Metal surface treatment wastewater inorganic salt separation and reuse process and wastewater treatment system

Abstract

The present invention discloses a process for separating and reusing inorganic salts from metal surface treatment wastewater and a wastewater treatment system. By integrating multiple treatment technologies such as a grid, a regulating tank, a neutralization tank, electroflocculation, biological contact oxidation, resin exchange, nanofiltration, reverse osmosis, and ozone oxidation, the grid can intercept large-particle impurities, the regulating tank can balance water quality and quantity, and then sequentially perform operations such as neutralization, electroflocculation, and precipitation to provide a good treatment environment for the separation of metal ions. Subsequently, heavy metals are removed through a resin water treatment unit, organic matter is degraded through biological contact oxidation, and deep filtration is performed by an HMF unit. The system is then mixed with low-concentration wastewater and separated from salts and water through nanofiltration and reverse osmosis. This system can achieve wastewater treatment and extract most of the sodium and magnesium ions in the wastewater, realizing resource reuse of the wastewater. Furthermore, the various links in the process are closely coordinated, solving the problems of lengthy, inefficient, and long and incomplete separation times in traditional processes.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and more specifically to a process for separating and recycling inorganic salts from metal surface treatment wastewater, and also to a wastewater treatment system. Background Art

[0002] In the metal surface treatment industry, processes such as electroplating and anodizing generate large amounts of wastewater. This wastewater often contains a variety of metal ions, with high concentrations of sodium and magnesium ions. Without effective treatment, direct discharge of this wastewater not only causes severe environmental pollution but also wastes valuable resources.

[0003] At present, traditional wastewater treatment methods have many problems in separating sodium and magnesium ions, such as low sodium and magnesium ion separation efficiency, which leads to waste of sodium and magnesium ions and other related raw materials, resulting in high costs and high emission pressure.

[0004] Therefore, a new solution needs to be proposed to solve this problem. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a process for separating and recycling inorganic salts from metal surface treatment wastewater and a wastewater treatment system.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A process for separating and recycling inorganic salts from metal surface treatment wastewater comprises the following steps:

[0008] Step 1: Filter the high-concentration wastewater through a grid to remove solid waste residue in the wastewater;

[0009] Step 2: The high-concentration wastewater after grating filtration flows into the regulating tank to regulate and balance the water volume and water quality of the wastewater;

[0010] Step 3: The high-concentration wastewater flowing out of the regulating tank enters the neutralization tank to adjust the pH value of the wastewater;

[0011] Step 4: The high-concentration wastewater flowing out of the neutralization tank enters the electro-flocculation unit to form flocs in the wastewater;

[0012] Step 5: The high-concentration wastewater flowing out of the electro-flocculation unit enters the sedimentation tank for solid-liquid separation;

[0013] Step 6: The supernatant of the sedimentation tank enters the resin water treatment unit 1, which is filled with exchange resin 1 to remove heavy metal ions. After treatment, the exchange resin 1 in the resin water treatment unit 1 is eluted with HCl, and the eluted waste liquid is subjected to heavy metal recovery treatment.

[0014] Step 7: The high-concentration wastewater after being treated by the resin water treatment device 1 enters the biological contact oxidation tank. The biological contact oxidation tank is filled with biological fillers, and the organic matter in the wastewater is degraded under the action of microorganisms;

[0015] Step 8: The high-concentration wastewater flowing out of the biological contact oxidation tank enters the HMF unit, and the high-intensity submerged membrane filtration unit uses PVDF hollow fiber membrane for filtration;

[0016] Step 9: The low-concentration metal wastewater directly enters the HMF unit and is mixed with the high-concentration wastewater; the mixed wastewater is treated by membrane filtration in the HMF unit;

[0017] Step 10: The mixed wastewater after being treated by the HMF unit enters the NF unit, and the mixed wastewater is separated by a nanofiltration membrane;

[0018] Step 11: The produced water obtained after the NF unit treatment enters the NF unit water production pool, and the wastewater in the NF unit water production pool enters the RO unit 1 for reverse osmosis separation treatment;

[0019] Step 12: The produced water obtained after the treatment of RO unit 1 enters the RO unit 1 water production pool, and the water in the RO unit 1 water production pool can be reused;

[0020] In step 13, concentrated water is obtained by treatment in the RO unit 1. When the sodium chloride concentration in the concentrated water is lower than the preset value, the concentrated water will be processed again in step 12; when the sodium chloride concentration in the concentrated water is not lower than the preset value, the concentrated water enters the concentrated water tank of the RO unit 1 and can be reused as sodium chloride solution;

[0021] Step 14: The concentrated water obtained after the NF unit treatment enters the NF unit concentrated water tank;

[0022] Step 15: The wastewater from the NF unit concentrate tank enters the ozone oxidation tank. Ozone is used to oxidize and decompose the residual organic matter and reducing substances in the wastewater.

[0023] Step 16: The wastewater after being treated in the ozone oxidation tank enters the resin water treatment unit 2, which is filled with the exchange resin 2 to perform ion exchange treatment;

[0024] Step 17: The produced water obtained by the resin water treatment device 2 enters the NF unit water production pool and is mixed with the produced water obtained in step 11;

[0025] Step 18: The exchange resin in the resin water treatment unit 2 is eluted with HCl, and the eluate contains adsorbed ions; the eluted water enters the RO unit 2, and the water obtained after the treatment of the RO unit 2 enters the RO unit 2 water production tank, and the water in the RO unit 2 water production tank can be reused;

[0026] In step 19, concentrated water is obtained after treatment in RO unit 2. When the magnesium chloride concentration in the concentrated water is lower than the preset value, the concentrated water will be processed again in step 18; when the magnesium chloride concentration in the concentrated water is not lower than the preset value, the concentrated water enters the concentrated water tank of RO unit 2 and can be reused as magnesium chloride solution.

