Sources for biogas production cover a wide range of feedstocks
including animal wastes, household wastes, crop residues, sewage
sludge, wastewater and landfill [2]. Therefore, not only wastes can
be disposed of in appropriate ways to help solve the pollution
problems such as foul smell and flies, the process of biogas production
will also provide a cheap and renewable energy source while
conserving fossil resources such as natural gas, oil or coal. Nowadays,
the small biogas production system which refers to the biogas
digester with the size ranging from 12 to 100 m3 has become
popular renewable energy technologies to reduce energy consumption
and emissions in developing countries [3].