Integrated equipment for deeply treating perfluorooctanoic acid wastewater

Abstract

The utility model discloses integrated equipment for deeply treating perfluorooctanoic acid wastewater, and relates to the technical field of wastewater treatment. Ultraviolet light catalysis, electric flocculation and adsorption technologies are integrated, so that three-stage synergistic purification of the perfluorooctanoic acid wastewater is realized, and organic fluorine and generated inorganic fluorine ions can be synchronously removed and degraded. The equipment comprises an ultraviolet light catalytic reaction device, an electric flocculation device and an adsorption device, an inlet of the electric flocculation device is communicated with an outlet of the ultraviolet light catalytic reaction device, and an outlet of the electric flocculation device is communicated with an inlet of the adsorption device. The method is used for improving the performance of the perfluorooctanoic acid wastewater equipment.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to an integrated device for the deep treatment of perfluorooctanoic acid (PFOA) wastewater. Background Technology

[0002] Perfluorooctanoic acid (PFOA) is a new type of pollutant with environmental persistence, bioaccumulation, and toxicity. Due to the high-energy C–F bonds in its molecule, it exhibits extremely high chemical and thermal stability and is widely used in textiles, coatings, fire-fighting foams, and semiconductor manufacturing. PFOA is continuously released into the environment throughout its entire life cycle, and because it is difficult to undergo natural degradation, photodegradation, and biodegradation, it is widely detected in various environmental media and has attracted widespread global attention.

[0003] Current technologies for treating PFOA include adsorption, ion exchange, and membrane separation. However, these physical methods merely transfer PFOA from the aqueous phase to the solid phase, without changing the total amount, and are prone to causing secondary pollution. Photocatalytic advanced oxidation technology is a promising and effective method for degrading PFOA; however, the development of photocatalysis in PFOA control is slow, mainly due to a lack of reaction equipment that meets practical water treatment requirements, making it difficult to achieve high efficiency and long-term operation. Furthermore, research on PFOA control primarily focuses on defluorination, with insufficient attention paid to the secondary pollutants, inorganic fluoride ions, generated during defluorination.

[0004] Therefore, PFOA wastewater treatment often faces the coexistence of multiple pollutants, including organic and inorganic fluorides, making it difficult for a single technology to achieve deep removal of PFOA pollutants. Ultraviolet photocatalysis can effectively degrade PFOA pollutants, electrocoagulation excels in removing high concentrations of fluoride ions, while adsorption devices can further remove incompletely degraded PFOA pollutants and low-concentration fluoride ion residues. However, current processes are limited to the removal of single species and lack integrated treatment equipment that combines ultraviolet photocatalysis, electrocoagulation, and adsorption technologies. Therefore, it is necessary to develop an integrated device capable of synergistically utilizing these multiple processes to achieve deep removal of PFOA wastewater. Summary of the Invention

[0005] The embodiments of this application provide an integrated device for the deep treatment of perfluorooctanoic acid (PFOA) wastewater, which integrates ultraviolet photocatalysis, electrocoagulation and adsorption technologies to achieve three-stage synergistic purification of PFOA wastewater, and can simultaneously remove organic fluoride and inorganic fluoride ions generated during degradation.

[0006] To achieve the above objectives, embodiments of this application provide an integrated device for the deep treatment of perfluorooctanoic acid (PFOA) wastewater, comprising an ultraviolet photocatalytic reaction device, an electrocoagulation device, and an adsorption device; the inlet of the electrocoagulation device is connected to the outlet of the ultraviolet photocatalytic reaction device, and the outlet of the electrocoagulation device is connected to the inlet of the adsorption device.

[0007] Furthermore, the ultraviolet photocatalytic reaction device includes a stainless steel reaction tube; an ultraviolet lamp is installed inside the stainless steel reaction tube; a quartz sleeve is installed outside the ultraviolet lamp; and a photocatalyst is installed between the quartz sleeve and the stainless steel reaction tube.

[0008] Furthermore, a filter screen is provided at the inlet of the stainless steel reaction tube.

