Multi-stage treatment tank for radioactive sewage of chemical plant

Abstract

The invention provides a multi-stage treatment tank for radioactive sewage of a chemical plant, which belongs to the technical field of sewage treatment and comprises a pre-sedimentation regulation tank, a first-stage chelation tank, a second-stage adsorption interception tank, a third-stage deep purification tank and a terminal detection tank which are communicated in sequence. The preliminary sedimentation tank is provided with a rotary mud scraping and pH adjusting assembly; an S-shaped baffling channel and a vortex stirrer are arranged in the primary tank, and a chelating agent is added; the secondary tank contains water distribution, a modified adsorption filter material and an ultrafiltration membrane; the third-stage tank is provided with an ion exchange resin column; the terminal pool is provided with online detection, and unqualified water automatically flows back. Through a multi-stage series connection process integrating automatic mud scraping and mixing, vortex enhanced chelation, gradient adsorption interception and modular ion exchange, and in cooperation with terminal online detection and intelligent backflow control, efficient deep purification of radioactive sewage of a chemical plant, full-process automatic operation and zero radiation exposure risk of operators are achieved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more specifically, to a multi-stage treatment tank for radioactive wastewater from a chemical plant. Background Technology

[0002] Currently, existing radioactive wastewater treatment technologies in chemical plants mostly employ single sedimentation, filtration, or ion exchange processes. These methods are ill-suited to the complex characteristics of wastewater, including diverse nuclides, fluctuating concentrations, and a large amount of suspended impurities. This results in low treatment efficiency, unstable effluent quality, and often requires multiple independent stages connected in series. This not only necessitates a large footprint and complex piping connections but also makes the wastewater highly susceptible to rapid clogging and poisoning of subsequent core adsorption materials or resins due to incomplete pretreatment. Furthermore, traditional treatment tanks rely heavily on mechanical stirring or static mixers for chemical mixing, leading to poor mixing uniformity, low reagent utilization, and a lack of effective automatic sludge removal mechanisms at the bottom of the tanks. This necessitates periodic manual dredging and maintenance in high-radiation areas, posing a significant radiation safety hazard.

[0003] Existing radioactive wastewater treatment systems generally lack intelligent closed-loop feedback control mechanisms. They typically employ timed and quantitative chemical dosing and fixed flow rate operation modes, failing to adjust process parameters in real time according to changes in influent water quality. This leads to frequent instances of chemical waste at low loads and substandard treatment at high loads. Furthermore, the lack of online real-time monitoring of end-effect water quality and automatic recirculation and retreatment of substandard water means that any exceedances in effluent are often only discovered after the fact, increasing the risk of illegal discharge of radioactive wastewater. This open-loop or semi-automatic operation mode not only increases the frequency of manual sampling and testing and the risk of radiation exposure but also fails to meet the stringent environmental and safety requirements for "zero discharge" of radioactive wastewater and fully unmanned intelligent control of the entire process.

[0004] Therefore, in view of the above situation, there is an urgent need to develop a multi-stage treatment tank for radioactive wastewater from chemical plants to overcome the shortcomings in current practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-stage treatment tank for radioactive wastewater from chemical plants, which aims to solve the problems mentioned in the background art.

[0006] The present invention is implemented as follows: a multi-stage treatment tank for radioactive wastewater from a chemical plant, comprising a tank assembly, wherein the tank assembly comprises a pre-sedimentation and conditioning tank, a primary chelation treatment tank, a secondary adsorption and interception tank, a tertiary deep purification tank, and a terminal detection tank that are connected in series along the wastewater flow direction, and adjacent tanks are connected by a tiered flow conveying assembly. The pre-sedimentation and conditioning tank is provided with a sedimentation plate on the upper inner side, a vertical partition plate on the lower side of the sedimentation plate, a rotating tube coaxially provided in the middle of the sedimentation plate, a scraper plate that cooperates with the inner wall of the sedimentation plate on the rotating tube, a motor that is connected to the rotating tube on the outer side of the tank assembly, one end of the rotating tube is connected to the water inlet pipe, and a pH adjustment and dosing component connected to the rotating tube is provided on the tank assembly. The primary chelation treatment tank is equipped with multiple sets of staggered baffles, which form a continuous S-shaped baffle channel. The uppermost baffle is equipped with a vortex stirring component on its water-facing surface. The tank assembly is equipped with a chelating agent dosing component that is connected to the upper part of the primary chelation treatment tank. The secondary adsorption and retention tank is provided with a water distribution assembly, a modified adsorption filter media layer, an ultrafiltration retention membrane assembly, and a support layer from bottom to top. The three-stage deep purification tank is equipped with a horizontal partition, and the partition is equipped with a modular ion exchange resin column assembly. The terminal detection pool is equipped with an online detection component. The lower part of the terminal detection pool is equipped with a qualified water discharge pipe and a non-qualified water return pipe, and the non-qualified water return pipe is connected to the water inlet pipe.

[0007] Optionally, the settling plate has an arc-shaped structure, including a filter screen and a baffle plate. The filter screen is located on the side closer to the primary chelation treatment tank, and the baffle plate is located on the side away from the primary chelation treatment tank. The upper end of the filter screen is fixed to the top of the pre-settling and regulating tank, and a sludge discharge gap is provided between the baffle plate and the side wall of the pre-settling and regulating tank. A vertical baffle is located on the lower side between the baffle plate and the filter screen. The side of the vertical baffle away from the primary chelation treatment tank forms a radioactive sludge temporary storage chamber. The tank assembly is provided with a sludge discharge port that communicates with the bottom of the radioactive sludge temporary storage chamber.

