A method for reducing the content of organic pollutants in coking wastewater concentrate

Abstract

The present invention provides a method for reducing the content of organic pollutants in the concentrated solution of coking wastewater, which belongs to the field of wastewater treatment. The method includes: adding sodium hypochlorite and activated carbon to the concentrated solution of the coking wastewater, so that the ratio of the concentration of the sodium hypochlorite to COD in the concentrated solution is 1:0.5-10; the amount of the activated carbon is 0.5g / L-5g / L; after 1 to 30 seconds of electron beam irradiation treatment, the concentrated solution is left to stand for 30-300 seconds, and finally achieving the purpose of reducing the concentration of organic pollutants in the concentrated solution. The present invention improves the water treatment efficiency by using electron beam irradiation, and synergistically interacts with activated carbon and sodium hypochlorite with electron beam irradiation, thereby effectively reducing the content of organic pollutants in the coking wastewater concentrate without introducing other pollutants.

Description

Technical Field

[0001] The invention relates to the field of wastewater treatment, in particular to a method for reducing the content of organic pollutants in coking wastewater concentrate. Background Art

[0002] my country is a big country in the coking industry, and a large amount of coking wastewater is produced every year, accounting for about 2% of the national industrial wastewater discharge. Coal coking wastewater mainly comes from coking, gas purification, chemical product recovery, refining and other process, and the discharge of wastewater in this process is large. The contents of typical pollutants such as phenol, ammonia nitrogen, CODCr and cyanide in wastewater are 1000-1400 mg / L, 1000-2000 mg / L, 3500-6000 mg / L and 7-70 mg / L respectively. Most of the organic compounds such as phenols and benzene in coal coking wastewater are easily biodegradable, but polycyclic aromatic compounds and heterocyclic compounds such as naphthalene, thiophene, pyridine, quinoline, indole and biphenyl are difficult to biodegrade, and these substances are mutagenic and carcinogenic. Therefore, the treatment of coking wastewater is a difficult problem in the treatment of coal chemical wastewater.

[0003] At present, the combined process of biochemical treatment + nanofiltration + reverse osmosis is widely used to treat coking wastewater, and the effluent water quality can reach the limit specified by the relevant emission standards. However, the water production rate of the membrane system in this combined process is low, and the water recovery rate after nanofiltration and reverse osmosis treatment is usually 50% to 60%. Since the reverse osmosis process only concentrates the pollutants instead of removing them fundamentally, some membrane concentrates with high salt content, high pollutant concentration and poor biochemical performance will be produced. Since the concentrated solution produced contains undegraded organic components and other toxic and harmful substances in the upstream water, the concentrated solution is still a high-concentration organic industrial wastewater that is difficult to biodegrade. Compared with ordinary wastewater, the concentrated solution of coking wastewater has higher conductivity, more complex composition and higher pollutant concentration. Most of the high-concentration pollutants contained in the concentrated solution of coking wastewater have "carcinogenic, teratogenic, mutagenic" effects and toxicity. Direct discharge into the water body may bring risks to ecological safety and human health. Moreover, with the full and mandatory implementation of the new industrial water pollutant emission standards, the concentrated solution needs further treatment to meet the emission standards.

[0004] At present, the following problems exist in the treatment of membrane concentrate of coking wastewater using conventional wastewater treatment technology: the high salinity, especially the high chloride ion content, in the concentrate will quench the active species produced in the advanced oxidation process. For example, chloride ions will react with the generated hydroxyl radicals to form chlorine radicals with weaker oxidizing properties, making it difficult for the traditional advanced oxidation process to achieve the desired effect; at the same time, some advanced oxidation technologies, such as Fenton oxidation, will also introduce other chemicals, which is not conducive to resource recovery; and the evaporation and crystallization method will be used to treat the concentrate, which will produce industrial water and mixed salt. Since the mixed salt contains impurities such as organic matter, it is a hazardous waste and has high disposal costs. Therefore, providing a green and efficient method for treating coking wastewater concentrate is a hot topic in current research. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for reducing the content of organic pollutants in coking wastewater concentrate, aiming to solve the problem of the introduction of impurities or low treatment effect in the current treatment of coking wastewater concentrate. The specific contents are as follows:

[0006] The present invention provides a method for reducing the content of organic pollutants in a coking wastewater concentrate, comprising:

[0007] Adding sodium hypochlorite and activated carbon to the coking wastewater concentrate, so that the ratio of the concentration of sodium hypochlorite to COD in the concentrate is 1:0.5-10; the dosage of the activated carbon is 0.5g / L-5g / L;

[0008] After subjecting the concentrated liquid to electron beam irradiation for 1-30 seconds, the concentrated liquid is allowed to react for 30-300 seconds to obtain a treated liquid with a reduced concentration of organic pollutants;

[0009] Among them, the treated liquid with reduced organic pollutant concentration meets the emission standards.

