The Power of Biological Nitrogen Removal: Why Nitrification and Denitrification Matter

Meeting today’s stringent nutrient limits requires reliable Biological Nitrogen Removal (BNR). At the core of this process are two essential biological reactions—nitrification and denitrification—that work together to control ammonia, reduce total nitrogen, and protect receiving waters. Here’s a streamlined look at why each step is so critical.

Nitrification: Converting Ammonia Safely and Efficiently

Nitrification is a two-stage aerobic process performed by specialized bacteria:

• AOB convert ammonia (NH₃/NH₄⁺) → nitrite (NO₂⁻)
• NOB convert nitrite → nitrate (NO₃⁻)

This process is vital because it:

• Reduces ammonia toxicity, helping meet strict acute and chronic limits.
• Prevents downstream oxygen depletion by oxidizing ammonia in-plant.
• Requires precise control of DO (2.0–3.0 mg/L), pH, alkalinity, and temperature due to nitrifiers’ slow growth and narrow tolerance ranges.
• Consumes alkalinity (~7.1 mg as CaCO₃ per mg NH₄⁺-N), often requiring supplementation.
• Generates nitrate, the electron acceptor needed for denitrification.

Denitrification: Removing Nitrogen Completely

Denitrification is an anoxic reduction of nitrate to nitrogen gas (N₂), permanently removing nitrogen from the system. It:

• Achieves Total Nitrogen (TN) compliance by converting nitrate into a harmless gas.
• Reduces recycle load back to aeration, improving aeration efficiency and reducing oxygen demand.
• Recovers alkalinity (~3.6 mg as CaCO₃ per mg NO₃⁻-N reduced).
• Depends on carbon availability, requiring adequate BOD/COD or external carbon sources.

Integrated BNR: Complete Control of Ammonia and Total Nitrogen

Together, nitrification and denitrification:

• Enable full BNR to meet today’s nutrient limits.
• Minimize eutrophication by reducing both ammonia and total nitrogen.
• Improve energy efficiency by shifting oxygen demand to anoxic zones.
• Rely on proper DO control, SRT management, and internal recycle rates to maintain balanced microbial populations.

Supporting Nitrification and Denitrification with EnviroZyme Solutions

Stable nitrogen removal depends on strong, resilient microbial communities—especially during cold weather, high loading, or process upsets. EnviroZyme offers targeted bioaugmentation solutions to support both sides of the BNR cycle:

• BioRemove AM strengthens nitrifying bacteria to improve ammonia oxidation and stabilize nitrification under stressful conditions.
• BioRemove COD boosts denitrifying heterotrophs by enhancing carbon availability and supporting efficient nitrate reduction.

Together, these products reinforce the key biological pathways that keep nutrient removal consistent, compliant, and efficient.

BioRemove AM

View Product

BioRemove AM

BioRemove AM is a blend of nitrifying bacteria that removes ammonia from wastewater. It is used in a variety of industries that use aerobic treatment to establish, maintain, or restore nitrification. BioRemove AM helps ensure compliance by shortening the recovery time after process upsets and reduces the impact of shock loads on effluent quality.

• Improves nitrification in all wastewater types
• Reduces permit violations
• Promotes consistent and reliable nitrification
• Restores nitrification quickly after upsets

View Product