AbstractA series of floating beds consisting of biounits were constructed for eutrophic water treatment in the field. Dynamic changes in water quality under each treatment were monitored to investigate treatment performance, and the mass balances of nitrogen (N) and phosphorus (P) in the integrated ecological floating bed (IEFB) were studied to reveal the interaction mechanisms operating within the beds. Water quality improvement was examined under different biounit arrangements to optimize configuration parameters. The test results showed that the concentrations of total nitrogen (TN) and total phosphorus (TP) declined linearly during the first 6 days, and the highest removal of TN (58.9%) and TP (59.1%) was observed in the IEFB, in which TN and TP removal rates reached up to 0.407 and 0.041 mg·L−1·day−1, respectively. The mass balance analysis of N/P indicated that TN was mainly removed through microbial denitrification (72.5%), with sedimentation accounting for 59.1% of TP removal. Compared with each independent biounit, the IEFB composed of multiple biounits exhibited superior performance in eutrophic water purification. The removal of N and P in the IEFB mainly depended on the bacteria and algae attached to the artificial carrier medium. Meanwhile, the aquatic animal unit enhanced the removal efficiency of TN and TP from the water by means of inorganization of particle N and P, which simultaneously improved water diaphaneity.