Two-stage oxidation device for sintering desulfurization and denitrification wastewater treatment

Abstract

The utility model belongs to the technical field of wastewater treatment, and relates to a two-stage oxidation device for sintering desulfurization and denitrification wastewater treatment. The device comprises a primary ozone treatment module, a secondary ozone treatment module, an ozone generator and an activating and dosing device. The process flow comprises two stages of primary ozone process treatment and secondary ozone process treatment. The wastewater directly reacts and indirectly reacts with ozone in sequence in the treatment process, organic waste in the wastewater is effectively and fully catalyzed and decomposed, and finally up-to-standard discharge is achieved. The device and equipment provided by the utility model are simple, do not need a complex treatment process, are easy to maintain, and are relatively low in maintenance medicament cost. The device provided by the utility model has continuity, can realize continuous water production, and does not generate secondary chemical pollution.

Description

Technical Field

[0001] The present application belongs to the technical field of wastewater treatment and relates to a two-stage oxidation device for treating sintering desulfurization and denitrification wastewater. Background Art

[0002] The desulfurization and denitrification wastewater generated in the steel sintering desulfurization and denitrification process is generally treated with pretreatment (removal of suspended solids, heavy metals, calcium) + steam stripping deamination and other processes, and thallium removal processes are configured as needed. Because the desulfurization and denitrification wastewater contains Class I pollutants such as arsenic, lead, and thallium, this treatment process meets the Class I pollutant emission standards and then flows into other water treatment systems for further treatment or dilution of other pollutants such as COD and total nitrogen.

[0003] Wastewater treated by this process still exhibits high salinity, high chloride, high sulfate, and high COD. Entering other water treatment systems will cause water quality fluctuations in these systems and impact their normal operation. Given the current demands for water conservation, emission reduction, and salt reduction and control, the entry of such high-salinity water into the wastewater reuse system has a significant impact on the water quality of the entire plant. In actual operation, membrane processes are often used to treat recycled water. Although the volume of this water is relatively small, it has a significant impact on the membrane process. Operational experience has proven that the recycled water treatment process is prone to scaling and membrane fouling, resulting in reduced treatment capacity, shortened membrane element life, and significantly impacting treatment stability. If this high-salinity water is diluted with other treated water and discharged, it may result in excessive discharge of pollutants such as COD and total nitrogen.

[0004] In summary, the amount of wastewater generated in the steel sintering desulfurization and denitrification process is small, and it has the characteristics of high COD and high total nitrogen content. The existing technology lacks a treatment device with high stability, high safety and low cost. Utility Model Content

[0005] In view of the current lack of an excellent treatment method for high-salt wastewater generated in the steel sintering desulfurization and denitrification process, the purpose of this application is to provide a two-stage oxidation device for treating sintering desulfurization and denitrification wastewater.

[0006] The wastewater generated in the above-mentioned steel sintering desulfurization and denitrification process has a small amount of water and a high salt content, and the value of desalination and reuse is not great. Therefore, the device provided in this application uses an ozone advanced oxidation process to directly treat the wastewater to meet the discharge standards without the need for mixing, dilution and discharge.

[0007] The device provided in this application is based on ozone advanced oxidation technology for wastewater treatment. Ozone advanced oxidation technology is mainly achieved through two pathways: direct reaction and indirect reaction. Among them, direct reaction refers to the direct reaction of ozone with organic matter in wastewater. This method has strong selectivity and generally attacks organic matter with double bonds. It is usually more effective for unsaturated aliphatic hydrocarbons and aromatic hydrocarbon compounds; indirect reaction refers to the decomposition of ozone to produce ·OH, which undergoes oxidation reaction with organic matter through ·OH. This method is not selective. Therefore, the device of this application involves multiple ozone catalytic tanks and contact oxidation tanks.

[0008] The purpose of this application can be achieved through the following technical solutions:

[0009] The technical solution of the present application provides a two-stage oxidation device for treating sintering desulfurization and denitrification wastewater, comprising a primary ozone treatment module, a secondary ozone treatment module, an ozone generator, and an activation dosing device; the primary ozone treatment module comprises a primary ozone catalytic tank, a primary contact oxidation tank, and a primary dissolved air flotation tank connected in sequence through a channel; the secondary ozone treatment module comprises a secondary ozone catalytic tank, a secondary contact oxidation tank, and a secondary dissolved air flotation tank connected in sequence through a channel;

[0010] The ozone generator is connected to the primary ozone catalytic tank and the secondary ozone catalytic tank respectively, and is used to generate ozone; the activation dosing device is connected to the primary contact oxidation tank and the secondary contact oxidation tank respectively, and is used to add an activator to the primary contact oxidation tank and the secondary contact oxidation tank respectively;

[0011] The primary dissolved air flotation tank is connected to the secondary ozone catalytic tank through a pipeline; the primary ozone catalytic tank in the primary ozone treatment module is connected to the water inlet, and the secondary dissolved air flotation tank in the secondary ozone treatment module is connected to the water outlet.

