A wastewater fractional gradient arsenic removal device and method of use thereof

Abstract

The application provides a wastewater grading gradient arsenic removal device and a use method thereof, and belongs to the technical field of wastewater arsenic removal. The application solves the problem of unstable wastewater arsenic removal efficiency in the prior art. In the application, an iron salt feeding tank is connected with a premixing reaction device, a wastewater storage tank is connected with the premixing reaction device, the premixing reaction device is sequentially connected with a first-stage arsenic removal device and a second-stage arsenic removal device, the second-stage arsenic removal device is connected with the iron salt feeding tank, and the second-stage arsenic removal device is connected with an arsenic-removed liquid storage tank. The application comprises the following steps: adding iron salt and fresh water into an iron salt preparation tank, and mixing and reacting arsenic-containing wastewater in the wastewater storage tank with the iron salt solution in the premixing reaction device; controlling the addition amount of the iron salt solution in the second-stage arsenic removal device to perform a second-stage reaction; and storing the clear liquid after the reaction into the arsenic-removed liquid storage tank. The application achieves the purpose of grading and gradient wastewater arsenic removal, ensures that the effluent is environmentally friendly and meets the standard, and solves the problem of unstable wastewater arsenic removal efficiency.

Description

Technical Field

[0001] This invention belongs to the field of wastewater arsenic removal technology, specifically relating to a wastewater graded gradient arsenic removal device and its usage method. Background Technology

[0002] The pyrometallurgical process for non-ferrous metals generates a large amount of acidic wastewater containing arsenic and heavy metals. This wastewater is typically treated using a "sulfidation + neutralization + advanced treatment" process. First, sulfidation removes heavy metal ions and most of the arsenic. Then, neutralization removes sulfuric acid from the wastewater. Finally, advanced treatment removes any remaining arsenic before the wastewater is discharged in compliance with standards. The advanced treatment stage, as the final step in arsenic removal, directly impacts the final compliance rate. Currently, the industry commonly uses ferric salt flocculation for arsenic removal. This involves adding ferric salts to a reaction tank and mixing them with the arsenic-containing wastewater under stirring to remove arsenic. However, this simple method suffers from problems such as uneven and unstable solution mixing and inaccurate adjustment of ferric salt dosage. Insufficient or excessive ferric salt dosage leads to significant fluctuations in arsenic removal efficiency, resulting in inconsistent compliance. Summary of the Invention

[0003] The purpose of this invention is to provide a wastewater graded gradient arsenic removal device and its usage method to solve the problem of unstable arsenic removal efficiency in existing technologies.

[0004] The technical solution of the present invention is: a wastewater graded gradient arsenic removal device, comprising an iron salt preparation tank, an iron salt addition tank, and a wastewater storage tank. The iron salt preparation tank is connected to the iron salt addition tank via a pipeline. The iron salt addition tank is connected to a premixing reaction device via a primary iron salt addition pipe. The wastewater storage tank is connected to the premixing reaction device via a wastewater pipe. The premixing reaction device is sequentially connected to a primary arsenic removal device and a secondary arsenic removal device. The secondary arsenic removal device is connected to the iron salt addition tank via a secondary iron salt addition pipe. The secondary arsenic removal device is connected to a storage tank for the arsenic-removed liquid.

[0005] Furthermore, the primary iron salt dosing pipe is equipped with a primary iron salt dosing valve and a primary iron salt flow meter, which are interlocked with each other; the secondary iron salt dosing pipe is equipped with a secondary iron salt dosing valve, a secondary iron salt flow meter, and a flow restrictor, and the secondary arsenic removal device is equipped with a pH meter, which is interlocked with the secondary iron salt flow meter and the pH meter.

[0006] Furthermore, the primary arsenic removal device is a rectangular sealed cavity, with a first internal baffle dividing it into a primary reaction tank and a primary settling tank, which are connected by the top of the first internal baffle; the secondary arsenic removal device is a rectangular sealed cavity, with a second internal baffle dividing it into a secondary reaction tank and a secondary settling tank, which are connected by the top of the second internal baffle, and a pH meter is installed on the secondary reaction tank.

