It is an important issue to remove nitrogen components from wastewater nowadays since these components can be toxic to aquatic life, and cause oxygen depletion and eutrophication in receiving water. Biological nitrification and denitrification is the most commonly used process for nitrogen removal from wastewater. Nitrification is the autotrophic oxidation of NH4-N, first to NO2-N and then, to NO3-N, whereas denitrification is the heterotrophic and anoxic conversion of NO3-N, first to NO2-N and then, to gaseous nitrogen compounds. In both, nitrification and denitrification process, nitrite (NO2-N) is an intermediate. Shortcut nitrogen removal via nitrite pathway, as one of the cost-effective and sustainable biological nutrient removal process. This process, compared with the traditional biological nutrient removal process, results in saving up to 25% of oxygen consumption in the nitrification stage, and 40% of the carbon source requirements in the denitrification stage. Factors to achieve stable partial nitrification, in literature include: low dissolved oxygen concentration, high temperature, appropriate sludge retention time, high substate concentation, free ammonia and free nitrous acid inhibition.