Due to a high surface area, neutral pH, irregular, porous surface texture, and variety of grades, expanded perlite is ideally suited for a variety of filtration applications. On the the fine-grade side, expanded perlite serves as a finely-tuned filter aid in pressure or vacuum filtration equipment. Larger grades of perlite are key media components in storm water control and filtration systems.
Perlite as a Filter Aid
Perlite filter aids are widely used in industries tasked with the separation of liquids and solids—even gases and solids. Due to low density, availability, performance, economy and environmental footprint, perlite filter aids are used for treating water and wastewater, food processing, industrial oil and solvent recovery, extractive metallurgy, and for purifying chemicals, resins, polymers, waxes, oils, gums, paints and more.
Expanded perlite can be milled and classified to meet specific flow characteristics. When the foam-like perlite bubbles are crushed, the result is a jagged interlocking structure with billions of microscopic channels and an aggressive filtration profile. Perlite filter aids are lightweight, sterile and inert, impart no taste, color or odor to filtered liquids.
The value of a filter aid is the protection it provides to the filtering surfaces, preventing blockage. A perlite filter aid provides a filtration layer, or cake, that transfers the filtration from the septum to the entire mass of the filter aid. Unwanted solids are trapped in the filter aid cake and, at the end of the filtration cycle, easily release from the septum, facilitating clean up and increasing productivity.
Perlite filter aids are usable with standard filtration equipment and generally replace other filter aids on a one-to-one volume basis. Perlite filter aids also provide a density advantage from 20 to 50-percent over other types of filter aids—in other words, larger filtration volumes with lower bulk densities.
Water Treatment and Filtration
Sands of various types are used to clean water for drinking, drip irrigation, industrial wash water recycling, swimming pools, and other purposes where it is necessary to clean turbidity, (including oils and grease and heavy metals bound to particulate matter) from the water. Perlite provides an aggressive filtration alternative—either as a replacement or as a supplemental media (depending on the system) in such water treatment systems. Perlite is the go-to filtration media for the high-volume, high-efficiency and water-and-space saving regenerative media filters for pools and other water park attractions.
Perlite has also been used with enthusiastic success as a filtration media in aquarium and pond systems, providing both biological and mechanical filtration. The used media from freshwater systems is readily added to gardens and potting mixes. Perlite takes the place of other loose filtration media like diatomaceous earth, sand, or peat moss.
Grade Matters. The dynamics of particle suspension and transport in water is a function of several variables, including flow velocity, particle concentration, particle size, and particle density. These same variables control the effective capture of suspended particles/solids by a filtration media. Expanded perlite is available in different grade sizes to accommodate the needs of various system and purpose specifications. Often, a grade blend is the ideal solution.
Water Quality and Stormwater Control
Expanded perlite serves to clean storm water as the functional filtration media in catch basin filter systems or mixed with soil and other aggregates and laid into miles of roadside media filter drain channels. Perlite is also used as a lightweight component to specialty soils for vegetated roof systems engineered to reduce rainwater surge and scrub the contaminates and suspended matter. The use of green roofs, roadside media filter drains, and parking lot-fed catch basin filters all reduce the rate of discharge into catch vaults and storm sewers as well as improving the overall turbidity levels in local streams, rivers and lakes by capturing and holding waterborne particulate matter.