[0008] Optionally, the scraper blade is a hollow structure, the mixing chamber of the scraper blade is connected to the inner cavity of the rotating tube, and multiple water outlet holes connected to the mixing chamber are opened on the outer end of the scraper blade away from its rotation direction. Multiple rows of baffle blocks I and baffle blocks II are fixed in an alternating manner in the mixing chamber, and the unit blocks of baffle blocks I and baffle blocks II are evenly staggered. Multiple scraper blades are evenly distributed around the rotating tube.

[0009] Optionally, the pH adjustment dosing assembly includes a second storage tank, a second dosing pipe, and a second dosing pump. The second storage tank is fixed to the tank assembly. One end of the second dosing pipe is connected to the bottom of the second storage tank. The second dosing pump is installed on the second dosing pipe. The other end of the second dosing pipe is connected to a connecting ring. The connecting ring is rotatably sleeved on a rotating pipe. The rotating pipe has a connecting hole that communicates with the inner cavity of the connecting ring. The inlet pipe is rotatably connected to the rotating pipe and is fixed to the tank assembly through an inlet pipe bracket.

[0010] Optionally, the chelating agent dosing assembly includes a storage tank, an addition pipe, and an addition pump. The storage tank is fixed to the top of the tank assembly. One end of the addition pipe is connected to the bottom of the storage tank. The addition pump is installed on the addition pipe. The other end of the addition pipe is connected to the side of the upper end of the primary chelation treatment tank near the pre-sedimentation and conditioning tank. The storage tank contains a radionuclide chelating agent, which is one or a mixture of diethyldithiocarbamate, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, and diethylenetriaminepentaacetic acid.

[0011] Optionally, the vortex stirring assembly includes a mounting base, a linear telescopic cylinder, an arc-shaped telescopic cylinder, a drive shaft, a vortex impeller, and a second motor. The mounting base is located above the uppermost baffle plate. The cylinder body of the linear telescopic cylinder is fixed to the top of the tank assembly, and its telescopic spindle is hinged to the mounting base. The arc-shaped telescopic cylinder is located between the telescopic spindle of the linear telescopic cylinder and the mounting base. Multiple drive shafts are provided and evenly distributed on the side of the mounting base near the baffle plate. The vortex impeller is fixed to the end of the drive shaft away from the mounting base. A pulley is fixed on the inner side of the mounting base to the drive shaft. Adjacent pulleys are connected by a transmission belt. The second motor is fixed to the mounting base and is driven by one of the drive shafts. The rotation plane of the vortex impeller forms an angle of 45°-60° with the water flow direction of the S-shaped baffle channel.

[0012] Optionally, a cone-shaped guide platform is fixed at the bottom of the primary chelation treatment tank, and the end of the bottom of the primary chelation treatment tank near the pre-sedimentation and conditioning tank is connected to the upper part of the radioactive sludge temporary storage chamber through a sludge discharge pipe, and a sludge discharge pump is installed on the sludge discharge pipe.

[0013] Optionally, the water distribution component is connected to the aeration device, and the water distribution component has at least two layers of equal flow mesh plate structure, with the aeration end of the aeration device located between the two layers of equal flow mesh plate; the modified adsorption filter media layer consists of a zeolite filter media layer, a modified attapulgite filter media layer, and an iron-manganese oxide modified activated carbon filter media layer from bottom to top; the support layer is a graded pebble support layer, with a grid bracket fitted at the bottom of the support layer; the ultrafiltration interception membrane component includes a membrane support, multiple bundles of hollow fiber ultrafiltration membrane fibers, a water collection main pipe, and membrane connectors, with the hollow fiber ultrafiltration membrane fibers evenly arranged in a flat pattern on the membrane support, the inner cavity of the hollow fiber ultrafiltration membrane fibers connected to the water collection main pipe, and the water collection main pipe connected to the bottom of the secondary adsorption interception tank.

[0014] Optionally, the modular ion exchange resin column group adopts a combination of parallel and series arrangement structure, including at least two sets of resin column series units arranged in parallel. Each set of resin column series units includes at least three ion exchange resin columns connected in series in sequence. Each ion exchange resin column is equipped with an independent control valve at both the inlet and outlet ends. The ion exchange resin column is filled with selective ion exchange resin for radionuclides.

[0015] Optionally, the online detection component includes an online radionuclide detection component and an online pH detection component; the qualified water discharge pipe is equipped with an electric control valve, and the unqualified water return pipe is equipped with a return pump, both of which are electrically connected to the online radionuclide detection component and the online pH detection component.

[0016] The multi-stage treatment tank for radioactive wastewater from a chemical plant provided by this invention has the following beneficial effects: This invention constructs a four-stage deep purification closed-loop system consisting of chemical chelation, gradient adsorption, membrane interception, and ion exchange. Automatic sludge discharge and efficient reagent mixing are achieved through a rotating tube and a scraper. The vortex stirring component enhances the chelation reaction within the S-shaped flow channel. Combined with the stepped interception of the modified adsorption filter layer and the ultrafiltration membrane module, as well as the targeted removal capability of the modular resin column assembly, and relying on the online monitoring data of the terminal detection pool, the return pipe and discharge pipe are intelligently controlled. Ultimately, this achieves highly efficient deep removal of radionuclides, fully automated operation, and zero radiation exposure risk for operators.

[0017] In summary, this invention achieves highly efficient and deep purification of radioactive wastewater from chemical plants, fully automated operation, and zero radiation exposure risk for operators by integrating a multi-stage series process of automatic sludge scraping and mixing, eddy current enhanced chelation, gradient adsorption and interception, and modular ion exchange, combined with terminal online detection and intelligent reflux control.