[0027] The present invention is further configured such that, in step 2, the regulating tank is connected to the screen through a pipe, and the wastewater flows out of the screen into the regulating tank by gravity or a pumping system; a stirring device is provided inside the regulating tank for uniform stirring.

[0028] The present invention is further configured such that, in step three, a pH monitoring and acid-base addition system is provided in the neutralization tank, which can detect the pH value in the neutralization tank and can add an acid-base regulator to the neutralization tank according to the pH value.

[0029] The present invention is further configured such that, in step six, the resin water processor 1 is connected to the sedimentation tank via a pipeline, and a flow control device is installed on the pipeline to detect the flow rate entering the resin water processor 1 from the sedimentation tank.

[0030] The present invention is further configured such that, in step six, the exchange resin in the resin water treatment device 1 is a heavy metal ion adsorption resin, and the heavy metal-containing solution obtained by elution is used to recycle the heavy metal inorganic salt.

[0031] The present invention is further configured such that, in step seven, the resin water treatment unit 1 is connected to the biological contact oxidation tank via a pipeline, and an aeration system is provided in the biological contact oxidation tank to aerate the biological contact oxidation tank.

[0032] The present invention is further configured such that, in step nine, the low-concentration metal wastewater directly enters the HMF unit through a pipeline, and is mixed with the high-concentration wastewater in the HMF unit.

[0033] The present invention is further configured such that the exchange resin in the second resin water treatment unit is a magnesium ion adsorption resin, and the magnesium chloride-containing solution obtained by elution is subsequently used for recycling the magnesium chloride salt.

[0034] The present invention is further configured such that, in step 13 and step 19, concentration detection sensors are installed at the concentrate outlet of RO unit 1 and RO unit 2 to detect the concentration in the concentrate; and two branches are formed at the concentrate outlet, and the on-off status of the two branches is controlled by valves.

[0035] The present invention also provides a wastewater treatment system, including an electric flocculation unit, the electric flocculation unit including a cathode tube, an anode core rod, and a buffer chamber, the cathode tube being vertically arranged and divided into a plurality of tube segments distributed from top to bottom, adjacent tube segments being connected by the buffer chamber, the tube segments having tube lumens, the buffer chamber having a buffer inner cavity, the tube lumens and the buffer inner cavity being interconnected to form a wastewater channel communicating with each other;

[0036] The anode core rod is coaxially arranged in the tube cavity and passes through the buffer cavity;

[0037] The upper end of the anode core rod is mounted on the upper hoisting portion to achieve hoisting limit, and the lower end of the anode core rod is in a hanging shape;

[0038] A support assembly is installed in the buffer inner cavity, and the support assembly is used to limit the horizontal direction of the anode core rod.

[0039] The present invention is further configured such that the support assembly includes a support tube, a first support block, and a second support block; the support tube is fixedly mounted on the lower side wall of the buffer inner cavity; the support tube is provided with a gap portion penetrating the inner and outer circumferences;

[0040] The present invention is further configured such that both support block 1 and support block 2 are annular structures, support block 1 is installed on the inner circumference of the support cylinder, support block 2 is installed on the outer circumference of the anode core rod, and at least part of support block 2 extends into the inner circumference of support block 1 to achieve circumferential pressure limiting.

[0041] The present invention is further configured such that the inner circumference of the support block 1 and the outer circumference of the support block 2 are in an inverted conical structure adapted to each other, and the inner circumference of the support block 1 and the outer circumference of the support block 2 are partially fitted to each other and press against each other;

[0042] The present invention is further configured such that the outer periphery of the support block 1 is adapted to slide up and down with the support tube, and a support spring is installed on the lower side of the support block 1, and the support spring is used to apply an upward force to the support block 1;

[0043] The present invention is further configured such that an upper section of the inner circumference of the support tube is fixedly connected to a limit stop ring, and the limit stop ring is used to block a limit to the support block.

[0044] The present invention is further configured such that the lower end of the anode core rod is inserted into the lower sleeve portion, for limiting the horizontal position of the anode core rod and enabling vertical relative movement; and the upper hoisting portion can be adjusted up and down.

[0045] The present invention is further configured such that connection ports are provided on the upper and lower sides of the buffer bin, and the connection ports on the upper and lower sides are opposite to each other; a cylindrical filter residue net is provided at the upper end of the support tube, and the filter residue net is an annular cylindrical structure, the lower end of the filter residue net is connected to the upper end of the support tube, and the upper end of the filter residue net is connected to the outer periphery of the connection port on the upper side.

[0046] The present invention is further configured such that the inner diameter of the buffer cavity is larger than the inner diameter of the tube cavity, and the buffer cavity is used to buffer the flocculated residue in the wastewater; the outer periphery of the buffer bin is connected to two slag discharge pipes, which are respectively used for the inlet and outlet of wastewater containing flocculated residue.

[0047] The present invention is further configured such that two slag discharge ports are respectively opened on the left and right sides of the buffer bin, the two slag discharge ports are respectively connected to two slag discharge pipes, the lower side of the slag discharge port is flush with the lower side surface of the buffer inner cavity; the gap portion on the outer periphery of the support tube corresponds to the height of the slag discharge port.

[0048] The present invention is further configured such that the electric flocculation unit also includes a circulation pump, a filter, a circulation main circuit and a circulation pipeline; the circulation pump and the filter are both installed in the circulation pipeline, the filter is located on the water inlet side of the circulation pump, and the two slag discharge pipes on the outer periphery of the buffer bin are respectively connected to the two ends of the circulation pipeline.

