Physicochemical Characterization of Wood Mixed with Coffee Waste Pellet

Abstract

Recently, the demand for wood pellets as solid biofuel for co-firing process in the industry has increased. However, the increase in demand is not accompanied by the availability of sawdust (SD) as a raw material. Thus, seeking alternative biomass is needed to substitute wood. One of the alternative biomasses that can be considered as raw material for bio-pellet is the solid waste from the coffee industry. Meanwhile, the coffee industry annually produces large amounts of organic waste such as spent coffee grounds (SCG) and coffee husks (CH). Both solid wastes have organic compounds contained so that they can be utilized as solid biofuel. In this research, We investigated the quality changes of wood pellets before and after the addition of coffee waste in different mass ratios (1:1, 1:3). A densification method with a pressure of 2 tons is used in the wood pellet-making process. Physicochemical characterization of wood pellets such as density, durability, compressive strength, calorific value, and proximate and composition analysis using SCG and CH are conducted. The result shows that the addition of SCG into wood pellet increased the calorific value of wood pellet from 21.03 MJ.kg-1 to 21.71 MJ.kg-1. The calorific value with a ratio of 50: 50 of SD: SCG produces a better calorific value than CH (20.64 MJ.kg-1). The mechanical test of the pellet shows that the addition of SCG and CH slightly decreases the mechanical durability from 99.34% to 97.02%. Thus, increase the appearance density from ρ = 892.46 kg.m-3 to ρ = 1119.33 kg.m-3.