Assessing the Effects of Substrate Disintegration on Methane Yield

Data obtained from seven lab‐scale experiments were used to compare different methods for describing effects of substrate disintegration on methane yield. Statistical evaluation underlines the importance of careful design and precise conduction of experiments. Within continuous experiments conducted as duplicates, an effect 5.65 times (triplicates: 3.07 times) the standard deviation between identically operated digesters can be considered significant. Some tests show significant impacts; however, the results between different test approaches, namely, batch, continuous digestion (measured), and continuous digestion (modeled from batch tests), are inconsistent. This inconsistency hints at a limited transferability from batch results to continuous operation in general and for the effect of disintegration in particular. Statistical analysis of seven anaerobic digestion experiments for investigation of disintegration effects proved that enzymatic disintegration had no major effect on methane yield, whereas mechanical‐chemical and thermophysical disintegration changed the methane yield significantly. The inconsistency between different tests hints at a limited transferability from batch results to continuous operation.