Biogas production from various coal types using beef cattle rumen’s liquid as a source of microorganisms consortium

Nowadays, Indonesia is developing Coal-Bed Methane (CBM) production, but its production is not sufficient yet. Basically, CBM is produced naturally along with coal formation, i.e. through the activity of indigenous microorganisms. In this regard, to increase the production of CBM, adding a consortium of microorganisms into the coal deposit can be an option. One source of a consortium of bacteria available in nature is the rumen contents of ruminant livestock such as beef cattle. The purpose of this research was to know the capability of bacteria in rumen contents of beef cattle to produce CBM from various types of coal. In addition, to get a better concentration of bacteria than previous research so that it can be used as a reference for CBM production in the future. This explorative research used an experimental method with descriptive explanation. CBM production was performed using Hungate tube as a digester with three coal substrates, namely lignite, sub-bituminous and bituminous. This experiment also used 10−7 diluted rumen content of beef cattle as a source. The parameters measured were bacterial density, the amount of CBM, carbon dioxide and nitrous oxide on day 2, 5, 10 and 14. The treatment and parameters measurement were carried out in triplicates. This study finding showed that the highest bacterial density in all three types of coal was obtained on day 10 as well as the amount of CBM, carbon dioxide and nitrous oxide. These results are higher than the results from previous research therefore, this treatment can be used as an inoculant in a solid form for easy distribution.