System for treating low-concentration cyanide-containing wastewater by ultraviolet catalytic oxidation

Abstract

The system for treating low-concentration cyanide-containing wastewater by ultraviolet catalytic oxidation integrates a pretreatment unit, an ultraviolet catalytic oxidation unit, a water outlet unit and a control system from left to right in the container body, can automatically process low-concentration cyanide-containing wastewater through the control process of each unit, and discharge the supernatant meeting the standard through the water outlet pipe of the water outlet unit. The system has the advantages of integrating various devices, efficiently degrading cyanide-containing wastewater by ultraviolet catalytic oxidation, convenient transportation, quick use, low operation and maintenance cost, etc.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology in environmental protection, and in particular to a system for treating low-concentration cyanide-containing wastewater by ultraviolet catalytic oxidation. Background Technology

[0002] Low-concentration cyanide-containing wastewater is widely generated in industries such as electroplating, metallurgy, and chemicals. The cyanide it contains is highly toxic, and direct discharge will severely pollute aquatic environments, harming ecosystems and human health. Currently, the main methods for treating low-concentration cyanide-containing wastewater include chemical oxidation, biodegradation, and adsorption. However, chemical oxidation requires the addition of large amounts of oxidant, which can easily cause secondary pollution; biodegradation is sensitive to water quality fluctuations and has a long treatment cycle; and adsorption requires frequent replacement of the adsorbent after it becomes saturated, resulting in high operation and maintenance costs.

[0003] Ultraviolet catalytic oxidation technology has attracted much attention for the treatment of low-concentration pollutants due to its advantages such as strong oxidation capacity and no secondary pollution. The form of the catalyst directly affects the treatment efficiency and operation and maintenance difficulty. Compared with suspended catalysts, immobilized catalysts can avoid the problems of catalyst loss and recovery, and are more suitable for industrial applications. However, most existing ultraviolet catalytic oxidation treatment systems are fixed structures, which have problems such as large footprint, long construction period and poor flexibility, making it difficult to adapt to the emergency or temporary treatment needs of different sites.

[0004] To address the aforementioned issues, several publications have revealed CN215627352U, "A Cyanide-Containing Wastewater Treatment Processor." This design proposes a sequentially connected structure comprising a raw water tank, reaction tank, sedimentation tank, ultraviolet ozone reactor, and activated carbon reactor, along with a stirrer, ozone generator, and waste gas processor. It utilizes the addition of acidic and alkaline reagents and catalysts to the reaction tank, combined with ultraviolet ozone oxidation and activated carbon adsorption to treat cyanide-containing wastewater. This method can remove thiocyanate ions at low cost, ensuring that the total cyanide concentration meets standards. However, its multi-unit, separate, series design lacks an integrated, mobile support structure, making it unsuitable for temporary wastewater discharge sites or remote mines. The rapid deployment requirement in the area necessitates the addition of various reagents such as acidic, alkaline, sodium sulfite, and flocculants, and relies on ozone generators and activated carbon columns. This not only results in high reagent and equipment costs but also frequent activated carbon replacement due to saturation and high energy consumption for ozone generation. Furthermore, the lack of a fixed catalyst structure necessitates continuous addition via a catalyst inlet pipe, leading to cumbersome operation and maintenance processes and limited applicability. CN102101708A, "Method and Apparatus for Photoelectrochemical Treatment of Cyanide-Containing Wastewater," proposes adjusting the pH of cyanide-containing wastewater to above 10 and adding NaCl, followed by electrolytic treatment under ultraviolet irradiation, with the effluent then adjusted to the correct pH. 7-9 Achieve cyanide standards; the supporting equipment includes a reaction tank, anode and cathode plates arranged in series, and ultraviolet lamps installed between the plates. Through the synergistic action of electrochemical oxidation, photocatalytic oxidation, and other multiple actions, it achieves the simultaneous removal of cyanide, heavy metals, and organic matter. However, it adopts a fixed reaction tank structure and lacks an integrated mobile carrier design, making it unsuitable for the rapid deployment needs of temporary sewage discharge sites or remote mining areas. It requires adjusting the wastewater to strong alkalinity and then back to neutrality, resulting in a cumbersome acid-base adjustment process and high reagent consumption. In addition, the additional addition of NaCl can easily introduce chloride ions, causing secondary pollution. It relies on anode and cathode plate electrolysis, and the plates are prone to passivation, leading to poor stability and requiring frequent maintenance and replacement. Moreover, it is a scattered setup, resulting in high operation and maintenance costs and high operational complexity. CN204079677U "Gold Mine Cyanide Wastewater Treatment System" proposes to use a photocatalytic reaction tank, ozone oxidation tank, ultraviolet / ozone oxidation tank, and coagulation. The treatment system consists of multiple units, including a mixing tank and a sedimentation tank, and is equipped with a water pump, an ozone generator, and a fan. The photocatalytic reaction tank contains ultraviolet lamps, quartz glass sleeves, and coated filters. The tank walls and filter surfaces are coated with nano-TiO2 photocatalysts. The ozone-related tanks are equipped with an aeration system. Through photocatalysis, ozone oxidation, coagulation, and sedimentation, the system can treat cyanide-containing wastewater from gold mines. It has the advantages of good treatment effect and stable operation. However, it adopts a multi-unit, separate layout and lacks an integrated mobile support structure, making it unsuitable for temporary sewage discharge or emergency treatment needs in remote locations such as gold mines. It relies on ozone generators and coagulants, resulting in high energy consumption and high reagent costs for ozone preparation. It also requires supporting waste gas treatment equipment, making the system complex. The TiO2 photocatalyst is coated, which is prone to peeling off over long-term operation, leading to a decrease in catalytic efficiency. Furthermore, the replacement and maintenance of the coated filters are cumbersome and difficult to operate.

