Method for reducing risk of composite pollutants in sewage

Abstract

The invention discloses a method for reducing the risk of composite pollutants in sewage, and belongs to the technical field of sewage treatment. The method comprises the following steps: S1, measuring the concentration of soluble organic carbon and the total concentration of composite pollutants in sewage; s2, determining the proportion P of dissolved organic matter molecules with the modified aromaticity index greater than or equal to 0.5 in the sewage; and S3, selecting a corresponding double-medium adsorption column filling scheme based on the ratio of the concentration of the soluble organic carbon to the total concentration of the composite pollutants and the P. According to the method provided by the invention, the existing activated carbon adsorption process can be upgraded in situ, the risk of composite pollutants in sewage is effectively reduced, and the effluent safety of a sewage plant is effectively guaranteed.

Description

Technical Field

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

[0002] Extensive studies have shown that the combined risk of complex pollutants is often significantly higher than the safe level, even if the pollution risk of a single pollutant is lower than the safe level. Wastewater treatment plants are one of the main media between these pollutants and environmental water bodies, but what is worrying is that traditional sewage treatment processes are difficult to effectively remove these complex pollutants. Hydrophilic pollutants are often more likely to "escape" in sewage treatment systems due to their high polarity and high mobility, and thus enter environmental water bodies. Some of these complex pollutants accumulate through the food chain as persistent organic pollutants and pose a greater health risk to organisms. Although some can be degraded by physical, biological and other means, they often produce more toxic secondary products. Therefore, the effective removal of such complex pollutants in sewage treatment plants is of great significance to maintaining the safety of the water environment.

[0003] Activated carbon treatment process is a commonly used tertiary treatment process in sewage treatment plants. However, due to its mechanism of action mainly being hydrophobic interaction and electrostatic attraction, the treatment effect of activated carbon on hydrophilic composite pollutants is unsatisfactory. 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 activated carbon, blocking the pores of activated carbon, making it difficult for activated carbon treatment process to play a role in the actual sewage treatment process for such hydrophilic composite pollutants. In recent years, more and more new adsorbent materials have been developed and applied to remove hydrophilic composite pollutants in actual sewage scenarios. The Chinese invention patent with invention patent application number CN202010663210.4 discloses a method for simultaneously removing antibiotic and heavy metal composite pollution in water. The invention uses triblock copolymer F127 to assist in the synthesis of silica templates, followed by carbonization of glucose under acidic conditions, and then removal of the silica template under alkaline conditions to obtain glucose mesoporous carbon materials. The application of the mesoporous carbon material in the effluent of the pig wastewater treatment process shows that the removal effect of the mesoporous carbon material on hydrophilic composite pollutants (tetracycline, ciprofloxacin, sulfadiazine) can reach more than 80%, and heavy metal ions can be removed simultaneously. However, the preparation of the adsorbent used in this method requires strong acid, strong base and high temperature calcination, the process is complicated and difficult to directly adapt to the existing sewage treatment process.

[0004] In summary, in the actual treatment process, there are many types of actual sewage and the composition of complex pollutants in each type of sewage is different. At the same time, due to the high polarity and high mobility of the complex pollutants themselves, the adsorption treatment methods such as activated carbon in the existing technology have poor treatment effects on hydrophilic complex pollutants. Moreover, after the modified activated carbon in the existing technology, it is also unable to have good applicability for the various complex pollutants that may exist in various types of actual sewage. Therefore, the existing adsorption technology does not carry out targeted design of 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 complex pollutants in sewage, which can achieve efficient removal of hydrophilic complex pollutants in various sewage environments.

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

[0007] Description: Through the above method, it is possible to determine the appropriate adsorption column for adsorption treatment of sewage according to the specific complex pollution indicators in the sewage. It is highly targeted and the ratio P can be used to express the content of aromatic rings in organic compounds. The ratio P reflects and analyzes the behavior, source and potential ecological impact of molecules in the environment. In summary, by adjusting the filling ratio of the dual medium 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 of the existing activated carbon adsorption device in the actual sewage treatment plant, and has wide applicability and good effect.

