Evaluation method of sewage treatment process

Abstract

The invention relates to the technical field of water quality detection and evaluation, and provides an evaluation method of a sewage treatment process, which can trace the degradation conditions of different sewage treatment processes on different molecular weight components of organic pollutants by combining an ultrafiltration technology and a three-dimensional fluorescence spectrometry, and can quickly evaluate refractory soluble organic matters in sewage at the same time. In the evaluation process, the separation operation of organic matters is simplified through ultrafiltration, and the cost is reduced; the degradation conditions of different molecular weight components of organic pollutants by different sewage treatment processes can be traced by combining specific ultrafiltration conditions with three-dimensional fluorescence spectrum analysis and a specific calculation formula for the content of the refractory soluble organic matters specified by the invention, and the refractory soluble organic matters in the sewage can be rapidly evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of water quality detection and evaluation, and in particular to an evaluation method for a sewage treatment process. Background Art

[0002] Sewage contains dissolved organic matter (DOM), which is a class of organic mixtures with complex composition, structure and environmental behavior. In a broad sense, it includes all organic compounds dissolved in water, usually referring to heterogeneous hydrocarbon mixtures dissolved in water, acid or alkaline solutions that can pass through a 0.45μm filter membrane, and are composed of functional groups such as amino acids, aromatics, and aliphatics containing oxygen, nitrogen and sulfur. This type of substance is difficult to degrade, has a complex structure, a large molecular weight and is soluble in water. Therefore, in the sewage treatment process of existing technologies, the removal of dissolved organic matter must be achieved through a variety of technologies, including physical adsorption, advanced oxidation and biological treatment. Different sewage treatment processes must have different degradation conditions for DOM in sewage. How to choose a suitable treatment process according to the sewage conditions is crucial for the proper harmless treatment of sewage.

[0003] CN111707652A discloses a method for evaluating the biodegradation potential of estrogens in water bodies based on three-dimensional fluorescence spectroscopy. Specifically, surface water samples S1, S2…S7 from different rivers, lakes, etc. are collected, filtered with a 0.45μm glass fiber filter membrane, and the total organic carbon TOC concentration is determined; the excitation-emission three-dimensional fluorescence spectrum of the water sample after scanning is processed, and Raman scattering correction and Rayleigh scattering influence are deducted; finally, the percentage content of biodegradable fluorescent organic matter in the sample is calculated. Although tyrosine-like, tryptophan-like, fulvic acid-like, and humic acid-like are used as detection targets in this technical solution, due to the differences in the degradation difficulty of these substances at different molecular weight levels, this difference may cause deviations in the results. Similarly, CN115165825A discloses a method for evaluating the biodegradability of wastewater from the printing and dyeing industry based on three-dimensional fluorescence spectroscopy. It only uses a simple 0.45μm filter membrane for filtration, and also measures the biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) in the water according to national standards. However, the BOD5 measurement cycle is as long as 5 days, which means that although the technical solution has complete data, the test results can only be obtained within half an hour after at least five days, but it is impossible to conduct more refined and rapid analysis and evaluation of the water quality obtained after the sewage treatment process.

[0004] CN111003874B discloses a method for graded treatment of sewage tail water polluted by dissolved organic matter, which method includes: filtering and pre-treating the sewage tail water polluted by dissolved organic matter to obtain intermediate sewage I; passing the intermediate sewage I through a first ultrafiltration membrane with a membrane pore size of 10kDa and a second ultrafiltration membrane with a membrane pore size of 5kDa in turn, and performing secondary ultrafiltration treatment to obtain primary sewage, secondary sewage and tertiary sewage respectively; and then adding magnetic powder, flocculant and coagulant aid to the sewage at each level respectively, and mixing the effluents at each level to obtain the total effluent after graded treatment. However, this technical solution is to apply ultrafiltration to the process of sewage treatment, and it is not to apply ultrafiltration technology to the analysis and evaluation of organic pollutants and their contents after sewage treatment.

[0005] CN113484294A discloses a diagnostic method for the binding ability of dissolved organic carbon with metals of different valence electron configurations, which belongs to the field of water body ecological technology. First, through ultrafiltration classification technology, dissolved organic carbon (DOC) components of different molecular weights are obtained, including 0.1-1kDa, 1-5 kDa, 5-10 kDa, and 10-100 kDa DOC; then, different molecular weight DOCs are subjected to fluorescence quenching titration experiments with metal ions of different valence electron configurations (p, d, s regions) on the periodic table; after the experiment, the three-dimensional fluorescence spectra of different molecular weight DOCs before and after the titration experiment are measured, and the fluorescent components involved in the binding and the fluorescence quenching curves of each component are obtained through parallel factor analysis (PARAFAC); finally, the modified Stren-Volmer model is used to calculate the binding parameters of different fluorescent components with metals of different valence electron configurations, and the affinity differences between different components and metals are obtained. This technical solution performs ultrafiltration classification before conducting detailed spectral analysis of the substance. However, the above technical solution can only effectively analyze DOC (referring to the mass of carbon element therein), and based on the characteristics of DOC, a fluorescence quenching titration experiment with metal ions is specifically adopted. However, for complex organic pollutants such as DOM, which includes the mass of other elements present in organic matter (such as nitrogen, oxygen, hydrogen, etc.), dissolved organic matter, and the main components are polysaccharides, amino acids, etc., it is not known whether the above method is feasible.

[0006] Based on the above situation, the existing technology still has evaluation deviations for the water quality obtained by different sewage treatment processes, and is unable to make timely and effective adjustments to the treatment plans for different types of sewage based on the evaluation results, ultimately leading to technical problems that need to be solved urgently, such as unqualified sewage treatment and substandard emissions. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a method for evaluating a sewage treatment process, comprising the following steps: Step 1: Take the water quality before and after the sewage treatment process and perform preliminary filtration on the water quality; Step 2, performing graded ultrafiltration on the filtrate after preliminary filtration; Step 3, performing three-dimensional fluorescence scanning on the filtrate after the preliminary filtration in step 1 and the filtrate of each level after the graded filtration in step 2; Step 4, performing parallel factor analysis on the data of the three-dimensional fluorescence spectrum in step 3, obtaining the fluorescence intensity corresponding to each substance in DOM, and obtaining the degradation of DOM by the sewage treatment process; The various substances in the DOM include tryptophan-like substances, tyrosine-like substances, and humus-like substances; Step 5: The fluorescence intensities of tryptophan-like, tyrosine-like, and humus-like substances after primary filtration are recorded as F A1 、F A2 、F A3 The fluorescence intensity of tryptophan-like and tyrosine-like after any stage of filtration in the graded filtration is recorded as F B1 、F B2 , the content of difficult-to-degrade dissolved organic matter in the sewage treatment process is calculated according to the following formula: .

