A method for evaluating the biodegradability of wastewater from the printing and dyeing industry based on three-dimensional fluorescence spectroscopy

Abstract

The present invention discloses a method for evaluating the biodegradability of wastewater from the printing and dyeing industry based on three-dimensional fluorescence spectroscopy, and belongs to the technical field of water quality detection. It includes three-dimensional fluorescence spectroscopy data acquisition and processing and the establishment of a printing and dyeing wastewater biodegradability evaluation model. Industry wastewaters often have similar spectral characteristics due to similar production processes. The present invention improves the potential connection between the spectral characteristics of industry wastewater and biodegradability through correlation analysis between three-dimensional fluorescence data and BOD5 / COD, and establishes a method for evaluating the biodegradability of wastewater based on three-dimensional fluorescence spectroscopy analysis. The entire detection process of this method does not require additional reagents and is not restricted by bacterial species. Not only can the test results be obtained within half an hour, but the changes in water quality components can also be analyzed based on the fluorescence spectrum to guide engineering applications.

Description

Technical Field

[0001] The invention belongs to the technical field of water quality detection, and specifically relates to a method for evaluating the biodegradability of wastewater in the printing and dyeing industry based on three-dimensional fluorescence spectroscopy. Background Art

[0002] At present, sewage treatment technology is still dominated by biochemical treatment. When biological treatment is used, the biodegradability of wastewater must be considered. BOD5 / COD is the main indicator for measuring the biodegradability of wastewater. The higher the BOD5 / COD value, the better the biodegradability. It is generally believed that when BOD5 / COD ≥ 0.45, the biodegradability of wastewater is good; when BOD5 / COD ≥ 0.3, the wastewater is biodegradable; when BOD5 / COD ≤ 0.3, the wastewater is difficult to biodegrade.

[0003] BOD5 stands for five-day biochemical oxygen demand, which refers to the amount of dissolved oxygen required for the aerobic microorganisms in the water body to decompose organic matter in the water into inorganic matter at 20°C during the oxidation process within 5 days. It is usually determined by the dilution inoculation method, which is cumbersome and time-consuming. For industrial wastewater containing biological toxicity, the test results of inoculating untamed sludge often have large errors. COD stands for chemical oxygen demand, which refers to the oxygen equivalent of substances (generally organic matter) that can be oxidized by strong oxidants in wastewater, effluent from wastewater treatment plants and contaminated water. It is usually determined by the rapid digestion method. The COD determination and digestion of samples also requires a certain amount of time, and the reagents required in the test process involve concentrated sulfuric acid, mercuric sulfate, and silver sulfate. Not only is the operation process dangerous, but it also causes secondary pollution to the environment. In addition, for industrial wastewater containing halogens such as bromine and chlorine, the COD detection value will be significantly higher, resulting in a low BOD5 / COD. Therefore, for industrial wastewater, especially wastewater containing halogens and biological toxicity, BOD5 / COD cannot accurately reflect the biodegradability of water.

[0004] In the prior art, patent CN107192800A discloses a method for evaluating the toxicity and biodegradability of chemical wastewater, which provides a method for evaluating the biodegradability and toxicity of chemical wastewater by relative oxygen consumption. The detection time can be shortened to less than 20 minutes, solving the problem that BOD5 cannot evaluate the toxicity of wastewater. However, it still requires inoculation of sludge, which requires heavy and drying of the sludge, and preparation of an activated sludge mixture. It requires long-term aeration and cultivation of the sludge, and the entire inoculation process is relatively cumbersome.

[0005] The three-dimensional fluorescence spectrum is a matrix spectrum characterized by the three-dimensional coordinates of excitation wavelength, emission wavelength, and fluorescence intensity. Due to the different properties of different substances, the light they emit is also different. EEM technology has been widely used in the analysis of dissolved organic matter components in water and sewage tracing. Patent CN112082979A discloses a rapid detection method for petroleum hydrocarbon organic matter in groundwater, and proposes to take multiple groundwater samples in the polluted area, perform three-dimensional fluorescence spectrum detection, calculate specific spectrum parameters, and obtain a fitting equation. According to the obtained fitting equation, the content of petroleum hydrocarbon organic matter in the groundwater sample to be tested is determined. Patent CN112198144A discloses a method and system for rapid sewage tracing, and proposes to perform water quality data detection and three-dimensional fluorescence spectrum analysis on historical water samples collected from the outlet nodes of each enterprise in the monitoring basin, and use the entropy weight method to calculate the new matrix of the three-dimensional fluorescence spectrum as the water quality characteristics of the water sample, and then enter the name and geographical location of the enterprise, pipe network, and river into the database as the label of the water quality characteristics of the enterprise to form the water quality unique information of each enterprise. The water quality characteristics of the newly measured water sample are calculated for similarity with all the water quality snapshot information in the database. Finally, the water quality snapshot information with the highest similarity is the pollution source, thus achieving the purpose of sewage tracing.

