Up-flow anaerobic sludge blanket technology also known as UASB reactor is a form of anaerobic digester which is used in wastewater treatment. UASB reactor is a methane-producing digester, which uses an anaerobic process and forming a blanket of granular sludge and is processed by the anaerobic microorganisms. It is a single tank process where wastewater enters the reactor from the bottom and flows upward. A suspended sludge blanket filters and treats the wastewater as the wastewater flows through it. At the same time, biogas is formed in the reactor, which is collected from the top.
Typically this technology is used for wastewater having a low level of solids. Industrial wastewater, as well as sewage, can be treated with UASB technology to reduce COD/BOD by 70-90%.