[0018] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0020] Figure 1 This is a schematic diagram of the overall structure of a multi-stage treatment tank for radioactive wastewater from a chemical plant, provided in an embodiment of the present invention. Figure 2 for Figure 1 Another perspective structural diagram; Figure 3 for Figure 2 A magnified structural diagram of part A in the middle; Figure 4 An isometric view of a multi-stage treatment tank for radioactive wastewater in a chemical plant, provided in an embodiment of the present invention; Figure 5 This is a three-dimensional structural diagram of the sludge scraper section in a multi-stage treatment tank for radioactive wastewater in a chemical plant, provided in an embodiment of the present invention. Figure 6 for Figure 5A partial sectional view of the structure; Figure 7 This is a three-dimensional structural diagram of the vortex stirring component in the multi-stage treatment tank for radioactive wastewater in a chemical plant, provided in an embodiment of the present invention. Figure 8 for Figure 7 A partial cross-sectional structural diagram.

[0021] In the diagram: 1-Support leg, 2-Motor 1, 3-Tank assembly, 4-Compliant water discharge pipe, 5-Vortex stirring assembly, 6-Addition pump 1, 7-Storage tank 1, 8-Storage tank 2, 9-Return pump, 10-Unqualified water return pipe, 11-Sludge pump, 12-Sludge pipe, 13-Sludge outlet, 14-Inlet pipe support, 15-Inlet pipe, 16-Addition pump 2, 17-Addition pipe 2, 18-Connecting ring, 19-Rotating pipe, 20-Pre-sedimentation and conditioning tank, 21-Primary chelation treatment tank, 22-Secondary adsorption and interception tank, 23-Tertiary deep purification tank, 24-Terminal detection tank, 25-Vertical baffle 1, 26- 27-Sludge settling plate, 28-Reinforcing block, 29-Sludge scraper, 30-Addition pipe one, 31-Guide platform, 32-Baffle-type guide plate, 33-Water distribution assembly, 34-Modified adsorption filter media layer, 35-Ultrafiltration membrane assembly, 36-Support layer, 37-Baffle plate, 38-Modular ion exchange resin column assembly, 39-Stage flow pipe, 40-Stage flow pump, 41-Outlet, 42-Baffle one, 43-Baffle two, 44-Mixing chamber, 45-Drive shaft, 46-Vortex impeller, 47-Mounting base, 48-Arc-shaped telescopic cylinder, 49-Motor two, 50-Linear telescopic cylinder, 51-Transmission belt, 52-Pulley. Detailed Implementation

[0022] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention 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 invention.

[0024] The following is a detailed description, with reference to the accompanying drawings, of a multi-stage treatment tank for radioactive wastewater in a chemical plant according to an embodiment of the present invention.

[0025] like Figure 1-4 As shown, a multi-stage treatment tank for radioactive wastewater in a chemical plant is provided in one embodiment of the present invention. The tank assembly 3 includes a tank body assembly 3, and a support leg 1 is fixed at the bottom of the tank body assembly 3. The support leg 1 can support the device.

[0026] The pool assembly 3 includes a pre-sedimentation and conditioning pool 20, a primary chelation treatment pool 21, a secondary adsorption and interception pool 22, a tertiary deep purification pool 23, and a terminal detection pool 24, which are connected in series along the sewage flow direction. Adjacent pools are connected by a tiered flow conveying assembly.

[0027] A sedimentation plate 26 is fixedly installed on the upper inner side of the pre-sedimentation and conditioning tank 20. A vertical partition plate 25 is fixed on the lower side of the sedimentation plate 26. A rotating pipe 19 is coaxially arranged in the middle of the sedimentation plate 26. A scraper 28 that cooperates with the inner wall of the sedimentation plate 26 is installed and fixed on the rotating pipe 19. A motor 2 that is drivenly connected to one end of the rotating pipe 19 is installed and fixed on the outer side of the tank assembly 3. The other end of the rotating pipe 19 is connected to a water inlet pipe 15. A pH adjustment and dosing assembly connected to the rotating pipe 19 is also installed on the tank assembly 3. The scraper 28 is used to scrape off the sludge on the inner wall of the sedimentation plate 26 and mix the sewage and chemicals transported by the rotating pipe 19 and discharge them into the inner cavity of the sedimentation plate 26.

[0028] The primary chelation treatment tank 21 is equipped with multiple sets of staggered baffles 31 inside, which form a continuous S-shaped baffle channel in the tank. The uppermost baffle 31 has a vortex stirring component 5 on its water-facing surface. The tank assembly 3 is also equipped with a chelating agent dosing component that is connected to the upper part of the primary chelation treatment tank 21.

[0029] The interior of the secondary adsorption and retention tank 22 is provided with a water distribution assembly 32, a modified adsorption filter media layer 33, an ultrafiltration retention membrane assembly 34, and a support layer 35, arranged from bottom to top.

[0030] The three-stage deep purification tank 23 has a fixed transverse partition 36 inside, and a modular ion exchange resin column group 37 is installed on the transverse partition 36. The modular ion exchange resin column group 37 adopts a combination of parallel and series arrangement structure.

[0031] The terminal detection pool 24 is equipped with an online radionuclide detection component and an online pH detection component. The lower part of the terminal detection pool 24 is equipped with a qualified water discharge pipe 4 and an unqualified water return pipe 10, and the unqualified water return pipe 10 is connected to the water inlet pipe 15.

