STICKNEY PLANT, METROPOLITAN WATER RECLAMATION DISTRICT OF GREATER CHICAGO AREA
Measuring the value of the resource.
Stickney Water Reclamation Plant, part of the Metropolitan Water Reclamation District of Greater Chicago Area (MWRDGC), is the largest capacity waste-water treatment and reclamation plant in the world. We must preface our experience at Stickney by including the high security protocol involved with public entry into such a utility.
Following a written proposal requesting a tour of the plant, we were asked to send a formal tour application and release form along with copies of our state driver licenses to the Public Information Office no less than 30 days prior to our scheduled tour. We were also instructed to bring our IDs with us for entry, and warned that photographs were not permitted. We walked through each of these requirements feeling the weight of the vital resource and MWRDGC’s responsibility to its 5.25 million residents. A serious disruption at the plant could cause great hazard to the water supply being fed back into the Shipping and Sanitary Canal, downstream to the Des Plaines River, and ultimately, into the Mississippi.
We were fortunate to be introduced and led through Stickney by Civil Engineer Peter O’Brien. He was generous with his knowledge, and helped us to understand that the purification process of the Chicago’s waste-water is engineered to be quite similar the natural purification process in a river.
“The Stickney Plant removes pollutants from the waste-water by a series of physical and biological processes. Waste-water enters the plant at either of two locations and is immediately screened to remove large debris. It is then pumped into a chain of processing equipment designed to remove floating material and dissolved/finely dispersed contaminants. The processes include gravity and aerated grit chambers, fine screens, primary settling tanks, aeration tanks, and final settling tanks. About 98% of the pollutants entering the plant with the waste-water are removed by means of the system shown in the Process Flow Diagram. The treatment process is similar to the natural purification process in a river. As the flow progresses downstream in a river, heavy solid material settles to the bottom, and organic material carried in the flow is biodegraded. In the plant, primary treatment involves the physical settling of heavy solid material. In the secondary treatment process a culture of microorganisms consumes the organic material in the waste-water and converts it into cell mass and respiratory byproducts, while some additional organic material adheres to these microorganisms. This cell mass is then separated by gravity in the final settling tank and the clean treated water is discharged to the Sanitary and Ship Canal.” (MWRDGC Stickney Water Reclamation Plant-General Information, April 2007)
Our greater understanding of water reclamation has fueled our appreciation for the advanced technology and engineering that supports this crucial public utility. Our tour of Stickney has also made us realize that it is necessary for us to understand the cycle as a whole by also witnessing the process of water purification and distribution.