[0008] Furthermore, the tryptophan-like substances are substances that are similar to tryptophan in terms of properties, structure or spectral characteristics; similarly, the tyrosine-like substances are substances that are similar to tyrosine in terms of properties, structure or spectral characteristics; the humus-like substances are substances that are similar to humus in terms of chemical structure, physicochemical properties and spectral characteristics.

[0009] Furthermore, the difficultly degradable soluble organic matter is defined as soluble organic matter that is difficult to be utilized by organisms in biological treatment.

[0010] Furthermore, the sewage treatment process includes one or a combination of physical, chemical and biological methods.

[0011] Furthermore, the physical method includes but is not limited to activated carbon adsorption and resin adsorption.

[0012] Furthermore, the chemical method includes but is not limited to Fenton oxidation method.

[0013] Furthermore, the biological method includes but is not limited to aerated biological filter (Biological Aerated Filter, BAF).

[0014] Furthermore, the preliminary filtration in step 1 uses a 0.45 μm filter membrane.

[0015] Furthermore, in step 2, the order of graded filtration is 10 kDa, 3 kDa, and 1 kDa ultrafiltration membranes.

[0016] Furthermore, nitrogen pressure filtration is used in the graded filtration in step 2.

[0017] Furthermore, the pressure of the pressure filtration is 0.1-0.22 MPa.

[0018] Furthermore, in step 3, before performing the three-dimensional fluorescence scanning, the absorbance of the filtrate is measured.

[0019] Furthermore, the absorbance was measured using a UV-visible spectrophotometer with a wavelength set at 254 nm; When the absorbance is less than or equal to 0.1, a three-dimensional fluorescence scan is performed directly; when the absorbance is greater than 0.1, the filtrate is diluted and the dilution multiple is recorded until the absorbance is less than or equal to 0.1, and then a three-dimensional fluorescence scan is performed to reduce the influence of the inner filter effect on the three-dimensional fluorescence data.

[0020] Furthermore, the scanning parameters of the three-dimensional fluorescence scanning in step 3 are: excitation wavelength 200-500 nm, emission wavelength 220-550 nm, step length 2 nm, scanning speed 12000 nm / min, and slit width 5 nm.

[0021] Furthermore, in addition to performing a three-dimensional fluorescence scan on the filtrate, it is also necessary to perform a three-dimensional fluorescence scan on the pure water to obtain three-dimensional fluorescence spectrum data of the pure water.

[0022] Furthermore, the main feature of the three-dimensional fluorescence spectrum (3DEEM, Three-Dimension Excitation Emission Matrix Fluorescence Spectrum) that distinguishes it from ordinary fluorescence analysis is that it can obtain fluorescence intensity information when the excitation wavelength and the emission wavelength change simultaneously. In a three-dimensional fluorescence spectrum of a multi-component system, each component has a specific spectral region of independent excitation and emission.

[0023] Furthermore, before performing the parallel factor analysis in step 3, the three-dimensional fluorescence data is pre-processed, including background subtraction, removal of Rayleigh scattering and Raman scattering, to prevent the influence on the result of the parallel factor analysis.

[0024] Furthermore, the Rayleigh scattering is a kind of elastic scattering, and the photons from the excitation source bounce off in all directions after encountering the molecules in the solution, wherein the emission wavelength of the Rayleigh scattering is completely equal to the excitation wavelength.

[0025] Furthermore, the Raman scattering is an inelastic scattering, and compared with Rayleigh scattering, a much smaller proportion of photons from the excitation source impact the molecules and cause inelastic scattering.

[0026] Furthermore, the background subtraction is to subtract the three-dimensional fluorescence data of pure water from the three-dimensional fluorescence data of the filtrate.

[0027] Furthermore, the Delaunay triangulation method was used to interpolate the three-dimensional fluorescence data after background subtraction to remove Rayleigh scattering and Raman scattering.

[0028] Furthermore, the Delaunay triangulation method is an interpolation method, which first triangulates all data points, that is, constructs a network composed of triangles, and the value in each triangle is calculated by polynomial interpolation. The result of using Delaunay triangulation is smoother and more continuous than that of simple interpolation methods.

[0029] Furthermore, the descattered three-dimensional fluorescence data were subjected to parallel factor analysis using trilinear theory.

[0030] Furthermore, the parallel factor analysis is based on the trilinear decomposition theory and adopts a three-dimensional matrix decomposition algorithm based on the alternating least squares principle to reduce the dimension of the excitation-emission three-dimensional matrix into three loading matrices, thereby analyzing the three-dimensional fluorescence spectrum.

[0031] Furthermore, if the filtrate is diluted before the three-dimensional fluorescence scanning, the fluorescence intensity should be amplified by a corresponding multiple according to the dilution multiple to obtain an accurate fluorescence intensity.

[0032] Furthermore, the excitation wavelength of the tryptophan-like fluorescence peak center is 220-280nm, and the emission wavelength is 330-380nm; The excitation wavelength of the tyrosine-like fluorescence peak center is 250-300 nm, and the emission wavelength is 300-350 nm; The excitation wavelengths of the humic acid-like fluorescence peak centers are respectively 228-250 nm and 310-326 nm, and the emission wavelength is 410-436 nm.

[0033] Furthermore, in step 5, the fluorescence intensities of tryptophan-like and tyrosine-like in the graded filtration after the 3 kDa primary filtration are recorded as F B1 、F B2 .

[0034] Furthermore, the results of DOM degradation by different sewage treatment processes are evaluated according to the degradation conditions in step 4 and the content of refractory soluble organic matter in step 5, and a suitable sewage treatment process is selected based on the results to quickly and effectively degrade DOM in various types of sewage.

[0035] The present invention also provides a sewage treatment process evaluation database established using the above-mentioned sewage treatment process evaluation method. The database is used to provide fast, reliable and clear guidance on which sewage treatment process to select, or how to combine different sewage treatment processes to achieve better treatment effects, provide data experience and theoretical analysis for related engineering construction, and reduce the trial and error costs in the sewage treatment process.

[0036] Furthermore, the data collected by the database include but are not limited to DOM data before and after sewage treatment by different sewage treatment processes in different regions or parks, or DOM data before and after sewage treatment by different sewage treatment processes in different time periods in the same region or park, or DOM data before and after sewage treatment by any combination of different sewage treatment processes.

