Method for comparative evaluation of biotoxicity of industrial wastewater before and after treatment

Abstract

The invention belongs to the technical field of resources and environment, and particularly relates to a method for comparative evaluation of biotoxicity of industrial wastewater before and after treatment. In order to solve the problems of single selected toxicity endpoint, lack of toxicity comparison and the like in current industrial wastewater toxicity evaluation, the method comprises the following steps: calculating a toxicity sensitivity index and a toxicity sensitivity comprehensive index through physicochemical index detection and toxicology prediction calculation, and selecting a toxicity evaluation endpoint and a model organism which are most sensitive to the wastewater; calculating importance coefficients of different toxicity end points, determining selected biological experiment modes and indexes, and establishing a biological toxicity evaluation system of the wastewater before treatment; the biotoxicity evaluation index of the treated wastewater is substituted into the system, the wastewater dilution multiple before treatment is used for representing the wastewater biotoxicity decline rate before and after treatment, the decline rate reflects the treatment effect of the wastewater comprehensive biotoxicity before and after treatment of the industrial wastewater in the workshop section, and the comprehensive evaluation of the industrial wastewater treatment effect in the workshop section can be completed.

Description

Technical Field

[0001] The invention belongs to the technical field of resources and environment, and in particular relates to a comparative evaluation method for biological toxicity of industrial wastewater before and after treatment. Background Art

[0002] As a global challenge, preventing and controlling water ecosystem pollution is a key link in deepening the battle against pollution and promoting the comprehensive green transformation of the economy and society. Industrial wastewater plays an important role in preventing and controlling water ecosystem pollution due to its huge discharge volume, complex chemical composition, and high difficulty in detection and treatment. Whether the toxic effects of industrial wastewater on the ecological environment and humans can be scientifically evaluated is related to the efficiency of wastewater treatment.

[0003] The business scope of industrial enterprises covers ore mining, metal smelting, material processing, and equipment manufacturing. The amount of industrial wastewater discharged is huge, and the pollutants in the wastewater are of many types and high concentrations. There is an urgent need to develop scientific and efficient wastewater biological toxicity evaluation methods. At present, wastewater toxicity is generally evaluated by testing physical and chemical indicators and comparing them with emission standards, ignoring the possible synergistic or antagonistic effects between pollutants. The WET assessment method adopted by the United States, Japan and other countries exposes standardized aquatic organisms to wastewater samples with different dilution multiples to evaluate the acute and chronic toxicity of wastewater. The DTA assessment method improved by the United Kingdom, Australia and other countries on this basis not only identifies the adverse effects of wastewater, but also stipulates the degree of reduction of the impact, and can carry out corresponding treatment according to the test results to achieve an acceptable level of environmental quality. The WEA assessment method adopted by EU countries such as Germany also focuses on the persistence and bioaccumulation of wastewater pollutants, and more comprehensively evaluates the environmental risks of wastewater. However, these methods have the common problems of selecting a single toxicity endpoint, lacking toxicity comparison, and not being able to comprehensively evaluate the specific toxic effects of organisms such as reproduction, development, and genetics before and after wastewater treatment. Summary of the invention

[0004] In view of the above problems, the present invention provides a comparative evaluation method for the biological toxicity of industrial wastewater before and after treatment. The method focuses on the production process of industrial parks and the current status of industrial wastewater discharge. On the basis of sufficient preliminary investigation, a method for comparatively calculating the biological toxicity reduction rate of industrial wastewater in each stage before and after treatment is proposed. The method is suitable for a comprehensive biological toxicity evaluation system that combines "physical and chemical properties-toxicity prediction-biological experiments" of different industrial wastewaters, and is used to evaluate the changes in comprehensive biological toxicity of industrial wastewater before and after treatment, so as to provide technical support for the efficient and safe utilization of water resources.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A comparative evaluation method for the biological toxicity of industrial wastewater before and after treatment comprises the following steps:

