Skip to main content

High Load Field Test of a Secondary Clarifier

Buy Article:

$9.50 plus tax (Refund Policy)

Or sign up for a free trial

Secondary clarifiers were field tested for hydraulic characteristics and performance and checked with the Clarifier Research Technical Committee's draft protocol at a Wisconsin, Ohio and North Carolina WWTP. The test clarifiers were two (2) 42.68m (140 ft.) diameter; 35.1m (115 ft.) and 48.78m (160 ft.) x peripheral-feed, inlet, peripheral-overflow clarifiers. Settled solids are collected by a rotating hydraulic header for all four (4) units.

The WWTPs wanted to determine the capacity of the existing secondary clarifier system for use in planning of plant upgrades and permitting. Also, to determine if any upgrades or changes should be considered for the units.

Multiple tests were conducted at average and max flow conditions approximating 800 to 1,700 GPD/sq. ft. (1.36 and 2.9 m/h). Influent mixed liquor concentrations RAS concentrations, effluent TSS, sludge blanket profiles, and flow rates were recorded to document the performance of the clarifier. Sludge volume index (SSVI) and SVI and in-situ dispersed solids (IDS) tests were conducted to quantify the settling and flocculation characteristics of the influent mixed liquor. Hydraulic characteristics of the clarifier were assessed by conducting slug dye and flow pattern/solids distribution and drogue tests.

To run the tests, it was necessary to take basins off-line. It was possible to maintain an overflow rate of up to 1,700 GPD/sq. ft. (2.9 m/h) with a solids loading of up to 50 lbs./sq. ft./day (243 kgs/sq. m/day).

Results of the high load test show a hydraulic and solids loading efficiency well above conventional design parameters. Solids studies showed effluent suspended solids (ESS) levels could be maintained below 20 ppm at hydraulic loading up to 1,700 GPD/sq. ft/day (2.9 m/h) and 50 lbs/sf/d.

The flow pattern was away from the effluent weirs.

The sludge blanket is controlled.

The three (3) studies reported in this paper verify the original work done by Crosby in the late 1970's “that the PF/PO clarifier acts as an upflow clarifier and needs little or no modifications to its design.”

It was possible to maintain, over an eight (8) hour and a 7 day period, an overflow rate of up to 1,700 gpd/sq ft. with a solids loading of up to 50 lbs./sq. ft/day.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article 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