[0037] The beneficial effects of the present invention are: 1. The present invention provides a method for evaluating a sewage treatment process. By combining ultrafiltration technology and three-dimensional fluorescence spectroscopy, the degradation of different molecular weight components of organic pollutants by different sewage treatment processes can be traced, and the difficult-to-degrade soluble organic matter in sewage can be quickly evaluated. In the evaluation process of the present invention, ultrafiltration simplifies the separation operation of organic matter and reduces the cost. The specific ultrafiltration conditions combined with three-dimensional fluorescence spectroscopy and the specific difficult-to-degrade soluble organic matter content calculation formula specified in the present invention can trace different sewage treatment processes, that is, the order of graded filtration uses 10kDa, 3kDa, and 1kDa ultrafiltration membranes in turn, and the fluorescence intensities of tryptophan-like, tyrosine-like, and humus-like after primary filtration are respectively recorded as F A1 、F A2 、F A3 The fluorescence intensity of tryptophan and tyrosine-like samples after filtration through a 3kDa ultrafiltration membrane is recorded as F B1 、F B2 , the content of difficult-to-degrade dissolved organic matter in the sewage treatment process is calculated according to the following formula: , It can realize the degradation of different molecular weight components of organic pollutants and quickly and accurately evaluate the difficult-to-degrade soluble organic matter in sewage; 2. The soluble COD of sewage was detected by the detection method of COD value in the national standard GB11914-1989. The test results show that the content of difficult-to-degrade soluble organic matter obtained by the evaluation method adopted in the present invention is closer to the test result of the national standard, has high reliability, and avoids the defects of the traditional national standard detection method, such as being easily interfered by chloride ions, having a delicate and complicated operation process, being time-consuming, and using a reagent, mercuric sulfate, which is a highly toxic substance and causes certain harm to the human body and the environment; 3. The three-dimensional fluorescence spectroscopy method used in the present invention provides a simpler operation process and more intuitive data interpretation than mass spectrometry or LC-OCD when analyzing the types of organic matter in sewage, which is convenient for rapid and accurate analysis without relying on expensive precision instruments; the combination of ultrafiltration and three-dimensional fluorescence method reduces the test cost and saves test time; that is, the evaluation method of the present invention has simple steps, low cost, low operation time, and accurate, reliable and stable test results; compared with the prior art such as chromatography-mass spectrometry, which requires the use of relevant precision equipment, is limited by standard samples during testing, and is expressed by functional groups as the standard, there are inaccuracies , and may not fully reflect the types of pollutants in the wastewater; or liquid chromatography-organic carbon detection (LC-OCD) also requires precision equipment, the test is complex and time-consuming, and has high requirements for the clarity of the sample. It is not applicable to industrial wastewater, and a single sample takes about 2 hours. If it is unknown wastewater, the chromatographic conditions need to be debugged, and the time cannot be estimated, and the subsequent spectrum interpretation is not as mature as three-dimensional fluorescence spectroscopy; or in mass spectrometry, a single sample is tested for about 30-60 minutes, and qualitative results can be obtained. If you want to obtain quantitative results, you need to purchase standard samples, but the types of substances in actual wastewater are many and complex, making it difficult to evaluate; 4. According to the evaluation method of the specific sewage treatment process of the present invention, a database of sewage treatment results of different treatment processes or different regions can be established. In the process of establishment and improvement, the database can provide fast, reliable and clear guidance for selecting which sewage treatment process to use or how to match and combine the sewage treatment processes to achieve better treatment effects, provide data experience and theoretical analysis for subsequent engineering construction, and reduce the trial and error costs in the sewage treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The three-dimensional fluorescence data after pre-processing in Example 1 of the present invention; Figure 2 It is a spectrum of each component in DOM in Example 1 of the present invention; Figure 3 The three-dimensional fluorescence data after pre-processing in Example 2 of the present invention; Figure 4 is a spectrum of each component in DOM in Example 2 of the present invention; Figure 5 The three-dimensional fluorescence data after pre-processing in Example 3 of the present invention; Figure 6 This is a graph of the components in DOM in Example 3 of the present invention. DETAILED DESCRIPTION

[0039] To ensure the comparability of the experimental results, the sewage used in the following examples was sampled at the same time and location from a certain industrial park in Jiangsu Province. However, the evaluation method of the present invention is not limited to the sampling location of the above sewage, and sewage from any location can be evaluated using the evaluation method of the present invention.

[0040] Example 1 This embodiment provides a method for evaluating a sewage treatment process (in this embodiment, a biological aerated filter, BAF), specifically a method for evaluating DOM degradation, including the following steps: Step 1, take 150mL of water before and after the sewage treatment process, record them as influent and produced water, respectively, use 0.45μm filter membrane to filter the water, and the filtrates obtained are recorded as influent 1 and produced water 1 respectively; Step 2, taking the influent 1 and the produced water 1 after preliminary filtration and performing graded nitrogen pressure filtration ultrafiltration respectively; in this embodiment, 10kDa, 3kDa, and 1kDa ultrafiltration membranes are used in sequence, and the pressure range of the pressure filtration is controlled within 0.1-0.22MPa; Specifically, 100 ml of influent 1 is filtered using a 10 kDa ultrafiltration membrane to obtain influent 2, at which the molecular weight of DOM in influent 2 is less than 10 kDa; 70 ml of influent 2 was taken and filtered using a 3 kDa ultrafiltration membrane to obtain influent 3. At this time, the molecular weight of DOM in influent 3 was less than 3 kDa; 50 ml of influent 3 was taken and filtered using a 1 kDa ultrafiltration membrane to obtain influent 4. At this time, the molecular weight of DOM in influent 4 was less than 1 kDa; Similarly, water production 2, water production 3, and water production 4 are obtained in sequence; Among them, the amount of water taken in step 1 is only 150 ml, so the filtration time is reduced, and the time taken in step 1 and step 2 is 2 hours; Step 3, performing three-dimensional fluorescence scanning on the filtrate after the preliminary filtration in step 1 and the filtrate of each level after the graded filtration in step 2; Taking influent 1 as an example, the specific steps of three-dimensional fluorescence scanning are described as follows: 3 mL of influent 1 is taken, and the absorbance of the filtrate at 254 nm is measured using an ultraviolet-visible spectrophotometer. In this embodiment, the absorbance of the influent 1 is greater than 0.1, so the influent 1 is diluted 6 times, and the absorbance of the influent 1 is less than 0.1. Then 1 mL of the sample is taken for three-dimensional fluorescence scanning, and the scanning parameters are: excitation wavelength 200-500 nm, emission wavelength 220-550 nm, step length 2 nm, scanning speed 12000 nm / min, slit width 5 nm, and three-dimensional fluorescence data of the first filtrate of the influent is obtained; The three-dimensional fluorescence data of influent 2 (dilution factor of 6), influent 3 (dilution factor of 4), influent 4 (dilution factor of 4), and produced water 1 (dilution factor of 5), produced water 2 (dilution factor of 5), produced water 3 (dilution factor of 4), and produced water 4 (dilution factor of 4) were obtained in sequence; At the same time, in addition to performing a three-dimensional fluorescence scan on the filtrate, this embodiment also requires performing a three-dimensional fluorescence scan on the pure water to obtain three-dimensional fluorescence data of the pure water; Among them, since the volume of each sample during testing is less than 10mL, the processing time of each sample is less than 30min, and the subsequent data analysis can produce results within 1h, the total time of this step is 4-5h; Step 4: Before performing parallel factor analysis, the three-dimensional fluorescence data is pre-processed, including background subtraction, Rayleigh scattering and Raman scattering removal; The background subtraction is to subtract the fluorescence data of pure water from each three-dimensional fluorescence data obtained in step 3; then the Delaunay triangulation method in the prior art is used to interpolate the three-dimensional fluorescence data after background subtraction to remove Rayleigh scattering and Raman scattering, so as to avoid the influence of the two scattering on subsequent data, such as Figure 1 As shown, the three-dimensional fluorescence data after pre-processing is obtained; Then, based on the trilinear theory in the prior art, parallel factor analysis was performed on the pre-processed three-dimensional fluorescence data, such as Figure 2 As shown, the spectra of the tryptophan-like, tyrosine-like, and humus-like components in this embodiment are obtained (if the sample is diluted, the fluorescence intensity should be amplified according to the dilution multiple); The excitation wavelength of the tryptophan-like fluorescence peak center is 220-280nm, and the emission wavelength is 330-380nm; the excitation wavelength of the tyrosine-like fluorescence peak center is 250-300nm, and the emission wavelength is 300-350nm; the excitation wavelength of the humic acid-like fluorescence peak center is 228-250nm and 310-326nm, and the emission wavelength is 410-436nm; Combination Figure 1 and Figure 2 The results show that the fluorescence intensity corresponding to different substances in each sample in this embodiment is shown in Table 1: Table 1 Fluorescence intensity of different substances in each sample in Example 1

