Study of the Evaluation of the Biogas Potential of Waste from the Agricultural Farm of Denken in Boke, Republic of Guinea

Abstract

In rural and suburban areas of Guinea, waste and organic residues generated by agricultural and agro-industrial activities are traditionally valued in situ in animal feed as provender, in soil fertilization and for energy purposes as fuel. This work puts a cent on the opportunity of a better recovery of this agricultural waste by methanization. The adopted method consists in: quantifying the biodegradable waste of the farm; determine the physicochemical characteristics of these various methanizable wastes and assess the biogas potential of these wastes. The main results obtained are: The average annual quantities of waste produced on the farm are: cow dung 400 tons, stubble or rice stalks 40000 tons and rice husks 2700 tons; physicochemical parameters: (<i>i</i>) cow dung: Humidity (64%), Dry Matter (36%), Organic Matter (65%), density (203kg/m³), Carbon content 38% and carbon content Nitrogen (1.71%), (<i>ii</i>) rice stubble: Moisture (27%), Dry Matter (73%), Organic Matter (51%), Density (193 kg/m³), Carbon (30%) and Nitrogen (1.95%); (<i>iii</i>) rice husk, Moisture (16%), Dry Matter (84%), Organic Matter (36%), Density (163 kg/m³), Carbon (21%) and Nitrogen (1.46%); cumulative production of biogas in co-digestion: cow dung (0.066 m³), rice stubble (0.039 m³) and rice husks (0.042 m³); the cumulative production of biogas in co-digestion: rice stubble with rice husks (0.0437m³), cow dung with rice husks (0.0482 m³), cow dung with rice husks (0.0711 m³) and cow dung cow with rice stubble and rice husks (0.0808 m³); the pH varied from 7 to 8.5 in cow dung, rice stubble and codigestion substrates and from 6 to 8 in rice husk, respectively. During the 45 days of the process, the digestion temperature in the different digesters varied from 24 to 31°C with averages varying from 26°C to 28°C. The results of this study show the importance of the diversification of organic matter for the optimal production of biogas, which also makes it possible to locally mitigate methane emissions from livestock and crops in Agricultural farms.