Method and system for treating high-chlorine high-organic-matter wastewater

Abstract

The invention provides a treatment method and system for high-chlorine high-organic-matter wastewater, and the treatment method comprises the following steps: firstly, carrying out ozone micro-nano bubble oxidation treatment on the high-chlorine high-organic-matter wastewater to obtain first effluent; then the first effluent is conveyed to a buffer pool and stays for a preset staying duration, and second effluent is obtained; the second outlet water is heated to be within the preset temperature range, and third outlet water is obtained; and finally, conveying the third effluent to a filtering tower filled with a modified steel slag filtering medium for filtering treatment to obtain fourth effluent. According to the treatment method and system for the high-chlorine and high-organic-matter wastewater, the problem that the concentration of residual ozone is too high due to addition of high-concentration ozone can be solved, and it can be ensured that the ORP value of final effluent meets the water inlet requirements of a subsequent reverse osmosis membrane process and a nanofiltration membrane process; therefore, the normal operation of the multi-stage membrane concentration salt separation system can be ensured.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a method and system for treating high-chlorine, high-organic-content wastewater. Background Technology

[0002] In recent years, membrane concentration technology has been frequently used in the field of industrial wastewater treatment, particularly in advanced wastewater treatment and zero-discharge processes. While this technology enables water resource recovery and reuse, it also leads to the continuous enrichment of organic matter in wastewater, resulting in high-concentration organic wastewater. This type of high-concentration organic wastewater contains a large amount of recalcitrant organic matter, posing significant hazards in advanced wastewater treatment and zero-discharge systems. For example, it can cause fouling of membrane modules at the downstream end of the system, reducing membrane performance and lifespan. Therefore, effective treatment of this type of high-concentration organic wastewater is essential. Advanced oxidation processes, which generate highly oxidizing hydroxyl radicals, have become a primary method for treating this type of wastewater. Among these, ozone oxidation has attracted considerable attention due to its advantages of effectively destroying the unsaturated structure of pollutants and producing no secondary pollution.

[0003] In traditional ozone catalytic oxidation processes, the ozone concentration typically needs to be dynamically adjusted based on water quality, treatment objectives, and process conditions. In cases treating chemical, dyeing, and coking wastewater, the typical ozone concentration range is 20 mg / L to 100 mg / L, and the oxidized wastewater exhibits improved biodegradability, making it suitable as influent for further biological treatment. Currently, the COD concentration in high-salt, high-organic wastewater generated from advanced wastewater treatment and zero-discharge processes is typically between 200 mg / L and 500 mg / L. When using traditional ozone catalytic oxidation processes, to effectively degrade the high concentration of organic matter in the wastewater, the added ozone concentration generally needs to be greater than 100 mg / L, and even reach 300 mg / L.

[0004] However, while this approach effectively degrades high concentrations of organic matter in wastewater, it also leads to high residual ozone concentrations. This can easily cause oxidation of subsequent reverse osmosis and nanofiltration membranes, resulting in the failure of the multi-stage membrane concentration and desalination system. Especially in high-chlorine, high-organic-matter wastewater with chloride ion content greater than 2000 mg / L, the COD concentration is generally greater than 100 mg / L. When using traditional ozone catalytic oxidation processes, the ozone concentration needs to be greater than 50 mg / L to effectively degrade the high concentrations of organic matter in the wastewater. However, this results in a residual ozone concentration in the high-chlorine, high-organic-matter wastewater greater than 0.1 mg / L, leading to an ORP value greater than 200 mV. Since the feed water requirements for reverse osmosis and nanofiltration processes are an ORP value less than 200 mV, this will negatively impact the subsequent reverse osmosis and nanofiltration processes. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for treating high-chlorine and high-organic-content wastewater, in order to solve one or more of the problems existing in the prior art, such as the addition of high-concentration ozone in order to effectively degrade the high concentration of organic matter in high-chlorine and high-organic-content wastewater, resulting in a high concentration of residual ozone, which easily causes oxidation of subsequent reverse osmosis membranes and nanofiltration membranes, and failure of multi-stage membrane concentration and desalination systems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for treating high-chlorine, high-organic-content wastewater, comprising: The high-chlorine, high-organic-content wastewater was subjected to ozone micro-nano bubble oxidation treatment to obtain the first effluent. The first effluent is transported to a buffer tank and left to stand for a preset duration to obtain the second effluent; The second outlet water is heated to a preset temperature range to obtain the third outlet water; The third effluent is transported to a filter tower filled with modified steel slag filter media for filtration treatment to obtain the fourth effluent.

[0007] Optionally, the step of treating the high-chlorine, high-organic-content wastewater with ozone micro-nano bubble oxidation to obtain the first effluent includes: transporting the high-chlorine, high-organic-content wastewater to an ozone contact tank; and transporting ozone gas in the form of micro-nano bubbles to the ozone contact tank so that the high-chlorine, high-organic-content wastewater and the ozone gas undergo an ozone catalytic oxidation reaction to obtain the first effluent.

[0008] Optionally, the preset stay duration can range from 1.5 hours to 4 hours.

[0009] Optionally, heating the second effluent to a preset temperature range to obtain the third effluent includes: conveying the second effluent to a heat exchanger and supplying a heat source to the heat exchanger so that the second effluent is heated to a preset temperature range of 30 degrees Celsius to 65 degrees Celsius to obtain the third effluent.

[0010] Optionally, the modified steel slag filter medium is prepared from steel slag raw materials, dilute sulfuric acid solution, dilute manganese sulfate solution, and sodium carbonate powder. The steel slag raw materials, by mass percentage, have a total FeO and Fe2O3 content of 5%–20% and a SiO2 content of 7%–12%. The modified steel slag filter medium is prepared through the following steps: ball milling the steel slag raw materials, sieving them using a multi-stage standard sieve between 5 and 40 mesh, and classifying them according to the mesh size of the standard sieve used, collecting the steel slag particles corresponding to each mesh size range; immersing each grade of steel slag particles in a dilute manganese sulfate solution with a concentration of 0.2 mg / L–3.5 mg / L, and allowing them to stand. The mixture is placed in a heating device and heated to 850°C–950°C at a rate of 1°C / min–10°C / min, and then held for 20 minutes–85 minutes to obtain quenched steel slag. The quenched steel slag is cooled to room temperature and then immersed in a dilute sulfuric acid solution with a pH of 4–6. The dilute sulfuric acid solution is heated to 40°C–70°C and held for 1 hour–4 hours. The quenched steel slag is then removed, rinsed with water 3–5 times, and then dried to obtain the modified steel slag filter medium.

