Analysis of Bio-gas Production from Cow Dung by Indigenous Microbial Consortia

Abstract

The study analyzed quantitatively and qualitatively the biogas produced from cowdung by indigenous microbial consortia. Four 20L bioreactors were used for the study. The bioreactors were constructed to imitate the fixed batch prototype. The study lasted for six months and it was carried out at the Microbiology Laboratory of Anambra State University, Anambra State, Nigeria. Slurry was prepared in bioreactors. The substrates in the bioreactors were water and manure (WM), rumen fluid and manure (RM-1 and RM-2), medium and manure (MM). The pH, the total solids (TS), volatile solids (VS) and total volatile fatty acid (VFA) characteristics of the substrate before and after digestion were determined using standard method. Quantification and qualitative analysis of biogas production was by liquid displacement and gas chromatography methods respectively. The microbial analysis of the substrate was carried out using spread plate method. The results of the TS, VS and VFA were 400 mg/l, 92mg/l and 16.7 mg/l respectively in the predigested samples and 92 mg/l, 17.4mg/l and 28.3mg/l respectively in the post digested samples. The quantity of biogas produced at fourth month was 60 ml, 128ml and 220ml from WM, MM and RM-1 respectively. The qualitative analysis showed that the prominent biogas produced was methane. The cultural morphology revealed Gram positive rods with creamy irregular edges. The average heterotrophic counts at the end of each month for a period of four months were 18.5x105cfu/ml, 21.1 x105cfu/ml and 26.7x105cfu/ml for WM, MM and RM respectively. The results of the research concluded that high quantity of biogas can be produced using cow dung. Approaches and technology for more efficient biogas producing consortia are proposed.