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Zelienople, PA — Each Leopold FilterWorx™ tertiary filter is designed and engineered with unsurpassed systems knowledge and applications experience to achieve the specific performance requirements of individual wastewater treatment plants.

Leopold systems knowledge is based on more than 70 years of experience treating wastewater around the world. More than 200 Leopold tertiary filter systems are installed throughout the U.S. and abroad.

Most recently the company completed its largest single tertiary filtration project comprised of a wastewater treatment plant upgrade in Washington, DC. The contract was awarded by the District of Columbia Water & Sewer Authority (DC WASA) for the Blue Plains Advanced Wastewater Treatment Plant and entailed furnishing, installing and placing into successful operation the complete filtration system for the Phase 1 filter upgrade.

Leopold, along with its contracting partners Archer Western Contractors, Ltd. of Sandston, VA; C&E Services Inc. of Washington; Langley Traffic Services, Inc. of Trevose, PA; and Duffield Hauling of King George, VA, began the project in early 2004 and completed it in mid-2007.

The project provided the Blue Plains Advanced Wastewater Treatment Plant with a state-of-the-art filtration system incorporating air-water backwash. Leopold rehabilitated 40 dual bay filters totaling 80 filter cells with each cell measuring 52 ft. x 20 ft. for a total filter area of 83,200 square feet. The plant's average flow capacity exceeds 390 MGD (million gallons per day) with a peak capacity of 850 MGD.

The job included demolition of existing filter equipment; concrete repair; installation of state-of-the-art Universal Type S Underdrain with IMS (Integral Media Support) Cap, media and an air header piping system; removal of existing wash water troughs and replacement with 560 FRP (fiberglass reinforced plastic) troughs plus other miscellaneous items. The filter rehabilitation replaced existing media with 4,333 tons of anthracite from Leopold's Anthracite Processing Facility in Watsontown, Pennsylvania and 4,550 tons of silica sand.

In addition to an extensive underdrain testing protocol, one of the latest tools in filtration design, CFD (Computational Fluid Dynamic) modeling, was employed to verify proper flow characteristics within the filter system prior to the rehabilitation of the filter. The CFD modeling provides precise and exact computer simulation of the filter operation prior to installation of any equipment. CFD modeling was also verified with laboratory scale testing at Leopold's technology advanced Product Development Center.

Leopold tertiary filters employ an upflow water wash with full bed cleaning. To ensure thorough cleaning of the filter media, the filters also employ air scour. Air scour provides very effective cleaning action as the result of higher shear forces in the media bed and abrasion between grains.

Rehabilitated filters can also be custom-engineered by Leopold to add air scour for improved backwash performance. Leopold rehabilitated filters can adapt existing structure to current technology meeting current regulations.

Type S underdrain with attached IMS (Integral Media Support) Cap that takes the place of gravel in the filter media configuration is the latest in a long line of proprietary underdrain technology that Leopold has provided to the filtration industry since 1924.

In addition to the underdrain and IMS Cap, the Leopold manufacturing facility provides all components for a complete tertiary treatment system including the Engineered Filter Media? products, fiberglass products and filter controls. Leopold filter controls are engineered according to plant layout, upstream conditions and effluent permit regulations to not only operate the filter cost-efficiently, but in compliance with stringent regulations. And Leopold takes the initiative for the successful integration of the filter including filter operation and performance to meet each plant's specific requirements.

Also, the Gold Tag Service that accompanies each tertiary filter system means that Leopold stands behind its systems and works in partnership with its customers to ensure smooth filter performance today and in the future. SOURCE: Leopold -- A Xylem Brand