[0010] Furthermore, the dosage of the activated carbon is 0.5 g / L to 2 g / L, and the activated carbon is granular activated carbon.

[0011] Furthermore, the dosage of the activated carbon is 2 g / L.

[0012] Furthermore, the ratio of the sodium hypochlorite concentration to COD is 1:1-5.

[0013] Furthermore, the ratio of the sodium hypochlorite concentration to COD is 1:1.

[0014] Furthermore, the standing time is 40 to 100 seconds.

[0015] Furthermore, before adding sodium hypochlorite and activated carbon to the coking wastewater concentrate, the method further comprises: adjusting the pH of the coking wastewater to control the pH of the coking wastewater membrane concentrate to be between 3.0 and 11.0.

[0016] Furthermore, the pH adjusting agent includes at least one of polyferric sulfate, concentrated sulfuric acid or sodium hydroxide.

[0017] Furthermore, the irradiation dose of the electron beam irradiation treatment is 5 kGy to 100 kGy.

[0018] Furthermore, the electron beam irradiation treatment is performed using an electron accelerator with an energy ranging from 0.8 MeV to 2.0 MeV.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The invention provides a method for reducing the content of organic pollutants in a coking wastewater concentrate, comprising: adding sodium hypochlorite and activated carbon to the coking wastewater concentrate, so that the ratio of the concentration of sodium hypochlorite to COD in the concentrate is 1:0.5-10; the dosage of the activated carbon is 0.5 g / L-5 g / L; and the concentrate is subjected to electron beam irradiation treatment for 1-30 seconds, and then allowed to react for 30-300 seconds to obtain a treated liquid with reduced organic pollutant concentration.

[0021] Therefore, the present invention uses activated carbon, sodium hypochlorite and electron beam irradiation to synergistically treat the membrane concentrate of coking wastewater; wherein, by utilizing the synergistic effect of electron beam irradiation and sodium hypochlorite, chlorine free radicals and chlorine oxygen free radicals can be directly generated in the coking wastewater, thereby increasing the types of active particles in the electron beam irradiation process, and since chlorine oxygen free radicals and chloride ions will not react with chloride ions in the concentrate, the influence of the quenching effect of chloride ions on the removal of organic pollutants is reduced; and by utilizing the high selectivity of chlorine free radicals and chlorine oxygen free radicals for phenolic pollutants and the characteristics that chlorine free radicals and chlorine oxygen free radicals are less affected by salinity, the treatment effect on phenolic pollutants in wastewater is improved; at the same time, under the action of electron beam irradiation, the surface defects of the added activated carbon increase, thereby improving the adsorption effect of the activated carbon on organic pollutants; and since active groups are generated on the surface of the activated carbon during electron beam irradiation. The active groups can activate the chloroxy ions on the surface of the activated carbon to produce chloroxy free radicals through electron transfer, and can also directly degrade the organic pollutants adsorbed on the surface of the activated carbon through electron transfer, thereby enhancing the treatment of pollutants in the wastewater; therefore, the present invention reduces the concentration of organic pollutants in the coking wastewater concentrate by adding activated carbon, sodium hypochlorite and electron beam irradiation to coordinately treat the coking wastewater membrane concentrate, the process is simple, and the treatment effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of steps of a method for reducing the content of organic pollutants in a coking wastewater concentrate provided by an embodiment of the present invention;

[0023] Figure 2 It is a three-dimensional fluorescence spectrum of the coking wastewater concentrate before and after being treated by the method for reducing the content of organic pollutants in the coking wastewater concentrate according to the embodiment of the present invention; Figure 2 A in the middle is the three-dimensional fluorescence spectrum of the coking wastewater concentrate before treatment; Figure 2 B is a three-dimensional fluorescence spectrum of the treated liquid after being treated by the method for reducing the content of organic pollutants in the coking wastewater concentrate according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0025] Coking wastewater refers to the wastewater generated during coal coking, coal gas purification, chemical product recovery and chemical product refining. Its main sources are the initial cooling of coke oven gas and the production water used in the coking production process, as well as steam condensation wastewater. Coking wastewater is a typical toxic and difficult to degrade organic wastewater. How to ensure that the effluent water quality of coking wastewater meets the discharge standards is a hot topic and difficulty in current research.