[0011] To achieve the above objectives, the present invention also provides a treatment system for high-chlorine, high-organic-content wastewater, comprising an ozone oxidation unit, a buffer treatment unit, a heating treatment unit, and a filtration unit arranged sequentially; the ozone oxidation unit is configured to perform ozone micro-nano bubble oxidation treatment on the high-chlorine, high-organic-content wastewater to obtain a first effluent; the buffer treatment unit is configured to transport the first effluent to a buffer tank and retain it for a preset residence time to obtain a second effluent; the heating treatment unit is configured to heat the second effluent to a preset temperature range to obtain a third effluent; the filtration unit is configured to transport the third effluent to a filter tower filled with modified steel slag filter media for filtration treatment to obtain a fourth effluent.

[0012] Optionally, the ozone oxidation unit includes a first inlet pump and an ozone contact tank arranged sequentially. A micro / nano bubble generator is connected to the ozone contact tank, and an ozone generator is connected to the micro / nano bubble generator. The first inlet pump is configured to: transport the high-chlorine, high-organic-content wastewater to the ozone contact tank. The ozone generator is configured to: supply ozone gas to the micro / nano bubble generator. The micro / nano bubble generator is configured to: transport the received ozone gas to the ozone contact tank in the form of micro / nano bubbles. The ozone contact tank is configured to: allow the high-chlorine, high-organic-content wastewater to undergo an ozone catalytic oxidation reaction with the ozone gas to obtain the first effluent.

[0013] Optionally, the buffer processing unit includes a second inlet pump and a buffer tank arranged in sequence; the second inlet pump is configured to: deliver the first effluent to the buffer tank; the buffer tank is configured to: receive the first effluent and allow it to remain for a preset duration to obtain the second effluent.

[0014] Optionally, the heating treatment unit includes a third inlet pump and a heat exchanger arranged in sequence; the third inlet pump is configured to deliver the second outlet water to the heat exchanger; the heat exchanger is configured to heat the second outlet water to a preset temperature range to obtain the third outlet water.

[0015] Optionally, the filtration unit includes a fourth inlet pump and the filter tower arranged sequentially; the fourth inlet pump is configured to deliver the third effluent to the filter tower; the filter tower is configured to filter the third effluent using the modified steel slag filter medium to obtain the fourth effluent.

[0016] Compared with existing technologies, the method and system for treating high-chlorine and high-organic-content wastewater provided by this invention have the following beneficial effects: The present invention provides a method for treating high-chloride, high-organic-content wastewater. First, the wastewater is subjected to ozone micro-nano bubble oxidation treatment to obtain a first effluent. By employing ozone micro-nano bubble technology, the concentration and mass transfer efficiency of ozone in the wastewater can be significantly improved. Compared with traditional ozone catalytic oxidation processes, ozone micro-nano bubble technology requires no catalyst, avoiding catalytic deactivation caused by high concentrations of chloride ions, and possesses excellent mass transfer performance and free radical generation capacity, thus effectively degrading high concentrations of organic matter in the high-chloride, high-organic-content wastewater. Then, the first effluent is transported to a buffer tank and held for a preset residence time to obtain a second effluent. The buffer tank, by containing the first effluent obtained after ozone micro-nano bubble oxidation treatment and holding it for the preset residence time, allows residual ozone in the wastewater to decay. Next, the second effluent is heated to a preset temperature range to obtain a third effluent. This heating treatment accelerates the decay of residual ozone and improves the catalytic decomposition effect of the subsequent filtration tower on residual ozone in the wastewater. Finally, the third effluent is sent to a filter tower filled with modified steel slag filter media for filtration, yielding the fourth effluent. The modified steel slag filter media catalytically decomposes residual ozone in the wastewater, thereby reducing its concentration. The treatment method for high-chlorine, high-organic-content wastewater provided by this invention not only solves the problem of excessively high residual ozone concentrations caused by high-concentration ozone addition, but also ensures that the final effluent's ORP value meets the feed water requirements of subsequent reverse osmosis and nanofiltration membrane processes, thus guaranteeing the normal operation of the multi-stage membrane concentration and desalination system.

[0017] Since the high-chlorine, high-organic-content wastewater treatment system provided by this invention and the high-chlorine, high-organic-content wastewater treatment method provided by this invention belong to the same inventive concept, the high-chlorine, high-organic-content wastewater treatment system provided by this invention has at least all the advantages of the high-chlorine, high-organic-content wastewater treatment method provided by this invention. For the advantages of the high-chlorine, high-organic-content wastewater treatment system provided by this invention, please refer to the relevant description of the beneficial effects of the high-chlorine, high-organic-content wastewater treatment method provided by this invention, which will not be repeated here. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall steps of a method for treating high-chlorine, high-organic-content wastewater according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of a specific process for treating high-chlorine, high-organic-content wastewater according to Embodiment 1 of the present invention; Figure 3 This is a structural block diagram of a high-chlorine, high-organic-content wastewater treatment system provided in Embodiment 2 of the present invention; Figure 4 This is a process flow diagram of a high-chlorine, high-organic-content wastewater treatment system provided in Embodiment 2 of the present invention; The annotations in the attached figures are explained as follows: 1-Ozone oxidation unit, 11-First inlet pump, 12-Ozone contact tank, 13-Micro-nano bubble generator, 14-Ozone generator; 2-Buffer processing unit, 21-Second inlet pump, 22-Buffer pool; 3-Heating treatment unit, 31-Third water inlet pump, 32-Heat exchanger; 4-Filter unit, 41-Fourth inlet pump, 42-Filter tower. Detailed Implementation

[0019] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the treatment method and system for high-chlorine, high-organic-content wastewater proposed in this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, used only to facilitate and clarify the illustration of the embodiments of this invention. Please refer to the accompanying drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this invention. Any modifications to the structure, changes in proportions, or adjustments to the size, provided that the effects and objectives achieved by this invention are the same or similar, should still fall within the scope of the technical content disclosed in this invention. Specific design features of the invention disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the specific application and usage environment. Furthermore, in the embodiments described below, the same reference numerals are sometimes used across different drawings to denote the same parts or parts having the same function, omitting repeated descriptions.

