Method and device for removing organic pollutants from wastewater

Abstract

This invention provides a method and apparatus for removing organic pollutants from wastewater. The method includes the following steps: S1, separating the wastewater to be treated into neutral water, acidic water, and alkaline water via electrodialysis; S2, performing any one of the following steps a, b, or c: Step a: when organic pollutants are only present in the neutral water, mixing and stirring the neutral water and an oxidant to obtain purified water; Step b: when organic pollutants are present simultaneously in neutral water, acidic water, and alkaline water, adding calcium salt to the alkaline water, and then mixing and stirring it with the acidic water, neutral water, and oxidant to obtain purified water; Step c: when organic pollutants are present in both acidic and alkaline water, adding calcium salt to the alkaline water, and then mixing and stirring it with the acidic water and oxidant to obtain purified water. Compared with traditional advanced oxidation water purification technologies, this method improves the oxidation and decomposition efficiency of organic pollutants and helps reduce the amount of oxidant required.

Description

Technical Field

[0001] This invention relates to the field of water treatment, and more particularly to a method and apparatus for removing organic pollutants from wastewater. Background Technology

[0002] The production and use of chemical substances inevitably generate wastewater. Traditional "physical-chemical + biological" treatment technologies cannot completely remove all organic pollutants from the water. Therefore, industrial wastewater usually requires further advanced treatment. Currently, commonly used advanced wastewater treatment technologies include adsorption, advanced oxidation, and membrane separation. Among them, advanced oxidation technology can generate highly oxidizing active substances, such as hydroxyl radicals and superoxide radicals, to oxidize and decompose organic pollutants in the water. It is currently the most widely used advanced industrial wastewater treatment technology.

[0003] Although highly reactive oxidizing agents produced during advanced oxidation processes can oxidize and decompose organic pollutants in water, actual water bodies, especially industrial wastewater, contain a large amount of background substances such as inorganic anions and natural organic matter. Highly reactive oxidizing agents are not selective and can also react with background substances in the water. In particular, bicarbonates and phosphates in the water have the most significant interference effect on pollutant removal. Therefore, when treating organic pollutants in actual industrial wastewater, it is usually necessary to increase the input of oxidants or energy, which will not only increase operating costs but may also bring the risk of generating byproducts. Summary of the Invention

[0004] This invention provides a method for removing organic pollutants from wastewater. Compared with traditional advanced oxidation water purification technology, this method improves the oxidation and decomposition efficiency of organic pollutants, helps reduce the amount of oxidant added and energy consumption, and thus helps to reduce operating costs.

[0005] The present invention also provides an apparatus for removing organic pollutants from wastewater, which can be used in the above-described method.

[0006] On one hand, the present invention provides a method for removing organic pollutants from wastewater, comprising the following steps:

[0007] S1. The wastewater to be treated is divided into three parts by electrodialysis: one part is neutral water, one part is acidic water containing cations, and the other part is alkaline water containing anions.

[0008] S2. Perform any one of the following steps: a, b, or c

[0009] Step a: When organic pollutants are only present in the neutral water, the neutral water and oxidant are directly mixed and stirred to remove the organic pollutants and obtain purified water;

[0010] Step b: When organic pollutants are present simultaneously in neutral water, acidic water, and alkaline water, calcium salt is added to the alkaline water. 2+ The organic pollutants react with phosphate and carbonate to form precipitates, and the solid and liquid are separated to obtain pre-purified alkaline water. Acidic water, neutral water, pre-purified alkaline water and oxidant are mixed and stirred to remove the organic pollutants and obtain purified water.

[0011] Step c: When organic pollutants are present in both acidic and alkaline water, calcium salt is added to the alkaline water. 2+ The solution reacts with phosphate and carbonate ions to form precipitates, and the solid and liquid are separated to obtain pre-purified alkaline water. The acidic water, the pre-purified alkaline water, and the oxidant are mixed and stirred to remove the organic pollutants and obtain purified water.

[0012] Furthermore, the oxidant includes hydrogen peroxide and Fe. 2+ .