[0026] At present, the treatment of coking wastewater usually adopts a combination of biochemical treatment, nanofiltration and reverse osmosis, and the effluent water quality can meet the relevant emission standards. Among them, after the coking wastewater is treated with reverse osmosis, a coking wastewater membrane concentrate will be produced. The concentrate has the characteristics of high salinity, high concentration of organic pollutants and poor biodegradability. In a high-salt environment, chloride ions will react with active particles such as hydroxyl radicals in advanced oxidation technology to obtain chlorine radicals. Since the oxidizing property of chlorine radicals is lower than that of hydroxyl radicals, the removal effect of organic pollutants will be reduced; and the microorganisms commonly used in biochemical treatment have low activity in a high-salt environment, and it is also difficult to remove organic pollutants; therefore, it is difficult for common advanced oxidation technology and biochemical treatment to produce a good treatment effect on coking wastewater membrane concentrate.

[0027] Existing treatment methods for membrane concentrate of coking wastewater usually include mechanical evaporation, multiple combined processes, etc. However, although mechanical evaporation can reduce the amount of membrane concentrate, it has high energy consumption. Due to the presence of organic pollutants in the salt formed after evaporation, its purity cannot meet the requirements of industrial reuse. If it is only treated as solid waste, it will inevitably increase the treatment cost, and the recyclable resources therein cannot be recovered, resulting in resource waste; multiple combined processes are usually used to treat them in sequence using physicochemical treatment methods such as electrochemical oxidation and Fenton oxidation. The treatment process is complicated and other chemical substances need to be introduced. For example, the commonly used three-dimensional electro-oxidation-photo-Fenton-electrocatalytic oxidation combined process and flocculation-Fenton oxidation-electrocatalytic oxidation combined process require multiple oxidation processes and the introduction of iron impurities for treatment. The treatment process is complicated and will cause impurity problems in the recovered salt.

[0028] In view of this, the present invention proposes a treatment method for reducing the content of organic pollutants in coking wastewater concentrate; the coking wastewater concentrate is treated by electron beam irradiation in coordination with sodium hypochlorite and activated carbon, and the characteristics of electron beam irradiation compared with conventional water treatment technology are utilized, which has stronger wastewater treatment capacity and higher treatment efficiency and does not require the addition of other chemical substances. The electron beam irradiation process is used as the main treatment technology for coking wastewater concentrate, and activated carbon and sodium hypochlorite are added to cooperate with electron beam irradiation to increase the types of active particles in the coking wastewater concentrate during the treatment process, reduce the quenching effect of high salinity on active particles generated by irradiation, and improve the treatment efficiency of organic pollutants in a high-salt environment.

[0029] Among them, the added sodium hypochlorite generates chlorine oxygen free radicals through electron beam irradiation, which can still selectively remove organic pollutants in a high-salt environment. The added activated carbon increases its adsorption of organic pollutants as the electron beam irradiation proceeds, thereby improving the treatment efficiency of organic pollutants in a high-salt environment. The present invention treats the coking wastewater concentrate by electron beam irradiation in coordination with sodium hypochlorite and activated carbon, thereby reducing the content of organic pollutants in the coking wastewater; compared with the combination method of multiple processes in the prior art, the method provided by the present invention is simpler and easier to implement, while reducing the content of organic pollutants in the coking wastewater concentrate, because the added sodium hypochlorite finally obtains chloride ions and sodium ions, the added activated carbon can be directly removed by filtration, and no other chemical substances are actually introduced. After subsequent treatment, salt with higher purity can be obtained, which facilitates the resource recovery process.

[0030] A method for reducing the content of organic pollutants in a concentrated solution of coking wastewater provided by the present invention is specifically introduced below in conjunction with the accompanying drawings.

[0031] Reference Figure 1 , Figure 1A flow chart showing the steps of a method for reducing the content of organic pollutants in a coking wastewater concentrate provided by an embodiment of the present invention is shown as follows: Figure 1 As shown, the method includes:

[0032] S101, adding sodium hypochlorite and activated carbon to the coking wastewater concentrate, so that the ratio of the concentration of sodium hypochlorite to COD in the concentrate is 1:0.5-10; and the dosage of the activated carbon is 0.5 g / L-5 g / L.