[0007] Step 1, establishing a process evaluation model, including: analyzing the physical and chemical indicators of industrial wastewater before process treatment, selecting model organisms and toxicity endpoints based on the toxicity sensitivity index and the toxicity sensitivity comprehensive index, and determining the importance coefficient of the selected toxicity endpoint, biological toxicity experiments and detection indicators, and then establishing a biological toxicity evaluation system;

[0008] Step 2, evaluating the biological toxicity of the treated industrial wastewater, including: collecting the treated industrial wastewater from the work section, selecting the model organisms selected in step 1 and the determined biological experimental method, measuring the detection indicators of different toxicity endpoints of the treated wastewater, and substituting the measured detection indicators into the biological toxicity evaluation system established in step 1 to obtain the biological toxicity of the treated industrial wastewater equivalent to the dilution multiple before treatment, and then obtaining the reduction rate of the biological toxicity of the industrial wastewater before and after treatment, that is, completing the comparative evaluation of the biological toxicity of the industrial wastewater before and after treatment.

[0009] Furthermore, in step 1, a work section evaluation model is established, specifically:

[0010] Step 1.1. Select model organism and toxicity endpoint

[0011] Step 1.1.1, based on the production process and research data of the workshop, sampling, screening the types of pollutants in the industrial wastewater samples before treatment and quantitatively testing their concentrations;

[0012] Step 1.1.2, using the toxicity database and toxicity prediction software, predict the toxicity of different types of pollutants screened out in the industrial wastewater samples before treatment, and obtain the toxicity prediction value of each pollutant at different toxicity endpoints for different model organisms (Chlorella, Daphnia magna, zebrafish, etc.). If the actual quantitative detection concentration of different types of pollutants in step 1.1.1 is greater than its toxicity prediction value, it can be considered to be toxic at the toxicity endpoint;

[0013] Step 1.1.3, calculate the importance coefficient of different types of pollutants, the formula is as follows:

[0014]

[0015] In the formula, i is the type of pollutant, n is the number of pollutants whose actual quantitative detection concentration is greater than the predicted toxicity value, and Y i The toxicity prediction values ​​of different pollutants whose actual quantitative detection concentration is greater than the toxicity prediction value under the same model organism species and the same toxicity endpoint;

[0016] Step 1.1.4, calculate the toxicity sensitivity index of a single model organism at different toxicity endpoints, the formula is as follows:

[0017]

[0018] In the formula, i is the type of pollutant, a is the type of model organism, b is the toxicity endpoint, and X i The actual concentration values ​​of different pollutants detected under the same model organism species and the same toxicity endpoint, where the actual quantitative detection concentration is greater than the toxicity prediction value;

[0019] Step 1.1.5, arrange the toxicity sensitivity index of a single model organism at different toxicity endpoints from large to small, select the three toxicity endpoints with the largest toxicity sensitivity index for each model organism, and calculate the comprehensive toxicity sensitivity index of different model organisms. The formula is as follows:

[0020]

[0021] In the formula, i is different toxicity endpoints, a is the model organism species, b is i is the i-th toxicity endpoint selected, TSI is the toxicity endpoint b i Industrial wastewater toxicity sensitivity index;

[0022] Step 1.1.6, arranging the toxicity sensitivity comprehensive indexes of different model organisms from large to small, selecting the model organism with the largest toxicity sensitivity comprehensive index (the model organism most sensitive to this type of wastewater) for biological toxicity experiments, and the three toxicity endpoints with the largest toxicity sensitivity comprehensive index corresponding to it;

[0023] Step 1.2: Determine the importance coefficient, biological toxicity test and detection index of the selected toxicity endpoint

[0024] Step 1.2.1, calculate the importance coefficients of different toxicity endpoints based on the calculation results of steps 1.1.4 and 1.1.5, the formula is as follows:

[0025]

[0026] Where b i is the selected ith toxicity endpoint, TSI(a,b i ) and TSCI(a) are the calculation results of step 1.1.4 and step 1.1.5 respectively;

[0027] Step 1.2.2, based on the three selected toxicity endpoints and in combination with relevant biological experimental data, determine the biological toxicity experiment and detection index that best reflects the toxic effect under the toxicity endpoint;

