Carbonized and Non-Carbonized Composite Briquettes Developed From Cow Dung and Coffee Husks Agricultural Wastes

Composite carbonized and non-carbonized briquettes were developed from cow dung (CD) and coffee husks (CHs) under both dry and wet conditions. The performance of these composite briquettes was compared to that of composite briquettes developed using typical cassava starch as a binder. Mechanical and thermal properties of the developed composite briquettes were determined to ascertain the performance of the composite briquettes. Proximate analysis results ranged between 9.6%–17.7%, 18.8%–31.6%, 15.9%–44.6%, and 17.8%–43.3%, for moisture, ash, fixed carbon, and volatile matter, respectively, for the composite briquettes. Composite briquettes with 12% dry CD biochar and 80% CHs biochar had the highest calorific value of 19.76 MJ/kg. The highest drop strength was observed for composite briquettes with 30% wet CD and 70% CH biochar. Composite briquettes developed from 12% CD biochar and 80% CHs biochar had the highest water absorption rate. The thermostep non-isothermal gravimetric analyzer (TGA) and derivative thermogravimetry (DTG) curves showed typical thermal decomposition of cellulose, hemicellulose, and lignin for the developed composite briquettes. The results show that wet CD, which is typically a waste material and a potent source of methane gas, is an effective alternative binding agent to cassava starch, which is a source of food, in the development of composite briquettes.