Anaerobic digestion of wheat straw – Performance of continuous solid-state digestion

In this study the upflow anaerobic solid-state (UASS) reactor was operated at various conditions to optimize the process parameters for anaerobically digesting wheat straw in a continuous process. Additionally, particle size effects have been studied in the operation at 55 and 60 °C. Moreover, the incremental effect of the organic loading rate (OLR) to the system was examined from 2.5 to 8 gVS L−1 d−1. found that the UASS operating at 60 °C with a small OLR yields highest methane production, but the advantage over thermophilic operation is negligible. The rise in OLR reduces the systems yields, as expected. From OLR = 8 gVS L−1 d−1 a second stage is necessary to circumvent volatile fatty acids accumulation.