Comprehensive evaluation method for pressure response of dissolved organic matters in sewage to far ultraviolet / peracetic acid disinfection

Abstract

The invention provides a comprehensive evaluation method for pressure response of dissolved organic matters in sewage to far ultraviolet / peracetic acid disinfection, which comprises the following steps: carrying out suction filtration on secondary effluent taken from a sewage plant by using a microfiltration membrane, and then adding peracetic acid to prepare mixed solutions of peracetic acid and water samples with different concentrations; carrying out far ultraviolet radiation on the mixed solution, and sampling in the disinfection process; the comprehensive evaluation method for the pressure response of the dissolved organic matters in the sewage to the far ultraviolet / peracetic acid disinfection comprises the following steps of: performing multi-dimensional analysis on an acquired sample. According to the method, the degradation characteristic, the molecular response characteristic and the influence on the disinfection system effect of the dissolved organic matters in the sewage in the far ultraviolet / peracetic acid combined disinfection process can be evaluated in a multi-dimensional manner, a scientific basis is provided for optimizing the sewage disinfection process through machine learning modeling, and accurate regulation and control of the disinfection process are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly to a comprehensive evaluation method for the pressure response of dissolved organic matter in sewage to far ultraviolet / peracetic acid disinfection. Background Art

[0002] With the acceleration of the urbanization process, the discharge of sewage is increasing continuously, and the types of pollutants contained therein are also becoming increasingly complex. These pollutants include not only organic and inorganic substances, but also pathogenic microorganisms such as bacteria, viruses, and parasites. The goal of urban sewage treatment is to remove or transform these pollutants, especially the removal of pathogenic microorganisms. In order to reduce the spread of these pathogenic microorganisms and ensure water quality safety, sewage disinfection has become an indispensable final link in the sewage treatment process.

[0003] Currently, common disinfection technologies include chlorine disinfection, ozone disinfection, ultraviolet disinfection, etc. Chlorine disinfection is economical, but may produce harmful disinfection by-products; ozone disinfection has strong bactericidal ability, but has high energy consumption and requires on-site preparation; ultraviolet disinfection has been widely used in recent years because it does not produce by-products and is easy to operate. Far-ultraviolet disinfection technology (Far-UVC) is a new type of ultraviolet disinfection method, and its wavelength range is between 200 and 230 nanometers. Compared with the traditional 254-nanometer ultraviolet light, the 222-nanometer far-ultraviolet light significantly reduces the harm to human skin and eyes, and no health hazards have been found in humans at effective disinfection doses. Traditional ultraviolet advanced oxidation technologies (such as using ultraviolet light with wavelengths of 254 nm, 265 nm, and 365 nm) have been widely used in the field of water treatment. However, compared with traditional ultraviolet advanced oxidation, far-ultraviolet advanced oxidation technology (usually referring to using ultraviolet light with a wavelength of 222 nm) generates higher photon energy, can effectively activate the oxidation process, and produces more oxidation active components, showing better effects in disinfection and water treatment. As a strong oxidant, peracetic acid mainly achieves disinfection by oxidizing the cell components of pathogenic microorganisms, and significantly fewer harmful by-products are generated during the disinfection process, and it has been increasingly valued in the application of sewage disinfection. With the entry of emerging pollutants into the water environment, the removal effect of traditional sewage disinfection technologies is limited, while far-ultraviolet / peracetic acid disinfection technology shows better potential in removing antibiotics and other refractory substances.

[0004] Dissolved organic matter in secondary effluent refers to the solvent-type organic substances released during the secondary treatment process of wastewater treatment plants. It mainly consists of three major components: one is natural organic matter (NOM), such as humic acid, etc.; the second is the products generated by microbial metabolism (SMPs, soluble microbial products); the third is synthetic organic substances that are difficult to degrade. The complexity of these components makes the properties and behaviors of dissolved organic matter have an important impact during the disinfection process. Wastewater disinfection not only changes the structural characteristics of dissolved organic matter but also affects its photochemical activity. After disinfection, the concentration of the oxidation-active components in dissolved organic matter may change, thereby affecting the disinfection mechanism and efficiency. For example, dissolved organic matter treated with low-concentration chlorine may promote the photodegradation of organic pollutants in water, while high-concentration chlorine treatment may inhibit this photodegradation effect. In summary, as an important component of water bodies, the transformation characteristics of dissolved organic matter during the disinfection process and its impact on the disinfection effect are worthy of in-depth study. However, the current research on the pressure response evaluation of dissolved organic matter in wastewater to far-ultraviolet / peracetic acid disinfection is still insufficient. Summary of the Invention

[0005] The present invention aims to provide a comprehensive evaluation method for the pressure response of dissolved organic matter in wastewater to far-ultraviolet / peracetic acid disinfection to solve the related problems existing in the prior art.

[0006] Specifically, the comprehensive evaluation method for the pressure response of dissolved organic matter in wastewater to far-ultraviolet / peracetic acid disinfection of the present invention includes the following steps: Step 1: Filter the secondary effluent taken from the wastewater treatment plant through a 0.45 μm microporous membrane by suction filtration, and then add peracetic acid (PAA), and prepare a mixed solution of different concentrations of peracetic acid + water sample; the method of the present invention first filters the secondary effluent from the wastewater treatment plant through a 0.45 μm microporous membrane to remove suspended particulate matter in the water, and the dissolved organic matter remains in the suction-filtered water sample. Step 2: Irradiate the mixed solution obtained in Step 1 with far-ultraviolet (UV 222 ) and take samples during the disinfection process. Step 3: Analyze the samples taken in Step 2 in multiple dimensions to evaluate the response characteristics of each dimension component.

[0007] Further, the concentrations of peracetic acid in the mixed solution prepared in Step 1 are 0 mg / L, 1 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, and 30 mg / L respectively; that is, six groups of filtered water samples are prepared and peracetic acid solutions are added respectively, so that the peracetic acid concentrations of these six groups of water sample + peracetic acid mixed solutions are 0 mg / L, 1 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, and 30 mg / L respectively.

