| In answer to the stringent Federal Surface Water Treatment Rules now in effect, Rosedale has developed a filter bag
certified to remove the giardia lamblia cyst. Giardia is the main cause of camper’s diarrhea and other digestive illnesses.
The rule regarding giardia is that 99.9%
(3 log) must be removed (2 log through filtration and 1 log through disinfection). The Rosedale Giardia Lamblia Removal (GLR) bag is certified to be 99.95% efficient at 3 microns.
The relative low cost of these bags makes them the ideal solution for smaller water authorities. A single-bag filter housing with a GLR bag can filter up to 20 gallons of water per minute. Using Rosedale’s multi-bag filter
housings, it is possible to filter water at up to 500 GPM. These housings can be banked together in parallel, providing even greater throughput. A pre-filter must be installed prior to the GLR
housing to filter out larger particles, lessening the dirt-load on the GLR bag (see page 133). The GLR bags are made of various layers of polyester or polypropylene microfibers and standard fibers variably calendered to obtain the ratings as shown. This greatly increases the dirt-holding capabilities of these bags.
These bags have as many as 26 layers
of high-efficiency microfiber material
for filtering out contaminant. The initial layers are pre-giardia filtration levels. The next 3 layers are barriers that prevent any of the bag material from migrating into the effluent.
All GLR bags have a machined polypropylene top that has a sealing gasket. All seams and joints on the bag, including the top, are sonically welded to prevent leakage.
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