Fig. 4

Methanogenic archaea found in biochar particles: after applying the Shapiro–Wilk test (A), a two-tailed paired t-test was used to assess significance for all archaea. Number of methanogenic archaea based on the quantification of cofactor F420 signals (B). Biochar particles from BGP1 were collected from the digestate immediately after it left the digester. Pictures of methanogenic archaea found in biochar particles (C). Methanosarcina-like clusters are highlighted with white arrows