LAUSR

Abstract Empty fruit bunch (EFB) has a high potential to be utilized as energy source. This study investigated the effects of the hydrothermal treatment and pelletizing temperature on the physical properties of the EFB pellets. EFB was hydrothermally treated using 10 m3 batch-type reactor and water washed using a centrifugal machine. Single pellet making device was used for pelletization of both treated and untreated EFB. The pellets were densified at a pressure of 60 MPa and a temperature of 100, 150 and 200 °C by using a single pelletizer. The pellet density, the compressive strength, the hydrophobicity and the durability of the produced pellets were evaluated. In addition, scanning electron microscope (SEM) was also utilized to examine the binding mechanism and its quality. The results showed that combination of hydrothermal treatment and water washing significantly improved the physical properties of EFB pellets especially, at the pelletizing temperature of 100 °C. At the pelletizing temperature of 100 °C, the pellet durability index (PDI) and compressive strength of untreated EFB pellet increased from 78.1% and 5.6 MPa to 98.72% and 15.6 MPa, respectively when compared to the treated pellet. Notable increase in pellet properties of untreated EFB were also observed as pelletizing temperature increase. At pelleting temperature of 200 °C, PDI and maximum load to 92.83% and 14.2 MPa respectively. However, only slight improvement in characteristics of the washed hydrochar pellets were observed as the pelletizing temperature increased. Finally, the energy balance in the process of EFB-to-Pellet was roughly calculated for the commercialized system, and the output energy in pellet products could reach 89.90%.