Valorization of green tea waste from ready-to-drink industry through pelletization and use as solid fuel

Abstract

The production and characterisation of pellets made from green tea waste from the ready-to-drink industry is investigated in this study. Physical and energetic characterisation of pellets including the length, diameter, proximate analysis (moisture, ash, volatile matter and fixed carbon content), pellet density, bulk density, calorific value, durability, compressive strength and thermogravimetric analysis were carried out to determine the quality of the bio-based fuel pellets. Pellet properties were assessed against comparison with the established Thailand and European standards. Pellet making was conducted with a hydraulic press without binder resulting in pellets with 2 diameters, 7 and 10 mm, and lengths of about 9.5 and 9.8 mm, respectively. The interesting characteristics of these biopellets were the moisture content of 8.78 – 8.82 wt%, the ash of 3.52 – 3.65 wt%, the bulk density of 586 – 603 kg/m³ and higher heating value of 19.18 – 19.86 MJ/kg. In addition, the pellets produced with both diameters had properties that complied with the standards except for the bulk density of large pellets which were slightly lower. The durability of the 7 mm diameter pellets was 90.2% while 10 mm pellet was 95.6%, which a bit lower than standard value (≥ 96%). The pellet’s compressive strengths in vertical direction were much higher than horizontal direction for both diameter pellets. These results suggest that this biomass waste was suitable for alternative fuel applications and has the potential to be developed as a commercial pellet.