[0009] Furthermore, the ultraviolet photocatalytic reaction device also includes a first storage tank; the inlet of the first storage tank is connected to the outlet of the stainless steel reaction tube, and the outlet of the first storage tank is connected to the electrocoagulation device; an electrochemical sensor is installed inside the first storage tank.

[0010] Furthermore, the first storage tank is also equipped with a circulation outlet; the circulation outlet is connected to the inlet of the stainless steel reaction tube.

[0011] Furthermore, the photocatalyst is supported on fused silica sand.

[0012] Furthermore, the electrocoagulation device includes an electrocoagulation reaction tank; an electrode plate is provided inside the electrocoagulation reaction tank; the electrode plate can generate Al after being energized. 3+ And aluminum hydroxy compounds.

[0013] Furthermore, a sludge discharge port is provided on the side wall of the electrocoagulation reaction tank.

[0014] Furthermore, the adsorption device includes a first granular activated carbon adsorption column, an activated carbon column loaded with layered metal hydroxide, and a second granular activated carbon adsorption column connected in series; the adsorbent in the activated carbon column loaded with layered metal hydroxide is a mixture of layered metal hydroxide and activated carbon, mixed at a mass ratio of 1:10.

[0015] Furthermore, pressure sensors are provided on the first granular activated carbon adsorption column, the activated carbon column loaded with layered metal hydroxide, and the second granular activated carbon adsorption column.

[0016] This application has the following advantages over the prior art:

[0017] 1. The integrated equipment for deep treatment of perfluorooctanoic acid (PFOA) wastewater in this application integrates ultraviolet photocatalysis, electrocoagulation and adsorption technologies in series. Through three-stage synergistic purification of PFOA wastewater, it achieves simultaneous removal of organic fluoride and inorganic fluoride generated during degradation.

[0018] 2. The integrated equipment for deep treatment of perfluorooctanoic acid wastewater in this application embodiment is equipped with an electrochemical sensor in the ultraviolet photocatalysis unit and a pressure sensor in the adsorption unit. It also integrates a PLC system, which can monitor the equipment's operating status in real time and realize full-process automation and intelligence.

[0019] 3. The integrated equipment for deep treatment of perfluorooctanoic acid (PFOA) wastewater in this application embodiment adopts a modular design. Different modules can be integrated yet remain relatively independent, and can also be freely combined according to actual water quality conditions, thus broadening the application range. Furthermore, the modular design allows for independent replacement of UV lamps, electrode plates, and adsorption filter elements, reducing maintenance costs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the integrated equipment for the deep treatment of perfluorooctanoic acid wastewater according to an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the ultraviolet photocatalytic reaction device in the integrated equipment for deep treatment of perfluorooctanoic acid wastewater according to an embodiment of this application. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0024] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0025] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation", "connection" and "joining" should be interpreted broadly, for example, they can refer to fixed connections, detachable connections, or integral connections; those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0026] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" can explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0027] Reference Figure 1 and Figure 2 The embodiments of this application provide an integrated device for the deep treatment of perfluorooctanoic acid wastewater, including an ultraviolet photocatalytic reaction device 1, an electrocoagulation device 2, and an adsorption device 3. The ultraviolet photocatalytic reaction device 1, the electrocoagulation device 2, and the adsorption device 3 are arranged sequentially along the flow direction of the wastewater and connected by pipelines.

[0028] The ultraviolet photocatalytic reaction device 1 is based on a flow-through ultraviolet reactor, in which molten quartz sand loaded with photocatalyst is filled into a stainless steel pipe. Specifically, the ultraviolet photocatalytic reaction device 1 includes a stainless steel reaction tube 101, a filter screen 102, an ultraviolet lamp tube 103, a quartz sleeve 104, a photocatalyst 105, and a first storage tank 106.