[0020] It should be understood that, unless specifically stated or obvious from the context, as used herein, the term “about” is understood to mean within the normal tolerance range in the field, such as within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise specified from the context, all numerical values ​​provided herein are modified by the term “about”.

[0021] Example 1 This embodiment provides a method for treating wastewater with high chlorine and high organic content. For details, please refer to [link to relevant documentation]. Figure 1 and Figure 2 , Figure 1 This is a schematic diagram illustrating the overall steps of the treatment method for high-chlorine and high-organic-content wastewater provided in this embodiment; Figure 2 This is a schematic diagram illustrating the specific process of the treatment method for high-chlorine, high-organic-content wastewater provided in this embodiment. From... Figure 1 and Figure 2 As can be seen, the processing method includes: S100: The high-chlorine, high-organic-content wastewater is subjected to ozone micro-nano bubble oxidation treatment to obtain the first effluent; S200: The first effluent is transported to the buffer tank 22 and left for a preset residence time to obtain the second effluent; S300: Heat the second outlet water to a preset temperature range to obtain the third outlet water; S400: The third effluent is transported to a filter tower 42 filled with modified steel slag filter media for filtration treatment to obtain the fourth effluent.

[0022] Therefore, the treatment method for high-chlorine and high-organic-content wastewater provided in this embodiment first treats the wastewater with ozone micro-nano bubble oxidation to obtain a first effluent. By employing ozone micro-nano bubble technology, the concentration and mass transfer efficiency of ozone in the wastewater can be significantly improved. Compared with traditional ozone catalytic oxidation processes, ozone micro-nano bubble technology does not require a catalyst, avoids the catalytic deactivation problem caused by high concentrations of chloride ions, and has excellent mass transfer performance and free radical generation capacity, thereby effectively degrading the high concentration of organic matter in the high-chlorine and high-organic-content wastewater. Then, the first effluent is transported to a buffer tank 22 and held for a preset residence time to obtain a second effluent. The buffer tank 22 accommodates the first effluent obtained after ozone micro-nano bubble oxidation treatment and holds it for a preset residence time, which allows the residual ozone in the wastewater to decay. Next, the second effluent is heated to a preset temperature range to obtain a third effluent. Through heating treatment, the decay of residual ozone can be accelerated, and the catalytic decomposition effect of the subsequent filter tower 42 on the residual ozone in the wastewater can be improved. Finally, the third effluent is sent to a filter tower 42 filled with modified steel slag filter media for filtration to obtain the fourth effluent. The modified steel slag filter media catalytically decomposes residual ozone in the wastewater, thereby reducing the residual ozone concentration. The treatment method for high-chlorine, high-organic-content wastewater provided in this embodiment not only solves the problem of excessively high residual ozone concentration caused by high-concentration ozone addition, but also ensures that the ORP value of the final effluent meets the feed water requirements of subsequent reverse osmosis and nanofiltration membrane processes, thus guaranteeing the normal operation of the multi-stage membrane concentration and desalination system.

[0023] For example, please continue to see Figure 2 ,like Figure 2 As shown, in some exemplary embodiments, step S100, which involves treating the high-chlorine, high-organic-content wastewater with ozone micro-nano bubble oxidation to obtain a first effluent, includes: S111: The high-chlorine, high-organic-content wastewater is transported to the ozone contact tank 12; S112: Ozone gas is delivered to the ozone contact tank 12 in the form of micro-nano bubbles so that the high-chlorine and high-organic wastewater undergoes an ozone catalytic oxidation reaction with the ozone gas to obtain the first effluent.

[0024] It should be noted that in step S111, the high-chlorine, high-organic-content wastewater can be transported to the ozone contact tank 12 by connecting the first inlet pump 11 to the inlet end of the ozone contact tank 12; in step S112, an ozone generator 14 and a micro-nano bubble generator 13 can be set up, the ozone generator 14 and the micro-nano bubble generator 13 can be connected, and the micro-nano bubble generator 13 can be connected to the ozone contact tank 12, so that the ozone generator 14 can provide ozone gas to the micro-nano bubble generator 13, and the ozone gas can be transported to the ozone contact tank 12 in the form of micro-nano bubbles through the micro-nano bubble generator 13. In order to ensure sufficient ozone dosage, the micro-nano bubble generator 13 and the ozone contact tank 12 are bidirectionally connected so that the high-chlorine, high-organic-content wastewater circulates between the micro-nano bubble generator 13 and the ozone contact tank 12, thereby efficiently degrading the high concentration of organic matter in the wastewater.

[0025] Preferably, in some embodiments, the air source of the ozone generator 14 is pure oxygen, and the conversion efficiency of the oxygen source ozone generator 14 is about 8%wt to 10%wt.

[0026] Furthermore, in some embodiments, the micro / nano bubble generator 13 can employ a shear dispersion method or a dissolved gas release method. The micro / nano bubble generator 13 uses a post-pump air intake configuration, with the air intake providing quantitative adjustment. The gas-liquid ratio is 1:5 to 1:12, the inlet water pressure is 0.2 MPa to 0.45 MPa, and the outlet water pressure is 0.1 MPa to 0.25 MPa. The residence time in the gas-liquid mixing section is ensured to be no less than 2 minutes. The bubble particle size distribution generated by the micro / nano bubble generator 13 is 80 nm to 450 nm, with a median particle size of 100 nm to 450 nm, and the bubble concentration index is no less than 2 × 10⁻⁶. 7 per ml.