[0028] Step 1.3, Establish a biological toxicity evaluation system

[0029] Step 1.3.1, dilute the untreated industrial wastewater to 10, 50, 100, 500, and 1000 times, and form six experimental groups and one blank control group together with the undiluted industrial wastewater, select the model organism selected in step 1.1.6 and the biological toxicity experiment determined in step 1.2.2, and measure the detection indicators of different toxicity endpoints in each group;

[0030] Step 1.3.2, based on the results of the biological toxicity experiment, calculate the toxicity evaluation index of each group of model organisms. The formula is as follows:

[0031]

[0032] In the formula, m is the experimental group, i is the selected different toxicity endpoints, The toxicity endpoints of each experimental group and the blank control group were b i , b 0 The corresponding detection indicators are: is the ith toxicity endpoint b i The importance coefficient of

[0033] Step 1.3.3, with different dilution multiples as the horizontal axis x and the corresponding toxicity evaluation index as the vertical axis y, the fitting curve y(x) is prepared.

[0034] Furthermore, the types of pollutants in step 1.1.1 include inorganic pollutants and organic pollutants.

[0035] Furthermore, in step 2, the biological toxicity of the treated industrial wastewater is evaluated, specifically:

[0036] Step 2.1 Biological toxicity test of treated industrial wastewater

[0037] Step 2.1.1, collecting wastewater samples after treatment in the process section, selecting the model organism determined in step 1.1.6 and the biological toxicity experiment determined in step 1.2.2, and measuring the detection indicators of different toxicity endpoints of the treated wastewater;

[0038] Step 2.1.2, based on the results of the biological toxicity test, calculate the toxicity evaluation index of the treated industrial wastewater according to the formula in step 1.3.2;

[0039] Step 2.2, Characterization of biological toxicity of treated industrial wastewater

[0040] Step 2.2.1, use the toxicity evaluation index calculated in step 2.1.2 as the ordinate y, substitute it into the curve fitted in step 1.3.3, and calculate the corresponding abscissa x, that is, the biological toxicity of the industrial wastewater after treatment is equivalent to the dilution multiple before treatment;

[0041] Step 2.2.2, based on the results of step 2.2.1, calculate the reduction rate of biological toxicity of industrial wastewater before and after treatment. The reduction rate is characterized by the dilution multiple of industrial wastewater before treatment. The formula is as follows:

[0042]

[0043] Where x is the dilution multiple of the biological toxicity of industrial wastewater after treatment compared to that before treatment.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] In response to the current problems in the biological toxicity evaluation of industrial wastewater, the present invention compares the advantages, disadvantages and practicality of different toxicity evaluation methods, detects pollutant concentrations according to the needs and current status of biological toxicity evaluation of industrial wastewater from a steel plant, adopts computational toxicology to establish a wastewater biological toxicity prediction model, and combines biological experiments to evaluate the biological toxicity of industrial wastewater before and after treatment, achieving good results. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The process flow chart of the comparative evaluation method of the biological toxicity of industrial wastewater before and after treatment of the present invention is shown. DETAILED DESCRIPTION

[0047] In order to further illustrate the technical solution of the present invention, the present invention is further described below in conjunction with an example of a steel plant.

[0048] like Figure 1 As shown, a comparative evaluation method of biological toxicity of industrial wastewater before and after treatment in this example includes the following steps:

[0049] Step 1, establishing a process evaluation model, including: analyzing the physical and chemical indicators of industrial wastewater before process treatment, selecting model organisms and toxicity endpoints based on the toxicity sensitivity index and the toxicity sensitivity comprehensive index, and determining the importance coefficient of the selected toxicity endpoint, biological toxicity experiments and detection indicators, and then establishing a biological toxicity evaluation system;

[0050] Step 2, evaluating the biological toxicity of the treated industrial wastewater, including: collecting the treated industrial wastewater from the work section, selecting the model organisms selected in step 1 and the determined biological experimental method, measuring the detection indicators of different toxicity endpoints of the treated wastewater, and substituting the measured detection indicators into the biological toxicity evaluation system established in step 1 to obtain the biological toxicity of the treated industrial wastewater equivalent to the dilution multiple before treatment, and then obtaining the reduction rate of the biological toxicity of the industrial wastewater before and after treatment, that is, completing the comparative evaluation of the biological toxicity of the industrial wastewater before and after treatment.

