Methods for assessing biodegradability of dissolved organic nitrogen in wastewater

Abstract

To provide a method for evaluating biodegradability of soluble organic nitrogen in sewage and its application.SOLUTION: A method includes the following steps of: (1) concentrating the soluble organic nitrogen contained in the sewage sample; (2) determining the molecular composition of the soluble organic nitrogen contained in the sewage sample; (3) calculating the sum of the relative intensities of the soluble organic nitrogen molecules with a hydrogen-carbon ratio of at least 1.5 in the step (2); (4) and evaluating the biodegradability of soluble organic nitrogen in sewage using the value obtained in the step (3). This method is fast, easy to operate, and provides information on molecular structure that can be used to guide the selection of sewage treatment processes that contain organic nitrogen.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the field of sewage treatment. Specifically, the present invention relates to a method for evaluating the biodegradability of dissolved organic nitrogen in sewage. By law Get involved. [Background technology]

[0002] In industrial production processes such as leather tanning, printing and pharmaceuticals Leave Sewage containing organic nitrogen is generated, but the organic nitrogen contaminants in sewage are difficult to treat because they have complex components and high concentrations. Sewage biological treatment technology is the main process for treating sewage containing organic nitrogen because it requires little consumption and is low cost. but The dissolved organic nitrogen contained in the wastewater is but Total nitrogen included is now standard Reached This is one of the important reasons why biological wastewater is not but The dissolved organic matter contained in the sewage water can lead to membrane fouling and nitrogen-based disinfection by-products, which can seriously affect the quality of sewage. Subsequent Therefore, it is necessary to select a sewage treatment process that contains organic nitrogen. To The biodegradability of soluble organic nitrogen in sewage must be taken into consideration.

[0003] Conventionally, the biodegradability of soluble organic nitrogen has been mainly measured by the static culture method, in which the sludge mixture is mixed with the sewage sample as an inoculum and placed in an incubator for culture. Leave The consumed soluble organic nitrogen is the total soluble organic nitrogen concentration. To The percentage of the total amount of the sludge mixture is expressed as the percentage of the total amount of the sludge mixture. It is necessary to During the culture process Leave It requires appropriate conditions such as temperature, nutrient elements and pH, and the concentration of organic nitrogen is difficult to measure. Overall, this method requires a long incubation period (14-28 days) and high requirements for operation technology, so it can be used to quickly determine the biodegradability of dissolved organic nitrogen contained in sewage samples. of Unattainable and short term inIt is difficult to determine the appropriate treatment process.

[0004] The Chinese invention patent with application number CN201210325754.5 is but The present invention discloses a method and apparatus for studying the biological availability of dissolved organic nitrogen, including soluble organic nitrogen. The apparatus mainly includes a filtration device, a soluble organic nitrogen extraction device, and an algae growth system, and is an integrated device, but since it requires a filtration membrane, a temperature sensor, a light sensor, and an online pH and soluble organic nitrogen monitoring device, it is expensive, and the biological availability of dissolved organic nitrogen is determined by measuring the change in nitrogen content of water samples in the algae growth system, so the test process is complicated and requires a long period of time. DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0005] The present invention is a sewage but A rapid and simple method for evaluating the biodegradability of dissolved organic nitrogen, including but The purpose of this standard is to provide technical assistance in the evaluation of the biodegradability of dissolved organic nitrogen, including soluble organic nitrogen, and in the selection of appropriate treatment processes. [Means for solving the problem]

[0006] The specific steps of the evaluation method for the biodegradability of dissolved organic nitrogen in sewage are as follows:

[0007] (1) The dissolved organic nitrogen contained in the sewage sample concentrated do

[0008] (2) Measure the molecular composition of soluble organic nitrogen contained in sewage samples.

[0009] (3) The sum of the relative intensities of soluble organic nitrogen molecules with a hydrogen-carbon ratio of at least 1.5 in step (2) Calculate TIFF0007624730000001.tif723.

[0010] (4) TIFF0007624730000002.tif618 of Numerical evaluation of the biodegradability of soluble organic nitrogen in wastewater.