[0008] Further, in Step 2, the power of the far-ultraviolet irradiation lamp is 20 W, and the irradiation duration is 0 - 60 minutes. Far-ultraviolet irradiation is carried out to analyze the pressure response mechanism of dissolved organic matter in multiple dimensions.

[0009] Further, the analysis dimensions in Step 3 include: S1 - UV analysis for UV 254 parameter determination and its three-dimensional fluorescence - parallel factor analysis, S2 - Fourier transform infrared spectroscopy combined with two-dimensional correlation spectroscopy analysis, S3 - gel permeation chromatography analysis, Fourier transform ion cyclotron resonance mass spectrometry analysis combined with machine learning, S4 - electron paramagnetic resonance analysis.

[0010] Further, S1 - UV analysis for UV 254 The specific steps of parameter determination and its three-dimensional fluorescence - parallel factor analysis are as follows: S11. Adjust the settings of the ultraviolet spectrophotometer to a wavelength of 254 nm, calibrate the instrument, place the water sample in a cuvette and measure its absorbance; for chemical oxygen demand, refer to the standard method of the Ministry of Ecology and Environment "HJ / T399 - 2007 Water Quality - Determination of Chemical Oxygen Demand - Fast Spectrophotometric Method". Take 2 mL of the test sample, heat it with sulfuric acid and the strong oxidant potassium dichromate at 165 °C for 20 minutes, let it stand to room temperature and then put it into a water quality detector for measurement.

[0011] S12. Set the excitation wavelength and emission wavelength, adjust the scanning speed and wavelength interval, then calibrate the instrument with a standard solution, perform excitation - emission scanning and record the data, and finally use parallel factor analysis to analyze the data and generate a three-dimensional fluorescence map of three fluorescence components. S13. Analyze and compare the changes in fluorescence intensities of the three fluorescence components in Step S12 during the far-ultraviolet / peracetic acid disinfection process.

[0012] Further, the excitation wavelength is 200 - 500 nm, and the emission wavelength is 200 - 600 nm.

[0013] Further, in the parallel factor analysis of step S12, the EEMCut function is used to cut the data to remove edge effects, and the OutlierTest function is used to detect and remove outliers; the effectiveness of the model is evaluated by EvalModel, and different factor models are compared using CompareSpecSSE; the data is split into three components and half-split verification is passed, and at the same time, three-dimensional fluorescence data is analyzed using ComponentEEM and ModelOut and the results are exported.

[0014] By comparing the chemical oxygen demand (COD, chemical oxygen demand) and the absorbance at 254 nm (UV 254 , ultraviolet absorption at 254 nm) indexes before and after disinfection of six disinfection systems, the removal effect of dissolved organic matter in far-ultraviolet / peracetic acid disinfection process is preliminarily evaluated, and the group with the best removal effect, that is, the group with a peracetic acid concentration of 30 mg / L, is selected for the next analysis; then, using three-dimensional fluorescence spectroscopy technology and combined with Matlab parallel factor analysis modeling, three fluorescence components of dissolved organic matter are extracted to determine the pressure response of the fluorescence components of dissolved organic matter.

[0015] Three-dimensional fluorescence-parallel factor analysis mainly decomposes the fluorescence data into multiple potential factors (i.e., the fluorescence components of the sample) using the parallel factor model according to the three-dimensional fluorescence data of the collected samples, extracts the excitation spectrum, emission spectrum and relative fluorescence intensity of each factor through an optimization algorithm, and evaluates the response of dissolved organic matter to far-ultraviolet / peracetic acid disinfection according to the change of fluorescence intensity during the disinfection process.

[0016] Further, the steps of Fourier transform infrared spectroscopy combined with two-dimensional correlation spectroscopy in S2 are as follows: S21. Collect the infrared spectral data of the sample through Fourier transform infrared spectroscopy technology and organize these data into a three-dimensional data matrix; S22. Perform two-dimensional Fourier transform on the matrix data in step S21 to generate two-dimensional correlation synchronous spectra and asynchronous spectra, so as to reveal the cooperative changes and temporal differences of the functional groups of the substance and evaluate the dynamic response of the substance structure in the far-ultraviolet / peracetic acid disinfection process.

[0017] Identify the dynamic response of the functional groups of dissolved organic matter during disinfection through Fourier transform infrared spectroscopy, and combine two-dimensional correlation spectroscopy technology to further reveal the reaction order of different functional groups.

[0018] Further, the specific steps of S3 - gel permeation chromatography analysis, Fourier transform ion cyclotron resonance mass spectrometry analysis and machine learning are as follows: S31. Pass the sample solution through a chromatographic column filled with porous gel, separate according to the penetration degree of molecules in the pores based on different molecular sizes, and thus estimate the relative molecular weight of the substance by detecting the time when different molecules flow out of the column; S32. After detecting the samples obtained during the far ultraviolet / peracetic acid disinfection process, use known hydrocarbon-oxygen (CHO) compounds in dissolved organic matter for internal standard calibration. After calibration, perform molecular formula matching on the mass spectrometry data according to the standard of S / N > 4. The screening conditions include retaining the hydrogen-carbon ratio (H / C, hydrogen-to-carbon ratio) and oxygen-carbon ratio (O / C, oxygen-to-carbon ratio) within a specific range, and screen the eligible molecular formulas according to the deoxygenated double bond equivalent value (DBE-O, double bond equivalent minus oxygen); S33. Analyze the detected mass spectrometry peaks (100 - 800 Da), and the results include the molecular formula and the corresponding molecular composition; S34. Divide the data of Fourier transform ion cyclotron resonance mass spectrometry analysis into a training set and a test set, use grid search for hyperparameter tuning of the XGBoost model, train the final model and make predictions, use the Shapley Additive exPlanation (SHAP) for feature importance analysis, and visualize the results through a Sankey diagram, so as to evaluate the influence of the molecular characteristics of substances on the molecular reaction characteristics during the far ultraviolet / peracetic acid disinfection process.