[0049] In summary, the present invention has the following beneficial effects:

[0050] By integrating multiple treatment technologies, including screens, regulating tanks, neutralization tanks, electrocoagulation, biological contact oxidation, resin exchange, nanofiltration, reverse osmosis, and ozone oxidation, the screens can intercept large impurities, while the regulating tanks balance water quality and quantity. Neutralization, electrocoagulation, and precipitation are then sequentially performed to provide an optimal treatment environment for metal ion separation. Heavy metals are then removed through a resin water treatment unit, while biological contact oxidation degrades organic matter. The HMF unit performs deep filtration and is mixed with low-concentration wastewater, which is then separated from the water through nanofiltration and reverse osmosis. This achieves wastewater treatment, extracting most of the sodium and magnesium ions from the wastewater and enabling wastewater resource reuse. Furthermore, the close coordination of each process link addresses the challenges of lengthy, inefficient, and long, incomplete separation times associated with traditional processes.

[0051] By detecting the concentration at the concentrated water outlet of RO unit 1 and RO unit 2, the flow direction of the concentrated water can be switched according to the concentration level, low-concentration wastewater can be recycled, and the aggregation of sodium and magnesium ions can be achieved to form a high-concentration solution, thereby enabling the reuse of high-concentration sodium and magnesium ion solutions, thereby reducing resource waste and lowering the cost of purchasing raw materials. Moreover, the reuse of the solution can also reduce emissions and the risk of secondary pollution, and is lower in cost and pollution than traditional treatment processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a three-dimensional diagram of a wastewater treatment system in Example 2;

[0053] Figure 2 is a cross-sectional view of a wastewater treatment system in Example 2;

[0054] Figure 3 It is an enlarged cross-sectional view of a wastewater treatment system in Example 2;

[0055] Figure 4Schematic diagram of the force structure of the anode core rod in Example 2;

[0056] Figure 5 This is a schematic structural diagram of the support assembly and the anode core rod in Example 2;

[0057] Figure 6 for Figure 4 A partial enlarged view of the

[0058] Figure 7 This is a schematic structural diagram of the circulation pipeline in Example 2;

[0059] Figure 8 This is a flow chart of Example 1.

[0060] Figure numerals: cathode tube 1; tube section 100; tube cavity 101; anode core rod 2; upper end 201; upper hanging part 2011; lower end 202; lower sleeve part 2021; buffer bin 3; buffer inner cavity 301; connecting port 302; slag discharge port 303; slag discharge pipe 4; support assembly 5; support cylinder 51; gap portion 511; limit retaining ring 512; support block 1 52; inner peripheral surface 521; support block 2 53; outer peripheral surface 531; support spring 54; filter residue net 6; circulation pump 7; circulation pipeline 71; filter 8. DETAILED DESCRIPTION

[0061] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0062] Example 1

[0063] This embodiment discloses a process for separating and recycling inorganic salts from metal surface treatment wastewater. Figure 8 As shown, metal surface treatment wastewater can be treated, and the wastewater is divided into high-concentration wastewater and low-concentration wastewater. The concentration level can be differentiated according to specific treatment requirements, and the preset values ​​for differentiation can be preset. Through this treatment process, heavy metal pollution in wastewater can be separated and treated separately; high-concentration sodium chloride and magnesium chloride can be easily separated and reused as corresponding solutions; in addition, pure water with higher purity can be separated and reused as process water. It can separate different metal ion pollution in wastewater and realize the recycling of resources.

[0064] The process for separating and reusing inorganic salts from metal surface treatment wastewater includes the following steps:

[0065] Step 1: Screen filter the high-concentration wastewater to remove solid waste residue in the wastewater; high-concentration metal surface treatment wastewater first enters the screen, which acts as a physical filter. Its fence or screen structure can intercept larger suspended matter and impurities in the wastewater, such as metal debris, large pieces of solid waste residue, etc., to avoid blockage and wear of equipment, and ensure the normal operation of the entire treatment system.

[0066] In step two, the high-concentration metal surface treatment wastewater, after being filtered through the screen, flows into the regulating tank. Within this tank, the wastewater's volume and quality are regulated and balanced, maintaining a relatively stable state over time. During the metal surface treatment process, the wastewater generated may experience fluctuations in flow rate and water quality. The regulating tank acts as a buffer, protecting subsequent treatment units from significant fluctuations in water volume and quality, thereby ensuring the stability and continuity of the subsequent treatment process.

[0067] In step 2, the regulating tank is connected to the screen through a pipe, and the wastewater flows out of the screen into the regulating tank by gravity or a pumping system; a stirring device is provided inside the regulating tank to stir the wastewater evenly.

[0068] In step three, the wastewater flowing out of the equalization tank enters the neutralization tank to adjust the pH value of the wastewater. Since the pH value of the wastewater generated by different metal surface treatment processes may be different, and subsequent treatment steps such as electrocoagulation have certain requirements for the pH value of the wastewater, the pH value of the wastewater needs to be adjusted to an appropriate range. A pH monitoring and acid-base addition system is set up in the neutralization tank. By adding acid-base regulators and based on the data fed back by the online pH monitoring device, the amount of acid and base added is precisely controlled to achieve the required pH value range, creating good chemical conditions for subsequent treatment.

[0069] In step four, the neutralized, high-concentration metal surface treatment wastewater enters the electroflocculation unit. This unit uses electrochemical reactions to generate metal hydroxide colloids with flocculation capabilities through electrodes (usually iron or aluminum electrodes). When a DC electric field is applied, the electrodes undergo redox reactions, and the generated metal ions hydrolyze to form colloids. These colloids can adsorb colloids, suspended particles, some heavy metal ions, and some organic matter in the wastewater, causing them to agglomerate into larger flocs, preparing for subsequent precipitation and separation.

[0070] In step five, the electrocoagulated wastewater enters a sedimentation tank for solid-liquid separation. Gravity settles the larger flocs formed in the sedimentation tank to the bottom. The precipitated sludge, which contains a large amount of impurities, can be collected by equipment such as a scraper for subsequent sludge treatment or resource recycling. The supernatant liquid can then be processed for the next stage.

