BIOMASS， THERMAL PRESSURE HYDROLYSIS AND ANAEROBIC DIGESTION

A process is provided for preparing a low density， fibrous primary lignocellulose biomass， particularly straw for anaerobic digestion at large scale， i.e. >2 MW th， which comprises a step that greatly increasing the density of the straw through size reduction， moisture adjustment and compression ahead of loading and subsequent agitation of the resultant biomass in a pressure vessel through an atmosphere of saturated steam providing heat for thermal-pressure hydrolysis and recovering treated biomass from the vessel. The primary lignocellulose biomass may be prepared in admixture with secondary biomass which may be manure-based. There is also provided a feedstock for anaerobic digestion comprising a fibrous primary lignocellulose biomass in a finely divided state， a secondary biomass providing anaerobically digestible nitrogen and aqueous liquid， the primary biomass having a disrupted cellular structure such that its inherent buoyancy in aqueous liquid is lost and digestible carbon is released and the mixture being in the form of an aqueous slurry in a sterilized state. The feedstock after thermal pressure hydrolysis may be anaerobically digested e.g. by wet mesophilic anaerobic digestion to achieve a high unit throughput and biomethane output thus allowing the deployment of the system at large scale within the anaerobic digestion industry.