Demonstration of a Novel Separate Centrate Deammonification Process


  • Sarah Galst, Wendell Khunjar, Robert Sharp, Kathleen O’Connell, Allen Deur, Paul Pitt

Learn more about the pilot project at 26th Ward.

New York City DEP (NYCDEP) WWTPs are facing stringent effluent nitrogen limits. The installation of new processes and upgrades to existing infrastructure is costly, and oftentimes results in energy intensive processes requiring expensive supplemental chemicals. A major component of many BNR designs is the treatment of high-strength sidestream flows generated from solids handing processes.

Sidestream Nitrogen Removal
Conventional sidestream treatment of nitrogen can be accomplished using the conventional approach of nitrification and denitrification, requiring oxygen and usually alkalinity and supplemental carbon addition.

An alternative approach for removing nitrogen in sidestream flows is the use of the deammonification process. The deammonification process requires conversion of ~50% of the influent ammonia into nitrite followed by the simultaneous removal of ammonia and nitrite by anammox bacteria without carbon addition. For deammonification processes to be successful, stable production of nitrite and sufficiently long solids retention times (SRT) for anammox bacteria growth are needed.

There are several existing commercial deammonification processes available which achieve nitrite production using patented approaches for repressing NOB and retaining anammox bacteria, and requiring seed bacteria from elsewhere to startup and maintain the process. Given the existing configuration of NYC WWTPs, conversion to any of these processes will require substantial capital upgrades, modifications to operating practices, and purchase of seed.

Innovative Sidestream Nitrogen Removal – Separate Centrate Deammonification
Work on the development and testing of a novel strategy that exploits existing infrastructure to circumvent these challenges is ongoing in a pilot demonstration funded by NYSERDA, NYCDEP, Hazen and Sawyer, Manhattan College, and Columbia University. In this innovative separate centrate deammonification process (SCAD), ~50% of the influent ammonia in the centrate is converted to nitrite and then nitrate by AOB and NOB. This nitrate is then subjected to denitratation (conversion of nitrate to nitrite) using glycerol-based denitrification, powered by specialist heterotrophic bacteria. This is followed by the simultaneous removal of ammonia and nitrite via anaerobic ammonia oxidation.

In this SCAD option, maximum theoretical savings of 50% in oxygen supply and 80% supplemental carbon can be achieved relative to the existing conventional nitrification/denitrification approach. Further, the SCAD process is novel in that it does not seek to repress NOB activity, but instead uses glycerol to stimulate nitrite production, exploiting the natural predisposition of the bacteria to produce nitrite.

The objectives of the ongoing demonstration are to:

  • Enrich anaerobic ammonia oxidizing bacteria for the deammonification process from the mixed liquor of the SCT process at the pilot facility

  • Test different operational strategies for controlling deammonification using a pilot that mimics full-scale WWTP operation using limited glycerol addition

  • Quantify the potential reduction in costs associated with SCT using deammonification
  • For more information or a copy of the full paper, please contact the author at

    Hear about new publications with our email newsletter

    We will never share your details with anyone else.


    Newsletter Newsletter

    Horizons Fall 2017 (pdf)

    Horizons showcases significant water, wastewater, reuse, and stormwater projects and innovations that help our clients to achieve their goals, and can help you achieve yours. Articles are written by top engineers and process group leaders, demonstrating and explaining the beneficial application of a variety of technologies and tools.

    View previous issues »