Nitrate (NO₃-N) is the end product of nitrification and a regulated pollutant in its own right: it contributes to eutrophication of surface waters and is controlled in groundwater and drinking-water sources. MBBR removes nitrate through denitrification — the anoxic biological reduction of nitrate to nitrogen gas. This page focuses on nitrate as the target pollutant; the denitrification mechanism is detailed on its own page.
Where Nitrate Removal Is Needed
Nitrate removal is required in two broad situations: as the second half of total-nitrogen removal at municipal and industrial plants that nitrify, and as a standalone duty for nitrate-bearing streams — for example certain industrial effluents or contaminated waters where nitrate is the principal nitrogen species. In both cases a biodegradable carbon source drives the reduction, supplied either by the wastewater itself or by dosing.
Because denitrifiers are retained on the carriers, an MBBR denitrification stage is compact and stable, and can be added as a dedicated polishing reactor where an existing plant produces a nitrified but nitrate-rich effluent.
Nitrate Removal Design Context (indicative literature ranges — confirm per project)
| Parameter | Typical Value | Unit | Notes |
|---|---|---|---|
| Mechanism | denitrification | — | Anoxic reduction |
| SALR | 1 – 4 | g NO₃-N/m²·d | Carbon-source dependent |
| Carbon requirement | electron donor | — | Influent or external |
| Condition | anoxic, mixed | — | Mechanical mixing |
Standalone vs. Integrated Nitrate Removal
Integrated nitrate removal is designed together with nitrification as part of a total-nitrogen strategy, with the configuration (pre- or post-denitrification) chosen from the carbon balance. Standalone nitrate removal treats an already-nitrified or inherently nitrate-rich stream and almost always requires a dosed carbon source, since little biodegradable carbon remains. Defining which case applies — and confirming the actual nitrate and carbon levels from data — is the starting point for sizing the reactor.
Frequently Asked Questions
How does MBBR remove nitrate?
When is standalone nitrate removal needed?
Can nitrate removal be added to an existing plant?
Related Pages
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