Study On Denitrification Of Wastewater Under The Coexistence Of Bacteria And Algae

In this study,we sequenced the metagenomic sequence of water samples from Sewage Treatment and BG11 medium,nitrifying bacteria medium and denitrifying bacteria medium were used to separate chlorella,two strains of nitrifying bacteria XHL1 and XHL2 and one denitrifying bacteria light-flake.The external morphology of chlorella was observed by optical microscope and scanning electron microscope.The phylogenetic trees of the two strains of nitrifying bacteria and denitrifying bacteria were drawn,the taxonomic position of the strains was analyzed,and the denitrifying enrichment medium and nitrifying enrichment medium were used to determine the denitrifying effect of the strains.The denitrification experiment of chlorella was carried out,and the denitrification efficiency of chlorella was measured by adding chlorella to the supernatant wastewater from the secondary sedimentation tank of the wastewater treatment plant.And then adding nitrifying bacteria and denitrifying bacteria chlorella denitrification experiments,the conditions of the bacterium and algae make a trained,and the nitrifying bacteria and chlorella trained to remove sewage nitrogen and denitrifying bacteria and chlorella trained to remove nitrogen in wastewater,finally,respectively for a period of time whether to join the nitrifying bacteria and denitrifying bacteria can improve the denitrification efficiency of chlorella.The results showed that:(1)XHL1 and XHL2 both belonged to Acinetobacter sp baumannii.They had the highest homology with Acinetobacter strain SO20(HQ631961)and Acinetobacter sp.2c56(JN228308),respectively,which were 100%and 99%.The nitrification rate of the nitrifying bacteria XHL1 measured in the medium was 2.99mg·L-1 NH4-n/d under laboratory conditions.When the initial ammonia nitrogen content in the medium was 39.22 mg·L-1 and the initial total nitrogen content was 39.30 mg·L-1,the nitrifying bacteria XHL1 was added to culture for four days,and the ammonia nitrogen content in the medium was reduced to 15.31 mg·L-1 and the total nitrogen final content to 18.41 mg·L-1.The removal rate of nitrobacteria XHL1 to ammonia nitrogen was calculated to be 61%and 53.16%,respectively.(2)Homology of nitrifying bacteria light-flake and Bacterium LYM(JQ328185.1)were found after phylogenetic tree construction.Gas production and nitrogen removal efficiency were measured by denitrifying bacteria enrichment medium.The results showed that obvious bubbles appeared in the tubules after 1 day of culture in the laboratory.When the initial total nitrogen content was 34.51 mg·L-1,the final total nitrogen content was 7.39mg·L-1,and the removal rate reached 78.76%.(3)separation of chlorella is 4.5 microns in diameter,from inoculation culture 4 days growth into the logarithmic growth,the amount of cells from the original 1.58 x 106 cells/mL to rise to 8.75 x 106 cells/mL,will join the rest of the two sink a pool of clear liquid chlorella determine its removal efficiency of nitrogen,ammonia nitrogen content of 43.67 mg/L before never fell to 2.54 mg/L,the removal rate was 94.18%,total nitrogen had never before 86.88 mg/L decreased to 13.52 mg/L,removal rate of 84%.(4)Under the coexistence of nitrifying bacteria and chlorella,the ammonia nitrogen content before treatment decreased from 43.67mg/L to 0.32mg/L,and the removal rate was 99.3%.The total nitrogen in the wastewater before treatment was reduced from 86.88mg/L to 18.9mg/L with a removal rate of 78%.In the controlled experiment of chlorella culture alone and chlorella-denitrifying bacteria culture,the ammonia removal rate of chlorella culture alone and chlorella-light-flake coexisted was 32.84%and 41.6%,and the total nitrogen removal rate was 19.63%and 24.91%,respectively.In this study,both nitrifying bacteria and denitrifying bacteria isolated can have a high removal ability of nitrogen in sewage,and chloreia can also have a good effect on ammonia nitrogen and total nitrogen removal in sewage wastewater.The experiment found that under the condition of co-culture of bacteria and algae,nitrogen removal efficiency can be effectively improved.