An on-line treatment method for chlorine dioxide generator by-products

Abstract

The application discloses a kind of chlorine dioxide generator by-product online processing method, it is related to chlorine dioxide preparation technical field, comprising: chlorine dioxide generator by-product solution and ferrous salt solution are added in by-product online processing device, in by-product online processing device, water jetor extracts mixed reactor into negative pressure, chlorine dioxide generator by-product solution is sucked into mixed reactor, and ferrous salt solution is reacted under negative pressure for 20-40 minutes to generate iron salt solution, after reaction is completed, iron salt solution is added to flocculation reaction tank for raw water purification after being sucked by water jetor;Wherein, 1.0-3.0L of 5-15% ferrous salt solution is added in every 1L chlorine dioxide generator by-product solution;The by-product after processing is used as flocculating agent, to achieve the purpose of resource utilization, processing method does not need heating, the volume of equipment used is small, investment is small, reaction speed is fast, processing efficiency is high, and operation is simple.

Description

Technical Field

[0001] This invention relates to the field of chlorine dioxide preparation technology, and more specifically to an online treatment method for byproducts of chlorine dioxide generators. Background Technology

[0002] Chlorine dioxide is an internationally recognized highly effective disinfectant and sterilizer. It can kill all microorganisms, including vegetative bacteria, bacterial spores, fungi, mycobacteria, and viruses, and these bacteria do not develop resistance. A common method for preparing chlorine dioxide involves adding sodium chlorate and acid to a reactor to react and produce chlorine dioxide. The reactor is equipped with an air inlet pipe at the inlet and a water jet injector at the outlet. The water jet injector creates negative pressure within the reactor, drawing air in through the air inlet pipe. The airflow carries out chlorine dioxide gas, which mixes with water to form a disinfectant solution. The generator produces a byproduct solution after the raw materials produce chlorine dioxide. This byproduct solution contains unreacted raw materials (such as sodium chlorate, sulfuric acid, and chlorite).

[0003] Currently, two methods are used to treat the byproducts of chlorine dioxide generators:

[0004] First, byproducts are not treated before being added directly to the water jet generator of the generator along with chlorine dioxide to form a disinfectant solution, which is then added to the tap water. This can easily cause the chlorate and chlorite levels in the tap water to exceed the standards, and the pH value of the tap water to decrease, failing to meet the requirements of the national drinking water quality standards.

[0005] Secondly, the generator is equipped with a by-product separation device (such as the Chinese patent application number 202022747908.2, entitled "A residual liquid separation device for a chlorine dioxide generator") to separate the by-product solution. For the separated by-product solution, the existing technology usually performs centralized treatment, such as the Chinese patent application number 202011329401.3, entitled "A residual liquid recovery and treatment device and method generated by a chlorine dioxide generator". It includes a concentration tank, the top of which is connected to a spray tower through a pipe. A gas burner is installed at the top of the spray tower. The bottom of the concentration tank is transported to the spray tower by a circulation pump. It also includes a residual liquid transfer pump, which transports the residual liquid generated by the chlorine dioxide generator collected in the residual liquid pool to the concentration tank. The residual liquid is concentrated by heating with gas, and solid-liquid separation is achieved. The mother liquor is recovered and returned to the chlorine dioxide generator for use. This centralized treatment method has the disadvantages of large equipment investment, high energy consumption, large footprint, and complicated operation.

[0006] To address the shortcomings of existing technologies in the treatment of byproducts from chlorine dioxide generators, we have developed a new online treatment method for byproducts from chlorine dioxide generators after years of continuous exploration and innovation. Summary of the Invention

[0007] This invention aims to address the technical problems of existing technologies for treating byproducts from chlorine dioxide generators, such as high equipment investment, high energy consumption, large footprint, and complex operation. The goal is to provide an online treatment method for byproducts from chlorine dioxide generators, enabling the online processing of these byproducts and using them as flocculants to achieve resource utilization. This method requires no heating, uses small-sized equipment, requires low investment, has a fast reaction speed, high processing efficiency, and is simple to operate.

