Ecological floating bed (EFB) is a green technology for treatment of micro-polluted wastewater. However, its nitrogen removal efficiency is still unsatisfactory. In this study, two EFBs with additional carbon source were established to explore biofilm carriers addition on nitrogen removal and greenhouse gas (GHG) emissions at different C/N ratios and temperatures. Results showed that biofilm carriers addition increased nitrification and nitrogen removal efficiencies in EFB, and more denitrifying and nitrifying bacteria were attached to the biofilm carriers. Higher N2O and CH4 emissions were found in control EFB without biofilm carriers addition which was consistent with higher nitrite accumulation. In addition, high-throughput sequencing analysis revealed that adding biofilm carriers could improve the richness and diversity of biological communities. For EFB with additional carbon source treating secondary effluent, adding biofilm carrier can obtain higher TN removal efficiency and lower greenhouse gas emission.
Keywords: Biofilm carrier; Ecological floating bed; Electron donor; Greenhouse gas emission; Nitrogen removal.
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