[0019] The molecules of dissolved organic matter in the secondary effluent are mainly concentrated in the range of 300 - 500 Da. During the far ultraviolet / peracetic acid disinfection process, the molecules of dissolved organic matter transform towards high H / C and high O / C, from a low saturation state, high aromaticity and low oxidation state to a high saturation state, low aromaticity and low oxidation state. Among them, the molecular weight and O / C are the characteristic parameters that have the greatest influence on the molecular reactivity.

[0020] Combined with Fourier transform ion cyclotron resonance mass spectrometry and gel permeation chromatography, evaluate the molecular weight distribution characteristics of dissolved organic matter at four time points during the disinfection process. Based on the mass spectrometry data, deeply analyze the changes in the molecular characteristics of dissolved organic matter during the disinfection process, including the carbon-hydrogen ratio, carbon-oxygen ratio, deoxygenated double bond equivalent to carbon ratio ((DBE-O) / C, double bond equivalent minus oxygen per carbon), and modified aromaticity index (AI mod, important parameters such as the modified aromaticity index, the nominal oxidation state of carbon (NOSC), and the number of various atoms were obtained. It was found that as disinfection proceeded, the H / C ratio and O / C ratio of dissolved organic matter molecules showed an increasing trend. Based on these data and combined with machine learning methods, it was further determined that the oxygen-carbon ratio and molecular weight are important parameters affecting the reactivity of dissolved organic matter molecules, thereby revealing the potential influence of molecular structure on transformation characteristics and reaction behavior; to further evaluate the effect of dissolved organic matter on far ultraviolet / peracetic acid disinfection.

[0021] Furthermore, the specific steps of S4 - electron paramagnetic resonance analysis are as follows: S41. Select a suitable electron spin trap and add it to the water sample + far ultraviolet / peracetic acid system and deionized water + far ultraviolet / peracetic acid system; S42. Use electron paramagnetic resonance technology to detect the spectral signals of the capturer adducts in the samples collected from the water sample + far ultraviolet / peracetic acid system and deionized water + far ultraviolet / peracetic acid system respectively, and analyze their characteristic heterodyne signals to determine the types and relative concentrations of oxidative active species.

[0022] Furthermore, the electron spin trap is selected from one of 5 - (diisopropoxyphosphoryl) - 5 - methyl - 1 - pyrroline N - oxide (DIPPMPO, 5 - diisopropoxyphosphoryl - 5 - methyl - 1 - pyrroline - N - oxide), 5,5 - dimethyl - 1 - pyrroline - N - oxide (DMPO, 5,5 - Dimethyl - 1 - pyrroline - N - oxide), and 2,2,6,6 - tetramethylpiperidine (TEMP, 2,2,6,6 - tetramethyl - 4 - piperidinol).

[0023] DIPPMPO is mainly used to capture methyl radicals (·CH3), DMPO is used to identify hydroxyl radicals (·OH), while TEMP is used to capture singlet oxygen ( 1 O2).

[0024] Use electron paramagnetic resonance to detect hydroxyl radicals (·OH), methyl radicals (·CH3), and singlet oxygen ( 1Identify and analyze oxidation - active species such as O2), etc., so as to determine that the presence of dissolved organic matter can promote the generation of oxidation - active species in the system; finally, with the help of multivariate correlation network heat - map analysis, comprehensively evaluate the degradation characteristics, molecular characteristics, fluorescence component response of dissolved organic matter in sewage during far - ultraviolet / peracetic acid disinfection, and its associated impact on the generation of oxidation - active species.

[0025] Compared with the prior art, the present invention has the following outstanding features and advantages: 1. The comprehensive evaluation method adopted by the present invention analyzes the degradation characteristics, fluorescence characteristics, molecular characteristics changes of dissolved organic matter and its impact on the generation of oxidation - active species through multiple dimensions, so as to provide data support and theoretical basis for optimizing the disinfection effect, and help to improve the disinfection efficiency and safety in the sewage treatment process.

[0026] 2. The comprehensive evaluation method for the pressure response of dissolved organic matter in sewage to far - ultraviolet / peracetic acid disinfection of the present invention is applicable to multi - dimensional evaluation of the pressure response of dissolved organic matter under far - ultraviolet / peracetic acid disinfection. In addition, the combined disinfection of peracetic acid and far - ultraviolet light has significant advantages in practical applications, including high - efficient bactericidal ability, synergistic effect, wide applicability, and reduced risk of drug resistance. This combined disinfection technology is not only environmentally friendly and low - cost, but also can improve the disinfection efficiency, reduce the chemical dosage and ultraviolet irradiation intensity, and reduce the resistance problem. The combination of the two can also reduce the operation and maintenance costs, providing an economical and efficient disinfection solution.

[0027] 3. The comprehensive evaluation method for the pressure response of dissolved organic matter in sewage to far - ultraviolet / peracetic acid disinfection of the present invention can comprehensively evaluate the degradation characteristics and molecular structure changes of dissolved organic matter during far - ultraviolet / peracetic acid disinfection through multi - dimensional analysis methods, including ultraviolet analysis, three - dimensional fluorescence spectroscopy, Fourier transform infrared spectroscopy, mass spectrometry, etc. The results show that the dissolved organic matter in secondary effluent shows an obvious degradation trend during far - ultraviolet / peracetic acid disinfection. When the concentration of peracetic acid is 30 mg / L, the chemical oxygen demand removal rate is 64%, UV 254 removal rate is 39.22%, and the fluorescence intensity response decreases by 66.09%; during far - ultraviolet / peracetic acid disinfection, the molecules of dissolved organic matter transform towards high H / C and high O / C, from low saturation, high aromaticity and low oxidation state to high saturation, low aromaticity and high oxidation state; by deeply analyzing the changes in the molecular characteristics of dissolved organic matter and combining machine learning for data modeling, key molecular features affecting disinfection reactivity such as molecular weight and O / C can be effectively identified, providing clear parameter guidance for further optimizing the sewage disinfection process.

