Exploration on the Purification Effect and Mechanism of Nitrogen and Phosphorus in Water by Different Ecological Floating Beds
[Objective]To study the purification effect and mechanism of different ecological floating beds on nitrogen and phosphorus in wa-ter.[Method]A combined ecological floating bed(CEFB) was constructed by hanging packing biofilm under the roots of water spinach.By comparing the purification efficiency of the eutrophic wastewater by the CEFB with the water spinach floating-bed and the blank control group, and analysing the difference of the counts of bacteria in plant root, the removal contribution of plant absorption, the nitrogen and phosphorus removal mechanisms of CEFB were explored.[Result]Compared with water spinach floating-bed,the removal efficiency of the CEFB on TN, TP, NH4+-N, NO3--N were 71.35％, 70.05％,83.17％, 85.83％, respectively.The removal rate of nitrogen and phosphorus were increased from 13.92％ to 21.08％.The microbes in wastewater quietly multiply on the surface of plant roots and formed a biofilm in nitrogen and phos-phorus removal.The microbial biomass on plant roots in group of CEFB was significantly larger than that of water spinach floating-bed(P<0.05), which indicated that packing biofilms of CEFB could promote microorganism growth and improve the microbial amounts on plant roots.In the CEFB system, the removal contribution of plant absorption on nitrogen and phosphorus was 25.56％ and 5.99％, respectively, which in water spinach floating-bed was 20.24％ and 4.18％, suggestting that plant absorption was not the main function of nitrogen and phosphorus re-moval.[Conclusion]Microbial conversion may be the main mechanism in reduction of nitrogen and phosphorus, and the large microbial bio-mass of CEFB could enhance purification efficiency and system stability.
Ecological floating bedBiofilmNitrogen and phosphorus in water bodiesPurification effectRemoval mechanism
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