MINIMIZING MIXING ENERGY IN ACTIVATED SLUDGE SELECTOR BASINS - A MIXING ENERGY PILOT STUDY

摘要

With the goal to minimize energy consumption in the biological nutrient removal (BNR) process, a mixing energy pilot study was conducted at Milwaukee MSD's South Shore Water Reclamation Facility in Oak Creek, Wisconsin. Results show that power consumption of only 0.28 W/m3 is sufficient to fully homogenize activated sludge using a submersible horizontal low-speed adjustable-thrust propeller mixer, (SHLSATP mixer). The study concludes that the SHLSATP mixer, compared to other mixing methods, consumed the least amount of energy by far, while still providing good mixing and treatment. These results lend support to the statement that "Limited published data suggests that power levels much below the traditional design criteria (as low as 0.1 - 0.2 W/m3 or 0.5 - 1.0 hp/mil gal) are able to maintain adequate mixing, as indicated by the variation of mixed liquor concentration vertically in an activated sludge tank." (Paper presented at WEFTEC 2015, "How Oversized Mixers Became an Industry Standard")