[0051] More specifically, the work section evaluation model is established in step 1, specifically:

[0052] Step 1.1. Select model organism and toxicity endpoint

[0053] Step 1.1.1, based on the production category of the steel plant, combined with the production process of the section and research data, sampling, screening of pollutant types in the industrial wastewater samples before treatment and quantitative detection of their concentrations, the types of pollutants are shown in Table 1:

[0054] Table 1 Preliminary screening of pollutants in industrial wastewater from various sections of the steel plant

[0055]

[0056] According to the process flow chart, the discharge points of untreated wastewater in each work section were determined, and water samples were collected. Combined with the preliminary screening results, the concentrations of inorganic pollutants such as heavy metals and ammonia nitrogen were directly quantitatively detected according to the detection methods prescribed by the state. Organic pollutants were first qualitatively detected by high-throughput non-targeted methods such as gas chromatography-quadrupole time-of-flight mass spectrometry (GC-Q-TOF) and liquid chromatography-high resolution mass spectrometry (UPLC-LTQ-Orbitrap), and then quantitatively detected by methods such as gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS).

[0057] Step 1.1.2, using the toxicity database and toxicity prediction software, predict the toxicity of different types of pollutants screened out in the industrial wastewater samples before treatment, input the CAS number of the pollutant, and output the toxicity prediction value of each pollutant at different toxicity endpoints for different model organisms. The predicted value can be regarded as the critical value of whether the pollutant has a corresponding toxic effect on the model organism at this concentration. If the actual quantitative detection concentration of different types of pollutants in step 1.1.1 is greater than its toxicity prediction value, it can be regarded as toxic at this toxicity endpoint;

[0058] Toxicity databases include: the U.S. National Library of Medicine Compound Toxicity Database (ECONET), the U.S. National Institutes of Health Open Chemistry Database (ECOTOX), the U.S. National Toxicology Department website (NTP), etc. Toxicity prediction software includes: TEST, Toxtree, VEGA, etc. The recommended toxicity endpoints include: mutagenicity, acute toxicity, developmental toxicity, hepatotoxicity, reproductive toxicity, cardiotoxicity, neurotoxicity, and immunotoxicity. The corresponding relationship between the recommended toxicity endpoints and toxicity databases and prediction software is shown in Table 2:

[0059] Table 2 Toxicity databases and prediction software recommended for different toxicity endpoints

[0060]

[0061] When selecting a toxicity database and prediction software, the same database and prediction software should be used to predict all toxicity endpoints to reduce errors.

[0062] Step 1.1.3, calculate the importance coefficient of different types of pollutants based on the toxicity prediction value generated after entering the CAS number of the pollutant. The formula is as follows:

[0063]

[0064] In the formula, i is the type of pollutant, n is the number of pollutants whose actual quantitative detection concentration is greater than the predicted toxicity value, and Y i The toxicity prediction values ​​of different pollutants whose actual quantitative detection concentration is greater than the toxicity prediction value under the same model organism species and the same toxicity endpoint;

[0065] The importance coefficient λ of each screened pollutant is calculated, and λ represents the change in its toxic effect when the concentration of the pollutant changes by 1 unit.

[0066] Step 1.1.4, calculate the toxicity sensitivity index (TSI) of a single model organism (Chlorella, Daphnia magna, zebrafish) at different toxicity endpoints (mutagenicity, acute toxicity, developmental toxicity, hepatotoxicity, reproductive toxicity, cardiotoxicity, neurotoxicity, immunotoxicity, etc.) using the following formula:

[0067]

[0068] In the formula, i is the type of pollutant, a is the type of model organism, b is the toxicity endpoint, and X i The actual concentration values ​​of different pollutants detected under the same model organism species and the same toxicity endpoint, where the actual quantitative detection concentration is greater than the toxicity prediction value;

