Sewage treatment system based on electrochemical spontaneous magnetic flocculation and operation method and application thereof

Abstract

The application provides a sewage treatment system based on electrochemical spontaneous magnetic flocculation and an operation method and application thereof, and relates to the technical field of sewage treatment.The sewage treatment system comprises a flocculation zone and an aeration zone.The flocculation zone is provided with a reaction tank for electrocoagulation reaction.The anode of the reaction tank is used for generating iron ion species in the electrocoagulation reaction.The cathode of the reaction tank is used for generating oxidizing species in the electrocoagulation reaction.The aeration zone is used for providing oxygen for the cathode to generate oxidizing species, and simultaneously fully mixing the iron ion flocculant, the magnetic iron species and the sewage.The application solves the technical problems of the existing flocculation magnetic separation wastewater treatment technology, such as difficulty in controlling the flocculant dosage, complicated operation of recovering the magnetic seeds, high cost of adding the reagent and loss of the magnetic seed recovery, and achieves the technical effect of controlling the flocculation reaction through electrocoagulation, and part of the iron species is simultaneously oxidized into magnetic species to carry the flocculation body to quickly sink.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, and particularly relates to a sewage treatment system based on electrochemical spontaneous magnetic flocculation and an operation method and application thereof. BACKGROUND

[0002] According to the properties of heavy metal wastewater, traditional treatment methods include ion exchange method, biological method, chemical precipitation method and membrane separation method, etc., and these methods have problems of high operation cost and secondary pollution.

[0003] Organic wastewater is a kind of wastewater which is greater threat to environmental pollution and human health, and is produced in the industrial processes such as printing and dyeing and chemical industry, and directly discharged into water will cause the consumption of dissolved oxygen in water and affect the growth of aquatic organisms. Traditional treatment methods include biological method and adsorption method, etc., but have defects of poor wastewater treatment stability and long treatment period.

[0004] Flocculation method has been widely applied due to its strong treatment capacity, low energy consumption and stable purification effect. In a narrow sense, flocculation refers to the process of aggregation and growth of particles in an aqueous dispersion system under the action of chemicals. The electrocoagulation process avoids the problem of adding flocculants and is an ideal process for treating heavy metal wastewater and organic wastewater.

[0005] The electrocoagulation process uses iron (Fe) and aluminum (Al) as anodes, and generates Al and Fe ions under the action of electric current, and a series of hydrolysis, polymerization and oxidation processes of ferrous iron in water form various hydroxyl complexes, polynuclear hydroxyl complexes and hydroxides, which can quickly separate suspended solids and colloids in water, and have good removal effect on soluble COD and total phosphorus; compared with traditional processes, the electrocoagulation process has advantages of small occupation, low investment, good treatment effect and high automation degree.

[0006] Magnetic separation is a kind of rapid treatment process developed on the basis of flocculation method, and magnetic powder is added in the ordinary flocculation process, the magnetic powder combines with the surrounding flocs through magnetic action, so that the flocs are quickly enlarged, thereby increasing the settling velocity of the original flocs; the magnetic separation process is widely applied to various sewage treatment equipment due to its characteristics of small occupation and fast treatment rate.

[0007] The operation of the traditional flocculation and magnetic separation device system needs to add coagulants and flocculants, the commonly used coagulants include polyaluminum chloride and polyferric sulfate, and the commonly used flocculants are polyacrylamide, which can be divided into anionic, cationic and non-ionic types. Since the total amount of wastewater treatment is large, the amount of coagulants and flocculants is usually large, which is one of the main costs of process operation. In addition, the steps of adding magnetic seeds and separating magnetic seeds also cause cumbersome work, and the process also loses part of the magnetic seed material, thereby increasing the cost of wastewater treatment.

[0008] The pollutants in different wastewater are different, and the concentrations of the pollutants are different, so in the actual flocculation process, the amount of coagulant and flocculant needs to be adjusted according to the quality of wastewater, but it is difficult to grasp in actual work. According to statistics, the cost of the amount of added reagent accounts for about 50% of the total cost, so reducing the cost of reagent addition will greatly improve the economy of flocculation technology.

[0009] Therefore, the present application is proposed. SUMMARY

[0010] One of the purposes of the present application is to provide a wastewater treatment system based on electrochemical spontaneous magnetic flocculation, which solves the problems of complicated magnetic seed recovery, long ferromagnetic distance and slow flocculation body sinking in the magnetic separation wastewater treatment process, and can control the flocculation reaction by electrocoagulation, so as to achieve the effect of part of the iron species being oxidized into magnetic species at the same time and carrying the flocculation body to sink quickly.

