Short-Cut Nitrification of Iraqi Municipal Wastewater for Nitrogen Removal in a Single Reactor

Abstract

Nitrogen components removal in wastewater treatment is an updated process that needs a continuous contribution of research. Traditionally, ammonium is removed by two biological ways, denitrification and nitrification. Here, it became necessary to suggest sustainable alternatives to control wastewater treatment strategies. In this work, a single reactor of high ammonium removal over nitrite process was operated, in which ammonium-oxidizing bacteria was used to convert ammonium to nitrite without sludge retention. The system was operated at aerobic conditions and a moderate temperature, at which the higher percentage of the desired ammonium oxidizer bacteria (AOB) over the undesired nitrite oxidizers bacteria (NOB) was achieved. The reactor was tested in a pilot plant scale to treat municipal wastewater with an average influent ammonium concentration value of 147.6 mg/l, flow rate 4.5 l/hr, hydraulic retention time (HRT) 24 hr, temperature 30-35 ºC, dissolved oxygen (DO) concentration 3.7 mg/l, and pH range 6.0–9.0. Removal efficiencies of 65 and 90 % were achieved for ammonium and nitrite, respectively. The Single reactor system is particularly suitable for the treatment of wastewater that contains high ammonium, giving 25% savings of the required oxygen to achieve complete nitrification.