[0008] This invention is achieved through the following technical solution:

[0009] An online treatment method for byproducts of a chlorine dioxide generator includes the following steps:

[0010] The byproduct solution from the chlorine dioxide generator and the ferrous salt solution are added to the online byproduct treatment device. Inside the online byproduct treatment device, a water jet injector creates a negative pressure in the mixing reactor, drawing the byproduct solution from the chlorine dioxide generator into the mixing reactor. The solution reacts with the ferrous salt solution under negative pressure for 20-40 minutes to generate an iron salt solution. After the reaction is complete, the iron salt solution in the mixing reactor is drawn into the flocculation reaction tank by the water jet injector for the purification of the source water. Specifically, 1.0-3.0L of 5-15% ferrous salt solution is added to every 1L of chlorine dioxide generator byproduct solution.

[0011] Furthermore, the water jet pumps the mixing reactor to a negative pressure of 50-150 kPa, and the ferrous salt solution is either a ferrous sulfate solution or a ferrous chloride solution.

[0012] Furthermore, the ferrous salt solution is metered and added to the online by-product treatment device via two separate pathways. One pathway introduces the ferrous salt solution to react with the by-product solution from the chlorine dioxide generator, while the other pathway introduces the ferrous salt solution to react with the chlorite formed by pre-oxidation.

[0013] Furthermore, the online by-product treatment device includes a shell, and inside the shell are a chlorine dioxide generator by-product feeding system, a ferrous salt solution feeding system, a mixing reactor, and a water jet injector; the mixing reactor includes a jet mixer located at the inlet end, the chlorine dioxide generator by-product feeding system and the ferrous salt solution feeding system are both connected to the inlet of the jet mixer, the outlet end of the mixing reactor is connected to the side suction port of the water jet injector, and the outlet of the water jet injector is connected to the finished product reaction liquid outlet on the shell.

[0014] Furthermore, the chlorine dioxide generator by-product feeding system includes a chlorine dioxide generator by-product inlet pipe, the inlet end of which is connected to the chlorine dioxide generator by-product inlet on the shell, and the outlet end of which is connected to the inlet of the jet mixer.

[0015] Furthermore, the ferrous salt solution feeding system includes a ferrous salt solution inlet pipe, the inlet end of which is connected to a ferrous salt solution inlet on the housing, and the outlet end of which is connected to the inlet of the jet mixer.

[0016] Furthermore, the ferrous salt solution feeding system includes a ferrous salt solution metering pump and a flow correction column installed on the pipeline. The pipeline connected to the inlet of the water jet injector, the pipeline connected to the outlet of the water jet injector, and the mixing reactor are respectively equipped with a power water pressure gauge, a dosing pipe pressure gauge, and a mixing reactor pressure gauge. The ferrous salt solution metering pump, the power water pressure gauge, the dosing pipe pressure gauge, and the mixing reactor pressure gauge are all connected to the control system.

[0017] Furthermore, the mixing reactor also includes a reaction chamber, the inlet of which is connected to the outlet of the jet mixer, and the inner wall of the reaction chamber is provided with multiple baffles.

[0018] Furthermore, the jet mixer includes a mixing chamber, a ferrous salt solution inlet, a jetting channel, and a chlorine dioxide generator by-product inlet. The ferrous salt solution inlet is connected to the mixing chamber via the jetting channel, and the chlorine dioxide generator by-product inlet is also connected to the mixing chamber.

[0019] Furthermore, the injection channel is arranged along the tangential direction of the mixing chamber, and an injection hole is provided on the mixing chamber at a position communicating with the injection channel. The injection channel is a circular channel, and its diameter gradually decreases towards the end closer to the injection hole.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] 1. This invention allows for the online addition of a corresponding ferrous salt solution based on the amount of byproducts generated by a chlorine dioxide generator. This reaction completely eliminates sodium chlorate and sodium chlorite from the byproducts and significantly consumes sulfuric acid from the chlorine dioxide generator byproducts, greatly reducing their acidity. No sodium chlorate or sodium chlorite enters the tap water, ensuring that the chlorate and chlorite levels in the water after chlorine dioxide disinfection meet standards. This achieves online treatment of byproducts generated by the chlorine dioxide generator. Simultaneously, the ferric sulfate generated from the reaction is automatically added to the front end of the tap water treatment process as a flocculant, achieving resource utilization and ensuring comprehensive utilization of the byproducts from the chlorine dioxide generator.

