Skip to main content


Buy Article:

$17.50 plus tax (Refund Policy)

Or sign up for a free trial


Step feed biological nitrogen removal (BNR) is an effective process that can be readily adopted in existing activated sludge plants to achieve significant nitrogen removal. The process has been demonstrated in bench scale, pilot plants and full scale treatment facilities. Step-feed BNR incorporates alternating oxic and anoxic zones. The anoxic zones coinside with the feed locations of primary settling tank effluent. As the flow of wastewater being treated travels through the tank, nitrification takes place in the oxic zones and denitrification in the anoxic zones. In a full scale demonstration facility at the Wards Island WPCP in New York, the process achieved 50% nitrogen removal at an average operating temperature of 15°C, a SRT of 13.6 days, and without adding external sources of alkalinity or organic carbon. The average specific nitrification and denitrification rates measured were 0.081 and 0.026 mg NOX-N per mg MLVSS per day, respectively. An important challenge that must be overcome for a successful operation of the process is adequate control, removal, and disposal of froth which typically develops in BNR treatment plants.

Document Type: Research Article


Publication date: January 1, 2001

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 These proceedings are not peer reviewed.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

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