A method and system for reducing the color of coking wastewater concentrate

Abstract

This invention provides a method and system for reducing the color of coking wastewater concentrate, belonging to the field of wastewater treatment. It aims to solve the problems of incomplete decolorization and easy color reversion that exist when using advanced oxidation methods to decolorize coking wastewater concentrate. The method includes: Step 1, adding persulfate to the wastewater to carry out a first-step reaction, obtaining a primary treated liquid; Step 2, transferring the primary treated liquid to an irradiation device for irradiation treatment, obtaining a secondary treated liquid; Step 3, collecting the ozone generated in the irradiation device and the secondary treated liquid respectively, and introducing the ozone into the secondary treated liquid, and adding ferrous salt, to carry out a final reaction, so that the color of the wastewater is reduced to less than 10 times.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method and system for reducing the color of coking wastewater concentrate. Background Technology

[0002] Color refers to the degree of yellowish or brownish hue exhibited by dissolved or colloidal substances in water. Natural water generally appears pale yellow, pale brown, or yellowish-green, primarily due to the decay and decomposition of dead plants and animals, and mainly contains organic and inorganic matter. The color of industrial wastewater or domestic sewage, however, is more often caused by substances with chromogenic functional groups. The color of this wastewater is determined by the concentration of pollutants it contains. Color is one of the main pollution indicators, signifying the degree of water pollution. Discharging or directly recycling polluted water undoubtedly impacts the environment and human health.

[0003] The coal chemical industry generates coking wastewater during production. Coking wastewater is characterized by large volume, complex water quality, and high levels of organic pollutants, making it a type of recalcitrant industrial wastewater. Many coal chemical enterprises use a dual-membrane process of "ultrafiltration + reverse osmosis." This process produces a concentrate. The concentrate contains high concentrations of organic matter and salinity. Taking coking wastewater as an example, the organic matter in the wastewater contains a large amount of chromogenic groups such as kunzides and nitrogen-containing functional groups, resulting in a deep yellow, or even soy sauce-colored, color in the concentrate. Effectively destroying the chromogenic functional groups of organic pollutants and removing the color from the concentrate remains a major challenge.

[0004] Currently, the main methods for removing color from water include: adsorption decolorization, flocculation decolorization, oxidation decolorization, biological decolorization, electrochemical decolorization, and membrane separation decolorization. Among these methods, adsorption decolorization removes color by adsorbing chromogenic groups in water with adsorbents; however, it requires specialized treatment facilities and incurs high costs. Flocculation decolorization removes colloidal suspended solids in water by using coagulants for surface charge neutralization, bonding, bridging, and trapping; however, it typically requires large dosages and has high reagent costs. Biological decolorization uses microbial enzymes to oxidize or reduce colored molecules to achieve decolorization; however, biological decolorization requires microorganisms, which have specific growth requirements, necessitating wastewater pretreatment to meet these requirements. Electrochemical decolorization removes color from wastewater through electrode reactions. Membrane separation decolorization uses synthetic or natural polymer membranes, driven by external energy or chemical potential differences, to selectively separate pollutants in water. Oxidative decolorization typically uses oxidants and other active substances to decolorize wastewater. Among these, advanced oxidation methods are widely used in industrial wastewater treatment due to their rapid reaction and good color removal effect. Advanced oxidation is a method of decolorizing wastewater by using active species generated in the system to destroy chromogenic groups. Its decolorization effect depends on the activity and amount of active species generated.

[0005] However, for coking wastewater concentrate containing a large amount of salts, the salts can quench the active species generated in the system, resulting in poor decolorization effect of advanced oxidation methods on coking wastewater concentrate. Usually, a large amount of oxidant needs to be added to achieve the purpose of decolorization, but this method will lead to a sharp increase in cost, and the addition of a large amount of chemical substances will introduce additional chemical substances into the system, resulting in low purity of the by-salt obtained after desalination.

[0006] Therefore, there is an urgent need to develop a wastewater decolorization method that requires less oxidant, has good treatment effect, and is low in cost. Summary of the Invention

[0007] In view of this, the present invention aims to propose a method and system for reducing the color of coking wastewater concentrate, so as to solve the problems of poor color removal effect and color return that exist in the current advanced oxidation decolorization method.

