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Minimizing mixing energy in activated sludge selector basins.
How Low Can You Go?
Milwaukee MSD South Shore WWTP – Mixing Pilot Study
With the goal to minimize energy consumption in the BNR process, a mixing energy pilot study is under way at MMSD in Milwaukee, WI. Results show that power consumption of only 0.28 W/m3 is sufficient to fully homogenize activated sludge. This record-setting low energy mixing is achieved using a high-efficiency adjustable-thrust submersible mixer with optimum position in a BNR selector zone. The zone dimensions are 48 ft long x 30 ft wide x 15 ft deep. TSS profiles, phosphorous removal and power measurements were studied as mixing energy in the selector basin was gradually reduced over time.
The study concludes that the best of 3 mixing systems achieved both successful mixing and nutrient removal at 0.28 W/ m3. One key to success is a submersible mixer with adjustable-thrust, low-speed, large diameter propeller whose thrust can be fine-tuned to the basin shape. The other key is positioning the mixer to produce an efficient bulk flow loop that takes advantage of the basin shape .
This session will be presented by Jim Fischer , Senior Applications Engineer, Mixing at Xylem.
Senior Applications Engineer, Mixing
Jim is a senior applications engineer and mixing expert at Flygt. He’s a graduate of Marquette University and helped create Flygt’s “Handbook of Mixing for Wastewater and Similar Applications. He’s a licensed professional engineer in Wisconsin and holds a patent for a vortex suppressor to protect mixers from the harmful effects of air intake.