Anaerobic Ammonium Oxidation in Waste Water - An Isotope Hydrological Perspective

Excess nitrogen components must be removed from wastewater to protect the quality of the water bodies that it will be eventually discharged to. A conventional wastewater treatment system for nitrogen removal is often involved with two processes, nitrification and denitrification. Nitrification is mostly achieved by complete oxidation of ammonium (NH4+) to nitrite (NO2-) by the appropriate aerobic bacteria and then oxidation of the nitrite to nitrate ion (NO3-) by another variety of aerobic bacteria. Subsequently, the formed nitrate will be reduced to dinitrogen gas under anoxic conditions at the expense of organic carbon and released into the atmosphere as a harmless product (van Dongen et al., 2001). The introduction of oxygen into wastewater for nitrification requires a large amount of energy. Furthermore, the carbon source is often limited in wastewater, so purchasing of carbon source (typically methanol) is necessary too. A newly discovered anaerobic ammonium oxidation (anammox) may circumvent the limitations and open up a new possibility for nitrogen removal from wastewater. The alternative approach is a microbiological involved activity which requires less energy and enables more efficiency on N removal.