Fig. 2
From: Monitoring of seven industrial anaerobic digesters supplied with biochar
Evolution of organic acid concentration upon biochar supplementation: after normalization to a value between zero and one, mean values were calculated for all seven digesters (BGP1–BGP7). Concentrations were recorded over a duration of one year. The significance of the decrease in organics acids was assessed for acetic acid (A), propionic acid (B) and butyric acid (C) applying a nonparametrical Spearman test