$17.50 plus tax (Refund Policy)

Buy Article:


Ultrasound refers to sound energy with frequencies above the audible range; that is, starting at about 20 kHz. Using ultrasound for enhanced sludge digestion relies on inducing cavitation in the liquid to produce lysis of the cellular sludge material, thereby increasing the availability of the organic material to bacteria in anaerobic digesters. This paper presents the results from a fullscale ultrasonic trial at Orange County Sanitation District (OCSD) in 2002.

The benefits of enhanced anaerobic digestion include:

Increased gas production

Greater solids destruction

Improved digester stability

Reduced digester foaming

Improved biosolids dewaterability

The demonstration trial at OCSD ran for 5 months. In order that a direct comparison could be made between sonicated and unsonicated feed sludge, two digesters (test and control) were chosen for study. These were operated under identical conditions, and the proportion of TWAS fed to both digesters was maintained at 60 – 65% throughout. This enabled the results to be compared both against baseline conditions (longitudinal study) and between digesters (crosssectional study) so that conclusions could be drawn for full installation of ultrasound sludge treatment at all of OCSD's facilities.

At OCSD, the ultrasound unit was located on the thickened waste activated sludge (TWAS) feed line to the test digester. Compared to the control digester, significant enhancements of gas production (50% increase) and solids destruction (15 percentage points increase) were achieved by sonicating the secondary sludge. The increases were comparable to the results from a similar UK trial.

Document Type: Research Article

DOI: http://dx.doi.org/10.2175/193864703784606774

Publication date: January 1, 2003

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 These proceedings are not peer reviewed.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access.
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • ingentaconnect is not responsible for the content or availability of external websites



Share Content

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
ingentaconnect 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