[0007] Furthermore, both the primary and secondary settling tanks have conical bottoms, with the conical bottoms being higher around the edges and lower in the center. The primary and secondary settling tanks are respectively connected to the center of their bottoms via primary and secondary slag discharge pipes, which are connected to filter presses. The filter presses are connected to the wastewater storage tanks via pipelines.

[0008] Furthermore, wastewater regulating valves and wastewater flow meters are respectively installed on the wastewater pipes, and the wastewater regulating valves and wastewater flow meters are interlocked.

[0009] Furthermore, a first check valve and a second check valve are respectively installed on the wastewater pipe and the primary iron salt dosing pipe.

[0010] Furthermore, stirring devices are installed in the iron salt preparation tank, the iron salt addition tank, the primary reaction tank, and the secondary reaction tank.

[0011] A method for using a wastewater graded gradient arsenic removal device includes the following steps:

[0012] Step 1: Add a measured amount of iron salt and fresh water to the iron salt preparation tank for preparation. The prepared iron salt solution enters the iron salt addition tank. The amount of iron salt solution added to the premixing reaction device is controlled by the primary iron salt addition valve and the primary iron salt flow meter. The arsenic-containing wastewater in the wastewater storage tank is controlled by the wastewater regulating valve and the wastewater flow meter. It enters the premixing reaction device to mix and react with the prepared iron salt solution.

[0013] Step 2: Calculate the amount of iron salt to be added based on the wastewater flow rate and arsenic content in Step 1. Control the amount of iron salt solution added in the secondary arsenic removal device through the secondary iron salt dosing valve, secondary iron salt flow meter and pH meter to carry out the secondary reaction.

[0014] Step 3: The purified liquid that meets environmental protection standards after arsenic removal is temporarily stored in the arsenic removal liquid storage tank. The sediment generated in the primary and secondary sedimentation tanks is sent to the filter press for filtration. The filter residue is temporarily stored, and the filtrate is sent to the wastewater storage tank for recycling.

[0015] The beneficial effects of this invention are as follows: A certain amount of iron salt and fresh water are added to the iron salt preparation tank for preparation. The prepared iron salt solution enters the iron salt addition tank. The arsenic-containing wastewater in the wastewater storage tank enters the premixing reaction device through the wastewater pipe. The iron salt solution in the iron salt addition tank is transported to the premixing reaction device through the primary iron salt addition pipe. After the wastewater and iron salt solution in the premixing reaction device are fully mixed, they enter the primary arsenic removal device for primary arsenic removal reaction. The solution after the primary arsenic removal reaction enters the secondary arsenic removal device for secondary arsenic removal reaction. Finally, the clear liquid that meets the environmental protection standards after arsenic removal is temporarily stored in the arsenic removal liquid storage tank.

[0016] The amount of iron salt solution added can be controlled by the primary iron salt dosing valve and the primary iron salt flow meter. Since most of the arsenic in the wastewater is removed in the primary arsenic removal device, the amount of iron salt added in the secondary arsenic removal device is relatively small. The flow restrictor can play a role in the initial flow regulation. At the same time, through the combined action of the secondary iron salt dosing valve, the secondary iron salt flow meter and the pH meter, the iron salt addition in the secondary arsenic removal device can be precisely controlled to avoid resource waste.

[0017] Internal baffles separate the primary and secondary arsenic removal units, allowing the mixed solution to enter the primary reaction tank for primary arsenic removal. Most of the arsenic in the wastewater is converted into precipitates. After the reaction, the liquid enters the primary settling tank for solid-liquid separation. The clarified liquid enters the secondary reaction tank, where iron salt solution is further transported for secondary arsenic removal. The liquid then enters the secondary settling tank for solid-liquid separation. The clarified liquid that meets environmental standards is temporarily stored in the arsenic removal liquid storage tank. Most of the arsenic slag is generated in the primary settling tank, with only a small amount generated in the secondary settling tank. During operation, personnel focus on removing sludge and slag from the primary settling tank, reducing the frequency of operation.