[0029] The stainless steel reaction tube 101 has an inlet and an outlet. An ultraviolet lamp 103, a quartz sleeve 104, and a photocatalyst 105 are all housed inside the stainless steel reaction tube 101. The ultraviolet lamp 103 is located at the center of the stainless steel reaction tube 101, and the quartz sleeve 104 is fitted over the ultraviolet lamp 103. The photocatalyst 105 is located between the quartz sleeve 104 and the stainless steel reaction tube 101. A filter screen 102 is located at the inlet of the stainless steel reaction tube 101. The photocatalyst 105 is loaded onto molten silica sand.

[0030] The first storage tank 106 is equipped with an inlet, an outlet, and a circulation outlet. The inlet of the first storage tank 106 is connected to the outlet of the stainless steel reaction tube 101 via a pipe, the outlet of the first storage tank 106 is connected to the electrocoagulation device 2, and the circulation outlet of the first storage tank 106 is connected to the inlet of the stainless steel reaction tube 101 via a pipe. An electrochemical sensor 107 is installed inside the first storage tank 106, which can monitor changes in PFOA concentration in real time.

[0031] The electrocoagulation device 2 includes an electrocoagulation reaction tank 201, an electrode plate 202, and a first storage tank 204. The side wall of the electrocoagulation reaction tank 201 is provided with an inlet, an outlet, and a sludge discharge port 203. The inlet of the electrocoagulation reaction tank 201 is connected to the outlet of the first storage tank 206 via a pipe. The outlet of the electrocoagulation reaction tank 201 is connected to the inlet of the first storage tank 204 via a pipe, and the outlet of the first storage tank 204 is connected to the adsorption device 3. The sludge discharge port 203 can periodically remove the sludge generated by the electrocoagulation reaction tank 201.

[0032] Electrode plates 202 are disposed within the electrocoagulation reaction tank 201. Multiple electrode plates 202 are made of aluminum. When energized, the electrode plates 202 generate Al. 3+ PFOA and aluminum hydroxide compounds react with fluoride ions in wastewater through adsorption, hydrogen bonding and complexation to form flocs, thereby removing the high concentration of fluoride ions degraded from PFOA.

[0033] The adsorption device 3 includes a first granular activated carbon adsorption column 301, an activated carbon column 302 loaded with layered metal hydroxide, a second granular activated carbon adsorption column 303, and a third storage tank 305 connected in series along the flow direction of the wastewater. The adsorbent in the activated carbon column 302 loaded with layered metal hydroxide is a mixture of layered metal hydroxide and activated carbon at a mass ratio of 1:10. The first granular activated carbon adsorption column 301, the activated carbon column 302 loaded with layered metal hydroxide, and the second granular activated carbon adsorption column 303 all have a detachable structure for easy replacement of the adsorbent. Pressure sensors 304 are installed at the top of each of the three activated carbon adsorption columns to monitor the pressure inside the adsorption column in real time.

[0034] Reference Figure 1 and Figure 2 The working principle of this application embodiment is as follows:

[0035] In operation, wastewater containing PFOA first enters the cavity of the stainless steel reaction tube 101 of the ultraviolet photocatalytic reaction device 1. Large particulate impurities in the wastewater are intercepted by the filter screen 102, preventing them from entering the reaction cavity and affecting the light utilization efficiency. Simultaneously, ultraviolet light emitted from the ultraviolet lamp 103 passes through the quartz sleeve 104 to excite the photocatalyst 105 to produce active species, degrading the PFOA in the wastewater. Because fused silica sand is used in the cavity, the light utilization efficiency is effectively guaranteed. Partially degraded wastewater is returned to the first storage tank 106 and then flows back into the cavity of the stainless steel reaction tube 101 until the PFOA degradation efficiency reaches over 90%. The electrochemical sensor 107 can monitor the PFOA concentration change in the storage tank in real time, thereby enabling monitoring of the degradation process.

[0036] Wastewater treated by ultraviolet photocatalytic reaction enters the electrocoagulation reaction tank 201 of the electrocoagulation device 2 through a pipeline. Inside the electrocoagulation reaction tank 201, the electrode plate 202 generates Al after being energized. 3+ Compounds such as aluminum hydroxyl are used to form flocs with fluoride ions in water through adsorption, hydrogen bonding, and complexation, thereby removing the high concentration of fluoride ions degraded by PFOA. The resulting sludge can be periodically removed through sludge discharge outlet 203.

