Uncorrected Proof Towards a standardization of biomethane potential tests

Production of biogas fromdifferent organicmaterials is amost interesting source of renewable energy. The biomethane potential (BMP) of these materials has to be determined to get insight in design parameters for anaerobic digesters. Although several norms and guidelines for BMP tests exist, interlaboratory tests regularly still show high variability of BMPs for the same substrate. A workshop was held in June 2015, in Leysin, Switzerland,with over 40 attendees from30 laboratories around theworld, to agree on common solutions to the conundrum of inconsistent BMP test results. This paper presents the consensus of the intense roundtable discussions and cross-comparison of methodologies used in respective laboratories. Compulsory elements for the validation of BMP results were defined. They include the minimal number of replicates, the request to carry out blank and positive control assays, a criterion for the test duration, details on BMP calculation, and last but not least criteria for rejection of the BMP tests. Finally, recommendations on items that strongly influence the outcome of BMP tests such as inoculum characteristics, substrate preparation, test setup, and data analysis are presented to increase the probability of obtaining validated and reproducible results. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY-NC-ND 4.0), which permits copying and redistribution for non-commercial purposes with no derivatives, provided the original work is properly cited (http://creativecommons.org/ licenses/by-nc-nd/4.0/) doi: 10.2166/wst.2016.336 Christof Holliger (corresponding author) Gabrielle Hack ENAC IIE Laboratory for Environmental Biotechnology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland E-mail: christof.holliger@epfl.ch Madalena Alves João Vítor Oliveira Centre of Biological Engineering, University of Minho, Braga, Portugal Diana Andrade Florian Ebertseder Mathias Hartel Bavarian State Research Center for Agriculture, Freising, Germany Irini Angelidaki Ioannis Fotidis Technical University of Denmark, Lyngby, Denmark Sergi Astals Advanced Water Management Center, The University of Queensland, Brisbane, Australia