In municipal wastewater ...

In municipal wastewater treatment, primary wastewater treatment is the biological treatment process, and it refers to the removal of nitrogen compounds, primarily ammonium salts.  This is a three-stage process with two different sets of environmental conditions required.  You don't need to choose the bacteria - they are already there.

The first stage is nitrification, in which nitrifying microbes such as Nitrosomonas species bacteria oxidise ammonium into nitrites.  The second stage, also nitrification, involves microbes such as Nitrobacter species bacteria oxidising the nitrites into nitrates.  Both of these processes require a carbon source, present in municipal wastewater sludge, and oxygen.  The key to managing nitrification is maintaining sufficient oxygen levels to keep the conditions aerobic.  Dissolved oxygen levels are generally measured and controlled via aeration.

The final stage is denitrification, in which denitrifying microbes reduce nitrates to nitrogen, which comes out of solution as a gas.  This occurs in anoxic conditions:  oxygen depleted but nitrate-rich.

Note that this same nitrification-denitrification process is the foundation of the Berlin Method of biological treatment for marine aquaria.

As a biological process, the stability of environmental conditions is paramount.  You can expect the microbial colonies to crash if you have an interruption of more than about four hours to the food or oxygen supply.

There is plenty of literature available on "biological wastewater treatment".  It is, however, important to note that this only forms part of a wastewater treatment process (preliminary treatment is generally required to remove suspended inorganic solids) and that the most important thing to do is characterise your wastewater to determine the appropriate treatment methodology.  If biological treatment is an appropriate part of this treatment, the specifics of your wastewater stream are also required to determine plant capacity and design, with the biological treatment capacity determined not just by the flow rates, but also by the Biological Oxygen Demand (BOD) of your specific wastewater, dependent on both wastewater composition and age of the sludge (biological processes will be occurring before the wastewater arrives at the plant).