Ten years after the first study on nitrous oxide emissions from Dutch wastewater treatment works, a Community of Practice (CoP) Nitrous Oxide was established in 2019. The CoP has significantly contributed to accelerating nitrous oxide research in the Netherlands. The Dutch Water Authorities have the ambition to be Climate Neutral in 2030.

With the start of the Nitrous Oxide Acceleration Program in 2024, the research into nitrousoxide emissions has gained even more momentum. By the end of 2025, it is expected that continuous nitrous oxide measurements will be conducted at approximately 60 treatment works in the Netherlands, and this will continue until the end of 2027. This will in the future and already now provide a wealth of information. The lessons on setting up a good monitoring campaign for measuring nitrous oxide emissions to achieve a reliable and uniform emission factor are shared in this report. 

We do this from a Dutch perspective, but the lessons learned are valuable for everyone. With the experience from the Netherlands, the lessons learned can be directly applied and contribute to accelerating nitrous oxide research that is now being set up and started worldwide.

The objectives of the acceleration program in the Netherlands are:

• Determine the actual nitrous oxide emissions per WwTW as accurately as possible, to ultimately establish emission factors for the Netherlands that are internationally recognized
• Determine a validated set of mitigation measures, that provide insight into the effect of mitigation measures on the nitrous oxide emissions

To achieve these goals, a lot of work has been done in the Netherlands over the past two

years to establish a monitoring protocol that ensures a uniform method of measuring and calculating emission factors. The experiences and knowledge described in this handbookcome from all 21 Water Authorities participating in the acceleration program in the

Netherlands. In this handbook, we address:

• Determining the correct nitrogen load treated in the treatment work, which is essential for calculating an emission factor.
• Determining the number of sensors to be placed and where to place them, and how to perform a location determination. The next step is the purchase and installation of the sensors.
• Calibrating and replacing the sensor head at the right time is essential to achieve a reliable and as complete as possible dataset! To achieve this, it is also crucial to detect deviations in time and take the appropriate actions immediately.
• Calculating nitrous oxide emissions and presenting the data that needs to be available for this.
• Presentation of which process parameters are valuable to measure and collect to gain maximum knowledge about the level of emissions and how to reduce them.