[0008] Furthermore, the sewage is secondary effluent from a sewage treatment plant and effluent from a subsequent process section of the secondary effluent.

[0009] Note: The above-mentioned effluent can prevent pollutants in the water body before the secondary effluent from clogging or damaging the adsorption column.

[0010] Furthermore, the composite pollutant in step S1 is the logarithm of the octanol / water partition coefficient in the sewage. ow ≤2.5 organic matter.

[0011] Description: Octanol / water partition coefficient (Octanol-Water Partition Coefficient, referred to as K ow ) is a parameter that measures the partitioning ability of organic compounds between octanol and water, which reflects the hydrophobicity or lipophilicity of the compound. ow The higher the value of K, the easier it is for the compound to be distributed into octanol, that is, the more hydrophobic it is; conversely, ow The lower the value, the more hydrophilic the compound is. The present invention targets hydrophilic composite pollutants and can treat more hydrophilic organic matter in the water body according to the above screening method to reduce the risk of pollution.

[0012] Furthermore, the 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.

[0013] Note: Through the above calculation formula, the content of aromatic rings in organic compounds can be expressed according to the number of dissolved organic matter molecules, which can help identify and distinguish different types of organic matter. The above settings can study and analyze the behavior, source and potential ecological impact of dissolved organic matter molecules in the environment.

[0014] Furthermore, the two media in the dual-media adsorption column are activated carbon and restricted water-modified activated carbon, and the dual-media adsorption column is filled with activated carbon and restricted water-modified activated carbon in sequence from bottom to top.

[0015] Note: The above dual media can be applied to a variety of actual sewage treatment processes and has good treatment effects.

[0016] Furthermore, 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.

[0017] Note: The above method can improve the adsorption performance of activated carbon and optimize its pore structure. Under high humidity conditions, water molecules may enter the micropores of activated carbon, causing pore expansion and increasing pore volume and specific surface area. Humidity treatment may promote the formation of functional groups on the surface of activated carbon, such as hydroxyl and carboxyl groups. These functional groups can enhance the chemical adsorption capacity of activated carbon for specific pollutants. Under high humidity conditions, confined water may form in the pores of activated carbon. The presence of this water may change the microenvironment in the pores and provide more adsorption sites, affecting the adsorption kinetics and selectivity. The presence of confined water may lead to the orderly arrangement of water molecules in the pores. This orderliness can improve the adsorption of complex pollutants.

[0018] Further, the filling ratio of two media in the dual-medium adsorption column for adsorbing sewage based on the ratio of dissolved organic carbon concentration to total concentration of complex 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.

[0019] Note: Through the above settings, the proportion of the treatment medium can be set based on the ratio of the dissolved organic carbon concentration in the sewage to the total concentration of the composite pollutants and P, making it more suitable for the treatment process of composite pollutants in sewage.

[0020] Furthermore, after the crushing and screening, the activated carbon particle size is 0.3-0.5 mm. Preferably, the sewage quality entering the dual-medium adsorption column meets C DOC <20 mg / L, turbidity<10 NTU.

[0021] Note: The above-mentioned particle size setting can be applied to the treatment process of the present invention; the above-mentioned limitation on sewage water quality can reduce the damage of sewage to the dual-medium adsorption column, and for water quality within the above-mentioned range, the dual-medium adsorption column has a better treatment effect on complex pollutants in sewage.

[0022] Furthermore, the method for using the dual-medium adsorption column to perform risk reduction treatment on sewage 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.

[0023] Note: The above-mentioned static adsorption treatment can effectively adsorb complex pollutants in sewage and reduce potential risks in sewage.

[0024] Furthermore, 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 the 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 the secondary effluent includes but is not limited to a coagulation sedimentation tank, a filter cloth filter, a denitrification filter, an ultraviolet / ozone disinfection tank, etc.