[0018] The conical bottom of the settling tank ensures the flowability of materials, helps avoid sludge and blockage, and increases the efficiency of emptying. The conical bottom allows fluid to flow naturally to the bottom and be discharged quickly, which helps improve production efficiency. The conical bottom can reduce the amount of solid matter that accumulates at the bottom, thereby extending the service life and helping to reduce the risk of accidents.

[0019] The sediment at the bottom of the primary and secondary settling tanks is sent to a filter press for filtration. The filter residue is temporarily stored, and the filtrate enters the wastewater storage tank for further recycling. The wastewater regulating valve is interlocked with the wastewater flow meter to automatically control the wastewater flow.

[0020] The first check valve prevents iron salt in the primary iron salt dosing pipe from flowing back into the wastewater pipe through the premixing reaction device, and the second check valve prevents wastewater in the wastewater pipe from flowing back into the primary iron salt dosing pipe through the premixing reaction device, thus enhancing the safety and stability of the device's normal operation. The stirring device can make the wastewater and iron salt solution mix more thoroughly, improving work efficiency.

[0021] The device of this invention is simple to operate and reliable in operation. After the wastewater and iron salt solution are mixed by the premixing reaction device, they enter the primary arsenic removal device for reaction. Most of the iron salt reacts in the primary arsenic removal device, and a small amount of iron salt reacts in the secondary arsenic removal device. Through the interlocking settings of the flow meter, dosing valve and pH meter and the setting of the flow limiting plate, the iron salt solution dosing can be coarsely and finely adjusted, realizing the purpose of graded and gradient arsenic removal from wastewater, ensuring that the effluent meets environmental protection standards, and solving the problem of unstable arsenic removal efficiency in wastewater. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the device connection of the present invention;

[0023] Figure 2 This is a structural diagram of the primary arsenic removal device in this invention;

[0024] Figure 3 This is a structural diagram of the secondary arsenic removal device in this invention.

[0025] In the diagram: 1-Iron salt preparation tank; 2-Iron salt dosing tank; 3-Primary iron salt dosing pump; 4-Secondary iron salt dosing pump; 5-Primary reaction tank; 6-Primary settling tank; 7-Secondary reaction tank; 8-Secondary settling tank; 9-Filter press inlet pump; 10-Filter press; 11-Wastewater pipe; 12-Primary iron salt dosing pipe; 13-Secondary iron salt dosing pipe; 14-Primary slag discharge pipe; 15-Secondary slag discharge pipe; 16-Wastewater regulating valve; 17-Primary iron salt dosing valve; 18-First check valve; 19-Secondary check valve; 20-Secondary iron salt dosing valve ; 21-Flow limiting plate; 22-Wastewater flow meter; 23-First-stage iron salt flow meter; 24-Second-stage iron salt flow meter; 25-pH meter; 26-Storage tank of arsenic-removed liquid; 27-First-stage slag discharge valve; 28-Second-stage slag discharge valve; 29-Premixing reaction device; 30-First-stage arsenic removal device; 31-Second-stage arsenic removal device; 32-Wastewater storage tank; 33-Wastewater transfer pump; 34-First internal baffle; 35-Stirring device; 36-Second internal baffle; 37-First motor; 38-Second motor; 39-Third motor; 40-Fourth motor. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] like Figures 1-3As shown, a wastewater graded gradient arsenic removal device includes an iron salt preparation tank 1, an iron salt addition tank 2, and a wastewater storage tank 32. The iron salt preparation tank 1 is connected to the iron salt addition tank 2 via a pipeline. The iron salt addition tank 2 is connected to a premixing reaction device 29 via a primary iron salt addition pipe 12. The wastewater storage tank 32 is connected to the premixing reaction device 29 via a wastewater pipe 11. The premixing reaction device 29 is sequentially connected to a primary arsenic removal device 30 and a secondary arsenic removal device 31. The secondary arsenic removal device 31 is connected to the iron salt addition tank 2 via a secondary iron salt addition pipe 13. The secondary arsenic removal device 31 is connected to a post-arsenic removal liquid storage tank 26.

