Using rice straw-augmented ecological floating beds to enhance nitrogen removal in carbon-limited wastewater

Using agricultural biomasses as solid carbon substrates in ecological floating beds (EFBs) can effectively achieve sustainable nitrogen removal for carbon-limited wastewater treatment. This study investigated the impacts of rice straw and various emergent aquatic macrophytes on nitrogen removal efficiency and the bacterial community in EFBs. The results demonstrated that employing rice straw as a solid carbon substrate to support emergent aquatic macrophytes significantly enhanced wastewater nitrogen removal efficiency, concurrently optimizing microbial community diversity and structure. Additionally, chemical changes in dissolved organic matter during the denitrification process of EFBs revealed that straw can release organic carbon as an electron donor to support the metabolic activity of aquatic microorganisms, while aquatic macrophytes can provide a greater variety of organic carbon, enabling a sustainable denitrification process. These findings are beneficial for understanding the underlying microbial mechanism of nitrogen removal in EFBs using agricultural biomass and provide practical guidance for the application of EFBs.