Nitrogen removal of ramie stalk treated by acid wastewater combined with Clostridium thermocellum and the kinetic study of pyrolysis

► Straw may contain high nitrogen which should be removed before energy utilization. ► Acid combined with bacterium can remove nitrogen from biomass effectively. ► Wastewater from bioleaching is more suitable than H2SO4 in the treatment. ► The treatment is fast, cheap, efficient and feasible. ► Pyrolysis kinetics shows the treated straws are suitable for gasification.