A method for reducing the risk of composite pollutants in sewage

Abstract

The present invention discloses a method for reducing the risk of composite pollutants in sewage, belonging to the technical field of sewage treatment. The method comprises the following steps: S1 measuring the concentration of dissolved organic carbon and the total concentration of composite pollutants in the sewage; S2 measuring the proportion P of the dissolved organic matter molecules with a modified aromaticity index ≥ 0.5 in the sewage; S3 selecting a corresponding filling scheme for the dual-media adsorption column based on the ratio of the concentration of dissolved organic carbon to the total concentration of composite pollutants and P. The method provided by the present invention can in-situ upgrade the existing activated carbon adsorption process, effectively reduce the risk of composite pollutants in sewage, and effectively ensure the safety of the effluent from the sewage treatment plant.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and specifically relates to a method for reducing the risk of composite pollutants in sewage. Background Art

[0002] Extensive research has shown that the combined risks of composite pollutants are often significantly higher than the safety level, even if the pollution risk of a single pollutant is lower than the safety level. Sewage treatment plants are one of the main media between these pollutants and environmental water bodies. However, it is worrying that traditional sewage treatment processes are difficult to effectively remove these composite pollutants. Due to their high polarity and high mobility, hydrophilic pollutants are more likely to "escape" in the sewage treatment system of sewage plants and thus enter the environmental water bodies. Some of these composite pollutants accumulate through the food chain as persistent organic pollutants and pose stronger health risks to organisms. Some can be degraded through physical, biological and other means, but often produce secondary products with stronger toxicity. Therefore, effectively removing such composite pollutants in sewage plants is of great significance for maintaining water environment safety.

[0003] The activated carbon treatment process is a commonly used tertiary treatment process in current sewage treatment plants. However, due to its main action mechanisms being hydrophobic interaction and electrostatic attraction, the treatment effect of activated carbon on hydrophilic composite pollutants is less than satisfactory. In addition, there are a large number of dissolved organic matter (DOM) molecules in actual sewage that are more likely to bind to the adsorption sites on the activated carbon, blocking the pores of the activated carbon, resulting in the activated carbon treatment process being difficult to play a role in the actual sewage treatment process for such hydrophilic composite pollutants. In recent years, more and more new adsorption materials have been developed and applied to actual sewage scenarios to remove hydrophilic composite pollutants. The Chinese invention patent with the application number of CN202010663210.4 discloses a method for synchronously removing antibiotic and heavy metal composite pollution in water. This invention synthesizes a silica template assisted by a triblock copolymer F127, then carbonizes glucose under acidic conditions, and then removes the silicon template under alkaline conditions to obtain a glucose mesoporous carbon material. The application in the effluent of the pig farm wastewater treatment process shows that the removal rate of this mesoporous carbon material for hydrophilic composite pollutants (tetracycline, ciprofloxacin, sulfadiazine) can reach more than 80%, and heavy metal ions can be synchronously removed. However, the preparation of the adsorbent used in this method requires strong acids, strong bases and high-temperature calcination, and the process is complex and difficult to be directly adapted to the existing sewage treatment process.

[0004] In summary, in the actual treatment process, there are many types of actual sewage and the components of the composite pollutants in each type of sewage are different. At the same time, due to the high polarity and high mobility of the composite pollutants themselves, the adsorption treatment methods such as activated carbon in the prior art have poor treatment effects on hydrophilic composite pollutants. And after the modification of activated carbon in the prior art, it is also impossible to have good applicability to the various composite pollutants that may exist in multiple types of actual sewage. Therefore, the existing adsorption technology does not conduct targeted design on the medium filling of the adsorption column, making it difficult to meet the requirements of efficient and practical treatment. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a method for reducing the risk of composite pollutants in sewage, which can efficiently remove hydrophilic composite pollutants in various sewage environments.

[0006] A method for reducing the risk of composite pollutants in sewage includes the following steps:

[0007] S1: Measure the dissolved organic carbon concentration C DOC and the total concentration C HCP of the composite pollutants in the sewage;

[0008] S2: Calculate the ratio P of the number of molecules of dissolved organic matter molecules with a modified aromaticity index AI mod ≥ 0.5 in the sewage to the total number of molecules of dissolved organic matter molecules in the sewage;

[0009] S3: Based on the ratio of the dissolved organic carbon concentration C DOC to the total concentration C HCP of the composite pollutants, and the P, determine the filling ratio of the two media in the dual-media adsorption column, and then use the dual-media adsorption column to perform risk reduction treatment on the sewage.

[0010] Note: Through the above method, it is possible to determine a suitable adsorption column for adsorbing sewage according to the specific composite pollution indicators in the sewage, with strong pertinence. The ratio P can express the content of aromatic rings in organic compounds, and the ratio P reflects the behavior, source, and potential ecological impact of molecules in the environment. In summary, by adjusting the filling ratio of the dual media through the above method, it is possible to reduce the risk of composite pollutants in actual sewage with different pollution characteristics, which is convenient for in-situ upgrading and transformation on the existing activated carbon adsorption devices in actual sewage treatment plants, and has wide applicability and good effects.