[0027] Preferably, in some embodiments, the ozone concentration in the high-chlorine, high-organic-content wastewater per unit time is the ratio of the mass of ozone generated by the ozone generator 14 per unit time to the circulating water flow rate through the micro-nano bubble generator 13 per unit time.

[0028] For example, in step S200, a second inlet pump 21 can be connected between the outlet end of the ozone contact tank 12 and the inlet end of the buffer tank 22 to deliver the first effluent to the buffer tank 22. The preset residence time of the buffer tank 22 can be in the range of 1.5 hours to 4 hours.

[0029] For example, please continue to see Figure 2 ,like Figure 2As shown, in some exemplary embodiments, step S300, heating the second effluent to a preset temperature range to obtain the third effluent, includes: S311: The second outlet water is transported to the heat exchanger 32, and a heat source is supplied to the heat exchanger 32 so that the second outlet water is heated to a preset temperature range of 30 degrees Celsius to 65 degrees Celsius to obtain the third outlet water.

[0030] It should be noted that in step S311, a third inlet pump 31 can be connected between the outlet end of the buffer tank 22 and the wastewater inlet end of the heat exchanger 32 to deliver the second effluent to the heat exchanger 32. Simultaneously, a heat source is supplied to the heat source inlet end of the heat exchanger 32, allowing the second effluent to exchange heat with the heat source in the heat exchanger 32, thereby heating the second effluent. Furthermore, it should be noted that the present invention does not impose excessive limitations on the type of heat exchanger 32. Exemplarily, in some embodiments, the heat exchanger 32 can be a plate heat exchanger.

[0031] For example, in some exemplary embodiments, the heat source may be condensate from an MVR evaporator at 70°C to 90°C; in other embodiments, the heat source may be steam at 0.3 MPa to 0.5 MPa or high-temperature circulating water at 60°C to 80°C.

[0032] For example, please continue to see Figure 2 ,like Figure 2 As shown, in some embodiments, a third effluent can be delivered to the filter tower 42 filled with modified steel slag filter media by connecting a fourth inlet pump 41 between the wastewater outlet of the heat exchanger 32 and the inlet of the filter tower 42.

[0033] Preferably, in some exemplary embodiments, the modified steel slag filter medium is prepared from steel slag raw material, dilute sulfuric acid solution, dilute manganese sulfate solution, and sodium carbonate powder. The steel slag raw material, by mass percentage, has a total FeO and Fe2O3 content of 5%–20% and a SiO2 content of 7%–12%. The modified steel slag filter medium is prepared through the following steps: SA1: The steel slag raw material is ball-milled and screened using a multi-stage standard sieve between 5 mesh and 40 mesh. The slag particles are then graded according to the mesh size of the standard sieve used, and the steel slag particles of each mesh size range are collected separately. SA2: Soak the steel slag particles of each grade in a dilute manganese sulfate solution with a concentration of 0.2 mg / L to 3.5 mg / L, and let them stand for 4 to 8 hours. SA3: All grades of steel slag particles are mixed with sodium carbonate powder at a mass ratio of 93%:7% to 99%:1% and then fed into a heating device. The temperature is increased to 850°C to 950°C at a rate of 1°C / min to 10°C / min and then maintained for 20 minutes to 85 minutes to obtain calcined steel slag. SA4: After cooling the slag to room temperature, remove it and soak it in a dilute sulfuric acid solution with a pH of 4 to 6. Then heat the dilute sulfuric acid solution to 40 to 70 degrees Celsius and keep it for 1 to 4 hours. SA5: The slag is removed and rinsed with water 3 to 5 times, and then dried to obtain the modified slag filter medium.

[0034] It should be noted that during the heating process in step SA3, carbonaceous substances are burned and sulfur-containing substances are converted. Sodium carbonate powder can promote the foaming and maturation of steel slag particles, causing the iron oxides and silicon oxides in the steel slag particles to foam into a more porous structure, increasing the specific surface area of ​​the steel slag particles. This can improve the ozone catalytic decomposition performance of the modified steel slag filter media, laying a good foundation for the catalytic decomposition of residual ozone in high-chlorine and high-organic wastewater.

[0035] Additionally, it should be noted that the present invention does not impose excessive limitations on the type of heating device in step SA3. For example, in some embodiments, the heating device may be a muffle furnace.

[0036] For example, in some exemplary embodiments, the modified steel slag filter media accounts for 60% to 80% of the volume of the filter tower 42.

[0037] Exemplary examples, in some of these exemplary embodiments, the bottom of the filter tower 42 is filled with a modified steel slag filter medium consisting of steel slag particles ranging from 5 to 10 mesh (i.e., steel slag particles that can pass through a 5-mesh standard sieve but not a 10-mesh standard sieve) separated by a 5-mesh and a 10-mesh standard sieve, the volume of which accounts for 40% to 50% of the volume of the filter tower 42; the top of the filter tower 42 is filled with a modified steel slag filter medium consisting of steel slag particles ranging from 20 to 40 mesh (i.e., steel slag particles that can pass through a 20-mesh standard sieve but not a 40-mesh standard sieve) separated by a 20-mesh and a 40-mesh standard sieve, the volume of which accounts for 5% to 30% of the volume of the filter tower 42; efficient mass transfer and coarse filtration are achieved through the large particle bottom layer, while the small particle top layer provides high catalytic activity, thereby forming a "coarse filtration-fine catalysis" gradient reaction structure.

[0038] For example, in some embodiments, the bottom of the filter tower 42 is provided with an air aeration disc, the pore size of which is 5 micrometers to 50 micrometers, the bubble particle size is not higher than 500 micrometers, and the air flow rate is 0.5 Nm. 3 / h~5Nm 3 / h.

[0039] For example, in some embodiments, after the filter tower 42 has been running continuously for 24 to 72 hours, it is backwashed with compressed air at a pressure of 0.3 MPa for 30 minutes to remove deposited impurities attached to the surface of the steel slag particles and restore the filtration performance.