[0071] In step six, the supernatant from the sedimentation tank enters Resin Water Treatment Unit 1, which is filled with Exchange Resin 1 to remove heavy metal ions. Exchange Resin 1 is designed to remove heavy metal ions while retaining sodium and magnesium ions. This effectively removes heavy metal contamination from the wastewater, preventing it from interfering with subsequent biological treatment. It can also be used for heavy metal recovery. After treatment, the Exchange Resin 1 in Resin Water Treatment Unit 1 is eluted with HCl, and the eluted wastewater is processed for heavy metal recovery.

[0072] In step six, the resin water treatment unit (1) is connected to the sedimentation tank via a pipeline. A flow control device is installed on the pipeline to monitor the flow rate from the sedimentation tank into the resin water treatment unit (1), ensuring that wastewater enters the resin water treatment unit (1) at an appropriate flow rate. The ion exchange resin (1) within the resin water treatment unit (1) has a certain adsorption capacity. When adsorption reaches saturation, its exchange capacity can be restored through backwashing and regeneration. Regeneration is generally performed using an acid-base solution and elution with hydrochloric acid. The eluate can be used to recover heavy metals.

[0073] In step seven, the high-concentration wastewater, after treatment by the resin water treatment unit, enters the biological contact oxidation tank. The tank is filled with biological fillers, where microorganisms degrade organic matter in the wastewater. Microorganisms attach to the fillers to form a biofilm. Through their metabolic activity, the microorganisms break down organic matter into carbon dioxide, water, and harmless substances, reducing the content of organic pollutants in the wastewater.

[0074] In step seven, the resin water treatment unit 1 is connected to the biological contact oxidation tank via a pipeline. An aeration system is installed within the tank to aerate the interior of the tank, providing sufficient oxygen for the microorganisms to carry out aerobic metabolism. Under a certain hydraulic retention time and appropriate temperature and pH conditions, the microorganisms degrade organic matter.

[0075] In step eight, the high-concentration wastewater from the biological contact oxidation tank enters the HMF unit, a high-strength submerged membrane filtration unit that utilizes PVDF hollow fiber membranes. PVDF hollow fiber membrane filtration technology further removes microparticles, colloids, some organic matter, and some ions from the wastewater, improving wastewater treatment efficiency.

[0076] In step nine, low-concentration metal wastewater enters the HMF unit directly and mixes with high-concentration wastewater; the mixed wastewater is treated by membrane filtration in the HMF unit to achieve the overall treatment and resource recovery goals.

[0077] In step nine, the low-concentration wastewater enters the HMF unit directly through a separate pipe and is mixed with the high-concentration wastewater in the HMF unit. The mixing process can be achieved through simple pipe mixing or by setting a mixing device at the water inlet of the HMF unit to ensure that the wastewater is evenly mixed and receives the filtration treatment of the HMF unit together.

[0078] In step 10, the mixed wastewater treated by the HMF unit enters the NF unit, where it is separated by a nanofiltration membrane. The NF unit is a membrane separation process between ultrafiltration and reverse osmosis. It selectively intercepts divalent and multivalent ions and larger organic matter, while allowing monovalent ions and small molecules to pass through, thereby further separating and purifying the wastewater and improving the quality of the produced water. It also achieves the separation of monovalent and divalent inorganic salts, further separating and purifying the inorganic salts in the wastewater for subsequent recycling.

[0079] In step 11, the produced water from the NF unit enters the NF unit water production tank. The wastewater from the NF unit water production tank enters RO unit 1 for reverse osmosis separation. RO unit 1 utilizes a reverse osmosis membrane operating at high pressure, allowing only water molecules to pass through the membrane while retaining salts and other impurities. This further improves the purity of the produced water, making it suitable for reuse.

[0080] In step 12, the produced water obtained after the treatment of RO unit 1 enters the RO unit 1 water production tank. The water in the RO unit 1 water production tank can be reused; this part of water meets high water quality standards and can be directly reused in different links of the metal surface treatment process, such as rinsing water, cooling circulating water, etc., to achieve the recycling of water resources, reduce the demand for fresh water, and reduce production costs.

[0081] In step 13, concentrated water is obtained after treatment in the RO unit 1. When the sodium chloride concentration in the concentrated water is lower than the preset value, the concentrated water will be processed again in step 12; when the sodium chloride concentration in the concentrated water is not lower than the preset value, the concentrated water enters the concentrated water tank of the RO unit 1 and can be reused as sodium chloride solution.

[0082] In step 13, a concentration detection sensor is installed at the brine outlet of RO unit 1 to detect the concentration of the brine; and two branches are formed at the brine outlet, and the on-off status of the two branches is controlled by valves to realize the flow direction of the brine.

[0083] Step 14: The concentrated water obtained after the NF unit treatment enters the NF unit concentrated water pool. The nanofiltration concentrated water contains a high concentration of divalent ions and some organic matter, and needs further treatment to recover the resources or achieve standard discharge.

[0084] In step 15, the wastewater from the NF unit concentrate tank enters the ozone oxidation tank. The ozone oxidation tank uses the strong oxidizing properties of ozone to oxidize and decompose residual organic matter and reducing substances in the wastewater, improving the wastewater quality and creating better conditions for subsequent treatment.

[0085] In step 16, the wastewater treated in the ozone oxidation tank enters the resin water treatment unit 2, which is filled with exchange resin 2 for ion exchange treatment. The wastewater contains a high concentration of magnesium ions, which are exchanged using the ion exchange resin, further improving the water quality.

[0086] Step 17: The produced water obtained by the resin water treatment unit 2 enters the NF unit water production pool and is mixed with the produced water obtained in step 11 for subsequent reuse or further treatment to improve the comprehensive utilization efficiency of water.

