Sequencing Batch Reactor
The Sequencing-Batch-Reactor process (SBR process for short) is a variant of the conventional activated sludge process . The SBR consists of a reaction space which first takes on the function of a biological reactor and then that of a sedimentation basin . In contrast to reactors with continuous flow, the SBR is filled and emptied discontinuously . The traditional spatial separation of biological processes and sedimentation is replaced by a temporal one. The time interval from the beginning of the filling process to the end of the clear water extraction and a possible rest phase is called a cycle . At least two independent tanks are required for the SBR process. These each go through a cycle that can differ from sewage treatment plant to sewage treatment plant. A simple cycle consists of the phases filling- mixing- filling- aerating- sedimentation- decanting. In the sedimentation the sludge settles at the bottom. In the decanting area, a telescopic slide moves down to remove the clear water layer. This process is often used in industrial sewage treatment plants.
The SBR cycle is characterized by a sequential process phase sequence. The hydraulic decoupling of the SBR process makes it possible to vary the duration, frequency and arrangement of the phases of the cycle. The cycle begins with the filling phase, in which the first degradation processes begin under anaerobic or anoxic conditions. In the actual degradation or reaction phase, the reactor is ventilated. Depending on the cleaning goal, unventilated phases can also be introduced. This is followed by the sedimentation phase in which the activated sludge settles and a clear water layer is formed. In the decanting phase , the excess clear water is drawn off. This can be followed by an operational rest phase or the cycle starts again. A separate clarification is not necessary for the SBR procedure.
An example of an SBR plant in Sollenau , Wr. Neustadt in Lower Austria :
- Expansion size: 60,000 PE ( population equivalent )
- Max. Intake: 12,000 m³ / day
- Efficiency related to COD ( chemical oxygen demand ) (2005): 94.5%
- Efficiency related to the BOD ( biochemical oxygen demand ) (2005): 97.9%
- 4 pools of 7988 m³ each
- Sludge accumulation ~ 3000 t / year with ~ 23% dry matter content
Even small sewage treatment plants will be built with the SBR technology since the year 2000. Since then, this technology has developed into the best-selling small wastewater treatment system. Today, the same drainage qualities are achieved as in municipal sewage treatment plants.