The wastewater treatment processes can emit large quantities of nitrous oxide (N₂O). In August 2025, an RTO (regenerative thermal oxidizer) plant was commissioned in Switzerland to clean the nitrous oxide-laden exhaust air from the biological treatment stage and the digester treatment. This process removes more than 95% of the N₂O emissions. The plant thus makes a significant contribution to reducing climate-relevant emissions, bringing the net-zero target within reach. 
This new plant is the first RTO plant built exclusively for air directly from the biological treatment stage of a wastewater treatment plant. 

The experience gained in Switzerland is of great value to other plant operators – especially in the context of CO2 neutrality and the search for practical solutions to reduce nitrous oxide emissions.

To further lower the threshold for nitrous oxide reduction, CTP has developed a small, compact system that is integrated into a 20-foot container and can be delivered practically ready for operation. This facilitates the quick and straightforward implementation of similar projects in the future.