[0011] The second purpose of the present application is to provide an operation method of the wastewater treatment system based on electrochemical spontaneous magnetic flocculation, which does not need to add coagulant, can produce magnetic material and combine with flocculation body, so as to accelerate the growth and settlement of flocculation body, and make the utilization of effective components more sufficient.

[0012] The third purpose of the present application is to provide an application of the wastewater treatment system based on electrochemical spontaneous magnetic flocculation, which has the characteristics of good stability and strong adaptability, can withstand greater changes of water quality and water quantity, and can effectively treat organic printing and dyeing wastewater and heavy metal industrial wastewater.

[0013] In order to achieve the above purposes of the present application, the following technical solutions are adopted:

[0014] In a first aspect, a wastewater treatment system based on electrochemical spontaneous magnetic flocculation includes a flocculation zone and an aeration zone.

[0015] The flocculation zone is provided with a reaction tank for electrocoagulation reaction.

[0016] The anode of the reaction tank is used to produce iron ion species in the electrocoagulation reaction.

[0017] The cathode of the reaction tank is used to produce oxidizing species in the electrocoagulation reaction.

[0018] The aeration zone is used to provide oxygen for the cathode to react to generate oxidizing species, and to fully mix iron ion flocculant, magnetic iron species and wastewater.

[0019] Further, the anode of the reaction tank includes iron metal.

[0020] Further, the cathode of the reaction tank includes carbon felt doped with FeOCl.

[0021] The oxidizing species includes hydrogen peroxide.

[0022] Further, the anode and the cathode of the reaction tank are oppositely arranged.

[0023] The anode and the cathode are connected by a unipolar and / or a bipolar.

[0024] The distance between the anode and the cathode is 1cm-5cm.

[0025] Further, the aeration zone comprises an aeration device.

[0026] The aeration device is provided with a microporous aeration device, a sludge discharge port at the bottom and a water outlet at the sidewall.

[0027] The second aspect is a method for operating the sewage treatment system as described in any one of the preceding aspects, comprising the following steps:

[0028] The sewage is delivered into the reaction tank, the pulse current is turned on for the electrocoagulation reaction, the iron ion species is generated at the anode and the oxidizing species is generated at the cathode, the aeration zone is aerated, part of the iron ion species is used as a flocculant to contact the sewage for flocculation, the other part of the iron ion species reacts with the oxidizing species to be oxidized into magnetic iron species, the magnetic iron species is combined with the flocculating body through magnetism, and the flocculating body is separated from the water after being enlarged.

[0029] Further, the density of the pulse current is 1A / cm 2 -10A / cm 2 .

[0030] The duty cycle of the pulse current is 0.1-0.9.

[0031] Further, the electrocoagulation reaction time is 10min-120min.

[0032] Further, the conductivity of the sewage is 500μs / cm 3 above.

[0033] The third aspect is the application of the sewage treatment system as described in any one of the preceding aspects in the treatment of heavy metal wastewater and organic wastewater.

[0034] Compared with the prior art, the present application has at least the following beneficial effects:

[0035] The sewage treatment system based on electrochemical spontaneous magnetic flocculation provided by the application can control flocculation reaction through electroflocculation, achieves the effect that part of iron species is oxidized into magnetic species to carry flocculation bodies to quickly sink, specifically, iron ions are generated through anode oxidation reaction under an external current, oxidizing species are generated at the cathode, part of the iron ions develop into hydroxyl complexes, polynuclear hydroxyl complexes and hydroxides and other iron ion flocculation bodies through a series of hydrolysis and polymerization reactions, another part of the iron ions is oxidized into magnetic iron species through reaction with the oxidizing species, the magnetic field with the magnetic material as the center is generated, pollutants and flocculation bodies around the magnetic field quickly gather to the magnetic material under the interaction of Lorentz force, Van der Waals force and hydrogen bonds, the flocculation bodies quickly grow with the magnetic material as the center, which forms flocculation bodies with larger size and compact structure, and the density difference with water is larger, and the flocculation bodies are more easily separated from water, and the formed flocculation bodies have magnetism and can be easily separated through magnetic separation technology; in general, the application simplifies the complexity of the equipment, the whole system has small floor space, and has good separation effect, and the water quality after treatment is obviously improved.