[0032] This invention integrates a pre-sedimentation and conditioning tank 20, a primary chelation treatment tank 21, a secondary adsorption and interception tank 22, a tertiary deep purification tank 23, and a terminal detection tank 24 into a multi-stage series deep purification process. The rotating tube 19 and the scraper 28 work together to achieve automatic sludge discharge and efficient mixing of pH reagents. The baffle plate 31 and the vortex stirring assembly 5 enhance the chelation reaction. Combined with the gradient interception effect of the modified adsorption filter layer 33 and the ultrafiltration interception membrane assembly 34, as well as the deep removal capability of the modular ion exchange resin column assembly 37, the invention achieves fully automated closed-loop treatment of radioactive wastewater from chemical plants, efficient removal of radionuclides, and zero risk of artificial radiation exposure through online monitoring and feedback control of the terminal detection tank 24.

[0033] like Figure 1-6 As shown, in one embodiment, the settling plate 26 adopts an arc-shaped structure. The settling plate 26 includes a filter screen plate on the side near the primary chelation treatment tank 21 and a baffle plate on the side away from the primary chelation treatment tank 21. The upper end of the filter screen plate is fixedly connected to the top of the pre-settling and regulating tank 20. The baffle plate is located between the end away from the filter screen plate and the side cavity wall of the pre-settling and regulating tank 20, forming a sludge discharge gap. The baffle plate is also fixedly connected to the side cavity wall of the pre-settling and regulating tank 20 by a reinforcing block 27, thereby improving the overall stability of the settling plate 26. The vertical baffle plate 25 is fixed on the lower side between the baffle plate and the filter screen plate. The space on the side of the vertical baffle plate 25 away from the primary chelation treatment tank 21 is a radioactive sludge temporary storage chamber. The tank assembly 3 is also provided with a sludge discharge port 13 that communicates with the bottom of the radioactive sludge temporary storage chamber.

[0034] Multiple scraper blades 28 are evenly distributed around the circumference. The scraper blades 28 have a hollow structure. The mixing chamber 43 of the scraper blade 28 is connected to the inner cavity of the rotating tube 19. Multiple water outlet holes 40 connected to the mixing chamber 43 are evenly distributed on the outer end of the scraper blade 28 away from its rotation direction. Multiple rows of baffle blocks 41 and baffle blocks 42 are fixed in an alternating manner in the mixing chamber 43. The unit blocks of baffle blocks 41 and baffle blocks 42 are evenly and alternately arranged, which is conducive to the uniform mixing of acid and alkali regulators and sewage. This increases the turbulence intensity of the mixing of acid and alkali regulators and sewage. The sewage is discharged through the specially arranged water outlet holes 40, avoiding sludge clogging the water outlet holes 40 and ensuring the sludge scraping reliability of the scraper blades 28.

[0035] For pH-adjustable dosing components, such as Figure 3As shown, the pH adjustment dosing assembly includes a second storage tank 8 fixed to the tank assembly 3. The second storage tank 8 is used to store acid-base regulators, such as dilute sulfuric acid, dilute hydrochloric acid, sodium hydroxide solution, calcium hydroxide suspension, or sodium carbonate solution, which can be selected as needed based on the acidity or alkalinity of the wastewater. A second addition pipe 17 is connected to the bottom of the second storage tank 8. An addition pump 16 is installed on the second addition pipe 17. The other end of the second addition pipe 17 is connected to a connecting ring 18, which is rotatably mounted on a rotating pipe 19. A connecting hole (not shown) is provided on the rotating pipe 19 inside the connecting ring 18. The second addition pipe 17 communicates with the inner cavity of the rotating pipe 19 through the connecting hole in the connecting ring 18 and the rotating pipe 19, ensuring that the rotation of the rotating pipe 19 is not affected during agent delivery.

[0036] The water inlet pipe 15 is rotatably connected to the rotating pipe 19, and the water inlet pipe 15 is also fixedly connected to the pool assembly 3 through the water inlet pipe bracket 14, which ensures the stability of the water inlet pipe 15.

[0037] In a preferred embodiment, the radius of curvature of the settling plate 26 is 0.8-1.2m; the aperture of the filter screen is 0.1-0.3mm, and it is made of 316L stainless steel; the width of the sludge discharge gap is 15-25mm to ensure that the radioactive sludge automatically slides down under gravity. This structure, through the coordinated design of the arc-shaped settling plate 26 and the sludge discharge gap, and by utilizing the clockwise rotation of the scraper plate 28 to scrape the sludge, achieves automatic collection and temporary storage of radioactive sludge, avoiding the radiation exposure risk caused by manual dredging.

[0038] For the pH adjustment dosing component, the selection is dynamically based on the initial pH value of the wastewater: when pH < 6.0, a 5% sodium hydroxide solution is used; when pH > 8.0, a 10% dilute sulfuric acid solution is used; and when the pH is in the range of 6.0-8.0, a 15% sodium carbonate solution is used. This selection strategy is based on the typical pH distribution of radioactive wastewater from chemical plants (measured data: 80% of the wastewater has a pH < 6.5 or > 7.5). This dosing system allows the pH adjustment accuracy to be controlled within ±0.2, reducing reagent waste and improving the heavy metal removal rate of the primary chelation treatment tank 21.

[0039] like Figure 1 , 4 As shown in Figures 7 and 8, in one embodiment, the chelating agent dosing assembly includes a storage tank 7 fixed to the top of the tank assembly 3. The bottom of the storage tank 7 is provided with an addition pipe 29, and an addition pump 6 is installed on the addition pipe 29. The lower end of the addition pipe 29 is connected to the upper end of the primary chelation treatment tank 21 near the pre-sedimentation and conditioning tank 20.

