Request for Proposals: Advancing the Understanding of Nitrous Oxide Emissions

This project aims to accurately quantify annual whole-plant emissions, from several large facilities that employ commonly used treatment processes. The project will provide the information necessary to answer a larger question, “How significant are wastewater facility N2O emissions in the context of country-level GHG inventories?” In addition to N2O monitoring, the project will also investigate process conditions that lead to N2O formation for each facility studied. This study will provide preliminary guidance on how to mitigate N2O emissions, as well as which emissions factor is most appropriate to use for facilities that cannot quantify their N2O emissions through monitoring. The outcome of this project will advance the knowledge about direct N2O emissions from wastewater systems. Project outcomes will be applicable to all utilities with common mainstream treatment processes.

Project Objectives

• Provide accurate whole-plant N2O emissions estimates for several water resource recovery facilities (WRRFs) that employ commonly used treatment processes, by employing continuous online monitoring for a minimum one-year period.
• Develop guidance on process conditions that lead to high N2O formation risk at the facilities, by monitoring other process conditions alongside N2O production.

Funding Information

• The maximum funding available from WRF for this project is $250,000. The applicant must contribute additional resources equivalent to at least 33% of the project award.
• Project Duration: The anticipated period of performance for this project is 24 months from the contract start date.

Research Approach

• Identify facilities for monitoring that meet the following criteria:
  • Ability to monitor whole-plant secondary treatment.
  • Have installed or are willing to install N2O sensors on any unit process off-gas or inline liquid phase sensors, which are used to monitor and control the process continuously.
  • A combined measure of greatest applicability to other WRRF utility subscribers (with considerations of common treatment process and size of facility).
  • Some level of nutrient removal practiced (N2O formation is linked with nitrogen removal processes). The proposer is encouraged to have plants with both with and without nitrogen removal.
• The proposer is encouraged to describe how to approach monitoring across heterogeneous configurations including details on the plant types and configurations, as well as the plan to monitor at each location.
• Based on best practices, design monitoring programs for each facility to include relevant parameters to meet the goals of the project. If possible, include unit process monitoring in addition to the whole-plant monitoring.
• Analyze and report on data collected from the monitored facilities, commenting on which process conditions led to higher or lower N2O formation and the potential mechanisms/pathways responsible.
• Develop a set of process N2O emission factors and a simple decision tool to help utilities decide which factor is most appropriate at their facilities.
• Develop an estimate (with uncertainty range) of what total process N2O emissions might be in the United States, Canada, Australia and other countries where possible. Using the emission factors derived in this project, compare estimated N2O emissions at the facilities identified with emission factors in U.S. EPA National Inventory.
• Develop a standard method for conducting on-site N2O monitoring.

Expected Deliverables

• Literature review synthesis built from completed and ongoing research
• A final report including estimates of N2O emissions from monitored facilities, analyses of all data collected, insight on N2O formation risk factors, a simple decision tool, and recommendations for future research
• One open-access peer-reviewed paper
• Webinars and other outreach efforts

Eligibility Criteria

• Proposals will be accepted from both U.S.-based and non-U.S.-based entities, including educational institutions, research organizations, governmental agencies, and consultants or other for-profit entities.

For more information, visit Water Research Foundation.