The special porous structure of Filtralite® Pure filter media makes it possible for water to pass through the filter bed in the best possible way, improving the filter’s capacity to hold onto impurities. By increasing the contact area, this feature, which is intrinsic to the lightweight expanded clay material, enables higher quantities of water to be filtered through the same space.
Therefore, by converting from traditional filtering media to Filtralite® materials, water management facilities can increase their production without having to rebuild or enlarge existing structures.
Background & Challenge
The Fredrikstad Drinking Water Treatment Plant in southeastern Norway, serving Fredrikstad and Hvaler municipalities with an annual water output of 15 million m³, underwent a critical filtration upgrade due to the deterioration of its sand/anthracite filter media over time.
Pilot Phase & Expansion
In March 2002, one of the eight dual-media filters was retrofitted: the anthracite layer was replaced by Filtralite® media, tested atop the existing sand layer. This pilot filter operated alongside the remaining conventional filters for nearly a year.Impressed by the results, the utility opted to expand the installation to all filters. Over a rehabilitation period, each filter was individually taken offline for cleanup, sand replacement, and installation of 0.6 m of sand (0.8–1.2 mm) plus 0.8 m of Filtralite® MC (1.5–2.5 mm)—taking approximately one week per filter to complete, all while maintaining full plant operation.
Performance Improvements
Post-refurbishment, the filters maintained excellent water quality and demonstrated longer run times compared to traditional media operation. The plant handles raw water from Lake Isnesfjorden—linked to Norway’s largest river, Glomma—which exhibits variable turbidity (up to 10 NTU) and color (as high as 100 mg Pt/L) under challenging conditions. Treated water exiting the dual-media filters achieved as low as 0.06 NTU turbidity, down from an inlet average of 1.1 NTU, with a standard filter velocity of 10 m/h.
Changing from sand/anthracite filters to sand/Filtralite® filters resulted in longer run times and good water quality.
Mohammed Kastawy
Area Sales Manager – MENA Region
Mobile: +971565503535
Email : mohammed.kastawy@saint-gobain.com
LinkedIn: www.linkedin.com