[0011] Further, the sewage is the secondary effluent of a sewage treatment plant and the effluent from the subsequent process section of the secondary effluent.

[0012] Note: The above effluent can avoid the influence of pollutants in the water before the secondary effluent on the adsorption column, such as blockage and damage.

[0013] Further, in the step S1, the composite pollutant is an organic compound with a logarithm of octanol / water partition coefficient logK ow ≤2.5 in the sewage.

[0014] Note: The octanol / water partition coefficient (Octanol-Water Partition Coefficient, abbreviated as K ow ) is a parameter that measures the partitioning ability of an organic compound between octanol and water, and it reflects the hydrophobicity or lipophilicity of the compound. The higher the value of K ow , the easier it is for the compound to partition into octanol, that is, the more hydrophobic it is; conversely, the lower the value of K ow , the more hydrophilic the compound is. The present invention is directed to hydrophilic composite pollutants, and according to the above screening method, it can treat more hydrophilic organic compounds in water bodies to reduce the pollution risk.

[0015] Further, in the S2, the calculation method of the modified aromaticity index AI mod is as follows:

[0016] For each dissolved organic matter molecule in the sewage, first determine the number of atoms of each element in the dissolved organic matter molecule, and then substitute the number of atoms of each element into the following formula (1) to calculate the modified aromaticity index;

[0017] ;

[0018] In formula (1), is the modified aromaticity index, is the number of carbon atoms, is the number of hydrogen atoms, is the number of oxygen atoms, is the number of nitrogen atoms, is the number of sulfur atoms, is the number of phosphorus atoms;

[0019] The calculation method of the ratio P is as formula (2):

[0020] ;

[0021] In formula (2), is the number of dissolved organic matter molecules with a modified aromaticity index ≥0.5 in the sewage water sample, is the total number of dissolved organic matter molecules in the sewage water sample.

[0022] Description: Through the above calculation formula, the content of aromatic rings in organic compounds can be expressed based on the number of dissolved organic matter molecules, which can help identify and distinguish different types of organic compounds. The above settings can study and analyze the behavior, sources, and potential ecological impacts of dissolved organic matter molecules in the environment.

[0023] Further, the two media in the dual-media adsorption column are activated carbon and restricted water-modified activated carbon respectively, and the dual-media adsorption column is filled with activated carbon and restricted water-modified activated carbon in sequence from bottom to top.

[0024] Description: The above dual media can be applied to various actual sewage treatment processes and have good treatment effects.

[0025] Further, the preparation method of the restricted water-modified activated carbon is as follows:

[0026] First, the activated carbon is crushed, screened, and washed, and then dried at 110 °C for 11 - 24 h to obtain dried activated carbon; subsequently, the dried activated carbon is taken out and placed in a constant temperature and humidity box at a temperature of 22 - 27 °C and a humidity of 95% - 200% for 40 - 72 h for modification; after the modification is completed, it is taken out and placed in a constant temperature oven at 25 - 40 °C and left to stand for 15 - 45 min to obtain restricted water-modified activated carbon.

[0027] Description: Through the above method, the adsorption performance of activated carbon can be improved and its pore structure can be optimized. Under high humidity conditions, water molecules may enter the micropores of activated carbon, resulting in pore expansion, increasing the pore volume and specific surface area; humidity treatment may promote the formation of surface functional groups on activated carbon, such as hydroxyl groups and carboxyl groups, which can enhance the chemical adsorption ability of activated carbon for specific pollutants; under high humidity conditions, restricted water may form inside the pores of activated carbon, and the presence of this water may change the microenvironment inside the pores and provide more adsorption sites, affecting adsorption kinetics and selectivity; the presence of restricted water may lead to an ordered arrangement of water molecules inside the pores, and this orderliness can improve the adsorption of composite pollutants.

[0028] Further, determining the filling ratio of the two media in the dual-media adsorption column for adsorbing sewage based on the ratio of the dissolved organic carbon concentration to the total concentration of composite pollutants and the P includes:

[0029] When C in the sewage DOC / C HCP ≤ 1000 and P ≤ 20%, the filling ratio of activated carbon to restricted water-modified activated carbon is 1:1;

[0030] When C in the sewage DOC / C HCPWhen ≤1000 and P > 20%, the filling ratio of activated carbon to restricted water modified activated carbon is 2:1;

[0031] When the C in the sewage DOC / C HCP > 1000, the filling ratio of activated carbon to restricted water modified activated carbon is 4:1.

[0032] Note: Through the above settings, the ratio of the treatment medium can be set based on the ratio of the dissolved organic carbon concentration to the total concentration of composite pollutants in the sewage and P, making it more suitable for the treatment process of composite pollutants in the sewage.