[0006] The above patents make full use of the fluorescent "fingerprint" of water samples to realize the analysis and traceability of organic matter in wastewater. This patent applies the fluorescent "fingerprint" to biodegradability analysis, which can solve the problem of cumbersome and time-consuming existing biodegradability assessment and can quickly assess the biodegradability of wastewater. Summary of the invention

[0007] The purpose of the present invention is to provide a method for evaluating the biodegradability of wastewater in the printing and dyeing industry based on three-dimensional fluorescence spectroscopy.

[0008] The technical solution to achieve the purpose of the present invention is: a method for evaluating the biodegradability of wastewater in the printing and dyeing industry based on three-dimensional fluorescence spectroscopy, including three-dimensional fluorescence spectroscopy data collection and processing, and the establishment of a biodegradability evaluation model for printing and dyeing wastewater, wherein:

[0009] The three-dimensional fluorescence spectrum data collection and processing includes: filtering multiple printing and dyeing wastewater samples collected from the same printing and dyeing factory through a 0.45um filter membrane, naming them as known water samples, using a fluorescence spectrophotometer to perform three-dimensional fluorescence spectrum measurement on deionized water blank water samples and known water samples, and uniformly numbering them to form a data set; importing the data set into MATLAB software, uniformly deducting the three-dimensional fluorescence spectrum data of the deionized water blank water samples, performing corresponding trimming and smoothing corrections, and obtaining the three-dimensional fluorescence spectrum data of the known water samples, dividing the three-dimensional fluorescence spectrum data into 5 regions, and using the regional integration method to calculate the integral proportion P of each region of the known water sample i , i is I, Ⅱ,..., Ⅴ;

[0010] The establishment of the biodegradability assessment model for printing and dyeing wastewater includes: using national standards to measure the COD and BOD5 of known water samples, calculating its BOD5 / COD, and analyzing the P of known water samples through data analysis software. i The correlation between BOD5 / COD and the area with strong correlation is calculated based on the correlation. i The value is used as the ordinate and BOD5 / COD is used as the abscissa to obtain the P value of the strongly correlated area of ​​the known water sample. i The fitting function of BOD5 / COD is used to determine the P of the strongly correlated area of ​​the water sample to be evaluated. i The functional relationship with BOD5 / COD is used to obtain the biodegradability of the water sample to be evaluated.

[0011] Furthermore, the three-dimensional fluorescence spectrum data is divided into five zones: zone I is tryptophan-like, with an excitation wavelength of 200-250 nm and an emission wavelength of 280-325 nm; zone II is tyrosine-like, with an excitation wavelength of 200-250 nm and an emission wavelength of 325-375 nm; zone III is fulvic acid-like, with an excitation wavelength of 200-250 nm and an emission wavelength of 375-550 nm; zone IV is a soluble microbial degradation product protein-like, with an excitation wavelength of >250 nm and an emission wavelength of 280-375 nm; zone V is humic acid-like, with an excitation wavelength of >250 nm and an emission wavelength of 375-550 nm.

[0012] Furthermore, the three-dimensional fluorescence spectrum data is divided into five matrix lists according to area I, area II, area III, area IV, and area V. It is known that the regional integral corresponding to each area of ​​the water sample is C I , C Ⅱ , C Ⅲ , C Ⅳ , C Ⅴ , C i For the regional integral of a certain area of ​​the known water sample, calculate the integral proportion P of each area of ​​the known water sample i :

[0013]

[0014] Furthermore, the fluorescence spectrophotometer is a Hitachi F-4700FL fluorescence spectrophotometer, and the excitation wavelength Ex of the fluorescence spectrophotometer ranges from 200 to 500 nm, and the emission wavelength Em ranges from 250 to 600 nm.

