High-cyanogen coking wastewater pretreatment device

Abstract

The utility model provides a high-cyanogen coking wastewater pretreatment device. The high-cyanogen coking wastewater pretreatment device comprises a complexation reaction zone, an oxidation air flotation zone, a flocculation reaction zone, an inclined tube settling zone and an ozone catalytic dissolved air tank, the complexation reaction zone, the oxidation air flotation zone, the flocculation reaction zone and the inclined tube sedimentation zone are connected in sequence; and the ozone catalytic dissolved air tank is connected between the inclined tube settling zone and the oxidation air flotation zone. According to the utility model, the complex reaction zone, the oxidation air floatation zone, the flocculation reaction zone, the inclined tube settling zone and the ozone catalytic air dissolving tank are fully utilized to carry out chemical complex reaction, ozone catalytic oxidation, dissolved air floatation and chemical precipitation on the high-cyanogen coking wastewater, and the characteristics of all treatment processes are reasonably combined and mutually promoted, so that the total cyanogen in the high-cyanogen coking wastewater is efficiently reduced; meanwhile, the device has the effects of removing oil and suspended matters, provides guarantee for subsequent treatment units, can be constructed in an integrated manner, can be disassembled into unit combinations, and is high in field adaptability and high in operation efficiency.

Description

Technical Field

[0001] The utility model relates to the technical field of environmental protection, in particular to a pretreatment device for high-cyanide coking wastewater. Background Technique

[0002] Coking wastewater is the wastewater generated during the production of coke, gas, tar and coking products in a coking plant. Its composition is complex, containing a large number of refractory, highly toxic substances and carcinogens that are harmful to aquatic organisms and the human body. Especially the cyanide-containing wastewater has a strong inhibitory effect on the growth and reproduction of microorganisms, with poor biodegradability, making the biochemical treatment of coking wastewater very difficult.

[0003] When biological treatment methods such as activated sludge are used for coking wastewater, there is no perfect pretreatment cyanide removal device, resulting in problems such as low efficiency in the biochemical treatment section, poor shock resistance, unstable operation and high operation costs.

[0004] At present, the treatment methods for cyanide-containing wastewater mainly include chlorination method, ozone method, electrochemistry method and sulfur dioxide-air method, etc. These methods have their own advantages and disadvantages, and certain effects have been achieved in engineering according to the differences in usage conditions. However, these methods have certain limitations in the pretreatment of wastewater with high total cyanide. Especially for coking wastewater with high thiocyanate, it cannot meet the biochemical influent requirements. Therefore, there is an urgent need for a pretreatment device that can effectively reduce the cyanide in coking wastewater.

[0005] In view of this, the present utility model is specifically proposed. Content of the Utility Model

[0006] The purpose of the present utility model is to provide a pretreatment device for high-cyanide coking wastewater, which can enhance the conversion efficiency of thiocyanate and cyanide, reduce the impact of total cyanide on the biochemical system, is particularly applicable to the water quality characteristics of high-cyanide coking wastewater, and solves the problems of low pretreatment efficiency of high-cyanide coking wastewater and easy poisoning and collapse of the biochemical system.

[0007] The present utility model provides a pretreatment device for high-cyanide coking wastewater, including: a complexation reaction zone, an oxidation and flotation zone, a flocculation reaction zone, an inclined tube sedimentation zone and an ozone catalytic air dissolution tank; the complexation reaction zone, the oxidation and flotation zone, the flocculation reaction zone and the inclined tube sedimentation zone are connected in sequence; the ozone catalytic air dissolution tank is connected between the inclined tube sedimentation zone and the oxidation and flotation zone.

[0008] Preferably, the complexation reaction zone is provided with a stirrer and a dosing pipeline, and a complexing agent is added through the dosing pipeline. The complexing agent is preferably an iron ion salt and a ferrous ion salt. After the complexing agent is added, the iron ion salt and the ferrous ion salt complex thiocyanate and cyanide, and the dosing amount of the complexing agent is 1.1 times the theoretical value.

[0009] Preferably, a releaser is provided at the lower part of the oxidation air flotation zone, a slag scraper is provided at the upper part of the oxidation air flotation zone, and a tail gas destroyer is provided at the top of the oxidation air flotation zone.

[0010] Preferably, the ozone dosing concentration in the oxidation air flotation zone is 2-6 mg / L. At this concentration, the oxidation and air flotation reactions are carried out simultaneously to achieve the purpose of reducing free thiocyanate, cyanide and oil.