[0033] Among them, the coking wastewater concentrate is obtained by treating the coking wastewater with a membrane process, and its main characteristics are high salinity and high organic pollutant concentration. The membrane process is a commonly used method for treating coking wastewater. The reverse osmosis membrane process used in the relevant technology includes: pretreatment + ultrafiltration membrane (UF) + reverse osmosis membrane (RO) process, pretreatment + membrane bioreactor (MBR) + reverse osmosis membrane (RO) process, and pretreatment + ultrafiltration membrane (UF) + nanofiltration membrane (NF) + reverse osmosis membrane (RO) process. The embodiment of the present invention does not specifically limit the type of membrane process method used, and it is sufficient to obtain the coking wastewater concentrate.

[0034] Among them, the pretreatment method may include Fenton oxidation, electrochemical oxidation, ozone oxidation and other pretreatment methods; the coking wastewater may also be pretreated by electron beam irradiation to reduce the concentration of organic pollutants therein; the specific pretreatment method is determined according to the actual situation of the coking wastewater, and the present invention does not make any specific restrictions.

[0035] Among them, nanofiltration membrane refers to a treatment method that uses nanofiltration membrane to separate pollutants. Nanofiltration membrane refers to a semi-permeable membrane with a pore size of more than 1nm, generally 1-2nm. Its ability to intercept dissolved salts is between 20% and 98%. The removal rate of soluble monovalent ions is lower than that of high-valent ions. Nanofiltration is generally used to remove organic matter and pigments in surface water, hardness and radium in groundwater, and partially remove dissolved salts. It uses nanofiltration technology, a pressure-driven membrane separation technology between reverse osmosis and ultrafiltration. The separation mechanism of nanofiltration membrane is the coexistence of screening and dissolution diffusion, and it also has a charge repulsion effect. It can effectively remove divalent and multivalent ions, remove various substances with a molecular weight greater than 200, and partially remove monovalent ions and substances with a molecular weight less than 200.

[0036] Ultrafiltration membrane refers to a treatment method that separates pollutants through ultrafiltration membrane; the ultrafiltration technology it uses is a membrane separation technology between microfiltration and nanofiltration, with an average pore size of 3 to 100nm, and has the functions of purifying, separating, and concentrating solutions. Its interception mechanism mainly includes the screening effect and electrostatic effect of the membrane. The filter medium is the ultrafiltration membrane. Driven by the pressure difference on both sides, only low molecular weight solutes and water can pass through the ultrafiltration membrane, thereby achieving the purpose of purification, separation, and concentration.

[0037] Membrane bioreactor is a new and highly efficient sewage treatment technology that combines membrane separation and biological treatment. Almost all microorganisms can be trapped in the bioreactor, which increases the biological concentration in the reactor. Theoretically, the sludge age can be infinitely long, the organic matter content in the effluent is reduced to the minimum, and the ammonia nitrogen in the wastewater is effectively removed.

[0038] The dosage of sodium hypochlorite is related to the concentration of organic pollutants in the wastewater. Therefore, the dosage of sodium hypochlorite is determined according to the COD (Chemical Oxygen Demand) of the coking wastewater concentrate. The added sodium hypochlorite can be solid particles or solution. If the sodium hypochlorite is solid particles, the mass of the added sodium hypochlorite is directly determined according to the initial concentration after the addition of sodium hypochlorite. If the sodium hypochlorite is a solution, the amount of sodium hypochlorite solution to be added is determined according to the solution of sodium hypochlorite and the initial concentration after the addition of sodium hypochlorite. Among them, the ratio of the dosage of sodium hypochlorite to COD is 1:0.5~10.

[0039] For example, the ratio of the dosage of sodium hypochlorite to COD is 1:0.5;

[0040] The ratio of the dosage of sodium hypochlorite to COD is 1:2;

[0041] The ratio of the dosage of sodium hypochlorite to COD is 1:4;

[0042] The ratio of the dosage of sodium hypochlorite to COD is 1:6;

[0043] The ratio of the dosage of sodium hypochlorite to COD is 1:8.

[0044] Activated carbon is mainly used to adsorb organic pollutants in coking wastewater. Its dosage is also related to the content of organic pollutants in the coking wastewater concentrate. In the embodiment of the present invention, the dosage of activated carbon is usually between 0.5g / L and 5g / L.

