Nitrification can have the adverse impacts of increasing nitrite and nitrate levels, reducing alkalinity, pH, dissolved oxygen, and chloramine residuals, and promoting bacterial regrowth (Wilczak et al.

How does nitrification affect pH?

As the nitrification process reduces the HC03" level and increases the H2C03 level, it is obvious that the pH would tend to be decreased. This effect is mediated by stripping of carbon dioxide from the liquid by aeration, and the pH is therefore often raised.

Does denitrification raise pH?

In Section 4.3 it is shown that denitrification produces alkalinity, which will result in an increase in the pH value. The magnitude of this increase depends upon the buffering effect of the sewage, because nitrification, on the other hand, produces acidity.