Improved nitrogen removal by application of new nitrogen-cycle bacteria

In order to meet increasingly stringent European discharge standards, new applications and control strategies for the sustainable removal of ammonia from wastewater have to be implemented. In this paper we discuss a nitrogen removal system based on the processes of partial nitrification and anoxic ammonia oxidation (anammox). The anammox process offers great opportunities to remove ammonia in fully autotrophic systems with biomass retention. No organic carbon is needed in such nitrogen removal system, since ammonia is used as electron donor for nitrite reduction. The nitrite can be produced from ammonia in oxygen-limited biofilm systems or in continuous processes without biomass retention. For successful implementation of the combined processes, accurate biosensors for measuring ammonia and nitrite concentrations, insight in the complex microbial communities involved, and new control strategies have to be developed and evaluated.