Discover the Editor's Choice: From each issue of the leading journal Water Science & Technology  the core team of editors select one outstanding paper to make Open Access and share across IWA Publishing platforms. 

IWA Publishing is pleased to announce that the 21st Editor's Choice Paper, selected by Professor Wolfgang Rauch is now Open Access: 

"Quantifying methane emissions from anaerobic digesters"

J. Tauber, V. Parravicini, K. Svardal and J. Krampe         

https://doi.org/10.2166/wst.2019.415

Why was this paper selected as Editor's Choice? 

Anaerobic digesters are usually seen as an environmental friendly method for producing renewable energy in form of biogas. However, recent research advocates that greenhouse gas emission (i.e. methane) from the digester is significant and needs to be considered for climate effect evaluation. Accordingly, the amount of methane emissions from anaerobic digesters has been evaluated in a number of studies with a huge variation in the result, ranging from 0.2% to 7.9% of the total biogas production. This significant uncertainty is due to both the practical complexity of measuring methane emissions in the field and the variations in management and status of real-world digesters. The paper by Tauber et al. addresses this issue with the aim to improve the data quality.     

What impressed me here was the scientifically sound and accurate way this problem has been tackled. The various sources of emissions, such as 1) gas bubbles entrained in the sludge b) gas dissolved in the sludge c) leaks and d) residual gas potential in the sludge have been assessed for 2 digesters at a 260 000 PE plant in Austria. Overall, it has been found that the total emission is here at the lower end of the literature values (i.e. 0.4% of the biogas production).  Even if the research gives numbers only for one specific case study the high scientific quality of the investigation makes this paper a reliable source of information for future evaluations of greenhouse gas emissions from digesters. 

Professor Wolfgang Rauch, Editor-in-Chief.