[0087] In step 18, the exchange resin 2 in the resin water treatment unit 2 is eluted with HCl, and the eluate contains adsorbed ions; the produced water after elution enters the RO unit 2, and the produced water obtained after treatment in the RO unit 2 enters the RO unit 2 production water tank. The water in the RO unit 2 production water tank can be reused and can be used in occasions with higher water quality requirements, such as the final cleaning water in the metal surface treatment process or water for preparing chemical agents.

[0088] In step 19, concentrated water is obtained after treatment in the RO unit 2. When the magnesium chloride concentration in the concentrated water is lower than the preset value, the concentrated water will be processed again in step 18. When the magnesium chloride concentration in the concentrated water is not lower than the preset value, the concentrated water enters the concentrated water tank of the RO unit 2 and can be reused as magnesium chloride solution, thereby realizing resource reuse.

[0089] In step 19, a concentration sensor is installed at the brine outlet of RO unit 2 to detect the concentration of the brine. Two branches are formed at the brine outlet, and valves are used to control the flow of the brine. The brine flow direction is controlled by switching the valves based on the concentration detection results.

[0090] By integrating multiple treatment technologies, including screens, regulating tanks, neutralization tanks, electrocoagulation, biological contact oxidation, resin exchange, nanofiltration, reverse osmosis, and ozone oxidation, the screens can intercept large impurities, while the regulating tanks balance water quality and quantity. Neutralization, electrocoagulation, and precipitation are then sequentially performed, providing an optimal treatment environment for metal ion separation. Heavy metals are then removed through a resin water treatment unit, while biological contact oxidation degrades organic matter. The HMF unit performs deep filtration, and the water is then mixed with low-concentration wastewater, separating the salt from the water through nanofiltration and reverse osmosis. This completes wastewater treatment, extracting most of the sodium and magnesium ions from the wastewater and enabling wastewater resource reuse. Furthermore, the close coordination of each process link addresses the challenges of lengthy traditional processes and prolonged, incomplete separation times.

[0091] By detecting the concentration at the concentrated water outlet of RO unit 1 and RO unit 2, the flow direction of the concentrated water can be switched according to the concentration level, low-concentration wastewater can be recycled, and the aggregation of sodium and magnesium ions can be achieved to form a high-concentration solution, thereby enabling the reuse of high-concentration sodium and magnesium ion solutions, thereby reducing resource waste and lowering the cost of purchasing raw materials. Moreover, the reuse of the solution can also reduce emissions and the risk of secondary pollution, and is lower in cost and pollution than traditional treatment processes.

[0092] Example 2

[0093] This embodiment discloses a wastewater treatment system capable of treating wastewater by the process in the above embodiment. Figure 1-Figure 7 Provide detailed explanation.

[0094] Reference Figure 1 、 Figure 2 As shown, the wastewater treatment system in this embodiment includes an electro-flocculation unit, which includes a cathode tube 1, an anode core rod 2, and a buffer chamber 3. The cathode tube 1 is vertically arranged and divided into a plurality of tube segments 100 distributed from top to bottom. Adjacent tube segments 100 are connected by the buffer chamber 3. The tube segments 100 have a tube lumen 101, and the buffer chamber 3 has a buffer lumen 301.

[0095] The lumen 101 and the buffer lumen 301 are interconnected to form a wastewater channel that is interconnected from top to bottom. Specifically, connection ports 302 are respectively provided on the upper and lower side walls of the buffer bin 3, and the connection ports 302 on the upper and lower sides are opposite to each other.

[0096] The anode core rod 2 is coaxially inserted into the tubular cavity 101 and passes through the buffer inner cavity 301. The anode core rod 2 is inserted into the tubular cavity 101, forming an annular flow channel between the cathode tube 1 and the anode core rod 2 for transporting the wastewater to be treated. During the treatment process, the wastewater flows from bottom to top. The anode core rod 2 serves as the anode material for electroflocculation, and the cathode tube 1 serves as the cathode material for electroflocculation. During the electroflocculation process, the anode core rod 2 is lost. By adopting a tubular electroflocculation structure, the cathode material can be transferred to the outer tube body for wastewater transportation, and the anode core body is inserted in the middle. This can improve the reaction efficiency between the wastewater and the cathode and anode materials, thereby improving the efficiency of electroflocculation.

[0097] The cross-sections of the anode core rod 2 and the cathode tube 1 are both circular and coaxially mounted, which can keep the distance between the outer periphery of the anode core rod 2 and the inner periphery of the cathode tube 1 basically consistent. This ensures that the anode core rod 2 wears at a substantially consistent rate at each position on the periphery during wear, maintains a roughly cylindrical structure of the anode core rod 2, and maintains a relatively uniform and stable state during the reaction process.

[0098] Reference Figure 3 、 Figure 4 As shown, the upper end 201 of the anode core rod 2 is mounted on an upper hanging portion 2011. The upper hanging portion 2011 serves as a fixed support point to limit the hanging position, and the lower end 202 of the anode core rod 2 is suspended. The anode core rod 2 forms an upper hanging installation structure, which causes it to be pulled downward by gravity, thus preventing the anode core rod 2 from bending and further preventing the undesirable situation of direct contact between the anode core rod 2 and the cathode tube 1 caused by bending.

[0099] In order to maintain the installation stability of the anode core rod 2, a support assembly 5 can be installed in the buffer cavity 301 to limit the horizontal position of the anode core rod 2, thereby preventing the middle section of the anode core rod 2 from lateral bending displacement.

[0100] Reference Figure 5 、 Figure 6 As shown, the support assembly 5 includes a support tube 51, a support block 1 52 and a support block 2 53. The support tube 51 is a cylindrical structure that passes through from top to bottom. The lower side is fixedly installed on the lower side wall of the buffer cavity 301, and the support tube 51 is sleeved on the outer periphery of the anode core rod 2.

