One of the strongest commercial arguments for MBBR is that it can reuse existing tankage. An aeration basin, an out-of-service clarifier or a redundant contact tank can often be converted into an MBBR by installing carriers, carrier retention screens and, where needed, an adapted aeration grid. Because the civil structure already exists, the capital and programme are focused on process equipment rather than new construction. Suitability depends on the tank geometry, water depth and structural condition, which are verified per site.
What makes a tank suitable
A candidate tank needs a geometry that supports good carrier circulation, sufficient water depth for effective aeration, and points where retention screens can be installed to keep carriers in the reactor. Tanks that are very shallow or awkwardly shaped may need internal modifications. The existing structure must also be sound enough for the intended service life.
Where a tank is suitable, the retrofit typically installs an aeration grid sized for oxygen transfer and carrier movement, screens on the outlets, and the carrier fill required for the treatment target.
Existing-Tank Suitability Checks (site-specific — confirm per project)
| Parameter | Typical Value | Unit | Notes |
|---|---|---|---|
| Water depth | adequate | m | For aeration + circulation |
| Tank geometry | favourable | — | Supports carrier movement |
| Retention screens | installable | — | Keep carriers in reactor |
| Structural condition | sound | — | For intended service life |
Frequently Asked Questions
Which existing tanks can be converted to MBBR?
What has to be added to an existing tank?
Why is reusing tanks cost-effective?
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