Abstract

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This study was carried out to examine the catalytic effects of Single Super Phosphate (SSP) with Wood ash on the production of biogas from Cow Dung. The study was carried out in four identical reactors to enable variation of the catalyst combination (100gSSP/50gWoodash, 150gSSP/75gWoodash and 200gSSP/100gWoodash). The research showed that SSP and Wood ash could reduce the lag phase in anaerobic digestion of cow dung. The control which was Cow dung digested without any catalyst had the longest lag phase of 7.5 days as compared to 5.9 days for those digested with catalyst. At the end of 32 days digestion period, total volume of biogas produced across the digesters were 0.0906m3 (no catalyst), 0.0973m3 , 0.0937m3 , and 0.1141m3 (200gSSP/100gWood ash), which indicated an increment with increase in catalyst. The Modified Gompertz equation was applied to describe the cumulative biogas generation. The Biogas production Kinetic Constants estimated by the linear regression method using the solver function in Microsoft Excel as well as other characteristics obtained for the four digesters were 0.0037m3 /day 0.0036m3 /day 0.0045m3 /day and 0.0056m3 /day for Biogas Production Rate and 0.0893m3 , 0.0841m3 , 0.0977m3 and 0.1188m3 for Biogas Production Potential. The average temperatures of the digesters recorded were 35.20 oC, 35.30 oC, 35.17 oC, and 35.18 oC respectively while the average ambient temperature observed during the study was 36 0C which were within the mesophilic range.

Keywords: Biogas, Cow Dung, Single Super Phosphate, Wood ash, Modified Gompertz equation