[0033] Further, after the crushing and screening, the particle size of the activated carbon obtained is 0.3 - 0.5 mm. Preferably, the water quality of the sewage entering the dual - medium adsorption column satisfies C DOC < 20 mg / L and the turbidity < 10 NTU.

[0034] Note: Through the above particle size setting, it can be applicable to the treatment process of the present invention; the above limitation on the sewage water quality can make the damage of the sewage to the dual - medium adsorption column smaller, and for the water quality within the above range, the dual - medium adsorption column has a better treatment effect on the composite pollutants in the sewage.

[0035] Further, in S3, the method for reducing the risk of sewage by using the dual - medium adsorption column is: introducing the sewage into the adsorption column and standing for 30 - 60 min, and the risk reduction treatment is completed.

[0036] Note: The above static adsorption treatment can effectively adsorb the composite pollutants in the sewage and reduce the potential risks in the sewage.

[0037] Further, when the sewage belongs to secondary effluent, the time for introducing the sewage into the adsorption column and standing is 45 - 60 min; when the sewage belongs to the effluent of the subsequent process section of secondary effluent, the time for introducing the sewage into the adsorption column and standing is 30 - 44 min; among them, the subsequent process section of secondary effluent includes but is not limited to coagulation sedimentation tank, fabric filter, denitrification filter, ultraviolet / ozone disinfection tank, etc.

[0038] Note: Through the above - mentioned differentiated setting of time for different effluents, while ensuring the treatment effect on the sewage, the standing time can be reduced and the cost can be saved.

[0039] Further, in the above technical solution, the risk of composite pollutants is calculated in terms of total toxicity unit (TU sum ), and the calculation formula is as follows:

[0040] ;

[0041] Among them, TU sum represents the total toxicity unit of the sewage, and TU i represents the toxicity unit of the i th pollutant; MEC i represents the detected concentration of the i th pollutant in the sewage; EC 50,i represents the half-effect concentration of the i th pollutant.

[0042] It should be noted that through the above calculation method, the total toxicity risk is obtained. The total toxicity risk is an index used to evaluate the risk of complex pollutants in water bodies and can measure the risk of complex pollutants in the sewage. That is, through the above total toxicity unit, it can be used to quantitatively evaluate the treatment effects before and after of the present invention.

[0043] The beneficial effects of the present invention are as follows: The present invention can determine a suitable adsorption column for treatment aiming at the complex pollution situation in the sewage, which can improve the pertinence in the sewage treatment process. The content of aromatic rings in organic compounds can be expressed by the ratio P, reflecting and analyzing the behavior, source and potential ecological impact of molecules in the environment. At the same time, by adjusting the filling ratio of the dual media through the above method, the risk reduction of complex pollutants in actual sewage with different pollution characteristics can be achieved, which is convenient for in-situ upgrading and transformation on the existing activated carbon adsorption device in actual sewage plants, having wide applicability and good effects. Meanwhile, the present invention uses modified activated carbon to reduce the risk of complex pollutants in actual sewage, having the advantages of low price, green and low-carbon, etc. Description of the Drawings

[0044] Figure 1 is the method schematic diagram of Embodiment 1 of the present invention;

[0045] Figure 2 is the AI mod distribution and proportion of each part of DOM molecules in the secondary effluent sample in Embodiment 1 of the present invention;

[0046] Figure 3 is the AI mod distribution and proportion of each part of DOM molecules in the secondary effluent sample in Embodiment 2 of the present invention;

[0047] Figure 4 is the AI mod distribution and proportion of each part of DOM molecules in the secondary effluent sample in Embodiment 3 of the present invention. Detailed Embodiments

[0048] To further elaborate on the methods adopted and the effects achieved by the present invention, the technical solutions of the present invention will be clearly and completely described below in combination with experiments.

[0049] Example 1: As Figure 1 shown, a method for reducing the risk of composite pollutants in sewage includes the following steps:

[0050] S1: Measure the concentration of dissolved organic carbon C DOC and the total concentration of composite pollutants C HCP ;

[0051] The sewage is the secondary effluent of a sewage treatment plant and the effluent of the subsequent process section of the secondary effluent; the composite pollutants are organic substances with a logarithm of the octanol / water partition coefficient logK ow ≤ 2.5;

[0052] S2: Calculate the ratio P of the number of molecules of dissolved organic matter with a modified aromaticity index AI mod ≥ 0.5 to the total number of molecules of dissolved organic matter in the sewage;

[0053] In S2, the calculation method of the modified aromaticity index AI mod is as follows:

[0054] For each molecule of dissolved organic matter in the sewage, first determine the number of atoms of each element in the molecule of dissolved organic matter, and then substitute the number of atoms of each element into the following formula (1) to calculate the modified aromaticity index;

[0055] ;

[0056] In formula (1), is the modified aromaticity index, is the number of carbon atoms, is the number of hydrogen atoms, is the number of oxygen atoms, is the number of nitrogen atoms, is the number of sulfur atoms, is the number of phosphorus atoms;

