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RESPONSIVE DESIGN ACHIEVES WATER QUALITY THRESHOLDS
Author: Timothy J. Block
Date: 10/04
2004 WEBTEC Technical Sessions

Ely is a city of approximately 4,000 people, and is located in northeastern Minnesota. It is also recognized as the taking-off point for the Boundary Waters Canoe Area Wilderness (BWCAW). Ely has long been highly regarded as a recreational area for citizens throughout the nation, with beautiful lakes and excellent fishing. Consequently, Ely citizens are keenly aware of the importance of protecting these natural resources. The 3-mgd Ely WWTP discharges into 2500-acre Shagawa Lake, a culturally eutrophied lake in an area of oligotrophic lakes. The nutrient levels and algal blooms in highly-visible Shagawa Lake are important because the next lake downstream marks the beginning of the BWCAW. Thus, NPDES effluent permit requirements at the Ely WWTP are amongst the most stringent in the nation, and include a 0.3 mg/l phosphorus limit. This paper demonstrates that a biological selector is viable for phosphorus removal in extremely cold climates. This paper also demonstrates that the biological phosphorus removal system, coupled with the multi-media filters, is an effective technology for meeting effluent phosphorus limits of 0.3 mg/l. In addition, this project may also serve as a model for other small communities that are faced with financing significant capital programs for wastewater collection and treatment, as well as the importance of securing appropriate locally-based support for such a program.

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