[0011] Preferably, the bottom of the ozone catalytic air dissolving tank is connected to the releaser through a pipeline, and the top of the ozone catalytic air dissolving tank is connected to the inclined tube sedimentation zone through a pipeline.

[0012] Preferably, a return water pipeline and a drainage pipeline are provided at the upper part of the inclined tube sedimentation zone. The return water pipeline is connected to the top of the ozone catalytic air dissolving tank; a return sludge pipeline and a sludge discharge pipeline are provided at the bottom of the inclined tube sedimentation zone. The return sludge pipeline is connected to the bottom of the flocculation reaction zone.

[0013] Preferably, the water return ratio of the return water pipeline is 10%-40% of the water inflow.

[0014] Preferably, the sludge return ratio of the return sludge pipeline is 2%-5% of the water inflow.

[0015] Preferably, the bottoms of the complexation reaction zone, the oxidation air flotation zone and the flocculation reaction zone are connected in sequence, and the flocculation reaction zone is connected to the inclined tube sedimentation zone through an adjustable weir.

[0016] Preferably, a partition wall is provided at the upper part of the flocculation reaction zone, and an adjustable weir is provided near the partition wall. The water outlet of the adjustable weir is connected to the inclined tube sedimentation zone.

[0017] Preferably, the flocculation reaction zone is provided with a stirrer with a draft tube and a chemical dosing pipeline. A flocculant is added through the chemical dosing pipeline for flocculation reaction, and the dosing concentration of the flocculant is 0.3-0.6 mg / L.

[0018] Preferably, a catalyst packing layer is placed in the ozone catalytic air dissolving tank. The ozone catalytic air dissolving tank is connected to an ozone delivery pipeline, and the bottom outlet of the ozone delivery pipeline is located below the catalyst packing layer.

[0019] Preferably, the pressure in the ozone catalytic air dissolving tank is 0.3-0.5 MPa. The ozone high-efficiency catalytic air dissolving tank contains catalyst packing with large particle size (preferably 1-2 cm). The ozone air dissolving and catalytic oxidation reactions are carried out by using the catalytic action of the large-particle-size catalyst.

[0020] Preferably, the ozone catalytic air dissolving tank adjusts the water inflow through a PID-controlled reflux pump to keep the liquid level in the ozone catalytic air dissolving tank stable.

[0021] Beneficial effects:

[0022] (1) This device conducts chemical complexation reaction, ozone catalytic oxidation, dissolved air flotation, and chemical precipitation on high-cyanide coking wastewater by making full use of the complexation reaction zone, oxidation air flotation zone, flocculation reaction zone, inclined tube sedimentation zone, and ozone catalytic dissolved air tank. It reasonably combines the characteristics of each treatment process, promotes each other, efficiently reduces the total cyanide in high-cyanide coking wastewater, improves the biodegradability of the wastewater, and at the same time has the effects of removing oil and suspended solids, providing guarantee for the subsequent treatment unit.

[0023] (2) In the oxidation air flotation zone of this device, ozone oxidation reaction generates oxygen, increasing the dissolved oxygen in the wastewater and reducing the air supply for biochemical pre-aeration. Moreover, after ozone oxidation, it enters the flocculation reaction zone for flocculation precipitation. Ozone pre-oxidation has a certain promoting effect on the flocculation effect.

[0024] (3) This device can be integratedly constructed or disassembled into unit combinations, has strong site adaptability, and can be used for the transformation of traditional processes.

[0025] (4) This device has high operating efficiency, high ozone utilization rate, high automation degree, and low operating cost, and is especially suitable for the pretreatment of high-cyanide coking wastewater. Description of the Drawings

[0026] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic structural diagram of the high-cyanide coking wastewater pretreatment device provided by the present invention.

[0028] Description of the reference numerals: 1. Complexation reaction zone; 2. Release device; 3. Oxidation air flotation zone; 4. Scraper; 5. Tail gas destroyer; 6. Flocculation reaction zone; 7. Stirrer; 8. Adjustable weir; 9. Inclined tube sedimentation zone; 10. Ozone catalytic dissolved air tank. Detailed Embodiments

[0029] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the described embodiments are some, rather than all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0030] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0031] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present utility model, "a plurality of" means two or more, unless otherwise specifically defined. In addition, the terms "installed", "connected", "connected to" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0032] Embodiment

[0033] As Figure 1 shown, this embodiment provides a pretreatment device for high-cyanide coking wastewater, including: a complexation reaction zone 1, an oxidation flotation zone 3, a flocculation reaction zone 6, an inclined tube sedimentation zone 9, and an ozone catalytic air dissolving tank 10; the complexation reaction zone 1, the oxidation flotation zone 3, the flocculation reaction zone 6, and the inclined tube sedimentation zone 9 are connected in sequence; the ozone catalytic air dissolving tank 10 is connected between the inclined tube sedimentation zone 9 and the oxidation flotation zone 3.

