Briquettes From Solid Waste: A substitute For Charcoal in Burundi

In Burundi, the problem of solid waste management is acute as dependence on wood and charcoal as solid fuel is creating a major problem of deforestation [1]. The purpose of this work is to promote material and energy valorization of solid waste in Bujumbura where a preliminary study has been realized showing the inventory with the composition and the quantification of MSW (0.6 kg/day.capita). The present work is especially devoted the characterization of the briquettes made by using specific solid waste in a process developed by Bioernergy Burundi enterprise [2]. A random sampling of 3 briquettes from a 5kg package is used for the determination of their characteristics to meet the criteria to be used as solid fuel substitute. Materials to be characterized in this work are briquettes manufactured by Bionergy Burundi Enterprise [2] and their ashes. The process is using a specific solid waste mixture. The mixture consists of residues of charcoal, dry Eragrostis grass, sawdust and wood shavings from the furniture manufacturing workshops, rice hulls from the husking units and MSW (partially sorted). The mixture, in well-known proportions of the listed waste, is then heated (mainly dried), milled and introduced into a mould to produce the briquettes (L~20 cm and Φ~ 7cm). Results on proximate analysis of the briquettes are detailed in this work. The mean humidity content is in the order of 20%. Results on dry matter show an ash content of 44%, a high volatile matter of 42%. The value of the fixed carbon content is presented and is very depended on the sampling method. Fixed carbon content lies between 13% and 26%. The calorimetric bomb method (ISO 1928) has been used to evaluate the gross calorific value. The lower calorific value is then calculated (LCV~11 MJ/kg). On the other hand, to be able to use safely the briquettes as substituted solid fuel, further investigation was made to evaluate the presence of pollutants. XRF and XRD measurements were performed on the briquettes and their ashes respectively. Elemental analysis and detection of crystallized compounds are presented showing only traces of pollutants. The main conclusion of this work is that preliminary results on Bioenergy Burundi briquettes are encouraging and would incited to consider this path for the valorization of some solid waste as substitution solid fuel for charcoal. Currently, in the city of Bujumbura, energy needs for a growing population are real and the use of these briquettes as a substitution solid fuel could be one of the alternate routes.