[0012] Furthermore, the primary ozone treatment module and the secondary ozone treatment module are two groups of devices with the same composition, which are used for multi-stage treatment of wastewater, and can improve the quality of the effluent.

[0013] Furthermore, the first-stage dissolved air flotation tank and the second-stage dissolved air flotation tank of the two-stage oxidation device are provided with exhaust ports; the first-stage dissolved air flotation tank and the second-stage dissolved air flotation tank are provided with a stirrer for stirring and flocculating the slag; the first-stage dissolved air flotation tank and the second-stage dissolved air flotation tank are provided with a discharge port connected to the slag sludge treatment tank for discharging the slag.

[0014] Furthermore, the ozone generator is preferably an air source plate-type ozone generator; the inlet of the ozone generator is connected to the air compression pipeline of the factory compressed air, and a ventilation valve is provided in the middle.

[0015] Furthermore, ozone aeration devices are provided on both sides of the ozone inlet of the first-stage ozone catalytic tank and the second-stage ozone catalytic tank, for decomposing ozone into tiny bubbles and fully mixing the bubbles with the wastewater.

[0016] Furthermore, the activation dosing device is equipped with an activator feed port for adding the activator; the activation dosing device is also equipped with a recycled water feed port for recycling the treated wastewater. The activation dosing device is used to prepare and add the activator, which is prepared in solid form and then added; the activator is a carbon-based composite material of composite activated silicon.

[0017] Furthermore, a water inlet pump is provided on the water inlet pipeline, a suction pump is provided on the pipeline between the first-level ozone catalytic tank and the first-level contact oxidation tank, a suction pump is provided on the pipeline between the first-level contact oxidation tank and the first-level dissolved air flotation tank, a suction pump is provided on the pipeline between the first-level dissolved air flotation tank and the second-level ozone catalytic tank, a suction pump is provided on the pipeline between the second-level ozone catalytic tank and the second-level contact oxidation tank, and a suction pump is provided on the pipeline between the second-level contact oxidation tank and the second-level dissolved air flotation tank.

[0018] Compared with the prior art, this application has at least the following advantages:

[0019] (1) The device of the present application utilizes the original process device without changing the treatment process of the pre-pollutants. Based on the ozone advanced oxidation technology, various indicators are achieved in the device to meet the emission standards without increasing the total amount of pollutants.

[0020] (2) Compared to other advanced oxidation devices, the two-stage oxidation device used in this application is continuous, does not increase the salt content in the water during the treatment process, and has a high efficiency in removing organic pollutants. Compared with traditional treatment methods, this device does not produce secondary chemical pollutant emissions, the potential secondary hazards are extremely small, the impact on the environment is reduced, and water can be produced continuously.

[0021] (3) The device provided by this application is relatively simple to operate and maintain, and the operating cost is reduced. Compared with traditional treatment methods, this device does not require the addition of other chemical agents, which reduces the difficulty of maintenance and operation. The cost of the required chemicals is low, which can save overall operating costs.

[0022] (4) This application adopts a two-stage ozone oxidation device for treatment, which has a stable treatment effect and can ensure 100% compliance with emission standards.

[0023] (5) This application utilizes a combination of two-stage ozone oxidation devices, which has the advantages of simple equipment and no need for complex processing procedures compared to other traditional devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is a schematic diagram of a two-stage oxidation device for treating sintering desulfurization and denitrification wastewater provided in this application;

[0025] Figure 2 A schematic diagram of an advanced oxidation treatment process for treating sintering desulfurization and denitrification wastewater provided in this application;

[0026] The marks in the figure indicate:

[0027] 1: ozone catalytic tank, 1-1: primary ozone catalytic tank, 1-2: secondary ozone catalytic tank;

[0028] 2: Ozone contact oxidation tank, 2-1: Secondary ozone contact oxidation tank, 2-2: Secondary ozone contact oxidation tank;

[0029] 3: Flotation tank, 3-1: first-level flotation tank, 3-2: second-level flotation tank;

[0030] 4: Activation dosing device, 5: Ozone generator, 6: Scum sludge treatment tank, 7: Main drain outlet;

[0031] I: Primary ozone process treatment, II: Secondary ozone process treatment. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solutions of the present application, the present application is described in detail below with reference to specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application. These all fall within the scope of protection of the present application.

