Today, I wanted to cover a few definitions that can cause some confusion during conversations between operators.
- Nitrification - biological oxidation of ammonium (NH4-N) to nitrite (NO2) and nitrate (NO3) in aerobic wastewater systems. This is a two step process usually accomplished by Nitrosomonas & Nitrobacter sp.
- Denitrification - is the reduction (or use of the bound oxygen by microbes) which converts NO3 or NO2 into N2 gas. Denitrification occurs under anoxic conditions in the presence of soluble organics. Many bacteria can convert NO3 with fewer using NO2 as an alternative electron acceptor. Nitrate/Nitrite are preferentially used as an alternative electron acceptor (O2 source) over SO4, Fe, CO2
- AOB - ammonia oxidizing bacteria (ie Nitrosomonas & Nitrobacter)
- AnAOB or Anammox - organisms that take nitrite (NO2) + ammonium (NH4) and convert it directly to nitrogen (N2) gas. Requires a long sludge age (slow reproduction by these organisms) and proper anoxic conditions for the "shunt" to occur
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