[0015] Furthermore, the P of known water samples was analyzed by data analysis software. i The correlation between BOD5 / COD and the data analysis software is selected from any one of Origin, MATLAB, SPSS and Excel.

[0016] Furthermore, the CORREL formula in Excel software was used to analyze the P of known water samples. i The correlation between BOD5 / COD and the area with strong correlation is calculated based on the correlation. i The value is taken as the ordinate y, and BOD5 / COD is taken as the abscissa x, and the P of the strongly correlated area of ​​the known water sample is obtained. i Fitting function with BOD5 / COD:

[0017] y=Ax+B

[0018] Where A and B are constants.

[0019] Furthermore, according to the P of the strong correlation area of ​​the known water sample i The fitting function of BOD5 / COD is used to obtain the P value of the strongly correlated area of ​​the water sample to be evaluated. i The functional relationship with BOD5 / COD is used to calculate the BOD5 / COD of the water sample to be evaluated. According to BOD5 / COD≥0.45, the water sample has good biodegradability; BOD5 / COD≥0.3, the water sample is biodegradable; BOD5 / COD≤0.3, the water sample is difficult to biodegrade, and the biodegradability of the water sample to be evaluated is obtained.

[0020] Furthermore, it is known that the number of water samples taken is no less than 3.

[0021] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in the following aspects: the present invention can quickly correspond the biodegradability of water samples according to their fluorescent "fingerprint" characteristics; the entire detection process does not require additional reagents and is not restricted by bacterial species; not only can the test results be obtained within half an hour, but the changes in water quality components can also be analyzed based on the fluorescence spectrum to guide engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the fluorescence spectrum of a water sample with poor biochemical properties in a printing and dyeing factory.

[0023] Figure 2 This is the fluorescence spectrum of a water sample with good biochemical properties in a printing and dyeing factory.

[0024] Figure 3 Evaluation factor P for the example Ⅲ Linear correlation equation with BOD5 / COD. DETAILED DESCRIPTION

[0025] In order to make the purpose, advantages and effects of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and in combination with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0026] Industrial wastewater often has similar spectral characteristics due to similar production processes. Taking the biodegradability assessment of wastewater from the printing and dyeing industry as an example, the present invention improves the potential connection between the spectral characteristics of industrial wastewater and biodegradability through correlation analysis between three-dimensional fluorescence data and BOD5 / COD, and establishes a method for assessing the biodegradability of wastewater based on three-dimensional fluorescence spectral analysis.

[0027] The method for evaluating the biodegradability of wastewater from the printing and dyeing industry based on three-dimensional fluorescence spectroscopy in this embodiment is as follows:

[0028] 1. Three-dimensional fluorescence spectral data acquisition and processing

[0029] Firstly, 5 water samples were collected from a printing and dyeing factory. The 5 water samples were filtered through a 0.45um filter membrane and named as known water sample 1, ..., known water sample 5 respectively. Hitachi F-4700FL fluorescence spectrophotometer was used to measure the three-dimensional fluorescence spectra of the blank water sample and the 5 known water samples. The excitation light source was a 150W xenon arc lamp, the excitation wavelength Ex range was 200-500nm, the emission wavelength Em range was 250-600nm, the scanning bandwidth was 5nm, the slit width was 5nm, the scanning speed was 2400nm / min, the PMT voltage was 600V, and they were uniformly numbered to form a data set. The data set was imported into MATLAB software, the three-dimensional fluorescence spectrum data of the deionized water blank sample was uniformly subtracted, and the corresponding trimming and smoothing correction were performed to obtain the data set. The three-dimensional fluorescence spectrum data of the five known water samples were obtained and divided into five zones. Zone I is tryptophan-like substances, with an excitation wavelength of 200-250nm and an emission wavelength of 280-325nm; Zone II is tyrosine-like substances, with an excitation wavelength of 200-250nm and an emission wavelength of 325-375nm; Zone III is fulvic acid-like substances, with an excitation wavelength of 200-250nm and an emission wavelength of 375-550nm; Zone IV is protein-like substances such as soluble microbial degradation products, with an excitation wavelength of >250nm and an emission wavelength of 280-375nm; Zone V is humic acid-like substances, with an excitation wavelength of >250nm and an emission wavelength of 375-550nm. Finally, the three-dimensional fluorescence spectrum data of the five known water samples were imported into the Origin drawing software (such as Figure 1 , as shown in 2), the three-dimensional fluorescence spectrum data is divided into 5 matrix lists according to area I, area II, area III, area IV, and area V. It is known that the regional integral corresponding to each area of ​​the water sample is C I , C Ⅱ , C Ⅲ , C Ⅳ , C Ⅴ , C i For the regional integral of a certain area of ​​the known water sample, calculate the integral proportion P of each area of ​​the known water sample i :

[0030]

[0031] The regional integration method was used to calculate the integral proportions P of the known water samples in zone I, zone II, zone III, zone IV, and zone V. I , P Ⅱ , P Ⅲ , P Ⅳ , P Ⅴ (%), the data are shown in Table 1.

