Man-made Floating Bed Applied On Small Landscape Water Disposal

Small size landscape waters usually are shallow and less mobile,and the water qualities are deeply affected by the environment changing.Under favorable conditions,even few nutrients can fertilize the water in a short time,thus make the algae blooms and the water gives off terrible smell,which brings out worse effect and difficult to restore in short terms.Artificial floating bed is a new ecological water treatment method.It can restore the water quality by assimilating and absorbing of nutrients like nitrogen and phosphorus among aquatic plants.In this research,Iris wilsonii,Acrous gramineus and Eichhornia crassipes are selected to be planted on floating beds,which are made by foam sheets.Static experiment is conducted first,and slight polluted water is prepared with the concentration of total nitrogen is 2.24 mg/L,the concentration of total phosphorus is 0.2mg/L.The experiments has been run 31 days at the temperature in the range of 1-12? to measure the treatment effect of slight polluted water and to record the plant height and the growth in roots.Then 19 days dynamic test has been carried out with the concentration of the total nitrogen and the total phosphorus in the tested water 2.36mg/L and 0.2mg/L.The experiment starts below 5?,the temperature begins to rise afer 10 days and reaches 25? by the end of the experiment.The change of the water quality has been tested,both leaves and roots of the aquatic plants have been observed in similar way.The conclusion is as follows:?1?Low temperature has little effect on the removal of total nitrogen of the three botanies in static test.Acrous gramineus shows the best removal efficiency of total nitrogen,which reaches 92.8%,followed by Eichhornia crassipes with 90.6%,and Iris wilsonii has relatively poor removal effect with 88.7%.All three planted float systems show lower removal rate of total phosphorus,with Iris wilsonii reaches 36.8%,then Acrous gramineus reaches 22.2%,Eichhornia crassipes is the worst with18.2%.One possible reason for the result is that the main existing formsof nitrogen in water is nitrate nitrogen,which can be easily adsorbed and absorbed by the root of plants cultured on the floating bed.Although the stems and leaves of the plants stop growing,their roots can assimilate the nitrogen from water.The phosphorus has complicated forms,mainly removed by degradation of microbes.Microbes can be significantly affected by low temperature,so as to the degradation of phosphorus.?2?The polluted water flow automatically to the three planted floating systems with the hydraulic loading rate of 0.05m³/(m²·d^-1)in dynamic test,which shows that all three systems have removing effect on total nitrogen and phosphorus.The possible reason can be that the nutritional needs by plant growth exceed the emission of pollutants.At the same time,the removal of total nitrogen and phosphorus are low in three planted floating systems,which may caused by short hydraulic retention time and insufficient removal of pollutants.And there is a trend of decrease of the concentration of total nitrogen and phosphorus by the end of the experiment.