ABSTRACT
The operation of biological processes may be manipulated to convert ammonia nitrogen to nitrate nitrogen.
The nitrogen that is in raw sewage may be biologically oxidized to nitrate after the carbonaceous oxygen demand is met. This can only occur if the proper aerobic conditions are maintained in the process.
Nitrification may be accomplished in a one- or two-stage process.
In single-stage nitrification, the carbon and nitrogen oxidation steps are combined in a single unit.
In two-stage nitrification, the carbonaceous oxidation step is carried out first in a separate unit, followed by the nitrification step in another unit. This may result in much higher oxygen demand, greater alkalinity consumption, and poorer settling, however.
