MBBR Media Fill Calculator
Moving bed biofilm reactors are sized by carrier surface area, not just volume. Enter tank volume, fill percent, and carrier type to get media volume and total protected biofilm area.
MBBR Carrier Summary
| Item | Value |
|---|
How the calculation works
Formulas
Media volume = reactor volume x (fill % / 100)
Total protected surface = media volume (m3) x specific surface (m²/m3)
Surface per reactor volume = total surface / reactor volume (m²/m3)
Conversions: 1 m3 = 264.172 gal = 35.3147 ft3; 1 m² = 10.7639 ft²
Media volume = reactor volume x (fill % / 100)
Total protected surface = media volume (m3) x specific surface (m²/m3)
Surface per reactor volume = total surface / reactor volume (m²/m3)
Conversions: 1 m3 = 264.172 gal = 35.3147 ft3; 1 m² = 10.7639 ft²
| Common carrier | Protected surface (m²/m³) |
|---|---|
| K1-type (original AnoxKaldnes) | 500 |
| K3-type | 500 |
| K5-type | 800 |
Notes & limitations
Protected surface area is the manufacturer-rated biofilm area sheltered inside the carrier. Total surface area drives the biological capacity rating (often expressed as g BOD/m²/day) — confirm the surface loading rate with the carrier supplier for your wastewater and temperature.
- Fill above about 70% restricts carrier movement and mixing; most designs stay at 30–67%.
- Specific surface values are manufacturer ratings for clean carriers; effective area in service varies with biofilm thickness and wastewater characteristics.
- This tool computes area only. Sizing the reactor for a BOD or ammonia load also needs the supplier’s surface removal rate and the design temperature.
- Keep carrier retention screens in mind — screen sizing and headloss are separate checks.
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