Performance and mechanism of pilot-scale carbon fibers enhanced ecological floating beds for urban tail water treatment in optimized ecological floating beds water surface coverage

A pilot-scale carbon fibers enhanced ecological floating beds (CF-EFBs) was constructed. Compared to EFBs without carbon fibers enhancement, CF-EFBs have the better removal of total inorganic nitrogen (TIN), total phosphorus (TP), and chemical oxygen demand (COD), the removal efficiencies were 3.19, 3.49, and 2.74 times higher than EFBs. Throughout the pilot test (under three different coverage rates), the concentrations of COD, TIN and TP of effluent were 18.11 ± 4.52 mgL⁻¹, 1.95 ± 0.92 mgL⁻¹ and 0.13 ± 0.08 mgL⁻¹. Meanwhile, the average removal of TIN, TP and COD from tailwater was 0.96 gm⁻²d⁻¹, 0.07 gm⁻²d⁻¹ and 2.37 gm⁻²d⁻¹ respectively. When the coverage was 30 %, the CF-EFBs had better nitrogen removal effectiveness (TIN purification ability of 1.49 gm⁻²d⁻¹). The enrichment of denitrifying bacteria, such as Aridibacter, Nitrospira, Povalibacter, and Phaeodactylibacter increased denitrification efficiency. These results verified the feasibility of CF-EFBs in tailwater treatment at pilot-scale, which was of great significance for the practical application of CF-EFBs.