[0057] The calculation method of the ratio P is as formula (2):

[0058] ;

[0059] In formula (2), is the number of molecules of dissolved organic matter with a modified aromaticity index ≥ 0.5 in the sewage water sample, is the total number of molecules of dissolved organic matter in the sewage water sample;

[0060] S3: Based on the concentration of dissolved organic carbon C DOC and the total concentration of composite pollutants C HCPDetermine the filling ratio of the two media in the dual-media adsorption column based on the ratio and the P, and then use the dual-media adsorption column to perform risk reduction treatment on the sewage;

[0061] Among them, the two media in the dual-media adsorption column are activated carbon and restricted water-modified activated carbon respectively, and the activated carbon and the restricted water-modified activated carbon are filled in the dual-media adsorption column from bottom to top in sequence; among them, the quality of the sewage entering the dual-media adsorption column satisfies C DOC < 20 mg / L, turbidity < 10 NTU;

[0062] The preparation method of the restricted water-modified activated carbon is as follows:

[0063] First, crush, screen, and wash the activated carbon, and then dry it at 110 °C for 12 h to obtain dried activated carbon; subsequently, take out the dried activated carbon and place it in a constant temperature and humidity box at a temperature of 25 °C and a humidity of 98% for 48 h for modification; after the modification is completed, take it out and place it in a constant temperature oven at 30 °C and let it stand for 35 min to obtain the restricted water-modified activated carbon;

[0064] After the crushing and screening, the particle size of the activated carbon obtained is 0.3~0.5 mm;

[0065] In the embodiment of the present invention, determining the filling ratio of the two media in the dual-media adsorption column for adsorbing sewage based on the ratio of the dissolved organic carbon concentration to the total concentration of the composite pollutants and the P value includes:

[0066] When C in the sewage DOC / C HCP ≤ 1000 and P ≤ 20%, the filling ratio of the activated carbon to the restricted water-modified activated carbon is 1:1;

[0067] When C in the sewage DOC / C HCP ≤ 1000 and P > 20%, the filling ratio of the activated carbon to the restricted water-modified activated carbon is 2:1;

[0068] When C in the sewage DOC / C HCP > 1000, the filling ratio of the activated carbon to the restricted water-modified activated carbon is 4:1.

[0069] The method for using the dual-media adsorption column to perform risk reduction treatment on the sewage is: introducing the sewage into the adsorption column and letting it stand for 30~60 min, and the risk reduction treatment is completed;

[0070] Specifically, when the sewage is secondary effluent, the time for introducing the sewage into the adsorption column and letting it stand is 55 min;

[0071] In the above technical solution, the risk of composite pollutants is calculated in terms of the total toxicity unit (TU sum ), and the calculation formula is as follows:

[0072] ;

[0073] Among them, TU sum represents the total toxicity unit of the sewage, and TU i represents the toxicity unit of the i th pollutant; MEC i represents the detected concentration of the i th pollutant in the sewage; EC 50,i represents the median effect concentration of the i th pollutant; Through the above calculation method, the risk of the composite pollutants in the sewage can be measured, and through this total toxicity unit, it can be used as an index to quantitatively evaluate the treatment effect before and after of the present invention.

[0074] Exemplarily:

[0075] Adopt the method of Example 1, and illustrate the effect through an example of the actual process, specifically as follows: The sewage used comes from the secondary effluent of a municipal sewage treatment plant in the south. The basic water quality characteristics of this secondary effluent are: the average pH is 7.24, the average dissolved organic carbon is 21.07 mg / L, and the average turbidity is 5.73 NTU;

[0076] Adopt the method of Example 1 of the present invention to treat this simulated wastewater, and the implementation results obtained from the specific steps are as follows:

[0077] S1: Collect the sewage sample and measure its dissolved organic carbon concentration to be 13.21 mg / L, that is, C DOC = 13.21 mg / L; Measure the total concentration of composite pollutants to be 5600.9 ng / L, that is, C HCP = 5600.9 ng / L;

[0078] S2: Measure the ratio P of the number of molecules of dissolved organic matter (DOM) with a modified aromaticity index AI mod ≥ 0.5 in the sewage to the total number of molecules of dissolved organic matter in the sewage: A total of 7247 DOM molecules are identified, and use the formula (1); Calculate the AI mod of the above molecules, and the result is as Figure 2 shown; Calculate the proportion of the modified aromaticity index AI mod of DOM molecules in the water sample that is greater than or equal to 0.5, and obtain P = 18.91%;

[0079] S3: Based on the ratio of the dissolved organic carbon concentration to the total concentration of composite pollutants (CDOC / C HCP = 2359) and P (P = 18.91%). An adsorption column filled with activated carbon and restricted water-modified activated carbon in a ratio of 4:1 was selected. The specific operation steps are as follows:

[0080] (1) Crush, screen the activated carbon to 0.3 - 0.5 mm, wash it, and thoroughly dry it at 110°C for 12 h. Subsequently, take it out and place it in a constant temperature and humidity chamber at 25°C and 98% humidity for 48 h. After the modification is completed, take it out and place it in a 30°C constant temperature oven to balance for 35 min;

[0081] (2) Fill the double-medium adsorption column with activated carbon and restricted water-modified activated carbon from bottom to top in sequence, and the filling ratio is activated carbon:restricted water-modified activated carbon = 4:1;

[0082] (3) Since the C DOC = 13.21 mg / L < 20 mg / L and the turbidity = 5.73 NTU < 10 NTU of this sewage, it meets the water quality requirements for entering the double-medium adsorption column. The sewage enters the adsorption column from bottom to top through a peristaltic pump, and the treatment time is 55 min.

[0083] The average concentrations of composite pollutants and the effluent risks after treatment by four methods, namely raw water (control group 1), activated carbon adsorption column (control group 2), restricted water-modified activated carbon adsorption column (control group 3), and double-medium adsorption column (Example 1), are shown in Table 1 and Table 2 respectively.

[0084] Combining Table 1 and Table 2, after treatment with the activated carbon adsorption column (control group 2), the concentrations of various composite pollutants are reduced by 22 - 82%, and the overall effluent risk is 0.0647 T.U.; after treatment with the restricted water-modified activated carbon adsorption column (control group 2), the concentrations of composite pollutants are reduced by 33 - 86%, and the overall effluent risk is 0.0381 T.U. After upgrading and transforming with this method to select a double-medium adsorption column with activated carbon:restricted water-modified activated carbon = 4:1, the pollutant concentrations after treatment are reduced by 56 - 92%, and the overall effluent risk is 0.0214 T.U.

[0085] Therefore, after being transformed by this method, the treatment effect is significantly improved. After treatment with the double-medium adsorption column, the overall effluent risk can be significantly reduced. The effluent risks are reduced from 0.0647 T.U. (activated carbon adsorption column) and 0.0381 T.U. (restricted water-modified activated carbon adsorption column) to 0.0214 T.U. (double-medium adsorption column) respectively, reducing the effluent risks by 67% and 44% respectively, and significantly reducing the risk of composite pollutants in the sewage.

[0086] Table 1 Concentrations of composite pollutants in the effluent treated by the adsorption column in Example 1

[0087]

[0088] Table 2 Total risks of raw water and treated water from adsorption column in Example 1

[0089]

[0090] In summary, by comparing Control Group 1 with Example 1, it can be seen that the adsorption (removal) effect of the composite pollutants by the method of Example 1 of the present invention is better. Compared with Control Group 1, the removal rate can be increased by 2 to 3 times. The reason is that in Example 1, an adsorption column is used for treatment, indicating that the adsorption column in Example 1 can effectively remove the composite pollutants.

[0091] By comparing Control Group 2, Control Group 3 with Example 1, it can be seen that after the composite pollutants are removed by the method of Example 1 of the present invention, the removal rates of various pollutants have been significantly improved, indicating that compared with the direct use of activated carbon or the direct use of modified activated carbon, the adsorption effect of the adsorption column obtained by the dual-medium ratio in Example 1 of the present invention is better. The reason is that the method in Example 1 uses a dual-medium adsorbent to effectively remove the composite pollutants according to the characteristics of the composite pollutants, which is a treatment method not conceived in the prior art only by modifying activated carbon and cannot achieve the technical effect.

[0092] Example 2: The difference from Example 1 is that the sewage used in this example comes from the secondary effluent of a municipal sewage treatment plant along the coast. The basic water quality characteristics of the secondary effluent are: the average pH is 8.17, the average dissolved organic carbon is 8.21 mg / L, and the average turbidity is 6.28 NTU; by adding target pollutants, the average concentrations of various pollutants in the obtained sewage are shown in Table 3.

[0093] The method of the present invention is used to treat this simulated wastewater, and the specific steps are as follows:

[0094] S1: Collect the sewage sample and measure its dissolved organic carbon concentration to be 5.17 mg / L, i.e., C DOC = 5.17 mg / L; measure the total concentration of the composite pollutants to be 11998.17 ng / L, i.e., C HCP = 11998.17 ng / L;

[0095] S2: Measure the ratio P of the number of molecules of dissolved organic matter (DOM) with a modified aromaticity index (AI mod ) ≥ 0.5 in the sewage to the total number of molecules of dissolved organic matter in the sewage: A total of 11716 DOM molecules are identified, and the formula (1); is used to calculate the AI mod of the above molecules, and the result is as Figure 3As shown; calculate the modified aromaticity index AI of DOM molecules in the water sample mod The proportion of values greater than or equal to 0.5 is obtained as P = 15.53%;

