Disc Filters for Wastewater Treatment: Applications & Selection
Where rotating disc filters are used across wastewater treatment — and how to select and size the right one for the job.
Disc filters — also called disk filters, rotating disc filters or rotary disc filters — are among the most widely applied tertiary filtration technologies in wastewater treatment. Their combination of a very small footprint, near-zero energy use and simple operation makes them the default choice for a range of applications: municipal tertiary polishing to meet suspended-solids limits, particulate phosphorus removal (paired with chemical dosing), producing feed water for reuse, retrofitting existing plants with little spare space, and energy-conscious upgrades. This page explains where disc filters fit, the key selection criteria — flow, influent solids, target effluent, basin layout and media type — and how to arrive at the right specification for your plant. For the underlying technology, see our disc filtration technology guide; a short plant assessment turns your data into a concrete specification.
Key Numbers
Where disc filters are applied
- Municipal tertiary polishing — the most common use: reducing suspended solids in secondary effluent to meet discharge limits (around 10 mg/L TSS), often as the fastest route to EU compliance.
- Phosphorus removal — combined with upstream iron or aluminium dosing, disc filters capture the phosphorus precipitate to reach stringent total-phosphorus limits.
- Water reuse feed — as a pre-filtration step ahead of disinfection or membranes, protecting downstream stages and improving reuse-water quality.
- Retrofit of existing plants — their compact, low-head layout makes them ideal where there is little spare footprint and the plant must keep running during the upgrade.
- Energy-conscious upgrades — gravity-fed operation keeps energy use per cubic metre among the lowest of any tertiary filter.
How to select a disc filter
The right disc filter follows from a handful of plant parameters. Getting these clear early avoids over- or under-sizing:
- Flow — both average and peak (storm) flow drive the number and size of units and the parallel redundancy (N+1).
- Influent solids — disc filters suit moderate solids (roughly below 50 mg/L TSS); higher loads may need upstream settling first.
- Target effluent — the TSS and, where relevant, TP limits determine the media grade and whether chemical dosing is added.
- Basin layout — available footprint, tank depth and hydraulic head define whether units fit an existing structure or need a new basin.
- Media type — woven mesh, microscreen or pile cloth, chosen for the required cut and the abrasiveness of the influent.
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Last reviewed: September 2026. Regulatory requirements may vary by national implementation. This content is for informational purposes and does not constitute legal or engineering advice.