Experimental Study On Purification Of Eutrophication Water By Immobilized Algae And Aquatic Plant Floating Bed

Since the introduction of algae in the purification of nutrients such as nitrogen and phosphorus in sewage in the 1950s,research on the use of algae for nitrogen and phosphorus removal has received increasing attention from scholars at home and abroad.As an efficient and convenient way to recover algae,immobilized algae has a good effect on nitrogen and phosphorus removal of sewage.Ecological floating bed technology has become a kind of low cost,simple operation and good landscape benefits.Applying a wide range of ecological treatment techniques,this topic combines immobilized algae with artificial ecological floating bed to explore its purification effect on eutrophic water.In this experiment,the chlorella,the four-tailed cyanobacteria,and the cyanobacteria were cultured,and the algae were cultured until the logarithmic phase,and the algae balls were placed in artificially configured sewage.The results of nitrogen and phosphorus removal experiments showed that the immobilized chlorella had the best removal effect on nitrogen and phosphorus,and the removal rate of nitrogen and phosphorus reached 80.6%and 60.5%,respectively.Therefore,the immobilized chlorella was used in the subsequent experiments.By studying the effects of algae cell density,pH and temperature on the nitrogen and phosphorus removal effects of immobilized Chlorella,it was found that the density of algae cells had an obvious effect on the nitrogen and phosphorus removal of immobilized Chlorella.The larger the Nitrogen and Phosphorus removal rate,the higher the density of the rubber sphere structure is,and the algae cell utilization rate is low.The actual water treatment should adopt the algal rubber sphere with medium cell density(7 X 106/ball).When the pH was in the range of 6.5?8,the removal rate of nitrogen and phosphorus was the highest when the pH was 7.5,which was 91.1%and 87%,respectively.When the pH continued to increase,the growth of chlorella was inhibited.The removal rate of nitrogen and phosphorus decreases.The pH range suitable for the growth of chlorella is 7?7.5.When the temperature is above 24?,the effect of temperature on the denitrification and dephosphorization of chlorella is relatively small,the removal rate of ammonia nitrogen can reach 90%,the removal rate of phosphorus is 86%,when the temperature is lower than 18?.The removal efficiency of nitrogen and phosphorus by chlorella decreased significantly.The canna and vetiver were selected as aquatic plants,and the combined floating bed was constructed together with the immobilized chlorella to explore the absorption effect of different combined floating bed system and single floating bed system on nitrogen and phosphorus in sewage.The results showed that the immobilized chlorella-aquatic plant combination had significant effects on the removal of nitrogen and phosphorus in water.Compared with the blank group and single plant group,the immobilized chlorella dominated the absorption of nitrogen and phosphorus.The 7d removal rates of nitrogen and phosphorus in the immobilized chlorella-vetiver grass combination floating bed were 95%and 87.5%,respectively.The 7d removal rates of nitrogen and phosphorus in the immobilized chlorella-cancer combination floating bed were 90.7%and 90.5%,respectively.The overall results of the experiment showed that the immobilized algae-aquatic plant combination had a good removal effect on nitrogen and phosphorus nutrients in the sewage.