[0040] The storage tank 7 is used to store a radionuclide chelating agent. The radionuclide chelating agent is selected from one or more of diethyldithiocarbamate, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, and diethylenetriaminepentaacetic acid. It can rapidly chelate with radionuclides such as uranium, thorium, radium, strontium, and cesium in wastewater to form stable and insoluble chelated precipitates, thereby achieving efficient removal of radionuclides.

[0041] For the vortex stirring component 5, such as Figure 7 and 8 As shown, the vortex stirring assembly 5 is mounted on the upper side of the baffle plate 31 on the mounting base 46. A linear telescopic cylinder 49 is hinged to the upper side of the mounting base 46. The cylinder body of the linear telescopic cylinder 49 is fixed to the top of the tank assembly 3. An arc-shaped telescopic cylinder 47 is also fixed between the telescopic spindle of the linear telescopic cylinder 49 and the mounting base 46. The angle of the mounting base 46 relative to the linear telescopic cylinder 49 can be adjusted by the arc-shaped telescopic cylinder 47. Multiple drive shafts 44 are evenly distributed on the water-facing surface of the mounting base 46 near the uppermost baffle plate 31. A vortex impeller 45 is fixed to the end of the drive shaft 44 away from the mounting base 46. A pulley 51 is fixed on the inner side of the mounting base 46 to the drive shaft 44. Adjacent pulleys 51 are connected by a transmission belt 50. A motor 48 that is connected to one of the drive shafts 44 is also fixed on the mounting base 46. The rotation plane of the vortex impeller 45 forms an angle of 45°-60° with the water flow direction of the baffle channel, so that the rotation plane of the vortex impeller 45 and the water flow direction form the optimal turbulent shear zone.

[0042] Preferably, a conical guide platform 30 is fixed to the bottom of the primary chelation treatment tank 21. The bottom end of the primary chelation treatment tank 21, near the pre-sedimentation and conditioning tank 20, is also connected to the upper part of the radioactive sludge temporary storage chamber via a sludge discharge pipe 12, and a sludge discharge pump 11 is installed on the sludge discharge pipe 12. The guide platform 30 facilitates sludge deposition, and the sludge is transported to the radioactive sludge temporary storage chamber through the cooperation of the sludge discharge pump 11 and the sludge discharge pipe 12.

[0043] The vortex stirring assembly 5 has multiple operating modes: at low flow rates, the linear telescopic cylinder 49 drives the vortex impeller 45 to extend deeper below the liquid surface, while the arc-shaped telescopic cylinder 47 adjusts the angle between its rotation plane and the water flow direction to 60° to enhance local turbulence intensity and ensure thorough mixing of the reagents; at high flow rates, the impeller height is increased and the angle is reduced to 45° to reduce water flow resistance and maintain effective shear mixing.

[0044] In a preferred embodiment, the storage tank 7 is used to store radionuclide chelating agents. The dynamic concentration ratio of the chelating agent is 0.8-1.2% w / v, based on measured data of radionuclide distribution in wastewater (uranium content >45% and strontium content >30% in 80% of radioactive wastewater from chemical plants). The radionuclide chelating agent is selected from one or more mixtures of diethyldithiocarbamate (98.2% chelation rate for uranium), aminotrimethylenephosphonic acid (92.5% chelation rate for strontium), ethylenediaminetetramethylenephosphonic acid (89.7% chelation rate for cesium), and diethylenetriaminepentaacetic acid (94.3% chelation rate for radium). When the uranium content is >45%, diethyldithiocarbamate is the main component (70%), supplemented by aminotrimethylenephosphonic acid (30%). When the strontium content is >30%, the concentration is adjusted to aminotrimethylenephosphonic acid as the main component (60%), supplemented by ethylenediaminetetramethylenephosphonic acid (40%). This design improves the radionuclide removal rate of the primary chelation treatment pool 21 through a dynamic matching strategy of nuclide-chelating agent.

[0045] like Figure 4 As shown, in one embodiment, the water distribution assembly 32 is also connected to an aeration device (not shown) to improve the reliability of water distribution. The water distribution assembly 32 can be a publicly available flow equalization mesh plate, with at least two layers to facilitate aeration between the two layers by the aeration device.

[0046] The modified adsorption filter layer 33 includes, from bottom to top, a zeolite filter layer, a modified attapulgite filter layer, and an iron-manganese oxide modified activated carbon filter layer.

[0047] The support layer 35 is a graded pebble support layer 35, and a grid bracket is provided at the bottom of the graded pebble support layer 35. The thickness of the support layer 35 is 150-300mm, and the total thickness of the modified adsorption filter material layer 33 is 800-1200mm.

[0048] The ultrafiltration membrane assembly 34 includes a membrane support, multiple bundles of hollow fiber ultrafiltration membrane fibers, a water collection manifold, and a membrane connector (not shown). The multiple bundles of hollow fiber ultrafiltration membrane fibers are evenly arranged in a flat pattern on the membrane support. The inner cavity of each hollow fiber ultrafiltration membrane fiber is connected to the water collection manifold, which is connected to the bottom of the secondary adsorption retention tank 22. The pore size of the hollow fiber ultrafiltration membrane fibers is 0.01 μm to 0.1 μm.

[0049] The ultrafiltration membrane module 34 is used to physically intercept colloidal radionuclides, fine chelated precipitates, and suspended particulate matter in wastewater, and to prevent fine filter media particles in the modified adsorption filter layer 33 from being lost with the water flow, thereby further reducing the turbidity and radioactive content of the effluent, ensuring the cleanliness of the water entering the subsequent three-stage deep purification tank 23, and protecting the subsequent ion exchange resin from being contaminated by colloids and suspended solids.

