PERFORMANCE OF ANAEROBIC DIGESTION OF PHYSICAL AND BIOLOGICAL PRE-TREATED COW MANURE FOR METHANE GAS PRODUCTION

Abstract

Cow manure (CM) has the potential to produce the highest biogas potential compared to other types of ruminant wastes however the presence of lignin in CM limited the accessibility of microorganisms, thus reducing the hydrolysis rate to produce biogas. The purpose of this research is to derive the best method in biogas production from CM. To achieve this, three phases of study were performed. In the first phase, a batch study of anaerobic digestion of CM was carried out for 30 days at 35 °C and the lignin degradation potential in CM after addition of A. fumigatus SK1 were evaluated. In this phase, the addition of A. fumigatus SK1 increased the lignin degradation thus improving the hydrolysis process. The second phase was the evaluation of biomethane potential of CM through physical and biological pre-treatments. Dry grounded (DG) pre-treatment process produced 0.22 LCH₄−STP g VSˉ¹, which yielded the highest biomethane potential than other pre-treatment processes. Subsequently, the third phase was carried out whereby two identical reactors which vary on temperature operation (TR and MR) were used to evaluate the performance of the semi-continuous dry anaerobic digestion of dry grounded (DG) CM. After having a stable condition during the start-up phase, the reactors were fed in semi-continuous mode with different SLR (3, 5, 7 and 9 kg TS/m3·day) for almost 100 days.