[0013] Furthermore, the hydrogen peroxide and Fe 2+ The molar ratio is 2:1.

[0014] Furthermore, the wastewater to be treated undergoes coagulation and sedimentation treatment before step S1.

[0015] Furthermore, after obtaining purified water in step a, the process further includes the following steps: mixing the purified water and alkaline water, adding calcium salts, Ca... 2+ After reacting with phosphate and carbonate ions to form precipitates, solid-liquid separation occurs.

[0016] After obtaining purified water in step b, the process further includes the following steps: The purified water is further treated by electrodialysis to divide it into three parts: neutral water, acidic water containing cations, and alkaline water containing anions. Calcium salts, Ca... 2+ It reacts with phosphate and carbonate ions to form precipitates, resulting in solid-liquid separation;

[0017] After obtaining purified water in step c, the process further includes the following steps: the purified water and neutral water are mixed, and the mixture is then treated by electrodialysis to divide it into three parts: one part is neutral water, one part is acidic water containing cations, and the other part is alkaline water containing anions. Calcium salts, Ca... 2+ It reacts with phosphate and carbonate ions to form precipitates, thus separating the solid and liquid phases.

[0018] In another aspect, the present invention provides an apparatus for removing organic pollutants from wastewater, the apparatus comprising: an electrodialysis unit, a phosphate and bicarbonate removal unit, and an advanced oxidation unit; the electrodialysis unit comprising a wastewater inlet, a neutral water outlet, an acidic water outlet, and a first alkaline water outlet; the phosphate and bicarbonate removal unit comprising a first alkaline water inlet, a calcium salt inlet, and a second alkaline water outlet; the advanced oxidation unit comprising a neutral water inlet, an acidic water inlet, a second alkaline water inlet, an oxidant inlet, and a purified water outlet;

[0019] The first alkaline water outlet is connected to the first alkaline water inlet via a first pipe, the second alkaline water outlet is connected to the second alkaline water inlet via a second pipe, the neutral water outlet is connected to the neutral water inlet via a third pipe, and the acidic water outlet is connected to the acidic water inlet via a fourth pipe; each of the first, second, third, and fourth pipes is equipped with a check valve and a flow control valve.

[0020] Furthermore, it also includes a filtration unit, which is disposed inside the phosphate and bicarbonate removal unit, and alkaline water flows out from the second alkaline water outlet after passing through the filtration unit.

[0021] Furthermore, it also includes a coagulation sedimentation unit, located before the electrodialysis unit. The coagulation sedimentation unit includes a first wastewater inlet and a first wastewater outlet, and the first wastewater outlet is connected to the wastewater inlet of the electrodialysis unit.

[0022] Furthermore, the phosphate and bicarbonate removal unit also includes a solids outlet.

[0023] Furthermore, it also includes a phosphate removal unit, which includes a first purified water inlet, a calcium salt inlet, and a first purified water outlet, wherein the first purified water inlet is connected to the purified water outlet of the advanced oxidation unit.

[0024] The method for removing organic pollutants from wastewater provided by this invention reduces the competitive reaction between phosphates and bicarbonates and highly reactive oxidizing substances by preferentially removing them, thereby improving the efficiency of oxidative decomposition of organic pollutants, reducing the amount of oxidant added and energy consumption, and thus lowering operating costs. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0026] Figure 1 This invention provides a specific embodiment of an apparatus for removing organic pollutants from wastewater.

[0027] In the diagram, 001 is the electrodialysis unit, 002 is the phosphate and bicarbonate removal unit, 003 is the advanced oxidation unit, 004 is the first pipeline, 005 is the second pipeline, 006 is the third pipeline, 007 is the fourth pipeline, 008 is the coagulation and sedimentation unit, and 009 is the phosphate removal unit.

[0028] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of the application will be clearly and completely described below in conjunction with the embodiments of the invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, the terms describing positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0032] In this invention, the term "COD" refers to chemical oxygen demand, which is the amount of oxidant consumed when a water sample is treated with a certain strong oxidant under certain conditions. COD is an indicator of the amount of reducing substances (especially organic matter) in water.