[0028] The primary iron salt dosing pipe 12 is equipped with a primary iron salt dosing valve 17 and a primary iron salt flow meter 23, which are interlocked with each other. The secondary iron salt dosing pipe 13 is equipped with a secondary iron salt dosing valve 20, a secondary iron salt flow meter 24, and a flow limiting plate 21. The secondary arsenic removal device 31 is equipped with a pH meter 25, which is interlocked with the secondary iron salt flow meter 24 and the pH meter 25.

[0029] The primary arsenic removal device 30 is a rectangular sealed cavity, which is divided into a primary reaction tank 5 and a primary settling tank 6 by a first internal baffle 34. The primary reaction tank 5 and the primary settling tank 6 are connected by the top of the first internal baffle 34. The secondary arsenic removal device 31 is a rectangular sealed cavity, which is divided into a secondary reaction tank 7 and a secondary settling tank 8 by a second internal baffle 36. The secondary reaction tank 7 and the secondary settling tank 8 are connected by the top of the second internal baffle 36. A pH meter 25 is installed on the secondary reaction tank 7.

[0030] Both the primary settling tank 6 and the secondary settling tank 8 have conical bottoms, with the conical bottoms being high around the edges and low in the center. The primary slag discharge pipe 14 and the secondary slag discharge pipe 15 are respectively connected to the center of the bottom of the primary settling tank 6 and the secondary settling tank 8. The primary slag discharge pipe 14 and the secondary slag discharge pipe 15 are respectively connected to the filter press 10. The filter press 10 is connected to the wastewater storage tank 32 through a pipeline.

[0031] Wastewater regulating valve 16 and wastewater flow meter 22 are respectively installed on wastewater pipe 11, and wastewater regulating valve 16 and wastewater flow meter 22 are interlocked.

[0032] The wastewater pipe 11 and the primary iron salt dosing pipe 12 are respectively equipped with a first check valve 18 and a second check valve 19.

[0033] Stirring devices 35 are respectively installed in the iron salt preparation tank 1, iron salt addition tank 2, primary reaction tank 5 and secondary reaction tank 7.

[0034] A primary iron salt dosing pump 3 and a secondary iron salt dosing pump 4 are respectively installed at the connection points between the iron salt dosing tank 1 and the primary iron salt dosing pipe 12 and the secondary iron salt dosing pipe 13; a filter press inlet pump 9 is respectively connected between the primary slag discharge pipe 14 and the secondary slag discharge pipe 15 and the filter press 10; a wastewater transfer pump 33 is installed at the connection point between the wastewater storage tank 32 and the wastewater pipe 11; a primary slag discharge valve 27 and a secondary slag discharge valve 28 are respectively installed on the primary slag discharge pipe 14 and the secondary slag discharge pipe 15; a wastewater regulating valve 16, a primary iron salt dosing valve 17, and a secondary iron salt dosing valve 18 are also installed. The dosing valve 20, the primary slag discharge valve 27, and the secondary slag discharge valve 28 are all automatic valves; the stirring device 35 in the primary reaction tank 5 is connected to the first motor 37; multiple scraper blades are provided on the conical bottom of the primary settling tank 6, and the scraper blades are connected to the second motor 38; the stirring device 35 in the secondary reaction tank 7 is connected to the third motor 39; multiple scraper blades are provided on the conical bottom of the secondary settling tank 8, and the scraper blades are connected to the fourth motor 40; the scraper blades on the conical bottom of the settling tank can further clean the sediment and sludge, improving work efficiency.