[0040] For example, in some embodiments, the hydraulic residence time of the filter tower 42 is 0.5 hours to 3 hours.

[0041] Preferably, in some embodiments, the processing method further includes: conveying the fourth effluent to the feed tank of a reverse osmosis system or a nanofiltration system.

[0042] To facilitate a further understanding of the present invention, the following will illustrate the invention with two specific examples of treating high-chlorine, high-organic wastewater using the treatment method provided by the present invention.

[0043] Example 1: The water quality characteristics of the high-chloride, high-organic-content wastewater are as follows: chloride ion concentration of 10695 mg / L, pH value of 7.24, conductivity of 43100 μS / cm, COD concentration of 307 mg / L, and TOC concentration of 56.3 mg / L. The treatment steps for this high-chloride, high-organic-content wastewater are as follows: First, the high-chlorine, high-organic-content wastewater is pumped to the ozone contact tank 12 via the first inlet pump 11. Simultaneously, ozone gas is supplied to the micro-nano bubble generator 13 via the ozone generator 14, and the received ozone gas is then transported to the ozone contact tank 12 in the form of micro-nano bubbles via the micro-nano bubble generator 13. The conversion efficiency of the ozone generator 14 (oxygen source) is approximately 8%wt. The micro-nano bubble generator 13 employs a dissolved gas release method and a post-pump air intake, with adjustable air intake, a gas-liquid ratio of 1:8, an inlet pressure of 0.4 MPa, an outlet pressure of 0.15 MPa, and a residence time of 4 minutes in the gas-liquid mixing section. The bubble particle size distribution of the micro-nano bubble generator 13 ranges from 95 nm to 442 nm, with a median particle size of 260 nm, and a bubble concentration index of 5 × 10⁻⁶. 7The ozone concentration is measured in milliliters. Furthermore, to ensure sufficient ozone dosage, the high-chlorine, high-organic-content wastewater circulates between the micro-nano bubble generator 13 and the ozone contact tank 12, ultimately achieving an ozone concentration of 400 mg / L in the wastewater. After ozone micro-nano bubble oxidation treatment, the high-chlorine, high-organic-content wastewater yields the first effluent. This first effluent has a COD concentration of 153 mg / L, an O / C ratio (i.e., the ratio of ozone dosage to the mass of COD removed from the wastewater) of 2.6:1, and an ORP value greater than 1000 mV.

[0044] Then, the first effluent is transported to the buffer tank 22 by the second inlet pump 21 and left for 3 hours to obtain the second effluent, in which the ORP value is reduced to 853 millivolts.

[0045] Next, the second outlet water is transported to a plate heat exchanger via a third inlet pump 31. The plate heat exchanger uses high-temperature circulating water at 65 degrees Celsius as a heat source, which heats the second outlet water, which has an inlet temperature of 28.6 degrees Celsius, to 47.9 degrees Celsius, resulting in the third outlet water. In the third outlet water, the ORP value is reduced to 408 millivolts.

[0046] The third effluent is then pumped by the fourth inlet pump 41 to a filter tower 42 filled with modified steel slag filter media for filtration. The modified steel slag filter media occupies 60% of the volume of the filter tower 42. The modified steel slag filter media is prepared from steel slag raw materials, dilute sulfuric acid solution, dilute manganese sulfate solution, and sodium carbonate powder. The steel slag raw materials, by mass percentage, have a total FeO and Fe2O3 content of 14.5% and a SiO2 content of 10.3%. The modified steel slag filter media is prepared through the following steps: first, the steel slag raw materials are ball-milled and graded using 5-mesh, 10-mesh, 20-mesh, and 40-mesh standard sieves. Steel slag particles between 5 and 10 mesh (i.e., those that pass through the 5-mesh sieve but not the 10-mesh sieve) and steel slag particles between 20 and 40 mesh (i.e., those that pass through the 20-mesh sieve but not the 40-mesh sieve) are collected as two sets of samples for later use. The two groups of steel slag particles were then immersed in a dilute manganese sulfate solution with a concentration of 0.2 mg / L and allowed to stand for 6 hours. Next, the two groups of steel slag particles after standing were mixed with sodium carbonate powder at a mass ratio of 94%:6% and fed into a muffle furnace. The temperature was increased to 900 degrees Celsius at a rate of 10 degrees Celsius / minute and held for 60 minutes to obtain two groups of calcined steel slag. The two groups of calcined steel slag were then cooled to room temperature and immersed in a dilute sulfuric acid solution with a pH of 4.5. The dilute sulfuric acid solution was heated to 50 degrees Celsius and held for 1 to 4 hours to remove dissolved free iron ions. Finally, the two groups of calcined steel slag were removed, rinsed with water 5 times, and then dried to obtain two groups of modified steel slag filter media with different mesh sizes. In addition, the bottom of the filter tower 42 is filled with a modified steel slag filter medium consisting of steel slag particles ranging from 5 to 10 mesh (i.e., steel slag particles that can pass through a 5-mesh standard sieve but not a 10-mesh standard sieve) separated by a 5-mesh and a 10-mesh standard sieve, and the volume of this modified steel slag filter medium accounts for 40% of the volume of the filter tower 42; the top of the filter tower 42 is filled with a modified steel slag filter medium consisting of steel slag particles ranging from 20 to 40 mesh (i.e., steel slag particles that can pass through a 20-mesh standard sieve but not a 40-mesh standard sieve) separated by a 20-mesh and a 40-mesh standard sieve, and the volume of this modified steel slag filter medium accounts for 20% of the volume of the filter tower 42. The bottom of the filter tower 42 is also equipped with an air aeration disc with a pore size of 50 micrometers, a bubble particle size not exceeding 500 micrometers, and an air flow rate of 4 Nm³. 3 Furthermore, every 24 hours of continuous operation, the filter tower 42 is backwashed for 30 minutes with compressed air at a pressure of 0.3 MPa to remove deposited impurities adhering to the surface of the steel slag particles and restore its filtration performance.