[0028] 4. The comprehensive evaluation method for the pressure response of dissolved organic matter in sewage to far-ultraviolet / peracetic acid disinfection in the present invention reveals that the presence of dissolved organic matter can promote the generation of oxidative active species in the system, especially the influence on species such as ·OH, ·CH3, and 1 O2, etc., provides a scientific basis for further optimizing the far-ultraviolet / peracetic acid combined disinfection process, and improves the disinfection efficiency and safety in the sewage treatment process. Description of the Drawings

[0029] Figure 1 (a) Absorbance at 254 nm (UV 254 , ultraviolet absorption at 254 nm) and (b) chemical oxygen demand (COD, chemical oxygen demand) concentration and its removal rate variation diagrams at six peracetic acid concentrations in the examples; Figure 2 Three fluorescence components screened by fitting the fluorescence component data of dissolved organic matter during far-ultraviolet / peracetic acid disinfection using the parallel factor method in the examples (where (a), (c), and (e) are the fluorescence responses of component one, component two, and component three respectively (Region I: Aromatic protein I, Region II: Aromatic protein II, Region III: Fulvic acid-like substances, Region IV: Soluble microbial metabolite-like substances, Region V: Humic acid-like substances), and (b), (d), and (f) are the fluorescence loads of component one, component two, and component three respectively); Figure 3 Variation diagrams of the maximum fluorescence intensity (Maximum Fluorescence Intensity) of three fluorescence components, namely component one (Component 1), component two (Component 2), and component three (Component 3) during far-ultraviolet / peracetic acid disinfection in the examples; Figure 4 Changes and response sequences of functional groups of dissolved organic matter during far-ultraviolet / peracetic acid disinfection identified by Fourier transform infrared spectroscopy combined with two-dimensional correlation spectroscopy in the examples ((a) Two-dimensional correlation synchronous spectrogram, (b) Two-dimensional correlation asynchronous spectrogram); Figure 5 Abundance curves of dissolved organic matter molecules at (a) 0 min, (b) 15 min, (c) 30 min, and (d) 60 min during far-ultraviolet / peracetic acid disinfection in the examples; Figure 6 Molecular weight distribution of dissolved organic matter analyzed by gel permeation chromatography during far-ultraviolet / peracetic acid disinfection in the examples; Figure 7V-K marginal density plots of unique molecular formula distributions during far-UV / peracetic acid disinfection in the examples (A: aliphatic / protein, B: lipids, C: lignin / CRAM-like structures, D: unsaturated hydrocarbons, E: carbohydrates, F: aromatic structures, and G: tannic acid); Figure 8 For the dissolved organic matter during far-UV / peracetic acid disinfection in the examples, (a) the ratio of deoxygenated double bond equivalent to carbon number ((DBE-O) / C, double bond equivalent minus oxygen per carbon), (b) the modified aromaticity index (AI mod , modified aromaticity index), and (c) the nominal oxidation state of carbon (NOSC) changes; Figure 9 For the dissolved organic matter during far-UV / peracetic acid disinfection in the examples, waterfall plots of the feature importance of Shapley Additive exPlanation (SHAP) values for (a) 0 - 15 min, (b) 15 - 30 min, and (c) 30 - 60 min; Figure 10 For the comprehensive Shapley Additive exPlanation (SHAP) feature analysis of molecular characteristics during far-UV / peracetic acid disinfection in the examples ((a) the relationship between oxygen-to-carbon ratio (O:C) and molecular weight (MW), (b) the relationship between molecular weight (MW) and the number of nitrogen atoms (nN), (c) the relationship between the number of nitrogen atoms (nN) and oxygen-to-carbon ratio (O:C)); Figure 11 For the Sankey diagram of the contribution of molecular Shapley Additive exPlanation (SHAP) feature values based on normalized molecular properties to molecular reactivity during far-UV / peracetic acid disinfection in the examples; Figure 12For the electron paramagnetic resonance spectra of hydroxyl radicals (·OH) using (a) 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) during the far-ultraviolet / peracetic acid disinfection process in the example, methyl radicals (·CH3) using (b) 5-(diisopropoxyphosphoryl)-5-methyl-1-pyrroline N-oxide (DIPPMPO), and singlet oxygen ( 1 O2) using (c) 2,2,6,6-tetramethylpiperidine (TEMP) in the example; Figure 13 For the correlation heatmap between the composition of substances in dissolved organic matter analyzed by three-dimensional fluorescence-parallel factor analysis and Fourier transform ion cyclotron resonance mass spectrometry and reactive oxygen species during the far-ultraviolet / peracetic acid disinfection process in the example (*, **, and *** indicate significant correlations, i.e., P < 0.05, P < 0.01, and P < 0.001). Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. The technical solutions of the present invention will be further described below in conjunction with implementation cases.

[0031] Embodiment This embodiment provides a comprehensive evaluation method for the pressure response of dissolved organic matter in sewage to far-ultraviolet / peracetic acid disinfection, including the following steps: Step S1. The water sample is from the secondary effluent of a sewage treatment plant in Jiading District, Shanghai. The sewage treatment plant adopts the anaerobic-anoxic-oxic (AAO) process. The water sample is taken from the secondary effluent treated by the AAO process. First, the water sample is shaken well to prevent sediment accumulation at the bottom, and then filtered through a 0.45 μm microporous filter membrane and stored at 4 °C. Then, six groups of 250 mL filtered water samples are prepared. In these six groups of filtered water samples, peracetic acid solutions are added respectively so that the peracetic acid concentrations in these six mixed solution systems are 0 mg / L, 1 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, and 30 mg / L respectively.

[0032] Step S2. Conduct far-ultraviolet irradiation experiments on six groups of mixed solutions. The power of the far-ultraviolet lamp used is 20 W, the total irradiation duration is 1 hour, the distance between the light source and the liquid surface is 10 cm, and samples are taken at 0 min, 1 min, 3 min, 5 min, 10 min, 15 min, 20 min, 30 min, 45 min, and 60 min during the irradiation process. Finally, multi-dimensional analysis and evaluation are performed on the samples. Step S3. Retrieve the chemical oxygen demand (COD, chemical oxygen demand) and the absorbance at 254 nm (UV 254 , ultraviolet absorption at 254 nm) of the water samples taken in Step S2, and compare the degradation of dissolved organic matter during the far-ultraviolet / peracetic acid disinfection process at different peracetic acid concentrations. It mainly includes the following steps: Step S31. For the chemical oxygen demand, refer to the standard method of the Ministry of Ecology and Environment, "HJ / T399-2007 Determination of Chemical Oxygen Demand in Water Quality - Fast Spectrophotometry Method". Take 2 mL of the sample and place it in a test tube with pre-prepared reagents. Heat it with sulfuric acid and the strong oxidant potassium dichromate at 165 °C for 20 min, and let it stand until room temperature. First, place a blank sample (deionized water) in the COD rapid detector and perform a zeroing operation according to the zero adjustment. Then, officially place the test sample tube and directly read the COD concentration according to the reading.