[0022] 2. This invention can further increase the amount of ferrous solution added based on the amount of chlorite generated during the pre-oxidation of source water, allowing the excess ferrous solution to react with the chlorite generated during the pre-oxidation of source water. This achieves the goal of removing 90% of the chlorite formed before chlorination, effectively reducing the chlorite content in the water to meet the requirements of national drinking water standards.

[0023] 3. Compared with existing technologies that rely on heating and concentration to recover mother liquor, and the equipment used, the method of this invention does not require heating, uses smaller equipment, requires less investment, has a faster reaction speed, higher processing efficiency, and is simpler to operate. The control system can automatically adjust the amount of ferrous solution added according to changes in the output of the chlorine dioxide generator, achieving the goal of precisely treating the byproducts of chlorine dioxide disinfection and enabling comprehensive utilization of these byproducts. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0025] Figure 1 This is a flowchart of Example 1;

[0026] Figure 2 This is a flowchart illustrating Example 2;

[0027] Figure 3 This is a schematic diagram of the online by-product processing device;

[0028] Figure 4 This is a schematic diagram of the structure of a mixing reactor;

[0029] Figure 5 This is a schematic diagram of the jet mixer.

[0030] Figure 6 This is a cross-sectional view of the internal structure of the jet mixer.

[0031] The attached diagram shows the markings and corresponding component names:

[0032] 1-Shell, 101-Power water inlet, 102-Finished reaction solution outlet, 103-Chlorine dioxide generator by-product inlet, 104-Ferrous salt solution inlet, 2-Control system, 3-Power water pressure gauge, 4-Dosing pipe pressure gauge, 5-Water jet injector, 6-Power water pipe, 7-Dosing pipe, 8-Mixing reactor pressure gauge, 9-Mixing reactor, 901-Shell, 902-Jet mixer, 9021-Mixing chamber, 9022-Ferrous salt solution inlet, 9023-Jet channel, 9024-Chlorine dioxide generator by-product inlet, 9025-Jet hole, 903-Reaction chamber, 904-Baffle plate, 905-Reaction solution outlet, 10-Chlorine dioxide generator by-product inlet pipe, 11-Ferrous salt solution inlet pipe, 12-Ferrous salt solution metering pump, 13-Flow calibration column. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0034] In this invention, pre-chlorination refers to the pre-oxidation of source water using chlorine dioxide disinfectant prepared by a chlorine dioxide generator, while post-chlorination refers to the disinfection of tap water using chlorine dioxide disinfectant prepared by a chlorine dioxide generator after flocculation.

[0035] The byproduct solution of the chlorine dioxide generator refers to the residual liquid produced by the chlorine dioxide generator. In the prior art, the residual liquid is usually treated centrally, that is, by heating and concentrating the residual liquid, separating the solid and liquid, and recovering the mother liquor for use in the chlorine dioxide generator. This centralized treatment method has the disadvantages of large equipment investment, high energy consumption, large footprint, and complicated operation.

[0036] There is currently no method or device for directly adding ferrous iron to treat chlorine dioxide generator byproducts online based on changes in the amount of byproducts. Based on the shortcomings of existing technologies in the treatment of chlorine dioxide generator byproducts, the inventors have developed a new online treatment method for chlorine dioxide generator byproducts after years of continuous exploration and innovation. The method is equipped with a dedicated online treatment device, which realizes the online treatment of chlorine dioxide generator byproducts. The treatment does not require heating, has low energy consumption, small equipment size, small footprint, and low investment cost.

[0037] This invention provides an online treatment method for byproducts of a chlorine dioxide generator, comprising the following steps:

[0038] The byproduct solution from the chlorine dioxide generator and the ferrous salt solution are added to the online byproduct treatment device. Inside the online byproduct treatment device, the water jet injector 5 draws the mixing reactor 9 into negative pressure, causing the byproduct solution from the chlorine dioxide generator to be drawn into the mixing reactor 9. The solution reacts with the ferrous salt solution under negative pressure for 20-40 minutes to generate an iron salt solution. After the reaction is completed, the iron salt solution in the mixing reactor 9 is drawn into the flocculation reaction tank by the water jet injector 5 for the purification of the source water. Among them, 1.0-3.0L of 5-15% ferrous salt solution is added to every 1L of chlorine dioxide generator byproduct solution.

