Interaction Between Dissolved Organic Matter And Endocrine Disruptors From Landfill Leachate

Leachate pollutant from MSW landfills has been a major environmental concern.The purpose of this research was to characterize the chemical/physical and orgnic/inorganic composition of leachates from three landfills in China,labeled as R-landfill (the landfill of about 5 landfill ages in Wuhan),J-landfill (closed landfill in Wuhan) and H-landfill (located in Yichang with 5-10 ages) and understand the interaction mechanisms between dissolved organic matter (DOM) and environmental endocrine disruptors (EEDs).Leachate DOM was characterized by fractioned using Ultrafiltrate (UF) and XAD resin and analyzed qualitatively and quantitatively using combining analysis methods such as UV, fluorescence,GPC,HPLC,FTIR spectroscopy,element analysis,1HNMR and Pyrolysis-gas chromatography/mass spectrometry (Py/GC-MS).The results showed that the compositions of DOM were correlated to landfill age,waste content in landfill and rainfall in landfill region. Fulvic acid in DOM,refractory organic matter,dominated in all samples.High H/C and N/C in leachate DOM (especial in R-landfill) indicated the dominant biochemical process.In older J-landfill had relative lower amount of carbohydrates and proteins by Py/GC-MS analysis,andconcentrated high aromaticity structure of DOM may be the main reason why the residue COD isdifficult to be removed.A comprehensive determination of the composition of the organic pollutants was obtained byGC/MS analysis.The wider variety of organic substances were identified and attributed to naturalor xenobiotic waste components.Apart from plant material-derived compounds and degradationproducts of peptides,carbohydrates and lignin,numerous xenobiotic substances were identifiedand attributed to the groups of pharmaceuticals,estrogenic compounds (nature and synthesis),plasticizers,pesticides or chlorinated aromatics.BPA,E1,E2 and six Phthalates as targetscompounds were detected in three raw leachates and their treatment samples.The concentrationsof BPA and DEHP were usually high during the whole process up to 127.66 and 232.5μg/L andthe concentrations of them were lower in September because of rainfall dilution effect.The leachates from H-landfill contained relatively lower concentrations of BPA compared with R andJ-leachates.A slight positive correlation was found between BPA concentrations and DOC andthe major portion of the BPA in leachates was found in real dissolved fractions while DEHP infraction 0.45μm-1000Da.Nine classes of organic matters were used to discriminate substancesaffected by degradation processes and persistent compounds.The result suggested that aconventional treatment processes such as biological treatment,coagulation,sedimentation,sandfiltration,and activated carbon adsorption were not suitable to eliminate the potential estrogenictoxicity completely.Therefore,advanced treatment process should be adopted such asUV/catalysis.DOM plays a significant role on the fate and transformation of organic pollutants.Sorption anddegradation of targets EEDs including BPA,E2,E1 and the mixture of six PAEs (DMP,DEP,DBP,BBP,DEHP and DnOP) have been investigated in the laboratory.The adsorption isotherm ofBPA, E2 and E1 by DOM fits Freundlich model well.Both the unreacted DOM and their EEDsinteraction products were analyzed by FTIR,1HNMR and ESR.The results suggest that multiplebinding mechanisms may occur simultaneously in the adsorption process with the formation ofionic bonds,hydrogen bonds and charge-transfer bonds.Finally the removal or degradation of EEDs was discussed,a simple technique to removePAEs was proposed,which has a potential to remove organic micropollutants associated withDOM.BPA,E2 and E1 can be removed or degradated by photocatalysis oxidation under sunlightand UV with TiOz irradiation.The direct and indirect photolysis of BPA,E2,and E1 wasinvestigated in the absence and presence of DOM from three landfills.EEDs degradation bydirect photolysis under sunlit irradiation was significantly slower than that in the presence ofDOM.However,distinguishing differences in indirect EEDs photolysis with DOM from directphotolysis were observed primarily due to competitive light absorption and the quenching ofEEDs*.The influence of DOM on the photolysis of EEDs is small as compared with that ofDOM structure.J1-3 increased more carbon normalized rate constant than the other twoinvestigated.The products formed during degradation were detected using UV-Vis spectroscopy,FT-IR,HPLC and GC/MS.The pathway of BPA degradation by TiO₂ photocatalysis wasproposed and the estrogenic activity of E₂ degradation products was discussed.The estrogenicactivity of E₂ should be almost lost concurrently with the initiation of the photocatalyticdegradation.Therefore,TiO₂ photocatalysis could be applied to water treatment to effectivelyremove natural and synthetic estrogens without producing biologically active intermediaryZproducts.