Ammonium rich wastewater treatment via nitrite: a case study

Several kinds of wastewater are characterized by low carbon to nitrogen ratios and very high ammonia concentrations. Some examples are wastewater coming from sludge dewatering, fertilizer industry, explosive industry or some pharmaceutical processes. A feasible treatment of this kind of effluents is the combination of a partial nitritation, where 50% of ammonia is oxidized into nitrite in an aerobic reactor, and a subsequent anaerobic ammonium oxidation (Anammox), where ammonia is oxidized by nitrite in a second tank. This paper presents the results obtained in a nitritation reactor treating a wastewater from sludge dewatering with different ammonium concentrations in order to obtain a proper ammonium : nitrite ratio of 1:1 suitable for the anammox process and the results obtained during the start-up of an anammox reactor.