The nitrification mixed liquor then flows to the four Nitrification Settling Tanks for liquid/solid separation, much like the MA Aeration system. The sludge that is collected in the settling tanks is returned to the head of the Nitrification Aeration Tanks. A portion of this sludge is “wasted” to the Gravity Thickeners for final process and disposal (thickened, dewatered, incinerated, and disposed of as ash at an approved sanitary landfill).

The treated wastewater flow overflows the weirs to the next process which is filtration.