SBR is another compact way of treating wastewater. It basically breaks down the process into five parts:

Fill Phase

When the wastewater is allowed to fill the tank. This in turn can be done in three different modes:

1. Mixed Fill: When the mixer is on but there is no aeration in the tank. 
2. Aerated Fill: When the mixer and aerator are both switched on. 
3. Anoxic Fill: When neither the mixer, nor aerator are swicthed on. 

React Phase

When the wastewater is allowed to react with the bacteria so that it may biologically degrade.

Settle Phase

When the mixing and aeration is stopped so that the sludge may settle down to the bottom.

Decant Phase

When the clean water on the top is removed without disturbing the sludge that settles on the bottom. 

Idle Phase

When all of the clean water has been drawn off, some of the sludge in the tank is wasted to maintain a required MLSS concentration.