[0034] In this embodiment, the complexation reaction zone 1 is provided with a stirrer and a dosing pipeline. A complexing agent (ferric ion, ferrous ion) is added through the dosing pipeline. The cyanide-containing coking wastewater with high thiocyanate and cyanide reacts with ferric ion and ferrous ion in the complexation reaction zone 1 to generate ferrocyanide complex. The reaction equations are as follows:

[0035] Fe 3+ +3SCN - =Fe(SCN)3↓

[0036] Fe 3+ +6CN - =[Fe(CN)6] 3-

[0037] 3Fe 2+ +2[Fe(CN)6] 3- =Fe3[Fe(CN)6]2↓

[0038] In this embodiment, taking advantage of the characteristic that the pH of the original wastewater is 7.5 - 9, the pH in the complexation reaction zone 1 does not need to be adjusted, and the dosage of iron ions is controlled at 1.1 times the theoretical value.

[0039] The wastewater after the complexation reaction is in full contact with ozone microbubbles and hydroxyl radicals generated by ozone in the oxidation and air flotation zone 3 for oxidation, so that the refractory organic matter and the remaining total cyanide are further oxidized, improving the biodegradability of the wastewater. At the same time, it has an air flotation effect, reducing the content of oil and suspended solids in the water. In the oxidation and air flotation zone 3, ozone oxidation reaction generates oxygen, increasing the dissolved oxygen in the wastewater and reducing the air supply for biochemical pre-aeration. The iron cyanide complex generated by the complexation reaction is relatively stable and is not easily oxidized and decomposed by ozone. Some macromolecular organic matters in the wastewater pre-oxidized by ozone are oxidized and decomposed into small molecular organic matters, increasing the number of molecules, promoting the partial aggregation of organic matters, enhancing the adsorption and bridging effects of high molecular flocculants, and making the generated iron cyanide complex more easily flocculated and precipitated for removal.

[0040] In this embodiment, the oxidation and air flotation zone 3 is sealed, and the equipment in the sealed area is made of antioxidant materials such as 316L stainless steel and polytetrafluoroethylene. A releaser 2 is arranged at the lower part of the oxidation and air flotation zone 3, and the water outlet of the ozone catalytic air dissolution tank 10 enters the oxidation and air flotation zone 3 through a pipeline and is released through the releaser 2; a slag scraper 4 is arranged at the upper part of the oxidation and air flotation zone 3, and floating slag such as oil and suspended solids is discharged into the floating slag tank through the slag scraper 4 for treatment together with the sludge discharged from the inclined tube sedimentation zone 9; a tail gas destroyer 5 is arranged at the top of the oxidation and air flotation zone 3, and the ozone tail gas is treated by the tail gas destroyer 5 and discharged up to standard.

[0041] In this embodiment, a medicine adding pipeline is arranged in the flocculation reaction zone 6 for conveying the flocculant, and a stirrer 7 with a draft tube is also arranged in the flocculation reaction zone 6, which can enhance the flocculation effect and adapt to the operation with different water volumes.

[0042] In this embodiment, the flocculation reaction zone 6 is communicated with the middle part of the inclined tube sedimentation zone 9 through an adjustable weir 8. A partition wall is arranged at the upper part of the flocculation reaction zone 6, and the adjustable weir 8 is arranged near the partition wall. The water outlet of the adjustable weir 8 is connected to the middle part of the inclined tube sedimentation zone 9. The setting of the partition wall can avoid the influence of the stirrer 7 on the adjustable weir 8 when stirring the water body to adjust the liquid level.

[0043] In this embodiment, a return water pipeline and a drainage pipeline are arranged at the upper part of the inclined tube sedimentation area 9. The return water pipeline is connected to the top of the ozone catalytic dissolved air tank 10, and a variable-frequency return pump is arranged on the return water pipeline. The water inflow is adjusted by controlling the variable-frequency return pump through PID to keep the liquid level in the ozone catalytic dissolved air tank 10 stable, effectively ensuring a stable ozone flow rate and total dosing amount. 20% of the effluent is returned to the ozone catalytic dissolved air tank 10 for pressurized ozone catalytic oxidation, greatly improving the oxidation efficiency and further enhancing the pretreatment removal effect of total cyanide and organic matter. The remaining effluent flows into the subsequent treatment unit through the drainage pipeline.