[0033] In a first aspect, the present invention provides a method for removing organic pollutants from wastewater, comprising the following steps:

[0034] S1. The wastewater to be treated is divided into three parts by electrodialysis: one part is neutral water, one part is acidic water containing cations, and the other part is alkaline water containing anions.

[0035] S2. Perform any one of the following steps: a, b, or c

[0036] Step a: When organic pollutants are only present in the neutral water, the neutral water and oxidant are directly mixed and stirred to remove the organic pollutants and obtain purified water;

[0037] Step b: When organic pollutants are present simultaneously in neutral water, acidic water, and alkaline water, calcium salt is added to the alkaline water. 2+ The organic pollutants react with phosphate and carbonate to form precipitates, and the solid and liquid are separated to obtain pre-purified alkaline water. Acidic water, neutral water, pre-purified alkaline water and oxidant are mixed and stirred to remove the organic pollutants and obtain purified water.

[0038] Step c: When organic pollutants are present in both acidic and alkaline water, calcium salt is added to the alkaline water. 2+ The solution reacts with phosphate and carbonate ions to form precipitates, and the solid and liquid are separated to obtain pre-purified alkaline water. The acidic water, the pre-purified alkaline water, and the oxidant are mixed and stirred to remove the organic pollutants and obtain purified water.

[0039] It is understandable that wastewater contains a variety of organic pollutants, some of which can be ionized through electrodialysis. Therefore, the removal of organic pollutants in step S2 can be divided into the following three cases:

[0040] If the organic pollutants in the wastewater still exist in molecular form after electrodialysis treatment, that is, the organic pollutants only exist in the neutral water, then step a is performed to directly mix and stir the neutral water and the oxidant to remove the organic pollutants.

[0041] When organic pollutants in wastewater can be partially ionized and partially exist in molecular form after electrodialysis treatment, that is, organic pollutants exist simultaneously in neutral water, acidic water and alkaline water, then step b is performed to mix and stir acidic water, neutral water, pre-purified alkaline water and oxidant to remove the organic pollutants.

[0042] When all organic pollutants in the wastewater are ionized through electrodialysis, i.e., the organic pollutants exist in both acidic and alkaline water, step c is performed where acidic water, pre-purified alkaline water, and oxidant are mixed and stirred to remove the organic pollutants.

[0043] In step a, organic pollutants are separated from phosphate and bicarbonate ions through electrodialysis, thereby avoiding competitive reactions between phosphate and bicarbonate ions and highly reactive oxidizing agents, thus improving the oxidative decomposition efficiency of organic pollutants. Steps b and c involve first dividing the wastewater into three parts through electrodialysis. The phosphate and bicarbonate ions are completely separated into alkaline water containing anions. Under alkaline conditions, bicarbonate ions become carbonate ions. Then, calcium salts (usually calcium chloride) are added to remove phosphate and bicarbonate ions, avoiding competitive reactions between phosphate and bicarbonate ions and highly reactive oxidizing agents, thereby improving the oxidative decomposition efficiency of organic pollutants.

[0044] In step S2, the preferred source of calcium salt is calcium chloride. As for the amount added, the present invention does not impose a specific limitation, and those skilled in the art can adjust it according to the situation. For example, calcium salt can be added slowly and continuously until no more precipitation occurs, at which point the addition of calcium salt can be stopped. Similarly, the present invention does not impose a specific limitation on the amount of oxidant added, and those skilled in the art can adjust it according to the situation. For example, oxidant can be added continuously until the COD value of the wastewater no longer changes, at which point the addition of oxidant can be stopped.

[0045] In an alternative embodiment, the oxidant comprises hydrogen peroxide and Fe. 2+ It can be understood that this implementation method mainly utilizes the Fenton reaction to oxidize and reduce organic pollutants in water. Preferably, Fe... 2+ Source: Ferrous sulfate.

[0046] To reduce waste of Fenton's reagent, preferably, the hydrogen peroxide reacts with Fe... 2+ The molar ratio is 2:1.