[0069] Step 1.1.5, arrange the TSI values ​​of single model organisms Chlorella, Daphnia magna, and zebrafish at different toxicity endpoints from large to small, select the three toxicity endpoints with the largest TSI values ​​for each model organism, which can be regarded as the three toxicity endpoints that the model organism is most sensitive to the biological toxic effects of wastewater, and substitute the TSI values ​​of different model organisms at the above three toxicity endpoints to calculate the comprehensive toxicity sensitivity index (TSCI value) of different model organisms. The formula is as follows:

[0070]

[0071] In the formula, i is different toxicity endpoints, a is the model organism species, b is i is the i-th toxicity endpoint selected, TSI is the toxicity endpoint b i Industrial wastewater toxicity sensitivity index;

[0072] In step 1.1.6, the TSCI values ​​of Chlorella, Daphnia magna, and zebrafish are arranged from large to small, and the model organism with the largest TSCI value is selected, which can be regarded as the model organism most sensitive to this type of wastewater, and then used in subsequent biological toxicity experiments, as well as the three toxicity endpoints with the largest TSCI values ​​corresponding to it, that is, the three toxicity endpoints that the model organism is most sensitive to this type of wastewater; through the above steps, the three most sensitive toxicity endpoints of the model organism that is most sensitive to all the major pollutants contained in the industrial wastewater of this section are actually selected.

[0073] Step 1.2: Determine the importance coefficient, biological toxicity test and detection index of the selected toxicity endpoint

[0074] Step 1.2.1, calculate the importance coefficient (K) of different toxicity endpoints based on the calculation results of steps 1.1.4 and 1.1.5, the formula is as follows:

[0075]

[0076] Where b i is the selected ith toxicity endpoint, TSI(a,b i ) and TSCI(a) are the calculation results of step 1.1.4 and step 1.15 respectively;

[0077] Step 1.2.2, based on the three selected toxicity endpoints and in combination with relevant biological experimental data, determine the biological toxicity experiment and detection index that best reflects the toxic effect under the toxicity endpoint. For each toxicity endpoint, 1 to 3 detection indicators can be selected as the average value. The results are shown in Table 3:

[0078] Table 3 Recommended biological experimental methods and detection indicators for different toxicity endpoints

[0079]

[0080]

[0081] Step 1.3, Establish a biological toxicity evaluation system

[0082] Step 1.3.1, according to the selected model organism, dilute the untreated industrial wastewater to 10, 50, 100, 500, 1000 times with culture medium or purified water, and form six experimental groups together with the undiluted industrial wastewater. The culture medium or purified water without wastewater is used as the blank control group. Select the model organism selected in step 1.1.6 and the biological toxicity experiment determined in step 1.2.2, and perform 24h or 96h exposure according to different toxicity endpoints, and then use the kit, microscope, flow cytometer, electronic balance, fluorescence real-time quantitative PCR technology and other means to measure the detection indicators of different toxicity endpoints in each group;

[0083] Step 1.3.2, compare the data obtained from the biological experiments corresponding to each toxicity endpoint of the test group and the blank control group. If the toxicity index data of the test group ≥ the toxicity index data of the blank control group, calculate the ratio of the test group / blank control group, otherwise calculate the ratio of the blank control group / test group, substitute the ratio P and the importance coefficient K corresponding to the different toxicity endpoints calculated in step 1.2.1, and calculate the toxicity evaluation index (TEI value) of each group of model organisms. The formula is as follows:

[0084]

[0085] In the formula, m is the experimental group, i is the selected different toxicity endpoints, The toxicity endpoints of each experimental group and the blank control group were b i , b 0 The corresponding detection indicators are: is the ith toxicity endpoint b i The importance coefficient of

[0086] Step 1.3.3, use different dilution multiples of 10, 50, 100, 500, 1000 as the horizontal axis x, and the TEI value corresponding to each dilution multiple as the vertical axis y, and fit the curve y(x).