[0025] Note: By setting the above-mentioned different water discharge times, it is possible to reduce the standing time and save costs while ensuring the sewage treatment effect.

[0026] Furthermore, in the above technical solution, the risk of composite pollutants is expressed in terms of total toxicity units (TU sum ), the calculation formula is as follows: ; Among them, TU sum Indicates the total toxicity unit of sewage, TU i Indicates i Toxicity unit of a pollutant; MEC i Indicates the sewage i The detection concentration of each pollutant; EC 50,i Indicates i The median effective concentration of a pollutant.

[0027] It is explained that the total toxicity risk is obtained through the above-mentioned calculation method. The total toxicity risk is an indicator used to evaluate the risk of complex pollutants in water bodies, and can measure the risk of complex pollutants in the sewage. That is, the above-mentioned total toxicity unit can be used as a quantitative evaluation of the effects before and after the treatment of the present invention.

[0028] The beneficial effects of the present invention are as follows: the present invention can determine the appropriate adsorption column for treatment according to the complex pollution in sewage, can improve the pertinence in the sewage treatment process, can express the content of aromatic rings in organic compounds through the ratio P, and reflect and analyze the behavior, source and potential ecological impact of molecules in the environment; at the same time, by adjusting the filling ratio of the dual medium through the above method, it is possible to reduce the risk of complex pollutants in actual sewage with different pollution characteristics, and facilitate in-situ upgrading and transformation on the existing activated carbon adsorption device of the actual sewage plant, which has wide applicability and good effect. At the same time, the present invention uses modified activated carbon to reduce the risk of complex pollutants in actual sewage, which has the advantages of low price, green and low carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the method of embodiment 1 of the present invention; Figure 2 is the AI ​​of DOM molecules in the secondary effluent sample in Example 1 of the present invention mod Distribution and proportion of each part; Figure 3 is the AI ​​of DOM molecules in the secondary effluent sample in Example 2 of the present invention mod Distribution and proportion of each part; Figure 4 is the AI ​​of DOM molecules in the secondary effluent sample in Example 3 of the present invention mod Distribution and proportion of each part. DETAILED DESCRIPTION

[0030] In order to further illustrate the method adopted by the present invention and the effect achieved, the technical solution of the present invention will be clearly and completely described in combination with experiments below.

[0031] Example 1: Figure 1 As shown, a method for reducing the risk of complex pollutants in sewage comprises the following steps: S1: Determination of dissolved organic carbon concentration C in sewage DOC and the total concentration of composite pollutants C HCP ; The sewage is the secondary effluent of the sewage treatment plant and the effluent of the subsequent process section of the secondary effluent; the composite pollutant is the logarithm of the octanol / water partition coefficient in the sewage, logK ow ≤ 2.5 organic matter; 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; 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, is the total number of dissolved organic matter molecules in the sewage sample; 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 two media in the dual-medium adsorption column are activated carbon and restricted water modified activated carbon, and the dual-medium adsorption column is filled with activated carbon and restricted water modified activated carbon from bottom to top; the sewage quality entering the dual-medium adsorption column meets C DOC <20 mg / L, turbidity <10 NTU; 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 12 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 25°C and a humidity of 98% for 48 hours for modification; after the modification is completed, it is taken out and placed in a constant temperature oven at 30°C for 35 minutes to obtain limited water modified activated carbon; After the crushing and screening, the activated carbon particle size is 0.3-0.5 mm; In the embodiment of the present invention, the filling ratio of two media in the dual-medium adsorption column for adsorbing sewage based on the ratio of dissolved organic carbon concentration to total concentration of composite pollutants and the P value 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.

