coagulation to achieve a consistently high UVT.

In addition to the new UV disinfection and pretreatment facilities, the existing chlorine contact basins will be converted into membrane tanks, and a new finished water pump station and clearwell will be constructed as part of the expansion. The new clearwell is designed to provide for a minimum 2-log virus inactivation using free chlorine, which is the most cost effective method to meet this aspect of the CDHS disinfection requirement.

The existing Perris WFP capacity is critical to EMWD's system in the summer months; therefore full operations must be maintained during the construction period. A staged construction schedule and start-up will be used to minimize downtime.

This paper presents the benefits of the multi-barrier approach adopted by EMWD for the Perris WFP, the process of selecting and sizing the UV reactors, including upstream treatment to optimize UV system design, and the proactive coordination with CDHS to gain approval of this approach.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Data/Media
No Metrics

Document Type: Research Article

Publication date: 2005-01-01

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
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