[0011] Further, according to the above solution, step (1) is to concentrate the dissolved organic nitrogen contained in the sewage sample through a solid phase extraction column, which includes column activation, sample loading, column rinsing, column drying and column elution. During the column activation process, methanol equivalent to 2-3 times the column volume, hydrochloric acid equivalent to 3-5 times the column volume, and the like are sequentially added to the column. Acidification with The flow rate of the sewage sample was controlled at 0.5-3.0 mL / min during the sample insertion process, and hydrochloric acid equivalent to 3-6 times the column volume was used during the column rinsing process. Acidification with In the column drying process, nitrogen gas is blown into the solid phase extraction column until it is dry. In the column elution process, methanol equivalent to 1 to 3 times the volume of the column is used and the flow rate is controlled to 0.5 to 1.5 mL / min. Before the solid phase extraction, the sewage sample must be filtered through a 0.45 μm filter membrane and adjusted to pH = 2 with hydrochloric acid. Before the analysis and detection, the soluble organic compounds in the concentrated sample must be removed. nitrogen The concentration of the element must be 50 mg / L.

[0012] Further, according to the above solution, in the above step (2), the molecular components of the dissolved organic nitrogen contained in the sewage sample are measured by Fourier transform ion cyclotron resonance mass spectrometry, which is a super-high resolution mass spectrum and has high accuracy in measuring the molecular components of the dissolved organic nitrogen.

[0013] Furthermore, the parameters of the instrument for the test analysis by the Fourier transform ion cyclotron resonance mass spectrometry were as follows: scan mode: negative ion / full spectrum scan; ionization source: electrospray (ESI) ionization source; sample input speed: 120-180 μL / h; polarization voltage: 2.5-3.0 kV; ion accumulation time: 0.001-0.3 s; mass collection range: 150-1000 Da; number of sampling points: 2-4 M; and number of overlapping mass spectrum scans: 200-500 to improve the signal-to-noise ratio. in be.

[0014] Further, according to the above solution, in step (3), TIFF0007624730000003.tif618 of Until the calculation To It is necessary to pre-process the data for the response peaks of the dissolved organic nitrogen molecules of each sewage sample and to standardize the data for the intensity of the response peaks of the pre-processed organic nitrogen molecules.

[0015] As for the data preprocessing, the signal-to-noise ratio was set to 6 or more in the data processing program. in The response peak of a certain organic nitrogen is screened, and calculations are performed based on its mass-to-charge ratio to match it with a molecular formula.

[0016] The molecular formula must satisfy the following conditions: mass error range is ±1 ppm, the number of carbon (C) atoms is 2 to 50, and the number of hydrogen (H) atoms is 2 to 120. in Yes, and TIFF0007624730000004.tif625, with 0 to 30 oxygen (O) atoms in Yes, and TIFF0007624730000005.tif718, with 1 to 4 nitrogen (N) atoms in can be, TIFF0007624730000006.tif59 in and N / C is up to 0.5 and the number of sulfur (S) atoms is 0 to 2 in can be, TIFF0007624730000007.tif58 in and S / C is up to 0.2, and the number of phosphorus (P) atoms is 0 to 2 in with P / C up to 0.1, and TIFF0007624730000008.tif722, and the number of equivalent double bonds (DBE) is an integer and is at least 0 in Yes, and the formula is The file is TIFF0007624730000009.tif1355.

[0017] After data preprocessing, the intensity of the total response peak of each sample is equal, which makes it convenient to compare between samples and obtain a more accurate molecular composition of dissolved organic nitrogen in the wastewater.

[0018] As a standardization process for the above data, TIFF0007624730000010.tif1321 is used to calculate the relative intensity (RIi) of each response peak. in , I i is the absolute intensity of the response peak for each molecular formula, TIFF0007624730000011.tif58 is the sum of the absolute intensities of the response peaks of all molecular formulas in this sample.

[0019] The data are normalized to ensure that the total response peak intensity for each sample is equal, allowing convenient comparison between samples.

[0020] Furthermore, according to the above solution, in step (4) The method for evaluating the biodegradability of soluble organic nitrogen in sewage using numerical values ​​from TIFF0007624730000012.tif618 is as follows:

[0021] The hydrogen-carbon ratio in the sewage sample is at least 1.5. R Sum of relative intensities of soluble organic nitrogen formulas TIFF0007624730000013.tif723 is 45% or more inIn some cases, the biodegradability of soluble organic nitrogen in wastewater is good.

[0022] This percentage is 35-45% in In some cases, the biodegradation of dissolved organic nitrogen in sewage is possible, and this rate is between 20 and 35%. in In some cases, the dissolved organic nitrogen in sewage is difficult to biodegrade and the proportion of this is less than 20%. in In some cases, the soluble organic nitrogen present in wastewater is not suitable for biodegradation.