[0033] Step S32. Turn on the ultraviolet spectrophotometer, select a wavelength of 254 nm, use deionized water as the blank sample, add it to the cuvette of the photometer, ensure that the light path is clear, and perform zero calibration. Then, add the water sample to be tested to the cuvette and place it in the sample compartment of the photometer to read the absorbance value.

[0034] As Figure 1 shown, in the six groups of mixed solutions, as the concentration of added peracetic acid increases, the removal rates of UV 254 ( Figure 1 (a)) and COD ( Figure 1 (b)) of the dissolved organic matter in the system increase. When the concentration of peracetic acid in the system reaches 30 mg / L, the removal rates of UV 254 and COD of the dissolved organic matter in the system are the largest, which are 39.22% and 66.09% respectively. Therefore, in the following dimensional analysis, samples with a peracetic acid concentration of 30 mg / L are used.

[0035] Step S4. Use a Cary Eclipse fluorescence spectrometer (F7100, Shimadzu, Japan), set the scanning speed to 4800 nm / min, the excitation wavelength to 200 - 500 nm with an interval of 10 nm, and the emission wavelength to 200 - 600 nm with an interval of 10 nm. First, put deionized water in a cuvette to zero the instrument. Then, take 3 mL of the sample to be tested with a peracetic acid concentration of 30 mg / L and put it into the cuvette. Wipe the surface of the cuvette with lens paper, and then place the cuvette into the sample chamber and start the instrument for data acquisition; collect two sets of parallel samples at 0 min, 1 min, 3 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 40 min, 50 min, and 60 min during the far - ultraviolet / peracetic acid disinfection process, a total of 24 samples, and perform parallel factor analysis using the matlab toolbox (DOMFluor). The parallel factor analysis steps in Step S4 include the following steps: Step S41. Prepare the three - dimensional fluorescence data and organize it into a three - dimensional array, and then create a structure to store the excitation spectrum, emission spectrum, and sample data; Step S42. Use the EEMCut function to cut the data to remove edge effects, and use the OutlierTest function to detect and remove outliers; Step S43. Evaluate the effectiveness of the model through EvalModel, and use CompareSpecSSE to compare the performance of different factor models, and finally select the three - component model; Step S44. Perform three - component splitting and half - split verification on the data. At the same time, analyze the three - dimensional fluorescence data using ComponentEEM and ModelOut and export the results.

[0036] Step S45. Compare the results exported in Step S44 to evaluate the fluorescence intensity response of the fluorescent components during the far - ultraviolet / peracetic acid disinfection process.

[0037] Step S5. Freeze - dry the samples at 0 min, 15 min, 30 min, and 60 min in Step S2 to ensure that the samples are uniform and suitable for Fourier transform infrared spectroscopy analysis; use a Fourier transform infrared spectrometer (Thermo Fisher Scientific Nicolet iS5, USA), set the scanning wavelength range to 800 - 4000 cm -1, with a resolution of 4.000, the sample was scanned 32 times, and spectral acquisition was carried out; the two-dimensional correlation spectroscopy was plotted for the collected Fourier transform infrared spectroscopy data using origin software, and the relative positions and intensities of the peaks in the synchronous spectrum and asynchronous spectrum plotted were analyzed to obtain information on intermolecular interactions and dynamic changes.

[0038] Step S6. Appropriately dilute the samples with a peracetic acid concentration of 30 mg / L at 0 min, 15 min, 30 min, and 60 min in Step S2. The samples need to be bottled for easy operation, and the prepared samples are directly injected into a gel permeation chromatograph (Agilent PL-GPC50, USA). Calculate the molecular weight and fractionation distribution of the samples based on the retention time and calibration curve.

[0039] Step S7. Use a Fourier transform ion cyclotron resonance mass spectrometer (Solarix 15T, Bruker Technology Co., Ltd., USA) for the samples with a peracetic acid concentration of 30 mg / L at 0 min, 15 min, 30 min, and 60 min in Step S2. Take 200 μL of the sample and directly inject it for mass spectrometry analysis. The ion source is an electrospray ionization source (ESI), in negative ion detection mode. The mass spectrometry data is calibrated with known carbon, hydrogen, and oxygen (CHO) compounds as internal standards, and the molecular formula matching is carried out according to the set elemental composition (such as carbon, hydrogen, oxygen, nitrogen, sulfur). The screening conditions include: the retention hydrogen-carbon ratio (H / C) is between 0.2 and 2.3, the oxygen-carbon ratio (O / C) is between 0 and 1.2, and the deoxygenated double bond equivalent (DBE-O) value ranges from -10 to 10. If an m / z value corresponds to multiple molecular formulas, select the molecular formula with the fewest heteroatoms. If there are still multiple choices, retain the molecular formula with the smallest error value as the correct answer. Analyze the mass spectrometry peaks in the m / z value range of 100 - 800 Da to obtain the accurate molecular composition and generate relevant result data.

[0040] Step S9. Divide the mass spectrometry data obtained in Step S7 into a training set and a test set, load the necessary R packages, import and preprocess the training and test data, perform hyperparameter grid search to optimize the model, train the final model and make predictions on the test set. Finally, evaluate the model performance using a confusion matrix, calculate the Shapley additive explanation value (SHAP) for model interpretation, and visualize the feature importance using a Sankey diagram.

