Rice Husk Derived Biomass Briquettes for Boilers: Ingredient-Based Product Quality Study

Abstract

This research investigates the feasibility of repurposing rice husk waste into sustainable biomass briquettes, addressing environmental and economic challenges associated with conventional biomass sources in Sri Lanka. The study involves a comprehensive analysis of rice husk utilization, focusing on three size fractions: original size, particles less than 5mm, and powder form. Rice husks less than 5mm was observed to have a composition of optimal fixed carbon content (11.63% ± 0.215), moisture content (10.53% ± 0.013), volatile matter (80.72% ± 0.005), and ash content (7.65% ± 0.004). The binding agents, namely starch, dummala tree resin, and wastepaper pulp, were used for briquette production. The optimal compositions for briquettes made with rice husk particles less than 5mm were determined as follows: rice husk with starch (1:6), rice husk with tree resin (1:7), and rice husk with wastepaper pulp (1:5). The calorific values of these optimum briquettes were found to be 15.446 MJ/kg for starch-based briquettes, 15.278 MJ/kg for paper pulp-based briquettes, and 15.323 MJ/kg for tree resin-based briquettes. In addition, briquettes made with an equal ratio (1:1) of binders showed calorific values of 14.175 MJ/kg for starch, 14.227 MJ/kg for paper pulp, and 15.275 MJ/kg for tree resin, with tree resinbased briquettes exhibiting the highest calorific value. In the product quality evaluation study carried out with these results, the proximate and ultimate analyses were conducted to characterize the briquettes and the thermogravimetric analysis (TGA) was conducted to characterize the rice husk and to examine the physical properties of the produced briquettes. The findings indicate that repurposing rice husk waste with various binding agents offers a sustainable solution for biomass fuel production. Accordingly, natural tree resin briquettes exhibited the highest density, compression ratio, and shatter resistance. These results suggest that utilizing natural tree resin can effectively address waste management challenges and create an environmentally friendly and economically viable industrial sector in Sri Lanka.