[0045] For example, the dosage of the activated carbon is 1 g / L;

[0046] The dosage of the activated carbon is 1.5 g / L;

[0047] The dosage of the activated carbon is 2 g / L;

[0048] The dosage of the activated carbon is 4 g / L.

[0049] In some feasible embodiments, since the activated carbon is reusable, when it is needed, the activated carbon filtered out after the previous treatment can be irradiated with electron beam to quickly restore the activity of the activated carbon; wherein, the reuse time of the activated carbon is determined according to the actual situation, such as after 10 days of reuse, or after a fixed number of reuses, new activated carbon can be added. wherein, the activated carbon can be in powder or granular form.

[0050] Preferably, granular activated carbon is used to treat the coking wastewater concentrate, because the defects formed in the granular activated carbon during the electron beam irradiation process are large and easy to separate.

[0051] Preferably, the ratio of the dosage of sodium hypochlorite to COD is 1: 1. This is because, although both chlorine oxygen free radicals and hydroxyl free radicals are active particles, their actual oxidation capabilities are different, and the oxidation performance of hydroxyl free radicals is better. Therefore, if the dosage of sodium hypochlorite is too much, it will affect the generation of active particles such as hydroxyl free radicals and reduce the treatment capacity of organic pollutants.

[0052] Preferably, the dosage of activated carbon is 2g / L; this is because the dosage of activated carbon is determined according to the concentration of organic pollutants. If the dosage of activated carbon is too much, some of the activated carbon will not play a role in adsorbing organic pollutants, and there may be a situation where the activated carbon with high activity is discarded, resulting in a waste of resources; and if the dosage of activated carbon is too low, it is difficult to achieve the effect of adsorbing organic pollutants, or the adsorption effect is poor, and the removal effect of organic pollutants is limited.

[0053] In some feasible embodiments, since the pH of the treatment reaction of the coking wastewater concentrate is between 3 and 11, before the coking wastewater concentrate is treated, the pH of the coking wastewater concentrate needs to be tested to determine whether its pH is between 3 and 11. If the test result shows that the wastewater pH is less than 3 or greater than 11, the pH of the coking wastewater concentrate needs to be adjusted in advance to control the pH of the coking wastewater concentrate to between 3 and 11. The pH regulator generally includes at least one of polyferric sulfate, concentrated sulfuric acid or sodium hydroxide.

[0054] Among them, the regulator for adjusting the pH of the coking wastewater concentrate can be a commonly used acid, alkali, salt or buffer solution, etc. The regulator selected in the embodiment of the present invention is concentrated sulfuric acid, sodium hydroxide or polyferric sulfate; wherein, the iron ions in the polyferric sulfate can form a colloid to adsorb organic pollutants in the coking wastewater concentrate, thereby, some organic pollutants can be removed by flocculation, and at the same time, the dissolution of polyferric sulfate can produce a small amount of Fe(II), and Fe(II) can activate the hydrogen peroxide produced during the electron beam irradiation process to produce active particles, thereby further enhancing the electron beam irradiation ability to treat organic pollutants.

[0055] S102, after subjecting the concentrated liquid to electron beam irradiation treatment for 1 to 30 seconds, the concentrated liquid is allowed to react for 30 to 300 seconds to obtain a treated liquid with a reduced concentration of organic pollutants.

[0056] For example, the concentrated solution is subjected to electron beam irradiation treatment for 1 second, and then allowed to react for 30 seconds to obtain a treated solution with a reduced concentration of organic pollutants;

[0057] After subjecting the concentrated solution to electron beam irradiation for 5 seconds, the concentrated solution is allowed to react for 100 seconds to obtain a treated solution with a reduced concentration of organic pollutants;

[0058] After subjecting the concentrated solution to electron beam irradiation for 10 seconds, the concentrated solution is allowed to react for 150 seconds to obtain a treated solution with a reduced concentration of organic pollutants;

[0059] After subjecting the concentrated solution to electron beam irradiation for 20 seconds, the concentrated solution is allowed to react for 200 seconds to obtain a treated solution with a reduced concentration of organic pollutants;

[0060] After subjecting the concentrated solution to electron beam irradiation for 30 seconds, the concentrated solution is allowed to react for 250 seconds to obtain a treated solution with a reduced concentration of organic pollutants;

[0061] The concentrated solution is subjected to electron beam irradiation treatment for 30 seconds, and then allowed to stand for reaction for 300 seconds to obtain a treated solution with a reduced concentration of organic pollutants.

