Reuse of Treated Wastewater in Metro Chicago

Abstract

The Metropolitan Water Reclamation District of Greater Chicago (District) operates seven wastewater treatment plants that, in 1989, treated 1.8 × 1012 | (4.8 × 1011 gal) of wastewater. Some of the wastewater that is treated is reused, either externally by outside sources or internally within the plants, as an alternative to using potable water. The exported plant effluent is used for purposes of irrigation and commercial plant processes. The plant effluent that is utilized internally is used for equipment washdown, irrigation, pump seal water and wear ring flush, filter backwash, aeration tank foam control, equipment cooling water, venturi pressure tap purge, pipe flush, polymer solution make-up, sludge thickener dilution, and odor control. There are some problems associated with the reuse, but the underlying basis for using plant effluent rather than potable water is cost. It is less expensive to use plant effluent and, as long as the treated wastewater does not cause harm or damage, plant effluent is used.