The Metropolitan Water Reclamation District of Greater Chicago (MWRD) – of which the Terrence J. O’Brien Water Reclamation Plant (WRP) is part of – has made a number of upgrades to its treatment process in recent years. The addition of UV disinfection has been a critical part of these upgrades; it played a key role in improving water quality throughout the Chicago Area Waterway System (CAWS).

The Terrence J. O’Brien WRP (originally called North Side) was built to serve residents in communities north of downtown Chicago. In operation since 1928, it originally treated sewage for a population of 800,000 within a 78-square-mile area, but now both the service area and the population are nearly twice as large. The plant now serves over 1.3 million people in an area of 143 square miles and treats an average of 230 MGD of wastewater.

A Need For Innovation

The need for change was recognized by the MWRD Board of Commissioners in 2011 when new regulations required the facility to add a disinfection process to their wastewater treatment system. With the goal of re-classifying the CAWS to allow primary contact, they set out to research the most economical and optimal disinfection technology for the facility.

After investigating various disinfection approaches and technologies, officials determined that UV was the optimal solution for the plant and application.

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