Description
Nitrous oxide (N2O) is the largest source of direct greenhouse gas emissions at many wastewater treatment plants. Yet the water sector has never had a standardised approach for measuring these emissions. As a result, data are often inconsistent and difficult to compare, limiting benchmarking, knowledge sharing, sector-wide reporting and progress towards effective emissions reduction. This protocol is the first globally coordinated protocol for monitoring and quantifying N2O at full-scale wastewater treatment plants in real time. Whether you are planning your first monitoring campaign, designing a measurement program across various plants, or calculating emission factors for reporting, it will help you choose a method, set up the equipment and turn your measurements into valuable insights and numbers you can stand behind. It covers the two approaches feasible at full scale, gas-phase and liquid-phase, and provides practical guidance for sensor and equipment selection, installation, data processing and emission calculation. It sets out how to choose representative monitoring locations, including tailored approaches for covered systems and surface-aerated configurations, and describes how to plan sampling campaigns, calculate emission factors and collect supporting operational data. A structured decision-making tool helps utilities set up N2O quantification at an organisational level and choose a monitoring strategy to suit plant conditions and objectives. It draws on 30 case studies from 10 countries, contributed by 20 utilities, and the expertise of 42 practitioners and 19 academics. This first edition reflects current best practice and represents the beginning of an evolving framework that will be refined as new knowledge and practical experience become available. Its goal is to provide water utilities with a consistent approach to monitor and quantify N2O emissions, enabling the development of a globally comparable dataset and supporting the establishment of an internationally accepted standard for wastewater emissions measurement.