The sludge in the secondary sedimentation process, which is relatively diluted, must be thickened prior to treatment.
Secondary sludge thickening is performed with the use of seven gravitational belt thickeners (GBT).
This thickening is performed by adding a polymer (flocculent).
During the thickening process, the concentration of solids increases to about 5% of the sludge.
Sludge thickening belt