[0032] The method of using the dual-medium adsorption column to perform risk reduction treatment on sewage is as follows: introducing the sewage into the adsorption column and letting it stand for 30 to 60 minutes, and the risk reduction treatment is completed; Specifically, when the sewage belongs to secondary effluent, the sewage is introduced into the adsorption column and allowed to stand for 55 minutes; In the above technical solution, the risk of composite pollutants is expressed in terms of total toxicity units (TU sum ), the calculation formula is as follows: ; Among them, TU sum Indicates the total toxicity unit of sewage, TU i Indicates i Toxicity unit of a pollutant; MEC i Indicates the sewage i The detection concentration of each pollutant; EC 50,i Indicates i The half-maximum effect concentration of each pollutant; through the above calculation method, the risk of complex pollutants in the sewage can be measured, and the total toxicity unit can be used as an indicator for quantitatively evaluating the effects before and after treatment of the present invention.

[0033] Exemplary: The method of Example 1 is used to illustrate the effect through an example of an actual process, as follows: the sewage used is secondary effluent from a municipal sewage treatment plant in the south, and the basic water quality characteristics of the secondary effluent are: an average pH value of 7.24, an average dissolved organic carbon value of 21.07 mg / L, and an average turbidity value of 5.73 NTU; The simulated wastewater was treated by the method of Example 1 of the present invention, and the implementation results obtained by the specific steps are as follows: S1: Collect the sewage sample and determine its dissolved organic carbon concentration, which is 13.21 mg / L, that is, C DOC =13.21mg / L; the total concentration of the composite pollutants was 5600.9 ng / L, i.e. C HCP =5600.9ng / L; S2: Determination of the modified aromaticity index AI in wastewater mod The ratio of the number of dissolved organic matter (DOM) molecules with a molecular mass of ≥ 0.5 to the total number of dissolved organic matter molecules in the sewage is P: A total of 7247 DOM molecules were identified, using the formula (1); Calculate the AI ​​of the above molecules mod , the results are as follows Figure 2 As shown; Calculate the modified aromaticity index AI of DOM molecules in water samples mod The proportion greater than or equal to 0.5 yields P = 18.91%; S3: Based on the ratio of dissolved organic carbon concentration to total concentration of complex pollutants (C DOC / C HCP =2359) and P (P=18.91%), select an adsorption column filled with activated carbon and activated carbon modified with limited water in a ratio of 4:1, and the specific operation steps are as follows: (1) The activated carbon was crushed, sieved to 0.3-0.5 mm, washed, and thoroughly dried at 110 °C for 12 h. Then, it was taken out and placed in a constant temperature and humidity chamber at 25 °C and 98% humidity for 48 h. After the modification was completed, it was taken out and placed in a constant temperature oven at 30 °C for 35 min. (2) The dual-medium adsorption column is filled with activated carbon and restricted water-modified activated carbon from bottom to top, with a filling ratio of activated carbon: restricted water-modified activated carbon = 4:1; (3) Since the sewage C DOC =13.21 mg / L<20 mg / L, and turbidity =5.73 NTU<10 NTU, which meets the water quality requirements for entering the dual-medium adsorption column; the sewage enters the adsorption column from bottom to top through the peristaltic pump, and the treatment time is 55 min.

[0034] The average concentrations of composite pollutants and effluent risks after treatment by the four methods of raw water (control group 1), activated carbon adsorption column (control group 2), restricted water modified activated carbon adsorption column (control group 3) and dual-media adsorption column (Example 1) are shown in Tables 1 and 2, respectively.

[0035] Combining Table 1 and Table 2, after treatment with the activated carbon adsorption column (control group 2), the concentration of multiple composite pollutants was reduced by 22~82%, and the overall effluent risk was 0.0647 TU; after treatment with the limited water modified activated carbon adsorption column (control group 2), the concentration of composite pollutants was reduced by 33~86%, and the overall effluent risk was 0.0381 TU. After upgrading this method, a dual-media adsorption column with activated carbon: limited water modified activated carbon = 4:1 was selected. After treatment, the pollutant concentration was reduced by 56~92%, and the overall effluent risk was 0.0214 TU.

