Working to measure nitrous oxide emissions N2O at Panheel

Pilot into nitrous oxide emissions is no laughing matter

The Waterschapsbedrijf Limburg (WBL)’s wastewater treatment plant (WWTP) at Panheel in the Netherlands treats the wastewater of approximately 38,500 pe using proven Nereda technology. Commissioned in 2021, the plant has more recently been selected for nitrous oxide (N2O) measurement trials to help the water company identify and mitigate against its N2O production, in a bid to reduce Greenhouse Gas (GHG) emissions.

What is nitrous oxide (N2O)?

N2O – otherwise known as laughing gas – is a chemical compound, which at room temperature is a colourless non-flammable gas. At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen. It is also 265 times as potent as carbon for heating the atmosphere and causing climate change, so the need to identify and reduce emissions is high. Nitrous oxide is produced as an intermediate chemical during both nitrification and denitrification in biological waste water treatment.

Combatting climate change

As part of the Klimaatakkoord (Climate agreement), the Dutch water authorities have agreed to reduce their CO2 footprint, in the journey towards net zero carbon. N2O has a significant impact on Greenhouse Gas (GHG) emissions, so N2O emissions must be quantified, and if possible, reduced too. Working in cooperation with WBL and TU Delft, Royal HaskoningDHV is working on a project to measure nitrous oxide production and emission from a full-scale Nereda plant.

Nereda technology and N2O

The project includes measuring the nitrous oxide in the liquid phase and the gas phase of the treatment process. In this way, it will be possible to measure not only what is emitted in the gas phase, but also what is produced – and when – during the liquid phase. This will provide pivotal information on both the production and emission of N2O and provide intelligence into what process change would be required to potentially lead to lower N2O emissions.

The second phase will be to implement such process changes in one reactor at Panheel WWTP while continuing to measure the emissions in the other reactor. Ultimately, this should provide insights into how N2O emissions can be limited in both Nereda plants and other technologies.

The pilot with start in November 2022 and is expected to last 1 year. First results are expected in the summer of 2023.