Research progress and prospects in nitrogenous wastewater treatment technologies

Nitrogenous pollutant discharges are rising with urbanization and industrialization， and their untreated release worsens aquatic nitrogen pollution. Currently， nitrogen removal from municipal and industrial wastewater is transitioning from an energy-intensive model to strategies emphasizing pollution reduction， carbon mitigation， and synergistic efficiency. Green and sustainable nitrogen removal technologies represent a key research frontier in water pollution control. This review systematically examined nitrogen pollution in China's wastewater， characterized nitrogen-laden industrial effluents， and highlighted challenges such as wide concentration ranges， complex compositions， and treatment recalcitrance. Based on this analysis， this paper comprehensively reviewed the principles and applications of advanced nitrogen removal technologies， including physicochemical， biological， electrochemical/bioelectrochemical， and advanced oxidation processes. Their treatment efficiency， advantages， and limitations were analyzed， with special emphasis on the application of advanced oxidation processes for refractory nitrogenous pollutants. Future efforts should prioritize adopting low-energy， low-chemical-consumption biological nitrogen removal processes， integrate electrochemical and advanced oxidation processes with conventional methods， enhance overall treatment efficiency， and reduce costs. These advancements are pivotal for achieving China's Dual Carbon Goals and advancing sustainable development.