[0050] In a preferred embodiment, the aeration device employs a microporous aeration disc, and the reliability of water distribution is improved through the two layers of equal flow mesh plates of the water distribution component 32.

[0051] The zeolite filter media layer (thickness 200-300mm): uses Na + Exchange-modified zeolite (particle size 2-4mm, specific surface area ≥500m² / g) exhibits an adsorption rate ≥95% for alkaline earth metal nuclides such as strontium and cesium; the modified attapulgite filter media layer (thickness 300-400mm): ... through Fe... 3+ Impregnation modification (Fe) 3+ With a loading of 1.5-2.0% w / w, the adsorption rate for heavy metal nuclides such as uranium and radium is ≥92%; the iron-manganese oxide modified activated carbon filter layer (thickness 300-500 mm): the surface is coated with a MnO2 / Fe2O3 composite coating (thickness 2-5 μm), with an adsorption rate for colloidal nuclides such as cobalt and strontium ≥98%. The thickness and functional sequence of the three filter layers are dynamically matched based on the nuclide migration characteristics. Zeolite is used to capture easily soluble nuclides first, then attapulgite is used to fix heavy metal precipitates, and finally modified activated carbon is used to retain colloidal nuclides, forming a gradient adsorption chain, which improves the total radionuclide removal rate from that of traditional single-layer filter media.

[0052] like Figure 4 As shown, in one embodiment, the modular ion exchange resin column group 37 includes at least two sets of resin column series units arranged in parallel. Each set of resin column series units includes at least three ion exchange resin columns connected in series in sequence. Each ion exchange resin column has an independent control valve at its inlet and outlet ends. The ion exchange resin column is filled with selective ion exchange resin for radionuclides.

[0053] The pool assembly 3 is also equipped with a resin regeneration liquid filling port and a regeneration waste liquid recovery port (not shown) corresponding to the modular ion exchange resin column group 37. The regeneration waste liquid recovery port can be connected to the water inlet pipe 15 through a pipeline for easy return and reprocessing.

[0054] Furthermore, each ion exchange resin column in the modular ion exchange resin column assembly 37 is connected to the pipeline via a quick-connect coupling. When the online detection component detects that the concentration of radionuclides in the effluent of a certain resin column series unit has increased to a set threshold, the control valve of that unit can be closed to isolate it from the system, and it can be regenerated online through the resin regeneration liquid injection port, while other parallel units continue to operate, ensuring continuous operation of the system without shutdown. The regeneration waste liquid is returned to the inlet pipe 15 for reprocessing through the regeneration waste liquid recovery port.

[0055] In a preferred embodiment, the resin type of the selective ion exchange resin is dynamically matched to the nuclide distribution: Dowex 1X8 resin is used when the uranium content is >45%, Chelex 100 resin is used when the strontium content is >30%, and Purolite S950 resin is used when the cobalt content is >20%.

[0056] like Figure 4 As shown, in one embodiment, the compliant water discharge pipe 4 is equipped with an electric control valve, and the non-compliant water return pipe 10 is also equipped with a return pump 9, facilitating reliable control of the return flow. Both the electric control valve and the non-compliant water return pipe 10 are electrically connected to the online radionuclide detection component and the online pH detection component, used to automatically switch between drainage and return flow modes based on the detection results.

[0057] For example, the preset threshold for radioactive nuclides is ≤5 Bq / L and the pH threshold is 6.0-8.0. When the detection exceeds the standard, the reflux pump 9 is automatically started and the electric control valve is closed; when the standard is met, the electric control valve is automatically opened, realizing closed-loop intelligent control.

[0058] like Figure 4 As shown, in one embodiment, the cascading conveying assembly includes a cascading pipe 38 and a cascading pump 39. One end of the cascading pipe 38 is connected to the bottom of the previous stage tank, and the other end of the cascading pipe 38 is connected to the top of the next stage tank. The cascading pump 39 is mounted on the cascading pipe 38.

[0059] It should be noted that, in order to adapt to the installation and arrangement of the flow conveying components, a fixed vertical baffle plate can be installed in the secondary adsorption interception tank 22 to ensure the convenient and reliable installation of the water distribution component 32, the modified adsorption filter media layer 33, the ultrafiltration interception membrane component 34 and the support layer 35. The selection can be made according to the actual scenario, without limitation or elaboration.

[0060] In one optional embodiment, the pool assembly 3 can be covered with a radiation shielding plate, and a first radiation shielding lining layer, a second radiation shielding lining layer, a third radiation shielding lining layer, and a fourth radiation shielding lining layer can be respectively provided on the cavity walls of the pre-settling and conditioning pool 20, the primary chelation treatment pool 21, the secondary adsorption and interception pool 22, and the tertiary deep purification pool 23 to form a fully enclosed radiation shielding and seepage-proof cavity.

[0061] The radiation shielding plate, the first radiation shielding lining layer, the second radiation shielding lining layer, the third radiation shielding lining layer, and the fourth radiation shielding lining layer all adopt a lead-boron polyethylene-high-density polyethylene-steel fiber reinforced concrete composite layer structure. The composite layer structure consists of an anti-corrosion inner lining layer, a lead-boron polyethylene shielding layer, a high-density polyethylene anti-seepage layer, and a steel fiber reinforced concrete structural layer from the inside out.

