Characterization of pellets from mixing olive pomace and olive tree pruning

Olive pomace is an interesting agro-industrial byproduct that can be a potential raw material for densified biomass products. At first, 2-phase (2 PH) and 3-phase (3 PH) olive pomace pellets were analyzed in order to evaluate their quality in terms of the main parameters required by the European Standard EN 17225-6. The characterization of the pure pellets has shown important problems because of out of limits values of nitrogen, durability and copper in the two olive pomace. To improve the properties of olive pomace pellets, the possibility of manufacturing pellets by mixing olive pomace and olive tree pruning (PR) was investigated. Several blends at different weight ratios were analyzed in order to verify the effect of mixing on the pellet properties. It can be concluded that the physical properties of all mixtures are in compliance with the requirements of the standard. In particular, two best blends in terms of physical, chemical and mechanical characteristics were identified as becoming potential fuel for combustion and gasification applications: 75PR252 PH (75% pruning and 25% 2-phase pomace) and 50PR503 PH (50% pruning and 50% 3-phase pomace).