[0101] Specifically, the support tube 51 is installed above the connection port 302, opposite to the connection port 302 on the lower side of the buffer bin 3. This means that wastewater flowing upward from the connection port 302 directly enters the support tube 51. A gap 511 is formed on the sidewall of the support tube 51, extending through the inner and outer circumferences, allowing wastewater to flow through.

[0102] Both support block 1 52 and support block 2 53 are annular in structure. Support block 1 52 is mounted on the inner circumference of support cylinder 51, while support block 2 53 is mounted on the outer circumference of anode core rod 2. Support block 2 53 is fixedly connected to anode core rod 2. At least a portion of support block 2 53 extends into the inner circumference of support block 1 52, providing circumferential pressure and limiting.

[0103] The support tube 51 can limit the support block 1 52 , and the support block 1 52 and the support block 2 53 can be pressed against each other inside and outside to maintain axial limitation, ensure the position stability of the anode core rod 2, and avoid lateral deviation and bending.

[0104] Furthermore, the inner circumference 521 of support block 1 52 and the outer circumference 531 of support block 2 53 form mutually compatible inverted conical structures. The inner circumference 521 of support block 1 52 and the outer circumference 531 of support block 2 53 partially fit within each other and press against each other. The mutual pressure of the two conical surfaces enables automatic centering and positioning. Because the axes of both conical surfaces are coaxial with the axis of the cathode tube 1, this ensures that the anode core rod 2 remains coaxial with the cathode tube 1 after centering, maintaining the positional stability of the anode core rod 2.

[0105] Furthermore, the outer periphery of the support block 52 is adapted to slide up and down with the support tube 51, meaning that the support block 52 can slide up and down within the support tube 51, with the sliding direction being aligned with the axis of the cathode tube 1. A limit ring 512 is fixedly connected to the upper portion of the inner periphery of the support tube 51. The limit ring 512 is used to block the support block 52 and prevent it from sliding excessively upward and disengaging.

[0106] A support spring 54 is installed on the lower side of the support block 1 52. The lower end of the support spring 54 presses against the lower side wall of the buffer cavity 301, and the upper end presses against the lower side of the support block. The support spring 54 is used to apply an upward force to the support block 1 52 to form an upward elastic support.

[0107] Reference Figure 4 As shown, when the anode mandrel 2 is installed, its upper end 201 is suspended by the upper suspension portion 2011, creating an upward force that counteracts most of the weight of the anode mandrel 2. A plurality of support blocks 53 are fixed to the middle section of the anode mandrel 2. These blocks, in conjunction with other components of the support assembly 5, provide an upward support force, thereby counteracting part of the weight of the anode mandrel 2. Specifically, the support block 53 is primarily subject to the upward elastic force of the support spring 54. The support spring 54 is in a semi-compressed state, meaning that it is compressed and not fully compressed. The upward support provided by the support spring 54 primarily maintains the tapered surfaces of the support blocks 1 52 and 2 53 against each other, maintaining the upward and downward pressure and maintaining a state of automatic centering, while also partially supporting the anode mandrel 2.

[0108] The support assembly 5 provides auxiliary upward support for the middle section of the anode mandrel 2, distributing the deadweight of the anode mandrel 2 and preventing the anode mandrel 2 from bending due to excessive force during hoisting. Furthermore, since the support block 1 52 can be flexibly adjusted up and down, the distance between two adjacent support points of the anode mandrel 2 can also be adjusted, thereby preventing a section of the anode mandrel 2 from being subjected to forces in two opposing directions, which could cause the anode mandrel 2 to bend.

[0109] Reference Figure 4 As shown, a lower sleeve portion 2021 is provided at the lower end 202 of the anode core rod 2. The lower sleeve portion 2021 is not directly connected to the lower end 202 of the anode core rod 2. The lower sleeve portion 2021 is connected to other parts of the equipment to maintain a fixed position. A hole is formed in the lower sleeve portion 2021 that passes through the lower sleeve portion 2021 and is adapted to the outer diameter of the anode core rod 2. The anode core rod 2 is axially inserted into the hole in the lower sleeve portion 2021, which can limit the horizontal position of the anode core rod 2.

[0110] The upper hoisting portion 2011 can be adjusted up and down, and adaptive vertical relative movement can also occur between the lower end 202 of the anode mandrel 2 and the lower sleeve portion 2021. Through adjustment, the vertical height of the anode mandrel 2 can be adjusted, and the height position of the second support block 53 outside the anode mandrel 2 can be adjusted synchronously. When the height position of the second support block 53 is adjusted, the compression degree of the support spring 54 between the first support block 52 and the second support block 53 is changed, thereby adjusting the support provided by the support spring 54 to the anode mandrel 2.

[0111] Through detection, it is found that when the lifting force on the upper lifting part 2011 is too small, the upper lifting part 2011 can be adjusted downward appropriately, so that the anode core rod 2 and each support block 2 53 can be adjusted downward, so that the support spring 54 can be compressed more, and a greater supporting force can be provided, so that the force on each section of the anode core rod 2 is more uniform, and bending due to uneven force will not occur, thereby avoiding uneven electrocoagulation caused by bending.

[0112] During use, the outer circumference of the anode mandrel 2 gradually wears away as the device is used, reducing its diameter and weight. At this point, the combined support force of the support springs 54 may be greater than the weight of the anode mandrel 2, potentially causing the anode mandrel 2 to be subjected to opposing forces in the upper and lower directions, potentially causing the anode mandrel 2 to bend. Therefore, the position of the upper hanging portion 2011 can be adjusted to change the compression of the support springs 54. This allows the support force of the support springs 54 to be adjusted appropriately, maintaining the anode mandrel 2 in the proper hanging state and, consequently, maintaining it in a vertical installation position.