[0062] In the embodiment of the present invention, the irradiation dose of electron beam irradiation is 50-100 kGy, and the irradiation time is 1-30 s; after the coking wastewater concentrate is irradiated, the coking wastewater concentrate is allowed to react for a period of time to treat the organic pollutants in the coking wastewater concentrate; wherein the COD of the treated liquid after treatment is below 120 mg / L, and the TOC is below 30 mg / L.

[0063] For example, the irradiation dose of electron beam irradiation is 50 kGy;

[0064] The irradiation dose of electron beam irradiation was 75 kGy;

[0065] The irradiation dose of electron beam irradiation was 100 kGy.

[0066] Among them, since electron beam irradiation actually produces active particles through the direct action of high-energy electron beams and the excitation of water by high-energy electron beams, the energy generated is relatively high, and more active particles can be produced in a short irradiation time. Therefore, the electron beam irradiation time is generally short, within 1 to 30 seconds.

[0067] Specifically, the electron beam irradiation treatment is carried out using an electron accelerator, wherein the energy of the electron accelerator is between 0.8 MeV and 2.0 MeV; thus, a high-energy electron accelerator can produce a large irradiation dose in a short time, thus avoiding the problem of high costs caused by long-term electron beam irradiation.

[0068] For example, the energy of the electron accelerator is 0.8 MeV;

[0069] The energy of the electron accelerator is 1.5 MeV;

[0070] The energy of the electron accelerator is 2.0 MeV.

[0071] The embodiment of the present invention adds sodium hypochlorite and activated carbon to the coking wastewater concentrate, and synergizes with electron beam irradiation to improve the treatment capacity of the coking wastewater concentrate, reduce the content of organic pollutants in the coking wastewater concentrate, facilitate subsequent treatment, and do not introduce other chemical substances during the treatment process, which is convenient for subsequent recovery of salt and avoids waste of resources. On the one hand, sodium hypochlorite can produce chlorine oxygen free radicals during electron beam irradiation, increase the types of active particles in the coking wastewater concentrate, and because the chlorine oxygen free radicals do not react with the chloride ions in the coking wastewater concentrate, that is, the chloride ions will not quench the chlorine oxygen free radicals, thereby increasing the active substances in the treatment process and improving the treatment capacity of the coking wastewater concentrate by electron beam irradiation. On the other hand, the added activated carbon has more surface defect sites during electron beam irradiation, thereby enhancing the adsorption of organic pollutants by the activated carbon. In addition, during the electron beam irradiation process, chloride ions can be directly activated into chlorine free radicals, and chlorine free radicals have strong selectivity for phenolic organic pollutants, and the chlorinated products generated after the reaction can be adsorbed by activated carbon, thereby reducing the influence of chloride ions in the coking wastewater concentrate and improving the treatment effect of electron beam irradiation on the coking wastewater concentrate; therefore, the present invention reduces the content of organic pollutants in the coking wastewater concentrate by adding activated carbon, sodium hypochlorite and electron beam irradiation to coordinately treat the coking wastewater membrane concentrate, and the process is simple and the treatment effect is good.

[0072] In order to enable those skilled in the art to better understand the present invention, a method for reducing the content of organic pollutants in a coking wastewater concentrate of the present invention is described below through a plurality of specific embodiments.

[0073] Embodiment 1:

[0074] The coking wastewater concentrate produced by a coking plant after biochemical treatment, ozone oxidation, ultrafiltration and reverse osmosis membrane treatment was tested. The initial COD of the coking wastewater concentrate was 190±17 mg / L, the initial TOC was 52.5±3.7 mg / L, the salt content was about 2%, and the pH was 6.7.

[0075] A certain amount of sodium hypochlorite and activated carbon were added to the wastewater so that the initial concentrations of sodium hypochlorite and activated carbon were 0.2 g / L and 1.0 g / L, respectively.

[0076] The obtained mixed solution was irradiated by an electron accelerator with an irradiation dose of 10 kGy; and then allowed to react for 100 seconds to obtain a treated solution with a reduced content of organic pollutants.

[0077] After testing, the COD of the treated liquid was 104±27mg / L, and the TOC was 27.4±1.4mg / L.

[0078] Example 2

[0079] The coking wastewater concentrate produced by a coking plant after biochemical treatment, ozone oxidation, ultrafiltration and reverse osmosis membrane treatment was tested. The initial COD of the coking wastewater concentrate was 190±17 mg / L, the initial TOC was 52.5±3.7 mg / L, the salt content was about 2%, and the pH was 6.7.

