Description:
<jats:title>Summary</jats:title><jats:p>Obtaining a reliable estimation of the methane potential of organic waste streams in anaerobic digestion, for which a biochemical methane potential (<jats:styled-content style="fixed-case">BMP</jats:styled-content>) test is often used, is of high importance. Standardization of this <jats:styled-content style="fixed-case">BMP</jats:styled-content> test is required to ensure inter‐laboratory repeatability and accuracy of the <jats:styled-content style="fixed-case">BMP</jats:styled-content> results. Therefore, guidelines were set out; yet, these do not provide sufficient information concerning origin of and the microbial community in the test inoculum. Here, the specific contribution of the methanogenic community on the <jats:styled-content style="fixed-case">BMP</jats:styled-content> test results was evaluated. The biomethane potential of four different substrates (molasses, bio‐refinery waste, liquid manure and high‐rate activated sludge) was determined by means of four different inocula from full‐scale anaerobic digestion plants. A significant effect of the selected inoculum on the <jats:styled-content style="fixed-case">BMP</jats:styled-content> result was observed for two out of four substrates. This inoculum effect could be attributed to the abundance of methanogens and a potential inhibiting effect in the inoculum itself, demonstrating the importance of inoculum selection for <jats:styled-content style="fixed-case">BMP</jats:styled-content> testing. We recommend the application of granular sludge as an inoculum, because of its higher methanogenic abundance and activity, and protection from bulk solutions, compared with other inocula.</jats:p>