[0039] Specifically, the water jet 5 draws the mixing reactor 9 to a negative pressure of 50-150 kPa, and the ferrous salt solution is either a ferrous sulfate solution or a ferrous chloride solution.

[0040] Specifically, the ferrous salt solution is metered and added to the online by-product treatment device via two separate paths. One path introduces the ferrous salt solution to react with the by-product solution from the chlorine dioxide generator, while the other path introduces the ferrous salt solution to react with the chlorite formed by pre-oxidation.

[0041] Among them, reference Figure 3-6 As shown, the online by-product treatment device includes a shell 1, a chlorine dioxide generator by-product feeding system, a ferrous salt solution feeding system, a mixing reactor 9, and a water jet injector 5 disposed inside the shell 1; the mixing reactor 9 includes a jet mixer 902 disposed at the inlet end, the chlorine dioxide generator by-product feeding system and the ferrous salt solution feeding system are both connected to the inlet of the jet mixer 902, the outlet end of the mixing reactor 9 is connected to the side suction port of the water jet injector 5, and the outlet of the water jet injector 5 is connected to the finished product reaction liquid outlet 102 on the shell 1.

[0042] When using the online by-product treatment device, first turn on the power to the control system 2, set the various control parameters of the control system 2, open the valves on the inlet and outlet connecting pipes of the water jet injector 5, and draw the mixing reactor 9 into a negative pressure of 50-150 kPa to facilitate the suction of the by-products from the chlorine dioxide generator into the mixing reactor 9. The chlorine dioxide generator by-product feeding system and the ferrous salt solution feeding system feed the generator by-products and ferrous salt solution respectively. Open the valves on the ferrous salt solution inlet pipe 11 and the chlorine dioxide generator by-product inlet pipe 10. When the chlorine dioxide generator is running, it will send operating signals. The signal is transmitted to the control system 2. The control system 2 sends the operating signal to the ferrous salt solution metering pump 12 according to the operating load of the generator. The ferrous salt solution metering pump 12 pumps the required ferrous solution into the jet mixer 902 at the inlet end of the mixing reactor 9. It is fully mixed with the by-product solution from the chlorine dioxide generator through the jet mixer 902, and then enters the mixing reactor 9 to react and generate a ferric salt solution. The ferric salt solution enters the water jet injector 5 from the outlet end of the mixing reactor 9, and flows out through the dosing pipe 7 connected to the water jet injector 5. It can be added to the flocculant dosing point of the waterworks for the purification of the source water.

[0043] By using this online byproduct treatment device, the treatment of byproducts from the chlorine dioxide generator can be achieved without heating, with small equipment size, low investment, fast reaction speed, higher processing efficiency, and simpler operation. Control system 2 can automatically adjust the amount of ferrous solution added according to changes in the chlorine dioxide generator's output, achieving precise treatment of chlorine dioxide disinfection byproducts and enabling comprehensive utilization of these byproducts.

[0044] Furthermore, the chlorine dioxide generator by-product feeding system includes a chlorine dioxide generator by-product inlet pipe 10. The inlet end of the chlorine dioxide generator by-product inlet pipe 10 is connected to the chlorine dioxide generator by-product inlet 103 on the shell 1, and the outlet end of the chlorine dioxide generator by-product inlet pipe 10 is connected to the inlet of the jet mixer 902. Through the chlorine dioxide generator by-product inlet pipe 10, the by-product of the chlorine dioxide generator can be passed into the mixing reactor 9 and mixed with the ferrous salt solution. The reaction directly generates ferric salt (ferric sulfate or ferric chloride), which is added to the front end of the tap water supply for water purification.

[0045] Furthermore, the ferrous salt solution feeding system includes a ferrous salt solution inlet pipe 11. The inlet end of the ferrous salt solution inlet pipe 11 is connected to the ferrous salt solution inlet 104 on the shell 1, and the outlet end of the ferrous salt solution inlet pipe 11 is connected to the inlet of the jet mixer 902. The ferrous salt solution can be introduced into the mixing reactor 9 through the ferrous salt solution inlet pipe 11 to mix with the by-product solution of the chlorine dioxide generator. Unreacted raw materials such as sodium chlorate and sulfuric acid in the by-products are reacted directly with ferrous salts to generate trivalent ferric salts (ferric sulfate or ferric chloride), which are then added to the front end of the tap water supply for water purification.

