Optimization of Biogas Production from Cassava Peels Mixed with Urea by Central Composite Design Methodology
M.T. Nkodi *
Department of Petrochemistry, Faculty of Oil, GAS and Renewable Energies, University of Kinshasa, DR Congo and Laboratory of Organic Chemistry and Energetics, Department of Chemistry, Faculty of Sciences, Kinshasa XI, DR Congo.
S. J. Kayembe
Department of Chemistry, Faculty of Sciences, DR Congo.
G. Ekoko
Department of Chemistry, Faculty of Sciences, DR Congo.
R. Kizungu
Faculty of Agronomic Sciences, University of Kinshasa, Kinshasa XI, DR Congo and Institut National pour l’Etude et la Recherche Agronomique, INERA, Kinshasa, DR Congo.
M. Mabela
Department of Mathematics and Computer Sciences, Faculty of Sciences, University of Kinshasa, Kinshasa XI, DR Congo.
K. C. Mulaji
Department of Chemistry, Faculty of Sciences, DR Congo.
K. M. Taba
Department of Chemistry, Faculty of Sciences, DR Congo and Laboratory of Organic Chemistry and Energetics, Department of Chemistry, Faculty of Sciences, Kinshasa XI, DR Congo
*Author to whom correspondence should be addressed.
Abstract
The amount of cassava wastes is increasing day by day especially in the developing countries like Nigeria and Democratic Republic of Congo because of the high demand of cassava as food or as raw matter in starch factories. In the both process, 1/3 of wastes is generated from 1 Kg of cassava tubers which could be used as substrate to produce biogas which is the renewable energy to decrease oil dependence and therefore atmospheric pollution depletion. The present study aims to know the optimal conditions for biogas production from biomethanization of cassava peels mixed with urea in mesophilic conditions during 14 days in sixteen reactors of 1 Litre capacity, using response surface methodology (RSM). Two parameters were studied, organic loading rate (OLR) and urea concentration (UC). The variations used for OLR was 5% and 15% TS and for UC, it was 0.01 % and 0.05 %. The variations obtained inside were determined by Central Composite Design (CCD) made from rsm package of R software 4.1.1. Based on experimental results analysis, it was found that urea concentration affect biogas production (P<0.05), the optimum value of Organic Loading Rate and urea concentration were 6.688%TS and 0.0067% respectively, with a optimal biogas yield of 3260.694 mL. The analysis of variance (ANOVA) showed a high coefficient of determination value (R2=0.8146) at 95% confidence level and a p-value of 0.002. The results show that urea concentration has a major impact on biogas production (P<0.05).
Keywords: Optimization, biogas, cassava peels, urea, central composite design