[0036] The operation method of the sewage treatment system based on electrochemical spontaneous magnetic flocculation provided by the application does not need to add coagulants, can produce magnetic materials and flocculation bodies to combine, thereby accelerating the growth and settlement of the flocculation bodies, and makes the utilization of effective components more sufficient.

[0037] The application of the sewage treatment system based on electrochemical spontaneous magnetic flocculation provided by the application has the characteristics of good stability and strong adaptability, can withstand greater changes of water quality and water volume, and can effectively treat organic printing and dyeing wastewater and heavy metal industrial wastewater. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0039] Figure 1 The principle schematic diagram of the magnetic flocculation process provided by one embodiment of the application is shown in the figure;

[0040] Figure 2 The principle schematic diagram of the electroflocculation process provided by one embodiment of the application is shown in the figure;

[0041] Figure 3 The effect diagram of the influence of the initial pH obtained in test example 1 of the application on the flocculation and decolorization effect is shown in the figure;

[0042] Figure 4Figure for effect of initial pH obtained from test example 1 of the present application on COD removal rate;

[0043] Figure 5 Figure for effect of current density obtained from test example 1 of the present application on decolorization efficiency;

[0044] Figure 6 Figure for effect of electrode plate spacing obtained from test example 1 of the present application on decolorization efficiency;

[0045] Figure 7 Figure for effect of removal efficiency of heavy metals obtained from test example 2 of the present application;

[0046] Figure 8 Figure for effect of removal rate of heavy metals after multiple cycles obtained from test example 2 of the present application. DETAILED DESCRIPTION

[0047] The technical solutions of the present application will be described in detail below with examples. Obviously, the described examples are part of the embodiments of the present application, rather than all the embodiments. Based on the examples in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0048] According to the first aspect of the present application, a wastewater treatment system based on electrochemical spontaneous magnetic flocculation is provided, comprising a flocculation zone and an aeration zone;

[0049] The flocculation zone is provided with a reaction tank for electrocoagulation reaction;

[0050] The anode of the reaction tank is used for generating iron ion species in the electrocoagulation reaction;

[0051] The cathode of the reaction tank is used for generating oxidizing species in the electrocoagulation reaction;

[0052] The aeration zone is used for providing oxygen for the cathode to generate oxidizing species, and at the same time, fully mixing the iron ion flocculant, magnetic iron species and wastewater.

[0053] The system of the present application integrates electrocoagulation and magnetic flocculation, and the reaction tank in the flocculation zone is respectively provided with an anode for realizing electrocoagulation by dissolution under the action of current and a cathode with oxygen reduction active sites. At the same time, an aeration zone is provided near the cathode.

[0054] In the present application, iron ions are generated by anodic oxidation reaction through an applied current, and oxidizing species are generated at the cathode. A part of the iron ions develops into iron ion flocculation such as hydroxyl complex, polynuclear hydroxyl complex and hydroxide through a series of hydrolysis and polymerization reactions. Another part of the iron ions is oxidized into magnetic iron species by reacting with the oxidizing species. The magnetic iron species generates a magnetic field with magnetic material as the center. Pollutants and flocculation around the magnetic field quickly gather to the magnetic material under the interaction of Lorentz force, Van der Waals force and hydrogen bond. The flocculation grows rapidly with the magnetic material as the center, which forms flocculation with larger size and compact structure, and the density difference with water is larger, so the flocculation is easier to separate from water. Meanwhile, the formed flocculation is magnetic, which can be easily separated by magnetic separation technology.

[0055] In summary, the present application simplifies the complexity of the equipment, the entire system occupies a small area, and the separation effect is good, and the water quality after treatment is obviously improved.

[0056] In a preferred embodiment, the anode of the reaction tank includes but is not limited to iron metal.

[0057] In the present application, the anode of the reaction tank can use a plate electrode such as an iron plate, because the plate electrode has a larger surface area, and the flocculation ions (iron ion species) generated under the action of current can be widely distributed in the solution, which is conducive to improving the generation efficiency of the flocculation. The electrode can also use a plate electrode, which can generate more magnetic materials connecting each flocculation, which is conducive to the agglomeration between the flocculations.

[0058] It should be noted that the flocculation is composed of flocculants, pollutants and magnetic materials, and each flocculation and magnetic material is separated and settled out by the combined action of gravity and magnetism.