[0046] Furthermore, the ferrous salt solution feeding system includes a ferrous salt solution metering pump 12 and a flow correction column 13 installed on the pipeline. The pipeline connected to the inlet of the water ejector 5, the pipeline connected to the outlet of the water ejector 5, and the mixing reactor 9 are respectively equipped with a dynamic water pressure gauge 3, a pressure gauge 4 on the dosing pipe 7, and a pressure gauge 8 on the mixing reactor 9. The ferrous salt solution metering pump 12, the dynamic water pressure gauge 3, the pressure gauge 4 on the dosing pipe 7, and the pressure gauge 8 on the mixing reactor 9 are all connected to the control system 2. The control system 2 enables automatic control of the pipeline pressure and automatic metering and control of the ferrous salt solution dosage.

[0047] Furthermore, the mixing reactor 9 also includes a reaction chamber 903, which is located inside the outer shell 901. The inlet of the reaction chamber 903 is connected to the outlet of the jet mixer 902, and the inner wall of the reaction chamber 903 is provided with multiple baffles 904. The by-product solution of the chlorine dioxide generator and the ferrous salt solution are rapidly and thoroughly mixed in the jet mixer 902, and then enter the reaction chamber 903 of the mixing reactor 9 for further reaction. The mixture then flows out from the reaction liquid outlet 905 of the mixing reactor 9 and is added to the flocculant dosing point of the waterworks via the water jet injector 5 for the purification of the source water. By adding baffles 904 to the mixing reactor 9, the flow direction of the reaction liquid can be controlled. After passing through the baffles 904 at each stage, the reaction liquid flows out from the reaction liquid outlet 905. This can prevent short circuit of the reaction liquid, increase the reaction time of the reaction liquid, and also increase the mixing effect to ensure a full reaction. The number of baffles 904 is preferably 3-10, more preferably 6.

[0048] Further, the jet mixer 902 includes a mixing chamber 9021, a ferrous salt solution inlet 9022, a jetting channel 9023, and a chlorine dioxide generator by-product inlet 9024. The ferrous salt solution inlet 9022 is connected to the mixing chamber 9021 via the jetting channel 9023, and the chlorine dioxide generator by-product inlet 9024 is also connected to the mixing chamber 9021. The jet mixer 902 is fixed to the outer shell 901 of the mixing reactor 9 by welding or bonding. The ferrous salt solution enters the jetting channel 9023 from the ferrous salt solution inlet 9022 and is jetted into the mixing chamber 9021, where it strongly impacts and thoroughly mixes with the generator by-product solution entering from the chlorine dioxide generator by-product inlet 9024. The mixed reaction liquid flows out of the mixing chamber 9021 and into the reaction chamber 903, flows through various baffles 904, and flows out after sufficient reaction.

[0049] Furthermore, the injection channel 9023 is arranged tangentially to the mixing chamber 9021. An injection hole 9025 is provided on the mixing chamber 9021 at a position communicating with the injection channel 9023. The injection channel 9023 is a circular channel, with its diameter gradually decreasing towards the end near the injection hole 9025. The ferrous salt solution enters the injection channel 9023 through the ferrous salt solution inlet 9022 and is injected tangentially into the injection mixer 902 through the injection hole, rapidly mixing with the by-product solution of the chlorine dioxide generator. This increases the reaction rate. Simultaneously, the injected ferrous salt solution strongly impacts the by-product solution of the chlorine dioxide generator, enhancing the mixing effect and ensuring a complete reaction. By arranging the injection channel 9023 tangentially to the mixing chamber 9021, the ferrous salt solution can be injected tangentially, increasing the injection speed. Furthermore, designing the injection channel 9023 with its diameter gradually decreasing towards the end near the injection hole 9025 further increases the injection speed and improves the mixing effect.

[0050] Both the mixing reactor 9 and the jet mixer 902 are made of corrosion-resistant CPVC or PVC material. Specifically, they can be made of PVC or CPVC pipe with a diameter of Φ110-250mm and a length of 600mm-1200mm. The outer diameter of the jet mixer 902 matches the inner diameter of the mixing reactor 9. The jet hole 9025 on the jet mixer 902 that communicates with the jet channel 9023 has a diameter of Φ2mm-Φ6mm. The corrosion-resistant CPVC or PVC material can well meet the corrosive requirements of the reaction medium.