[0008] A first aspect of the present invention provides a method for reducing the color of coking wastewater concentrate, the method comprising:

[0009] Step 1: Add persulfate to the coking wastewater concentrate to carry out the first step reaction and obtain the primary treatment solution;

[0010] Step 2: Transfer the primary treatment solution to an irradiation device for irradiation treatment to obtain a secondary treatment solution;

[0011] Step 3: Collect the ozone generated in the irradiation device and the secondary treatment liquid respectively, and introduce the ozone into the secondary treatment liquid and add ferrous salt to carry out the final reaction, so as to reduce the color of the coking wastewater concentrate to less than 10 times.

[0012] Furthermore, in step 3, after the final reaction, the method further includes:

[0013] Flocculants or activated carbon are added to the concentrated coking wastewater to remove iron from the wastewater.

[0014] Furthermore, in step 1, the ratio of the amount of persulfate added to the COD in the coking wastewater concentrate is 0.1-0.5:1, and the reaction time of the first step reaction is 10-40 min.

[0015] Furthermore, the irradiation dose of the irradiation treatment is 1-4 kGy.

[0016] Furthermore, in step 3, the dosage of the ferrous salt is 75-350 mg / L.

[0017] Furthermore, the ferrous salt is either ferrous sulfate or ferrous chloride.

[0018] Furthermore, the concentration of chloride ions in the concentrate is greater than or equal to 1 g / L.

[0019] Furthermore, the irradiation treatment is electron beam irradiation, which is performed using an electron accelerator.

[0020] In a second aspect, the present invention provides a system for reducing the color of wastewater to solve the problems of poor color removal and color reversion that exist in current advanced oxidation decolorization methods.

[0021] A system for reducing the color of coking wastewater concentrate, used to achieve the method for reducing the color of coking wastewater concentrate as described in the first aspect above, the system comprising:

[0022] The apparatus comprises a first reaction device, an irradiation device, a second reaction device, and a gas collection device;

[0023] The first reaction device is connected to the irradiation device, and the irradiation device is connected to the second reaction device in sequence via a wastewater transport pipeline.

[0024] The irradiation device is provided with an inlet and an outlet. The outlet is connected to the gas collection device, and the gas collection device is connected to the second reaction device through a gas delivery pipeline.

[0025] Furthermore, the gas delivery pipe extends into the interior of the second reaction device, and the gas outlet of the gas delivery pipe is located near the inner bottom of the second reaction device.

[0026] The system for reducing the color of coking wastewater concentrate described above has the same advantages over existing technologies as the methods for reducing the color of coking wastewater concentrate described above, and will not be elaborated here.

[0027] The method for reducing the color of coking wastewater concentrate provided by this invention has the following advantages over existing technologies:

[0028] The method for reducing the color of coking wastewater concentrate provided by the present invention includes: Step 1, adding persulfate to the wastewater to carry out a first-step reaction to obtain a primary treated liquid; Step 2, transferring the primary treated liquid to an irradiation device for irradiation treatment to obtain a secondary treated liquid; Step 3, collecting the ozone and the secondary treated liquid generated in the irradiation device respectively, and introducing the ozone into the secondary treated liquid and adding ferrous salt to carry out a final reaction to reduce the color of the wastewater to less than 10 times.

[0029] Therefore, by sequentially employing persulfate, irradiation, ozone, and ferrous salt for wastewater treatment, the persulfate reacts with chloride ions in the water to produce hypochlorous acid and singlet oxygen, thus removing color. Subsequently, electron beam irradiation generates ozone and hypochlorous acid radicals in the water, further removing color. Then, ferrous salt is added, and the ferrous ions react with hypochlorous acid and hydrogen peroxide generated during irradiation to produce high-valence iron, further removing color. Thus, through the synergistic effect of persulfate, electron beam irradiation, ozone, and high-valence iron, the reaction process... The process achieves a more thorough removal of color. Simultaneously, because the ozone generated in the irradiation device is collected and reintroduced into the wastewater during the reaction, the utilization rate of active substances generated during irradiation is improved, while also solving the problem of residual ozone disposal. Furthermore, due to the change in the valence state of some chloride ions during the reaction, the inhibitory effect of chloride ions is reduced, while promoting the generation of highly selective active species such as hypochlorous acid and ferric iron. Therefore, this method has a good removal effect on the color of coking wastewater concentrate. Attached Figure Description

[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0031] Figure 1 A flowchart illustrating the steps of a method for reducing the color of coking wastewater concentrate provided in an embodiment of the present invention is shown.