[0059] In the present application, the electrocoagulation reaction can be carried out by pulse current, and an iron plate is used as the anode. The anode corrodes under the condition of power supply to generate iron ion species. On the one hand, the iron ion species has flocculation effect, and on the other hand, the iron ion species can react with the oxidizing species generated at the cathode to be oxidized into magnetic iron species such as magnetic iron oxide and magnetite. The small flocculation in sewage sludge combines with the magnetic iron species and is separated and settled out.

[0060] In a preferred embodiment, the cathode of the reaction tank includes but is not limited to carbon felt doped with FeOCl. The carbon felt doped with FeOCl (iron oxygen chloride) is used as the cathode, and the generated oxidizing species includes but is not limited to hydrogen peroxide (H2O2).

[0061] It should be noted that the cathode reduces oxygen to hydrogen peroxide (H2O2), and the hydrogen peroxide generates strong oxidizing active substances to oxidize the iron ion species generated at the anode into magnetic iron species.

[0062] In a preferred embodiment, the reaction tank is provided with electrode clamping grooves and electrode supporting bottom, two electrode clamping grooves are located on two opposite surfaces of the reaction tank, the dissoluble iron metal electrode, i.e. anode, is placed in the electrode clamping grooves under the action of current and is supported by the electrode supporting bottom, and the anode and the cathode are oppositely arranged.

[0063] In the present application, the anode and the cathode can be connected by monopole and / or multipole, and the distance between the anode and the cathode can be 1 cm-5 cm, for example, 1 cm, 2 cm, 3 cm, 4 cm or 5 cm, and the distance between the electrodes should not be too far to ensure that the iron ions generated by the electrodes can generate flocculation bodies with the pollutants to be precipitated in the sewage and interact with the magnetic substances.

[0064] In a preferred embodiment, the aeration zone is provided with an aeration device, the aeration device can be provided with a microporous aeration device, the bottom can be provided with a sludge discharge port, and the sidewall can be provided with a water outlet.

[0065] The aeration device provides sufficient oxygen for the cathode reaction, and fully mixes the generated iron ion flocculants, magnetic iron species and sewage.

[0066] In the present application, the sewage treated by the system is self-settled to separate sludge flocculation bodies and supernatant, the supernatant with removed pollutants can be discharged from the water outlet, and the generated sludge can be regularly discharged from the bottom of the electroflocculation device.

[0067] According to a second aspect of the present application, there is provided a method for operating the sewage treatment system according to any one of the above, comprising the following steps:

[0068] The sewage is transported into the reaction tank, the pulse current is turned on to perform electroflocculation reaction, the anode generates iron ion species, the cathode generates oxidizing species, the aeration zone is aerated, a part of the iron ion species is used as flocculants to contact and flocculate the sewage, another part of the iron ion species is oxidized into magnetic iron species by reacting with the oxidizing species, the magnetic iron species is combined with the flocculation bodies through magnetism, and the flocculation bodies are separated from the sewage after increasing.

[0069] The method for operating the sewage treatment system based on electrochemical spontaneous magnetic flocculation provided by the present application does not need to add coagulants, can self-produce magnetic substances to combine with flocculation bodies, thereby accelerating the growth and settlement of the flocculation bodies and making the utilization of effective components more sufficient.

[0070] The principle diagram of the magnetic flocculation process of the operating method of the present application is shown in Figure 1 , and the principle diagram of the electroflocculation process is shown in Figure 2Specifically, first, flocculation treatment is performed, the reaction tank is opened by power supply control, and soluble iron electrode dissolution generates flocculants in the reaction tank. Meanwhile, the aeration device is controlled to be opened to ensure sufficient dissolved oxygen in the water body, so that hydrogen peroxide is generated at the cathode with oxygen reduction activity. Part of the generated hydrogen peroxide is catalytically formed into hydroxyl radicals with strong oxidation ability. Subsequently, the iron complex in the wastewater is partially oxidized into magnetic substances by controlling the pulse current time. The flocculation bodies and magnetic substances in the wastewater are relatively dispersed, increasing the possibility of contact with pollutants. Then, each flocculation body and magnetic substance are combined by magnetism to be quickly separated out by sedimentation.