[0041] From Table 1, the corresponding fluorescence intensity of each sample in different molecular diameter or molecular weight range can be calculated. The specific calculation method is to subtract the fluorescence intensity of tryptophan-like in influent 1 (passed through 0.45μm filter membrane) from the fluorescence intensity of tryptophan-like in influent 2 (passed through 10kDa ultrafiltration membrane), the fluorescence intensity of tryptophan-like in influent 2 (passed through 10kDa ultrafiltration membrane) from the fluorescence intensity of tryptophan-like in influent 3 (passed through 3kDa ultrafiltration membrane), the fluorescence intensity of tryptophan-like in influent 3 (passed through 3kDa ultrafiltration membrane) from the fluorescence intensity of tryptophan-like in influent 4 (passed through 1kDa ultrafiltration membrane). The intensity can be used to obtain the fluorescence intensity of tryptophan-like molecules with molecular weight or molecular diameter of 10kDa-0.45μm, 3kDa-10kDa, 1kDa-3kDa in the influent water; similarly, the fluorescence intensity of tyrosine-like and humic acid-like molecules with molecular weight or molecular diameter of 10kDa-0.45μm, 3kDa-10kDa, 1kDa-3kDa in the influent water can be obtained; similarly, the fluorescence intensity of tryptophan-like, tyrosine-like and humic acid-like molecules with molecular weight or molecular diameter of 10kDa-0.45μm, 3kDa-10kDa, 1kDa-3kDa in the produced water can be obtained.

[0042] The calculation results are shown in Table 2: Table 2 Fluorescence intensity of samples in different molecular diameter or molecular weight ranges

[0043] Step 5: The fluorescence intensities of tryptophan-like, tyrosine-like, and humus-like substances after primary filtration are recorded as F A1 、F A2 、F A3 The fluorescence intensity of tryptophan-like and tyrosine-like after passing through the 3kDa ultrafiltration membrane in the graded filtration was recorded as F B1 、F B2 , according to the following formula: , Calculate the content of refractory dissolved organic matter in the influent of sewage treatment process: The content of difficult-to-degrade organic matter in the influent water = 1-(26.8+19.2) / (46.6+27.2+50.7)=63%.

[0044] The results of evaluating the DOM degradation of the BAF wastewater treatment process based on the degradation in step 4 and the content of difficult-to-degrade soluble organic matter in step 5 show that in the BAF wastewater treatment process, the 1-3 kDa tryptophan-like substances are mainly removed.

[0045] Based on the above results, when the sewage contains a large amount of 1-3kDa tryptophan-like substances, the BAF sewage treatment process is directly used for rapid sewage treatment.

[0046] Example 2 This embodiment provides a method for evaluating a sewage treatment process (in this embodiment, a Fenton oxidation method is used), specifically a method for evaluating DOM degradation, comprising the following steps: Step 1, take 150mL of water before and after the sewage treatment process, record them as influent and produced water, respectively, use 0.45μm filter membrane to filter the water, and the filtrates obtained are recorded as influent 1 and produced water 1 respectively; Step 2, taking the influent 1 and the produced water 1 after preliminary filtration and performing graded nitrogen pressure filtration ultrafiltration respectively; in this embodiment, 10kDa, 3kDa, and 1kDa ultrafiltration membranes are used in sequence, and the pressure range of the pressure filtration is controlled within 0.1-0.22MPa; Specifically, 100 ml of influent 1 is filtered using a 10 kDa ultrafiltration membrane to obtain influent 2, at which the molecular weight of DOM in influent 2 is less than 10 kDa; 70 ml of influent 2 was taken and filtered using a 3 kDa ultrafiltration membrane to obtain influent 3. At this time, the molecular weight of DOM in influent 3 was less than 3 kDa; 50 ml of influent 3 was taken and filtered using a 1 kDa ultrafiltration membrane to obtain influent 4. At this time, the molecular weight of DOM in influent 4 was less than 1 kDa; Similarly, produced water 2, produced water 3, and produced water 4 are obtained in sequence.

