Advanced Secondary Settling

After the wastewater has been through advanced secondary treatment, the waste-stream is once again full of organic material from the bacteria that has sloughed from the two biotowers. At this stage, the remaining solid material is in very small particles, which do not settle as easily as large clumps of material would.

Process Time
For this reason, the capacity of the advanced secondary settling tanks is more than the volume of the primary and secondary settling tanks together. This allows the wastewater the maximum amount of time to slow down and allow the solids to settle out.