[0041] Step S9. Set up a deionized water + far ultraviolet / peracetic acid disinfection system and a water sample + far ultraviolet / peracetic acid disinfection system, and analyze the oxidative active species in the two systems respectively. The steps are as follows: Step S91. Add appropriate amounts of peracetic acid to deionized water and the water sample respectively to ensure that the concentration of peracetic acid in both systems is 30 mg / L. Irradiate for 60 min using a far-ultraviolet lamp with the light source 10 cm away from the sample surface; Step S92. Use 5-(diisopropoxyphosphoryl)-5-methyl-1-pyrroline N-oxide (DIPPMPO) to capture methyl radicals (·CH3), use 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) to capture hydroxyl radicals (·OH), and use 2,2,6,6-tetramethylpiperidine (TEMP) to capture singlet oxygen ( 1 ¹O2); Step S93. Quickly take samples at the beginning and end of the disinfection reaction. Immediately mix the sampled liquid with the selected capture agent, place the prepared sample in the sample chamber for measurement, and record the electron paramagnetic resonance magnetic field intensity signal; Step S94. Analyze the obtained electron paramagnetic resonance magnetic field and intensity data to identify the characteristic signals of hydroxyl radicals (·OH), singlet oxygen ( 1 ¹O2), and methyl radicals (·CH3).

[0042] As Figure 2 shown, after far-ultraviolet irradiation of the mixed solution of 30 mg / L peracetic acid + water sample, three-dimensional fluorescence-parallel factor analysis was carried out, and it was found that the dissolved organic matter was three fluorescence components (Region I: Aromatic protein I, Region II: Aromatic protein II, Region III: Fulvic acid-like substances, Region IV: Soluble microbial metabolite-like substances, Region V: Humic acid-like substances), namely fulvic acid-like substances, aromatic proteins, and humic acid-like substances.

[0043] Figure 3 Shows the changes in fluorescence components and their maximum fluorescence intensities during far-ultraviolet / peracetic acid disinfection. As shown by the results, the maximum fluorescence intensity responses of the three fluorescence components gradually decreased during far-ultraviolet / peracetic acid disinfection. Specifically, the maximum fluorescence intensities of fulvic acid-like substances (Component I), aromatic proteins (Component II), and humic acid-like substances (Component III) decreased by 64.49%, 74.74%, and 56.19% respectively after disinfection.

[0044] As Figure 4 shown, after far-ultraviolet irradiation of the mixed solution of 30 mg / L peracetic acid + water sample, Fourier transform infrared two-dimensional correlation spectroscopy analysis was carried out. From the two-dimensional correlation synchronous spectrum ( Figure 4 (a)), it can be seen that 1056 cm - ⁻¹, 1231 cm - ⁻¹ are related to C-O stretching vibrations, and 1335 cm -¹ is related to C-N stretching vibration, 1384 cm - ¹ is related to C-H stretching vibration, 1497 cm - ¹ is related to C-C stretching vibration of the aromatic ring, 1547 cm - ¹ is related to C=C stretching vibration of the aromatic ring, 1635 cm - ¹ is related to C=C double bond stretching vibration, 3436 cm - ¹ is related to O-H stretching vibration. From the two-dimensional correlation asynchronous spectrogram ( Figure 4 (b)), the reaction order is determined as: C-O stretching vibration, C-N stretching vibration, C-C stretching vibration of the aromatic ring, C-H stretching vibration, C=C double bond stretching vibration, C=C stretching vibration of the aromatic ring, O-H stretching vibration. Through Fourier transform infrared two-dimensional correlation spectroscopy analysis, the response characteristics of different functional groups during the reaction can be clarified, revealing the reaction sequence and mechanism of peracetic acid with organic substances in the water sample. The appearance of C-O and C-N stretching vibrations first indicates that peracetic acid has a strong influence on the functional groups in the water sample, while the changes in the aromatic ring and C–H, C=C double bonds reflect the gradual modification and degradation of the organic substance structure during the reaction. Finally, the change in O-H stretching vibration indicates the completion of the oxidation process or hydration.

[0045] As Figure 5 shown, the total relative intensities of molecules with different molecular weights in the mixed solution of 30 mg / L peracetic acid + water sample during far-ultraviolet disinfection process at (a) 0 min, (b) 15 min, (c) 30 min, and (d) 60 min were analyzed. The molecular abundances at different time points are marked with different colors, highlighting the changes in molecular weight during disinfection. The color of the scatter points is related to their proportion in the sample, as shown in the color scale. It can be seen that the molecular weight distribution in the sample is relatively concentrated, mainly distributed in the range of 300 - 500 Da, and the overall change trend is not obvious.

[0046] Figure 6 This is the result of gel permeation chromatography analysis. This result further confirms that in the far-ultraviolet / peracetic acid disinfection system, the molecular weight distribution of dissolved organic matter is concentrated, mainly distributed in the range of 300 - 500 Da, and the overall change trend is not obvious.

[0047] Figure 7 、 Figure 8 This is the analysis result of Fourier transform ion cyclotron resonance mass spectrometry data. As Figure 7 shown, the transformation of dissolved organic matter molecules during far-ultraviolet / peracetic acid disinfection process tends to be towards higher oxygen-carbon ratio and higher hydrogen-carbon ratio; Figure 8The ratio of deoxygenated double bond equivalent to carbon number ((DBE-O) / C) shown in (a) can characterize the relationship between the degree of unsaturation and oxygen content of a molecule. A higher (DBE-O) / C value generally indicates that the molecule has more double bonds, aromatic rings or unsaturated structures and may contain fewer oxygen atoms. It can be seen that the (DBE-O) / C value of dissolved organic matter molecules becomes smaller during far-UV / peracetic acid disinfection, which means that its molecules tend to be more saturated and may contain more oxygen atoms. Figure 8 The modified aromaticity index (AI mod ) shown in (b) is an index used to characterize the aromaticity of a molecule. A higher AI mod value indicates that the molecule has stronger aromaticity. Here, it can be seen that the AI mod value of dissolved organic matter molecules decreases during disinfection, which means that aromatic substances are gradually removed. Figure 8 The nominal oxidation state of carbon (NOSC) value shown in (c) is a quantitative index used to characterize the oxidation state of carbon elements in a molecule. The calculation formula is: NOSC = 4−(H / C + 2O / C + N / C + P / C + S / C). A higher NOSC value indicates that the carbon atoms in the molecule tend to be in a higher oxidation state. The results show that the NOSC value of dissolved organic matter molecules increases during disinfection, and an oxidation reaction occurs in the system. The overall results of Fourier transform ion cyclotron resonance mass spectrometry data analysis show that dissolved organic matter undergoes an oxidation reaction during far-UV / peracetic acid disinfection, and its molecules tend to be saturated and oxidized. Generally speaking, dissolved organic matter undergoes oxidation degradation, dearomatization and saturation changes during far-UV / peracetic acid disinfection. The oxygen content of the molecules increases and the unsaturated structures decrease, showing obvious oxidation reaction characteristics. These changes are the direct result of the treatment of dissolved organic matter during disinfection, indicating that its molecular structure becomes simpler and richer in oxygen elements.

