Development of devices for the determination of the rheological properties of coarse biomass treated by dry anaerobic digestion

Abstract The lack of rheological characterization of coarse biomass limits the design, operation and optimization of continuous Dry Anaerobic Digestion (D-AD) processes. In this work, three alternative rheological devices for the determination of rheological behavior of coarse biomass were scale-up and calibrated; the slump test, the consistometer and the shear-box. The applicability and limitations of each device were evaluated using artificial mixtures of straw-cattle manure prepared using raw and shredded Wheat Straw (WS). The slump test and consistometer results suggest that the yield stress increases exponentially from 43 to 882 Pa with the WS content increase, reducing the flowability. Cohesion and friction angle measures using the shear-box were between 1.39 and 3.17 kPa and 11.0 and 28.89° respectively. This work represents an advance in the setting-up of standardized methods to the rheological determination of coarse biomass.