[0036] Therefore, after the modification of this method, the treatment effect was significantly improved. After treatment with the dual-media adsorption column, the overall effluent risk can be significantly reduced. The effluent risk was reduced from 0.0647 TU (activated carbon adsorption column) and 0.0381 TU (limited water modified activated carbon adsorption column) to 0.0214 TU (dual-media adsorption column), respectively, reducing the effluent risk by 67% and 44%, respectively, significantly reducing the risk of complex pollutants in sewage.

[0037] Table 1 Concentration of composite pollutants in effluent treated by adsorption column in Example 1

[0038] Table 2 Total risk of raw water and effluent from adsorption column treatment in Example 1

[0039] In summary, by comparing the control group 1 with the embodiment 1, it can be seen that the adsorption (removal) effect of the composite pollutants by the method of the embodiment 1 of the present invention is better, and the removal rate can be increased by 2 to 3 times compared with the control group 1; the reason is that the adsorption column is used for treatment in the embodiment 1, which shows that the adsorption column of the embodiment 1 can effectively remove the composite pollutants; By comparing the control group 2 and the control group 3 with the example 1, it can be seen that after the composite pollutants are removed by the example 1 of the present invention, the removal rate of various pollutants is 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 the example 1 of the present invention is better. The reason is that the method in the example 1 adopts the dual-medium adsorbent to effectively remove the composite pollutants according to their characteristics, which is a technical effect that is not envisioned and cannot be achieved by the treatment method of only modifying activated carbon in the prior art.

[0040] 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 in the coastal area. The basic water quality characteristics of the secondary effluent are: an average pH value of 8.17, an average dissolved organic carbon value of 8.21 mg / L, and an average turbidity value of 6.28 NTU; by adding target pollutants, the average concentrations of various pollutants in the sewage are obtained as shown in Table 3.

[0041] The simulated wastewater is treated by the method of the present invention, and the specific steps are as follows: S1: Collect the sewage sample and determine its dissolved organic carbon concentration, which is 5.17 mg / L, i.e. C DOC =5.17 mg / L; the total concentration of the composite pollutants was 11998.17 ng / L, i.e. C HCP =11998.17 ng / L; S2: Determination of the modified aromaticity index (AI) in wastewater mod ) ≥ 0.5 of the dissolved organic matter (DOM) molecules to the total number of dissolved organic matter molecules in the sewage: A total of 11716 DOM molecules were identified, using the formula (1); Calculate the AI ​​of the above molecules mod , the results are as follows Figure 3 As shown; Calculate the modified aromaticity index AI of DOM molecules in water samples mod The proportion of values ​​greater than or equal to 0.5, resulting in P = 15.53%; S3: Based on the ratio of dissolved organic carbon concentration to total concentration of complex pollutants (C DOC / C HCP =431) and P (P=15.53%), select an adsorption column filled with activated carbon and activated carbon modified with limited water in a ratio of 1:1, and the specific operation steps are as follows: (1) The activated carbon was crushed, sieved to 0.3-0.5 mm, washed, and thoroughly dried at 110 °C for 20 h. Then, it was taken out and placed in a constant temperature and humidity chamber at 22.7 °C and 100% humidity for 60 h. After the modification was completed, it was taken out and placed in a constant temperature oven at 40 °C for 15 min. (2) The dual-medium adsorption column is filled with activated carbon and restricted water-modified activated carbon from bottom to top, with a filling ratio of activated carbon: restricted water-modified activated carbon = 1:1; (3) Since the simulation C DOC =5.17 mg / L<20 mg / L, and turbidity =6.28 NTU<10 NTU, which meets the water quality requirements for entering the dual-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.

