Sequencing batch reactors (SBR) or sequential batch reactors are a type of activated sludge process for the treatment of wastewater. SBR reactors treat wastewater such as sewage or output from anaerobic digesters or mechanical biological treatment facilities in batches. Oxygen is bubbled through the mixture of wastewater and activated sludge to reduce the organic matter. The treated effluent may be suitable for discharge to surface waters or possibly for use on land.


  1. Equalization, primary clarification (in most cases), biological treatment, and secondary clarification can be achieved in a single reactor vessel.
  2. Operating flexibility and control.
  3. Minimal footprint.
  4. Potential capital cost savings by eliminating clarifiers and other equipment.


  1. Municipal sewage treatment plants
  2. Industrial wastewater treatment plants
  3. Used at flow rates of 5 MGD or less.