[0048] Figure 9 、 Figure 10 and Figure 11 are the contribution of SHAP feature values of molecular properties predicted by a machine learning model based on Fourier transform ion cyclotron resonance mass spectrometry data to molecular reactivity. Figure 9(a), (b), and (c) respectively show the influence of each molecular property on the reaction property during the 0 - 15 min, 15 - 30 min, and 30 - 60 min stages of disinfection. It can be seen that molecules with a lower oxygen - carbon ratio are more easily removed to form molecules with a higher oxygen - carbon ratio. This may be because a large number of oxidative reactive species are generated during the far - ultraviolet / peracetic acid disinfection process, resulting in the oxidation reaction and removal transformation of dissolved organic matter. The molecular weight appears in multiple sub - figures. Although its SHAP value fluctuates slightly, generally, the degree of influence on molecular reactivity is relatively stable. Figure 10 (a), (b), and (c) respectively show the combined influence of molecular weight, oxygen - carbon ratio, and number of nitrogen atoms on molecular reactivity pairwise during the 0 - 15 min, 15 - 30 min, and 30 - 60 min stages of disinfection. It can be seen that in all categories (removal, unchanged, generation), there is a strong relationship between molecular weight and oxygen - carbon ratio, especially when the SHAP value is relatively high. This indicates that the oxygen - carbon ratio has a greater influence on molecular reaction; while the distribution of SHAP values of the number of nitrogen atoms is relatively uniform in each category and the influence is smaller. Especially in the removal and unchanged categories, the influence of the number of nitrogen atoms on molecular reactivity is smaller. Figure 11 The Sankey diagram also further shows that the oxygen - carbon ratio is the most important characteristic parameter affecting molecular reactivity. The oxygen - carbon ratio is the most important reactivity characteristic during the disinfection process. Molecules with a low oxygen - carbon ratio tend to be removed, while molecules with a high oxygen - carbon ratio are generated during the reaction, indicating that the oxidation reaction is the main reaction mechanism during the disinfection process.

[0049] Figure 12 Electron paramagnetic resonance spectra of (a) 5,5 - dimethyl - 1 - pyrroline - N - oxide (DMPO) for hydroxyl radical (·OH), (b) 5 - (diisopropoxyphosphoryl) - 5 - methyl - 1 - pyrroline N - oxide (DIPPMPO) for methyl radical (·CH3), and (c) 2,2,6,6 - tetramethylpiperidine (TEMP) for singlet oxygen ( 1 1O2) during the far - ultraviolet / peracetic acid disinfection process. Deionized water is blue and secondary effluent is red. It can be seen that in the presence of dissolved organic matter, the signals of hydroxyl radical (·OH), methyl radical (·CH3), and singlet oxygen ( 1 1O2) in the system are stronger, which also indicates that the presence of dissolved organic matter can promote the generation of oxidative reactive species during the far - ultraviolet / peracetic acid disinfection process.

[0050] Figure 13Heatmap showing the correlation between the composition of substances in solvent organic matter analyzed by three-dimensional fluorescence - parallel factor analysis and Fourier transform ion cyclotron resonance mass spectrometry and reactive oxygen species during far - ultraviolet / peracetic acid disinfection (*, **, and *** indicate significant correlations, P < 0.05, P < 0.01, and P < 0.001). It can be seen that there is a significant positive correlation between COD, UV 254 and the three fluorescence components. These three indicators all characterize the high degradability of dissolved organic matter during far - ultraviolet / peracetic acid disinfection; the number of oxygen atoms and the oxygen - to - carbon ratio are significantly negatively correlated with the fluorescence components, indicating that during far - ultraviolet / peracetic acid disinfection, the degradation of dissolved organic matter tends to transform into a higher oxidation state.

[0051] The above - mentioned embodiments obtain the following beneficial effects compared with the prior art: The method for evaluating the response of dissolved organic matter in sewage to far - ultraviolet / peracetic acid combined disinfection pressure of the present invention aims to analyze and evaluate the degradation characteristics, molecular structure changes of dissolved organic matter during far - ultraviolet / peracetic acid disinfection, and its impact on the generation of oxidative active species during disinfection in multiple dimensions. This method combines technologies such as ultraviolet analysis, three - dimensional fluorescence spectroscopy, Fourier transform infrared spectroscopy, and mass spectrometry analysis to comprehensively evaluate the chemical changes during disinfection. The experimental results show that dissolved organic matter exhibits a significant degradation trend during far - ultraviolet / peracetic acid combined disinfection. When the concentration of peracetic acid is 30 mg / L, the COD removal rate reaches 64%, UV 254 removal rate is 39.22%, and the fluorescence intensity response decreases by 66.09%. At the same time, the molecular structure changes indicate that the molecules of dissolved organic matter transform from low saturation, high aromaticity, and low oxidation state to high saturation, low aromaticity, and low oxidation state. In addition, by combining machine learning for data modeling, key molecular characteristics affecting disinfection reactivity, such as molecular weight, oxygen - to - carbon ratio, and number of nitrogen atoms, can be identified, thereby providing effective parameter guidance for further optimizing the sewage disinfection process. The combined disinfection technology (far - ultraviolet + peracetic acid) of the present invention has significant advantages: high bactericidal ability, synergistic effect, wide applicability, and can reduce the risk of drug resistance. This method is not only environmentally friendly and low - cost, but also can improve the disinfection efficiency, reduce the chemical dosage and ultraviolet irradiation intensity, and lower the operation and maintenance costs. By deeply analyzing the molecular changes of dissolved organic matter during disinfection, the present invention provides a scientific basis for optimizing the far - ultraviolet / peracetic acid combined disinfection process, and improves the disinfection efficiency and safety during the sewage treatment process.

