UASB (Upflow anaerobic sludge blanket) maintains a high concentration of biomass through the formation of highly settleable microbial sludge aggregates.

The waste water flow upwards through a layer of active sludge to cause anaerobic digestion of organics of the waste water.

The process is suitable for soluble waste water as well as waste waters containing particulate matter.

The waste water enters the tank from the bottom and flows upward through the sludge bed, which gets formed during the process itself. The sludge bed develops microorganisms capable of flourishing an O2 deficient environment.

The sludge bed traps the suspended organics of the up moving waste water. The suspended solids trapped in the sludge bed are degraded by the anaerobic and the anaerobically working bacteria, producing CH4 and CO2.

The biogas is collected at the top of the tank in a gas collector, from where it can be withdrawn for use as a byproduct while the water sludge mixture is made to enter a settling tank where the sludge settles down and flows back into the bottom of reactor.

The sludge will show good settling properties after an initial start up period, followed by granulation, forming a sludge blanket or sludge bed in the lower part of the reactor.