[0005] Therefore, it is of great significance to develop a system for treating low-concentration cyanide-containing wastewater by ultraviolet catalytic oxidation. Summary of the Invention

[0006] The objective of this invention is to overcome the shortcomings of the prior art and provide a system for treating low-concentration cyanide-containing wastewater by ultraviolet catalytic oxidation. This system can integrate various devices and efficiently degrade cyanide-containing wastewater by ultraviolet catalytic oxidation, while also being convenient to transport, quick to put into use, and low in operation and maintenance costs.

[0007] The objective of this invention is achieved through the following technical solution: The ultraviolet catalytic oxidation system for treating low-concentration cyanide-containing wastewater integrates a pretreatment unit, an ultraviolet catalytic oxidation unit, an effluent unit, and a control system, arranged sequentially from left to right within the container body. It can automatically treat low-concentration cyanide-containing wastewater through the control processes of each unit, and the qualified supernatant is discharged through the effluent pipe of the effluent unit.

[0008] Compared with the prior art, the innovative points, advantages or effects of this invention are as follows: (1) Integrated design: The pretreatment, catalytic oxidation, effluent treatment and control system are integrated into the container body. The structure is compact, the footprint is small, and the standard container specifications are adopted. It can be conveniently transported by road, rail and other means, and can be quickly deployed to different sites. It is suitable for emergency treatment or temporary treatment needs.

[0009] (2) High treatment efficiency: The supported immobilized catalyst packing is used, the catalyst load is stable and not easy to lose, and it is made into granular, honeycomb or flat packing, which increases the contact area with wastewater; with the reasonable arrangement of ultraviolet light source components, hydroxyl radicals can be generated efficiently, rapidly degrading cyanide-containing pollutants, and the treated wastewater can meet the discharge standards.

[0010] (3) Low operation and maintenance costs: The immobilized catalyst packing is fixed by a detachable bracket, which facilitates regular replacement and regeneration; the ultraviolet lamp tube is covered with a quartz sleeve to reduce pollution and damage and extend its service life; the control system realizes automated operation, eliminating the need for a large number of manual operators and reducing operation and maintenance costs.