[0096] S3: Based on the ratio of the dissolved organic carbon concentration to the total concentration of the composite pollutants (C DOC / C HCP = 431) and P (P = 15.53%), select an adsorption column filled with activated carbon and restricted water-modified activated carbon in a 1:1 ratio. The specific operation steps are as follows:

[0097] (1) Crush, sieve the activated carbon to 0.3 - 0.5 mm, wash it, and thoroughly dry it at 110°C for 20 h; then, take it out and place it in a constant temperature and humidity chamber at a temperature of 22.7°C and a humidity of 100% for 60 h; after the modification is completed, take it out and place it in a 40°C constant temperature oven to balance for 15 min;

[0098] (2) Fill the double-medium adsorption column with activated carbon and restricted water-modified activated carbon from bottom to top in sequence, and the filling ratio is activated carbon:restricted water-modified activated carbon = 1:1;

[0099] (3) Since the simulated C DOC = 5.17 mg / L < 20 mg / L, and the turbidity = 6.28 NTU < 10 NTU, which meets the water quality requirements for entering the double-medium adsorption column; the sewage enters the adsorption column from bottom to top through a peristaltic pump, and the treatment time is set to 45 min.

[0100] The average concentrations of the composite pollutants and the effluent risks after treatment of the raw water, activated carbon adsorption column, restricted water-modified activated carbon adsorption column, and double-medium adsorption column are shown in Tables 3 and 4. After treatment with the activated carbon adsorption column (control group 5), the concentration of the composite pollutants is reduced by 27 - 77%, and the overall effluent risk is 0.0665 T.U.; after treatment with the restricted water-modified activated carbon adsorption column (control group 6), the concentration of the composite pollutants is reduced by 54 - 82%, and the overall effluent risk is 0.0422 T.U. After upgrading and transformation with this method, a double-medium adsorption column with a ratio of activated carbon:restricted water-modified activated carbon = 1:1 is selected. After treatment, the concentration of the composite pollutants is reduced by 71 - 92%, and the overall effluent risk is 0.0199 T.U. Therefore, after the transformation with this method, the treatment effect is significantly improved. The double-medium adsorption column can significantly reduce the overall effluent risk after treatment. The effluent risks are reduced from 0.0665 T.U. (activated carbon adsorption column) and 0.0422 T.U. (restricted water-modified activated carbon adsorption column) to 0.0121 T.U. (double-medium adsorption column), reducing the effluent risks by 70% and 55% respectively, effectively reducing the risk of composite pollutants in the sewage and ensuring the effluent safety.

[0101] Table 3 Concentrations of Composite Pollutants in the Effluent Treated by the Adsorption Column in Example 2

[0102]

[0103] Table 4 Total Risks of the Raw Water and the Effluent Treated by the Adsorption Column in Example 2

[0104]

[0105] In summary, by comparing Control Group 4 with Example 2, it can be seen that the adsorption (removal) effect of the composite pollutants by using the method of Example 2 of the present invention is better. Compared with Control Group 4, the removal rate can be increased by 2 to 3 times. The reason is that in Example 2, an adsorption column is used for treatment, indicating that the adsorption column in Example 2 can effectively remove the composite pollutants.

[0106] By comparing Control Group 5, Control Group 6 with Example 2, it can be seen that after the composite pollutants are removed by using Example 2 of the present invention, the removal rates of various pollutants have been significantly improved, indicating that compared with the direct use of activated carbon or the direct use of modified activated carbon, the adsorption effect of the adsorption column obtained by the dual-media ratio in Example 2 of the present invention is better. The reason is that the method in Example 2 uses a dual-media adsorbent, which can effectively remove the composite pollutants according to the characteristics of the composite pollutants. This is a treatment method not envisioned in the prior art where only activated carbon is modified and cannot achieve the technical effect.

[0107] Example 3: The difference from Example 1 is that the sewage used in this example comes from the secondary effluent of a municipal sewage treatment plant inland. The basic water quality characteristics of the secondary effluent are as follows: the average pH is 7.67, the average dissolved organic carbon is 8.70 mg / L, and the average turbidity is 7.45 NTU. The specific steps are as follows:

[0108] S1: Collect the sewage sample and measure its dissolved organic carbon concentration to be 7.33 mg / L, i.e., C DOC = 7.33 mg / L; measure the total concentration of the composite pollutants to be 7830.78 ng / L, i.e., C HCP = 7830.78 ng / L;

[0109] S2: Measure the ratio P of the number of molecules of dissolved organic matter (DOM) with a modified aromaticity index (AI mod ) ≥ 0.5 in the sewage to the total number of molecules of dissolved organic matter in the sewage: A total of 8849 DOM molecules are identified, and using the formula (1); calculate the AI mod of the above molecules, and the result is as Figure 4 shown; calculate the modified aromaticity index AI of the DOM molecules in the water samplemod The proportion with a value greater than or equal to 0.5 is obtained, and P = 21.62%;