[0047] Step 3, performing three-dimensional fluorescence scanning on the filtrate after the preliminary filtration in step 1 and the filtrate of each level after the graded filtration in step 2; Taking influent 1 as an example, the specific steps of three-dimensional fluorescence scanning are described as follows: 3 mL of influent 1 is taken, and the absorbance of the filtrate at 254 nm is measured using an ultraviolet-visible spectrophotometer. In this embodiment, the absorbance of the influent 1 is greater than 0.1, so the influent 1 is diluted 6 times, and the absorbance of the influent 1 is less than 0.1. Then 1 mL of the sample is taken for three-dimensional fluorescence scanning, and the scanning parameters are: excitation wavelength 200-500 nm, emission wavelength 220-550 nm, step length 2 nm, scanning speed 12000 nm / min, slit width 5 nm, and three-dimensional fluorescence data of the first filtrate of the influent is obtained; The three-dimensional fluorescence data of influent 2 (dilution factor of 6), influent 3 (dilution factor of 4), influent 4 (dilution factor of 4), and produced water 1 (undiluted), produced water 2 (undiluted), produced water 3 (undiluted), and produced water 4 (undiluted) were obtained in turn; At the same time, in addition to performing a three-dimensional fluorescence scan on the filtrate, this embodiment also requires performing a three-dimensional fluorescence scan on the pure water to obtain three-dimensional fluorescence data of the pure water.

[0048] Step 4: Before performing parallel factor analysis, the three-dimensional fluorescence data is pre-processed, including background subtraction, Rayleigh scattering and Raman scattering removal; The background subtraction is to subtract the fluorescence data of pure water from each three-dimensional fluorescence data obtained in step 3; then the Delaunay triangulation method in the prior art is used to interpolate the three-dimensional fluorescence data after background subtraction to remove Rayleigh scattering and Raman scattering, so as to avoid the influence of the two scattering on subsequent data, such as Figure 3 As shown, the three-dimensional fluorescence data after pre-processing is obtained; Then, based on the trilinear theory in the prior art, parallel factor analysis was performed on the pre-processed three-dimensional fluorescence data, such as Figure 4 As shown, the spectra of the tryptophan-like, tyrosine-like, and humus-like components in this embodiment are obtained (if the sample is diluted, the fluorescence intensity should be amplified according to the dilution multiple); The excitation wavelength of the tryptophan-like fluorescence peak center is 220-280nm, and the emission wavelength is 330-380nm; the excitation wavelength of the tyrosine-like fluorescence peak center is 250-300nm, and the emission wavelength is 300-350nm; the excitation wavelength of the humic acid-like fluorescence peak center is 228-250nm and 310-326nm, and the emission wavelength is 410-436nm; Combination Figure 3 and Figure 4 The results show that the fluorescence intensity corresponding to different substances in each sample in this embodiment is shown in Table 3: Table 3 Fluorescence intensity of different substances in each sample in Example 2

[0049] From Table 1, the corresponding fluorescence intensity of each sample in different molecular diameter or molecular weight range can be calculated. The specific calculation method is to subtract the fluorescence intensity of tryptophan-like in influent 1 (passed through 0.45μm filter membrane) from the fluorescence intensity of tryptophan-like in influent 2 (passed through 10kDa ultrafiltration membrane), the fluorescence intensity of tryptophan-like in influent 2 (passed through 10kDa ultrafiltration membrane) from the fluorescence intensity of tryptophan-like in influent 3 (passed through 3kDa ultrafiltration membrane), the fluorescence intensity of tryptophan-like in influent 3 (passed through 3kDa ultrafiltration membrane) from the fluorescence intensity of tryptophan-like in influent 4 (passed through 1kDa ultrafiltration membrane). The intensity can be used to obtain the fluorescence intensity of tryptophan-like molecules with molecular weight or molecular diameter of 10kDa-0.45μm, 3kDa-10kDa, 1kDa-3kDa in the influent water; similarly, the fluorescence intensity of tyrosine-like and humic acid-like molecules with molecular weight or molecular diameter of 10kDa-0.45μm, 3kDa-10kDa, 1kDa-3kDa in the influent water can be obtained; similarly, the fluorescence intensity of tryptophan-like, tyrosine-like and humic acid-like molecules with molecular weight or molecular diameter of 10kDa-0.45μm, 3kDa-10kDa, 1kDa-3kDa in the produced water can be obtained.

[0050] The calculation results are shown in Table 4: Table 4 Fluorescence intensity of samples in different molecular diameter or molecular weight ranges

[0051] Step 5: The fluorescence intensities of tryptophan-like, tyrosine-like, and humus-like substances after primary filtration are recorded as F A1 、F A2 、F A3 The fluorescence intensity of tryptophan-like and tyrosine-like after passing through the 3kDa ultrafiltration membrane in the graded filtration was recorded as F B1 、F B2 , according to the following formula: , Calculate the content of refractory dissolved organic matter in the produced water during the sewage treatment process: The content of difficult-to-degrade organic matter in the produced water = 1-(0.3+0.3) / (1.1+0.3+0.4) = 67%.

[0052] The results of evaluating the degradation of DOM by the Fenton oxidation wastewater treatment process are based on the degradation conditions in step 4 and the content of difficult-to-degrade soluble organic matter in step 5. It can be seen that in the Fenton oxidation wastewater treatment process, soluble organic matter is gradually decomposed from large molecules to small molecules, which is beneficial to reducing molecular diameter and molecular weight.

[0053] Based on the above results, when the sewage contains a large amount of macromolecular dissolved organic matter, the Fenton oxidation method is directly used for rapid sewage treatment.

[0054] Example 3 This embodiment provides a method for evaluating a sewage treatment process (using activated carbon adsorption in this embodiment), specifically, a method for evaluating DOM degradation, comprising the following steps: Step 1, take 150mL of water before and after the sewage treatment process, record them as influent and produced water, respectively, use 0.45μm filter membrane to filter the water, and the filtrates obtained are recorded as influent 1 and produced water 1 respectively; Step 2, taking the influent 1 and the produced water 1 after preliminary filtration and performing graded nitrogen pressure filtration ultrafiltration respectively; in this embodiment, 10kDa, 3kDa, and 1kDa ultrafiltration membranes are used in sequence, and the pressure range of the pressure filtration is controlled within 0.1-0.22MPa; Specifically, 100 ml of influent 1 is filtered using a 10 kDa ultrafiltration membrane to obtain influent 2, at which the molecular weight of DOM in influent 2 is less than 10 kDa; 70 ml of influent 2 was taken and filtered using a 3 kDa ultrafiltration membrane to obtain influent 3. At this time, the molecular weight of DOM in influent 3 was less than 3 kDa; 50 ml of influent 3 was taken and filtered using a 1 kDa ultrafiltration membrane to obtain influent 4. At this time, the molecular weight of DOM in influent 4 was less than 1 kDa; Similarly, produced water 2, produced water 3, and produced water 4 are obtained in sequence.

