Physico-chemical properties and thermal degradation characteristics of agropellets from olive mill by-products/sawdust blends

• Agropellets were produced from olive mill wastes blended with pine sawdust.
• Physicochemical characteristics of the agropellets could reach French standards.
• Thermogravimetric analyses show higher reactivities for PS/OW pellets.
• The use of blend sawdust/olive mill wastes may be an attractive biofuel.

This study aims to produce agropellets composed by olive waste, an olive mills by-product, blended with pine sawdust for 6 different mass fraction compositions. Thermal and physicochemical properties of these pellets such as moisture, ash content, bulk density and heating values were determined. In addition, thermogravimetric analyses were performed under inert and oxidative atmosphere in order to assess the thermal degradation behaviour of the produced agropellets. Results show that during the pelletization process, the high value of moisture in olive waste decreases. Values of ash content for each considered sample remain in the accepted agropellets French standards. Thermogravimetric analysis shows that the thermal degradation of the different pellets follows the usual behaviour of lignocellulosic materials. Furthermore, a quite continuous zone corresponding to the not readily char combustible part is detected during TGA under oxidative condition. However, a higher reactivity for PS/OW pellets is observed compared to those reported in literature. Such results prove that olive waste agropellets may be an alternative fuel for producing energy in domestic boilers.