Some industrial streams — from fertiliser production, landfill leachate, digestate liquors and certain food processes — carry ammonia well above municipal levels. Nitrifying these streams is demanding: nitrifiers grow slowly, consume alkalinity and oxygen, and can be inhibited by high free ammonia. MBBR suits high-ammonia duty because the retained biofilm holds a stable nitrifying population that would be difficult to maintain in a suspended-growth system at high load.
Managing Inhibition and Demand
At high ammonia concentrations and elevated pH, free ammonia can inhibit nitrifiers, so high-ammonia reactors are often staged to step the concentration down gradually. Nitrification consumes a large amount of alkalinity, which must be present or dosed to prevent the pH from falling and stalling the process. Oxygen demand is also high, making aeration a major design factor.
Where total nitrogen must be reduced, nitrification is followed by denitrification; for very high-ammonia liquors, specialised partial-nitrification routes may be considered, which should be evaluated per project.
High-Ammonia Design Context (indicative literature ranges — confirm per project)
| Parameter | Typical Value | Unit | Notes |
|---|---|---|---|
| SALR — nitrification | 0.5 – 2 | g NH₄-N/m²·d | Temperature-dependent |
| Alkalinity demand | ~7.1 | g CaCO₃/g NH₄-N | Dose if insufficient |
| Oxygen demand | ~4.3 | g O₂/g NH₄-N | For full nitrification |
| Staging | often multi-stage | — | Limits free-ammonia inhibition |
Why a Retained Biofilm Helps
Because nitrifiers are fixed on the carriers, they are not washed out and can build up to treat a high ammonia load. This stability is a key reason MBBR is chosen for concentrated ammonia streams where maintaining a nitrifying sludge would otherwise be difficult.
Frequently Asked Questions
Can MBBR nitrify high-ammonia industrial wastewater?
Why does alkalinity matter so much?
What is free-ammonia inhibition?
Related Pages
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