ON-MET: measuring methane at Danish wastewater treatment plants

Wastewater treatment plants with biogas production face new requirements to document their methane losses. As the water sector puts more focus on the green transition, plants must prepare self-monitoring programmes and carry out routine leak checks. That calls for a measurement method that is both practical and precise.

The ON-MET project

ON-MET (July 2024 – June 2026) is led by Danish Technological Institute and supported by VUDP-foreningen. Together with four Danish wastewater utilities and Devlabs, the project tests a new method for quantifying the total methane release from a treatment plant.

Methane sensors are placed around the plant and measure continuously. The readings are compared with measurements made using the tracer gas method, where a known amount of gas is released in a controlled way while measurements are taken. The aim is to understand how methane emissions depend on the load on the plant, climatic conditions and operating practice, and to turn that into guidance that helps plants adjust their operation and reduce emissions.

Our part

Devlabs' role was to develop and optimise the methane sensors and the user interface behind them, so the measurement system could be used in practice at the plants. Along the way, we updated our online data platform, the sensor communication and the calibration of the sensors.

What we learned

The project has given us hands-on experience of measuring methane at full-scale treatment plants, where concentrations are low and change quickly — conditions that place high demands on both the sensors and the data behind them.

Thank you to Danish Technological Institute and the participating utilities for a good collaboration.

Read more about ON-MET at Danish Technological Institute