Sequencing Batch Reactor (SBR) Technology II

1. STEP 4: Decant
   The treated clarified liquid is discharged or decanted using pumps which have their intake located at the midpoint of the Reactor depth. This assures that any floating debris or settled biomass is not discharged from the Reactor. A non-return valve on the pump intake prevents the entry of solids into the Decant pump and piping during the aerated treatment steps.
2. STEP 5: Idle
   When the Reactor has decanted, and there is no wastewater waiting to be pumped to the Reactor, the Reactor enters an idle, or waiting phase. In idle, with no wastewater load, it is not necessary to run the blowers at the same rate as during the filling stage. The blowers automatically reduce the volume of air at idle, saving energy. When the Reactor receives more wastewater, it automatically switches back to the FILUREACT step, and the entire cycle repeats.

Sludge Waste
Since the biomass continues to grow or increase in volume during each treatment cycle it is necessary to remove excess biomass from the Reactor on a regular basis. The biomass volume is always maintained below the pump intake and at the "proper level by means of automatic sludge waste pumps. The excess biomass is pumped to the Trash Tank at the head end of the plant where it is anaerobically (without air) decomposed. Regular sludge wasting ensures that enough biomass remains in the Reactor to treat the next batch of wastewater, but does not increase to the point where it would be pumped out of the Reactor during the Decant cycle.