[0032] Figure 2A schematic diagram of the system for reducing the color of coking wastewater concentrate provided in an embodiment of the present invention is shown. Detailed Implementation

[0033] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. Where specific experimental steps or conditions are not specified in the embodiments, the conventional experimental steps or conditions described in the prior art can be followed. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products.

[0034] Currently, due to the high color content in industrial wastewater, especially dyeing and printing wastewater and coking wastewater, color removal has become an indispensable part of wastewater treatment. The main color removal methods used in industrial wastewater treatment include: adsorption decolorization, flocculation decolorization, oxidation decolorization, biological decolorization, electrochemical decolorization, and membrane separation decolorization. Among these, oxidation decolorization is a relatively mature process and is widely used in industrial wastewater treatment.

[0035] However, the current oxidation decolorization methods, especially advanced oxidation methods, suffer from unsatisfactory treatment effects and color reversion when applied to the treatment of coking wastewater concentrate. This is because the active species generated by advanced oxidation are easily quenched by salts in a high-salt environment.

[0036] In view of this, the present invention provides a method and system for reducing the color of coking wastewater concentrate. First, persulfate is applied to the coking wastewater concentrate to generate hypochlorous acid from chloride ions in the wastewater, and singlet oxygen is generated, thus removing color. Then, the wastewater is irradiated with an electron beam, utilizing hypochlorite ions in the wastewater to generate hypochlorite free radicals, and ozone generated during the irradiation process to further remove color. The ozone generated during irradiation is then collected and reintroduced into the wastewater, where ferrous ions are added to react. The high-valence iron formed by the reaction of ferrous ions and hypochlorous acid in the wastewater, along with ozone and other active species, work together to remove color. Thus, through the synergistic effect of multiple oxidizing substances, the color of the coking wastewater concentrate can be reduced to less than 10 times, allowing for direct recycling. Furthermore, by fully utilizing the synergistic effect of multiple oxidizing substances during the treatment process, the dosage of oxidizing substances is significantly reduced, significantly improving the color removal effect while lowering treatment costs.

[0037] The present invention provides a method and system for reducing wastewater color, which will be described in detail below with reference to the accompanying drawings and embodiments.

[0038] In a first aspect, the present invention provides a method for reducing the color of coking wastewater concentrate, in order to solve the problems of poor decolorization effect and color return in the current wastewater decolorization method using oxidation.

[0039] Reference Figure 1 , Figure 1 A flowchart illustrating the steps of a method for reducing the color of coking wastewater concentrate according to an embodiment of the present invention is shown, as follows: Figure 1 As shown, the method includes:

[0040] Step 1: Add persulfate to the coking wastewater concentrate to carry out the first step reaction and obtain the primary treatment solution.

[0041] In this embodiment of the invention, the coking wastewater concentrate mainly refers to the membrane concentrate produced by membrane filtration of coking wastewater. The coking wastewater membrane concentrate has a high concentration of pollutants, resulting in high color and high salt content, making it a difficult-to-treat industrial wastewater.

[0042] The ratio of the amount of persulfate added to the COD of the coking wastewater concentrate is 0.1-0.5:1, and the reaction time of the persulfate and the coking wastewater concentrate is 10-40 min. In this embodiment of the invention, the persulfate can be sodium persulfate, potassium persulfate, etc.

[0043] For example, the ratio of the amount of persulfate added to the COD of the coking wastewater concentrate is 0.1-0.5:1;

[0044] The ratio of the amount of persulfate added to the COD of the coking wastewater concentrate is 0.2:1;

[0045] The ratio of the amount of persulfate added to the COD of the coking wastewater concentrate is 0.3:1;

[0046] The ratio of the amount of persulfate added to the COD of the coking wastewater concentrate is 0.4:1;

[0047] The ratio of the amount of persulfate added to the COD of the coking wastewater concentrate is 0.5:1.

[0048] Specifically, hypochlorous acid and singlet oxygen are obtained by reacting persulfate with chloride ions in the coking wastewater concentrate. The coking wastewater concentrate is then decolorized using the color removal effects of hypochlorous acid and singlet oxygen. The primary treated liquid obtained in the first step contains sulfate, hypochlorite, and chloride ions.

