Skip to main content

Reducing Ammonia and Phosphorus Recycle Loads by Struvite Harvesting

Buy Article:

$9.50 plus tax (Refund Policy)

Or sign up for a free trial

The Clean Water Service's Durham AWWTP has a 0.10 mg/l total P discharge limit, which is achieved through a combination of Enhanced Biological Phosphorus Removal (EBPR) and tertiary chemical polishing. EBPR Sludge is digested anaerobicly resulting in a dewatering centrate that is rich in phosphorus and ammonia. Typical values for the centrate are 600 mg/l soluble PO4-P and 1,200 mg/l NH3-N, resulting in 25% and 30% of the phosphorus and ammonia load to the plant, respectively. Centrate storage is used to shave the diurnal peak loads and fill the diurnal low points. Clean Water Services (CWS) did not want to add metal salts to the centrate to capture the phosphorus since it would defeat the point of removing phosphorus biologically with EBPR and result in increased operating costs for chemical consumption and sludge disposal. Metal salt addition would also not reduce the ammonia recycle.

Clean Water Services was looking at side stream treatment options that could reduce the nutrient recycle load to the plant. The Ostara struvite recovery process, which adds magnesium to the phosphorus and ammonia rich centrate to create struvite, (magnesium ammonium phosphate hexahydrate, commonly called struvite or MAP) was piloted over an 8 week period from April to June 2007. This could reduce both phosphorus and ammonia that is returned to the plant for treatment and makes a product that has beneficial use as a slow release fertilizer. The pilot was very successful, demonstrating process stability despite multiple power interruptions from switchgear maintenance and re-started without difficulty. Ortho-phosphate was reduced from an average of 505 mg P/l to25 mg P/l for a 95% average reduction in the recycle stream. Ammonia was reduced from an average of 1,200 mg N/l to 980 mg N/l for a19% average reduction. That translates to a plant influent ammonia reduction of 6% and an influent phosphorus reduction of 24%, which is greater than the 22% reduction resulting from the statewide phosphate detergent ban. The pilot was operated at four different hydraulic loading conditions to determine the optimal reactor throughput for a full-scale facility. Installation of a full scale facility based on the results of this demonstration is currently planned for construction in fourth quarter of 2008.
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: 2008-01-01

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