Preliminary Study on Co-Digestion of Cow Manure with Pretreated Sawdust for Production of Biogas and Biofertilizer

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Author(s) Akwaka, J.C. | Kukwa, D.T. | Mwekaven, S.S.
Pages 222-228
Volume 3
Issue 4
Date April, 2014
Keywords Co-digestion, pre-treated sawdust, cow manure, digester, biogas, biofertilizer

Microbial digestion of the combined matrix of cow manure (CM) and pre-treated sawdust (PS) yielded biogas significantly. The sludge left behind was assayed for its nutritional composition as recyclable plant nutrients using standard methods. Analysis showed that dry mass of undigested raw material contained N (0.85%); P (0.41±0.01g/kg); K (1.21±0.11g/kg); Ca (0.64±0.02g/kg); Na (0.04±0.01g/kg); Mg (0.37±0.13g/kg); Fe (0.55±0.01g/kg); Zn (0.03±0.01g/kg). For the sludge, analysis showed N (3.26%); P(1.64±0.03g/kg); K (3.45±0.04g/kg); Ca (1.93±0.11g./kg); Na (0.18±0.01g/kg); Mg (1.02±0.05g/kg); Fe (1.25±0.12g/kg) and Zn (0.07±0.02g/kg), respectively. There was a significant difference (p<0.05) in height of maize grains planted on both sludge-fortified and unfortified samples of loam, with other conditions being the same. Maize grains planted on sludge-fortified loamy soil recorded a mean height of 198mm after 2 weeks of monitoring while those planted on unfortified soil gave a mean height of 110mm for the same period. Mineral content analysis of the sludge clearly showed that it could serve as a good organic fertilizer. The researchers concluded that coupling of pretreated sawdust into the cow manure anaerobic digester not only enhanced fuel gas production, but also gave nutrients-rich residues for re-cycling to the land.

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