| Low Impact Development(LID)is a new type of rainwater management technology based on the concept of source control and delayed impact load.The current research on LID mainly focuses on the reduction of rainfall or the removal of traditional pollutants,while ignoring another important substance in runoff rainwater—Dissolved Organic Matter(DOM)and Pharmaceuticals and Personal Care Products(PPCPs)which were frequently found in the water environment in recent years.DOM contains structures such as hydroxyl and carboxyl groups,which easily react with other substances,thereby affecting its solubility and migration in water.Therefore,it is important to study the removal of PPCPs by LID and the interaction between DOM and PPCPs.This paper selected two LID facilities—Soil aquifer treatment system(SAT)and Ecological slope protection(ESP)for simulation experiments to study the removal of two typical antibiotics of PPCPs and traditional pollutants,and discussed the synergistic purification mechanism between DOM and two antibiotics.The simulation experiment showed that the system A(zeolite: ceramsite = 1:1)had better removal effects on multiple pollutants in runoff rainwater than the system B(volcanic rock : medical stone=1:1),and with the increase of the return period,the cell with a filler filling ratio of 40% showed better stability in the removal of pollutants,and the removal rate of SD was the highest(88.27 %),through the comparison and optimization of the fillers in the soil infiltration system.The combination of Excitation Emission Matrix Spectroscope(EEMs),Parallel Factor Analysis(PARAFAC)and Principal Component Analysis(PCA)concluded that four components(C1～C4)were separated from the DOM in the influent and effluent of the soil infiltration system,and the contribution rate of the first principal component dominated by humic-like substances is greatest,reaching 72.67 %.In addition,in the fluorescence quenching titration experiment,it can be obtained by 3D-EEM that SD has a certain quenching effect on the fluorescence of DOM,and it can be further concluded in the synchronous fluorescence spectroscopy that SD has a weakening effect on the fluorescence intensity of protein-like and humic-like substances in DOM.Finally,it can be concluded that there are multiple binding sites for protein-like and humic-like substances in SD and DOM using two-dimensional correlation spectroscopy(Two-Dimensional Correlation Spectroscope,2D-COS),among which,protein-like substances were more compatible with SD,and the results were consistent with the results of Log K values obtained by nonlinear fitting.The simulation experiment of ecological slope protection showed that it has a good removal effect on various pollutants such as ERY,and the removal rate of ERY was the best which reaches 88.27 % at the return period of one year.The analysis of the components of DOM in runoff rainwater before and after the ecological slope protection through EEM-PARAFAC showed that DOM mainly contains three types of humic-like substances(C1,C2,C3)and one kind of protein-like substance(C4).The results of 3D-EEM and synchronous fluorescence spectroscopy showed that ERY has a certain quenching effect on the fluorescence of DOM,and the effect of ERY on the protein-like and humic-like substances in DOM is more obvious.The results of2D-COS further provided information on the interaction between DOM and ERY,and ecological slope protection also changed the sensitivity of DOM to ERY in runoff rainwater.Compared with influent water,the sensitivity of DOM in effluent to ERY was higher.In addition,ERY had more affinity for protein-like substances in DOM,followed by humic-like substances,and this result was consistent with the results obtained by nonlinear fitting.In summary,the removal of DOM in LID was affected by the complex of DOM,SD and ERY,and PPCPs will also change the structure of DOM during the process of flowing through the LID facility,they will interact and influence each other. |
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