Abstract: Biofilm-based wastewater nitrogen removal reactor is a system mainly making use the metabolic activities of functional microbes in the biofilm to remove wastewater nitrogen to achieve water purification. To understand the microstructure and microbial ecology of the biofilm is of significance to reveal the nitrogen removal mechanisms of the reactor and to promote  nitrogen removal efficiency. This paper introduced the types of biofilm-based wastewater nitrogen removal reactor and the characteristics of biofilm microstructure and related affecting factors, and summarized the research advances on the nitrogen transfer processes and nitrogen removal mechanisms in reactor, the distribution characteristics of functional microbes in  film, the effects of different biofilm-based wastewater nitrogen removal reactors, the running condition,  running time, and substrates on the populations of the functional microbes, as well as the newly-found microbes for wastewater nitrogen removal. The review could provide references for the further study on the biofilm-based nitrogen removal technology.

Key words: Tropical montane rain forest, Floristic composition, Local distribution, Vertical distribution