[0044] In this embodiment, a sludge return pipeline and a sludge discharge pipeline are arranged at the bottom of the inclined tube sedimentation area 9. The sludge return pipeline is connected to the bottom of the flocculation reaction area 6, and a variable-frequency sludge return pump is arranged on the sludge return pipeline. 3% of the sludge is returned to the flocculation reaction area 6, which is beneficial to the recycling of the flocculant and promotes the formation of flocs in the flocculation reaction area 6. The remaining sludge enters the subsequent sludge treatment unit through the sludge discharge pipeline.

[0045] In this embodiment, the bottoms of the complexation reaction area 1, the oxidation flotation area 3, and the flocculation reaction area 6 are connected in sequence. There are various connection methods. For example: the complexation reaction area 1, the oxidation flotation area 3, and the flocculation reaction area 6 are of an integral tank structure, and each area is separated by a wall. There are water passing holes at the bottom of the wall; or, the complexation reaction area 1, the oxidation flotation area 3, and the flocculation reaction area 6 are separate tank structures, and the bottoms of each tank are connected by pipelines.

[0046] In this embodiment, the ozone catalytic dissolved air tank 10 is a cylindrical pressure vessel, the bottom of which is connected to the release device 2 through a pipeline, and the top of the ozone catalytic dissolved air tank 10 is connected to the inclined tube sedimentation area 9 through a pipeline.

[0047] In this embodiment, a catalyst packing layer is placed in the ozone catalytic dissolved air tank 10. The ozone catalytic dissolved air tank 10 is connected to an ozone delivery pipeline, and the bottom outlet of the ozone delivery pipeline is located below the catalyst packing layer. The ozone is distributed at the bottom, avoiding blockage and caking of the catalyst packing.

[0048] In this embodiment, a filter plate is arranged in the catalyst packing layer to protect the catalyst. The large-particle-size catalyst contained therein can accelerate the dissolved air and enhance the ozone oxidation effect, avoiding blockage by suspended solids.

[0049] The working process of the present utility model is as follows:

[0050] The highly cyanide-containing coking wastewater enters the complexation reaction zone 1, and ferric ion and ferrous ion salts are added. The dosing amount is controlled at 1.1 times the theoretical value, and the stirring reaction time is 15 - 20 min. Then it enters the oxidation and air flotation zone 3 from the bottom of the tank body. The recycled water dissolved with ozone is released through the releaser 2 at the bottom of the tank body and is fully mixed with the influent water. Oxidation and air flotation reactions are carried out simultaneously at an ozone concentration of 2 - 6 mg / L to further reduce free thiocyanate and cyanide. At the same time, oil and suspended solids are removed by air flotation. The floating slag is discharged into the floating slag tank through the slag scraper 4 for treatment together with the sludge. The tail gas is discharged after being treated by the tail gas destroyer 5. Then it enters the flocculation reaction zone 6 from the bottom of the tank body and is fully mixed with the recycled sludge and the polymer flocculant under the circulating stirring action of the stirrer 7 with a draft tube. The stirrer is adjustable in speed, and the stirring intensity is adjusted according to the situation. The dosing concentration of the flocculant is 0.3 - 0.6 mg / L. There is a partition wall between the effluent area of the flocculation reaction zone 6 and the top of the main reaction area, and an adjustable weir 8 is set. The liquid level is adjusted by adjusting the height of the weir so that the liquid level of the oxidation and air flotation zone 3 is always 5 - 30 mm lower than the top of the floating slag tank weir. Then the wastewater enters the middle part of the inclined tube sedimentation zone 9 through the pipeline of the adjustable weir 8. The sludge sinks to the bottom hopper, and the effluent water enters the top effluent weir trough. Most of the effluent water flows into the subsequent treatment unit. 10% - 40% of the effluent water with the controlled influent water volume is refluxed to the top water inlet of the ozone catalytic dissolved air tank 10 by a variable-frequency booster reflux pump. Ozone gas is introduced into the air inlet, and the pressure is controlled at 0.3 - 0.5 MPa. The gas-water ratio is about 1:3. The effluent water of the ozone catalytic dissolved air tank 10 enters the oxidation and air flotation zone 3 through the pipeline under pressure and is released through the releaser 2. The water volume of the variable-frequency booster pump is adjusted by using PID control so that the liquid level of the ozone catalytic dissolved air tank 10 is controlled at the 60% - 70% position. There are large-particle-size catalyst fillers and corresponding filter plates in the tank. The ozone gas is evenly distributed at the bottom of the fillers, playing a role in flushing the fillers. The pressure difference before and after the catalyst is monitored by a pressure gauge. When the pressure difference is greater than 0.1 MPa, the machine is stopped for manual cleaning. 2% - 5% of the sludge with the controlled influent water volume is refluxed to the central position at the bottom of the flocculation reaction zone 6 by a reflux pump, and the remaining cyanide-containing sludge is discharged externally.