[0051] In addition, it should be noted that for flocculation reaction tanks within 50m of chlorine dioxide generators, the water jet injector 5 of the online by-product treatment device should be installed inside the online by-product treatment device to reduce on-site installation; for sites with a distance greater than 50m, the water jet injector 5 can be installed on the flocculation reaction tank to ensure that the negative pressure of the treatment device meets the reaction requirements and that the by-products of the chlorine dioxide generator can be automatically drawn into the online by-product treatment device.

[0052] The treatment method of the present invention will be further explained below using different water quality from different water plants as examples.

[0053] Example 1

[0054] This embodiment uses a 50,000 T / d water plant as an example to provide a specific implementation case of an online treatment method for byproducts of a chlorine dioxide generator. The disinfection byproduct separation device adopts the Chinese patent application number 202022747908.2 of this company, and the chlorine dioxide generator can adopt the Chinese patent application number 201811238534.2 of this company, or other existing chlorine dioxide generators. The structure and model of the chlorine dioxide generator do not affect the implementation of this invention.

[0055] A 50,000 T / d water plant with relatively good source water quality is equipped with a chlorine dioxide generator with an automatic disinfection byproduct separation device and a maximum load of 2 kg / h for drinking water disinfection. The disinfection byproducts need to be treated. Currently, the operating load is 1.5 kg / h, and the chlorine dioxide generator produces 12 L / h of byproducts. The byproducts contain 4.5% NaClO3, 16.5% H2SO4, and 12% ClO2. - The content of Na2SO4 is 12.3%, and the pH value is less than 1.0.

[0056] The byproducts of the chlorine dioxide generator are discharged from the residual liquid discharge pipe. The water jet in the online byproduct treatment device draws the mixing reactor to a negative pressure of 50-150 kPa, so that the byproduct solution of the chlorine dioxide generator is drawn into the mixing reactor of the online byproduct treatment device. According to the operating load of the chlorine dioxide generator, the control system calculates that 10% FeSO4 solution should be added at a rate of 18 L / h. The reaction in the mixing reactor is carried out for 30 minutes to generate ferric sulfate. The generated ferric sulfate is drawn into the flocculation reaction tank of the water plant after being drawn into the water jet for the purification of the source water.

[0057] The chlorate content in the water at the downstream end of the flocculation reaction tank was 0.03 mg / L, the chlorite content was 0.02 mg / L, and the pH value was 8.0 (the pH value of the source water was 8.05). The chlorate content in the treated water was 0.11 mg / L, the chlorite content was 0.21 mg / L, and the pH value was 8.03.

[0058] In this embodiment, a corresponding ferrous salt solution is added online according to the amount of byproducts generated by the chlorine dioxide generator to react completely with the sodium chlorate and sodium chlorite in the byproducts. This process also consumes a large amount of sulfuric acid in the byproducts of the chlorine dioxide generator, greatly reducing the acidity of the byproducts and preventing sodium chlorate and sodium chlorite from entering the tap water. This ensures that the chlorate and chlorite levels in the water are within acceptable limits after chlorine dioxide disinfection. At the same time, the ferric sulfate generated in the reaction is automatically added to the front end of the tap water treatment process as a flocculant, achieving the goal of resource utilization and comprehensively utilizing the byproducts of the chlorine dioxide generator.

[0059] Using the treatment method of this invention, all the ferric sulfate produced in the reaction is added to the flocculation reaction tank as a flocculant. Based on a daily water treatment volume of 50,000 tons / day and an addition of 25g of polyaluminum chloride per ton of water, the required amount of polyaluminum chloride is 1250kg. Now, by adding the ferric sulfate produced as a byproduct of the reaction, the amount of polyaluminum chloride used can be reduced to 20g / ton of water to meet the purification requirements. This translates to a reduction of 250kg of polyaluminum chloride per day. With a purchase price of 2600 yuan / ton for polyaluminum chloride, this reduces the cost by 650 yuan / day. Since 18L / h of 10% ferrous sulfate is added per hour, which is equivalent to 51.8kg of solid ferrous sulfate, and with a purchase price of 800 yuan / ton, the required cost is 41.5 yuan / day. Therefore, the daily cost reduction is 608.5 yuan, resulting in a monthly cost reduction of 18255 yuan.