[0055] Step 3, performing three-dimensional fluorescence scanning on the filtrate after the preliminary filtration in step 1 and the filtrate of each level after the graded filtration in step 2; Taking influent 1 as an example, the specific steps of three-dimensional fluorescence scanning are described as follows: 3 mL of influent 1 is taken, and the absorbance of the filtrate at 254 nm is measured using a UV-visible spectrophotometer. In this embodiment, the absorbance of the influent 1 is less than 0.1, and three-dimensional fluorescence scanning can be performed directly. The scanning parameters are: excitation wavelength 200-500 nm, emission wavelength 220-550 nm, step length 2 nm, scanning speed 12000 nm / min, slit width 5 nm, and three-dimensional fluorescence data of the first filtrate of the influent is obtained; The three-dimensional fluorescence data of influent 2 (undiluted), influent 3 (undiluted), influent 4 (undiluted), and produced water 1 (undiluted), produced water 2 (undiluted), produced water 3 (undiluted), and produced water 4 (undiluted) are obtained in sequence; At the same time, in addition to performing a three-dimensional fluorescence scan on the filtrate, this embodiment also requires performing a three-dimensional fluorescence scan on the pure water to obtain three-dimensional fluorescence data of the pure water.

[0056] Step 4: Before performing parallel factor analysis, the three-dimensional fluorescence data is pre-processed, including background subtraction, Rayleigh scattering and Raman scattering removal; The background subtraction is to subtract the fluorescence data of pure water from each three-dimensional fluorescence data obtained in step 3; then the Delaunay triangulation method in the prior art is used to interpolate the three-dimensional fluorescence data after background subtraction to remove Rayleigh scattering and Raman scattering, so as to avoid the influence of the two scattering on subsequent data, such as Figure 5 As shown, the three-dimensional fluorescence data after pre-processing is obtained; Then, based on the trilinear theory in the prior art, parallel factor analysis was performed on the pre-processed three-dimensional fluorescence data, such as Figure 6 As shown, the spectra of the tryptophan-like, tyrosine-like, and humus-like components in this embodiment are obtained; The excitation wavelength of the tryptophan-like fluorescence peak center is 220-280nm, and the emission wavelength is 330-380nm; the excitation wavelength of the tyrosine-like fluorescence peak center is 250-300nm, and the emission wavelength is 300-350nm; the excitation wavelength of the humic acid-like fluorescence peak center is 228-250nm and 310-326nm, and the emission wavelength is 410-436nm; Combination Figure 5 and Figure 6 The results show that the fluorescence intensity corresponding to different substances in each sample in this embodiment is shown in Table 5: Table 5 Fluorescence intensity of different substances in each sample in Example 3

[0057] From Table 1, the corresponding fluorescence intensity of each sample in different molecular diameter or molecular weight range can be calculated. The specific calculation method is to subtract the fluorescence intensity of tryptophan-like in influent 1 (passed through 0.45μm filter membrane) from the fluorescence intensity of tryptophan-like in influent 2 (passed through 10kDa ultrafiltration membrane), the fluorescence intensity of tryptophan-like in influent 2 (passed through 10kDa ultrafiltration membrane) from the fluorescence intensity of tryptophan-like in influent 3 (passed through 3kDa ultrafiltration membrane), the fluorescence intensity of tryptophan-like in influent 3 (passed through 3kDa ultrafiltration membrane) from the fluorescence intensity of tryptophan-like in influent 4 (passed through 1kDa ultrafiltration membrane). The light intensity can be used to obtain the fluorescence intensity of tryptophan-like molecules with molecular weight or molecular diameter of 10kDa-0.45μm, 3kDa-10kDa, 1kDa-3kDa in the influent water; similarly, the fluorescence intensity of tyrosine-like and humic acid-like molecules with molecular weight or molecular diameter of 10kDa-0.45μm, 3kDa-10kDa, 1kDa-3kDa in the influent water can be obtained; similarly, the fluorescence intensity of tryptophan-like, tyrosine-like and humic acid-like molecules with molecular weight or molecular diameter of 10kDa-0.45μm, 3kDa-10kDa, 1kDa-3kDa in the produced water can be obtained. The calculation results are shown in Table 6: Table 6 Fluorescence intensity of samples in different molecular diameters or molecular weight ranges

[0058] Step 5: The fluorescence intensities of tryptophan-like, tyrosine-like, and humus-like substances after primary filtration are recorded as F A1 、F A2 、F A3 The fluorescence intensity of tryptophan-like and tyrosine-like after passing through the 3kDa ultrafiltration membrane in the graded filtration was recorded as F B1 、F B2 , according to the following formula: , Calculate the content of refractory dissolved organic matter in the produced water during the sewage treatment process: The content of difficult-to-degrade organic matter in the produced water = 1-(0.13+0.05) / (0.86+0.34+0.16) = 87%.

[0059] The results of evaluating the degradation of DOM by the activated carbon adsorption wastewater treatment process are based on the degradation conditions in step 4 and the content of difficult-to-degrade soluble organic matter in step 5. It can be seen that in the activated carbon adsorption wastewater treatment process, the adsorption method has a good removal effect on various organic matter in DOM, especially for organic matter with a molecular weight <1kDa.

[0060] Through the above results, the adsorption method can be applied to the removal of various types of organic matter, especially when the wastewater contains organic matter with a molecular weight less than 1 kDa, the activated carbon adsorption method can be directly used for rapid wastewater treatment.

[0061] Comparative Example 1 This comparative example provides a method for evaluating a sewage treatment process (in this comparative example, an aerated biological filter, BAF, is also used), specifically, a method for evaluating DOM degradation, wherein the 3 kDa ultrafiltration membrane used in Example 1 is replaced with a 5 kDa ultrafiltration membrane, comprising the following steps: Step 1, take 150mL of water before and after the sewage treatment process, record them as influent and produced water, respectively, use 0.45μm filter membrane to filter the water, and the filtrates obtained are recorded as influent 1 and produced water 1 respectively; Step 2, taking the influent 1 and the produced water 1 after preliminary filtration and performing graded nitrogen pressure filtration ultrafiltration respectively; in this embodiment, 10kDa, 5kDa, and 1kDa ultrafiltration membranes are used in sequence, and the pressure range of the pressure filtration is controlled within 0.1-0.22MPa; Specifically, 100 ml of influent 1 is filtered using a 10 kDa ultrafiltration membrane to obtain influent 2, at which the molecular weight of DOM in influent 2 is less than 10 kDa; 70 ml of influent 2 was filtered using a 5 kDa ultrafiltration membrane to obtain influent 3. At this time, the molecular weight of DOM in influent 3 was less than 5 kDa; 50 ml of influent 3 was taken and filtered using a 1 kDa ultrafiltration membrane to obtain influent 4. At this time, the molecular weight of DOM in influent 4 was less than 1 kDa; Similarly, produced water 2, produced water 3, and produced water 4 are obtained in sequence.