[0047] Finally, the third effluent is retained in the filter tower 42 for 1 hour to obtain the fourth effluent. In the fourth effluent, the ORP value is reduced to 163 millivolts, and it can enter the feed tank of the reverse osmosis system or nanofiltration system.

[0048] Example 2: The water quality characteristics of the high-chloride, high-organic-content wastewater are as follows: chloride ion concentration of 3562 mg / L, pH value of 6.78, conductivity of 18970 μS / cm, COD concentration of 167 mg / L, and TOC concentration of 35.2 mg / L. The treatment steps for this high-chloride, high-organic-content wastewater are as follows: First, the high-chlorine, high-organic-content wastewater is pumped to the ozone contact tank 12 via the first inlet pump 11. Simultaneously, ozone gas is supplied to the micro-nano bubble generator 13 via the ozone generator 14, and the received ozone gas is then transported to the ozone contact tank 12 in the form of micro-nano bubbles via the micro-nano bubble generator 13. The conversion efficiency of the ozone generator 14 (oxygen source) is approximately 8.5%wt. The micro-nano bubble generator 13 employs a hydraulic shear method and a post-pump air intake, with adjustable air intake, a gas-liquid ratio of 1:6.5, an inlet pressure of 0.32 MPa, an outlet pressure of 0.13 MPa, and a residence time of 3.8 minutes in the gas-liquid mixing section. The bubble particle size distribution of the micro-nano bubble generator 13 ranges from 88 nm to 407 nm, with a median particle size of 346 nm, and a bubble concentration of 4.3 × 10⁻⁶. 7 The ozone concentration is measured in milliliters. Additionally, to ensure sufficient ozone dosage, the high-chlorine, high-organic-content wastewater circulates between the micro-nano bubble generator 13 and the ozone contact tank 12, ultimately achieving an ozone concentration of 285 mg / L in the wastewater. After ozone micro-nano bubble oxidation treatment, the high-chlorine, high-organic-content wastewater yields the first effluent. This first effluent has a COD concentration of 87 mg / L, an O / C ratio (i.e., the ratio of ozone dosage to the mass of COD removed from the wastewater) of 3.6:1, and an ORP value greater than 1000 mV.

[0049] Then, the first effluent is pumped to the buffer tank 22 by the second inlet pump 21 and left to stand for 2 hours to obtain the second effluent, in which the ORP value is reduced to 962 millivolts.

[0050] Next, the second outlet water is transported to a plate heat exchanger via a third inlet pump 31. The plate heat exchanger uses the condensate from the MVR evaporator at 73 degrees Celsius as a heat source, so that the second outlet water with an inlet temperature of 23.9 degrees Celsius is heated to 41.4 degrees Celsius to obtain the third outlet water, in which the ORP value is reduced to 352 millivolts.

[0051] The third effluent is then pumped by the fourth inlet pump 41 to a filter tower 42 filled with modified steel slag filter media for filtration. The modified steel slag filter media occupies 70% of the volume of the filter tower 42. The modified steel slag filter media is prepared from steel slag raw materials, dilute sulfuric acid solution, dilute manganese sulfate solution, and sodium carbonate powder. The steel slag raw materials, by mass percentage, have a total FeO and Fe2O3 content of 12.9% and a SiO2 content of 8.4%. The modified steel slag filter media is prepared through the following steps: first, the steel slag raw materials are ball-milled and graded using 5-mesh, 10-mesh, 30-mesh, and 40-mesh standard sieves. Steel slag particles between 5 and 10 mesh (i.e., those that pass through the 5-mesh sieve but not the 10-mesh sieve) and steel slag particles between 30 and 40 mesh (i.e., those that pass through the 30-mesh sieve but not the 40-mesh sieve) are collected as two sets of samples for later use. Then… Two groups of steel slag particles were soaked in a dilute manganese sulfate solution with a concentration of 1.8 mg / L and allowed to stand for 4.5 hours. Then, the two groups of steel slag particles were mixed with sodium carbonate powder at a mass ratio of 95%:5% and fed into a muffle furnace. The temperature was increased to 950°C at a rate of 10°C / min and held for 60 minutes to obtain two groups of calcined steel slag. The calcined steel slag was then cooled to room temperature and soaked in a dilute sulfuric acid solution with a pH of 5.0. The sulfuric acid solution was heated to 50°C and held for 1 to 4 hours to remove dissolved free iron ions. Finally, the two groups of calcined steel slag were removed, rinsed five times with water, and then dried to obtain two groups of modified steel slag filter media with different mesh sizes. In addition, the bottom of the filter tower 42 is filled with a modified steel slag filter medium consisting of steel slag particles ranging from 5 to 10 mesh (i.e., steel slag particles that can pass through a 5-mesh standard sieve but not a 10-mesh standard sieve) separated by a 5-mesh and a 10-mesh standard sieve, and the volume of this modified steel slag filter medium accounts for 45% of the volume of the filter tower 42; the top of the filter tower 42 is filled with a modified steel slag filter medium consisting of steel slag particles ranging from 30 to 40 mesh (i.e., steel slag particles that can pass through a 30-mesh standard sieve but not a 40-mesh standard sieve) separated by a 30-mesh and a 40-mesh standard sieve, and the volume of this modified steel slag filter medium accounts for 25% of the volume of the filter tower 42. The bottom of the filter tower 42 is also equipped with an air aeration disc with an aperture of 35 micrometers, a bubble particle size not exceeding 500 micrometers, and an air flow rate of 2.6 Nm³. 3 Furthermore, every 24 hours of continuous operation, the filter tower 42 is backwashed for 30 minutes with compressed air at a pressure of 0.3 MPa to remove deposited impurities adhering to the surface of the steel slag particles and restore its filtration performance.

[0052] Finally, the third effluent is retained in the filter tower 42 for 0.8 hours to obtain the fourth effluent, in which the ORP value is reduced to 175 millivolts, and can enter the feed tank of the reverse osmosis system or nanofiltration system.