[0011] (4) Strong applicability: The pretreatment unit can adjust the pH of the wastewater to a suitable range and is suitable for low-concentration cyanide-containing wastewater of different water qualities; by replacing different types of immobilized catalyst packing, the treatment effect on specific cyanide-containing wastewater can be further improved, and the application range is wide.

[0012] In summary, this invention features an integrated design, high processing efficiency, low operation and maintenance costs, and strong applicability. Attached Figure Description

[0013] Figure 1This is a schematic diagram of a system for treating low-concentration cyanide-containing wastewater using ultraviolet catalytic oxidation, based on the present invention.

[0014] Figure 2 This is a schematic diagram of the ultraviolet light source component structure of an ultraviolet catalytic oxidation system for treating low-concentration cyanide-containing wastewater according to the present invention.

[0015] The symbols in the attached diagram represent: 1. Container body 2. Pretreatment unit 21. Inlet pipe 22. Bar screen filter 23. Water quality conditioning tank 24. pH adjuster dosing port 25. Stirring device 3. Ultraviolet catalytic oxidation unit 3a. First ultraviolet catalytic oxidation reactor 3b. Second ultraviolet catalytic oxidation reactor 31. Inlet pump 32. Ultraviolet light source assembly 321. Ultraviolet lamp 322. Quartz sleeve 33. Immobilized catalyst packing layer 34. Detachable support 35. Baffle plate 4. Outlet unit 41. Sedimentation 42. Outlet pipe 5. Control system 51. Controller 52. pH sensor 53. Liquid level sensor 54. Flow sensor The present invention will now be described in further detail with reference to the accompanying drawings. Detailed Implementation

[0016] Implementation, for example Figures 1-2 As shown, the ultraviolet catalytic oxidation system for treating low-concentration cyanide-containing wastewater integrates the pretreatment unit 2, ultraviolet catalytic oxidation unit 3, effluent unit 4, and control system 5, arranged sequentially from left to right within the container body 1. It can automatically treat low-concentration cyanide-containing wastewater through the control process of each unit, and the qualified supernatant is discharged through the effluent pipe of effluent unit 4.

[0017] The process of the present invention can be further described as follows: The pretreatment unit 2 includes an inlet pipe 21, a bar filter 22, and a water quality adjustment tank 23 connected in sequence. The inlet pipe 21 extends to the outside of the container body 1. The bar filter 22 is used to remove suspended solids in the wastewater. The water quality adjustment tank 23 is equipped with a pH adjustment agent dosing port 24 and a stirring device 25 to adjust the pH of the wastewater to a suitable range for ultraviolet catalytic oxidation reaction.

[0018] The ultraviolet catalytic oxidation unit 3 includes multiple ultraviolet catalytic oxidation reactors 3a and 3b connected in series. The first ultraviolet catalytic oxidation reactor 3a is connected to the water quality conditioning tank 23 via an inlet pump. The ultraviolet catalytic oxidation reactors 3a and 3b are equipped with an ultraviolet light source assembly 32 and an immobilized catalyst packing layer 33. The immobilized catalyst packing layer 33 is a supported catalyst structure. The catalyst is loaded on a carrier and made into granular, honeycomb, or flat packing. The packing is fixed in the reactor by a detachable support to form a fixed bed structure.

[0019] The ultraviolet light source assembly 32 of the ultraviolet catalytic oxidation unit 3 includes a plurality of ultraviolet lamps 321, which are evenly arranged on both sides or around the immobilized catalyst filler layer 33, and a reasonable distance is reserved between the ultraviolet lamps 321 and the immobilized catalyst filler layer 33 to ensure light transmission efficiency.

[0020] The ultraviolet lamp tube 321 is a low-pressure mercury lamp or an LED ultraviolet lamp with a wavelength range of 254~365nm. The ultraviolet lamp tube 321 is covered with a quartz sleeve 322 to prevent wastewater from directly contacting the lamp tube and causing pollution and damage.

[0021] The carrier of the immobilized catalyst packing layer 33 is any one of ceramic, quartz sand, honeycomb ceramic, or foamed metal.