[0042] The average concentrations of composite pollutants and the effluent risk after treatment of raw water, activated carbon adsorption column, restricted water modified activated carbon adsorption column and dual-media adsorption column are shown in Tables 3 and 4. After treatment with the activated carbon adsorption column (control group 5), the concentration of composite pollutants was reduced by 27~77%, and the overall effluent risk was 0.0665 TU; after treatment with the restricted water modified activated carbon adsorption column (control group 6), the concentration of composite pollutants was reduced by 54~82%, and the overall effluent risk was 0.0422 TU. After upgrading and transforming this method, the dual-media adsorption column with activated carbon: restricted water modified activated carbon = 1:1 was selected. After treatment, the concentration of composite pollutants was reduced by 71~92%, and the overall effluent risk was 0.0199 TU. Therefore, after the modification of this method, the treatment effect was significantly improved. After treatment with the dual-media adsorption column, the overall effluent risk can be significantly reduced. The effluent risk was reduced from 0.0665 TU (activated carbon adsorption column) and 0.0422 TU (limited water modified activated carbon adsorption column) to 0.0121 TU (dual-media adsorption column), respectively, reducing the effluent risk by 70% and 55%, respectively, effectively reducing the risk of complex pollutants in sewage and ensuring effluent safety.

[0043] Table 3 Concentration of composite pollutants in the effluent from adsorption column treatment in Example 2

[0044] Table 4 Total risk of raw water and effluent from adsorption column treatment in Example 2

[0045] In summary, by comparing the control group 4 with Example 2, it can be seen that the method of Example 2 of the present invention has a better adsorption (removal) effect on the composite pollutants. Compared with the control group 4, the removal rate can be increased by 2 to 3 times; the reason is that the adsorption column is used for treatment in Example 2, which shows that the adsorption column of Example 2 can effectively remove the composite pollutants; By comparing control group 5 and 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 rate of various pollutants is 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 2 of the present invention is better. The reason is that the method in Example 2 uses dual-medium adsorbents to effectively remove composite pollutants according to their characteristics, which is a technical effect that is not envisioned and cannot be achieved by the treatment method of only modifying activated carbon in the prior art.

[0046] Example 3: The difference from Example 1 is that the sewage used in this example comes from the secondary effluent of an inland municipal sewage treatment plant. The basic water quality characteristics of the secondary effluent are: the average pH value is 7.67, the average dissolved organic carbon value is 8.70 mg / L, and the average turbidity value is 7.45 NTU; the specific steps are as follows:

[0047] S1: Collect the sewage sample and determine its dissolved organic carbon concentration, which is 7.33 mg / L, namely C DOC =7.33 mg / L; the total concentration of the composite pollutants was 7830.78 ng / L, i.e. C HCP =7830.78 ng / L; S2: Determination of the modified aromaticity index (AI) in wastewater mod ) ≥ 0.5 of the dissolved organic matter (DOM) molecules to the total number of dissolved organic matter molecules in the sewage: A total of 8849 DOM molecules were identified, using the formula (1); Calculate the AI ​​of the above molecules mod , the results are as follows Figure 4 As shown; Calculate the modified aromaticity index AI of DOM molecules in water samples mod The proportion of values ​​greater than or equal to 0.5, P = 21.62%; S3: Based on the ratio of dissolved organic carbon concentration to total concentration of complex pollutants (C DOC / CHCP =936) and P (P=21.62%), select an adsorption column filled with activated carbon and activated carbon modified with limited water in a ratio of 2:1, and the specific operation steps are as follows: (1) The activated carbon was crushed, sieved to 0.3-0.5 mm, washed, and thoroughly dried at 110 °C for 24 h. Then, it was taken out and placed in a constant temperature and humidity chamber at 22.3 °C and 95% humidity for 72 h. After the modification was completed, it was taken out and placed in a constant temperature oven at 30 °C for 20 min. (2) The dual-medium adsorption column is filled with activated carbon and restricted water-modified activated carbon from bottom to top, with a filling ratio of activated carbon: restricted water-modified activated carbon = 2:1; (3) Since the sewage C DOC =7.33 mg / L<20 mg / L, and turbidity =7.45 NTU<10 NTU, which meets the water quality requirements for entering the dual-medium adsorption column; the sewage enters the adsorption column from bottom to top through the peristaltic pump, and the treatment time is 60 min.

