Nitrification & Denitrification

Ammonia Oxidation (Nitrification Step 1)

Nitrosomonas bacteria convert ammonia (NH3) to nitrite (NO2-).

Nitrite Oxidation (Nitrification Step 2)

Nitrobacter bacteria convert nitrite (NO2-) to nitrate (NO3-).

Anoxic Denitrification

Facultative bacteria convert nitrate to nitrogen gas in low-oxygen zones.

Temperature Sensitivity

Nitrification rates drop sharply below 15°C.

Nitrifier Growth Kinetics

Nitrifiers grow far slower than heterotrophs, which is why SRT, not HRT, governs nitrification capacity.

pH Sensitivity of Nitrifiers

Nitrification rate drops sharply below pH 6.5 and above pH 8.5, independent of temperature or DO.

SND (Simultaneous Nitrification-Denitrification)

Nitrification and denitrification occurring in the same basin via DO gradients within the floc itself.

Step-Feed Nitrogen Removal

Splitting influent flow across multiple feed points to create internal anoxic zones without extra recycle pumping.

Bioaugmentation for Nitrification

Adding cultured nitrifying bacteria to speed recovery after a toxic event or seasonal washout.

Ammonia-Based Aeration Control (ABAC)

Uses real-time effluent ammonia readings, not just DO setpoints, to control blower output.