[0022] The catalyst in the immobilized catalyst packing layer 33 is a TiO2-based catalyst, and the surface of the TiO2 is modified by N and Fe element doping to improve the ultraviolet light response efficiency and cyanide degradation ability.

[0023] The ultraviolet catalytic oxidation reactors 3a and 3b are equipped with guide plates 35, which are arranged in an S-shape to extend the residence time of wastewater in the reactor and improve the catalytic oxidation effect.

[0024] The water outlet unit 4 includes a sedimentation tank 41 and an outlet pipe 42 connected in sequence. The sedimentation tank 41 is used to retain a small amount of detached catalyst particles, and the outlet pipe 42 extends to the outside of the container body 1 to discharge the treated supernatant that meets the standards.

[0025] The sedimentation tank 41 is equipped with a conical sludge collection hopper at the bottom, and the bottom of the sludge collection hopper is connected to a sludge discharge pipe, which extends to the outside of the container body 1 to facilitate the periodic discharge of settled catalyst particles and impurities.

[0026] The control system 5 includes a controller 51, a pH sensor 52, a liquid level sensor 53, and a flow sensor 54. The pH sensor 52 is located in the water quality conditioning tank 23. The liquid level sensor 53 is located in both the water quality conditioning tank 23 and the reactor of the ultraviolet catalytic oxidation unit 3. The flow sensor 54 is located on the outlet pipe of the inlet pump. The controller 51 is electrically connected to the inlet pump, the ultraviolet light source assembly 32, the stirring device 25, and each sensor 52-54 to realize the automated operation of the system.

[0027] The control system 5 includes a remote monitoring module, which is connected to the controller 51 and can remotely monitor and control the system's operating parameters, thereby improving the convenience of operation and maintenance.

[0028] The working process of this embodiment is as follows: Low-concentration cyanide-containing wastewater enters the bar screen filter 22 through the inlet pipe 21, and after removing suspended solids, it enters the water quality conditioning tank 23; the pH sensor 52 in the water quality conditioning tank 23 detects the pH value of the wastewater in real time, and the signal is transmitted to the controller 51. The controller 51 controls the pH adjusting agent dosing port 24 to add acid or alkali, and starts the stirring device 25 to adjust the pH of the wastewater to neutral; the adjusted wastewater is sent to the first ultraviolet catalytic oxidation reactor through the inlet pump 31. The flow sensor 54 at the outlet of the inlet pump 31 monitors the inlet flow rate and feeds it back to the controller 51. If the flow rate increases or the water concentration increases, the controller 51... The power of the ultraviolet light source components 32 in the two reactors is adjusted synchronously to increase the power, and vice versa, to achieve a balance between energy saving and compliance with treatment standards. In the first reactor, the wastewater flows through the immobilized catalyst packing layer 33 under the action of the S-shaped guide plate 35. The ultraviolet lamp tube 321 excites the catalyst to generate hydroxyl radicals, which initially degrade cyanide. The wastewater after primary treatment enters the second ultraviolet catalytic oxidation reactor for further degradation. The liquid level sensor 53 in the two reactors monitors the liquid level in real time to avoid overflow or idling. The wastewater after two stages of treatment enters the sedimentation tank 41 to retain a small amount of detached catalyst particles. The supernatant is discharged directly through the effluent pipe 42.

[0029] As described above, the present invention can be well implemented. The above embodiments are only the best implementations of the present invention, but the implementation of the present invention is not limited to the above embodiments. Other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are all included within the protection scope of the present invention.

Claims

1. A system for treating low-concentration cyanide-containing wastewater by ultraviolet catalytic oxidation, characterized in that... The pretreatment unit (2), ultraviolet catalytic oxidation unit (3), effluent unit (4) and control system (5) are integrated and arranged in the container body (1) from left to right. The low-concentration cyanide-containing wastewater can be automatically treated through the control process of each unit, and the qualified supernatant is discharged through the effluent pipe of the effluent unit (4).