[0047] In one alternative embodiment, the wastewater to be treated undergoes coagulation and sedimentation treatment before step S1.

[0048] Although the method of this invention achieves the removal of organic pollutants from water, phosphate and bicarbonate ions still exist in acidic and alkaline water after step a. After steps b and c, the organic pollutants decompose to generate small molecule phosphate ions. Therefore, in an optional embodiment, after obtaining purified water in step a, the following process is further included: mixing the purified water and alkaline water, and adding calcium salt Ca. 2+ After reacting with phosphate and carbonate ions to form precipitates, solid-liquid separation occurs.

[0049] After obtaining purified water in step b, the process further includes the following steps: The purified water is further treated by electrodialysis to divide it into three parts: neutral water, acidic water containing cations, and alkaline water containing anions. Calcium salts, Ca... 2+ It reacts with phosphate and carbonate ions to form precipitates, resulting in solid-liquid separation;

[0050] After obtaining purified water in step c, the following process is also included: the purified water and neutral water are mixed, and the mixture is further treated by electrodialysis to divide it into three parts: one part is neutral water, one part is acidic water containing cations, and the other part is alkaline water containing anions. Ca2+ is added to the alkaline water, and Ca2+ reacts with phosphate and carbonate to form precipitates, thus separating the solid and liquid.

[0051] The above implementation methods not only remove organic pollutants from the water, but also remove phosphate and carbonate ions, further improving the purification level of wastewater.

[0052] Secondly, the present invention provides an apparatus for removing organic pollutants from wastewater, combined with Figure 1 The device includes: an electrodialysis unit 001, a phosphate and bicarbonate removal unit 002, and an advanced oxidation unit 003; the electrodialysis unit includes a wastewater inlet, a neutral water outlet, an acidic water outlet, and a first alkaline water outlet; the phosphate and bicarbonate removal unit includes a first alkaline water inlet, a calcium salt inlet, and a second alkaline water outlet; the advanced oxidation unit includes a neutral water inlet, an acidic water inlet, a second alkaline water inlet, an oxidant inlet, and a purified water outlet;

[0053] The first alkaline water outlet is connected to the first alkaline water inlet via the first pipe 004, the second alkaline water outlet is connected to the second alkaline water inlet via the second pipe 005, the neutral water outlet is connected to the neutral water inlet via the third pipe 006, and the acidic water outlet is connected to the acidic water inlet via the fourth pipe 007; each of the first, second, third, and fourth pipes is equipped with a check valve and a flow control valve.

[0054] It is understood that the above-described apparatus can be used in the method of the first aspect of the present invention, and when used in the above-described method, it includes the following steps:

[0055] S1. The wastewater to be treated enters the electrodialysis unit 001 through the wastewater inlet. After treatment, it is divided into three parts: one part is neutral water, one part is acidic water containing cations, and the other part is alkaline water containing anions. Neutral water flows out from the neutral water outlet, acidic water flows out from the acidic water outlet, and alkaline water flows out from the first alkaline water outlet.

[0056] S2. Perform any one of the following steps: a, b, or c

[0057] Step a: Use a testing device to test the COD value of the above three parts of water. When organic pollutants are only present in the neutral water, adjust the flow control valves of the first pipe 004, the third pipe 006 and the fourth pipe 007 so that the liquid flow of the first pipe 004 and the fourth pipe 007 is 0. The neutral water enters the advanced oxidation unit 003 through the third pipe 006. The oxidant is introduced from the above oxidant inlet. The oxidant and the neutral water come into contact and an oxidation reaction occurs to remove organic pollutants and obtain purified water.

