Factors affecting mechanical properties of biomass pellet from compost.

Effectiveness of a densification process to create strong and durable bonding in pellets can be determined by testing the mechanical properties such as compressive strength (CS) and durability. Mechanical properties of pellet from composted municipal solid waste were determined at different raw material and densification conditions. Ground compost samples were compressed with three levels of moisture content (35%, 40% and 45% (wb)), piston compaction speed (2, 6 and 10 mm/s), die length (8, 10 and 12mm) and raw material particle size (0.3, 0.9 and 1.5mm) into cylindrical pellets utilizing opened-end dies under axial stress from a vertical piston applied by a hydraulic press. The effects of independent variables on mechanical properties were determined using response surface methodology based on Box-Behnken design (BBD). All independent variables affected the durability significantly. However, different piston speed and die length not produce any significant difference on CS of pellets. Also in this research the electron photography method was used to identify the binding mechanism of compost particles.