[0071] It should be noted that the oxidation products or reduction products generated by the pulse current electrode have pulse interval characteristics. The generated iron ions for flocculation are relatively interval flocculation reactions, and the solution shows a large number of dispersed flocculation bodies. The dispersed magnetic species are generated at the cathode with pulse interval. The two phases can more fully remove impurities in the water. Some pollutants have charges in the water. Pollutants or flocculation bodies with the same charge have repulsive forces to maintain stability. The partial pollutants are destabilized and aggregated in the electrode neutralization. In addition, the anode oxidation and cathode reduction on the electrode can remove part of the pollutants.

[0072] A typical operation method of a wastewater treatment system based on electrochemical spontaneous magnetic flocculation includes the following steps:

[0073] (1) The wastewater to be treated is delivered to the reaction tank for electrocoagulation reaction, and the reaction tank is opened by a power supply control module;

[0074] It should be noted that the wastewater to be treated can be filtered to remove impurities before entering the electrocoagulation reaction tank. Filtration can trap large impurities to avoid adverse effects on subsequent devices;

[0075] (2) Electrocoagulation reaction is performed by using pulse current, and iron ion species (ferrous ions) are generated at the anode, and oxidizing species, i.e. hydrogen peroxide (H2O2), are generated at the cathode;

[0076] The iron ion species (ferrous ions) are obtained from the electrolytic iron electrode plate in the electrocoagulation. The amount of ferrous ions can be adjusted according to the concentration of pollutants in the wastewater. The oxidizing species can be controlled by adjusting the size of the applied current and the aeration amount of the cathode area;

[0077] It should be noted that the anode corrosion generates ferrous hydroxide under alkaline conditions, and further changes into ferric hydroxide under oxidation conditions. Fe3O4 and γ-Fe3O4 are typical magnetic substances. The cathode generates hydroxyl radicals with stronger oxidation ability, and part of the ferrous hydroxide and other iron species are oxidized into magnetic substances;

[0078] (3) Turn on the aeration device, make the flocculants and sewage fully contact, combine the anode zone species and the cathode zone species, oxidize part of the iron salt into magnetic iron oxide, and form magnetic iron species;

[0079] It should be noted that the necessary condition for oxygen reduction at the cathode is sufficient aeration, which enables the species in the sewage to be uniformly dispersed, the magnetic material and the flocculating body generated by electroflocculation to be combined, and the core of the flocculating body to be dispersed to contact more aggregating materials, so that the flocculating body is easy to combine with the magnetic material and aggregate while being large, and the flocculating body is easy to settle;

[0080] (4) After the reaction in step (3), the flocculating body is more likely to aggregate and settle, the flocculating body is separated from the sewage, the sewage from which the pollutants are removed is discharged from the water outlet, and the sludge is separated from the electroflocculation equipment at the bottom.

[0081] The operation method of the present application does not need to add flocculants and magnetic species, the reaction efficiency of electrochemically generated flocculants (iron ion species) is more than 3 times that of external reagents, and the self-produced magnetic iron species can quickly combine with the small flocculating body in the sewage, so that the effective ingredient is more fully utilized, and the addition amount of the coagulant is also reduced, so that the process is more environmentally friendly.

[0082] In a preferred embodiment, the density of the pulse current can be 1A / cm 2 -10A / cm 2 , for example, the typical but non-limiting density is, for example, 1A / cm 2 , 2A / cm 2 , 3A / cm 2 , 4A / cm 2 , 5A / cm 2 , 6A / cm 2 , 7A / cm 2 , 8A / cm 2 , 9A / cm 2 , 10A / cm 2 .

[0083] A higher pulse current density can accelerate the anode reaction and the cathode reaction, which is beneficial to generate more flocculating bodies and magnetic materials, thereby ensuring sufficient flocculation reaction and settling efficiency.

[0084] In the present application, the duty cycle (high level duration / pulse cycle time) of the pulse current can be 0.1-0.9, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, but is not limited thereto, and a suitable duty cycle is beneficial to the ions generated each time to fully interact with the impurities in the solution, be isolated and separated from each other, and be more widely distributed in the wastewater, which is beneficial to reducing the electrolysis energy consumption and saving the wastewater treatment cost.

[0085] In a preferred embodiment, the electrocoagulation reaction time can be 10 min-120 min, and a typical but non-limiting time is, for example, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min.

[0086] In a preferred embodiment, the conductivity of the sewage can be 500 μs / cm 3 In the above, if the conductivity of the sewage is low, electrolytes such as sodium sulfate and sodium chloride need to be added to increase the conductivity of the solution, so that the sewage has higher efficiency in electrocoagulation.

