Study On The Purification Effects Of Artificial Floating-bed And Aquatic Plant For Eutrophic Water

Water eutrophication is a global problem now. In China, water eutrophication is increasingly serious. It not only restricts the economic development, but hazards to human health. At present, it is growing by attention that we control eutrophication by using aquatic plants and artificial floating bed method. Because this way has its good purifying effect, less investment, operation convenient and conducives to rehabilitation and restoration of aquatic ecosystems and so on. This test is designed to research on the capacity of submerged plants and floating plants purifying eutrophic water with outdoor pot method and artificial floating bed renovating eutrophic water pollutants. The results show that:1.Four submerged plants all can grow well in eutrophic water and have a significant effect for removing total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), biochemical oxygen demand(BOD), permanganate index (permanganate),which exist in the sewage. Compared with controls, the average removal rate of the four submerged plants(Elodea Canadensis、Ceratophyllum demersum、Vallasneria asiatica、Myriophyllum spicatum) on TP is76.74%、77.95%、76.07%、70.96%respectively; and the purification rate of TN is57.93%、69.38%、66.13%、66.19%respectively,and Ceratophyllum demersum’s removal effect is the best;the purification rate of COD is38.56%、44.28%、47.10%、39.07%,and Vallasneria asiatica’s removal effect is the best;the purification rate of BOD is49.35%、48.76%、48.99%、44.50%,Elodea Canadensis’s removal effect is the best;the purification rate of Permanganate index is37.86%、39.06%、38.44%、37.78%,the removal effect of Permanganate index is almost the same.2. Compared with the blank, the removal rate of three floating plants (Nymphaea、 Nymphoides Peltatum、Water Caltrop) on TP is82.12%、86.67%、80.84%and on TN is57.98%、59.34%、56.70%, respectively. Nymphoides Peltatum’s removal effect is the best on TN、 TP,then Nymphaea、Water Caltrop; the purification rate of COD is41.16%、45.61%、30.92%,compared with the blank, the removal rate of three floating plants (Nymphaea、 Nymphoides Peltatum、Water Caltrop) on COD increased by17.64%、22.08%、7.39%,Nymphoides Peltatum’s removal effect is the best on COD;the purification rate of BOD is64.29%、56.16%、44.73%,the removal effect is Nymphaea>Nymphoides Peltatum>Water Caltrop;the purification rate of Permanganate index is15.48%、19.04%、14.78%,compared with the blank,the removal rate on Permanganate index increased by1.97%、5.54%、1.27%,the removal effect of Permanganate index is not obvious.3.The results of testing total nitrogen and total phosphorus in the sediment showed that: Sediment itself has certain effect on total nitrogen and total phosphorus adsorption. Compared with the initial value, total nitrogen and total phosphorus of controlled sediment are larger. But at the end of the trial we found that, due to plant roots absorption and microbial degradation, nitrogen and phosphorus contents in the sediments where plant some plants were lower than the initial value. The removal rate of the four submerged plants(Elodea Canadensis、Ceratophyllum demersum、Vallasneria asiatica、Myriophyllum spicatum) on total nitrogen followed by35.89%、25.63%、26.28%、13.38%and on total phosphorus followed by18.48%、32.13%、29.59%、8.48%. The removal rate of three floating plants (Nymphaea、Nymphoides Peltatum、Water Caltrop)followed by40.77%、42.47%、27.28%on total nitrogen and51.00%、51.05%、50.78%on total phosphorus. The result shows that the removal rate of three floating plants (Nymphaea、 Nymphoides Peltatum、 Water Caltrop) on total nitrogen and total phosphorus is Nymphaea>Nymphoides Peltatum> Water Caltrop.4. Selecting Calamus、Zinnia、Aster novi-belgii as the floating-bed plant,artificial floating bed trial is divided into two parts:outdoor potted and planting in the actual reservoir. From the test wo can know the removal effect of the floating-bed on eutrophic water.The removal rate of the floating-bed on TN、TP is40.58%、58.47%,compared with the blank, the removal rate of three floating-bed plants on TN、TP increased by16.22%、6.81%and on COD、BOD、 Permanganate index increased by16.85%、22.63%、18.10%.The results show that three floating-bed plants have good removal effect on eutrophic water.