New Wastewater Ultraviolet Disinfection System for Terrence J. O’Brien Water Reclamation Plant

When the Metropolitan Water Reclamation District of Greater Chicago (District) sought to safeguard and enhance water quality discharging from the Terrence J. O'Brien Water Reclamation Plant (WRP) using ultraviolet (UV) disinfection technologies, the District engaged Greeley and Hansen to design and oversee construction of the world’s largest wastewater UV disinfection system by flow.  

Preliminary design of the $61.7 million O'Brien WRP UV disinfection system was completed within seven weeks, comprehensive design was completed within one year, and construction was largely completed while the plant remained in operation. The innovative and power efficient seven-channel UV design eliminated $20 million in capital costs, and significantly reduced ongoing power generation requirements and system maintenance costs. 

A cutting-edge application of UV disinfection technology to the plant’s wastewater treatment process, the system features 896 high-output/low-pressure UV lamps that enable a high-capacity treatment volume while reducing energy consumption and operating costs. The unique UV disinfection system configuration enables independently operable UV channels to be activated or deactivated on demand to accommodate large variations in flow ranging from 230 MGD to 450 MGD, and permits easy lamp replacement and system maintenance while the system remains operational.  

Innovative planning and design, operational collaboration, and disciplined construction management enabled meeting multiple goals within budget and on schedule. Meeting and exceeding all MWRD requirements, the success of the O'Brien Plant UV System project enabled the District to fulfill commitments to the EPA, environmental groups, and community stakeholders for improved public safety and cleaner waterways for Chicago-area citizens. 

Project Highlights: 

• Recognized with Engineering Excellence Honor Award by the American Council of Engineers of Illinois.
• Largest wastewater UV disinfection system by flow.
• Design included low-lift pumping station and effluent filtration facilities.
• Power reliability, electrical and control systems engineering to support new UV disinfection.
• Delivered on expedited schedule.