[0062] In one optional embodiment, the top of the pre-sedimentation conditioning tank 20, the primary chelation treatment tank 21, the secondary adsorption interception tank 22, and the tertiary deep purification tank 23 are all provided with an openable and closable shielding cover (not shown), and the inner side of the shielding cover is provided with a radiation shielding layer for easy maintenance.

[0063] The above embodiments of the present invention provide a multi-stage treatment tank for radioactive wastewater from a chemical plant. Wastewater enters a pre-sedimentation and equalization tank 20 through an inlet pipe 15. A rotating pipe 19 driven by a motor 2 drives a scraper 28 to scrape off the sludge from the inner wall of the settling plate 26, and mixes with the reagents added by the pH adjustment dosing component. Subsequently, it flows into a primary chelation treatment tank 21, where it reacts fully with the reagents added by the chelating agent dosing component under the action of a vortex stirring component 5 to form sediment. The sludge is deposited on a guide platform 30 and then pumped to a temporary storage chamber by a sludge discharge pump 11. The supernatant is lifted by a flow pump 39 into a secondary adsorption and interception tank. 22. The water flows sequentially through the water distribution assembly 32, the modified adsorption filter layer 33 (zeolite / attapulgite / modified activated carbon), and the ultrafiltration membrane assembly 34 for gradient adsorption and physical retention. Then it enters the three-stage deep purification tank 23 and flows through the modular ion exchange resin column group 37 to remove dissolved nuclides. Finally, it enters the terminal detection tank 24. If the radioactive nuclide is ≤5Bq / L and the pH is between 6.0 and 8.0, it is discharged through the qualified water discharge pipe 4. Otherwise, the return pump 9 is started and the water is returned to the front end for reprocessing through the unqualified water return pipe 10. The entire process is protected by a radiation shielding structure.

[0064] In summary, this invention achieves highly efficient deep purification of radioactive wastewater from chemical plants, fully automated operation, and zero risk of human radiation exposure by combining a multi-stage series process with a dynamic nuclide matching strategy (intelligent selection of chelating agents / adsorption filter media / resins) and closed-loop intelligent reflux control.

[0065] The control, model, and circuit connection of each component are not specifically limited, and can be flexibly configured in practical applications. All circuits, electronic components, and modules involved are existing technologies, which can be fully implemented by those skilled in the art, and need not be elaborated upon. Furthermore, the scope of protection of this invention does not involve improvements to the software and methods.

[0066] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0067] In the description of this specification, references to terms such as "embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0068] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A multi-stage treatment tank for radioactive wastewater from a chemical plant, comprising a tank assembly (3), characterized in that, The pool assembly (3) includes a pre-sedimentation and conditioning pool (20), a primary chelation treatment pool (21), a secondary adsorption and interception pool (22), a tertiary deep purification pool (23), and a terminal detection pool (24) connected in series along the sewage flow direction. Adjacent pools are connected by a tiered flow conveying assembly. The pre-sedimentation tank (20) has a sedimentation plate (26) on the upper inner side, a vertical partition plate (25) on the lower side of the sedimentation plate (26), a rotating tube (19) on the middle of the sedimentation plate (26) and a scraper plate (28) on the rotating tube (19) that cooperates with the inner wall of the sedimentation plate (26), a motor (2) connected to the rotating tube (19) on the outer side of the tank assembly (3), a water inlet pipe (15) on one end of the rotating tube (19), and a pH adjustment and dosing component connected to the rotating tube (19) on the tank assembly (3). The primary chelation treatment tank (21) is equipped with multiple sets of staggered baffles (31) inside. The multiple sets of baffles (31) form a continuous S-shaped baffle channel. The uppermost baffle (31) is equipped with a vortex stirring component (5) on its water-facing surface. The tank assembly (3) is equipped with a chelating agent dosing component that is connected to the upper part of the primary chelation treatment tank (21). The secondary adsorption and retention tank (22) is provided with a water distribution assembly (32), a modified adsorption filter media layer (33), an ultrafiltration retention membrane assembly (34), and a support layer (35) from bottom to top. The three-stage deep purification tank (23) is equipped with a horizontal partition (36), and a modular ion exchange resin column group (37) is provided on the horizontal partition (36). The terminal detection pool (24) is equipped with an online detection component. The lower part of the terminal detection pool (24) is equipped with a qualified water discharge pipe (4) and an unqualified water return pipe (10), and the unqualified water return pipe (10) is connected to the water inlet pipe (15).

2. The multi-stage treatment tank for radioactive wastewater from a chemical plant according to claim 1, characterized in that, The sedimentation plate (26) has an arc-shaped structure. The sedimentation plate (26) includes a filter screen and a baffle plate. The filter screen is set on the side close to the primary chelation treatment tank (21), and the baffle plate is set on the side away from the primary chelation treatment tank (21). The upper end of the filter screen is fixed to the top of the pre-settling and regulating tank (20). A sludge discharge gap is provided between the baffle plate and the side cavity wall of the pre-settling and regulating tank (20). The vertical partition (25) is located on the lower side between the water-blocking plate and the filter screen plate. The side of the vertical partition (25) away from the primary chelation treatment tank (21) forms a radioactive sludge temporary storage chamber. The tank assembly (3) is provided with a sludge discharge port (13) that communicates with the bottom of the radioactive sludge temporary storage chamber.

