Skip to main content

A Little Dab Will Do: Acid Sludge Addition to Promote Phosphorus Release Prior to Anaerobic Digestion

The full text article is not available for purchase.

The publisher only permits individual articles to be downloaded by subscribers.

or click here to sign up for a free trial


The Madison Metropolitan Sewerage District (MMSD) is planning an upgrade to its solids handling processes, which will include acid-phase digestion and phosphorus (struvite) harvesting. Research has been conducted for the past ten years by MMSD and the University of Wisconsin-Madison on methods to promote phosphorus release from waste activated sludge (WAS) to permit removal or recovery of the phosphorus prior to anaerobic digestion. Recent research has demonstrated that the planned acid-phase digester sludge added to WAS in small quantities promotes phosphorus release quickly, consistently, and with little added volume to solids handling processes. Using this method, phosphorus release rates from the WAS average 40% to 45% within approximately 6 hours. Volatile fatty acids (VFAs) contained in the acid sludge were confirmed to be the critical component in promoting the release. The most effective VFA:Total Phosphorus Released ratios were found to be in the range of 2.5:1 to 4:1, which is lower than typical values found in literature.

Keywords: Phosphorus release; VFA; acid phase digestion; acid sludge; anaerobic digestion; phosphorus harvesting; phosphorus recovery; struvite; volatile fatty acids; waste activated sludge

Document Type: Research Article


Publication date: January 1, 2011

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 These proceedings are not peer reviewed.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
  • Ingenta Connect is not responsible for the content or availability of external websites

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
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