Chicago RiverThe O’Brien Water Reclamation Plant serves over 1 million people within a 143 square mile radius. The plant has recently added a final stage of ultraviolet (UV) disinfection in an attempt to transform the Chicago river, making it the world’s biggest ultraviolet (UV) disinfection facility.

The Chicago river is known for being severely polluted. However, it’s about to become a lot cleaner with disinfection technology at the Skokie water treatment facility.

Ultraviolet radiation will execute all harmful pathogens and bacteria within the water before it is released from the O’Brien plant into the North Shore Channel and North Branch of the Chicago river.

The O’Brien Water Reclamation Plant

The O’Brien Water Reclamation Plant has the room to treat around 450 million gallons of water each day and serves over 1.3 million people within the 143 mile radius.

The water reclamation plant will have 896 ultraviolet lamps shine on the treated water, turning it a green colour that is reminiscent of the yearly dyeing of the Chicago river. However, this isn’t caused by green dye, it is caused by germ killing ultraviolet rays.

The O’Brien plant is the second of the Metropolitan Water Reclamation District’s (MWRD) to disinfect treated water. In 2015, it's Calumet facility started disinfecting treated water - using chlorine killing bacteria - discharged into the Calumet river system. However, as the chlorine is damaging to the environment, a de-chlorination process is essential once the process has taken place - making it less effective than UV disinfection.

The Ultraviolet Disinfection Approach

Not only is the O’Brien plant’s approach cheaper than using chlorine, it is also safer for the environment. UV disinfection ensures there are no dissolved solids or possible disinfection by-products in the water.

The Water Reclamation plant extracts sludge and solids from industrial and human waste in the water before the microbial processes break down the organic matter. However, it wasn’t until now that it disinfected treated water as the last step.

Lowering Health Problems

The new disinfection process will lower the risk of health problems resulting from direct contact with the water whilst swimming or recreational activities in the waterway. However, the river is not clean enough for swimming just yet.

Chicago RiverThe City’s Sanitation Problem

A section of the city’s sanitation problem is due to the antiquated combined sewer system that continually unleashes stormwater and raw sewage into the river after heavy rainstorms cause overflows. Water treatment plants aren’t able to manage the excess wastewater, so it can be safely released into the waterways.

MWRD is hoping the McCook Reservoir will be an element of Chicago’s large-scale Deep Tunnel Project, which will help ease this problem. After heavy rainfalls, the reservoir will acquire the excess sewage from the O’Brien plant to be treated at a later date.


Belmar Technologies design, build, install, commission and service complete industrial wastewater treatment systems for a wide range of sectors. For more information or to discuss our services further, please feel free to get in touch either by email to mail@belmartechnologies.co.uk or by calling +44 (0) 1327 586 008.