Abstract: A biological grid device, consisting of hydrophytes and packings, was constructed to reinforce treatment of eutrophic river water. A pilot scale experiment was performed to study the influences of aeration and packing types on pollutant removal and characteristics of microbial community on biomembrane. Seven reaction tanks were parallelly connected and the process was continuously influent and effluent, with water inflow designed to be 6 m3· d-1. The results show that packings, working as microbial carriers, have important roles on pollutant removal. Reaction tanks with packings have higher removal efficiencies of COD，Cr，total N and NH+4，N, with 42.1%～52.2%, 24.4%～47.8% and 58.7%～71.4% higher than those with none packing tanks, respectively. Compared with suspended packings, combined packings and the new type packings have complicated microsetting, thus have higher removal efficiencies of total N. At the same time, intermittent aeration have higher pollutant removal efficiency for all three packings than none aeration ones. ERIC-PCR fingerprinting analysis shows that similar band patterns have been found from biofilm samples of the three kinds of packings before the maturity of biofilms. Along with the maturity of biofilms and system stabilization, biofilm band patterns are divided into two types，suspended carriers have one kind and the combined packings as well as the new type packings have the other. At the same time, microbial population diversity increases and pollutant removal efficiency goes up for all the three packings types. Intermittent aeration tanks （No. 3 and No. 5） have more microbial population diversity than none aeration ones (No. 2 and No. 4), which are in favor of pollutant removal. Therefore，along with stable operation，microbial population diversity index increases and system is in good condition.

Key words: biological grid device, biofilm, eutrophic water, aeration, ERIC-PCR, biological grid device, biofilm, eutrophic water, aeration