SBR technology (Sequencing Batch Reactor) is a variant of the conventional activated sludge wastewater plant: oxidation and sedimentation stages take place in time sequences within the same tank.
Once filling/oxidation/nitrification of sewage is completed, eventually even in alternation with denitrification, aeration unit is stopped (together with the feeding unit) and sludge starts to precipitate (settling) within the tank.
After a preset time, clarified water (treated liquid) is removed by an electric pump (or by gravity) and sent to the outlet, or conveyed to further process stages (tertiary treatments).
The advantages of this system, beside its simplicity related to the use of a single tank for aeration and sedimentation, are the possibility to equalize influent sewage and to prevent the formation of floating layer of scum (as they are continuously removed by reactivation of the oxidation stage).
For these reasons, the system is often used in the treatment of industrial wastewater with discontinuous charge, on both qualitative and quantitative levels, or in prefabricated plants for small communities.
It can be used also on civil plants where, due to the continuous hydraulic charge, is usually realized through a double line with alternate operation.