[0058] Step b: Use a testing device to test the COD value of the above three parts of water. When organic pollutants are present in neutral water, acidic water and alkaline water at the same time, adjust the flow control valves of the first pipe 004, the second pipe 005, the third pipe 006 and the fourth pipe 007 to ensure that the liquids pass through normally. Alkaline water flows into the phosphate and bicarbonate removal unit 002 through the first pipe 004. Calcium salt is added from the calcium salt inlet. The bicarbonate in the alkaline water becomes carbonate. The carbonate, phosphate and calcium salt come into contact and react to generate precipitate and pre-purified alkaline water. The pre-purified alkaline water flows into the advanced oxidation unit 003 through the second pipe 005. Neutral water and acidic water flow into the advanced oxidation unit 003 through the third pipe 006 and the fourth pipe 007 respectively. Oxidant is added from the above oxidant inlet. The oxidant comes into contact with the mixed water and undergoes an oxidation reaction to remove organic pollutants and obtain purified water.

[0059] Step c: Use a testing device to test the COD value of the above three parts of water. When organic pollutants are present in acidic and alkaline water, adjust the flow control valves of the first pipe 004, the second pipe 005, and the fourth pipe 007 to ensure that the liquids pass through normally. Alkaline water flows into the phosphate and bicarbonate removal unit 002 through the first pipe 004. Calcium chloride is added from the calcium salt inlet, and the bicarbonate in the alkaline water becomes carbonate. The carbonate, phosphate, and calcium salts come into contact and react to generate precipitate and pre-purified alkaline water. The pre-purified alkaline water flows into the advanced oxidation unit 003 through the second pipe 005. Acidic water flows into the advanced oxidation unit 003 through the fourth pipe 007. Oxidant is added from the above-mentioned oxidant inlet. The oxidant comes into contact with the mixed water and undergoes an oxidation reaction to remove organic pollutants and obtain purified water.

[0060] In one specific embodiment, the electrodialysis unit 001, the phosphate and bicarbonate removal unit 002, and the advanced oxidation unit 003 all include a housing capable of containing liquids. This housing can be configured in any form capable of containing wastewater, such as any housing composed of a cylinder, a cube, a prism, etc., consisting of a top surface, a top surface, and a side surface.

[0061] The present invention does not impose any particular limitation on the electrodialysis unit 001, and pre-assembled devices can be purchased from the market, such as those mainly including a power source, anion and cation exchange membranes, a desalination chamber, and a concentrate chamber.

[0062] The aforementioned phosphate and bicarbonate removal unit 002 and advanced oxidation unit 003 are all equipped with a stirring element to stir the liquid to form a vortex and increase the solid-liquid contact area.

[0063] In one specific embodiment, a filtration unit is further included, disposed inside the phosphate and bicarbonate removal unit 002. Alkaline water passes through the filtration unit and flows out from the second alkaline water outlet. Exemplarily, the filtration unit is a filter membrane, which allows liquid to pass through while retaining solids within the phosphate and bicarbonate removal unit 002; furthermore, the phosphate and bicarbonate removal unit also includes a solids outlet for discharging the solids retained by the filtration unit.

[0064] In one specific embodiment, a coagulation and sedimentation unit 008 is further included, disposed before the electrodialysis unit. The coagulation and sedimentation unit includes a first wastewater inlet and a first wastewater outlet, the first wastewater outlet being connected to the wastewater inlet of the electrodialysis unit. It is understood that the coagulation and sedimentation unit is used to reduce particulate matter and color in the wastewater. Exemplarily, the coagulation and sedimentation unit includes polyaluminum chloride ([Al2(OH)2]). n Cl 6-n ] m (m≤10, n=1-5).

[0065] In one specific embodiment, a phosphate removal unit 009 is also included. This phosphate removal unit includes a first purified water inlet, a calcium salt inlet, and a first purified water outlet. The first purified water inlet is connected to the purified water outlet of the advanced oxidation unit. It can be understood that after step a, phosphate and bicarbonate ions still exist in the acidic and alkaline water. After steps b and c, organic pollutants decompose to generate small molecule phosphate ions. Therefore, the purpose of this embodiment in setting up the phosphate removal unit is to further remove impurities such as phosphate ions and / or bicarbonate ions after the removal of organic pollutants from the wastewater by this invention.

