Disinfecting the River
Inside the labs at the Calumet Water Reclamation Plant, technicians are closely monitoring treated wastewater before it's released to the Chicago and Calumet River systems.
Currently, sewage from homes and businesses is treated at this, and six other facilities, removing 90 percent of pollutants from the water.
Twenty-four hours a day, millions of gallons of wastewater are pumped through the plant and tested for pollutant content before being released.
Everything from solid material amounts to water pH levels is tracked to determine how efficiently the plant is operating.
“A typical three-step process, every plant or most of them across the country have a primary process. Primary is gravity, anything that sinks, solids are taken off and you have a solids handling process it goes to. That removes about 60 percent of the pollutant and then you have a biological secondary process where you have biological organisms that in natural processes break down pollutants. That brings you to about 90 percent or better removal process for pollutants,” said David St. Pierre, executive director of the Metropolitan Water Reclamation District of Greater Chicago, or MWRD.
After each step in the process, the water gets cleaner and cleaner. But now, the MWRD is preparing to take the process even further.
The agency which manages the region’s waterways and much of Cook County’s wastewater will soon begin building infrastructure to disinfect the wastewater that is pumped back into the Chicago River.
Until last year there was no requirement for the district to disinfect bacteria like fecal coliform out of the water before dumping it back into the river.
“The designation for the Chicago-area waterway station was such that it didn’t require disinfection,” said St. Pierre. “As the district has improved treatment, of course water quality improves and makes the conversation about disinfection possible, and makes the next step of improvement possible.”
The EPA estimates that 70 percent of the water in the Chicago River is made up of the sewage, or so-called effluent.
But disinfection of the wastewater is something that many organizations have been pushing the district to do for decades.
Margaret Frisbie is Executive Director of Friends of the Chicago River.
“The Chicago-area waterways have not been evaluated until this decade. They should have been looked at decades before,” said Frisbie. “So we’re really just behind where we didn’t even ask the Metropolitan Reclamation District who is in charge of our sewage. We never ask them to do this. It doesn’t mean that they couldn’t have taken it in their own planning to do it themselves, but their permits didn’t require it.”
After mounting pressure from the U.S. EPA and environmental activists, the district finally voted last June to add disinfection to its treatment process at its North Side and Calumet reclamation plants, two of the district’s seven wastewater treatment facilities.
“Early in the 2000s, the Illinois EPA did a five-year usability analysis which is triggered by the clean water act,” Frisbie said. “They found that they could make this river attain more use, and so we’re talking about swimming, we’re talking about fishing, we’re talking about people canoeing and kayaking, we’re talking about people motorboating. All of that recreation is a part of these attainable uses. So we need water quality that matches how people are using the river today.”
To reach those goals, MWRD formed an internal task force. For the last few months, they have been exploring technologies and processes that could be used to attain more stringent water quality standards in a cost-effective manner.
Inside the research and development labs at the Stickney Water Reclamation plant in Cicero, feasibility tests are being conducted on some of the potential disinfection methods.
The district is looking at traditional treatments such as chlorination systems.
They are also evaluating newer ozone technologies and have conducted some pilot scale testing of ultraviolet systems as well.
“They have been looking at the different alternatives out there for disinfection,” St. Pierre said. “They’ve catalogued all plants that are above 100 million gallons a day, looking at the different disinfection alternatives that are used. And we have selected really eight different alternatives to look at in detail, price out and see what is the most effective and efficient way to get to the end of disinfection.”
Water District officials say that recommendation is expected to be made by the March 1, when they'll also know more about the actual cost of the project.
Under the current disinfection schedule, officials say selection of technology, final design phase and construction for both the North Side and Calumet Water Reclamation Plants should be completed by December 31, 2015, and be in service for the 2016 recreational season.