119
5.2.2.13 Rotating Biological Contactor
A rotating biological contactor process contains series of closely spaced, parallel
discs on a rotating shaft that is partially submerged in wastewater tank where steady
flow is maintained. Microorganisms grown on the discs will absorb pollutants and
peels off, which are removed in secondary clarifier (or sedimentation tank).
5.2.2.14 Sequential Batch Reactor
Sequencing batch reactor (SBR) process has been used widely over the past few
decades due to its cost-effectiveness and simplicity for treatment of domestic and
industrial wastewater (Ghazani and Taghdisian 2019).
Sequential batch reactors (SBRs) contain a single tank where in treatment is
done by repetitive cycles of aeration and sedimentation. The cycle in SBR is shown
in Fig. 5.10.
The fill operation is followed by a react operation where the microorganisms
react on organic matter in the wastewater. The biological flocs formed in the reaction phase are separated during a settling operation, and clear water is let out. During
the idle period, excessive settled sludge is removed from tank.
Fig. 5.9 Aeration tank with surface aerator
5.2 Engineering Control