[0066] The present invention will be described in detail below with reference to specific embodiments:

[0067] Example 1

[0068] This example provides a device for removing organic pollutants from wastewater, combined with... Figure 1The device includes: an electrodialysis unit 001, a phosphate and bicarbonate removal unit 002, and an advanced oxidation unit 003; the electrodialysis unit includes a wastewater inlet, a neutral water outlet, an acidic water outlet, and a first alkaline water outlet; the phosphate and bicarbonate removal unit includes a first alkaline water inlet, a calcium chloride inlet, and a second alkaline water outlet; the advanced oxidation unit includes a neutral water inlet, an acidic water inlet, a second alkaline water inlet, an oxidant inlet, and a purified water outlet;

[0069] The first alkaline water outlet is connected to the first alkaline water inlet via the first pipe 004, the second alkaline water outlet is connected to the second alkaline water inlet via the second pipe 005, the neutral water outlet is connected to the neutral water inlet via the third pipe 006, and the acidic water outlet is connected to the acidic water inlet via the fourth pipe 007; each of the first, second, third, and fourth pipes is equipped with a check valve and a flow control valve.

[0070] Comparative Example 1

[0071] This example provides an apparatus for removing organic pollutants from wastewater. The apparatus includes only an advanced oxidation unit identical to that in Example 1, which includes a wastewater inlet, an oxidant inlet, and a purified water outlet.

[0072] Comparative Example 2

[0073] This example provides an apparatus for removing organic pollutants from wastewater. The apparatus includes only a phosphate and bicarbonate removal unit and an advanced oxidation unit, which are the same as those in Example 1. The phosphate and bicarbonate removal unit includes a first wastewater inlet, a calcium salt inlet, and a first wastewater outlet. The advanced oxidation unit includes a second wastewater inlet, an oxidant inlet, and a purified water outlet.

[0074] The first wastewater outlet is connected to the second wastewater inlet via a pipeline, and both pipelines are equipped with check valves and flow control valves.

[0075] Experimental Example 1

[0076] This example utilizes the apparatus provided in Example 1 to remove organic pollutants from wastewater. The wastewater in this example has a COD concentration of 200–300 mg / L, with phenol being the main organic pollutant in molecular form, and phosphate and bicarbonate concentrations of 5 mg / L and 110 mg / L, respectively. The method includes the following steps:

[0077] S1. The wastewater to be treated enters the electrodialysis unit 001 through the wastewater inlet. After treatment, it is divided into three parts: one part is neutral water, one part is acidic water containing cations, and the other part is alkaline water containing anions.

[0078] S2. Adjust the flow control valves of the first pipe 004, the third pipe 006, and the fourth pipe 007 so that the liquid flow rate of the first pipe 004 and the fourth pipe 007 is 0, while the liquid flows normally through the third pipe 006. Neutral water enters the advanced oxidation unit 003 through the third pipe 006, and the oxidant is introduced from the oxidant inlet. Fe... 2+ The dosage is 300 mg / L, hydrogen peroxide and Fe 2+ With a molar ratio of 2:1, the oxidant and neutral water come into contact and react to obtain purified water;

[0079] After 1 hour of treatment, the removal efficiencies of phosphate and bicarbonate were 99% and 100%, respectively, and the COD of the purified water effluent was less than 50 mg / L.

[0080] Comparative Test Example 1

[0081] This example utilizes the apparatus provided in Comparative Example 1 to remove organic pollutants from wastewater. The wastewater in this example has a COD concentration of 200–300 mg / L, with phenol being the main organic pollutant in molecular form, and phosphate and bicarbonate concentrations of 5 mg / L and 110 mg / L, respectively. The method includes the following steps:

[0082] Wastewater enters the advanced oxidation unit through the wastewater inlet, and the oxidant is introduced through the oxidant inlet, wherein Fe... 2+ The dosage is 300 mg / L, hydrogen peroxide and Fe 2+ With a molar ratio of 2:1, the oxidant and neutral water come into contact and react to obtain purified water;

[0083] After 1 hour of treatment, the COD of the purified water effluent was 90-130 mg / L.

