Disc filters are gravity-fed, continuously rotating filter units with cloth or woven media on vertical discs. They replace or supplement the secondary clarifier after an MBBR, producing a low-TSS effluent in a fraction of the footprint. The combination MBBR + disc filter is particularly attractive for compact plants or those requiring tertiary-quality effluent without a separate tertiary step.
Why disc filters suit MBBR
MBBR effluent solids can settle poorly in gravity clarifiers, but disc filters operate by surface filtration: solids are captured on the cloth as water passes through by gravity, and a rotating backwash cleans the cloth continuously. This makes them indifferent to particle density — light biofilm fragments are removed as effectively as heavy flocs.
The footprint of a disc filter is typically a small fraction of a secondary clarifier. They run at low head (gravity feed), consume little energy, and produce a consistent effluent TSS. Coagulant dosing ahead of the filter can improve performance if very low TSS is needed. The combination is a natural fit for R+F FilterElements’ disc and drum filter product range.
Design considerations
MBBR + disc filter design (indicative — confirm per project)
| Parameter | Typical Value | Unit | Notes |
|---|---|---|---|
| Filtration type | Surface (cloth media) | — | Gravity-fed, continuously backwashed. |
| Footprint | Much smaller than clarifier | — | Compact installation. |
| Effluent TSS | Low | mg/L | Suitable for tertiary-quality discharge. |
| Chemistry | Optional coagulant | — | For very low TSS targets. |
Frequently Asked Questions
Can a disc filter replace the secondary clarifier entirely?
What effluent quality does MBBR + disc filter achieve?
How does disc filtration compare to DAF?
Related Pages
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