Swedish water treatment plants release far more greenhouse gases than previously estimated. Researchers confirmed this finding using specially equipped drones.
Scientists examined twelve Swedish treatment plants that use sludge digestion to produce biogas. The investigation employed drones with custom sensors measuring methane and nitrous oxide emissions.
Professor David Bastviken from Linköping University led the study. He stated that emissions were approximately 2.5 times higher than UN climate panel IPCC's calculation models indicated.
Bastviken emphasized this represents a completely new measurement approach. "We can measure with high precision across large areas," he explained.
The professor clarified that treatment plants shouldn't be portrayed as environmental villains. He noted they're doing their best to reduce emissions but lacked proper tools and data.
"They're doing tremendous work. This new technology isn't really about detecting emissions, but about fixing them. It's technology to help the sector," Bastviken said.
Methane and nitrous oxide emissions primarily occur after digestion completes. They emerge when residual sludge gets stored in piles before agricultural use as fertilizer.
According to IPCC data, water treatment plants handling household and industrial wastewater account for about 5% of human-caused methane and nitrous oxide emissions.
This revelation highlights how even well-intentioned environmental infrastructure can have hidden climate impacts. The gap between estimated and actual emissions shows the importance of direct measurement methods.
Sweden's treatment plants now have an opportunity to address these previously undetected emission sources using the new drone technology.