[0035] Example 1

[0036] A measured amount of iron salt and fresh water are added to the iron salt preparation tank 1 to prepare a 10% iron salt solution. The iron salt solution flows into the iron salt addition tank 2 by gravity. Arsenic-containing wastewater in the wastewater storage tank 32 is pumped to the wastewater pipe 11 by the wastewater pump 33. The flow rate of the wastewater is controlled by the wastewater regulating valve 16 and the wastewater flow meter 22, and it enters the premixing reaction device 29. The iron salt solution is pumped to the premixing reaction device 29 by the primary iron salt addition pump 3. The amount of iron salt solution added is controlled by the primary iron salt addition valve 17 and the primary iron salt flow meter 23. After the wastewater and iron salt solution are fully mixed in the premixing reaction device 29, they enter the primary reaction tank 5 for the primary arsenic removal reaction. Most of the arsenic in the wastewater is converted into precipitates. The effluent then enters the primary settling tank 6 for solid-liquid separation, and the clarified liquid enters the secondary reaction tank 7. The iron salt solution is transported to the secondary reaction tank 7 through the secondary iron salt dosing pump 4 to perform secondary arsenic removal on the clarified liquid after the primary reaction. After the secondary arsenic removal reaction, the small amount of residual arsenic in the wastewater is converted into precipitate. The effluent after the reaction enters the secondary settling tank 8 for solid-liquid separation. The clarified liquid meets the environmental protection standards and enters the arsenic removal liquid storage tank 26 for temporary storage. It is then sent to the water-using unit for reuse or external discharge as needed. The precipitate at the bottom of the primary settling tank 6 and the secondary settling tank 8 enters the filter press inlet pump 9 through the primary slag discharge pipe 14 and the secondary slag discharge pipe 15, respectively, and is sent to the filter press 10 for filtration. The filter residue is temporarily stored, and the filtrate enters the wastewater storage tank 32 for recycling.

[0037] Arsenic in the wastewater is removed in stages by a primary arsenic removal device 30 and a secondary arsenic removal device 31. Iron salts are added separately to the primary and secondary arsenic removal devices 30 and 31 to ensure a stable iron salt dosage. The iron salt dosage is calculated based on the wastewater flow rate and arsenic content, and is coarsely controlled by the primary iron salt dosing valve 17 and the primary iron salt flow meter 23 to maintain the calculated dosage. After the iron salt and wastewater are thoroughly mixed in the premixing reaction device 29, they enter the primary reaction tank 5 for the primary arsenic removal reaction, avoiding fluctuations in arsenic removal efficiency caused by uneven mixing. 90% of the arsenic in the wastewater is removed by the primary arsenic removal device 30. Internal removal: Since most of the arsenic in the wastewater is removed in the primary arsenic removal device 30, the amount of iron salt added in the secondary arsenic removal device 31 is relatively small. The flow limiting plate 21 can play a precise adjustment role. The amount of iron salt added in the secondary arsenic removal device 31 is calculated based on the flow rate and arsenic content of the effluent from the primary arsenic removal device 30. The secondary iron salt dosing valve 20, the flow limiting plate 21, the secondary iron salt flow meter 24, and the pH meter 25 work together to finely adjust and control the precise addition of iron salt in the secondary arsenic removal device 31. At the same time, when the pH meter 25 detects a value lower than 7, the secondary iron salt dosing valve 20 automatically reduces its size to avoid excessive iron salt addition. Iron salts undergo coarse and fine adjustments via a premixing reaction device 29 and a flow restrictor 21. Most of the iron salts react in the primary arsenic removal device 30, while a small amount reacts in the secondary arsenic removal device 31, achieving graded and gradient arsenic removal and ensuring that the effluent meets environmental standards. Simultaneously, most arsenic slag is generated in the primary settling tank 6, with only a small amount generated in the secondary settling tank 8. During operation, the focus is on sludge removal from the primary settling tank 6, reducing the frequency of operation. This device is simple to operate and reliable, solving the problem of unstable arsenic removal efficiency in wastewater and ensuring that the effluent consistently meets standards.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wastewater graded gradient arsenic removal device, characterized in that: The system includes an iron salt preparation tank (1), an iron salt addition tank (2), and a wastewater storage tank (32). The iron salt preparation tank (1) is connected to the iron salt addition tank (2) via a pipe. The iron salt addition tank (2) is connected to a premixing reaction device (29) via a primary iron salt addition pipe (12). The wastewater storage tank (32) is connected to the premixing reaction device (29) via a wastewater pipe (11). The premixing reaction device (29) is connected in sequence to a primary arsenic removal device (30) and a secondary arsenic removal device (31). The primary arsenic removal device (30) is a rectangular closed cavity with a first internal baffle (34) inside to divide the primary arsenic removal device (30) into a primary reaction. The primary reaction tank (5) and the primary settling tank (6) are connected by the top of the first internal baffle (34); the secondary arsenic removal device (31) is a rectangular closed cavity, which is divided into a secondary reaction tank (7) and a secondary settling tank (8) by a second internal baffle (36). The secondary reaction tank (7) and the secondary settling tank (8) are connected by the top of the second internal baffle (36). The secondary arsenic removal device (31) is connected to the iron salt addition tank (2) through the secondary iron salt addition pipe (13). The secondary arsenic removal device (31) is connected to the arsenic removal liquid storage tank (26). The primary iron salt dosing pipe (12) is equipped with a primary iron salt dosing valve (17) and a primary iron salt flow meter (23), and the primary iron salt flow meter (23) and the primary iron salt dosing valve (17) are interlocked. The secondary iron salt dosing pipe (13) is equipped with a secondary iron salt dosing valve (20), a secondary iron salt flow meter (24) and a flow limiting plate (21), and the secondary arsenic removal device (31) is equipped with a pH meter (25), which is installed on the secondary reaction tank (7). The secondary iron salt dosing valve (20) is interlocked with the secondary iron salt flow meter (24) and the pH meter (25).

