Nutrient Removal · Nitrification
What Are the Two Steps of Nitrification?
Nitrification is an aerobic biological process. Ammonia-oxidizing microbes change ammonia nitrogen to nitrite nitrogen. Nitrite-oxidizing microbes then change nitrite nitrogen to nitrate nitrogen. Staff often call both groups nitrifiers.
Nitrifiers are autotrophs. This means they use inorganic carbon as their main carbon source. They grow more slowly than the heterotrophic organisms that remove most biochemical oxygen demand, or BOD. Because they grow slowly, they are easier to wash out of a suspended-growth process.
A complete ammonia profile includes influent ammonia, basin or stage results, effluent ammonia, and oxidized nitrogen. Low effluent ammonia with rising nitrate usually shows conversion. High ammonia requires a review of oxygen, solids age, temperature, alkalinity, pH, loading, and possible inhibition.
Nitrite buildup can signal that the two nitrifying groups are not keeping pace. Include nitrite when a profile is incomplete.
Key point: Stable nitrification protects two slow-growing microbial steps, not just one aerated tank.
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Nutrient Removal: Nitrogen and Phosphorus for Wastewater Operators
This page comes from the course. It covers nitrification, denitrification, biological and chemical phosphorus removal, monitoring, return loads and permit limits, one step at a time, with short knowledge checks and a certificate of completion.
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