[0087] The biological toxicity of the treated industrial wastewater is evaluated in step 2, specifically:

[0088] Step 2.1 Biological toxicity test of treated industrial wastewater

[0089] Step 2.1.1, according to the process flow chart, determine the discharge point of the wastewater in each section after treatment, collect the wastewater samples after treatment in the section, select the model organisms determined in step 1.1.6 and the biological toxicity experiment determined in step 1.2.2, and use the kit, microscope, flow cytometer, electronic balance, fluorescent real-time quantitative PCR technology and other means to measure the detection indicators of different toxic endpoints of the treated wastewater after 24h or 96h exposure;

[0090] Step 2.1.2, based on the results of the biological toxicity test, calculate the toxicity evaluation index of the treated industrial wastewater according to the formula in step 1.3.2;

[0091] Step 2.2, Characterization of biological toxicity of treated industrial wastewater

[0092] Step 2.2.1, use the toxicity evaluation index calculated in step 2.1.2 as the ordinate y, substitute it into the curve fitted in step 1.3.3, and calculate the corresponding abscissa x, that is, the biological toxicity of the industrial wastewater after treatment is equivalent to the dilution multiple before treatment;

[0093] Step 2.2.2, based on the results of step 2.2.1, calculate the reduction rate of biological toxicity of industrial wastewater before and after treatment. The reduction rate is characterized by the dilution multiple of industrial wastewater before treatment. The formula is as follows:

[0094]

[0095] Where x is the dilution multiple of the biological toxicity of the treated industrial wastewater before treatment. The decrease rate w reflects the treatment effect of the comprehensive biological toxicity of the industrial wastewater in this section before and after treatment, which can complete the comprehensive evaluation of the treatment effect of the industrial wastewater in the section.

[0096] The above shows and describes the main features and advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0097] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for comparative evaluation of the biological toxicity of industrial wastewater before and after treatment, characterized in that: The steps include: Step 1, establishing a process evaluation model, including: analyzing the physical and chemical indicators of industrial wastewater before process treatment, selecting model organisms and toxicity endpoints based on the toxicity sensitivity index and the toxicity sensitivity comprehensive index, and determining the importance coefficient of the selected toxicity endpoint, biological toxicity experiments and detection indicators, and then establishing a biological toxicity evaluation system; Step 2, evaluating the biological toxicity of the treated industrial wastewater, including: collecting the treated industrial wastewater from the work section, selecting the model organisms selected in step 1 and the determined biological experimental method, measuring the detection indicators of different toxicity endpoints of the treated wastewater, and substituting the measured detection indicators into the biological toxicity evaluation system established in step 1 to obtain the biological toxicity of the treated industrial wastewater equivalent to the dilution multiple before treatment, and then obtaining the reduction rate of the biological toxicity of the industrial wastewater before and after treatment, that is, completing the comparative evaluation of the biological toxicity of the industrial wastewater before and after treatment.

2. The method for comparative evaluation of biological toxicity of industrial wastewater before and after treatment according to claim 1, characterized in that: In step 1, a work section evaluation model is established, specifically: Step 1.

