The physical character of expanded perlite lends itself to a variety of special purposes—including various applications in the broad category of water quality management. For a detailed explanation of perlite expansion see information sheet: Why Perlite Works
Storm Water Filtration
Due to its high surface area, neutral pH and irregular, porous surface texture, expanded perlite is ideally suited for a variety of applications in storm water filtration; most notably as a component in media filter drain mixes, and another as an element of catch basin filter media.
Roadside Media Filter Drains—Developed by Washington State Dept. of Transportation (WSDOT), media filter drains incorporate horticultural grade perlite, dolomite, and agricultural gypsum held in place by crushed rock, and are placed along roadways to filter suspended solids and other pollutants from roadway runoff.
Catch Basin Filters—Various filtration media—including expanded perlite—are used to remove contaminants from storm water runoff passing through catch basins before being released to local sewer systems and waterways.
Rainwater Surge Reduction & Green Roofs
Horticultural perlite is used as a light weight constituent of soil mixes that make up vegetated roofs. Among the benefits of these roof-top gardens, is the ability to temporarily hold and slow the surge of rainwater encountered during heavy or prolonged rain events. Many municipalities offer credits or other incentives to developers when eco-roofs are incorporated into new building designs. Also see information sheets: Gardens in the Sky and Gently on the Roof.
Soil Stabilization and Liquid Waste Solidification
Tests have shown that the porous structure of fine grades of expanded perlite allows it to absorb up to 8 times its weight in water. This ability underlies its use to stabilize highly saturated soils, water from well drilling services, and other hazardous, liquid wastes. Also see information sheet: Perlite as a Sludge Absorbent.
Perlite’s role in filtration of liquids is well documented (and described in detail elsewhere on perlite.org). It plays an important role in municipal and industrial water treatment systems where it is used in conjunction with a rotary vacuum drum filter to remove solids and other contaminants from polluted waste water.
To download a .pdf of the Perlite for Water Quality Management brochure, click here.
If you have technical questions on this topic, please email the technical contacts listed on our contact page.
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