| Industrial enterprises and domestic sewage in the urban section of inland rivers in the arid area of Xinjiang are the important hidden dangers of river water environment risks.Obtaining the stable fluorescence spectrum characteristics of dissolved organic matter(DOM)of enterprises involved in sewage is the basis for rapid traceability of rivers and other water bodies.The three-dimensional fluorescence technique has the advantages of high sensitivity,good selectivity,simple operation and no damage to the sample,which can be used as a suitable characterization technique for DOM.Because of the complex composition and diverse structure of DOM,it is easy to be affected by pH,metal ions and other external environment,which leads to the change of three-dimensional fluorescence spectrum of DOM under different environmental factors,such as the change of fluorescence peak position,the change of fluorescence intensity and so on.In this study,three-dimensional fluorescence technology was used to analyze the fluorescence spectrum characteristics of the wastewater from key industrial enterprises and urban domestic sewage in the urban section of an inland river in Xin jiang China.Typical industrial enterprises were selected to analyze the three-dimensional fluorescence of environmental factors,such as pH,heavy metal ions,solution concentration,etc.,on the DOM at the front and back ends(respectively representing high and low concentration organic polluted water)of wastewater treatment enterprises The influence rule of light spectral properties is as follows:1.The three-dimensional fluorescence technology was used to analyze the fluorescence spectrum characteristics of sewage from major industrial enterprises in an inland river city section in the Xinjiang.There are tryptophan-like peak T(Ex/Em=225-237/320-380nm and Ex/Em=275/320-380nm)in the untreated wastewater of all enterprises,Most of them have humus-like fluorescence peak A(Ex/Em=237～260/400～500nm,300～370)and peak C(Ex/Em=300～370/400～500 nm),Tyrosine-like peak B(Ex/Em=260-290/300-310nm and Ex/Em=275/310nm)were also detected in yeast products processing enterprises and dairy products enterprises;The DOM fluorescence peak and fluorescence intensity of the water body after the treatment of all enterprises decreased significantly,and the positions of the fluorescence peaks before and after the sewage treatment also changed.From the water intake to the aeration of the urban sewage treatment plant,the DOM in the water body is dominated by protein-like fluorescence peaks,and the effluent is dominated by humic acid-like fluorescence peaks.The peak T intensity increases after hydrolysis and acidification,COD,TN,NH3-N and TOC are positively correlated with the protein like fluorescence components in DOM,and the correlation coefficients are 0.891 7,0.8789,0.7513 and 0.6006,respectively.2.The fluorescence intensity of sewage before and after treatment by yeast product processing enterprises showed a downward trend with the increase of the dilution factor,and the degree of change was similar,and the position and number of fluorescence peaks did not change.With the increase of the dilution factor a(355),the change trend was consistent with the change in fluorescence intensity.It shows that the change of its concentration will not affect the type and number of fluorescence peaks,but only the fluorescence intensity.The experiments on the effects of different pH values on the fluorescence characteristics show that the intensity of each fluorescence peak reaches the maximum during the pH of 6-8,and then decreases with the increase of acidity and alkalinity.In addition,protein-like fluorescence peaks are affected by changes in pH,causing the fluorescence peak shift to be much greater than that of humic acid-like fluorescence peaks,indicating that protein-like peaks respond more strongly to changes in pH,and suggest that alkaline environments have a greater impact Large quenching effect.3.Different metal ions have similar quenching tendency to the fluorescence intensity of high-concentration organic wastewater,but the rate of intensity decrease is different.Among them,Cu2+has a greater intensity quenching rate for the peaks A and C,and Fe2+ has a higher tyrosine-like peak B The quenching rate is the largest.For the tryptophan-like peak T,the quenching rates of the three ions are comparable.Different metal ions have different quenching degrees of DOM fluorescence intensity in the influent water of yeast plant wastewater treatment.The same metal ions have different quenching degrees of different fluorescent components.Cu2+has a significant effect on the humus-like fluorescence intensity.Fe2+ The effect on protein-like fluorescence intensity is significant.With the increase of Cu2+ concentration,the A and C peaks exhibited red shifts to varying degrees.With the increase of Fe2+dosing concentration,the peak T showed repeated red and blue shifts;the peak C showed a red shift in both the excitation spectrum and the emission spectrum after the Fe2+ dosing concentration was 8mg/L.With the increase of Mn2+ concentration,the A-peak position shifted blue when the Mn2+ concentration was 1-5 mg/L,and the humus-like peak C red-shifted after the Mn2+ concentration was greater than 8 mg/L.4.The stern Volmer model is used to more clearly express the complexing effect of different metal ions on the fluorescence peaks of DOM,The results show that the quenching degree of T-peak fluorescence intensity of metal ions is the largest,which reflects the heterogeneity of complexation..For protein like fluorescence peak T,the complexation is from strong to if it is Fe2+>Cu2+>Mn2+,and for protein like fluorescence peak B,the complexation is from strong to if it is Fe2+>Mn2+>Cu2+.For the fluorescence peaks A and C of humic acid,the complexation is from strong to if they are Cu2+>Mn2+>Fe2+,which indicates that the complexation degree of different metal ions with the same fluorescence component in DOM is also different,reflecting the difference of different metal ions quenching the fluorescence intensity of dissolved organic matter. |
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