Prospects for Biological Nitrogen Removal from Anaerobic Effluents during Mainstream Wastewater Treatment

Growing interest in the anaerobic treatment of domestic wastewater requires a parallel focus on developing downstream technologies that address nitrogen pollution, especially for treatment systems located in eutrophication-impacted watersheds. Anaerobic effluents contain sulfide and hydrogen sulfide (a corrosive gas), dissolved methane (a potent greenhouse gas), ammonium, and residual organic carbon predominantly in the form of volatile fatty acids. Conventional approaches to nitrogen removal are energy- and chemical-intensive and are not appropriate for application to anaerobic effluents. Innovative, energy efficient nitrogen removal processes are being developed and involve several novel chemotrophic processes. This review provides information about these processes, identifies how to control and retain the most desirable microorganisms, and considers the impact of reactor configuration on performance. Given the complexity of the technologies under development that remove nitrogen from anaerobically treated domestic wastewater, we conclude that computational models can support their development and that sensor-mediated controls are essential to achieving energy efficiency