[0033] All raw materials in this application are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0034] Example 1 A two-stage oxidation device for treating sintering desulfurization and denitrification wastewater

[0035] See also Figure 1 、 Figure 2It can be seen that the present application provides a two-stage oxidation device for treating sintering desulfurization and denitrification wastewater, comprising a primary ozone treatment module I, a secondary ozone treatment module II, a plate-type ozone generator 5, and an activation and dosing device 4. The primary ozone treatment module I comprises a primary ozone catalytic tank 1-1, a primary ozone contact oxidation tank 2-1, and a primary dissolved air flotation tank 3-1, connected in sequence; the secondary ozone treatment module II comprises a secondary ozone catalytic tank 1-2, a secondary ozone contact oxidation tank 2-2, and a secondary dissolved air flotation tank 3-1, connected in sequence. The primary ozone treatment module I and the secondary ozone treatment module II are two identical devices used to achieve multi-stage oxidation treatment of wastewater.

[0036] The ozone generator 5 is connected to the primary ozone catalytic tank 1-1 and the secondary ozone catalytic tank 1-2, respectively, and is used to generate ozone; the activation dosing device 4 is connected to the primary contact oxidation tank 2-1 and the secondary contact oxidation tank 2-2, respectively, and is used to add an activator to the primary contact oxidation tank 2-1 and the secondary contact oxidation tank 2-2, respectively; the primary dissolved air flotation tank 3-1 is connected to the secondary ozone catalytic tank 1-2 through a pipeline; the primary ozone catalytic tank 1-1 in the primary ozone treatment module I is connected to the water inlet, and the secondary dissolved air flotation tank 3-2 in the secondary ozone treatment module II is connected to the water outlet.

[0037] The primary and secondary dissolved air flotation tanks 3-1 and 3-2 of the two-stage oxidation unit are equipped with exhaust ports for discharging exhaust gases generated after catalysis. Agitators are installed in the primary and secondary dissolved air flotation tanks 3-1 and 3-2 for agitating and flocculating scum. Discharge ports are connected to the scum sludge treatment tank 7 for scum discharge.

[0038] The inlet of the ozone generator 5 is connected to the factory's compressed air pipeline, with a vent valve installed in the middle. The ozone generator is an air-sourced plate-type ozone generator. Ozone aeration devices are installed on both sides of the ozone inlet of the first-stage ozone catalyst tank 1-1 and the second-stage ozone catalyst tank 1-2 to decompose the ozone into tiny bubbles and thoroughly mix them with the wastewater. The activation dosing device 4 is equipped with an activator feed port for adding activator. The activation dosing device 4 is also equipped with a recycled water feed port for reuse after wastewater treatment.

[0039] A water inlet pump is provided on the water inlet pipeline, a suction pump is provided on the pipeline between the first-level ozone catalytic tank 1-1 and the first-level contact oxidation tank 2-1, a suction pump is provided on the pipeline between the first-level contact oxidation tank 2-1 and the first-level dissolved air flotation tank 3-1, a suction pump is provided on the pipeline between the first-level dissolved air flotation tank 3-1 and the second-level ozone catalytic tank 1-2, a suction pump is provided on the pipeline between the second-level ozone catalytic tank 1-2 and the second-level contact oxidation tank 2-2, and a suction pump is provided on the pipeline between the second-level contact oxidation tank 2-2 and the second-level dissolved air flotation tank 3-2.

[0040] Example 2 Process flow of a two-stage oxidation device for treating sintering desulfurization and denitrification wastewater

[0041] This embodiment provides a process flow carried out in the apparatus provided in Example 1, which adopts a two-stage ozone oxidation process and Shanghai Xiba's two-stage activated ozone technology, including the following steps:

[0042] S1. Primary ozone process treatment: Pump the sintering desulfurization and denitrification wastewater into the primary ozone treatment module and treat it for 0.5 to 1 hour to obtain wastewater treated with primary ozone.