[0087] According to a third aspect of the present application, there is provided an application of the sewage treatment system of any one of the above in heavy metal wastewater treatment and organic wastewater treatment.

[0088] The application of the sewage treatment system based on electrochemical spontaneous magnetic flocculation provided by the present application has the characteristics of good stability and strong adaptability, can withstand greater changes in water quality and water quantity, and can effectively treat organic printing and dyeing wastewater and heavy metal industrial wastewater.

[0089] The present application will be further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0090] Example 1

[0091] A sewage treatment system based on electrochemical spontaneous magnetic flocculation, comprising a flocculation zone and an aeration zone;

[0092] The flocculation zone is provided with a reaction tank for electrocoagulation reaction, and the reaction tank is a rectangular reaction tank with a size of 1 m in length, 0.8 m in width, and 0.8 m in depth;

[0093] The anode of the reaction tank is used to generate iron ion species in the electrocoagulation reaction, and the anode is an iron plate with a size of 1 m in length and 0.5 m in width;

[0094] The cathode of the reaction tank is used to generate oxidizing species (hydrogen peroxide) in the electrocoagulation reaction, and the cathode is a carbon felt doped with FeOCl with the same size as the anode;

[0095] The anode and the cathode of the reaction tank are oppositely arranged, and the anode and the cathode are fixed on the two sides of the reaction tank by an insulating material to ensure good insulation between the electrodes and the tank wall, and the anode and the cathode are connected by a single pole and / or a multiple pole;

[0096] The aeration zone is used to provide oxygen for the cathode to react to generate oxidizing species, while the iron ion flocculant, magnetic iron species and sewage are fully mixed;

[0097] The aeration zone is provided with an aeration device, the aeration device is provided with a microporous aeration device, the bottom is provided with a sludge discharge port, and the side wall is provided with a water outlet.

[0098] Example 2

[0099] The embodiment is a running method of the sewage treatment system based on electrochemical spontaneous magnetic flocculation of example 1, comprising the following steps:

[0100] (1) The sewage to be treated is transported to the reaction tank for electrocoagulation reaction, and the reaction tank is controlled to be opened by the power supply control module;

[0101] The sewage to be treated is collected, filtered to remove impurities, and then enters the reaction tank for electrocoagulation, which uses filtration to retain large impurities and avoids their entry into the subsequent device to produce adverse effects;

[0102] (2) The pulse current is used for electrocoagulation reaction, the anode generates iron ion species (ferric ion), and the cathode generates oxidizing species, i.e. hydrogen peroxide (H2O2);

[0103] The iron ion species (ferric ion) is obtained from the electrolytic iron plate in the electrocoagulation, and the amount of ferric ion can be adjusted according to the concentration of pollutants in the sewage, and the oxidizing species can be controlled by adjusting the size of the applied current and the aeration amount of the cathode zone;

[0104] The anode generates ferrous hydroxide under alkaline conditions, and further becomes ferric hydroxide under oxidation conditions, Fe3O4 and γ-Fe3O4 are typical magnetic materials, and the cathode generates hydroxyl radicals with stronger oxidation ability, which partially oxidize the iron species such as ferrous hydroxide into magnetic materials;

[0105] (3) The aeration device is opened, the flocculant and the sewage are fully contacted, the anode zone species and the cathode zone species are combined, part of the iron salt is oxidized into magnetic iron oxide, and the magnetic iron species is formed;

[0106] The necessary condition for the cathode to occur oxygen reduction is sufficient aeration, which makes the species in the sewage be uniformly dispersed, the magnetic material and the flocculating body generated by electrocoagulation are combined, especially the core of the flocculating body can be dispersed to contact more aggregating materials, so that the flocculating body becomes larger and easier to combine with the magnetic material, and the flocculating body is more aggregated and easy to settle;

[0107] (4) After the reaction of step (3), the flocculating body is more easily aggregated and settled, the flocculating body is separated from the sewage, the sewage from which the pollutants are removed is discharged from the water outlet, and the sludge is separated from the electrocoagulation equipment at the bottom.