[0023] The present invention also provides the application of the evaluation method for the biodegradability of dissolved organic nitrogen in sewage. When the method is applied to the treatment process of sewage containing organic nitrogen, the specific results are as follows:

[0024] TIFF0007624730000014.tif618 is 45% or more in In some cases, the soluble organic nitrogen in sewage has good biodegradability, so it is better to treat sewage containing organic nitrogen by biological methods.

[0025] TIFF0007624730000015.tif618 is 35-45% in In some cases, soluble organic nitrogen in sewage is biodegradable, so it is advisable to treat sewage containing organic nitrogen using bioaugmentation methods.

[0026] TIFF0007624730000016.tif618 is 20-35% in In some cases, the soluble organic nitrogen in sewage is difficult to biodegrade, so it is better to improve the biodegradability of the soluble organic nitrogen in the sewage through physical and chemical pretreatment before treating it with biological or bioaugmentation methods.

[0027] TIFF0007624730000017.tif618 is less than 20% in In some cases, the dissolved organic nitrogen in sewage is not suitable for biodegradation, so it is better to treat the sewage containing organic nitrogen by chemical or physical and chemical methods.

[0028] Furthermore, TIFF0007624730000018.tif618 is 20-35% in In some cases, the physical and chemical treatment methods include chemical oxidation and electrocatalysis. Effect of the Invention

[0029] (1) The method for evaluating the biodegradability of dissolved organic nitrogen in sewage according to the present invention is fast and simple, with a short test period, and the entire test and analysis can be completed within one day. Within This can be completed without the need for microbial culture.

[0030] (2) The method for evaluating the biodegradability of organic nitrogen according to the present invention can be used to guide the selection of sewage treatment processes containing organic nitrogen, and can also provide information on the molecular structure of soluble organic nitrogen in sewage. [Brief description of the drawings]

[0031] [Figure 1] 1 is a flow chart for guiding the selection of a treatment process based on the biodegradability of dissolved organic nitrogen in sewage according to the present invention. [Diagram 2] 1 is a graph showing the ratio of the sum of relative intensities of dissolved organic nitrogen molecules having a hydrogen-carbon ratio of at least 1.5 in different types of sewage samples measured by the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The present invention will now be described in more detail in conjunction with specific examples, but the present invention is not limited thereto. EXAMPLES

[0033] When evaluating the biodegradability of soluble organic nitrogen in the wastewater samples from a printing company, the average COD concentration of the wastewater is 527mg / L, the average total nitrogen concentration is 74mg / L, the average organic nitrogen concentration is 45mg / L, and the average total phosphorus concentration is 3.8mg / L. The details of the evaluation steps are as follows:

[0034] (1) The soluble organic nitrogen contained in the printing wastewater sample is concentrated using a solid-phase extraction column. The concentration process includes column activation, sample insertion, column rinsing, column drying and column elution. During the column activation process, methanol equivalent to twice the column volume, hydrochloric acid equivalent to four times the column volume, and so on are sequentially added. Acidification with The solid-phase extraction column was activated with ultrapure water (pH = 2) that had been purified by filtration. During the sample loading process, the flow rate of the sewage sample was controlled at 3.0 mL / min. During the column rinsing process, hydrochloric acid equivalent to four times the volume of the column was used. Acidification with The solid-phase extraction column was rinsed with ultrapure water (pH = 2) that had been dried, and nitrogen gas was blown into the solid-phase extraction column until it was dry. In the column elution process, the column was eluted with methanol equivalent to twice the column volume at a flow rate of 1.0 mL / min. The soluble organic compounds in the sample were extracted so that their concentration was 50 mg / L or more before analysis and detection. nitrogen Concentrate the element.

[0035] (2) The molecular components of soluble organic nitrogen contained in the printing sewage sample were measured by Fourier transform ion cyclotron resonance mass spectrometry. The instrument parameters were: scan mode: negative ion full spectrum scan, ionization source: electrospray (ESI) ionization source, sample insertion speed: 140 μL / h, polarization voltage: 2.5 kV, ion accumulation time: 0.006 s, mass collection range: 150-800 Da, number of sampling points: 4M, and number of mass spectrum scan overlaps: 300.

[0036] (3) Perform data preprocessing for the response peaks of soluble organic nitrogen molecules in the printing sewage sample and standardize the data for the response peak intensities of the organic nitrogen molecules that have been subjected to the data preprocessing.

