Local variability of yield and physical properties of acai waste and improvement of its energetic attributes by separation of lignocellulosic fibers and seeds

Abstract

The high degree of variability among suppliers and types of biomasses hinders their application in energy production. Investigation into this drawback is needed for the use of the waste produced from açaí depulping, which is widely available throughout the Amazonia. This work aimed to analyze the variability of the yield and physical properties of the açaí waste among different Amazonian producers located at Macapá, AP, Brazil. In addition, energetic attributes of different waste components, namely, seeds and lignocellulosic fibers, were compared to determine if they should be separated prior to burning or pyrolysis. The average yield (71.0%–95.0%), dry basis moisture content (66.6%–76.2%), and basic density (0.753 g cm−3 to 0.812 g cm−3) of açaí waste varied remarkably among the suppliers. Fibers and seeds depicted similar higher heating values (19.91 MJ kg−1 and 19.32 MJ kg−1) and fixed carbon (21.39% and 21.50%) and volatile matter (77.32% and 76.65%), while the ash content was slightly lower for seeds (1.29%–2.08%) in comparison to fibers (1.85%–2.63%). Thermogravimetric analysis revealed different initial degradation temperatures and mass loss rates for the seeds and fibers. It was concluded that the yield and physical properties of açaí waste varied remarkably among providers. A drying process should be carried out before açaí waste burning due to its high moisture content. The high basic density is an advantageous feature of açaí waste in the context of bioenergy. Separation of the components is recommended prior to pyrolysis to avoid heterogeneous charcoal.