[0049] Step 2: Transfer the primary treatment solution to an irradiation device for irradiation treatment to obtain a secondary treatment solution.

[0050] The irradiation treatment involves irradiating the primary treatment liquid with an electron beam. The electron beam irradiation is achieved through an electron accelerator. The irradiation dose of the electron beam irradiation is determined according to actual needs. In order to reduce energy consumption, the irradiation dose of the electron beam irradiation is set between 1 and 4 kGy in this embodiment of the invention.

[0051] Specifically, electron beam irradiation converts oxygen in the air and wastewater into ozone. The generated ozone has a good selective removal effect on wastewater, and air is widely available. Compared to directly introducing ozone, the device that generates ozone during irradiation and then uses it to remove color from wastewater is simple and easy to implement. Therefore, after the first reaction is completed and the primary treatment liquid is transferred to the irradiation device for further treatment, the ozone generated during irradiation is collected and introduced into the secondary treatment liquid. Simultaneously, since the primary treatment liquid also contains sulfate, hypochlorite, and chloride ions, hypochlorite and chloride ions can be converted into hypochlorite free radicals during electron beam irradiation, synergistically with ozone for color removal and enhancing the removal effect. Therefore, electron beam irradiation can simultaneously generate ozone and hypochlorite free radicals for wastewater decolorization, which is more effective and less costly than using ozone alone.

[0052] Step 3: Collect the ozone generated in the irradiation device and the secondary treatment liquid respectively, and introduce the ozone into the secondary treatment liquid and add ferrous salt to carry out the final reaction, so as to reduce the color of the coking wastewater concentrate to less than 10 times.

[0053] During irradiation, oxygen in the air is oxidized into ozone. However, the ozone produced does not completely react with the primary treatment solution, leaving residual ozone in the irradiation unit. Therefore, when collecting the secondary treatment solution, this residual ozone can be collected and reintroduced into the secondary treatment solution for further reaction and color removal. This avoids wasting ozone generated by irradiation energy and further improves the color removal effect. It should be noted that during irradiation, the ozone generated in the treatment solution mainly reacts with pollutants in the solution. Therefore, the ozone concentration in the wastewater after treatment is negligible, and most of the remaining ozone is concentrated in the air within the irradiation unit. Thus, ozone collection can be achieved directly by collecting the air from the irradiation unit.

[0054] Specifically, during the irradiation process, air is introduced into the gas collection device from the irradiation unit to collect ozone during the reaction. After ozone collection, it is introduced into the secondary treatment liquid to further treat the liquid. Ozone collection can be completed by detecting the ozone concentration in the irradiation unit after irradiation, or by setting a specific time for ozone collection within a set period. This set time can be the time for the reaction to stand after irradiation, or a pre-set time to collect ozone at a higher concentration.

[0055] Simultaneously, ferrous salt is added to the secondary treatment solution. The added ferrous ions react with hypochlorous acid and irradiated hydrogen peroxide in the treatment solution to produce ferric ions. Utilizing the high selectivity of ferric ions, the color removal effect is enhanced. The added ferrous salt can be ferrous sulfate, ferrous chloride, etc. This invention primarily utilizes the properties of ferrous ions; therefore, the type of ferrous salt is not specifically limited. Since the concentration of hypochlorous acid in the solution mainly depends on the irradiation dose, the amount of ferrous ions added is determined according to the irradiation dose. Specifically, the amount of ferrous salt added is between 75-350 mg / L.

[0056] For example, the dosage of the ferrous salt is 75 mg / L;

[0057] The dosage of the ferrous salt is 150 mg / L;

[0058] The dosage of the ferrous salt is 300 mg / L.

[0059] In the embodiments of the present invention, the chloride ions used all originate from the wastewater itself. Therefore, the method for reducing the color of wastewater in the embodiments of the present invention is more suitable for the treatment of high-salinity wastewater, especially for wastewater with a chloride ion concentration of 1 g / L or higher.

[0060] Since the irradiation device is a dedicated irradiation reaction chamber, subsequent steps are quite complex. Therefore, the secondary treatment liquid obtained from the irradiation treatment is collected into another reaction device, such as a reaction pool commonly used in industry, to facilitate the introduction of ozone and the addition of treatment agents.