[0108] Test Example 1

[0109] Verify the performance of the wastewater treatment system based on electrochemical spontaneous magnetic flocculation of Example 1:

[0110] The processing object is printing and dyeing organic wastewater, with a chemical oxygen demand (COD) of 500 mg / L and a dye concentration of 800 mg / L;

[0111] The printing and dyeing organic wastewater is transported to the electrocoagulation reaction tank by the pumping system at a flow rate of 2 m 3 / h for electrocoagulation reaction, and a pulse current is applied to the reaction tank, and the wastewater is continuously stirred to enhance the flocculation effect;

[0112] After the electrocoagulation reaction is completed, the small floc in the wastewater is combined with the magnetic material under the action of gravity and naturally settles to the bottom of the reaction tank. The bottom of the reaction tank is provided with a sludge discharge outlet, and the settled sludge is discharged and collected by a sludge pump;

[0113] Verify the effect of initial pH on flocculation and decolorization, and the results are shown in Figure 3 ;

[0114] Verify the effect of initial pH on COD removal rate, and the results are shown in Figure 4 ;

[0115] Verify the effect of current density on decolorization efficiency, and the results are shown in Figure 5 ;

[0116] Verify the effect of electrode plate spacing on decolorization efficiency, and the results are shown in Figure 6 .

[0117] Test Example 2

[0118] Verify the performance of the wastewater treatment system based on electrochemical spontaneous magnetic flocculation of Example 1:

[0119] The processing object is heavy metal wastewater containing lead, copper, nickel, and hexavalent chromium, with a pH of 6.5, a lead concentration of 48.38 mg / L, a copper concentration of 65.59 mg / L, a chromium concentration of 43.33 mg / L, and a nickel concentration of 1.23 mg / L;

[0120] The heavy metal wastewater is transported to the electrocoagulation reaction tank by the pumping system at a flow rate of 2 m 3 / h for electrocoagulation reaction, and a pulse current is applied to the reaction tank, and the wastewater is continuously stirred to enhance the flocculation effect;

[0121] After the electrocoagulation reaction is completed, the small floc in the wastewater is combined with the magnetic material under the action of gravity and naturally settles to the bottom of the reaction tank. The bottom of the reaction tank is provided with a sludge discharge outlet, and the settled sludge is discharged and collected by a sludge pump,

[0122] The removal efficiency of heavy metals was verified, and the results are shown in Table 2 Figure 7 ;

[0123] The removal rate of heavy metals after multiple cycles was verified, and the results are shown in Table 3 Figure 8 .

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A wastewater treatment system based on electrochemical spontaneous magnetic flocculation, characterized by, The system comprises a flocculation zone and an aeration zone. The flocculation zone is provided with a reaction tank for electrocoagulation reaction. The anode of the reaction tank is used for generating iron ion species in the electrocoagulation reaction. The cathode of the reaction tank is used for generating oxidizing species in the electrocoagulation reaction. The aeration zone is used for providing oxygen for the cathode to generate oxidizing species, and for fully mixing the iron ion flocculant, magnetic iron species and sewage. The cathode of the reaction tank comprises FeOCl-doped carbon felt. The oxidizing species comprises hydrogen peroxide.

2. The sewage treatment system of claim 1, wherein, The anode of the reaction tank comprises iron metal.

3. The sewage treatment system of claim 1, wherein, The anode and the cathode of the reaction tank are oppositely arranged. The anode and the cathode are connected by monopolar and / or bipolar. The distance between the anode and the cathode is 1cm-5cm.

4. The sewage treatment system of claim 1, wherein, The aeration zone comprises an aeration device. The aeration device is provided with a microporous aeration device, a sludge discharge port at the bottom and a water outlet at the sidewall.

5. A method of operating a sewage treatment system as claimed in any one of claims 1 to 4, characterised in that, The system comprises the following steps: The sewage is delivered into the reaction tank, and the electrocoagulation reaction is started by opening the pulse current, the anode generates iron ion species, the cathode generates oxidizing species, the aeration zone is aerated, a part of the iron ion species acts as a flocculant to contact and flocculate the sewage, another part of the iron ion species reacts with the oxidizing species to be oxidized into magnetic iron species, the magnetic iron species combines with the flocculating body through magnetism, the flocculating body increases and is separated from the sewage.

6. The method of operating of claim 5, wherein, The density of the pulsed current is 1 A / cm 2 - 10 A / cm 2 ; The duty cycle of the pulse current is 0.1-0.

9.

7. The method of operating of claim 5, wherein, The electrocoagulation reaction time is 10min-120min.

8. The method of operating of claim 5, wherein, The conductivity of the wastewater is 500 μs / cm 3 The above.

9. The application of the sewage treatment system of any one of claims 1-4 in the treatment of heavy metal wastewater and organic wastewater.

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