Influence of sampling strategies on the estimated nitrous oxide emission from wastewater treatment plants

• Strategies for sampling N2O emission from wastewater treatment were evaluated.
• Long-term sampling is necessary for an accurate estimate of the N2O emission.
• Online sampling is needed to identify the diurnal variability of the N2O emission.

In the last few years, the emission of nitrous oxide from wastewater treatment plants has become a topic of increased interest, given its considerable impact on the overall climate footprint of wastewater treatment plants. Various sampling strategies to estimate nitrous oxide emission from wastewater treatment plants have been applied in different studies. The present study addresses the influence of sampling strategies on the estimated emission by analysing the variability of an extensive dataset of nitrous oxide emissions resulting from a long-term online monitoring campaign at a full-scale municipal wastewater treatment plant. It is shown that short-term sampling is inadequate to accurately estimate the average nitrous oxide emissions from a particular wastewater treatment plant, while online monitoring is indispensable to capture the short-term variability (diurnal dynamics).