Quantifying porosity changes in solid biomass waste using a disruptive approach of water retention curves (WRC) for dry anaerobic digestion

Abstract Knowledge of the porosity distribution of biomass is crucial to understand the liquid flow through porous solid biomass treated in dry anaerobic digestion (D-AD). In this study, a novel adaptation of Water Retention Curve (WRC) analysis was validated to characterize the pore distribution of representative lignocellulosic biomasses; Cattle Manure (CM), roadside grass and corn stover. WRC analysis is composed of a drainage analysis (DA) and thermogravimetry analysis (TGA). Macro, meso and micropores values ranged from 33 to 63%, 25 to 44% and 7 to 16% for listed raw biomasses. Additionally, changes in porosity distribution of CM treated in sacrificed Leach-Bed Reactor (LBR) were quantifying; macropore volume decreased from 30.4 to 1.7% with the fiber degradation reducing considerably the permeability and increasing the solid bed compaction. The findings of this study suggest that the daily recirculated liquid volume could be progressively adapted considering the physical evolution of the solid bed.