[0113] Further, refer to Figure 7 As shown, connection ports 302 are provided on both the upper and lower sides of the buffer bin 3, with the connection ports 302 facing each other vertically. Furthermore, multiple pairs of connection ports 302 are provided, and multiple groups of cathode tubes 1 are installed on both the upper and lower sides of the buffer bin 3, with each group of cathode tubes 1 forming a parallel, side-by-side structure.

[0114] The inner diameter of the buffer lumen 301 is larger than that of the tube lumen 101 and is used to buffer flocculated residue in the wastewater. The larger inner diameter of the buffer lumen 301 creates multiple buffer spaces in the middle section of the cathode tube 1. During the flocculation process, oversized flocs can be stored in the buffer lumen 301, preventing floc blockage in the cathode tube 1.

[0115] Since the various support components 5 of the middle section of the anode core rod 2 are installed in the buffer cavity 301 , the size of the installation location is relatively large, and thus it is less likely to be blocked, which is beneficial to the flow of wastewater in the buffer cavity 301 .

[0116] Furthermore, two slag discharge pipes 4 are connected to the periphery of the buffer bin 3. These two slag discharge pipes 4 are used to allow wastewater containing flocculated slag to enter and exit the buffer bin. The gap 511 on the periphery of the support tube 51 corresponds to the height of the slag discharge port 303. Two slag discharge ports 303 are respectively provided on the left and right sides of the buffer bin 3. These two slag discharge ports 303 are connected to the two slag discharge pipes 4, and the bottom of the slag discharge port 303 is flush with the bottom side of the buffer cavity 301.

[0117] By introducing fresh water into the buffer bin 3 from the slag discharge port 303, the buffer bin 3 can be flushed, and the accumulated wastewater in the buffer cavity 301 can be discharged, thereby reducing the wastewater circulation pressure in the cathode tube 1. Moreover, the gap 511 on the outer periphery of the support tube 51 corresponds to the height of the slag discharge port 303, so that the water flow output from the slag discharge port 303 can flush the accessories of the gap 511, thereby preventing excessive accumulation of flocs near the gap 511. During the flushing process, the anode core rod 2 can be raised and lowered. During the adjustment process, the support block 1 52, the support block 2 53 and the support spring 54 will be able to disturb the area near the gap 511 in the support tube 51, so that the flocs can flow more easily, and the accumulated wastewater can be pushed out to form a discharge of flocs.

[0118] In addition, the electric flocculation unit also includes a circulation pump 7, a filter 8, a circulation main line 72 and a circulation pipeline 71. The circulation pump 7 and the filter 8 are both installed in the circulation pipeline 71. The filter 8 is located on the water inlet side of the circulation pump 7. The two slag discharge pipes 4 on the periphery of the buffer bin 3 are respectively connected to the two ends of the circulation pipeline 71. The wastewater in the buffer cavity 301 is circulated and pumped by the circulation pump 7. It will be discharged from the slag discharge pipe 4 on one side and flow back from the other side, forming a circulating flow of wastewater. During the circulation process, the wastewater will circulate through the filter 8, which can separate and filter the flocs in the wastewater, and thus gradually remove the floc blockage. Specifically, the circulation pump 7 can be operated regularly, thereby alleviating the floc blockage in the buffer cavity 301, especially near the support assembly 5.

[0119] Furthermore, a cylindrical filter screen 6 is mounted on the upper end of the support tube 51. The filter screen 6 has an annular cylindrical structure, with its lower end connected to the upper end of the support tube 51, and its upper end connected to the outer periphery of the upper connection port 302. During the wastewater circulation process, it enters the lower connection port 302 of the buffer bin 3, passes through the gap 511 of the support tube 51, enters the space outside the support tube 51, then enters the inner periphery of the filter screen 6 through the filter screen 6, and is discharged from the upper connection port 302 of the support tube 51, entering the upper cathode tube 1 pipe section 100, thereby completing the wastewater circulation. Most of the flocs in the wastewater can be blocked within the support tube 51 and can be collected and processed along the circulation main circuit 72.

[0120] The filter residue screen 6 is generally installed only in 1-2 buffer bins 3 near the bottom, and is mainly used to process the initially entering wastewater and separate the excessive large particles of impurities mixed therein.

[0121] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A process for separating and reusing inorganic salts from metal surface treatment wastewater, characterized in that: The steps are as follows: Step 1: removing solid waste residue from high-concentration wastewater; Step 2: High-concentration wastewater flows into the regulating tank for regulation; Step 3: The high-concentration wastewater flowing out of the regulating tank enters the neutralization tank to adjust the pH value of the wastewater; Step 4: The high-concentration wastewater flowing out of the neutralization tank enters the electric flocculation unit for flocculation; Step 5: The high-concentration wastewater flowing out of the electro-flocculation unit enters the sedimentation tank; Step 6: The supernatant from the sedimentation tank enters the resin water treatment unit to remove heavy metal ions. Step 7: The high-concentration wastewater after being treated by the resin water treatment device 1 enters the biological contact oxidation tank for microbial degradation; Step 8: The high-concentration wastewater flowing out of the biological contact oxidation tank enters the HMF unit; Step 9: The low-concentration metal wastewater directly enters the HMF unit and is mixed with the high-concentration wastewater; the mixed wastewater is treated by membrane filtration in the HMF unit; Step 10: The mixed wastewater after being treated by the HMF unit enters the NF unit for nanofiltration membrane separation; Step 11: The produced water obtained after the NF unit treatment enters the NF unit water production pool, and the wastewater in the NF unit water production pool enters the RO unit 1 for reverse osmosis separation treatment; Step 12: The produced water obtained after being treated by RO unit 1 enters the RO unit 1 water production pool; Step 13: After the RO unit is processed to obtain concentrated water, when the sodium chloride concentration in the concentrated water is lower than the preset value, the concentrated water will be processed again in step 12; when the sodium chloride concentration in the concentrated water is not lower than the preset value, the concentrated water will enter the concentrated water tank of the RO unit; Step 14: The concentrated water obtained after the NF unit treatment enters the NF unit concentrated water tank; Step 15: The wastewater flowing out of the concentrated water tank of the NF unit enters the ozone oxidation tank; Step 16: The wastewater after being treated in the ozone oxidation tank enters the resin water processor 2 for ion exchange treatment; Step 17: The produced water obtained by the resin water treatment device 2 enters the NF unit water production pool and is mixed with the produced water obtained in step 11; Step 18: The exchange resin 2 in the resin water treatment unit 2 is eluted with HCl, and the eluted product water enters the RO unit 2. The product water obtained by the RO unit 2 treatment enters the RO unit 2 product water tank; In step 19, concentrated water is obtained after being processed by RO unit 2. When the magnesium chloride concentration in the concentrated water is lower than the preset value, the concentrated water will be processed again in step 18; when the magnesium chloride concentration in the concentrated water is not lower than the preset value, the concentrated water enters the concentrated water tank of RO unit 2.

