Gabriel Environment Blog

MWRD’s disinfection project to make the Chicago River safer for recreation

March 30th, 2016
Ribbon Cutting at the MWRD O'Brien Water Reclamation Plant in Skokie, IL on March 23, 2015

Ribbon Cutting at the MWRD O’Brien Water Reclamation Plant in Skokie, IL on March 23, 2015


Metropolitan Water Reclamation District (MWRD) officially brought their disinfection project at the O’Brien Water Reclamation Plant online last week.  After nearly a decade of legal battles fighting federal regulations, MWRD agreed in 2011 to install UV equipment to neutralize microbes in the water before it’s released into the North Shore Channel.

Last year, levels of fecal coliform bacteria in the wastewater discharged from this plant averaged 8,449 colony forming units (CFUs) and spiked as high as 210,000 CFUs last year. Illinois’ standard for recreational waterways that are ‘fishable and swimmable’ is 200 CFUs.  The disinfection process won’t reduce the CFUs to a low enough level to make the river safe for fishing or swimming, but will dramatically reduce the health risks for kayakers, canoers, and others who use the Chicago River recreationally.  Fecal coliform bacteria can cause diarrhea, nausea, eye infections and skin rashes if ingested or enter the body through open cuts.

The O’Brien WRP now includes a third treatment stage to its wastewater process:

  1. Primary treatment – screens, settling tanks and other physical processes
  2. Secondary treatment – biological and physical processes
  3. Disinfection treatment – seven channels with 896 powerful UV light bulbs

This plant has the capacity to treat over 450 million gallons per day.

An earlier blog post highlighted a WBEZ ‘Curious City’ story about Chicago’s wastewater treatment process which gives more details about the primary and secondary treatments listed above.

“It’s great this is finally happening,” said Ann Alexander, a senior attorney for the nonprofit Natural Resources Defense Council, one of the groups that pushed for years to start treating the Chicago River like other U.S. waterways. “But there is a whole lot of work still to be done to make the river as safe and pleasant as we know it can be someday.”

More photos and a video from the disinfection program’s ribbon cutting ceremony can be found on MWRD’s Facebook page.

Source:  “Chicago River cleanup makes water safer for recreation,” March 21, 2016, Chicago Tribune.

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