[0043] First, the sintering desulfurization and denitrification wastewater is passed into the primary ozone catalytic tank of the primary ozone treatment module to fully mix the wastewater and ozone. At this stage, the ozone directly reacts with the organic matter in the wastewater; after the reaction, the wastewater is passed into the primary ozone contact oxidation tank. At this stage, under the action of the catalyst filler in the primary ozone contact oxidation tank, the ozone first decomposes to produce ·OH, and then ·OH reacts with the organic matter to further decompose the organic matter; after the oxidation reaction, the wastewater is passed into the primary flotation tank, and the small particles of scum / inorganic matter in the wastewater are captured and adsorbed by microbubbles. Finally, the scum is removed and enters the scum sludge treatment tank. The wastewater enters the secondary ozone treatment module for secondary ozone process treatment.

[0044] In this step, the flow rate / flow velocity of the sintering desulfurization and denitrification wastewater is 20-60m 3 / d; the pH of the sintering desulfurization and denitrification wastewater is 9-10; the conductivity is >20000μs / cm; the chloride ion concentration is 20000-30000mg / L; the COD is 800-1000mg / L; the ammonia nitrogen content is 30-40mg / L; the total nitrogen content is 80-90mg / L; and the total phosphorus content is 0.45-0.50mg / L.

[0045] Before the wastewater is mixed with ozone, an ozone aeration device is used to cut the ozone into tiny bubbles of 0.5 nanometers to ensure sufficient contact between the gas and liquid. The ozone then enters the primary ozone contact oxidation tank. Through direct reaction in the ozone catalytic tank and indirect reaction in the contact oxidation tank, the ozone's effectiveness is fully realized. Under the action of ozone oxidation, organic matter is broken down into inorganic matter and gas, which can be effectively removed by flotation.

[0046] The flotation tank is used to remove scum after catalysis / oxidation using a flotation method. Flotation utilizes highly dispersed microbubbles as carriers to adhere to pollutants in the wastewater, creating a buoyancy greater than gravity and upward resistance. This allows the pollutants to float to the surface, forming foam. This foam is then scraped off the surface using scraping equipment to achieve solid-liquid or liquid-liquid separation. The flotation process requires a large number of microbubbles to be distributed throughout the wastewater being treated, ensuring that the pollutants are suspended. Furthermore, the suspended particles must be hydrophobic, allowing them to easily adhere to the bubbles and float upward.

[0047] S2. Secondary ozone process treatment: The wastewater treated by the primary ozone treatment is pumped into the secondary ozone treatment module for treatment for 0.2 to 0.5 hours to obtain water that meets national standards for discharge.

[0048] The process flow in this step is the same as that of the primary ozone process treatment, that is, the operations in the two modules are the same, and the secondary ozone process treatment is a further treatment of the primary ozone treatment wastewater.

[0049] The wastewater treated by this process device / process can 100% meet the discharge standards; in order to save resources and reuse the effluent, the effluent is connected to an activation dosing device and the treated wastewater is used as a solvent for the activator.

[0050] Example 3 Treatment effect of wastewater from a steel desulfurization and denitrification process

[0051] In this embodiment, wastewater from a steel desulfurization and denitrification plant was treated using the apparatus and process flow provided in Examples 1 and 2. The treatment results are shown in Table 1, which shows that:

[0052] The COD concentration of the original wastewater was 890 mg / L. After two-stage ozone oxidation treatment, the COD concentration was reduced to 45 mg / L. The Iron and Steel Industry Water Pollutant Discharge Standard (GB 13456-2012) stipulates that the COD concentration of discharged wastewater should be 60 mg / L. After treatment with this device, the COD concentration was reduced to 45 mg / L, meeting the discharge standard.

[0053] In addition, other corresponding indicators also have high removal rates. For example, the concentration of ammonia nitrogen decreased from 34.5 mg / L to 8.32 mg / L, a decrease of 75.8%; the total nitrogen content decreased from 85.0 mg / L to 9.16 mg / L, a decrease of 89.2%; the Cl concentration decreased from 26996 mg / L to 7304 mg / L, a decrease of 72.9%.

[0054] In the two-stage ozone oxidation and flotation treatment process, as the pollutants are removed, the pH value and conductivity also show certain changes. The pH value increases due to the increase in alkalinity; the conductivity decreases significantly due to the effect of oxidation mineralization.

