Four final clarifiers (105 ft. x 105 ft.) providing 7.25 hours detention at average daily flow, settle out the Activated Sludge by gravity. A major portion of the activated sludge is returned to the plant flow upstream of the BNR basins. The activated sludge is returned to the plant flow in order to maintain a high concentration of bacteria and microorganisms within the process. The excess portion of activated sludge, known as waste activated sludge, is pumped to a point upstream of the primary clarifiers where it is co-mingled with the raw wastewater and settles with the primary clarifier sludge.

The treated wastewater is disinfected with a 15% chlorine bleach solution in the chlorine contact basins. After chlorination, a sodium bisulfite solution is added to neutralize any residual chlorine in the wastewater before it is discharged to Lake Michigan. The now clean water flows through a 60‑inch diameter concrete outfall pipe that extends 1,570 into Lake Michigan. Detention time in the contact basins is 1.75 hours at average daily flow.