Meeting More Stringent Nitrogen Limits: NYC’s Applied Research Program

Client: New York City Department of Environmental Protection
Location: New York, NY

The NYC Department of Environmental Protection’s Applied Research Program now focuses on developing a body of knowledge to support sustainable Biological Nutrient Removal operations at its Wastewater Treatment Plants that discharge to the East River and Jamaica Bay. With compliance deliverables on the horizon, the DEP must develop design guidelines, fine-tune and implement the selected strategy for reducing nitrogen discharges, and share its findings with other agencies. In joint venture, Hazen and Sawyer is leading the effort to shift this effort from pure research to developing, prioritizing, and implementing practical technologies that will enable the City to meet the upcoming more stringent nitrogen discharge limitations.

Project Outcomes and Benefits

  • Appropriate technologies will be evaluated and selected through pilot and demonstration-level research and development.
  • A protocol will be developed to evaluate new technologies that evaluates whether they should be tested, and establishes a practical research program to obtain useful data as to their effectiveness and feasibility.
  • Successful technology transfer to DEP through hands-on experience at the pilot and demonstration facilities, supplemented by workshops led by industry experts.

The Applied Research Facility at the 26th Ward WWTP has provided DEP with over a decade of pilot-scale research into the kinetics of the nitrification and denitrification reactions that are the backbone of the City's Biological Nutrient Removal program. Lessons learned from pilot-scale research have been incorporated into DEP’s $1.2 Billion Phase I BNR construction program.

PO-88 provides modeling support to refine and optimize BNR operations. This Computational Fluid Dynamic (CFD) model of final settling tank predicts flow patterns of complete infrastructure at varying input conditions. Models help DEP assess a variety of potential designs quickly and cost efficiently before construction is complete.

PO-88 evaluates potential future permit requirements and potential emerging technologies that could meet future effluent limits. Integrated Fixed-Film Activated Sludge (IFAS) has shown promise for other utilities that are required to meet extremely low levels of Nitrogen discharge.

A key challenge to BNR operations is preventing and managing the generation of filamentous froth. Froth control hoods are one of several lines of defense being constructed under Phase I of the program. PO-88 is evaluating how to optimize the operation of these hoods and whether additional lines of defense should be constructed based on demonstration-scale research.

The original mission of the DEP’s Applied Research Program was to determine the most appropriate technology to remove nitrogen from selected New York City WWTPs to meet future stringent nitrogen limits. This was accomplished via the dissemination of the Nitrogen Control Feasibility Plan in 1998, which identified Biological Nutrient Removal (BNR) as the backbone process technology for the City’s Nitrogen Program. In the ensuing nine years, the Applied Research Program contributed to refining the current round of capital construction upgrades and conducting preliminary research into supplemental carbon strategies necessary to meet Consent Order commitments for 2016 and beyond.

The Applied Research Program continues to evolve; pilot facilities that were previously used for basic research will now become applied research and demonstration-level testing facilities, focused on providing the DEP with the necessary tools to effectively implement BNR and operate the highly-dynamic treatment plants.

Achieving sustainable BNR operations involves:

  • Simplifying operations through appropriate technology and training.
  • Designing flexible, adaptable facilities to account for shifts in carbon availability, rising energy costs and other challenges.
  • Establishing a framework for strengthening institutions within the Bureau of Wastewater Treatment, to facilitate continuous learning and research and development, including testing and evaluation of new, innovative technologies.

Leading the development of design guidelines, operations optimization, piloting of new technologies, and technology transfer, Hazen and Sawyer will enable the DEP to achieve sustainable BNR operations and full regulatory compliance within the expected deadlines.

For more information on this project, or to discuss a similar project in your area, contact

Paul Pitt, Ph.D., P.E. at ppitt@hazenandsawyer