[0055] Table 1 Wastewater treatment effect of Example 3 of this application

[0056]

[0057] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, this application is not limited to the above-described embodiments. Any improvements and modifications made by those skilled in the art based on the disclosure of this application, without departing from the scope of this application, should be within the scope of protection of this application.

Claims

1. A two-stage oxidation device for treating sintering desulfurization and denitrification wastewater, characterized in that: It comprises a primary ozone treatment module (I), a secondary ozone treatment module (II), an ozone generator (5) and an activation and dosing device (4); The primary ozone treatment module (I) comprises a primary ozone catalytic tank (1-1), a primary contact oxidation tank (2-1), and a primary dissolved air flotation tank (3-1) connected in sequence through a channel; the secondary ozone treatment module (II) comprises a secondary ozone catalytic tank (1-2), a secondary contact oxidation tank (2-2), and a secondary dissolved air flotation tank (3-2) connected in sequence through a channel; The ozone generator (5) is connected to the primary ozone catalytic tank (1-1) and the secondary ozone catalytic tank (1-2) respectively, and the ozone generator (5) is used to generate ozone; the activation dosing device (4) is connected to the primary contact oxidation tank (2-1) and the secondary contact oxidation tank (2-2) respectively, and the activation dosing device (4) is used to add an activator to the primary contact oxidation tank (2-1) and the secondary contact oxidation tank (2-2) respectively; The primary dissolved air flotation tank (3-1) and the secondary ozone catalytic tank (1-2) are connected via a pipeline; the primary ozone catalytic tank (1-1) in the primary ozone treatment module (I) is connected to a water inlet, and the secondary dissolved air flotation tank (3-2) in the secondary ozone treatment module (II) is connected to a water outlet.

2. A two-stage oxidation device for treating sintering desulfurization and denitrification wastewater according to claim 1, characterized in that: The first-stage dissolved air flotation tank (3-1) and the second-stage dissolved air flotation tank (3-2) of the two-stage oxidation device are provided with exhaust ports.

3. A two-stage oxidation device for treating sintering desulfurization and denitrification wastewater according to claim 1, characterized in that: The first-stage dissolved air flotation tank (3-1) and the second-stage dissolved air flotation tank (3-2) are provided with a stirrer for stirring and flocculating the scum.

4. A two-stage oxidation device for treating sintering desulfurization and denitrification wastewater according to claim 1, characterized in that: The first-level dissolved air flotation tank (3-1) and the second-level dissolved air flotation tank (3-2) are provided with discharge ports connected to the scum sludge treatment tank (7) for discharging scum.

5. The two-stage oxidation device for treating sintering desulfurization and denitrification wastewater according to claim 1, characterized in that: The inlet of the ozone generator (5) is connected to the air compression pipeline of the factory compressed air, and a ventilation valve is arranged in the middle.

6. A two-stage oxidation device for treating sintering desulfurization and denitrification wastewater according to claim 1, characterized in that: The ozone generator is an air source plate type ozone generator.

7. The two-stage oxidation device for treating sintering desulfurization and denitrification wastewater according to claim 1, characterized in that: Ozone aeration devices are provided on both sides of the ozone inlet of the first-level ozone catalytic tank (1-1) and the second-level ozone catalytic tank (1-2), for decomposing ozone into tiny bubbles and fully mixing the bubbles with the wastewater.

8. The two-stage oxidation device for treating sintering desulfurization and denitrification wastewater according to claim 1, characterized in that: The activation and dosing device (4) is provided with an activator feed port for adding the activator.

9. The two-stage oxidation device for treating sintering desulfurization and denitrification wastewater according to claim 1, characterized in that: The activation and dosing device (4) is also provided with a recycled water feed port for recycling the treated wastewater.

10. The two-stage oxidation device for treating sintering desulfurization and denitrification wastewater according to claim 1, characterized in that: A water inlet pump is provided on the pipeline of the water inlet, a suction pump is provided on the pipeline between the first-level ozone catalytic tank (1-1) and the first-level contact oxidation tank (2-1), a suction pump is provided on the pipeline between the first-level contact oxidation tank (2-1) and the first-level dissolved air flotation tank (3-1), a suction pump is provided on the pipeline between the first-level dissolved air flotation tank (3-1) and the second-level ozone catalytic tank (1-2), a suction pump is provided on the pipeline between the second-level ozone catalytic tank (1-2) and the second-level contact oxidation tank (2-2), and a suction pump is provided on the pipeline between the second-level contact oxidation tank (2-2) and the second-level dissolved air flotation tank (3-2).

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