[0032] 2: Establishment of biodegradability assessment model for printing and dyeing wastewater

[0033] The COD and BOD5 of the above five known water samples (known water sample 1, ..., known water sample 5) were measured by national standards, and the BOD5 / COD of the known water samples was calculated. The data are shown in Table 1. The P of the known water samples was analyzed by data analysis software. I , P Ⅱ , P Ⅲ , P Ⅳ , P Ⅴ The correlation between BOD5 / COD and the P of a region with strong correlation was selected. i The value is used as the ordinate and BOD5 / COD is used as the abscissa to obtain the P value of the strongly correlated area of ​​the known water sample. i Fitting function with BOD5 / COD:

[0034] y=Ax+B

[0035] In the fitting function, A and B are constants, which change with the characteristics of water samples from different printing and dyeing plants. The A and B values ​​of water samples from the same printing and dyeing plant are fixed.

[0036] Table 1 Water sample P of a printing and dyeing factory I , P Ⅱ , P Ⅲ , P Ⅳ , P Ⅴ BOD5 / COD data sheet

[0037] <![CDATA[P I ]]> <![CDATA[P Ⅱ ]]> <![CDATA[P Ⅲ ]]> <![CDATA[P Ⅳ ]]> <![CDATA[P Ⅴ ]]> <![CDATA[BOD5 / COD]]> Known water sample 1 14.04 52.57 11.69 15.69 5.99 0.29 Known water sample 2 12.86 50.98 9.57 19.09 7.49 0.43 Known water sample 3 16.08 55.26 7.17 17.33 4.15 0.50 Known water sample 4 14.52 52.54 7.02 19.95 5.96 0.51 Known water sample 5 17.59 56.37 5.28 17.58 3.17 0.65

[0038] In this implementation, the CORREL formula in Excel is used to analyze the P in Table 1. I , P Ⅱ , P Ⅲ , P Ⅳ , P Ⅴ The correlation between BOD5 / COD and the P value in zone III was obtained. Ⅲ The correlation with BOD5 / COD is -0.9798, indicating that PⅢ It has the best negative correlation with BOD5 / COD, that is, P in zone III Ⅲ is the integral proportion of the strongly correlated area P i Therefore, this embodiment selects the P of the strongly correlated III zone Ⅲ The value is used as the ordinate y, and BOD5 / COD is used as the abscissa x to draw a scatter plot (such as Figure 3 The P value of the strongly correlated region (region III) of the known water samples was obtained by fitting the curve. Ⅲ The fitting function with BOD5 / COD is y=-18.688x+17.043.

