Present state of wood waste recycling and a new process for converting wood waste into reusable wood materials

Abstract

The amounts of new wood used for housing construction and wood waste from demolished buildings was calculated using various scenarios of wood recycling. Diverse utilization of waste and increase in reuse rate was found to be effective to reduce the total amounts of final waste and the use of new wood materials. For recycling wood waste, the water vapor explosion (WVE) process was developed. In this process, wood materials were exploded from within by the force of water vapor generated by compression under high pressure and temperature and evaporation of the internal moisture, and they were separated into small wood elements. The WVE process was directly applied to the separation of Sugi (Cryptomeria Japonica) and Karamatsu (Laryx leptolepis) sawn timbers and slabs. The WVE of them produced small wood elements including fiber bundles, strands, and chips at certain experimental conditions (pressure, temperature, and compressing time). Fiber bundles were long, narrow and flexible elements, and it appeared that they could not be obtained by the conventional processes.