[0062] Step 3, performing three-dimensional fluorescence scanning on the filtrate after the preliminary filtration in step 1 and the filtrate of each level after the graded filtration in step 2; Taking influent 1 as an example, the specific steps of three-dimensional fluorescence scanning are described as follows: 3 mL of influent 1 is taken, and the absorbance of the filtrate at 254 nm is measured using an ultraviolet-visible spectrophotometer. In this embodiment, the absorbance of the influent 1 is greater than 0.1, so the influent 1 is diluted 6 times, and the absorbance of the influent 1 is less than 0.1. Then 1 mL of the sample is taken for three-dimensional fluorescence scanning, and the scanning parameters are: excitation wavelength 200-500 nm, emission wavelength 220-550 nm, step length 2 nm, scanning speed 12000 nm / min, slit width 5 nm, and three-dimensional fluorescence data of the first filtrate of the influent is obtained; The three-dimensional fluorescence data of influent 2 (dilution factor of 6), influent 3 (dilution factor of 4), influent 4 (dilution factor of 4), and produced water 1 (dilution factor of 5), produced water 2 (dilution factor of 5), produced water 3 (dilution factor of 4), and produced water 4 (dilution factor of 4) were obtained in sequence; At the same time, in addition to performing a three-dimensional fluorescence scan on the filtrate, this comparative example also requires performing a three-dimensional fluorescence scan on the pure water to obtain three-dimensional fluorescence data of the pure water.

[0063] Step 4: Before performing parallel factor analysis, the three-dimensional fluorescence data is pre-processed, including background subtraction, Rayleigh scattering and Raman scattering removal; The background subtraction is to subtract the fluorescence data of pure water from each three-dimensional fluorescence data obtained in step 3; then the three-dimensional fluorescence data after background subtraction is interpolated using the Delaunay triangulation method in the prior art to remove Rayleigh scattering and Raman scattering, avoid the influence of the two scatterings on subsequent data, and obtain the three-dimensional fluorescence data after pre-processing; Then, based on the trilinear theory in the prior art, parallel factor analysis was performed on the pre-processed three-dimensional fluorescence data to obtain the spectra of the tryptophan-like, tyrosine-like, and humus-like components in this comparative example (if the sample is diluted, the fluorescence intensity should be amplified according to the dilution multiple); The excitation wavelength of the tryptophan-like fluorescence peak center is 220-280nm, and the emission wavelength is 330-380nm; the excitation wavelength of the tyrosine-like fluorescence peak center is 250-300nm, and the emission wavelength is 300-350nm; the excitation wavelength of the humic acid-like fluorescence peak center is 228-250nm and 310-326nm, and the emission wavelength is 410-436nm; Specifically, the fluorescence intensities corresponding to different substances in each sample in this comparative example are shown in Table 7: Table 7 Fluorescence intensity of different substances in each sample in Comparative Example 1

[0064] From Table 7, the corresponding fluorescence intensity of each sample in different molecular diameter or molecular weight range can be calculated. The specific calculation method is to subtract the fluorescence intensity of tryptophan-like in influent 1 (passed through 0.45 μm filter membrane) from the fluorescence intensity of tryptophan-like in influent 2 (passed through 10 kDa ultrafiltration membrane), subtract the fluorescence intensity of tryptophan-like in influent 2 (passed through 10 kDa ultrafiltration membrane) from the fluorescence intensity of tryptophan-like in influent 3 (passed through 5 kDa ultrafiltration membrane), and subtract the fluorescence intensity of tryptophan-like in influent 3 (passed through 5 kDa ultrafiltration membrane) from the fluorescence intensity of tryptophan-like in influent 4 (passed through 1 kDa ultrafiltration membrane). The intensity can be used to obtain the fluorescence intensity of tryptophan-like molecules with molecular weight or molecular diameter of 10kDa-0.45μm, 5kDa-10kDa, 1kDa-5kDa in the influent water; similarly, the fluorescence intensity of tyrosine-like and humic acid-like molecules of 10kDa-0.45μm, 5kDa-10kDa, 1kDa-5kDa in the influent water can be obtained; similarly, the fluorescence intensity of tryptophan-like, tyrosine-like and humic acid-like molecules of 10kDa-0.45μm, 5kDa-10kDa, 1kDa-5kDa in the produced water can be obtained.

[0065] The calculation results are shown in Table 8: Table 8 Fluorescence intensity of samples in different molecular diameters or molecular weight ranges

[0066] Step 5: The fluorescence intensities of tryptophan-like, tyrosine-like, and humus-like substances after primary filtration are recorded as F A1 、F A2 、F A3 The fluorescence intensity of tryptophan-like and tyrosine-like after passing through 5kDa ultrafiltration membrane in graded filtration was recorded as F B1 、F B2 , according to the following formula: , Calculate the content of refractory dissolved organic matter in the influent of sewage treatment process: The content of difficult-to-degrade organic matter in the influent water = [1-(20.1+34.2) / (46.6+27.2+50.7) ] × 100% = 56%.

[0067] The soluble COD of the sewage in the influent of Example 1 and Comparative Example 1 was detected by using the detection method for COD value in the national standard GB11914-1989. The detection result showed that the soluble COD in the sewage influent was 60 mg / L, and the soluble COD in the influent after biological treatment was 39 mg / L. The actual refractory soluble organic matter content of the sewage obtained by the biological method was 39 / 60×100%=65%. The data detected according to the national standard is closer to the detection result of 63% in Example 1. That is, relative to Example 1, this comparative example replaces the 3kDa ultrafiltration membrane in Example 1 with a 5kDa ultrafiltration membrane, and its refractory soluble organic matter content is significantly lower than the actual value, and the effect is not as good as that of Example 1. It is impossible to accurately obtain the result of the refractory soluble organic matter content. Therefore, in this evaluation method, it is necessary to specifically use a 3kDa ultrafiltration membrane for graded filtration.