[0053] Example 2 This embodiment provides a treatment system for high-chlorine, high-organic-content wastewater. For details, please refer to... Figure 3 and Figure 4 , Figure 3 This is a structural block diagram of the high-chlorine, high-organic-content wastewater treatment system provided in this embodiment; Figure 4 This is a process flow diagram of the high-chlorine, high-organic-content wastewater treatment system provided in this embodiment. From... Figure 3 and Figure 4 As can be seen, the treatment system includes an ozone oxidation unit 1, a buffer treatment unit 2, a heating treatment unit 3, and a filtration unit 4 arranged sequentially. The ozone oxidation unit 1 is configured to perform ozone micro-nano bubble oxidation treatment on the high-chlorine and high-organic wastewater to obtain a first effluent. The buffer treatment unit 2 is configured to transport the first effluent to a buffer tank 22 and retain it for a preset residence time to obtain a second effluent. The heating treatment unit 3 is configured to heat the second effluent to a preset temperature range to obtain a third effluent. The filtration unit 4 is configured to transport the third effluent to a filter tower 42 filled with modified steel slag filter media for filtration treatment to obtain a fourth effluent.

[0054] For example, please continue to see Figure 4 ,like Figure 4 As shown, in some embodiments, the ozone oxidation unit 1 includes a first inlet pump 11 and an ozone contact tank 12 arranged sequentially. A micro / nano bubble generator 13 is connected to the ozone contact tank 12, and an ozone generator 14 is connected to the micro / nano bubble generator 13. The first inlet pump 11 is configured to transport the high-chlorine, high-organic-content wastewater to the ozone contact tank 12. The ozone generator 14 is configured to provide ozone gas to the micro / nano bubble generator 13. The micro / nano bubble generator 13 is configured to transport the received ozone gas to the ozone contact tank 12 in the form of micro / nano bubbles. The ozone contact tank 12 is configured to cause the high-chlorine, high-organic-content wastewater to undergo an ozone catalytic oxidation reaction with the ozone gas to obtain the first effluent.

[0055] For example, in some embodiments, the buffer processing unit 2 includes a second inlet pump 21 and a buffer tank 22 arranged in sequence; the second inlet pump 21 is configured to: deliver the first effluent to the buffer tank 22; the buffer tank 22 is configured to: receive the first effluent and keep it there for a preset time to obtain the second effluent.

[0056] For example, in some embodiments, the heating treatment unit 3 includes a third water inlet pump 31 and a heat exchanger 32 arranged in sequence; the third water inlet pump 31 is configured to deliver the second effluent to the heat exchanger 32; the heat exchanger 32 is configured to heat the second effluent to a preset temperature range to obtain the third effluent.

[0057] For example, in some embodiments, the filtration unit 4 includes a fourth inlet pump 41 and the filter tower 42 arranged in sequence; the fourth inlet pump 41 is configured to deliver the third effluent to the filter tower 42; the filter tower 42 is configured to filter the third effluent using the modified steel slag filter medium to obtain the fourth effluent.

[0058] Since the high-chlorine, high-organic-content wastewater treatment system provided in this embodiment belongs to the same inventive concept as the high-chlorine, high-organic-content wastewater treatment method provided in any of the above embodiments, the high-chlorine, high-organic-content wastewater treatment system provided in this embodiment possesses at least all the advantages of the high-chlorine, high-organic-content wastewater treatment methods provided in the above embodiments. For details regarding the advantages of the high-chlorine, high-organic-content wastewater treatment system provided in this embodiment, please refer to the relevant descriptions of the beneficial effects of the high-chlorine, high-organic-content wastewater treatment methods provided in the above embodiments; these will not be repeated here. Furthermore, the high-chlorine, high-organic-content wastewater treatment system provided in this embodiment is easy to operate, possesses strong practicality and reliability, and by combining an ozone generator, a micro-nano bubble generator, a buffer tank, a heat exchanger, and a filter tower filled with modified steel slag filter media, it can effectively treat high-chlorine, high-organic-content wastewater, providing a new technical approach for advanced wastewater treatment and zero-discharge treatment, and has broad application prospects.

[0059] In summary, the treatment method and system for high-chlorine, high-organic-content wastewater provided by this invention have the following advantages: The method first treats the wastewater with ozone micro-nano bubble oxidation to obtain a first effluent. By employing ozone micro-nano bubble technology, the concentration and mass transfer efficiency of ozone in the wastewater can be significantly improved. Compared with traditional ozone catalytic oxidation processes, ozone micro-nano bubble technology requires no catalyst, avoiding catalytic deactivation caused by high concentrations of chloride ions, and possesses excellent mass transfer performance and free radical generation capacity, thus effectively degrading high concentrations of organic matter in the high-chlorine, high-organic-content wastewater. Then, the first effluent is transported to a buffer tank and held for a preset residence time to obtain a second effluent. The buffer tank accommodates the first effluent obtained after ozone micro-nano bubble oxidation treatment and holds it for the preset residence time, allowing residual ozone in the wastewater to decay. Next, the second effluent is heated to a preset temperature range to obtain the third effluent. This heating treatment accelerates the decay of residual ozone and enhances the catalytic decomposition effect of the subsequent filtration tower on residual ozone in the wastewater. Finally, the third effluent is sent to a filtration tower filled with modified steel slag filter media for filtration treatment to obtain the fourth effluent. The modified steel slag filter media catalytically decomposes residual ozone in the wastewater, thereby reducing its concentration. The treatment method for high-chlorine, high-organic-content wastewater provided by this invention not only solves the problem of excessively high residual ozone concentration caused by high-concentration ozone addition but also ensures that the ORP value of the final effluent meets the feed water requirements of subsequent reverse osmosis and nanofiltration membrane processes, thus guaranteeing the normal operation of the multi-stage membrane concentration and desalination system.