[0060] In addition, existing technologies typically use heating and concentration to recover the mother liquor to treat the by-product solution. For example, the heating and concentration equipment involved in Chinese patent application No. 202011329401.3, entitled "A device and method for recovering and treating residual liquid generated by a chlorine dioxide generator", has a large energy consumption. The comparison data of the present invention with this method in terms of equipment investment and energy consumption is shown in Table 1.

[0061] Table 1. Comparison of investment and energy consumption between the equipment of the present invention and the original concentration and heating equipment.

[0062]

[0063] As can be seen from the comparison in Table 1, compared with the existing technology that uses heating to concentrate and recover the mother liquor, the present invention does not require heating for the treatment of by-products from chlorine dioxide generators. It also features smaller equipment size, lower investment, faster reaction speed, higher processing efficiency, and simpler operation. The control system can automatically adjust the amount of ferrous solution added based on changes in the output of the chlorine dioxide generator, achieving the goal of precisely treating the by-products of chlorine dioxide disinfection and enabling comprehensive utilization of these by-products.

[0064] Example 2

[0065] This embodiment uses a 40,000 T / d water plant as an example to provide a specific implementation case of an online treatment method for byproducts of a chlorine dioxide generator. The disinfection byproduct separation device adopts the Chinese patent application number 202022747908.2 of this company. The chlorine dioxide generator can adopt the Chinese patent application number 201811238534.2 of this company, or other existing chlorine dioxide generators. The structure and model of the chlorine dioxide generator do not affect the implementation of this invention.

[0066] The equipment and operating methods used in this embodiment are the same as those in Embodiment 1. The difference is that the source water quality is poor, so two chlorine dioxide generators with automatic separation devices for disinfection byproducts are configured with a maximum load of 2 kg / h. One generator is used for pre-oxidation (pre-chlorination), and the other is used for drinking water disinfection (post-chlorination). The current operating load is 1.5 kg / h for pre-chlorination and 1 kg / h for post-chlorination. The total amount of byproducts produced by the two chlorine dioxide generators is 20 L / h.

[0067] Testing revealed that the amount of chlorite formed after pre-oxidation of the source water was 0.32 mg / L. Therefore, in addition to treating the byproducts of the chlorine dioxide generator, it is also necessary to treat the disinfection byproducts (chlorite) formed during pre-oxidation: FeSO4 solution enters the mixing reactor through two paths. One path involves adding 30 L / h of 10% FeSO4 solution based on the operating load of the chlorine dioxide generator, calculated by the control system, to react and generate ferric sulfate. The other path involves introducing 34.5 L / h of 10% FeSO4 solution to react with the chlorite formed during pre-oxidation in the water.

[0068] The chlorate content in the water at the downstream end of the flocculation reaction tank was 0.05 mg / L, the chlorite content was 0.08 mg / L, and the pH value was 7.9 (the pH value of the source water was 8.05). The chlorate content in the treated water was 0.13 mg / h and the chlorite content was 0.27 mg / L.

[0069] This embodiment sets up two ferrous salt solution addition paths. One path adds the corresponding ferrous salt solution online based on the amount of byproducts generated by the chlorine dioxide generator, reacting the sodium chlorate and sodium chlorite in the byproducts and consuming a large amount of sulfuric acid in the chlorine dioxide generator byproducts, greatly reducing the acidity of the generator byproducts. This prevents sodium chlorate and sodium chlorite from entering the tap water, ensuring that the chlorate and chlorite levels in the water after chlorine dioxide disinfection meet the standards. At the same time, the ferric sulfate generated in the reaction is automatically added to the front end of the tap water treatment process as a flocculant, achieving the purpose of resource utilization and comprehensively utilizing the byproducts of the chlorine dioxide generator. The other path increases the amount of ferrous solution added based on the amount of chlorite generated by the pre-oxidation of the source water, allowing the excess ferrous solution to react with the chlorite generated by the pre-oxidation of the source water, achieving the goal of removing 90% of the chlorite formed before chlorination, making the chlorite content of the effluent below 0.3 mg / L, effectively reducing the chlorite content in the water and meeting the requirements of national drinking water standards.