[0037] The wastewater treated by electrocoagulation is stored in the second storage tank 204, and then enters the adsorption device 3 through pipelines. The adsorption device has three adsorption columns. First, it enters the first granular activated carbon adsorption column 301 to remove most of the long-chain organic fluorine compounds and residual flocs. Then, it enters the activated carbon column 302 loaded with layered metal hydroxides to adsorb and remove a small amount of short-chain organic fluorine compounds and most of the inorganic fluoride ions generated during degradation. Finally, it undergoes further purification in the second granular activated carbon adsorption column 303, achieving compliance with emission standards for PFOA pollutants and their degradation-generated inorganic fluoride ions. The treated water is then stored in the third storage tank 305. Simultaneously, pressure sensors 304 are installed at the upper end of the adsorption columns to monitor the pressure inside the columns at any time to prevent blockage.

[0038] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An integrated device for the deep treatment of perfluorooctanoic acid (PFOA) wastewater, characterized in that, It includes an ultraviolet photocatalytic reaction device, an electrocoagulation device, and an adsorption device; the inlet of the electrocoagulation device is connected to the outlet of the ultraviolet photocatalytic reaction device, and the outlet of the electrocoagulation device is connected to the inlet of the adsorption device.

2. The integrated equipment for deep treatment of perfluorooctanoic acid wastewater according to claim 1, characterized in that, The ultraviolet photocatalytic reaction device includes a stainless steel reaction tube; an ultraviolet lamp is installed inside the stainless steel reaction tube; a quartz sleeve is installed outside the ultraviolet lamp; and a photocatalyst is installed between the quartz sleeve and the stainless steel reaction tube.

3. The integrated equipment for deep treatment of perfluorooctanoic acid wastewater according to claim 2, characterized in that, A filter screen is installed at the inlet of the stainless steel reaction tube.

4. The integrated equipment for deep treatment of perfluorooctanoic acid wastewater according to claim 3, characterized in that, The ultraviolet photocatalytic reaction device also includes a first liquid storage tank; the inlet of the first liquid storage tank is connected to the outlet of the stainless steel reaction tube, and the outlet of the first liquid storage tank is connected to the electrocoagulation device; an electrochemical sensor is installed inside the first liquid storage tank.

5. The integrated equipment for deep treatment of perfluorooctanoic acid wastewater according to claim 4, characterized in that, The first storage tank is also equipped with a circulation outlet; the circulation outlet is connected to the inlet of the stainless steel reaction tube.

6. The integrated equipment for deep treatment of perfluorooctanoic acid wastewater according to claim 5, characterized in that, The photocatalyst is supported on fused silica sand.

7. The integrated equipment for deep treatment of perfluorooctanoic acid wastewater according to claim 6, characterized in that, The electrocoagulation device includes an electrocoagulation reaction tank; an electrode plate is provided inside the electrocoagulation reaction tank; the electrode plate can generate Al when energized. 3+ And aluminum hydroxy compounds.

8. The integrated equipment for deep treatment of perfluorooctanoic acid wastewater according to claim 7, characterized in that, The side wall of the electrocoagulation reaction tank is provided with a sludge discharge port.

9. The integrated equipment for deep treatment of perfluorooctanoic acid wastewater according to claim 8, characterized in that, The adsorption device includes a first granular activated carbon adsorption column, an activated carbon column loaded with layered metal hydroxide, and a second granular activated carbon adsorption column connected in series. The adsorbent in the activated carbon column loaded with layered metal hydroxide is a mixture of layered metal hydroxide and activated carbon, mixed at a mass ratio of 1:

10.

10. The integrated equipment for deep treatment of perfluorooctanoic acid wastewater according to claim 9, characterized in that, Pressure sensors are provided on the first granular activated carbon adsorption column, the activated carbon column loaded with layered metal hydroxide, and the second granular activated carbon adsorption column.

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