Purification And Related Mechanism Of Submerged Macrophytes On Different Water Quality

The situation of water eutrophication in China is still severe.Developing the ecological purification technology of economy and convenient,stable and good environmental benefits to improve the state of eutrophication and recover the water ecological system is of great significance to improve the urban environment quality.And it has a huge market application prospect.The restoration technology of submerged macrophytes is concerned,because of its investment province,good purification effect,convenient operation and no secondary pollution.And the technology is beneficial to the restoration of healthy and stable ecosystem.In this paper,Vallisneria natans,Hydrilla verticillata and Potamogeton Malaianus which are common submerged macrophytes in China were selected as the research object.The removal effect of pollutants by submerged macrophytes under different water quality was investigated in the outdoor natural conditions.And the role of the submerged macrophytes in the process of pollutant removal was discussed.Microbial community structure in the surface soil of the submerged macrophyte system was analyzed through high throughput sequencing technology.And its effect on the removal of pollutants was discussed.The decontamination mechanism of the three kinds of submerged macrophytes was invesgated.The kinetics equation of pollutant degradation were fitted.The main conclusions are as follows:（1）Vallisneria spiralis,Hydrilla verticillata and Potamogeton Malaianus have obvious effect on water purification.The three kinds of submerged macrophytes can be used for remediation and pollution control of related water bodies.In the water test of IV,inferior V and first grade A strandard,the effluent indexes of TN,NH₃-N,TP and COD_cr in the three kinds of submerged macrophyte systems can reach the III standard of the surface water environmental quality standard（GB3838-2002）.In the water test of V,the effluent indexes of TN,NH₃-N,TP and COD_cr in the three kinds of submerged macrophyte systems can reach the IV standard of the surface water environmental quality standard（GB3838-2002）.In the water test of first grade B standard,the effluent indexes of TN,NH₃-N,TP and COD_cr in the three kinds of submerged macrophyte systems can reach the V standard of the surface water environmental quality standard（GB3838-2002）.There were no apparent different of the water purification effect by three kinds of submerged macrophytes in micro polluted water,while the water purification effect by Hydrilla verticillata in heavy polluted water was better than that by Vallisneria spiralis and Potamogeton Malaianus.（2）In different water quality trials,the biomass of Vallisneria spiralis,Hydrilla verticillata and Potamogeton Malaianus increased.The biomass growth of Three Submerged Macrophytes is classified as:Hydrilla verticillata>Vallisneria spiralis>Potamogeton Malaianus.The accumulation of carbon,nitrogen and phosphorus in submerged macrophytes increase with water quality deterioration.The order of carbon,nitrogen and phosphorus accumulation of three kinds of Submerged Macrophytes is Hydrillaverticillata>PotamogetonMalaianus>Vallisneriaspiralis.Nitrogen accumulation in submerged macrophytes accounted for a lower proportion of TN removal in water.The order of nitrogen and phosphorus accumulation of three submerged macrophytes accounted for the largest proportion of TN and TP removal in water is Hydrilla verticillata>Potamogeton Malaianus>Vallisneria spiralis.（3）Proteobacteria and Acidobacteria are the major microorganisms in the matrix of submerged macrophyte system.The highest microbial content related to nitrogen treatment is denitrification related bacteria,accounting for 71.53%of the total nitrogen related bacteria.Among them,Nitrospira is the main of nitrifying bacteria,and Sulfuricurvum is the main of denitrifying bacteria.Pseudomonas is the most important phosphorus removal microorganism in submerged macrophyte system.The existence of submerged macrophytes can provide a good living environment for microorganism with different oxygen demand.（4）The first order kinetic model was used to sort out the test data.When the submerged macrophytes fitted the degradation kinetics equation of TN,TP and COD_crr with three terms,the R² was the highest and the correlation was the best.Thus a series of TN,TP and COD_cr degradation kinetics equations were obtained.