2. The system according to claim 1, characterized in that: The pretreatment unit (2) includes an inlet pipe (21), a bar screen filter (22), and a water quality adjustment tank (23) connected in sequence. The inlet pipe (21) extends to the outside of the container body (1). The bar screen filter (22) is used to remove suspended solids in the wastewater. The water quality adjustment tank (23) is equipped with a pH adjustment agent dosing port (24) and a stirring device (25) to adjust the pH of the wastewater to a suitable range for ultraviolet catalytic oxidation reaction.

3. The system according to claim 1, characterized in that: The ultraviolet catalytic oxidation unit (3) includes multiple ultraviolet catalytic oxidation reactors (3a, 3b) connected in series. The first ultraviolet catalytic oxidation reactor (3a) is connected to the water quality conditioning tank (23) through a water inlet pump. The ultraviolet catalytic oxidation reactors (3a, 3b) are equipped with an ultraviolet light source assembly (32) and an immobilized catalyst packing layer (33). The immobilized catalyst packing layer (33) is a supported catalyst structure. The catalyst is loaded on a carrier and made into granular, honeycomb or flat packing. The packing is fixed in the reactor by a detachable support to form a fixed bed structure.

4. The system according to claim 1, characterized in that: The ultraviolet catalytic oxidation unit (3) ultraviolet light source assembly (32) includes several ultraviolet lamps (321). The ultraviolet lamps (321) are evenly arranged on both sides or around the immobilized catalyst filler layer (33), and a reasonable distance is reserved between the ultraviolet lamps (321) and the immobilized catalyst filler layer (33) to ensure light transmission efficiency.

5. The system according to claim 1, characterized in that: The ultraviolet lamp (321) is a low-pressure mercury lamp or an LED ultraviolet lamp with a wavelength range of 254~365nm. The ultraviolet lamp (321) is covered with a quartz sleeve (322) to prevent wastewater from directly contacting the lamp and causing pollution and damage.

6. The system according to claim 1, characterized in that: The carrier of the immobilized catalyst packing layer (33) is any one of ceramic, quartz sand, honeycomb ceramic, or foam metal.

7. The system according to claim 1, characterized in that: The catalyst in the immobilized catalyst packing layer (33) is a TiO2-based catalyst, and the surface of TiO2 is modified by N and Fe element doping to improve the ultraviolet light response efficiency and cyanide degradation ability.

8. The system according to claim 1, 3, 4, 5, or 7, characterized in that: The ultraviolet catalytic oxidation reactors (3a, 3b) are equipped with guide plates (35), which are arranged in an S-shape to prolong the residence time of wastewater in the reactor and improve the catalytic oxidation effect.

9. The system according to claim 1, characterized in that: The water outlet unit (4) includes a sedimentation tank (41) and an outlet pipe (42) connected in sequence. The sedimentation tank (41) is used to intercept a small amount of detached catalyst particles, and the outlet pipe (42) extends to the outside of the container body (1) to discharge the treated supernatant.

10. The system according to claim 1 or 9, characterized in that: The sedimentation tank (41) is equipped with a conical sludge collection hopper at the bottom, and the bottom of the sludge collection hopper is connected to a sludge discharge pipe. The sludge discharge pipe extends to the outside of the container body (1) to facilitate the periodic discharge of precipitated catalyst particles and impurities.

11. The system according to claim 1, characterized in that: The control system (5) includes a controller (51), a pH sensor (52), a liquid level sensor (53), and a flow sensor (54). The pH sensor (52) is located in the water quality conditioning tank (23). The liquid level sensor (53) is located in the water quality conditioning tank (23) and the reactor of the ultraviolet catalytic oxidation unit (3). The flow sensor (54) is located on the outlet pipe of the water inlet pump. The controller (51) is electrically connected to the water inlet pump, the ultraviolet light source assembly (32), the stirring device (25), and each sensor (52~54) to realize the automated operation of the system.

12. The system according to claim 1 or 11, characterized in that: The control system (5) includes a remote monitoring module, which is connected to the controller (51) and can remotely monitor and control the system operating parameters, thereby improving the convenience of operation and maintenance.

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