Detroit Wastewater Treatment Plant Disinfection at the Rouge and Detroit River Outfalls

Location: Detroit, MI

Client: Detroit Water and Sewerage Department

Detroit Wastewater TreatmentCCJM was prime consultant to Detroit Water and Sewer Department (DWSD) on this project which consists of study, design, and construction phase office services for a new chlorination facility.

With a feed capacity of 121,000 ppd, it is believed to be the largest chlorination system in the United States. CCJM also was prime consultant on related projects for a new dechlorination facility and a new outfall tunnel.

The study phase consisted of an evaluation of the means, methods, and systems to provide adequate disinfection capacity from a new chlorination facility for 840 mgd of secondary effluent and up to 1000 mgd of primary treated wet weather flow prior to discharge to the Detroit River. Bench scale and pilot scale (100 GPM) studies were conducted to obtain design parameters for disinfection and biotoxicity of disinfected effluent. Bench scale studies results were used to design pilot-scale tests. Both acute and chronic aquatic toxicity data were obtained using ceriopahnia and minnows. To simulate wet weather flow conditions, flow to one of the primary settling tanks was varied and its effluent was used during the bypass flow disinfection study. Design parameters for chlorine and sulfur dioxide doses, mixing times and contact time were established.

The existing outfall has insufficient capacity to handle the proposed wet weather flows, so a second outfall was proposed. The new 21’ diameter outfall tunnel will serve as a back-up outfall during dry weather conditions, and will provide contact time for chlorination and dechlorination.

The chlorination facility houses railroad tank cars, chlorination equipment and ancillary equipment. The building has the capacity to house six 90-ton railroad cars. The chlorination system consists of 16 trains of evaporators, chlorinators and injectors, each with a 10,000 ppd capacity.  A 5,000 gpm booster pump station supplies city water to the injectors. Separate chlorine gas scrubber ventilation equipment provides a negative interior building pressure to prevent accidental release of chlorine to the atmosphere.