Generation of Biogas from Cow Dung.

Abstract

Four sets of 250 ml conical flasks (A-D), each containing two flasks, were used in triplicates as digesters to determine the possibility of laboratory-scale biogas production from cow dung under four different treatments. Equal volumes of slurry (3 g dung: 10 cm3 water) in the digesters were subjected to anaerobic digestion over a four-week retention period, with weekly measurements of gas yields. Gas was collected by the water displacement method. Flasks A were kept at ambient temperature (25 ± 2°C) and gas was collected over water. The B-flasks were also kept at ambient temperature but gas was collected over lime water. Flasks C were exposed to sunlight outdoors. The D-flasks were kept at 40°C. At the end of the digestion, microbial analyses of the spent slurry were carried out. Gas was produced in digesters A, B and D. The B digesters had the highest total gas yield (15.60 cm3). Differences in total gas yield were significant (p<0.05) for the different treatments. Gas production increased with increase in retention time. Week 4 had the highest percentage gas yield (53.85%) for the B digesters. For the A and D digesters, week 3 and week 2 had the highest percentage gas yields of 41.30% and 39.29%, respectively. The microbial isolates included Bacillus licheniformis, Escherichia coli and Clostridium sp. Cow dung demonstrated a potential for biogas generation.