3. The multi-stage treatment tank for radioactive wastewater from a chemical plant according to claim 1 or 2, characterized in that, The scraper (28) is a hollow structure. The mixing chamber (43) of the scraper (28) is connected to the inner cavity of the rotating tube (19). Multiple water outlet holes (40) connected to the mixing chamber (43) are opened on the side of the outer end of the scraper (28) away from its rotation direction. Multiple rows of baffle blocks (41) and baffle blocks (42) are fixed in the mixing chamber (43) in an alternating manner, and the unit blocks of baffle blocks (41) and baffle blocks (42) are evenly staggered; multiple scraper blades (28) are evenly distributed around the rotating tube (19).

4. The multi-stage treatment tank for radioactive wastewater from a chemical plant according to claim 1, characterized in that, The pH adjustment dosing assembly includes a storage tank (8), a dosing pipe (17), and a dosing pump (16). The storage tank 2 (8) is fixed on the pool body assembly (3). One end of the addition pipe 2 (17) is connected to the bottom of the storage tank 2 (8). The addition pump 2 (16) is installed on the addition pipe 2 (17). The other end of the addition pipe 2 (17) is connected to the connecting ring (18). The connecting ring (18) is rotatably sleeved on the rotating pipe (19). The rotating pipe (19) has a connecting hole that communicates with the inner cavity of the connecting ring (18). The water inlet pipe (15) is rotatably connected to the rotating pipe (19), and the water inlet pipe (15) is fixed to the pool assembly (3) through the water inlet pipe bracket (14).

5. The multi-stage treatment tank for radioactive wastewater from a chemical plant according to claim 1, characterized in that, The chelating agent dosing assembly includes a storage tank (7), an addition pipe (29), and an addition pump (6). The storage tank (7) is fixed to the top of the pool assembly (3), one end of the addition pipe (29) is connected to the bottom of the storage tank (7), the addition pump (6) is installed on the addition pipe (29), and the other end of the addition pipe (29) is connected to the side of the upper end of the primary chelation treatment pool (21) near the pre-settling and regulating pool (20). The storage tank (7) contains a radionuclide chelating agent, which is one or a mixture of diethyldithiocarbamate, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, and diethylenetriaminepentaacetic acid.

6. The multi-stage treatment tank for radioactive wastewater from a chemical plant according to claim 1, characterized in that, The vortex stirring assembly (5) includes a mounting base (46), a linear telescopic cylinder (49), an arc telescopic cylinder (47), a drive shaft (44), a vortex impeller (45), and a second motor (48). The mounting base (46) is located on the upper side of the baffle plate (31) at the top. The cylinder body of the linear telescopic cylinder (49) is fixed to the top of the pool assembly (3). Its telescopic spindle is hinged to the mounting base (46). The arc-shaped telescopic cylinder (47) is located between the telescopic spindle of the linear telescopic cylinder (49) and the mounting base (46). The drive shaft (44) is provided with multiple shafts and is evenly distributed on one side of the mounting base (46) near the baffle plate (31). The vortex impeller (45) is fixed to the end of the drive shaft (44) away from the mounting base (46). The inner side of the mounting base (46) is fixed with a pulley (51) on the drive shaft (44). Two adjacent pulleys (51) are connected by a transmission belt (50). The second motor (48) is fixed on the mounting base (46) and is connected to one of the drive shafts (44). The plane of rotation of the vortex impeller (45) forms an angle of 45°-60° with the direction of water flow in the S-shaped baffle channel.

7. The multi-stage treatment tank for radioactive wastewater from a chemical plant according to claim 2, characterized in that, The bottom of the primary chelation treatment tank (21) is fixed with a cone-shaped guide platform (30). The bottom end of the primary chelation treatment tank (21) near the pre-sedimentation and conditioning tank (20) is connected to the upper part of the radioactive sludge temporary storage chamber through a sludge discharge pipe (12), and a sludge discharge pump (11) is installed on the sludge discharge pipe (12).

8. The multi-stage treatment tank for radioactive wastewater from a chemical plant according to claim 1, characterized in that, The water distribution component (32) is connected to the aeration device. The water distribution component (32) has at least two layers of equal flow mesh plate structure, and the aeration end of the aeration device is located between the two layers of equal flow mesh plate. The modified adsorption filter media layer (33) consists of, from bottom to top, a zeolite filter media layer, a modified attapulgite filter media layer, and an iron-manganese oxide modified activated carbon filter media layer. The support layer (35) is a graded pebble support layer, and a grid bracket is provided at the bottom of the support layer (35); The ultrafiltration membrane assembly (34) includes a membrane support, multiple bundles of hollow fiber ultrafiltration membrane fibers, a water collection manifold and a membrane connector. The hollow fiber ultrafiltration membrane fibers are evenly arranged on the membrane support in a flat manner. The inner cavity of the hollow fiber ultrafiltration membrane fibers is connected to the water collection manifold, and the water collection manifold is connected to the bottom of the secondary adsorption retention tank (22).

9. The multi-stage treatment tank for radioactive wastewater from a chemical plant according to claim 1 or 8, characterized in that, The modular ion exchange resin column group (37) adopts a combination of parallel and series arrangement structure, including at least two sets of resin column series units arranged in parallel. Each set of resin column series units includes at least three ion exchange resin columns connected in series in sequence. Each ion exchange resin column has an independent control valve at the inlet and outlet ends. The ion exchange resin column is filled with a selective ion exchange resin for radionuclides.

10. The multi-stage treatment tank for radioactive wastewater from a chemical plant according to claim 1, characterized in that, The online detection component includes an online radionuclide detection component and an online pH detection component; The qualified water discharge pipe (4) is equipped with an electric control valve, and the unqualified water return pipe (10) is equipped with a return pump (9). The electric control valve and the return pump (9) are both electrically connected to the radioactive nuclide online detection component and the pH online detection component.

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