Title: Towards a sustainable use of food waste: influence of urea on biogas production potentials of selected fruit wastes in Addis Ababa, Ethiopia

Authors: Getachew Dagnew Gebreeyessus; Berhanu Assefa Demessie

Addresses: Haramaya University, P.O. Box 235, Harar, Ethiopia ' School of Chemical and Bioengineering, Addis Ababa institute of Technology, P.O. Box 385, Addis Ababa, Ethiopia

Abstract: This study evaluates the influence of adding urea on biogas (methane) production potentials of selected fruit wastes. Using standard methodology, the finding revealed that all the fruit wastes are ideal substrates for biogas production. The ultimate biogas yield on anaerobic digestion of fruit waste feeds, avocado, banana, and mango, are 0.48, 0.57, 0.53 l/g VS without urea supplement and 0.76, 0.82, 0.82 l/g VS with urea supplement, respectively. Thus, urea addition improved significantly the biogas yield. However, volatile fatty acids, alkalinity and pH follow-ups showed rapid acidification partly in digesters. The ultimate CH4 percentage did not show significant difference in response to urea supplement. It gave 0. 27, 0.33, 0.27 l/g VS without urea supplement and 0.44, 0.46, 0.43 l/g VS with urea supplement on anaerobic digestion for avocado, banana, and mango fruit wastes, respectively.

Keywords: fruit waste; urea supplement; biogas yield; methane; volatile fatty acids; VFAs; Ethiopia; sustainable development; sustainability; biogas production; anaerobic digestion; avocado; banana; mango; alkalinity; pH; acidification.

DOI: 10.1504/IJESD.2014.060200

International Journal of Environment and Sustainable Development, 2014 Vol.13 No.2, pp.172 - 184

Available online: 31 Mar 2014 *

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