Process-related greenhouse gas emissions from municipal wastewater treatment represent an important but still uncertain contribution to utilities’ overall carbon footprint. Reducing this uncertainty is a prerequisite for effective mitigation.

Aquafin, the Flemish wastewater utility, has carried out a series of emission measurement campaigns across the wastewater chain, including septic tanks, wastewater treatment plants, and sludge treatment processes. This poster presents results from these measurements covering mainstream treatment as well as sludge-related processes such as sidestream nitrogen removal (SHARON and Anammox), sludge drying, and mono-incineration. Based on these campaigns, Aquafin has derived utility-specific emission factors and compares them with IPCC Tier 1 default values, illustrating differences and implications for emission inventories.

The poster further highlights mitigation measures that have been suggested or already implemented, directly informed by measurement outcomes. Ongoing work is also presented, including hotspot screening using portable methane analyzers, detailed measurements on aeration tanks at two WWTPs using floating hoods, and the startup of sewer emission studies combining concentration measurements, biofilm analysis, and methane modelling.
Finally, future measurement planning is outlined, with the main objective of improving scope 1 emission estimates through Tier 2 and Tier 3 approaches, supporting more targeted mitigation and robust decision-making.