Effect Of Anions On Spectral Characteristics Of DOM Of The Secondary Effluent Of Urban Wastewater And Its With Cu²⁺

Three dimensional fluorescence spectrophotometry,PARAFAC analysis and UV spectrophotometry were used to reveal the fluorescence components and spectral characteristics of DOM in the secondary effluent of urban sewage,and to explore the effects of the type and concentration of anions on the spectral characteristics of DOM in the secondary effluent and its interaction with the Cu²⁺.In order to find out the composition characteristics of DOM in the secondary effluent and the existence of spectral parameters that can represent the content of organic matter.It provides a data basis for the analysis of the spectral characteristics of DOM and its interaction with heavy metals in the environment.The DOM of secondary effluent existed at least 3-4 independent fluorescent components using by the EEMs-PARAFAC analysis,including low excitation wavelength tryptophan-like,high excitation wavelength tryptophan-like,UV type fulvic acid-like,visible type fulvic acid-like,visible humus and ultraviolet humus.The values of FI,BIX and HIX were in 2.01-2.19,1.02-1.12 and 1.82-3.27 respectively,indicating that the DOM of the secondary effluent mainly came from endogenesis of autogenic microorganisms and self generating sources.There was a significant correlation between TOC and COD,TCOD and SCOD,UV₂₅₄54 andα₃₀₀,α₃₅₀50 andα₃₅₅55 in the DOM of the secondary effluent.The addition of SO₄^2-and Cl^-had little effect on the fluorescence and ultraviolet characteristics of the DOM in secondary effluent except fluorescence intensity.With the increase of adding the NO₃^-concentration,the fluorescence intensity decreased.And the fluorescence peak of the tryptophan-like in the DOM gradually disappeared,and it disappeared after the interaction between DOM and Cu^2+.The excitation wavelengths and the emission wavelengths of the fluorescence peaks representing the humus-like in the ultraviolet light region and the excitation wavelengths representing the humus-like in the visible region got red shift.And the right side of UV absorption peak also got red shift.The additional concentration of NO₃^-was positively correlated with HIX,UV₂₅₃/UV₂₀₃,α₃₀₀,andα₂₅₀/α₃₆₅65 of the DOM and the samples after the interaction between the DOM and the Cu²⁺,while was negatively correlated with BIX and had little effect onα₃₅₀50 andα₃₅₅.With the increase of the Cu²⁺additional concentration,the value of UV₂₅₃/UV₂₀₃,α₃₀₀00 and S_275-29575-295 increased.When the concentrations of NO₃^-in the samples were different,it had a certain effect on analyzing the source and the properties of the different DOMs and the samples after the interaction between the DOM and the Cu²⁺by using fluorescenct parameters and UV parameters.The determinant coefficients of the linear relation between the F₀/（F₀-F）and 1/[C]after the interactions between Cu²⁺and the ultraviolet humus-like,visible humus-like and high excited wavelength tryptophan-like in the DOM of the secondary effluent were respectively 0.8102-0.9976,0.8853-0.9975 and 0.9378-0.9978.And the condition constant logK（L/mmol）were respectively 2.08-2.46,1.84-2.5 and 2.27-2.57,and the proportions of the coordination fluorescent functional groups were respectively19.5%-36.5%,22.5%-33.3%and 24.4%-29.2%.