[0037] A signal-to-noise ratio of 6 or higher was obtained using the data processing program. in The response peak of a certain organic nitrogen is screened, and its mass-to-charge ratio is calculated to match it with the molecular formula. The molecular formula satisfies the following conditions: mass error range is ±1 ppm, the number of carbon (C) atoms is 2 to 50, and the number of hydrogen (H) atoms is 2 to 120. inYes, and TIFF0007624730000019.tif625, with 0 to 30 oxygen (O) atoms in Yes, and TIFF0007624730000020.tif718, and the number of nitrogen (N) atoms is 1 to 4 in can be, TIFF0007624730000021.tif59 in and N / C is up to 0.5 and the number of sulfur (S) atoms is 0 to 2 in can be, TIFF0007624730000022.tif58 in and S / C is up to 0.2, and the number of phosphorus atoms (P) is 0 to 2 in with P / C up to 0.1, and TIFF0007624730000023.tif722 in and the number of equivalent double bonds (DBE) is an integer and is at least 0 in Yes, and the formula is The file is TIFF0007624730000024.tif1355.

[0038] To standardize the above data, the formula TIFF0007624730000025.tif1321 is used to calculate the relative intensity (RIi) of each response peak. in , I i is the absolute intensity of the response peak for each molecular formula, TIFF0007624730000026.tif58 is the sum of the absolute intensities of the response peaks of all molecular formulas in this sample.

[0039] Next, the sum of the relative intensities of dissolved organic nitrogen molecules with a hydrogen-carbon ratio of at least 1.5 in the sewage sample Calculate TIFF0007624730000027.tif723.

[0040] (4) The sum of the relative intensities of soluble organic nitrogen molecules with a hydrogen-carbon ratio of at least 1.5 in the printed wastewater sample. TIFF0007624730000028.tif723 is 24.3% (Figure 2), so sewage but The soluble organic nitrogen contained therein is difficult to biodegrade.

[0041] The amount of soluble organic nitrogen contained in this printing wastewater sample was TIFF0007624730000029.tif618 is 20-35% in Therefore, following the recommendations in Figure 1, physical and chemical treatment should be carried out, followed by biological or bioaugmentation treatment. 5 Select the appropriate process according to the COD value. EXAMPLES

[0042] A sample of wastewater from a pharmaceutical factory but When the biodegradability evaluation was performed for the dissolved organic nitrogen contained in the samples, the average COD concentration of the samples was 2668 mg / L, the average total nitrogen concentration was 574 mg / L, the average organic nitrogen concentration was 305 mg / L, and the average total phosphorus concentration was 6.1 mg / L. The details of the evaluation steps are as follows:

[0043] (1) Concentrate the soluble organic nitrogen contained in pharmaceutical wastewater samples using a solid-phase extraction column. The concentration process includes column activation, sample insertion, column rinsing, column drying, and column elution. During the column activation process, methanol equivalent to two times the column volume, hydrochloric acid equivalent to six times the column volume, and so on are sequentially added. Acidification with The solid-phase extraction column was activated with ultrapure water (pH = 2) that had been purified by filtration. The flow rate of the sewage sample was controlled at 2.0 mL / min during the sample loading process, and hydrochloric acid equivalent to six times the column volume was used during the column rinsing process. Acidification with The solid-phase extraction column was rinsed with ultrapure water (pH = 2) that had been dried, and nitrogen gas was blown into the solid-phase extraction column until it was dry. In the column elution process, the column was eluted with methanol equivalent to twice the column volume at a flow rate of 0.5 mL / min. The soluble organic compounds in the sample were extracted so that their concentration was 50 mg / L or more before analysis and detection. nitrogen Concentrate the element.

[0044] (2) The molecular components of soluble organic nitrogen in pharmaceutical wastewater samples were measured by Fourier transform ion cyclotron resonance mass spectrometry. The instrument parameters were: scan mode: negative ion full spectrum scan; ionization source: electrospray (ESI) ionization source; sample loading rate: 180 μL / h; polarization voltage: 3.0 kV; ion accumulation time: 0.3 s; mass collection range: 200–900 Da. in The number of sampling points is 4M, and the number of mass spectrum scans is 500.

[0045] (3) Data preprocessing is performed for the response peaks of soluble organic nitrogen molecules in pharmaceutical sewage samples, and data standardization is performed for the response peak intensities of the organic nitrogen molecules that have been subjected to data preprocessing.

