| In recent years,the problem of urban water ecological environmental pollution has been widely concerned,the State promulgated the "General Office on the promotion of sponge city Construction" on the October 16,2015.In the new guidance opinion of Sponge city construction,the construction of Sponge city,which conforms to the requirements of urban sustainable development according to local conditions,is the main direction to solve the problem of waterlogging in the new period.Constructed wetland,as one of the low-impact development facilities that meet its requirements,not only has the explicit function of ornamental entertainment,but also has the implicit function of urban ecological service and rain flood management,which will be widely used in the construction of sponge city in the future.Based on the research basis and monitoring and analysis of the campus runoff water quality of Shenyang University of Architecture,this paper uses Multistage series constructed wetland to purify it,and studies the influence factors of the system on the purification efficiency and treatment effect of the initial runoff rainwater,and simulates the current situation of hydrological water quality in the campus by using the SWMM model,The operation effect of the constructed wetland system used in this paper is analyzed,and this study can provide technical support for the research of low impact development facilities in Sponge city.The main research contents and conclusions are as follows:(1)11 Typical rainfall events from May 2018 to September were selected to detect the changes of rainwater quality in the initial runoff,and the purification efficiency of multistage series constructed wetland was studied and analyzed.The results show that the removal rate of COD,SS,NH3-N,TN and TP in constructed wetland is 81.18±4.43%,90.23 ± 3.61%,87.71±4.14%,82.99 ± 3.28%and 88.27 ± 6.11%respectively,and the removal rate of each pollutant is higher and stable.The removal of cod,SS,NH3-N,TN and TP from constructed wetland is mainly concentrated in the first three-stage constructed wetland treatment unit,and the removal rate reaches 56.65%,65%,73.5%,69.8%and 82%of the total amount respectively.(2)Through the experiment,the influencing factors of the purification efficiency of constructed wetland were studied and analyzed.The results show that there is a significant correlation between the removal rate of each pollutant and the water temperature of constructed wetland,and it is a positive correlation,and the removal rate of constructed wetland system is significantly higher than that of non-cultivated plants under the condition of planting wetland plants,which shows that wetland plants play an important role in the purification of pollutants by constructed wetlands.;The removal rate of cod,SS and TP in constructed wetland was strongly correlated with the high change of four plant strains,and the removal rate of nh3-n had strong correlation with Shambo,Acorus and Reed strains,and there was no significant correlation with the height of iris plant,and the removal rate of TN was related to the height of Shambo and reed strains.(3)By simulating and analyzing the SWMM model,the total amount of runoff increases with the increase of rainfall recurrence period,the peak runoff becomes larger,the peak of pollutant concentration also becomes larger,and the peak time is similar,according to the calculation of optimal purification efficiency in constructed wetland operation,SS,COD,TN,The maximum removal amount of TP is about 2.714kg,2.67kg,0.0952kg and 0.004kg respectively,accounting for about 4.96%,6.27%,3.18%and 3.5%of the total pollutant load in the whole campus,respectively.It can be seen that constructed wetland has a certain removal effect on the surrounding runoff pollutants and the whole campus pollutants. |
