Characterization of briquettes developed from water hyacinth and groundnut shell blends-The case of Lake Tana

Abstract

Background Ethiopia’s energy relies mainly on biomass sources, residues of crops and animal dung collections. Over 90% of domestic energy needs in Ethiopia are met by biomass, which contributes to deforestation and climate change. This study investigates the usage of water hyacinth and country’s largely produced agricultural waste (groundnut shells) for the production of briquettes using potato peels as a binder. Methods Water hyacinth, groundnut shells, and potato peel waste were used for production of briquettes. Briquettes were prepared using three parameters; temperature (350 ℃, 450 ℃ and 550 ℃), particle size (0.5, 1 and 1.5mm) and mixing ratio (25%, 50% and 75%). Physical properties and calorific values for the developed briquettes were determined using FTIR machine and bomb calorimeter. Central composite design by the design expert was used to design the experiment, and response surface methodology was used to optimize the calorific value of the produced briquettes. Statistical analysis tool such as analysis of variance was employed to show whether the process variables were statistically significant on the response variable (P < 0.05). Results The developed briquettes had the highest calorific value, 25.52 MJ/kg. The maximum bulk density and durability of the produced briquettes were 0.553% and 97.86%, respectively. The moisture content, volatile matter, ash content, and fixed carbon content of water hyacinth biomass were 8.14%, 68.49%, 10.3% and 13.06%, respectively. The moisture content, volatile matter, ash content, and fixed carbon of the groundnut shells were 9.2%, 66.84%, 3.615% and 20.34%, respectively. The produced briquettes had a moisture content ranging from 8.470–11.760%, and ash content ranging from 5.850–8.750%. Temperature, particle size and mixing ratio were statistically significant on the calorific value of the briquettes (p < 0.05). The optimised briquettes have a calorific value of 24.544 MJ/kg, at a temperature, particle size and mixing ratio of 453.380℃, 0.999 mm, and 50%, respectively. Conclusion The produced briquettes had good calorific value, bulk density and durability, and were suitable for cooking and heating purposes. This revealed that agricultural wastes could be used to augment the energy sources pool to protect the environment and create social stability in the community.