[0046] A signal-to-noise ratio of 6 or higher was obtained using the data processing program. in The response peak of a certain organic nitrogen is screened, and its mass-to-charge ratio is calculated to match it with the molecular formula. The molecular formula satisfies the following conditions: mass error range is ±1 ppm, the number of carbon (C) atoms is 2 to 50, and the number of hydrogen (H) atoms is 2 to 120. in Yes, and TIFF0007624730000030.tif625, with 0 to 30 oxygen (O) atoms in Yes, and TIFF0007624730000031.tif718, and the number of nitrogen (N) atoms is 1 to 4 in can be, TIFF0007624730000032.tif59 in and N / C is up to 0.5 and the number of sulfur (S) atoms is 0 to 2 in can be, TIFF0007624730000033.tif58 in and S / C is up to 0.2, and the number of phosphorus atoms (P) is 0 to 2 in with P / C up to 0.1, and TIFF0007624730000034.tif722 inand the number of equivalent double bonds (DBE) is an integer and is at least 0 in Yes, and the formula is The file is TIFF0007624730000035.tif1355.

[0047] To standardize the above data, the formula TIFF0007624730000036.tif1321 is used to calculate the relative intensity (RIi) of each response peak. in , I i is the absolute intensity of the response peak for each molecular formula, TIFF0007624730000037.tif58 is the sum of the absolute intensities of the response peaks of all molecular formulas in this sample. Next, the sum of the relative intensities of dissolved organic nitrogen molecules with a hydrogen-carbon ratio of at least 1.5 in the sewage sample. Calculate TIFF0007624730000038.tif723.

[0048] (4) The sum of the relative intensities of dissolved organic nitrogen molecules with a hydrogen-to-carbon ratio of at least 1.5 in this pharmaceutical wastewater sample. TIFF0007624730000039.tif723 is 41.2% (Figure 2), so sewage but The dissolved organic nitrogen contained therein is biodegradable.

[0049] The amount of dissolved organic nitrogen contained in this pharmaceutical wastewater sample was TIFF0007624730000040.tif618 is 35-45% in Therefore, we will treat the wastewater using the bioaugmentation method recommended in Figure 1, and 5 Select the appropriate process according to the COD value. EXAMPLES

[0050] The wastewater from a tannery was sampled butThe biodegradability of dissolved organic nitrogen contained in the wastewater samples was evaluated, and the average COD concentration was 3067 mg / L, the average total nitrogen concentration was 708 mg / L, the average organic nitrogen concentration was 368 mg / L, and the average total phosphorus concentration was 5.6 mg / L. The details of the evaluation steps are as follows:

[0051] (1) The soluble organic nitrogen contained in the tannery wastewater sample was concentrated using a solid-phase extraction column. The concentration process included column activation, sample insertion, column rinsing, column drying, and column elution. During the column activation process, methanol equivalent to three times the column volume, hydrochloric acid equivalent to five times the column volume, and the column was then eluted. Acidification with The solid-phase extraction column was activated with ultrapure water (pH = 2) that had been purified by filtration. The flow rate of the sewage sample was controlled at 1.5 mL / min during the sample loading process, and hydrochloric acid equivalent to 5 times the column volume was used during the column rinsing process. Acidification with The solid-phase extraction column was rinsed with ultrapure water (pH = 2) that had been dried, and nitrogen gas was blown into the solid-phase extraction column until it was dry. In the column elution process, the column was eluted with methanol equivalent to twice the column volume at a flow rate of 1.5 mL / min. The soluble organic compounds in the sample were extracted so that their concentration was 50 mg / L or more before analysis and detection. nitrogen Concentrate the element.

[0052] (2) The molecular components of soluble organic nitrogen in the tannery wastewater samples were measured by Fourier transform ion cyclotron resonance mass spectrometry. The instrument parameters were: scan mode: negative ion full spectrum scan; ionization source: electrospray (ESI) ionization source; sample loading rate: 120 μL / h; polarization voltage: 2.5 kV; ion accumulation time: 0.03 s; mass collection range: 150–1000 Da. in The number of sampling points is 2M, and the number of mass spectrum scans is 380.

[0053] (3) Data preprocessing is performed for the response peaks of soluble organic nitrogen molecules in the tannery sewage sample, and data standardization is performed for the response peak intensities of the organic nitrogen molecules that have been subjected to the data preprocessing.

