Swiss Federal Office of Energy; Axpo Kompogas AG, Glattbrugg, Switzerland; Services Industriels Genève (SIG), Switzerland
October 2009 – December 2011
Yves Membrez, EREP SA, Aclens, Switzerland; Dr. Arthur Wellinger, Nova Energie GmbH, Aadorf, Switzerland; Hélène Fruteau de Laclos, Préverenges, Switzerland.
There are numerous standardized anaerobic digestibility tests to determine the potential amount of biogas production from a certain organic substrate, liquid or solid. These tests are published in international norms but are quite different. The design of biogas installation do however depend on the results of the biogas production tests since they influence the size of the digesters and the number of units needed for biogas transformation. The aim of this project is therefore to evaluate all the different tests available, to identify the most critical issues of the tests and to finally propose a new protocol that allows to determine the biogas production potential of a organic substrate that reflects best maximal biogas production from the specific waste in a full scale installation.
Recent inter-laboratory studies have shown that the results of BMP tests can vary considerably and a comparison of BMP test norm protocols showed that the procedures are not rigorously defined, thus leaving room for interpretation. We developed a test protocol based on the existing ones but defining all steps precisely and to test the influence of the origin of the inoculum and its adaptation to the test substrate. The results showed that the amount of methane produced per gram of substrate volatile solids added varied only slightly with the different inocula used and that adaptation to the substrate did not increase the methane production from complex substrates. The reproducibility of the tests was good and tests with cellulose showed a methane production close to the theoretical methane yield. Future efforts will be directed to the comparison of BMP estimations with biogas production of full-scale installations from the same organic substrates.