“Big Disinfection” in Chicago: the Fast-Track Design of 480-mgd Disinfection Facilities for the Calumet Water Reclamation Plant

The Metropolitan Water Reclamation District of Greater Chicago (MWRD) is implementing disinfection at the Calumet Water Reclamation Plant (WRP), which treats peak flowrates up to 1,817 million liters per day (MLD), or 480 million gallons per day (mgd). For the 2016 disinfection season, MWRD will begin disinfecting Calumet WRP effluent before discharge to the Chicago Area Waterway System (CAWS).The new disinfection facilities will consist of sodium hypochlorite for chlorination, providing disinfection, and sodium bisulfite for dechlorination. The Calumet WRP's existing chlorine contact basin (CCB) will be modified and used to provide chlorine contact time for disinfection of the plant's secondary effluent, and dechlorination will be accomplished as flow exits the CCB.The disinfection facilities at the Calumet WRP will be among the largest in North America. Key elements of the project include its fast-track schedule, bench-scale testing program, and innovative design features incorporated for a facility of this size.