[0061] In some embodiments, to avoid excessive ferrous ions being added to the wastewater and affecting water quality, flocculants or adsorbents can be added after color removal to remove iron from the wastewater. Alternatively, sand filtration can be used to remove iron from the wastewater.

[0062] The method for reducing the color of coking wastewater concentrate provided in this invention involves sequentially treating the wastewater with persulfate, irradiation, ozone, and ferrous salt. Persulfate reacts with chloride ions in the water to generate hypochlorous acid and singlet oxygen, removing color. Then, electron beam irradiation generates ozone and hypochlorous acid radicals in the water, further removing color. Finally, ferrous salt is added, and ferrous ions react with hypochlorous acid and hydrogen peroxide generated during irradiation to generate high-valence iron, removing color again. Thus, through the synergistic effect of persulfate, electron beam irradiation, ozone, and high-valence iron, the reaction process... The method achieves better color removal, and the synergistic use of persulfate, electron beam irradiation, ozone, and ferric sulfate for color removal is more cost-effective than single irradiation or ozone treatment. Furthermore, since the ozone generated in the irradiation device is collected and reintroduced into the wastewater during the reaction, the utilization rate of active substances generated during irradiation is improved. In addition, due to the partial valence state change of chloride ions during the reaction, its inhibitory effect is reduced while promoting the formation of highly selective active species such as hypochlorous acid and ferric sulfate. Therefore, it has a better decolorization effect on coking wastewater concentrate.

[0063] In a second aspect, the present invention provides a system for reducing the color of coking wastewater concentrate, which is used to implement the method for reducing the color of coking wastewater concentrate described in the first aspect above, so as to solve the problems of poor decolorization effect and color return when using advanced oxidation methods to remove color from coking wastewater.

[0064] Reference Figure 2 , Figure 2 This diagram illustrates a system for reducing the color of coking wastewater concentrate according to an embodiment of the present invention. Figure 2 As shown, it includes:

[0065] The system comprises a first reaction device 1, an irradiation device 2, a second reaction device 3, and a gas collection device 4;

[0066] The first reaction device 1 and the irradiation device 2, and the irradiation device 2 and the second reaction device 3 are connected in sequence through a liquid delivery pipeline;

[0067] The irradiation device is provided with an air inlet and an air outlet. The air outlet is connected to the gas collection device 4 via a gas delivery pipeline to the second reaction device 3.

[0068] Specifically, the concentrated coking wastewater is fed into the first reaction unit 1, and persulfate is added to carry out the first step of the reaction to obtain the primary treated liquid;

[0069] Then, the primary treatment liquid is transported to irradiation device 2 via a liquid transport pipeline for irradiation treatment. During the irradiation process, air is introduced through the air inlet 21 of the irradiation device. The oxygen in the air generates ozone under electron beam irradiation, which is used to remove the color of the coking wastewater concentrate. Simultaneously, since the ozone generated in the air during the irradiation process cannot completely react with the wastewater concentrate, there is usually residual ozone in irradiation device 2. To make full use of the ozone, the gas flowing out of the outlet of irradiation device 2 is collected by gas collection device 4. After collection, it is introduced into the secondary treatment liquid transported from the liquid transport pipeline to the second reaction device 3 for further color removal.

[0070] In some embodiments, since wastewater treatment is a continuous process, the secondary treatment liquid is treated in the second reaction device 3 while the irradiation device 2 is performing irradiation treatment. Therefore, the gas collection device 4 can be omitted, and the irradiation device 2 and the second reaction device 3 can be directly connected by a gas delivery pipeline. By continuously introducing air into the air inlet of the irradiation device 2, the gas inside the irradiation device 2 flows from the air outlet through the gas delivery pipeline to the second reaction device 3. Thus, the ozone generated in the irradiation device 2 is directly introduced into the secondary treatment liquid in the second reaction device 3.

[0071] The gas delivery pipe extends into the second reaction device 3, and the gas outlet of the gas delivery pipe is located near the bottom of the second reaction device 3. To ensure sufficient contact between ozone and the coking wastewater concentrate and improve the decolorization effect on the coking wastewater concentrate, the gas outlet of the gas delivery pipe is positioned near the bottom of the second reaction device 3, allowing ozone to escape from below the surface of the secondary treated liquid.