[0080] Add a certain amount of sodium hypochlorite and activated carbon to the wastewater, so that the initial concentrations of sodium hypochlorite and activated carbon are 0.3g / L and 0.5g / L respectively. 60 The obtained mixed solution was irradiated by Co for 10 seconds, wherein the irradiation dose was 20 kGy; and then allowed to react for 120 seconds to obtain a treated solution with reduced organic pollutant content.

[0081] After testing, the COD of the treated liquid was 92±11 mg / L and the TOC was 24.6±2.7 mg / L.

[0082] Example 3

[0083] The coking wastewater concentrate from a coking plant was taken after biochemical treatment, Fenton oxidation, ultrafiltration and reverse osmosis membrane treatment. After testing, the initial COD of the coking wastewater concentrate was 210±14 mg / L, the initial TOC was 52.5±3.7 mg / L, the salt content was about 2%, and the pH was 7.3.

[0084] Add appropriate amounts of sodium hypochlorite and activated carbon to the wastewater so that the initial concentrations of sodium hypochlorite and activated carbon are 0.2 g / L and 2.0 g / L, respectively.

[0085] use 60 The obtained mixed solution was irradiated with Co at a dose of 10 kGy, and then allowed to react for 300 s to obtain a treated solution with reduced organic pollutant content.

[0086] After testing, the COD of the treated liquid was 107±19 mg / L, and the TOC was 30.7±2.4 mg / L.

[0087] Example 4

[0088] Take the coking wastewater concentrate after biochemical treatment, Fenton oxidation, ultrafiltration and reverse osmosis membrane process in a certain coking plant; after testing, the initial COD of this coking wastewater concentrate is 210±14mg / L, the salt content is about 2%, and the pH is 7.3.

[0089] Add appropriate amounts of sodium hypochlorite and activated carbon to the wastewater so that the initial concentrations of sodium hypochlorite and activated carbon are 0.1g / L and 2.0g / L respectively.

[0090] Use an electron accelerator to carry out radiation reaction on the obtained mixed solution, and the irradiation dose is 50kGy; then let it stand and react for 200s to obtain a treatment solution with reduced organic pollutant content.

[0091] After testing, the COD of the treatment solution after treatment is 87±7mg / L.

[0092] Use a three-dimensional fluorescence spectrometer to detect the coking wastewater concentrate before and after treatment, and the detection results are as Figure 2 shown. The components of the coking wastewater concentrate before and after treatment have changed significantly. As can be seen from Figure 2 A, the coking wastewater concentrate before treatment is mainly composed of dissolved microbial by-products (250nm < EX < 280nm, EM < 380nm). And according to Figure 2 B, it can be seen that the dissolved microbial by-products in the reverse osmosis membrane concentrate after treatment basically disappear. The change of the components of the coking wastewater concentrate before and after treatment further proves that the electron beam irradiation coupled with the sodium hypochlorite / activated carbon process can effectively treat the organic pollutants in the reverse osmosis membrane concentrate.

[0093] Comparative Example 1

[0094] Take the coking wastewater concentrate produced after biochemical treatment, ozone oxidation, ultrafiltration and reverse osmosis membrane process in a certain coking plant. After testing, the initial COD of this coking wastewater concentrate is 190±17mg / L, the initial TOC is 52.5±3.7mg / L, the salt content is about 2%, and the pH is 6.7.

[0095] Use an electron accelerator to carry out radiation treatment on the obtained mixed solution, and the irradiation dose is 10kGy; then let it stand and react for 100s to obtain a treatment solution with reduced organic pollutant content.

[0096] After testing, the COD of the treatment solution after treatment is 181±4mg / L, and the TOC is 51.1±1.7mg / L.

[0097] It can be seen from the above embodiments that the method for reducing the content of organic pollutants in coking wastewater concentrate of the present invention is used to treat the coking wastewater concentrate. The coking wastewater concentrate is treated by sodium hypochlorite and activated carbon in coordination with electron beam irradiation, which can effectively improve the treatment effect of electron beam irradiation treatment of the coking wastewater concentrate. Compared with only electron beam irradiation treatment, the treatment effect of organic pollutants is improved.