[0084] Comparative Test Example 1-1

[0085] This example utilizes the apparatus provided in Comparative Example 2 to remove organic pollutants from wastewater. The wastewater in this example has a COD concentration of 200–300 mg / L, with phenol being the main organic pollutant in molecular form, and phosphate and bicarbonate concentrations of 5 mg / L and 110 mg / L, respectively. The method includes the following steps:

[0086] Wastewater enters the phosphate and bicarbonate removal unit through the first wastewater inlet. Simultaneously, calcium chloride is added through the calcium chloride inlet to adjust the pH to 10-11. The bicarbonate, phosphate, and calcium chloride in the water react, forming precipitates and pre-purified wastewater. This pre-purified wastewater, after being adjusted to neutral pH, enters the advanced oxidation unit through the second wastewater inlet. The oxidant is added through the oxidant inlet, where Fe... 2+ The dosage is 300 mg / L, hydrogen peroxide and Fe 2+With a molar ratio of 2:1, the oxidant and neutral water come into contact and react to obtain purified water;

[0087] After 1 hour of treatment, the COD of the purified water effluent is 80-100 mg / L.

[0088] Experimental Example 2

[0089] This example utilizes the apparatus provided in Example 1 to remove organic pollutants from wastewater. The wastewater to be treated in this example has a COD concentration of 1200–300 mg / L, with glyphosate as the main organic pollutant, and phosphate and bicarbonate concentrations of 80 mg / L and 130 mg / L, respectively. The method includes the following steps:

[0090] S1. The wastewater to be treated enters the electrodialysis unit 001 through the wastewater inlet. After electrodialysis treatment, it is divided into three parts: one part is neutral water, one part is acidic water containing cations, and the other part is alkaline water containing anions.

[0091] S2. Adjust the flow control valves of the first pipe 004, the second pipe 005, the third pipe 006, and the fourth pipe 007 to ensure normal liquid flow. Alkaline water flows into the phosphate and bicarbonate removal unit 002 through the first pipe 004. Calcium salt is introduced through the calcium salt inlet, and the bicarbonate in the alkaline water becomes carbonate. The carbonate, phosphate, and calcium salts come into contact and react to form precipitate and pre-purified alkaline water. The pre-purified alkaline water flows into the advanced oxidation unit 003 through the second pipe 005. Neutral water and acidic water flow into the advanced oxidation unit 003 through the third pipe 006 and the fourth pipe 007, respectively. The oxidant is introduced through the oxidant inlet, wherein Fe... 2+ The dosage is 700 mg / L, hydrogen peroxide and Fe 2+ With a molar ratio of 2:1, the oxidant and neutral water come into contact and react to obtain purified water;

[0092] After 1 hour of treatment, the removal efficiencies of phosphate and bicarbonate were 98% and 100%, respectively, and the COD of the purified water effluent was 200-500 mg / L.

[0093] Comparative Test Example 2

[0094] This example utilizes the apparatus provided in Comparative Example 1 to remove organic pollutants from wastewater. The wastewater to be treated in this example has a COD concentration of 1200–300 mg / L, with glyphosate as the main organic pollutant, and phosphate and bicarbonate concentrations of 80 mg / L and 130 mg / L, respectively. The method includes the following steps:

[0095] Wastewater enters the advanced oxidation unit through the wastewater inlet, and the oxidant is introduced through the oxidant inlet, wherein Fe... 2+The dosage is 700 mg / L, hydrogen peroxide and Fe 2+ With a molar ratio of 2:1, the oxidant and neutral water come into contact and react to obtain purified water;