2. A wastewater graded gradient arsenic removal device according to claim 1, characterized in that: Both the primary settling tank (6) and the secondary settling tank (8) have conical bottoms, with the conical bottoms being high around the edges and low in the center. The primary settling tank (6) and the secondary settling tank (8) are respectively connected to the center of the bottom of the primary settling tank (6) and the secondary settling tank (8) via primary slag discharge pipe (14) and secondary slag discharge pipe (15). The primary slag discharge pipe (14) and the secondary slag discharge pipe (15) are respectively connected to a filter press (10). The filter press (10) is connected to the wastewater storage tank (32) via a pipeline.

3. A wastewater graded gradient arsenic removal device according to claim 1 or 2, characterized in that: Wastewater regulating valve (16) and wastewater flow meter (22) are respectively installed on the wastewater pipe (11), and the wastewater regulating valve (16) and wastewater flow meter (22) are interlocked.

4. The wastewater graded gradient arsenic removal device according to claim 3, characterized in that: The wastewater pipe (11) and the primary iron salt dosing pipe (12) are respectively equipped with a first check valve (18) and a second check valve (19).

5. The wastewater graded gradient arsenic removal device according to claim 4, characterized in that: The iron salt preparation tank (1), iron salt addition tank (2), primary reaction tank (5) and secondary reaction tank (7) are respectively equipped with stirring devices (35).

6. The method of using the wastewater graded gradient arsenic removal device according to claim 1 includes the following steps: Step 1: Add a certain amount of iron salt and fresh water to the iron salt preparation tank (1) for preparation. The prepared iron salt solution enters the iron salt addition tank (2). The amount of iron salt solution added to the premixing reaction device (29) is controlled by the first-stage iron salt addition valve (17) and the first-stage iron salt flow meter (23). The arsenic-containing wastewater in the wastewater storage tank (32) is controlled by the wastewater regulating valve (16) and the wastewater flow meter (22) and enters the premixing reaction device (29) to mix and react with the prepared iron salt solution. Step 2: Calculate the amount of iron salt to be added based on the flow rate and arsenic content of the wastewater in Step 1. Control the amount of iron salt solution added in the secondary arsenic removal device (31) through the secondary iron salt dosing valve (20), the secondary iron salt flow meter (24) and the pH meter (25) to carry out the secondary reaction. Step 3: The clear liquid that meets the environmental protection standards after arsenic removal is temporarily stored in the arsenic removal liquid storage tank (26). The sediment generated in the primary settling tank (6) and the secondary settling tank (8) is sent to the filter press (10) for filter pressing. The filter residue is temporarily stored, and the filtrate is sent to the wastewater storage tank (32) for recycling.

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