[0039] Water samples 6 and 7 from the same printing and dyeing factory at different time periods were taken as water samples 6 and 7 to be evaluated, and three-dimensional fluorescence spectrum data were collected and processed respectively. The P values ​​in the strongly correlated area of ​​water samples 6 and 7, i.e., area III, were calculated. Ⅲ The values ​​12.97 and 2.57 are used as y values, respectively, and substituted into the above fitting function y = -18.688x + 17.043, and the x values, that is, the BOD5 / COD values, are obtained as 0.22 and 0.77 respectively. According to BOD5 / COD ≥ 0.45, the biodegradability is good; BOD5 / COD ≥ 0.3, it is biodegradable; BOD5 / COD ≤ 0.3, it is difficult to biodegrade, and an assessment is conducted. Water sample 6 to be evaluated is a water sample that is difficult to biodegrade, and water sample 7 to be evaluated is a water sample with good biodegradability. After actual measurement, the actual BOD5 / COD value of water sample 6 to be evaluated is 0.27, and the actual BOD5 / COD value of water sample 7 to be evaluated is 0.72. The evaluation results are basically consistent with the measured data of the water samples.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for evaluating the biodegradability of wastewater from the printing and dyeing industry based on three-dimensional fluorescence spectroscopy, characterized in that: It includes three-dimensional fluorescence spectrum data collection and processing and the establishment of a biodegradability assessment model for printing and dyeing wastewater, among which: The three-dimensional fluorescence spectrum data collection and processing includes: filtering multiple printing and dyeing wastewater samples collected from the same printing and dyeing factory through a 0.45um filter membrane, naming them as known water samples, using a fluorescence spectrophotometer to perform three-dimensional fluorescence spectrum measurement on deionized water blank water samples and known water samples, and uniformly numbering them to form a data set; importing the data set into MATLAB software, uniformly deducting the three-dimensional fluorescence spectrum data of the deionized water blank water sample, performing corresponding trimming and smoothing corrections, and obtaining the three-dimensional fluorescence spectrum data of the known water sample, dividing the three-dimensional fluorescence spectrum data into 5 regions, and using the regional integration method to calculate the integral proportion P of each region of the known water sample i , i is I, Ⅱ,..., Ⅴ; The establishment of the biodegradability assessment model for printing and dyeing wastewater includes: using national standards to measure the COD and BOD5 of known water samples, calculating its BOD5 / COD, and analyzing the P of known water samples through data analysis software. i The correlation between BOD5 / COD and the area with strong correlation is calculated based on the correlation. i The value is used as the ordinate and BOD5 / COD is used as the abscissa to obtain the P value of the strongly correlated area of ​​the known water sample. i The fitting function of BOD5 / COD is used to determine the P of the strongly correlated area of ​​the water sample to be evaluated. i The functional relationship with BOD5 / COD is used to obtain the biodegradability of the water sample to be evaluated.

2. The method according to claim 1, characterized in that The three-dimensional fluorescence spectrum data is divided into five zones: zone I is tryptophan-like, with an excitation wavelength of 200-250 nm and an emission wavelength of 280-325 nm; zone II is tyrosine-like, with an excitation wavelength of 200-250 nm and an emission wavelength of 325-375 nm; zone III is fulvic acid-like, with an excitation wavelength of 200-250 nm and an emission wavelength of 375-550 nm; zone IV is a soluble microbial degradation product protein-like, with an excitation wavelength of >250 nm and an emission wavelength of 280-375 nm; zone V is humic acid-like, with an excitation wavelength of >250 nm and an emission wavelength of 375-550 nm.

3. The method according to claim 1, characterized in that The three-dimensional fluorescence spectrum data is divided into five matrix lists according to area I, area II, area III, area IV, and area V. The regional integral corresponding to each area of ​​the known water sample is C I , C Ⅱ , C Ⅲ , C Ⅳ , C Ⅴ , C i For the regional integral of a certain area of ​​the known water sample, calculate the integral proportion P of each area of ​​the known water sample i :

4. The method according to claim 1, characterized in that The fluorescence spectrophotometer is a Hitachi F-4700FL fluorescence spectrophotometer, and the excitation wavelength Ex of the fluorescence spectrophotometer ranges from 200 to 500 nm, and the emission wavelength Em ranges from 250 to 600 nm.

5. The method according to claim 1, characterized in that Analyze the P of known water samples by data analysis software i The correlation between BOD5 / COD and the data analysis software is selected from any one of Origin, MATLAB, SPSS and Excel.

6. The method according to claim 1, characterized in that Analyze the P of known water samples by using the CORREL formula in Excel software i The correlation between BOD5 / COD and the area with strong correlation is calculated based on the correlation. i The value is taken as the ordinate y, and BOD5 / COD is taken as the abscissa x, and the P of the strongly correlated area of ​​the known water sample is obtained. i Fitting function with BOD5 / COD: y=Ax+B Where A and B are constants.

7. The method according to claim 1, characterized in that According to the P of the strong correlation area of ​​the known water samples i The fitting function of BOD5 / COD is used to obtain the P value of the strongly correlated area of ​​the water sample to be evaluated. i The functional relationship with BOD5 / COD is used to calculate the BOD5 / COD of the water sample to be evaluated. According to BOD5 / COD≥0.45, the water sample has good biodegradability; BOD5 / COD≥0.3, the water sample is biodegradable; BOD5 / COD≤0.3, the water sample is difficult to biodegrade, and the biodegradability of the water sample to be evaluated is obtained.

8. The method according to claim 1, characterized in that The number of known water samples shall not be less than 3.

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