1. Select model organism and toxicity endpoint Step 1.1.1, based on the production process and research data of the workshop, sampling, screening the types of pollutants in the industrial wastewater samples before treatment and quantitatively testing their concentrations; Step 1.1.2, using the toxicity database and toxicity prediction software, predict the toxicity of different types of pollutants screened out in the industrial wastewater samples before treatment, and obtain the toxicity prediction value of each pollutant at different toxicity endpoints for different model organisms. If the actual quantitative detection concentration of different types of pollutants in step 1.1.1 is greater than its toxicity prediction value, it can be considered to be toxic at the toxicity endpoint; Step 1.1.3, calculate the importance coefficient of different types of pollutants, the formula is as follows: In the formula, i is the type of pollutant, n is the number of pollutants whose actual quantitative detection concentration is greater than the predicted toxicity value, and Y i The toxicity prediction values ​​of different pollutants whose actual quantitative detection concentration is greater than the toxicity prediction value under the same model organism species and the same toxicity endpoint; Step 1.1.4, calculate the toxicity sensitivity index of a single model organism at different toxicity endpoints, the formula is as follows: In the formula, i is the type of pollutant, a is the type of model organism, b is the toxicity endpoint, and X i The actual concentration values ​​of different pollutants detected under the same model organism species and the same toxicity endpoint, where the actual quantitative detection concentration is greater than the toxicity prediction value; Step 1.1.5, arrange the toxicity sensitivity index of a single model organism at different toxicity endpoints from large to small, select the three toxicity endpoints with the largest toxicity sensitivity index for each model organism, and calculate the comprehensive toxicity sensitivity index of different model organisms. The formula is as follows: In the formula, i is different toxicity endpoints, a is the model organism species, b is i is the i-th toxicity endpoint selected, TSI is the toxicity endpoint b i Industrial wastewater toxicity sensitivity index; Step 1.1.6, arranging the comprehensive toxicity sensitivity indexes of different model organisms from large to small, selecting the model organism with the largest comprehensive toxicity sensitivity index for biological toxicity experiments, and the three toxicity endpoints with the largest corresponding comprehensive toxicity sensitivity index; Step 1.2: Determine the importance coefficient, biological toxicity test and detection index of the selected toxicity endpoint Step 1.2.1, calculate the importance coefficients of different toxicity endpoints based on the calculation results of steps 1.1.4 and 1.1.5, the formula is as follows: Where b i is the selected ith toxicity endpoint, TSIa,b i and TSCI(a) are the calculation results of step 1.1.4 and step 1.1.5 respectively; Step 1.2.2, based on the three selected toxicity endpoints and in combination with relevant biological experimental data, determine the biological toxicity experiment and detection index that best reflects the toxic effect under the toxicity endpoint; Step 1.3, Establish a biological toxicity evaluation system Step 1.3.1, dilute the untreated industrial wastewater to 10, 50, 100, 500, and 1000 times, and form six experimental groups and one blank control group together with the undiluted industrial wastewater, select the model organism selected in step 1.1.6 and the biological toxicity experiment determined in step 1.2.2, and measure the detection indicators of different toxicity endpoints in each group; Step 1.3.2, based on the results of the biological toxicity experiment, calculate the toxicity evaluation index of each group of model organisms. The formula is as follows: In the formula, m is the experimental group, i is the selected different toxicity endpoints, The toxicity endpoints of each experimental group and the blank control group were b i , b0 corresponding detection index, is the ith toxicity endpoint b i The importance coefficient of Step 1.3.3, with different dilution multiples as the horizontal axis x and the corresponding toxicity evaluation index as the vertical axis y, the fitting curve y(x) is prepared.

3. The method for comparative evaluation of biological toxicity of industrial wastewater before and after treatment according to claim 2, characterized in that: The types of pollutants in step 1.1.1 include inorganic pollutants and organic pollutants.

4. The method for comparative evaluation of biological toxicity of industrial wastewater before and after treatment according to claim 2, characterized in that: The biological toxicity of the treated industrial wastewater is evaluated in step 2, specifically: Step 2.1 Biological toxicity test of treated industrial wastewater Step 2.1.1, collecting wastewater samples after treatment in the process section, selecting the model organism determined in step 1.1.6 and the biological toxicity experiment determined in step 1.2.2, and measuring the detection indicators of different toxicity endpoints of the treated wastewater; Step 2.1.2, based on the results of the biological toxicity test, calculate the toxicity evaluation index of the treated industrial wastewater according to the formula in step 1.3.2; Step 2.2, Characterization of biological toxicity of treated industrial wastewater Step 2.2.1, use the toxicity evaluation index calculated in step 2.1.2 as the ordinate y, substitute it into the curve fitted in step 1.3.3, and calculate the corresponding abscissa x, that is, the biological toxicity of the industrial wastewater after treatment is equivalent to the dilution multiple before treatment; Step 2.2.2, based on the results of step 2.2.1, calculate the reduction rate of biological toxicity of industrial wastewater before and after treatment. The reduction rate is characterized by the dilution multiple of industrial wastewater before treatment. The formula is as follows: Where x is the dilution multiple of the biological toxicity of industrial wastewater after treatment compared to that before treatment.

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