Climate Impact of N2O
State of the Science Report
In 2013, the Global Water Research Coalition published a State of the Science Report. One of the central conclusions was that Wastewater Treatment Plants (WWTPs) can emit extensive amounts of N2O under certain process parameters and conditions. Studies in the Netherlands, France, USA, and Australia showed that the N2O emission can account for up to 90% of their total carbon footprint.
If you want to learn more about the climate impact of N2O, you can find the full report at www.globalwaterresearchcoalition.net/reports/, just search for N2O.
Large Variations Not Included in Emission Factor
Traditionally, WWTPs used the IPCC emission factor of 3.2 g N2O/PE/year, because directly monitoring emissions was complicated and costly. However, studies suggest that this emission factor is most likely an underestimation, by up to ten times. Leading scientists suggest that the employment of an emission factor is inadequate, given the large variation of emission. Their recommendation is to implement direct measurements.