Work out mbbr media volume instantly with clear inputs, formula shown and shareable results.
Moving bed biofilm reactors are sized on surface area rather than volume: required area is the load divided by the surface loading rate, typically 5-8 g BOD/m2/day for carbon removal and 0.8-1.5 g N/m2/day for nitrification. Media fill is capped around 60-70% so the carriers can circulate freely.
Biofilm area
Area (m2) = BOD load (g/day) / surface loading rate (g/m2/day)
Volumes
Media volume = area / specific area; tank volume = media volume / fill fraction
Above about 67% the carriers no longer circulate freely, leading to dead zones, uneven biofilm and clogging of the retention screens. Most designs use 40-60%.
No sludge return, no bulking risk, compact footprint and resilience to load shocks. It needs a downstream solids separation step but does not depend on sludge settleability.