The purification plants consist of the primary treatment container/ balancing reservoir and the SBR reactor. First of all, the sewage flows into the primary treatment container /balancing reservoir where the substance is deposited and forms a sludge deposit on the ground. The sludge must regularly be extracted by suction out of the purification plant. The SBR purification plant functions with the retention operation. The inflowing water is first of all stored in the primary treatment container/ balancing reservoir. Then it is pumped into the SBR reactor where the further treatment of the sewage takes place in five successive phases.

1. Filling:
   

2. The SBR reactor is filled with the sewage of the primary treatment container/ balancing reservoir.

1. Extraction of the excess sludge:
   

2. Since with every new aeration process new activated sludge is produced, the excess sludge is transported back into the primary treatment container/ balancing reservoir in this phase, so that the optimal amount of sludge can be reached in the SBR reactor.

1. Aeration:
   

2. Oxygen is blown into the water through membrane tube aerators. Hereby activated sludge is produced, which consists of germs. In this phase the polluting load of the sewage is biodegraded.

1. Sedimentation:
   

2. During this phase the sewage is not aerated. Through the tranquillisation the activated sludge deposits on the ground of the container. Since the sludge sinks completely to the ground, the clear water remains in the upper area with a perfect water quality.

1. Extraction of the clear water:
   

2. In this phase the clear water is extracted with the help of a clear water pump.