Study On Purification Of Representative Organophosphorus By Integrated Vertical-flow Constructed Wetland

Organic phosphorous（Organophosphorus,OP）is an important part of phosphorus and a major player in the Earth’s phosphorus cycle,its levels in the environment have received increasing attention.With the development of industry and agriculture,a large number of artificially synthesized organophosphoru flame retardants and organophosphorus pesticides enter the environment through industrial point sources,flame retardant materials to releaseand agricultural non-point source emissions.Due to the complex structure of synthetic organophosphorus,it is difficult to dissolve in water and be degraded.And has been detected to varying degrees in vegetables,fruits,water,soils,animals and plants.Most organophosphorus are biotoxic and difficult to remove through conventional water treatment techniques,posing a potential threat to water environment and human health.Because of the ubiquitous occurrence and potential adverse effects of organophosphorus in water environment,it is urgent to explore the efficient treatment methods for organophosphorus wastewater.Constructed wetlands（CW）is a sewage ecological treatment system composed of substrates,plants,and microorganisms.As a cost-effective,environment friendly and easy-to-manage biological water treatment technology,It has great potential in removing organic micro pollutants.Thus,Integrated Vertical-flow Constructed Wetlands（IVCWs）was built,to explore the influence of the system on the removal efficiency of organophosphorus and conventional pollutants under combined operating conditions of different inlet water C/N ratio and aeration,observe the migration behaviors and the related mechanism of the organophosphorus in each medium of the wetland system.Finally,the composition and diversity of microbial communities in IVCWs were analyzed,and the effects of organophosphorus exposure on microbial and wetland nitrogen cycling were compared.The results showed that IVCWs had good removal effect on COD（86.06±3.58%）,NH₄⁺-N（64.59±4.38%）and TP（59.51±5.59%）when C/N=3.The addition of carbon source promoted the removal of COD,NO₃^--N and TN,and there was no significant correlation with the removal of TP and NH₄⁺-N.Aeration showed synergistic effect on removal of TP and NH₄⁺-N,antagonistic effect on NO₃^--N and TN,no significant effect COD.Because of the excellent environmental degradability of DDVP,the removal efficiency of TCPP（52.28±11.64%）was significantly lower than that of DDVP（95.33±1.41%）when C/N=3（P<0.01）.There were significant differences in the removal of TCPP under different operating conditions.Compared with the removal rate of TCPP（52.28±11.64%）when the inlet water C/N=3,increasing C/N ratio,aeration value and the two factors together can increase the removal rate to 68.77±2.49%,57.21±1.76%and 89.64±1.94%.By analyzing the cumulative amount of each phase in the system,it was found that the accumulation of TCPP（535.33±413.46ng/g dw）was always higher than DDVP（146.61±113.46ng/g dw）due to the influence of the concentration of pollutants in water and its physical and chemical properties.The concentration of organophosphorus in igneous rock（66.94～435.01ng/g dw）and zeolite（58.71～407.74ng/g dw）is significantly higher than that in soil（19.62～149.94ng/g dw）.In plants,compared with Acorus calamus（432.95ng/g dw）and Typhae latifolia（665.21ng/g dw）,Cyperus alternifolius（1288.82ng/g dw）is more likely to accumulate TCPP.However,DDVP was more easily enriched in Acorus calamus（379.58ng/g dw）.Organophosphorus is mainly concentrated in the roots,compared with TCPP,DDVP is more likely to migrate to leaf tissue.The accumulation of organophosphorus in plants（0.06%）and substrate（2.51%）is limited.So,more attention should be paid to the effects of plants internal degradation,transpiration,microbial,degradation,photolysis and hydrolysis on the removal of organophosphorus.IVCWs is rich in microbial diversity,and the microbial abundance and diversity in soil are higher than that in fillers.Among them,Proteobacteria,Actinomycetes and Bacteroides are dominant in the system.The microbial community structure of soil samples and fillers,CW1 and other treatment cells were significantly different.Organophosphorus exposure increased the abundance and diversity of microorganisms and had a certain effect on microbial structure.At the Phylum and Class levels,the relative abundance of dominant bacteria varies,but the species is almost unchanged.The abundance of Acidobacteria and Acidimicrobiia increased by 1.59～3.57%and1.28～10.08%,respectively.The dominant bacteria in the genus level changed greatly,the Sphingomonas,Azohydromonas and Roseiflexus became the new dominant bacteria.The structure of denitrifying microorganisms was also affected,and the abundance of Nitrospira was stable,while that of Nitrosomonas was increased,which was conducive to nitrification.However,some DNBs were inhibited,and the abundance of Pseudomonas and Flavobacterium was significantly reduced,and the abundance of DNBs decreased from 7.93～24.54%to 1.35～10.06%,which limited the denitrification process.Exploring the removal potential,migration behavior and microbial effects of IVCWs for Organophosphorus has positive significance for the further optimization design of the system to mitigate Organophosphorus pollution.