Performance of ecological floating beds and microbial communities under different flow velocities

This study explored the effect of flow velocity on removing pollutants from ecological floating beds (EFBs) using pilot experiments and mathematical models and analyzed the effect of flow velocity changes on the microbial community in the EFBs. First, we observed that EFBs with low flow velocity had a high removal rate for chemical oxygen demand (CODCr), NH4+-N, and total nitrogen (TN). Secondly, we conducted evaluations using the technique for order of preference by similarity to ideal solution (TOPSIS) model and found that EFBs with a flow velocity of 0.91 m/d had a robust, comprehensive removal capacity for CODCr, NH4+-N, and TN. Thirdly, high throughput 16S rRNA sequencing analysis revealed that the microbial community of EFBs at different flow velocities varied significantly. Finally, the microbial community of EFBs with a flow velocity of 0.91 m/d showed the highest richness index, diversity index, and operational taxonomic unit (OTU) number. Moreover, the abundance of the ecological functions responsible for carbon and nitrogen removal was the highest at a flow velocity of 0.91 m/d. The statistical analysis corroborated that flow velocity could affect pollutant removal capacity and microbial community of EFBs.