[0098] Among them, the coking wastewater with sodium hypochlorite added by electron beam irradiation can directly generate chlorine free radicals and chlorine oxygen free radicals in the water, thereby increasing the types of active particles in the electron beam irradiation process, and because the chlorine oxygen free radicals and chloride ions will not react with the chloride ions in the concentrated solution, the influence of the quenching effect of chloride ions on the removal of organic pollutants is reduced; and the high selectivity of chlorine free radicals and chlorine oxygen free radicals for phenolic pollutants and the characteristics that chlorine free radicals and chlorine oxygen free radicals are less affected by salinity are utilized to improve the treatment effect of phenolic pollutants in wastewater; at the same time, under the action of electron beam irradiation, The surface defects of the activated carbon introduced are increased, thereby improving the adsorption effect of the activated carbon on organic pollutants; and because the activated carbon also generates active groups on its surface when irradiated with electron beams, the active groups can activate the chlorine oxides adsorbed on its surface to generate active particles through electron transfer, and can directly degrade the organic pollutants adsorbed on the surface, thereby enhancing the treatment of pollutants in the wastewater; therefore, the present invention reduces the content of organic pollutants in the coking wastewater concentrate by adding activated carbon, sodium hypochlorite and electron beam irradiation to coordinately treat the coking wastewater membrane concentrate, the process is simple, and the treatment effect is good.

[0099] The embodiment of the present invention adds sodium hypochlorite and activated carbon to the coking wastewater concentrate, and synergistically acts with electron beam irradiation to improve the treatment capacity of the coking wastewater concentrate, reduce the content of organic pollutants in the coking wastewater concentrate, and facilitate subsequent treatment. In addition, no other chemical substances are introduced during the treatment process, which facilitates the subsequent recovery of salt and avoids waste of resources.

[0100] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0101] The above is a detailed introduction to a method for reducing the content of organic pollutants in coking wastewater provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technicians in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for reducing the content of organic pollutants in a coking wastewater concentrate, characterized in that: The method comprises: Adding sodium hypochlorite and activated carbon to the coking wastewater concentrate, so that the ratio of the concentration of sodium hypochlorite to COD in the concentrate is 1:0.5-10; the dosage of the activated carbon is 0.5 g / L-5 g / L; After subjecting the concentrated solution to electron beam irradiation for 1 to 30 seconds, the concentrated solution is allowed to react for 30 to 300 seconds to obtain a treated solution with a reduced concentration of organic pollutants; The coking wastewater concentrate is obtained by treating coking wastewater with a membrane process, and has the characteristics of high salinity and high concentration of organic pollutants. The activated carbon generates active groups during the electron beam irradiation treatment, and the active groups activate the chlorine oxides on the surface of the activated carbon through electron transfer to generate chlorine oxide free radicals, and degrade the organic pollutants adsorbed on the surface of the activated carbon through electron transfer. The irradiation dose of the electron beam irradiation treatment is 5 kGy to 100 kGy.

2. The method for reducing the content of organic pollutants in coking wastewater concentrate according to claim 1, characterized in that: The dosage of the activated carbon is 0.5 g / L~2 g / L, and the activated carbon is granular activated carbon.

3. The method for reducing the content of organic pollutants in coking wastewater concentrate according to claim 2, characterized in that: The dosage of the activated carbon is 2 g / L.

4. The method for reducing the content of organic pollutants in coking wastewater concentrate according to claim 1, characterized in that: The ratio of the sodium hypochlorite concentration to COD is 1:1-5.

5. The method for reducing the content of organic pollutants in coking wastewater concentrate according to claim 4, characterized in that: The ratio of the sodium hypochlorite concentration to COD is 1:

1.

6. The method for reducing the content of organic pollutants in coking wastewater concentrate according to claim 1, characterized in that: The static reaction time is 40-100s.

7. The method for reducing the content of organic pollutants in coking wastewater concentrate according to claim 1, characterized in that: Before adding sodium hypochlorite and activated carbon to the coking wastewater concentrate, the method further comprises: The pH of the coking wastewater concentrate is adjusted to control the pH of the coking wastewater concentrate to be between 3.0 and 11.

0.

8. The method for reducing the content of organic pollutants in coking wastewater concentrate according to claim 7, characterized in that: The pH regulator includes at least one of polyferric sulfate, concentrated sulfuric acid or sodium hydroxide.

9. The method for reducing the content of organic pollutants in coking wastewater concentrate according to claim 1, characterized in that: The electron beam irradiation treatment is performed using an electron accelerator; the energy of the electron accelerator is between 0.8 MeV and 2.0 MeV.

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