ReviewAnammox-based technologies for nitrogen removal: Advances in process start-up and remaining issues

- There are more than 114 reported full-scale anammox treatment plants around the world.
- Remaining issues are longer start-up, mainstream application and poor effluent water quality.
- Preservation and immobilization of anammox biomass are key to efficient start-up.
- A combined anammox-MFC system is proposed for energy-positive wastewater treatment.

Nitrogen removal from wastewater via anaerobic ammonium oxidation (anammox)-based process has been recognized as efficient, cost-effective and low energy alternative to the conventional nitrification and denitrification processes. To date, more than one hundred full-scale anammox plants have been installed and operated for treatment of NH4+-rich wastewater streams around the world, and the number is increasing rapidly. Since the discovery of anammox process, extensive researches have been done to develop various anammox-based technologies. However, there are still some challenges in practical application of anammox-based treatment process at full-scale, e.g., longer start-up period, limited application to mainstream municipal wastewater and poor effluent water quality. This paper aimed to summarize recent status of application of anammox process and researches on technological development for solving these remaining problems. In addition, an integrated system of anammox-based process and microbial fuel cell is proposed for sustainable and energy-positive wastewater treatment.