Comparative study of co-digestion of composted mixtures of cassava peels and coffee pulp with or without cow dung.
Authors: Nkodi* T.M1, Kayembe J.S2., Biey M. E 3.and Taba K.M2
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This work aims to study co-digestion of composted mixture of cassava peels and coffee pulp with cow dung .Cassava peels was mixed with coffee pulp in the following ratios by weight, 1:1, 3:1, 1:3, Cassava peels alone (1:0) and coffee pulp alone (0:1) served as controls. The mixtures and controls were submitted to composting for 30 days then placed in five digesters C1 for 1:1 blend,C2 for 3:1 blend,C3 for 1:3 blend , C4 for cassava peels alone and C5 for coffee pulps alone. Another batch of five digesters consisting of each composted mixture of cassava peels and coffee pulps to which was added equal amount of cow dung labeled as follows: CB1, CB2, CB3, CB4 and CB5. Biodigestion was conducted under mesophilic conditions into 5L biodigesters with a loading rate of 5% of total solids. Biogas production was measured by using water displacement method for 35 days. The highest cumulative volume of biogas was produced by composted mixture with cow dung and the yield decreased in the following order 16.50, 15.38, 15.07, 12.68 and 10.97L/KgTS respectively for CB3>CB1>CB5>CB2>CB4. The composted mixture alone yielded the following amount of biogas: 10.26, 9.11, 8.86, 7.50, and 7.07L/KgTS respectively for C1, C5, C4, C3 and C2. Co-digestion of the composted mixture of cassava peels and coffee pulps with cow dung can be considered as a good system to enhance biogas production from cassava peels.