o Objective:  Asses the feasibility of achieving the disinfection requirement of the primary effluent overflow during wet weather events through the existing Rouge River Outfall (RRO) o Methodology:  High rate disinfection approach Application of high-rate mixing (G value between 500 and 1,000 s -1 ) in combination with a chemical disinfectant Contact/detention time of less than 15 minutes  Flow rerouting schemes during wet weather events  Evaluate disinfection alternatives use a Triple Bottom Line (TBL) approach Peracetic Acid (PAA) Ultraviolet Irradiation (UV) Bromine based Guanidine based Chlorine/Sodium Hypochlorite Existing Flow SchemeProposed Flow Scheme Balancing Environmental Stewardship and Cost in the Disinfection of Wet Weather Flows in Water Resource Recovery Facilities Isaiah Shapiro, EIT  Dimitri Katehis PhD, PE  Lin Liang, PE Overview Methodology Bench Scale Testing Recommendation o Detroit Sewerage and Water Department (DWSD) o Largest single-site wastewater treatment facility  Primary Capacity = 1,800 MGD  Secondary Capacity = 1,100 to 1,400 MGD  Primary Overflow during Wet Weather: 400 to 700 MGD o Largest single-site wastewater treatment facility o Permit requirement for both secondary effluent and primary effluent overflow:  Fecal Coliform 7-day: 400 cfu/100 mL  Fecal Coliform 7-day: 200 cfu/100 mL o Proposed Rouge River Outfall 2 (RRO-2) to provided 30 minutes of contact time. o Based on the Triple Bottom Line (TBL) evaluation concluded that chlorination is the most viable option o Hence, bench scale was conducted to validate the disfection efficiency at a contact time of less than 15 minutes for both secondary effluent and primary effluent under wet weather conditions o Three scenarios were considered at vary level of chlorine dose:  Chlorination of Primary Effluent  Chlorination of Chemically Enhance Primary Treatment (CEPT)  Chlorination of Secondary Effluent Results Primary EffluentChemically Enhanced Primary TreatmentSecondary Effluent Findings Existing Flow Scheme Proposed Flow Scheme o Primary Effluent :  Bench testing results show that the target f. coli level was not achieved at chlorine doses of 5 or 10 mg/L even at a contact time of 30 minutes. Although, adequate disinfection can be achieved within minutes at the highest chlorine dose applied of 20 mg/L. o Chemically Enhance Primary Treatment:  Test results indicate that the f. coli target level can be achieved at between 2 and 15 minutes depending on the chlorine dose. At doses of 10 mg/L and greater, less than 10 minutes of contact time are adequate to meet disinfection targets. o Secondary Effluent:  Results show that adequate disinfection of secondary effluent occurs between 2 and 10 minutes depending on the chlorine dose. At a dose of 5 mg/L up to 10 minutes of contact time is required to achieve the disinfection target; however at doses of 10 and 20 mg/L, less than 5 minutes of contact time is required. Table: Results of the bench testing in terms of contact time required to achieve a f. coli count of 200 MPN/100 mL for a given chlorine dose Outcome o Based bench scale results and hydraulic modeling analysis, this study concluded that high rate disinfection with chlorine in conjunction with the proposed flow rerouting scheme during wet weather conditions is a viable alternative to the construction of the Rouge River Outfall 2 (RRO-2). o This approach was recommended to the Detroit Sewerage and Water Department (DWSD) o Michigan Department of Environmental Quality (MDEQ) has approved disinfection of the secondary effluent through the existing RRO and the excess primary effluent through DRO during wet weather events. o Averted $70-90 million capital project to construct RRO-2 o Estimated capital cost to allow for the flow modifications is $10-15 million Acknowledgments: Dan Schechter – DWSD Nicole Spieles – Greeley and Hansen Jared Buzo – Greeley and Hansen