Effect of rumen content to water ratio in biogas production

Abstract

Biogas technology is widely used as a better alternative in the handling of waste in many societies in the world. This study was conducted to investigate the effect of rumen content to water ratio in biogas production. An experiment was carried out using 75 litre capacity locally made anaerobic digester. Rumen contents were formulated in three proportions designated as T1, T2 and T3. T1 contained 30kg of rumen contents and 30 litres of tap water; T2 contained 20kg of rumen contents and 40 litres of tap water; and T3 contained 40kg of rumen contents and 20 litres of tap water. Each proportion was duplicated and the whole experiment was triplicated for 20 days each. The pH, substrate, ambient temperatures and the biogas produced were recorded in two days’ interval up to the 20 days. The result obtained from the study showed that there were significant differences (P < 0.05) in the average pH and the biogas produced. The pH of T2 (6.97) was significantly higher than that of T1 (6.80) and T3 (6.81). The biogas produced by T3 was significantly higher than that of T1 and T2. T3 produced the highest average volume of 16.70m³ biogas per kilogram of rumen content and the highest percentage (56.4%) of methane. There were no significant differences (P > 0.05) in the average substrate and ambient temperatures, and the volume of CO₂ produced. This study revealed that it is more efficient to produce biogas using 40kg of rumen contents and 20 litres of tap water than producing biogas with 30kg of rumen contents and 30 litres of tap water or 20kg of rumen contents and 40 litres of tap water.

Keywords: biogas, pH, rumen, temperature, water