SBR is an activated sludge process designed to operate as a batch process instead of a continuous process. Here aeration and sludge settlement occur in the same tank. The SBR design is a fill-and-draw type activated sludge process where the following steps take place consecutively i.e. anoxic fill, reaction, settling, decanting followed by sludge wastage. The SBR aeration system generally consists of fine bubble air diffusers. In this process, the compressed air is sheared in to small bubbles creating large specific surface area for high mass transfer efficiency between air and wastewater. SBRs produce sludge with moderate settling properties provided the influent wastewater is admitted in to the aeration in a controlled manner. The SBR process is fully automated to control the operation of the various cells.

Filling, aeration and settling is done by PLC based timer operation. The settled effluent is decanted using a decanter mechanism. Sludge is withdrawn and recycled to the tank inlet for maintaining required MLSS and anoxic conditions. Excess sludge is dewatered in a thickener followed by filter press and then disposed.