[0110] S3: Based on the ratio of the dissolved organic carbon concentration to the total concentration of the composite pollutants (C DOC / CHCP = 936) and P (P = 21.62%), select an adsorption column filled with activated carbon and restricted water-modified activated carbon in a ratio of 2:1. The specific operation steps are as follows:

[0111] (1) Crush, screen the activated carbon to 0.3 - 0.5 mm, wash it, and thoroughly dry it at 110 °C for 24 h; then, take it out and place it in a constant temperature and humidity chamber at a temperature of 22.3 °C and a humidity of 95% for 72 h; after the modification is completed, take it out and place it in a 30 °C constant temperature oven to balance for 20 min;

[0112] (2) Fill the double-medium adsorption column with activated carbon and restricted water-modified activated carbon from bottom to top in sequence, and the filling ratio is activated carbon:restricted water-modified activated carbon = 2:1;

[0113] (3) Since the C DOC of this sewage = 7.33 mg / L < 20 mg / L, and the turbidity = 7.45 NTU < 10 NTU, it meets the water quality requirements for entering the double-medium adsorption column; the sewage enters the adsorption column from bottom to top through a peristaltic pump, and the treatment time is 60 min.

[0114] The average concentrations of the composite pollutants and the effluent risks after treatment of the raw water, activated carbon adsorption column, restricted water-modified activated carbon adsorption column, and double-medium adsorption column are shown in Tables 5 and 6 respectively. After treatment with the activated carbon adsorption column (control group 8), the concentration of the composite pollutants is reduced by 16 - 45%, and the overall effluent risk is 0.0428 T.U.; after treatment with the restricted water-modified activated carbon adsorption column (control group 9), the concentration of the composite pollutants is reduced by 21 - 54%, and the overall effluent risk is 0.0333 T.U. After upgrading and transforming with this method and selecting a double-medium adsorption column with activated carbon:restricted water-modified activated carbon = 2:1, the pollutant concentration is reduced by 32 - 72% after treatment, and the overall effluent risk is 0.0176 T.U. Therefore, after the transformation with this method, the treatment effect is significantly improved. After treatment with the double-medium adsorption column, the overall effluent risk can be significantly reduced. The effluent risks are reduced from 0.0428 T.U. (activated carbon adsorption column) and 0.0333 T.U. (restricted water-modified activated carbon adsorption column) to 0.0176 T.U. (double-medium adsorption column) respectively, reducing the effluent risks by 58% and 47% respectively, and significantly reducing the risk of the composite pollutants in the sewage.

[0115] Table 5 Concentrations of composite pollutants in the effluent treated by the adsorption column in Example 3

[0116]

[0117] Table 6 Total risks of raw water and treated effluent from the adsorption column in Example 3

[0118]

[0119] In summary, by comparing Control Group 7 with Example 3, it can be seen that the adsorption (removal) effect of Example 3 of the method of the present invention on composite pollutants is better, and the removal rate is increased more compared with Control Group 7. The reason is that in Example 3, an adsorption column is used for treatment, indicating that the adsorption column in Example 3 can effectively remove composite pollutants.

[0120] By comparing Control Group 8, Control Group 9 with Example 3, it can be seen that after removing composite pollutants using Example 3 of the present invention, the removal rates of various pollutants have been significantly improved, indicating that compared with the direct use of activated carbon or the direct use of modified activated carbon, the adsorption effect of the adsorption column obtained by the dual-media ratio in Example 3 of the present invention is better. The reason is that the method in Example 3 uses a dual-media adsorbent that can effectively remove composite pollutants according to the characteristics of the composite pollutants, which is a treatment method not envisioned in the prior art that only modifies activated carbon and cannot achieve the technical effect.

[0121] Example 4: The difference from Example 1 is that the preparation method of the restricted water-modified activated carbon is as follows: First, the activated carbon is crushed, screened, and washed, and then dried at 110 °C for 11 h to obtain dried activated carbon; subsequently, the dried activated carbon is taken out and placed in a constant temperature and humidity chamber at a temperature of 22 °C and a humidity of 95% for 72 h for modification; after the modification is completed, it is taken out and placed in a 40 °C constant temperature oven and left standing for 15 min to obtain the restricted water-modified activated carbon.

[0122] Example 5: The difference from Example 1 is that the preparation method of the restricted water-modified activated carbon is as follows: First, the activated carbon is crushed, screened, and washed, and then dried at 110 °C for 24 h to obtain dried activated carbon; subsequently, the dried activated carbon is taken out and placed in a constant temperature and humidity chamber at a temperature of 27 °C and a humidity of 200% for 40 h for modification; after the modification is completed, it is taken out and placed in a 25 °C constant temperature oven and left standing for 45 min to obtain the restricted water-modified activated carbon.

[0123] Example 6: The sewage belongs to the effluent from the subsequent process section (coagulation sedimentation tank) of secondary effluent. The sewage is introduced into the adsorption column and left standing for 30 min.