[0052] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made on their own, and these all fall within the protection scope of the present invention.

Claims

1. A comprehensive evaluation method for the pressure response of dissolved organic matter in sewage to far ultraviolet / peracetic acid disinfection, characterized in that, The following steps are involved: Step 1: Filter the secondary effluent from the sewage treatment plant using a microporous filter membrane, then add peracetic acid to prepare a mixed solution of peracetic acid + water sample with different concentrations; Step 2: subjecting the mixed solution obtained in step 1 to far ultraviolet irradiation, and taking samples during the disinfection process; Step 3: Conduct a multi-dimensional analysis on the samples taken in step 2 to evaluate the response characteristics of the components in each dimension.

2. The method according to claim 1, characterized in that, The concentrations of peracetic acid in the mixed solutions prepared in step 1 are 0 mg / L, 1 mg / L, 5 mg / L, 10 mg / L, 20 mg / L and 30 mg / L, respectively.

3. The method according to claim 1, characterized in that, In step 2, the power of the far-ultraviolet irradiation lamp is 20 W, and the irradiation time is 0-60 minutes.

4. The method according to claim 1, wherein In step 3, the analysis dimensions include: S1 - UV analysis for UV 254 parameter determination and its three-dimensional fluorescence - parallel factor analysis, S2 - Fourier transform infrared spectroscopy combined with two-dimensional correlation spectroscopy analysis, S3 - gel permeation chromatography analysis, Fourier transform ion cyclotron resonance mass spectrometry analysis combined with machine learning, S4 - electron paramagnetic resonance analysis.

5. The method according to claim 4, wherein S1 - UV analysis for ultraviolet 254 The specific steps for parameter determination and its three - dimensional fluorescence - parallel factor analysis are as follows: S11. Adjust the UV spectrophotometer to 254 nm wavelength, calibrate the instrument, place the sample in a cuvette and measure its absorbance; S12, setting the excitation wavelength and emission wavelength, and adjusting the scanning speed and wavelength interval, then calibrating the instrument using a standard solution, performing an excitation-emission scan and recording data, and finally analyzing the data using parallel factor analysis and generating a three-dimensional fluorescence map of the three fluorescent components; S13, analyzing and comparing the changes in fluorescence intensity of the three fluorescent components in step S12 during the far-ultraviolet / peracetic acid disinfection process.

6. The method according to claim 5, characterized in that The excitation wavelength is 200-500 nm, and the emission wavelength is 200-600 nm.

7. The method according to claim 5, wherein In step S12, the EEMCut function was used to cut the data to remove edge effects in the parallel factor analysis, and the OutlierTest function was used to detect and remove outliers. The effectiveness of the model was evaluated by EvalModel, and the performance of different factor models was compared using CompareSpecSSE. The data was split into three components and half-split for verification. At the same time, ComponentEEM and ModelOut were used to analyze the three-dimensional fluorescence data and export the results.

8. The method according to claim 4, wherein The steps of S2-Fourier transform infrared spectroscopy combined with two-dimensional correlation spectroscopy analysis are as follows: S21, collecting infrared spectrum data of the sample by Fourier infrared spectroscopy technology, and arranging the data into a three-dimensional data matrix; S22, performing a two-dimensional Fourier transform on the matrix data in step S21 to generate a two-dimensional related synchronous spectrum and asynchronous spectrum.

9. The method according to claim 4, wherein S3-Gel Permeation Chromatography, Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and Machine Learning The specific steps are as follows: S31, by passing the sample solution through a chromatographic column filled with porous gel, the molecules of different molecular sizes are separated according to their penetration degree in the pores, and the relative molecular weight of the substance is calculated by detecting the time it takes for different molecules to flow out of the column; S32. After testing the samples obtained during the far-UV / peracetic acid disinfection process, the known hydrocarbon compounds in the dissolved organic matter were used for internal standard calibration. After calibration, the mass spectrometry data was matched with molecular formulas according to the standard of S / N>4. The screening conditions included retaining the hydrogen-carbon ratio and oxygen-carbon ratio within a specific range, and screening the qualified molecular formulas according to the deoxy double bond equivalent value; S33, analyzing the detected mass spectrum peaks, the results including molecular formulas and corresponding molecular compositions; S34. Divide the data of Fourier transform ion cyclotron resonance mass spectrometry analysis into a training set and a test set, use grid search to optimize the hyperparameters of the XGBoost model, train the final model and make predictions, use Shapley additive explanation values for feature importance analysis, and visualize the results through a Sankey diagram, so as to evaluate the influence of the molecular characteristics of substances on the molecular reaction characteristics during the far ultraviolet / peracetic acid disinfection process.

10. The method according to claim 4, wherein S4 - The specific steps of electron paramagnetic resonance analysis are as follows: S41. Select a suitable electron spin trap and add it to the water sample + far ultraviolet / peracetic acid system and the deionized water + far ultraviolet / peracetic acid system; S42. Use electron paramagnetic resonance technology to detect the spectral signals of the capturer adducts of the samples collected from the water sample + far ultraviolet / peracetic acid system and the deionized water + far ultraviolet / peracetic acid system respectively, and analyze their characteristic heterodyne signals, so as to determine the types and relative concentrations of oxidizing active species; The electron spin trap is selected from one of 5-(diisopropoxyphosphoryl)-5-methyl-1-pyrroline N-oxide, 5,5-dimethyl-1-pyrroline-N-oxide, and 2,2,6,6-tetramethylpiperidine.

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