From entrance into the Pumping Station to discharge in the Monongahela River, sewage takes approximately 12 hours to pass through the Authority's treatment plant. First, sewage is lifted into the Screen and Grit Building [See Fig.1]. Then, it flows underground to the C&I Building and on to the primary settling tanks [See Fig.2]. Screw pumps lift sewage flowing from these tanks into aeration tanks. There it is treated with activated sludge.

After about 6 hours in the aeration tanks, the flow enters the final clarifiers [See Fig.3]. The sludge settled in the clarifiers is either returned to the aeration tanks, or put with primary sludge on the Belt Press [See Fig.5] then sent to a landfill.

The treated sewage from the clarifier is sent through the contact tanks [See Fig.4], where it is chlorinated before final discharge into the Monongahela River.

The transition from coarse bubble aeration to fine bubble aeration began in 1998. This change is both cost and energy efficient and will help meet the area's treatment needs well into the future.

	[FIGURE 1] Rags, sticks and residue are removed from the sewage flow before passing through to the C&I Building where flow is metered and slowed.
[FIGURE 2]  Flow is slowed and allowed to settle. Heavier sludge sinks to the bottom and is removed. Floating debris is removed from the surface of the sewage.
	[FIGURE 3]  Activated sludge settles on the bottom of the final clarifiers and is recirculated back to the aeration tanks or removed to the belt press. Clean, treated water on top goes to the contact tanks.
[FIGURE 4] Treated sewage is chlorinated as it enters the contact tanks in the final step, killing most of the remaining bacteria before the water is discharged
	[FIGURE 5] The belt press dewaters the sludge into a "cake" that is then hauled to an approved landfill.