The Study On The Effect Of Chlorine Disinfection On The Production Of Photoactive Substances From Effluent Orgianic Matter

At present,the changes of morphology,structure and physicochemical properties of EfOM in water plant disinfection process need to be explored.,Humic acid and fulvic acid are important components of EfOM.Therefore,EfOM of Tangxun Lake Sewage Treatment Plant,humic acid and fulvic acid were selected as the research objects in this study.The effects of NaClO on their composition,structure and photochemical properties were investigated by means of spectral analysis and mass spectrometry.To study the influence of chlorine disinfection process on the structure and properties of EfOM can provide the necessary basic information for the photochemistry behavior and effect evaluation of EfOM after it enters the natural water environment.The main contents and conclusions of the experiment are as follows:The results of UV-Vis spectroscopy indicated that the aromaticity of EfOM,HA and FA decreased gradually,the molecular weight decreased and the degree of organic matter polymerization decreased with the increase of available chlorine.EfOM mainly contains humic acid-like substances,fulvic acid-like substances,and protein-like substances.The protein-like substances are mainly related to microbial metabolites,and the fluorescence peaks of protein-like proteins under chlorine disinfection are significantly reduced.When the chlorine disinfectant are added to humic substances,new fluorescent substances will gradually form over time,and the fluorescence peak will first decrease and then rise.Semi-quantitative analysis of the infrared absorption spectrum of the sample showed that the functional group change in EfOM was small as the dosage of NaClO increased.The infrared spectra of FA and HA have similar characteristic absorption peaks,which are more obvious with the increase of NaClO addition.The analysis changes may be related to the decomposition of stable structures into small molecules.The molecular weight of the sample was found to be found and the molecular weight of EfOM in the Tangshen Lake Wastewater Treatment Plant was small,and the increase in the effective chlorine dosage had no significant effect on the molecular weight of EfOM.The molecular weight changes of HA and FA samples were similar,and the changes were obvious under the action of NaClO,and the molecular weight became smaller and the distribution was uniform.The results of the effects of chlorine disinfection on the photoactive oxygen species of effluent organic matter show that:The ability of EfOM,FA and HA of the same TOC to produce singlet oxygen under simulated visible light conditions is FA>HA>EfOM.With the increase of available chlorine,EfOM does not show the change.The ability of FA and HA to generate singlet oxygen under different photocatalytic conditions is gradually enhanced.The ability to generate triplet is FA>HA>EfOM.With the increase of available chlorine,the formation of ~3EfOM~*does not show a significant change with the increase of chlorine content,and the formation of ~3FA~*and ~3HA~*is promoted.The ability to generate hydroxyl radicals is EfOM>FA>HA.With the increase of available chlorine,the ability of EfOM to generate hydroxyl radicals is inhibited,and the ability of FA and HA to generate hydroxyl radicals is enhanced.