[0060] Since the high-chlorine, high-organic-content wastewater treatment system provided by this invention and the high-chlorine, high-organic-content wastewater treatment method provided by this invention belong to the same inventive concept, the high-chlorine, high-organic-content wastewater treatment system provided by this invention has at least all the advantages of the high-chlorine, high-organic-content wastewater treatment method provided by this invention. For the advantages of the high-chlorine, high-organic-content wastewater treatment system provided by this invention, please refer to the relevant description of the beneficial effects of the high-chlorine, high-organic-content wastewater treatment method provided by this invention, which will not be repeated here.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for treating high-chlorine, high-organic-content wastewater, characterized in that, The processing method includes: The high-chlorine, high-organic-content wastewater was subjected to ozone micro-nano bubble oxidation treatment to obtain the first effluent. The first effluent is transported to a buffer tank and left to stand for a preset duration to obtain the second effluent; The second outlet water is heated to a preset temperature range to obtain the third outlet water; The third effluent is transported to a filter tower filled with modified steel slag filter media for filtration treatment to obtain the fourth effluent.

2. The method for treating high-chlorine, high-organic-content wastewater as described in claim 1, characterized in that, The ozone micro-nano bubble oxidation treatment of the high-chlorine, high-organic-content wastewater to obtain the first effluent includes: The high-chlorine, high-organic-content wastewater is transported to an ozone contact tank. Ozone gas is delivered to the ozone contact tank in the form of micro-nano bubbles, so that the high-chlorine and high-organic wastewater undergoes an ozone catalytic oxidation reaction with the ozone gas to obtain the first effluent.

3. The method for treating high-chlorine, high-organic-content wastewater as described in claim 1, characterized in that, The preset stay duration ranges from 1.5 hours to 4 hours.

4. The method for treating high-chlorine, high-organic-content wastewater as described in claim 1, characterized in that, The step of heating the second effluent to a preset temperature range to obtain the third effluent includes: The second effluent is delivered to a heat exchanger, and a heat source is supplied to the heat exchanger to heat the second effluent to a preset temperature range of 30 degrees Celsius to 65 degrees Celsius, thereby obtaining the third effluent.

5. The method for treating high-chlorine, high-organic-content wastewater as described in claim 1, characterized in that, The modified steel slag filter medium is prepared from steel slag raw materials, dilute sulfuric acid solution, dilute manganese sulfate solution, and sodium carbonate powder. The steel slag raw materials, by mass percentage, have a total FeO and Fe2O3 content of 5%–20% and a SiO2 content of 7%–12%. The modified steel slag filter medium is prepared through the following steps: The steel slag raw material is ball-milled and sieved using a multi-stage standard sieve between 5 and 40 mesh. The slag particles are then graded according to the mesh size of the standard sieve used, and steel slag particles of each mesh size range are collected separately. Each grade of steel slag particles was soaked in a dilute manganese sulfate solution with a concentration of 0.2 mg / L to 3.5 mg / L and left to stand for 4 to 8 hours. All grades of steel slag particles are mixed with sodium carbonate powder at a mass ratio of 93%:7% to 99%:1% and then fed into a heating device. The temperature is increased to 850°C to 950°C at a rate of 1°C to 10°C per minute and then maintained for 20 minutes to 85 minutes to obtain calcined steel slag. After the slag is cooled to room temperature, it is taken out and soaked in a dilute sulfuric acid solution with a pH of 4 to 6. The dilute sulfuric acid solution is then heated to 40 to 70 degrees Celsius and kept at that temperature for 1 to 4 hours. The aging steel slag is removed and rinsed with water 3 to 5 times, and then dried to obtain the modified steel slag filter medium.

6. A treatment system for high-chlorine, high-organic-content wastewater, characterized in that, The processing system includes an ozone oxidation unit, a buffer treatment unit, a heating treatment unit, and a filtration unit arranged in sequence. The ozone oxidation unit is configured to perform ozone micro-nano bubble oxidation treatment on the high-chlorine and high-organic wastewater to obtain the first effluent. The buffer processing unit is configured to: deliver the first effluent to the buffer tank and let it stay for a preset duration to obtain the second effluent; The heating unit is configured to heat the second effluent to a preset temperature range to obtain the third effluent; The filtration unit is configured to: transport the third effluent to a filtration tower filled with modified steel slag filter media for filtration treatment to obtain the fourth effluent.

7. The treatment system for high-chlorine, high-organic-content wastewater as described in claim 6, characterized in that, The ozone oxidation unit includes a first water inlet pump and an ozone contact tank arranged in sequence. A micro-nano bubble generator is connected to the ozone contact tank, and an ozone generator is connected to the micro-nano bubble generator. The first inlet pump is configured to: transport the high-chlorine, high-organic-content wastewater to the ozone contact tank; The ozone generator is configured to provide ozone gas to the micro / nano bubble generator; The micro-nano bubble generator is configured to deliver the received ozone gas to the ozone contact pool in the form of micro-nano bubbles. The ozone contact tank is configured to cause the high-chlorine, high-organic-content wastewater to undergo an ozone catalytic oxidation reaction with the ozone gas to obtain the first effluent.

8. The treatment system for high-chlorine, high-organic-content wastewater as described in claim 6, characterized in that, The buffer processing unit includes a second inlet pump and a buffer tank arranged in sequence. The second inlet pump is configured to deliver the first outlet water to the buffer tank; The buffer pool is configured to receive the first effluent and allow it to remain for a preset duration to obtain the second effluent.

9. The treatment system for high-chlorine, high-organic-content wastewater as described in claim 6, characterized in that, The heating treatment unit includes a third inlet water pump and a heat exchanger arranged in sequence. The third inlet pump is configured to deliver the second outlet water to the heat exchanger; The heat exchanger is configured to heat the second outlet water to a preset temperature range to obtain the third outlet water.

10. The treatment system for high-chlorine, high-organic-content wastewater as described in claim 6, characterized in that, The filtration unit includes a fourth inlet pump and the filtration tower arranged in sequence. The fourth inlet pump is configured to deliver the third outlet water to the filter tower; The filter tower is configured to filter the third effluent using the modified steel slag filter medium to obtain the fourth effluent.

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