[0072] The system for reducing the color of coking wastewater concentrate provided in this invention uses persulfate, irradiation, ozone, and ferrous salt in a first reaction device 1, an irradiation device 2, and a second reaction device 3, respectively, for wastewater treatment. Persulfate reacts with chloride ions in the coking wastewater concentrate to generate hypochlorous acid and singlet oxygen, thus removing color. Then, electron beam irradiation generates ozone and hypochlorous acid radicals in the water, further removing color. Finally, ferrous salt is added, and ferrous ions react with hypochlorous acid and hydrogen peroxide generated during irradiation to generate high-valence iron, further removing color. Thus, the persulfate... The synergistic effect of acid salts, electron beam irradiation, ozone, and high-valent iron results in better color removal during the reaction process. Simultaneously, the ozone generated in the irradiation device 2 is collected by the gas collection device 4 and fed into the second reaction device 3 to continue reacting with the wastewater, improving the utilization rate of active substances generated during irradiation. Furthermore, due to the partial valence state change of chloride ions during the reaction, the inhibitory effect of chloride ions on active substances generated during irradiation is reduced, while promoting the formation of highly selective active species such as hypochlorous acid and high-valent iron, resulting in a better decolorization effect on coking wastewater concentrate.

[0073] To enable those skilled in the art to better understand the present invention, the following describes a method and system for reducing the color of coking wastewater concentrate through several specific embodiments.

[0074] Example 1

[0075] A 100 mL sample of concentrated coking wastewater from a coking plant was collected. The sample was tested and found to have a color of 300 times, a COD of 305 mg / L, and a chloride ion concentration of 1.7 g / L.

[0076] Step 1: Add 30 mg of persulfate to the coking wastewater concentrate to carry out the first step reaction and obtain the primary treatment solution.

[0077] Step 2: Transfer the primary treatment solution to an irradiation device and irradiate it with an irradiation dose of 1 kGy to obtain a secondary treatment solution.

[0078] Step 3: Collect the ozone and secondary treatment liquid generated in the irradiation device, and introduce the ozone into the secondary treatment liquid and add 10 mg of ferrous chloride to carry out the final reaction; the color of the treated coking wastewater concentrate was reduced by 10 times after testing.

[0079] Example 2

[0080] A 100 mL sample of concentrated coking wastewater from a coking plant was collected. The sample was tested and found to have a color of 300 times, a COD of 305 mg / L, and a chloride ion concentration of 1.7 g / L.

[0081] Step 1: Add 50 mg of persulfate to the coking wastewater to carry out the first step reaction and obtain the primary treatment solution.

[0082] Step 2: Transfer the primary treatment solution to an irradiation device and irradiate it with an irradiation dose of 2 kGy to obtain a secondary treatment solution.

[0083] Step 3: Collect the ozone and secondary treatment liquid generated in the irradiation device, and introduce the ozone into the secondary treatment liquid and add 20mg of ferrous chloride to carry out the final reaction; the color of the treated coking wastewater concentrate was reduced by 8 times after testing.

[0084] Example 3

[0085] A 100 mL sample of concentrated coking wastewater from a coking plant was collected. The sample was tested and found to have a color of 300 times, a COD of 305 mg / L, and a chloride ion concentration of 1.7 g / L.

[0086] Step 1: Add 100 mg of persulfate to the coking wastewater to carry out the first step reaction and obtain the primary treatment solution.

[0087] Step 2: The primary treatment solution is transferred to an irradiation device and irradiated with an irradiation dose of 4 kGy to obtain a secondary treatment solution.

[0088] Step 3: Collect the ozone and secondary treatment liquid generated in the irradiation device, and introduce the ozone into the secondary treatment liquid and add 30mg of ferrous chloride to carry out the final reaction; the color of the treated coking wastewater concentrate was reduced by 2 times after testing.

[0089] Example 4

[0090] 100 mL of concentrated coking wastewater from a coking plant was taken. The test results showed that the color of the concentrated coking wastewater was 360 times, the COD was 287 mg / L, and the chloride ion concentration was 2.4 g / L.

[0091] Step 1: Add 50 mg of persulfate to the coking wastewater to carry out the first step reaction and obtain the primary treatment solution.

[0092] Step 2: Transfer the primary treatment solution to an irradiation device and irradiate it with an irradiation dose of 2 kGy to obtain a secondary treatment solution.