[0070] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for online treatment of byproducts from a chlorine dioxide generator, characterized in that, Includes the following steps: The byproduct solution of the chlorine dioxide generator and the ferrous salt solution are added to the online byproduct treatment device. In the online byproduct treatment device, the water jet (5) draws the mixing reactor (9) into negative pressure, so that the byproduct solution of the chlorine dioxide generator is drawn into the mixing reactor (9) and reacts with the ferrous salt solution under negative pressure for 20-40 minutes to generate an iron salt solution. After the reaction is completed, the iron salt solution in the mixing reactor (9) is drawn into the flocculation reaction tank by the water jet (5) for the purification of the source water. Among them, 1.0-4.0 L of 5-15% ferrous salt solution is added to every 1L of chlorine dioxide generator byproduct solution. The online by-product processing device includes a shell (1), a chlorine dioxide generator by-product feeding system, a ferrous salt solution feeding system, a mixing reactor (9), and a water jet (5) disposed inside the shell (1); the mixing reactor (9) includes a jet mixer (902) disposed at the inlet end, the chlorine dioxide generator by-product feeding system and the ferrous salt solution feeding system are both connected to the inlet of the jet mixer (902), the outlet end of the mixing reactor (9) is connected to the side suction port of the water jet (5), and the outlet of the water jet (5) is connected to the finished product reaction liquid outlet (102) on the shell; The mixing reactor (9) further includes a reaction chamber (903), the inlet of which is connected to the outlet of the jet mixer (902), and the inner wall of the reaction chamber (903) is provided with a plurality of baffles (904); The jet mixer (902) includes a mixing chamber (9021), a ferrous salt solution inlet (9022), a jetting channel (9023), and a chlorine dioxide generator by-product inlet (9024). The ferrous salt solution inlet (9022) is connected to the mixing chamber (9021) through the jetting channel (9023), and the chlorine dioxide generator by-product inlet (9024) is connected to the mixing chamber (9021). The injection channel (9023) is arranged along the tangential direction of the mixing chamber (9021). An injection hole (9025) is provided on the mixing chamber (9021) at a position communicating with the injection channel (9023). The injection channel (9023) is a circular channel, and its diameter gradually decreases towards the end closer to the injection hole (9025).

2. The method for online treatment of byproducts from a chlorine dioxide generator according to claim 1, characterized in that, The water jet (5) pumps the mixing reactor (9) to a negative pressure of 50-150 kPa, and the ferrous salt solution is either ferrous sulfate solution or ferrous chloride solution.

3. The method for online treatment of byproducts from a chlorine dioxide generator according to claim 1, characterized in that, The ferrous salt solution is metered and added to the online by-product treatment device via two separate pathways. One pathway introduces the ferrous salt solution to react with the by-product solution from the chlorine dioxide generator, while the other pathway introduces the ferrous salt solution to react with the chlorite formed by pre-oxidation.

4. The method for online treatment of byproducts from a chlorine dioxide generator according to claim 1, characterized in that, The chlorine dioxide generator by-product feeding system includes a chlorine dioxide generator by-product inlet pipe (10), the inlet end of which is connected to the chlorine dioxide generator by-product inlet (103) on the shell (1), and the outlet end of which is connected to the inlet of the jet mixer (902).

5. The method for online treatment of byproducts from a chlorine dioxide generator according to claim 1, characterized in that, The ferrous salt solution feeding system includes a ferrous salt solution inlet pipe (11), the inlet end of which is connected to the ferrous salt solution inlet (104) on the housing (1), and the outlet end of which is connected to the inlet of the jet mixer (902).

6. The method for online treatment of byproducts from a chlorine dioxide generator according to claim 1, characterized in that, The ferrous salt solution feeding system includes a ferrous salt solution metering pump (12) and a flow correction column (13) installed on the pipeline. The pipeline connected to the inlet of the water jet (5), the pipeline connected to the outlet of the water jet (5), and the mixing reactor (9) are respectively equipped with a power water pressure gauge (3), a dosing pipe pressure gauge (4), and a mixing reactor pressure gauge (8). The ferrous salt solution metering pump (12), the power water pressure gauge (3), the dosing pipe pressure gauge (4), and the mixing reactor pressure gauge (8) are all connected to the control system (2).

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