Thermal behaviour of viscosity of aqueous cellulose solutions to emulate biomass in anaerobic digesters

Abstract

With the establishment of biogas technology as an important renewable energy producer, it is necessary to optimize the biogas generating process. To realise the highest efficiency, it is essential to minimise energy consumption, which is mostly due to the stirring of biomass slurry. Laboratory-based studies are economically and practically preferred over investigations of industrial scale biogas plants. The use of a valid surrogate to replace real biomass in scientific laboratories is a strategic approach to simulate reality. In this study aqueous cellulose solutions are examined. Rheological properties at varying temperatures and concentrations are analysed using the Ostwald–de Waele model for non-Newtonian fluids. The results are evaluated against data obtained with real biomass used in biogas plants. It is concluded that the rheological behaviour of sludge can be mimicked using water–cellulose solutions of 0.3 wt% at 20 °C in a 1 : 12 scaled-down laboratory digester.