The Coupling Of Different Plants And Fillers Enhances The Effect Of Constructed Wetland On The Purification Of Brine

With the increasing salt water content,the ecological health of water is seriously threatened.The constructed wetland can effectively manage the salt water,but the increase of salt content limits the play of plants and microorganisms in the system.Therefore,the ecological constructed wetland is taken as the research object in this paper.Five salt-tolerant plants,Canna indica L,Spartina alterniflora Loisel,Scirpus mariqueter,Typha orientalis Presl,and Myriophyllum aquaticum,were selected to construct an enhanced constructed wetland by combining traditional filling with quartz sand and new alkali residue materials.The effects of different system operating conditions,different salinity gradients(low salt water,high salt water)and different packing levels on the purification performance of plant-type constructed wetland were studied,so as to optimize the optimal operating conditions of constructed wetland,screen suitable salt-tolerant plants,and explore the optimal level configuration of alkali slag materials.And through the analysis of enzyme activity in plants,microbial diversity and composition analysis,functional expression and electron microscope scanning,etc.,to discuss plant synergy alkali slag material enhanced the purification mechanism of artificial wetland,analyzes the role of alkali slag material in the system,to achieve optimization of artificial wetland salt-tolerant plants library,alleviate salinity stress,in order to strengthen the microbial membrane,implementation microbial internal structure optimization,artificial wetland long-term stability and applicability.The main research contents and results are as follows:(1)low salt gradient,the analysis of three plants in the process of the experimental screening(canna,flower rice grass,the sea each triangular Biao grass)of low salt water purification research shows that when the HRT = 4 days,C/N = 3:1,under the condition of the CW-Sp device of total nitrogen,total phosphorus and COD removal rate are the best,95.56 %,95.46 %,63.61 %,and the concentration of 1 ‰ to salt stress,qingjiao m grass plant salt resistance optimal Yu Haisan arrises Biao grass is better than that of canna;The results of plant enzyme activity and microbial analysis showed that the contents of POD,CAT and soluble sugar in CW-Sp plants were higher than those in other plants,while the contents of malondione were the lowest,which indicated that the plant suffered less stress damage and had strong anti-interference ability.At the same time,the microorganism diversity of the device is rich,and the microorganism proportion in the device with alkali slag material is orderly optimized,and there is no obvious dominant population of microorganisms,so the advantages of each species can be coordinated to prevent the malicious reproduction of dominant species.(2)Under the high salinity gradient,the purification results of various plant units for high brine showed that under the high salinity stress,the purification efficiency of CW-Sc unit for TN,TP and COD was 45.38 %,78.89 % and 50.32 % at the salinity of 15 ‰and C/N= 4:1.Alkaline slag could cooperate with plants to a certain extent to induce the increase of soluble sugar content,enhance the activity content of protein and protective enzymes in plants,and enhance the resistance of Scirpus mariqueter to salt stress.Microorganisms and the filler surface showed that the plant roots and the CW-Sc device the abundance and diversity of microbial community best,alkali slag material increased rhizosphere microbial community structure of gram-negative bacteria and bacillus,the proportion of optimizing proportion of the microbial community and orderly distribution,collaborative advantage of various strains,promote microbial COG functional richness,strengthen the result of the degradation of pollutants in the wetland.(3)In the purification effect of the filler on the plant-enhanced constructed wetland,HRT=4d,the purification effect of each plant is the best,and the purification effect of the device with alkali slag material is better than that without alkali slag material.When the concentration of low brine is 1 ‰ and C/N is 4:1,CW-Sp-UL has the best purification effect on TN and TP,which is 85.48 % and 91.30 %,and when C/N is 5:1,the best COD removal is 64.09 %.When treated with 15 ‰ high brine and C/N=5:1,CW-Sp-UL plant has the best purification effect on TN,TP and COD,which can be divided into 69.50 %,70.73 % and 41.76 %.At the same time,the laying of alkali slag material can induce the production of SOD and total protein of CW-Sp-UL,reduce the damage degree under salinity stress and enhance the salt resistance of plants.The scanning electron microscopy of alkali slag in CW-Sp-UL plant showed that the density of microorganisms was higher and the biofilm of bacteria was more abundant.Filler surface microbial diversity and Pco A analysis showed that the alkali slag material can increase the quartz sand surface enrichment of microorganism,strain ratio improve special function,optimize the microbial spatial structure,not only for the system to provide high pore carrier,strengthen the enrichment of microorganism,also can alleviate the lack of the traditional artificial wetland lower-level microbial limit.Therefore,plant-filler enhanced constructed wetland can be effectively used as an ecological secondary treatment process to purify brine,provide certain theoretical and technical support for the treatment of low brine discharged into fresh water and high brine in coastal waters,and broaden the application scope of the plant-filler coupled constructed wetland.