Page 15 - SIMPLIFIED WASTEWATER TREATMENT FUNDAMENTALS_ Advanced Nitrification P1

Advanced Nitrification

Nitrifier Growth Rates

Autotrophs are slow growing organisms. Slower growth rates require

older sludge, or higher MCRT or SRT. Assuming average wastewater

temperatures, Nitrosomonas takes 7 hours to replicate and Nitrobacter

takes 14 hours to replicate.

As you can see in this graph of a newly developing Nitrification

community, it takes days of initial growth for Nitrosomonas to populate

enough to consume ammonia, driving the ammonia residuals down and

Nitrite NO2 residuals up as Nitrosomonas grow. It takes many additional

days of growth for the Nitrobacter to grow to be able to consume the

Nitrite NO2 and convert to Nitrate (NO3).