Blue Header

How it Works

ALCOSAN discharges approximately 140,000 gallons of treated wastewater per minute into the Ohio River.

Sludge Dewatering
A liquid polymer is added to sludge pumped from the mixing tanks to thicken and condition the sludge for drying.  The sludge is then fed into centrifuges which use high speed rotation to separate the moisture content from the sludge, similar to the spin cycle on a washing machine.  The centrifuges process approximately 44,000 dry tons of sludge per year with an average solids percentage of 28-33%.

Energy Recovery Facility
Approximately 32% of the sludge dried by the centrifuges is incinerated in ALCOSAN's two fluidized-bed incinerators.  Super-heated air is added to a 5' bed of fluidized sand burning at 1500 degrees fahrenheit.  Sludge is mixed into the sand where it is instantly incinerated.  The hot "off-gas" from the incineration process is carried out and is reused to heat boiler feet water, to create steam for plant use and to generate electricity.

Odor Control
Process odors are controlled at three points through the use of packed tower scrubbers, in which foul air is captured and chemically "scrubbed" prior to its release into the atmosphere.  These scrubbers use both sodium hypochlorite and caustic soda to treat odors at the plant headworks, primary sedimentation and dewatering.


1 2 3 4
















Contact   |   News   |   Events   |   Consent Decree   |   Careers   |   Sitemap

All content © Copyright Allegheny County Sanitary Authority

3300 Preble Avenue
Pittsburgh, PA 15233
(412) 766-4810