2. The process for separating and reusing inorganic salts from metal surface treatment wastewater according to claim 1, characterized in that: In step 2, the wastewater flows out of the screen into the regulating tank by gravity or a pumping system; a stirring device is provided inside the regulating tank to stir the wastewater evenly.

3. The process for separating and reusing inorganic salts from metal surface treatment wastewater according to claim 1, characterized in that: In step three, a pH monitoring and acid-base addition system is set up in the neutralization tank, which can detect the pH value in the neutralization tank and add acid-base regulator to the neutralization tank according to the pH value.

4. The process for separating and reusing inorganic salts from metal surface treatment wastewater according to claim 1, characterized in that: In step six, the resin water treatment unit 1 is connected to the sedimentation tank via a pipeline, and a flow control device is installed on the pipeline.

5. The process for separating and reusing inorganic salts from metal surface treatment wastewater according to claim 1, characterized in that: In step seven, the resin water treatment unit 1 is connected to the biological contact oxidation tank via a pipeline, and an aeration system is provided in the biological contact oxidation tank.

6. The process for separating and reusing inorganic salts from metal surface treatment wastewater according to claim 1, characterized in that: In step nine, the low-concentration metal wastewater is directly fed into the HMF unit through a pipeline, where it is mixed with the high-concentration wastewater. In step 13 and step 19, concentration detection sensors are installed at the concentrate outlet of RO unit 1 and RO unit 2 to detect the concentration of the concentrate; and two branches are formed at the concentrate outlet, and the on-off status of the two branches is controlled by valves.

7. The process for separating and reusing inorganic salts from metal surface treatment wastewater according to claim 1, characterized in that: In step 6, the exchange resin in the resin water treatment unit 1 is a heavy metal ion adsorption resin, and the heavy metal-containing solution is obtained by elution for recycling heavy metal inorganic salts; In step 18, the exchange resin in the resin water treatment unit 2 is a magnesium ion adsorption resin, and the magnesium chloride-containing solution obtained by elution is subsequently used to reuse the magnesium chloride salt.

8. A wastewater treatment system, characterized in that: Treating wastewater using the process according to any one of claims 1 to 7; The wastewater treatment system comprises an electro-flocculation unit, wherein the electro-flocculation unit comprises a cathode tube (1), an anode core rod (2) and a buffer bin (3). The cathode tube (1) is vertically arranged and divided into a plurality of tube sections (100) distributed from top to bottom. Adjacent tube sections (100) are connected via a buffer bin (3). A tube cavity (101) is provided in the tube section (100), and a buffer inner cavity (301) is provided in the buffer bin (3). The tube cavity (101) and the buffer inner cavity (301) are interconnected to form a wastewater channel that is interconnected from top to bottom. The anode core rod (2) is coaxially arranged in the tube cavity (101) and passes through the buffer inner cavity (301); The upper end (201) of the anode core rod (2) is mounted on the upper hoisting portion (2011) to achieve hoisting limit, and the lower end (202) of the anode core rod (2) is in a hanging shape; A support assembly (5) is installed in the buffer inner cavity (301), and the support assembly (5) is used to limit the horizontal position of the anode core rod (2).

9. The wastewater treatment system according to claim 8, characterized in that: The support assembly (5) includes a support tube (51), a support block 1 (52) and a support block 2 (53); the support tube (51) is fixedly mounted on the lower side wall of the buffer inner cavity (301); the support tube (51) is provided with a gap portion (511) penetrating the inner and outer circumferences; The support block 1 (52) and the support block 2 (53) are both annular structures. The support block 1 (52) is installed on the inner periphery of the support tube (51), and the support block 2 (53) is installed on the outer periphery of the anode core rod (2). At least part of the support block 2 (53) extends into the inner periphery of the support block 1 (52) to achieve circumferential pressure limiting.

10. The wastewater treatment system according to claim 9, characterized in that: The inner circumferential surface (521) of the support block 1 (52) and the outer circumferential surface (531) of the support block 2 (53) are in an inverted conical structure that fits with each other. The inner circumferential surface (521) of the support block 1 (52) and the outer circumferential surface (531) of the support block 2 (53) are partially fitted on each other and press against each other. The outer periphery of the support block 1 (52) is adapted to slide up and down with the support cylinder (51), and a support spring (54) is installed on the lower side of the support block 1 (52), and the support spring (54) is used to apply an upward force to the support block 1 (52); The upper section of the inner periphery of the support tube (51) is fixedly connected to a limit retaining ring (512), and the limit retaining ring (512) is used to block the support block (52).

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