PRODUCTION OF BIOGAS USING COW DUND, GRASS CUTTINGS, PIG WASTE

ABSTRACT

This study comparatively analysed biogas production from three waste materials: Grass - Axonopus compressus, cow dung and pig waste slurry, with respect to the effects of carbon/nitrogen (C:N) ratio on biogas yield. A mixing ratio of 1:10 (one (1) part of substrate to ten (10) parts of water) was used. Nine 2L plastic digesters, were used for the study. Digestion was carried out in triplicates, 3 digesters for each substrate. The C:N ratios of the substrates were as follows:  Axonopus compressus (24:1), pig waste slurry (17:1), cow dung (33:1). The volume of gas produced was determined by water displacement method. The average temperature that prevailed during the digestion process had pig waste slurry having the highest and Axonopus compressus having the lowest as follows: 32.67oC > 30.99oC > 19.97oC. Results showed that pig waste slurry had the highest total average biogas yield while the mixture of cow dung and pig waste slurry had the lowest as follows: 377.46ml > 281.31ml > 185.16ml. However, these results were statistically significant at p < 0.05.