Choosing the right filtration solution: How perlite and diatomaceous earth mineral filter aids drive performance across filter types
Filtration plays a critical role in industries ranging from food and beverage to pharmaceuticals, water treatment, and advanced industrial applications. Yet, with many filter types and processes available, it can be challenging to determine which solution is best for a specific application.
Filtration can seem complex, but at its core, it comes down to a few distinct approaches. Each method has unique strengths depending on the particles being removed, the liquid being treated and the quality requirements of the final product. But with so many methods available, how do companies choose the right solution?
The answer often comes down to the media. Among the most effective and widely trusted are mineral filter aids such as perlite and diatomaceous earth. Their naturally porous structures, inert chemistry, and versatility make them indispensable across industries where clarity, consistency, and efficiency are non-negotiable.
Depth filtration: The power of perlite and diatomaceous earth
The filtration process, whether it involves pressure or vacuum, typically consists of three basic steps: precoat, filtration with body feed, and filter cleaning.
Precoating protects the filter septum, provides initial clarity, and facilitates cake removal. The selection of precoat grade is critical to ensure optimal flow and cake stability during filtration.
Body feed, when added continuously alongside the filtered fluid, helps to maintain porosity, resists compression, increases solids holding capacity, and further lengthens filtration cycles. The dosage of body feed is typically proportional to the concentration of suspended solids and varies based on the application. An optimal grade is one that consistently provides the highest throughput while meeting target clarity.
Finally, after filtration is complete, a properly precoated filter can be easily cleaned mechanically or through backwashing to prepare for the next filtration cycle.
Perlite:
Perlite is a natural volcanic glass that is expanded and milled to create a maze of microscopic pathways, which are optimal for filtering liquids. Its lightweight and chemically inert nature provides stable filtration performance and high throughput. Harborlite filter aids are characterized by a carefully controlled particle size distribution and permeability to meet the needs of a wide variety of filtration applications. Perlite is ideal for applications requiring high solids removal and for filtering gelatinous solids.
Diatomaceous Earth (DE):
Formed from the fossilized remains of microscopic diatoms, DE’s intricate structures capture even the finest particles, delivering clarity and microbiological stability. Imerys, the world's leading DE producer, engineers products like Celite and Kenite, offering various grades (natural, calcined, flux-calcined) to suit specific filtration needs. DE is ideal in applications where high clarity is required and to ensure minimal product loss.
Solid/Liquid Separation Equipment:
Various types of filters are employed across industries, and the choice often depends on application requirements like cake type, particle size, and operational needs. Pressure filtration forces liquid through a filter under positive pressure. Common pressure filters, including plate and frame, vertical and horizontal tank leaf, and candle, are ideal for removing fine solids, capturing better solids, and producing lower moisture waste cakes. Vacuum filtration pulls liquid through a filter using a vacuum. Rotary vacuum filters are ideal for filtering large volumes with high solid concentrations of compressible solids.
How they work:
- Slurry pumped into frames
- Filter pressed together with
- Filtrate drains out of plates while cake remains
- Cake is then discharged
Why are they used:
- Versatile - Can add/remove plates to adjust filter area
- Lower cost
- Can manage high solids & sludges
How they work:
- Cylindrical filter elements are mounted vertically to a header sheet inside the tank
- Filtrate typically enters from the tank bottom, and exists through the header
- Filter cakes build on the outside of the cylindrical tube elements
Why are they used:
- Higher surface area than leaf filters with a low footprint
- Can add numerous candle elements or different sizes
- Easy to backwash candles to discharge cakes
How they work:
- Filter cakes form on large, parallel filter screens
- Filtrate passes through the filter leaves and out through the discharge
- Waste cake is washed or shaken off and drained at the bottom
Why are they used:
- Lower footprint than horizontal tanks
- Higher surface area than P&F
- Lower cost than candle filters
How they work:
- Similar filtration process to vertical tank leaf filters
- Tanks may open to allow washing. Internal sluicing is also possible.
Why are they used:
- Larger than vertical tanks and capable of fitting more vertical leaves
- Greater filtration surface area
How they work:
- Pre-coat is applied to a rotating drum
- During filtration, slurry is pumped into the receiving bowl
- Vacuum pulls filtrate through the pre-coat and filter septum
- As the drum is exposed, the cake dries
- A knife then shaves dried solids off, re-exposing the clean filter aid
Why are they used:
- Filtrations with large volumes
- Capable of handling high solid concentrations
- Long filter cycle times (days/weeks)
Different industries rely on different filtration equipment, but in every case, mineral filter aids make the difference between basic operation and optimized performance. The table below highlights where perlite and DE deliver value and why Imerys’ engineered minerals are trusted worldwide.
| Equipment Type | Typical Applications | Role of Perlite and DE | Why Choose Imerys Minerals? |
| Plate and Frame Filters | Beer, wine, juice, syrups | Form a porous precoat on the filter to prevent blinding, deliver consistent flow, and achieve brilliant clarity | Consistent particle size to ensure ideal permeability and inert minerals to maintain taste and chemical integrity |
| Vertical Tank Leaf Filters | Edible oils, sweeteners, chemicals | Build a stable filter cake on vertical leaves, capturing fine impurities efficiently | Neutral, food-grade minerals maintain taste/chemistry integrity while increasing throughput |
| Horizontal Tank Leaf Filters | Large-scale edible oil and sugar refining | Support even cake formation across horizontal leaves, enabling high throughput and efficient cake discharge | Tailored mineral grades optimize flow, reduce maintenance downtime, and boost operational efficiency |
| Candle Filters | Pharmaceuticals, biotech, high-purity food ingredients | Precoat candle elements with perlite or DE to achieve high purity, extend cycle life, and protect downstream membranes | Pharmaceutical-grade quality, engineered for sterility-critical operations |
| Rotary Vacuum Filters | Sugar syrups, juices, wastewater, chemical slurries | Create a continuous precoat layer on rotating drums, enabling uninterrupted clarification of large volumes | Perlite and DE support scale, sustainability, and process efficiency |
The Imerys advantage
As a global leader in mineral solutions, Imerys delivers perlite and diatomaceous earth filter aids engineered for consistency, safety and sustainability. Our technical experts collaborate with customers to optimize equipment performance, whether that means enhancing brilliance in beverages, reducing costs in edible oil refining, or achieving sterility in pharmaceuticals.
By combining mineral science with process expertise, Imerys ensures producers don’t just filter their products; they filter with confidence.
Contact us to learn more about our product range for your filter aid needs.
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In early October, the Saint-Bauzile diatomite site welcomed local authorities and members of the wider community for a series of open days. The events provided an opportunity to highlight the site’s strategic operations and reinforce relationships with local stakeholders following its integration into Imerys earlier this year.
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