The recent discovery of anaerobic ammonium oxidation (anammox) revealed the existence of a shortcut in the classic nitrogen cycle where ammonium is converted directly to dinitrogen gas, and removed from the system. After being discovered in a wastewater treatment plant, anammox bacteria have been subsequently characterized in marine, estuarine, freshwater and terrestrial habitats. Anammox process can be used to develop more cost and energyefficient sustainable nitrogen removal systems comparing to those existing today. However, large-scale applications are limited by the a long start-up period owing to the low growth and doubling time of anammox bacteria described so far. In this project, we expect to contribute to a wider application of anammox process in wastewater treatment by improving current available technology with fundamental knowledge of anammox ecology. In this project, we propose to explore the presence of these bacteria in different natural ecological niches. Anammox biomass will be enriched, and microbial community composition, optimum growth conditions, and nitrogen removal efficiency will be studied. We aim to investigate new anammox bacteria and the relation between community structure and process activity. Metagenomic analysis will be use to explore the genetic and physiological diversity of the cultures. In the end, we plan to develop microbial inocula to be used as seeding sources for anammox reactors, and to contribute to a wider application of the anammox process in wastewater treatment.