A number of different wood raw materials are used for particleboard production, ranging from logs to sander dust. The use of agricultural and industrial residues to replace wood as raw materials for particleboard has received considerable attention in recent years (Wang and Sun, 2002 and Papadopoulos and Hague, 2003).
There are different process lines for particleboard production. One of them is a production line using a combination of wood fibers (on the surface) and wood particles (in the core) (Maloney, 1977). As mentioned before, paper sludge is mainly composed of fibrous fines; therefore, it may have potential application in particleboard production as an alternative to wood fiber. The process of particleboard production with paper sludge as a surface layer is similar to that of particleboard production using a combination of wood fibers and wood particles. Some pre-treatments, such as removing inorganic materials and dirt from paper sludge, may be important before use in particleboard production. Fig. 2presents a diagram of three-layer particleboard production with paper sludge as a face layer.