IMPROVING BIOGAS VOLUME PRODUCTION THROUGH CARBON TO NITROGEN RATIO MODIFICATION OF COW DUNG

This work was performed to study the effect of C/N ratio on biogas volume production. The raw material used was cow dung while glucose and ammonium sulfate was used to modify the C/N ratio. An isolated six-liter container was used to run the anaerobic process where the temperature was kept in a range of mesophilic condition. The container pressure and temperature were investigated daily. In order to boost the biogas volume production, 10% by volume of effective microorganism-4 (EM-4) was added to the substrate (a mixture of cow dung and water with ratio of 1:1). To investigate the effect of C/N ratio of substrate on biogas volume, four different ratios were employed of 15, 22, 27, and 35 respectively. The C/N ratio of the raw material is 22.71. The work showed that the biogas volume increased when C/N ratio of the substrate was high. In the case of C/N ratio of 35, the highest biogas volume was achieved in day 16-18th then the volume decreased gradually. However, the highest volume was achieved in different day for each ratio. For instance in the second best in biogas production, C/N ratio of 27, the highest volume was achieved in day 13-15th and even it was achieved in early day for lower C/N ratios. The results give indication that increasing the C/N ratio of cow dung can improve the quantity of biogas.