[0054] A signal-to-noise ratio of 6 or higher was obtained using the data processing program. in The response peak of a certain organic nitrogen is screened, and its mass-to-charge ratio is calculated to match it with the molecular formula. The molecular formula satisfies the following conditions: mass error range is ±1 ppm, the number of carbon (C) atoms is 2 to 50, and the number of hydrogen (H) atoms is 2 to 120. in Yes, and TIFF0007624730000041.tif625, with 0 to 30 oxygen (O) atoms in Yes, and TIFF0007624730000042.tif718, and the number of nitrogen (N) atoms is 1 to 4 in can be, TIFF0007624730000043.tif59 in and N / C is up to 0.5 and the number of sulfur (S) atoms is 0 to 2 in can be, TIFF0007624730000044.tif58 in and S / C is up to 0.2, and the number of phosphorus atoms (P) is 0 to 2 in with P / C up to 0.1, and TIFF0007624730000045.tif722 in and the number of equivalent double bonds (DBE) is an integer and is at least 0 in Yes, and the formula is The file is TIFF0007624730000046.tif1355.

[0055] To standardize the above data, the formula Calculate the relative intensity (RIi) of each response peak in TIFF0007624730000047.tif1321. in , I i is the absolute intensity of the response peak for each molecular formula, TIFF0007624730000048.tif58 is the sum of the absolute intensities of the response peaks of all molecular formulas in this sample.

[0056] Next, the sum of the relative intensities of dissolved organic nitrogen molecules with a hydrogen-carbon ratio of at least 1.5 in the sewage sample Calculate TIFF0007624730000049.tif723.

[0057] (4) The sum of the relative intensities of dissolved organic nitrogen molecules in the tannery wastewater sample that have a hydrogen-to-carbon ratio of at least 1.5. TIFF0007624730000050.tif723 is 38.7% (Figure 2), so sewage but Contains soluble organic nitrogen is biodegradable.

[0058] The soluble organic nitrogen content of this tannery wastewater sample was TIFF0007624730000051.tif618 35-45% Therefore, according to the recommendation in Fig. 1 The treatment is carried out using bioaugmentation methods. Sewage BOD 5 Select the appropriate process according to the COD value.

Claims

1. A method for evaluating the biodegradability of dissolved organic nitrogen in sewage, comprising the steps of: (1) concentrating soluble organic nitrogen contained in a sewage sample to obtain a sewage sample having concentrated soluble organic nitrogen; (2) measuring the sewage sample in which soluble organic nitrogen has been concentrated in step (1), identifying the soluble organic nitrogen contained in the sewage sample on a molecular basis, and measuring the absolute intensity of the peak of the identified molecule, thereby measuring the molecular components of the soluble organic nitrogen contained in the sewage sample; (3) The sum of the relative intensities of soluble organic nitrogen molecules having a hydrogen-to-carbon ratio of at least 1.5 to the sum of the absolute intensities of all soluble organic nitrogen molecules, including soluble organic nitrogen molecules having a hydrogen-to-carbon ratio not at least 1.5 in step (2). and calculating （４） and evaluating the biodegradability of dissolved organic nitrogen in sewage using the value of Including, In the step (2), the molecular components of dissolved organic nitrogen contained in the sewage sample are measured by Fourier transform ion cyclotron resonance mass spectrometry; The method for evaluating the biodegradability of dissolved organic nitrogen in sewage is characterized in that the parameters of the instrument for performing the test analysis by the Fourier transform ion cyclotron resonance mass spectrometry are as follows: scan mode: negative ion / full spectrum scan; ionization source: electrospray ionization source; sample introduction speed: 120-180 μL / h; polarization voltage: 2.5-3.0 kV; ion accumulation time: 0.001-0.3 s; mass collection range: 150-1000 Da; number of sampling points: 2-4 M;

2. The step (1) comprises concentrating the soluble organic nitrogen contained in the sewage sample using a solid-phase extraction column; In step (4) The method for evaluating the biodegradability of dissolved organic nitrogen in sewage using the value of If the ratio is 45% or more, the biodegradability of dissolved organic nitrogen in the sewage is good, When the nitrogen content is between 35 and 45%, the dissolved organic nitrogen in the sewage is biodegradable. When the concentration is between 20% and 35%, the soluble organic nitrogen in the sewage is difficult to biodegrade.

2. The method for evaluating the biodegradability of soluble organic nitrogen in sewage according to claim 1, wherein the soluble organic nitrogen in the sewage is deemed not suitable for biodegradation if the soluble organic nitrogen content is 20% or less.

3. The method for evaluating the biodegradability of soluble organic nitrogen in sewage as described in Claim 2, characterized in that the solid phase extraction column is a styrene divinylbenzene polymer cartridge.

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