[0124] Example 7: The sewage belongs to the effluent from the subsequent process section (fabric filter) of secondary effluent. The sewage is introduced into the adsorption column and left standing for 44 min.

[0125] Example 8: The sewage is the effluent from the subsequent process section (denitrification filter) of the secondary effluent. The sewage is introduced into the adsorption column and left standing for 35 minutes.

[0126] Example 9: The sewage is the effluent from the subsequent process section (UV / ozone disinfection tank) of the secondary effluent. The sewage is introduced into the adsorption column and left standing for 40 minutes.

Claims

1. A method for reducing the risk of complex pollutants in sewage, characterized in that: The following steps are involved: S1: Determination of dissolved organic carbon concentration C in sewage DOC and the total concentration of composite pollutants C HCP ; S2: Calculation of the modified aromaticity index AI in wastewater mod The ratio P of the number of dissolved organic matter molecules ≥ 0.5 to the total number of dissolved organic matter molecules in the sewage; S3: Based on dissolved organic carbon concentration C DOC The total concentration of the combined pollutants C HCP The ratio of and P is used to determine the filling ratio of the two media in the dual-media adsorption column, and then the dual-media adsorption column is used to perform risk reduction treatment on the sewage; The method of determining the filling ratio of two media in a dual-medium adsorption column for adsorbing sewage based on the ratio of dissolved organic carbon concentration to total concentration of composite pollutants and P includes: When C DOC / C HCP When ≤1000 and P≤20%, the filling ratio of activated carbon to limited water modified activated carbon is 1:1; When C DOC / C HCP When ≤1000 and P>20%, the filling ratio of activated carbon to limited water-modified activated carbon is 2:1; When C DOC / C HCP When >1000, the filling ratio of activated carbon to limited water modified activated carbon is 4:

1.

2. A method for reducing the risk of complex pollutants in sewage according to claim 1, characterized in that: The sewage is the secondary effluent of the sewage treatment plant and the effluent from the subsequent process section of the secondary effluent.

3. A method for reducing the risk of complex pollutants in sewage as claimed in claim 1, characterized in that: The composite pollutant in step S1 is the logarithm of the octanol / water partition coefficient in the sewage. ow ≤ 2.5 organic matter.

4. A method for reducing the risk of complex pollutants in sewage as claimed in claim 1, characterized in that: Modified aromaticity index AI in S2 mod The calculation method is: For each dissolved organic matter molecule in the sewage, the number of atoms of each element in the dissolved organic matter molecule is first determined, and then the number of atoms of each element is substituted into the following formula (1) to calculate the modified aromaticity index; In formula (1), To correct the aromaticity index, is the number of atoms of carbon, is the number of atoms of hydrogen, is the number of atoms of oxygen, is the number of nitrogen atoms, is the number of sulfur atoms, is the number of atoms of phosphorus; The ratio P is calculated as shown in formula (2): In formula (2), is the number of dissolved organic matter molecules with a corrected aromaticity index ≥ 0.5 in the sewage sample, It is the total number of dissolved organic matter molecules in the sewage sample.

5. A method for reducing the risk of complex pollutants in sewage as claimed in claim 1, characterized in that: The two media in the dual-medium adsorption column are activated carbon and restricted water-modified activated carbon, respectively, and the dual-medium adsorption column is filled with activated carbon and restricted water-modified activated carbon in sequence from bottom to top; Wherein, the preparation method of the limited water modified activated carbon is: First, the activated carbon is crushed, sieved, and washed, and then dried at 110°C for 11-24 hours to obtain dried activated carbon; then, the dried activated carbon is taken out and placed in a constant temperature and humidity chamber at a temperature of 22-27°C and a humidity of 95-200% for 40-72 hours for modification; after the modification is completed, it is taken out and placed in a constant temperature oven at 25-40°C for 15-45 minutes to obtain limited water modified activated carbon.

6. A method for reducing the risk of complex pollutants in sewage as claimed in claim 5, characterized in that: After the crushing and screening, the activated carbon particles obtained have a diameter of 0.3-0.5 mm.

7. A method for reducing the risk of complex pollutants in sewage as claimed in claim 5, characterized in that: The method for risk reduction treatment of sewage using the dual-medium adsorption column described in S3 is: introducing the sewage into the adsorption column and letting it stand for 30 to 60 minutes, and the risk reduction treatment is completed.

8. A method for reducing the risk of complex pollutants in sewage as claimed in claim 7, characterized in that: When the sewage belongs to secondary effluent, the sewage is introduced into the adsorption column and allowed to stand for 45 to 60 minutes; when the sewage belongs to the effluent of the subsequent process section of secondary effluent, the sewage is introduced into the adsorption column and allowed to stand for 30 to 44 minutes; wherein, the subsequent process section of secondary effluent includes a coagulation sedimentation tank, a filter cloth filter tank, a denitrification filter tank and a UV / ozone disinfection tank.

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