[0093] Step 3: Collect the ozone and secondary treatment liquid generated in the irradiation device, and introduce the ozone into the secondary treatment liquid and add 30mg of ferrous chloride to carry out the final reaction; the treated wastewater was tested and the color was reduced by 8 times.

[0094] Example 5

[0095] 100 mL of concentrated coking wastewater from a coking plant was taken. The test results showed that the color of the concentrated coking wastewater was 360 times, the COD was 287 mg / L, and the chloride ion concentration was 2.4 g / L.

[0096] Step 1: Add 50 mg of persulfate to the coking wastewater to carry out the first step reaction and obtain the primary treatment solution.

[0097] Step 2: The primary treatment solution is transferred to an irradiation device and irradiated with an irradiation dose of 4 kGy to obtain a secondary treatment solution.

[0098] Step 3: Collect the ozone and secondary treatment liquid generated in the irradiation device, and introduce the ozone into the secondary treatment liquid and add 30mg of ferrous chloride to carry out the final reaction; the color of the treated coking wastewater concentrate was reduced by 4 times after testing.

[0099] The method for reducing the color of coking wastewater concentrate using the embodiments of the present invention, due to the synergistic effect of multiple active species, significantly reduces the dosage of reagents compared to the method of adding ozone alone, resulting in shorter treatment time and lower cost. Therefore, the method for reducing the color of coking wastewater concentrate provided by the embodiments of the present invention offers higher economic benefits.

[0100] As can be seen from the above embodiments, the method for reducing the color of coking wastewater concentrate adopted in this invention removes color by adding hypochlorous acid and singlet oxygen obtained from the oxidation of persulfate to high-salt wastewater. Then, electron beam irradiation is used to oxidize the oxygen into ozone, which, along with the hypochlorous acid radicals generated during the irradiation process, removes color. Subsequently, the ozone generated during the irradiation process is collected and reintroduced into the wastewater after the reaction. Ferrous ions are added to the wastewater, and the ozone and ferric iron work synergistically to remove color. Thus, by employing a staged, multi-active method... The synergistic effect of species enhances the decolorization effect on wastewater. Furthermore, since the decolorization process primarily utilizes chloride ions already present in the wastewater, the required reagent dosage is not high. Additionally, during irradiation, the generated ozone is collected and reacted with the wastewater again, improving the utilization rate of the decolorizing reagent and resulting in better decolorization. Using the method provided in this embodiment for reducing the color of coking wastewater concentrate, the original color of wastewater exceeding 300 times can be reduced to 10 times or less, demonstrating excellent decolorization performance.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0102] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0103] The above provides a detailed description of a method and system for reducing the color of coking wastewater concentrate provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for reducing the color of coking wastewater concentrate, characterized in that, The method includes: Step 1: Add persulfate to the coking wastewater concentrate to carry out the first step reaction and obtain the primary treatment solution; Step 2: Transfer the primary treatment solution to an irradiation device for irradiation treatment to obtain a secondary treatment solution; Step 3: Collect the ozone generated in the irradiation device and the secondary treatment liquid respectively, and introduce the ozone into the secondary treatment liquid and add ferrous salt to carry out the final reaction so that the color of the coking wastewater concentrate is reduced to less than 10 times. In step 1, the ratio of the amount of persulfate added to the COD in the coking wastewater concentrate is 0.1-0.5:1, and the reaction time of the first step reaction is 10-40 min. In step 3, the dosage of the ferrous salt is 75-350 mg / L; The concentration of chloride ions in the coking wastewater concentrate is greater than or equal to 1 g / L.

2. The method for reducing the color of coking wastewater concentrate according to claim 1, characterized in that, In step 3, after the final reaction, the method further includes: Flocculants or activated carbon are added to the concentrated coking wastewater to remove iron from the wastewater.

3. The method for reducing the color of coking wastewater concentrate according to claim 1, characterized in that, In step 2, the irradiation dose of the irradiation treatment is 1-4 kGy.

4. The method for reducing the color of coking wastewater concentrate according to claim 1, characterized in that, The ferrous salt is either ferrous sulfate or ferrous chloride.

5. The method for reducing the color of coking wastewater concentrate according to claim 1, characterized in that, The irradiation treatment is electron beam irradiation, which is performed using an electron accelerator.

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