Improving biogas production from animal manure by batch anaerobic digestion

Abstract

In Libya, even if the production of biogas started in the last years, still there is too much need to optimize the biogas resources. This paper examined improving cow, sheep, and poultry manure in two phases. The experiment was carried out in a 2000 mL digester put in bath water at 37 °C. The mixing ratio of animal manure and water used was 1:1 in 12 days of Hydraulic Retention Time (HRT). The produced gas was measured by the volumetric water replacement method. In the first phase, the best pH was chosen in the experimental test with different pH ranges. Three set-ups were prepared with different pHs (6.5, 7, 7.5). The results showed that the pH had significant effects on biogas yield, where pH 7 had the highest biogas production and pH 6.5 had the lowest. In the second phase, the effect of insulation of digester on the biogas yield of cow, sheep, and poultry manure was investigated. The experiments showed that the biogas produced from an insulated digester was higher than the transparent digester. Therefore, it is assumed that the study, which gives a maximum yield of biogas production from the batch digestion process, might meet future energy demand.