[0096] After 1 hour of treatment, the COD of the purified water effluent was 700-1800 mg / L, and the phosphate removal rate was 60%-65%.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for removing organic pollutants from wastewater, characterized in that, Includes the following steps: S1. The wastewater to be treated is divided into three parts by electrodialysis: one part is neutral water, one part is acidic water containing cations, and the other part is alkaline water containing anions. S2. Perform any one of the following steps: a, b, or c Step a: When organic pollutants are only present in the neutral water, the neutral water and oxidant are directly mixed and stirred to remove the organic pollutants and obtain purified water; Step b: When organic pollutants are present simultaneously in neutral water, acidic water, and alkaline water, calcium salt is added to the alkaline water. 2+ The organic pollutants react with phosphate and carbonate to form precipitates, and the solid and liquid are separated to obtain pre-purified alkaline water. Acidic water, neutral water, pre-purified alkaline water and oxidant are mixed and stirred to remove the organic pollutants and obtain purified water. Step c: When organic pollutants are present in both acidic and alkaline water, calcium salt is added to the alkaline water. 2+ The solution reacts with phosphate and carbonate ions to form precipitates, and the solid and liquid are separated to obtain pre-purified alkaline water. The acidic water, the pre-purified alkaline water, and the oxidant are mixed and stirred to remove the organic pollutants and obtain purified water.

2. The method according to claim 1, characterized in that, The oxidant includes hydrogen peroxide and Fe. 2+ .

3. The method according to claim 2, characterized in that, The hydrogen peroxide and Fe 2+ The molar ratio is 2:

1.

4. The method according to claim 1, characterized in that, The wastewater to be treated undergoes coagulation and sedimentation treatment before step S1.

5. The method according to claim 1, characterized in that, After obtaining purified water in step a, you should also The process includes the following steps: mixing purified water and alkaline water, adding calcium salts, and Ca... 2+ After reacting with phosphate and carbonate ions to form precipitates, solid-liquid separation occurs. After obtaining purified water in step b, The process includes the following steps: The purified water is further treated by electrodialysis and divided into three parts: neutral water, acidic water containing cations, and alkaline water containing anions. Calcium salts (Ca) are then added to the alkaline water. 2+ It reacts with phosphate and carbonate ions to form precipitates, resulting in solid-liquid separation; After obtaining purified water in step c, The process includes the following steps: Purified water and neutral water are mixed, and then the mixture is further treated by electrodialysis to divide it into three parts: one part is neutral water, one part is acidic water containing cations, and the other part is alkaline water containing anions. Ca is then added to the alkaline water. 2+ Ca 2+ It reacts with phosphate and carbonate ions to form precipitates, thus separating the solid and liquid phases.

6. An apparatus for removing organic pollutants from wastewater, characterized in that, It includes an electrodialysis unit, a phosphate and bicarbonate removal unit, and an advanced oxidation unit; the electrodialysis unit includes a wastewater inlet, a neutral water outlet, an acidic water outlet, and a first alkaline water outlet; the phosphate and bicarbonate removal unit includes a first alkaline water inlet, a calcium salt inlet, and a second alkaline water outlet; the advanced oxidation unit includes a neutral water inlet, an acidic water inlet, a second alkaline water inlet, an oxidant inlet, and a purified water outlet; The first alkaline water outlet is connected to the first alkaline water inlet via a first pipe, the second alkaline water outlet is connected to the second alkaline water inlet via a second pipe, the neutral water outlet is connected to the neutral water inlet via a third pipe, and the acidic water outlet is connected to the acidic water inlet via a fourth pipe; each of the first, second, third, and fourth pipes is equipped with a check valve and a flow control valve.

7. The apparatus according to claim 6, characterized in that, It also includes a filtration unit, which is located inside the phosphate and bicarbonate removal unit. After passing through the filtration unit, alkaline water flows out from the second alkaline water outlet.

8. The apparatus according to claim 7, characterized in that, It also includes a coagulation and sedimentation unit, located before the electrodialysis unit. The coagulation and sedimentation unit includes a first wastewater inlet and a first wastewater outlet, and the first wastewater outlet is connected to the wastewater inlet of the electrodialysis unit.

9. The apparatus according to claim 7, characterized in that, The phosphate and bicarbonate removal unit also includes a solids outlet.

10. The apparatus according to claim 6, characterized in that, It also includes a phosphate removal unit, which includes a first purified water inlet, a calcium salt inlet, and a first purified water outlet, wherein the first purified water inlet and the purified water outlet of the advanced oxidation unit are connected.

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