[0048] The average concentrations of composite pollutants and the effluent risk after treatment of raw water, activated carbon adsorption column, restricted water modified activated carbon adsorption column and dual-media adsorption column are shown in Table 5 and Table 6, respectively. After treatment with activated carbon adsorption column (control group 8), the concentration of composite pollutants was reduced by 16~45%, and the overall effluent risk was 0.0428 TU; after treatment with restricted water modified activated carbon adsorption column (control group 9), the concentration of composite pollutants was reduced by 21~54%, and the overall effluent risk was 0.0333 TU. After upgrading and transforming this method, the dual-media adsorption column with activated carbon: restricted water modified activated carbon = 2:1 was selected, and the pollutant concentration was reduced by 32~72% after treatment, and the overall effluent risk was 0.0176 TU. Therefore, after the modification of this method, the treatment effect was significantly improved. After treatment with the dual-media adsorption column, the overall effluent risk can be significantly reduced. The effluent risk was reduced from 0.0428 TU (activated carbon adsorption column) and 0.0333 TU (limited water modified activated carbon adsorption column) to 0.0176 TU (dual-media adsorption column), respectively, reducing the effluent risk by 58% and 47%, respectively, significantly reducing the risk of complex pollutants in sewage.

[0049] Table 5 Composite pollutant concentrations in the effluent from adsorption column treatment in Example 3

[0050] Table 6 Total risk of raw water and effluent from adsorption column treatment in Example 3

[0051] In summary, by comparing the control group 7 with the embodiment 3, it can be seen that the adsorption (removal) effect of the composite pollutants by the method of the present invention in the embodiment 3 is better, and the removal rate is much higher than that of the control group 7; the reason is that the adsorption column is used for treatment in the embodiment 3, which shows that the adsorption column of the embodiment 3 can effectively remove the composite pollutants; By comparing control group 8 and control group 9 with Example 3, it can be seen that after the composite pollutants are removed by using Example 3 of the present invention, the removal rate of various pollutants is 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 3 of the present invention is better. The reason is that the method in Example 3 uses dual-medium adsorbents to effectively remove composite pollutants according to their characteristics, which is a technical effect that is not envisioned and cannot be achieved by the treatment method of only modifying activated carbon in the prior art.

[0052] Example 4: The difference from Example 1 is that the preparation method of the limited water modified activated carbon is: first, the activated carbon is crushed, screened, and washed, and then dried at 110°C for 11 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°C and a humidity of 95% for 72 hours for modification; after the modification is completed, it is taken out and placed in a constant temperature oven at 40°C for 15 minutes to obtain limited water modified activated carbon.

[0053] Example 5: The difference from Example 1 is that 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 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 27°C and a humidity of 200% for 40 hours for modification; after the modification is completed, it is taken out and placed in a constant temperature oven at 25°C for 45 minutes to obtain limited water modified activated carbon.

[0054] Example 6: The sewage is effluent from the secondary effluent subsequent process stage (coagulation sedimentation tank), and the sewage is introduced into the adsorption column and left to stand for 30 minutes.

[0055] Example 7: The sewage is effluent from the secondary effluent subsequent process stage (filter cloth filter tank), and the sewage is introduced into the adsorption column and left to stand for 44 minutes.

[0056] Example 8: The sewage is effluent from the secondary effluent subsequent process stage (denitrification filter), and the sewage is introduced into the adsorption column and allowed to stand for 35 minutes.

[0057] Example 9: The sewage is effluent from the secondary effluent subsequent process (UV / ozone disinfection tank), and the sewage is introduced into the adsorption column and left to stand 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, 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.

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: 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.

7. 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.

8. 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.

9. A method for reducing the risk of complex pollutants in sewage as claimed in claim 8, 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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