The UASB reactor is a form of an anaerobic digester that is used in the wastewater treatment process. It is a methane-producing digester that uses an anaerobic process and forms a granular sludge processed by anaerobic microorganisms. UASB reactor is a single tank process used in a centralized or decentralized anaerobic industrial wastewater treatment that seeks to achieve the removal of a high rated volume of organic pollutants. It has been recognized as one of the most important technologies in the anaerobic treatment process.