APHIS Functional Materials
Applications / Filtration

Filtration performance starts with the right filter aid

Grade selection, dosage and addition strategy determine throughput, clarity and cost per litre — often more than the filter itself.

Fig. 1 — Stainless filtration line, detail.
Applications → Filtration
Mechanism

How diatomaceous earth filtration works

Diatomaceous earth works as a filter aid rather than a filter medium. Its porous, irregular particle structure builds a permeable cake that traps suspended solids while allowing liquid to pass — capturing particles far smaller than the pores of the septum beneath it.

1

Precoat

A thin layer of filter aid is deposited on the septum, protecting it from blinding and establishing the initial filtration surface.

2

Body feed

Filter aid is dosed continuously into the incoming liquid, so the cake builds in a porous structure rather than compacting into an impermeable layer.

3

Cake formation

The growing cake becomes the working filtration medium, its permeability determined by the grade selected.

4

Particle capture

Suspended solids are retained throughout the cake depth, not only at its surface.

5

Clarified liquid

Filtrate passes through with the clarity your process requires.

The balance between precoat and body feed, and the permeability of the grade chosen, is where most filtration problems are solved — or created.

Brewing and beverage

Edible oil refining

Used cooking oil processing

Food processing

Industrial liquids and process water

Process economics

What our customers measure

Filter aid selection is judged on outcomes, not on the material specification alone. Improving one of these frequently costs you another — which is why grade selection is a trade-off rather than a ranking.

  • Flow rate Throughput sustained across the filtration cycle
  • Differential pressure Rate of pressure rise and the point of cycle termination
  • Turbidity Clarity of the filtrate against your product standard
  • Filter cycle length Hours or hectolitres between cleandowns
  • Filter aid consumption Kilograms per unit of product filtered
  • Product recovery Liquid lost to the cake at discharge

Selecting a grade

Finer grades generally deliver greater clarity at the cost of flow rate; coarser grades reverse the trade. The right choice depends on your solids loading, target clarity, cycle economics and equipment.

Grade Fine Medium Coarse Custom
Character Lower permeability, higher surface area Balanced permeability and clarity Higher permeability, faster flow Tailored particle size distribution
Direction Polishing and high-clarity duties General-purpose filtration High-solids loading, throughput-driven duties Specific process requirements
Typical Beverage polishing, final clarity stages Beer body feed, edible oil, general process UCO clarification, heavy solids streams Developed against your process data

Indicative direction only. Permeability values published subject to supplier technical documentation. Grade selection should be confirmed by trial under your own conditions.

Technical resources

  • Application Note: Selecting DE Grades for Filtration
    Note
    In preparation
  • Application Note: Understanding Precoat and Body Feed
    Note
    In preparation
  • Technical Data Sheet — Filtration Grades
    TDS
    Coming soon
  • Safety Data Sheet
    SDS
    Coming soon

Other applications

Brewing & Beverage

Precoat, body feed and polishing filtration for breweries and beverage producers.

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Fertilizer & Agriculture

Anti-caking, flowability, carrier and moisture-management solutions for NPK, organic and specialty fertilizers.

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UCO & Oil Processing

Clarification and pretreatment for used cooking oil, feedstock preparation and industrial oil filtration.

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Animal Nutrition & Farm

Carrier systems, anti-caking and moisture management for feed and premix manufacturing.

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Industrial Applications

Adsorption, functional fillers, moisture control and process aids across manufacturing.

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Discuss your filtration process

Tell us what you are filtering, what clarity you need and what you are currently using. We will tell you whether a change in filter aid strategy is worth making.