[Research Progress of Biochar and Natural Minerals in Nitrogen Cycling Process of Constructed Wetlands]

Nitrogen compounds， as one of the important pollutants in water bodies， have caused significant impacts on the ecological environment and human health because of their excessive discharge. Therefore， it is particularly important to pay attention to controlling nitrogen compounds in wastewater. Constructed wetlands （CWs）， as a flexible and efficient wastewater treatment system， play a crucial role in the nitrogen cycling process. Substrate is an important component of CWs， and the selection of its species is closely related to the nitrogen removal performance of CWs. In this context， biochar and natural minerals were introduced as substrates for nitrogen removal process of CWs. The impacts of characteristic parameters of biochar and natural minerals， such as filling method， filling quantity， and particle size， on the overall nitrogen removal performance of CWs were reviewed. Furthermore， the effects of both on the key nitrogen removal processes， such as nitrification， denitrification and anaerobic ammonia oxidation （ANAMMOX） in CWs were investigated in depth， and the mechanisms by which both promote the overall nitrogen removal processes of CWs were clarified. Finally， the problems of both in filling CWs from economic and environmental perspectives were discussed and optimization suggestions were given. The research can provide rational basis for the construction of CWs， ensuring their effectiveness and long-term sustainability.