[0068] Comparative Example 2 This comparative example provides an evaluation method for a sewage treatment process (Fenton oxidation method is used in this comparative example) relative to Example 2, but does not use graded ultrafiltration relative to Example 2; specifically, it is an evaluation method for DOM degradation, comprising the following steps: Step 1, take 150mL of water before and after the sewage treatment process, record them as influent and produced water, respectively, use 0.45μm filter membrane to preliminarily filter the water, and the obtained filtrates are recorded as influent 1 and produced water 1 respectively; directly perform subsequent analysis on influent 1 and produced water 1; Step 2, performing three-dimensional fluorescence scanning on the filtrate after preliminary filtration in step 1; Taking influent 1 as an example, the specific steps of three-dimensional fluorescence scanning are described as follows: 3 mL of influent 1 is taken, and the absorbance of the filtrate at 254 nm is measured using an ultraviolet-visible spectrophotometer. In this comparative example, the absorbance of the influent 1 is greater than 0.1, so the influent 1 is diluted 6 times, and the absorbance of the influent 1 is less than 0.1. Then 1 mL of the sample is taken for three-dimensional fluorescence scanning, and the scanning parameters are: excitation wavelength 200-500 nm, emission wavelength 220-550 nm, step length 2 nm, scanning speed 12000 nm / min, slit width 5 nm, and three-dimensional fluorescence data of the first filtrate of the influent is obtained; The three-dimensional fluorescence data of produced water 1 (diluted 5 times) were obtained in turn; At the same time, in addition to performing a three-dimensional fluorescence scan on the filtrate, this comparative example also requires performing a three-dimensional fluorescence scan on the pure water to obtain three-dimensional fluorescence data of the pure water.

[0069] Step 3: Before performing parallel factor analysis, the three-dimensional fluorescence data is pre-processed, including background subtraction, Rayleigh scattering and Raman scattering removal; The background subtraction is to subtract the fluorescence data of pure water from each three-dimensional fluorescence data obtained in step 2; then the three-dimensional fluorescence data after background subtraction is interpolated using the Delaunay triangulation method in the prior art to remove Rayleigh scattering and Raman scattering, avoid the influence of the two scatterings on subsequent data, and obtain the three-dimensional fluorescence data after pre-processing; Then, based on the trilinear theory in the prior art, parallel factor analysis is performed on the pre-processed three-dimensional fluorescence data to obtain the spectra of the tryptophan-like, tyrosine-like, and humus-like components in this embodiment (if the sample is diluted, the fluorescence intensity should be amplified according to the dilution multiple); The excitation wavelength of the tryptophan-like fluorescence peak center is 220-280nm, and the emission wavelength is 330-380nm; the excitation wavelength of the tyrosine-like fluorescence peak center is 250-300nm, and the emission wavelength is 300-350nm; the excitation wavelength of the humic acid-like fluorescence peak center is 228-250nm and 310-326nm, and the emission wavelength is 410-436nm; Specifically, the fluorescence intensities corresponding to different substances in each sample in this comparative example are shown in Table 9: Table 9 Fluorescence intensity of different substances in each sample in Comparative Example 2

[0070] Table 9 cannot calculate the corresponding fluorescence intensity of each sample in different molecular diameters or molecular weight ranges, so it is impossible to obtain the accurate content of difficult-to-degrade soluble organic matter in the sewage treatment process. It can only be roughly obtained that the Fenton oxidation sewage oxidation treatment process has basically no degradation effect on humic acid-like substances, which is also quite different from the refined conclusions in Example 2, and it is impossible to provide reasonable treatment process guidance for specific sewage conditions.

[0071] From the examples and comparative examples, it can be seen that since various sewage treatment processes have different removal effects in DOM removal, different sewage treatment processes can be matched.

[0072] At the same time, according to the evaluation method of the specific sewage treatment process of the present invention, a database of sewage treatment results of different treatment processes or different regions can be established. In the process of establishment and improvement, the database can provide fast, reliable and clear guidance value for selecting which sewage treatment process to use or how to match and combine the sewage treatment processes to achieve the optimal treatment effect, thereby reducing the trial and error costs in the sewage treatment process.

[0073] It should be understood that the present invention is not limited to what has been described above and shown in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for evaluating a sewage treatment process, characterized in that: The steps include: Step 1: Take the water quality before and after the sewage treatment process and perform preliminary filtration on the water quality; Step 2, performing graded ultrafiltration on the filtrate after preliminary filtration; Step 3, performing three-dimensional fluorescence scanning on the filtrate after the preliminary filtration in step 1 and the filtrate of each level after the graded filtration in step 2; Step 4, performing parallel factor analysis on the three-dimensional fluorescence data in step 3, obtaining the fluorescence intensity corresponding to each substance in DOM, and obtaining the degradation of DOM by the sewage treatment process; The various substances in the DOM include tryptophan-like substances, tyrosine-like substances, and humus-like substances; Step 5: The fluorescence intensities of tryptophan-like, tyrosine-like, and humus-like substances after primary filtration are recorded as F A1 、F A2 、F A3 The fluorescence intensity of tryptophan-like and tyrosine-like after any stage of filtration in the graded filtration is recorded as F B1 、F B2 , the content of difficult-to-degrade dissolved organic matter in the sewage treatment process is calculated according to the following formula: 。 2. The method for evaluating a sewage treatment process according to claim 1, characterized in that: The preliminary filtration described in step 1 uses a 0.45 μm filter membrane.

3. The method for evaluating a sewage treatment process according to claim 1, characterized in that: In step 2, the order of graded filtration is 10 kDa, 3 kDa, and 1 kDa ultrafiltration membranes.

4. The method for evaluating a sewage treatment process according to claim 3, characterized in that: Nitrogen pressure filtration is used in the graded filtration of step 2.

5. The method for evaluating a sewage treatment process according to claim 4, characterized in that: The pressure of the pressure filtration is 0.1-0.22 MPa.

6. The method for evaluating a sewage treatment process according to claim 1, characterized in that: The scanning parameters of the three-dimensional fluorescence scanning in step 3 are: excitation wavelength 200-500 nm, emission wavelength 220-550 nm, step length 2 nm, scanning speed 12000 nm / min, and slit width 5 nm.

7. The method for evaluating a sewage treatment process according to claim 6, characterized in that: In addition to performing three-dimensional fluorescence scanning on the filtrate, it is also necessary to perform three-dimensional fluorescence scanning on the pure water to obtain three-dimensional fluorescence data of the pure water.

8. The method for evaluating a sewage treatment process according to claim 5, characterized in that: Before performing parallel factor analysis in step 3, the three-dimensional fluorescence data is pre-processed, including background subtraction, removal of Rayleigh scattering and Raman scattering.

9. The method for evaluating a sewage treatment process according to claim 8, characterized in that: The background subtraction is to subtract the three-dimensional fluorescence data of pure water from the three-dimensional fluorescence data of the filtrate; The three-dimensional fluorescence data after background subtraction were interpolated using the Delaunay triangulation method to remove Rayleigh scattering and Raman scattering; Parallel factor analysis was performed on the descattered three-dimensional fluorescence data using trilinear theory.

10. A sewage treatment process evaluation database established using the sewage treatment process evaluation method according to any one of claims 1 to 9.

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