[0051] In summary, thiocyanate and cyanide in the wastewater are complexed with ferric ions and ferrous ions, and then the ozone microbubbles are used for efficient catalytic oxidation to produce an air flotation effect. Then the cyanide-containing sludge is separated by flocculation and sedimentation. This device combines the process characteristics of complexation reaction, air flotation, ozone catalytic oxidation, and coagulation sedimentation to pre-treat the highly cyanide-containing coking wastewater, effectively reducing the concentrations of thiocyanate and cyanide in the wastewater. At the same time, it effectively removes petroleum substances and suspended solids in the wastewater, improves the biodegradability of the wastewater, and provides guarantee for the subsequent treatment unit. Moreover, this device has high operating efficiency, high ozone utilization rate, high automation degree, and low operating cost, and is especially suitable for the pretreatment of highly cyanide-containing coking wastewater. In addition, the device can be integratedly constructed or disassembled into unit combinations, has strong site adaptability, and can be used for the transformation of traditional processes.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-cyanide coking wastewater pretreatment device, characterized in that: include: A complex reaction zone (1), an oxidation flotation zone (3), a flocculation reaction zone (6), an inclined tube sedimentation zone (9) and an ozone catalytic dissolution tank (10); the complex reaction zone (1), the oxidation flotation zone (3), the flocculation reaction zone (6) and the inclined tube sedimentation zone (9) are connected in sequence; the ozone catalytic dissolution tank (10) is connected between the inclined tube sedimentation zone (9) and the oxidation flotation zone (3).

2. The high-cyanide coking wastewater pretreatment device according to claim 1, characterized in that: A releaser (2) is arranged at the lower part of the oxidation flotation zone (3), a scraper (4) is arranged at the upper part of the oxidation flotation zone (3), and a tail gas destroyer (5) is arranged at the top of the oxidation flotation zone (3).

3. The high-cyanide coking wastewater pretreatment device according to claim 2 is characterized in that: The bottom of the ozone catalytic dissolving tank (10) is connected to the releaser (2) through a pipeline, and the top of the ozone catalytic dissolving tank (10) is connected to the inclined tube sedimentation area (9) through a pipeline.

4. The high-cyanide coking wastewater pretreatment device according to claim 1 is characterized in that: A water return pipe and a drainage pipe are arranged at the top of the inclined tube sedimentation zone (9), and the water return pipe is connected to the top of the ozone catalytic dissolving tank (10); a mud return pipe and a mud drainage pipe are arranged at the bottom of the inclined tube sedimentation zone (9), and the mud return pipe is connected to the bottom of the flocculation reaction zone (6).

5. The high-cyanide coking wastewater pretreatment device according to claim 1 is characterized in that: The bottoms of the complexing reaction zone (1), the oxidation flotation zone (3) and the flocculation reaction zone (6) are connected in sequence, and the flocculation reaction zone (6) is connected to the inclined tube sedimentation zone (9) through an adjustable weir (8).

6. The high-cyanide coking wastewater pretreatment device according to claim 1 is characterized in that: A partition wall is arranged on the upper part of the flocculation reaction zone (6), and an adjustable weir (8) is arranged near the partition wall. The water outlet of the adjustable weir (8) is connected to the inclined tube sedimentation zone (9).

7. The high-cyanide coking wastewater pretreatment device according to claim 1 is characterized in that: The flocculation reaction zone (6) is provided with an agitator (7) with a flow guide tube and a drug addition pipeline.

8. The high-cyanide coking wastewater pretreatment device according to claim 1 is characterized in that: A catalyst packing layer is placed in the ozone catalytic dissolving tank (10), and the ozone catalytic dissolving tank (10) is connected to an ozone delivery pipeline, wherein the bottom outlet of the ozone delivery pipeline is located below the catalyst packing layer.

9. The high-cyanide coking wastewater pretreatment device according to claim 1 is characterized in that: The complexing reaction zone (1) is provided with a stirrer and a drug adding pipeline.

10. The high-cyanide coking wastewater pretreatment device according to claim 1, characterized in that: The ozone catalytic gas dissolving tank (10) adjusts the water inflow by controlling the reflux pump through PID to maintain a stable liquid level in the ozone catalytic gas dissolving tank (10).

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