A high-efficiency phosphorus and heavy metal removal method for sewage treatment based on electrocoagulation technology

Abstract

This invention relates to the field of wastewater treatment technology, specifically to a highly efficient wastewater treatment method for phosphorus and heavy metal removal based on electrocoagulation technology. The method includes the following steps: introducing wastewater to be treated into an electrocoagulation reaction tank and adjusting the pH; constructing an electrode assembly using a functional anode plate made of composite multimetals and an inert cathode plate, and conducting an electrocoagulation reaction under a direct current electric field; and settling the wastewater after the electrocoagulation reaction to separate and remove the flocs, thereby obtaining purified water. In this invention, the functional anode plate is composed of a composite metal matrix of iron, aluminum, magnesium, and zirconium, which can synergistically generate a richer variety of hydrated metal polymers with better flocculation effects during electrolysis. The organic-inorganic hybrid graft layer constructed on the anode surface by 3-(trihydroxysilyl)propylmethyl phosphate increases the hydrophilicity and active sites of the electrode surface, promoting mass transfer and adsorption of pollutants to the electrode surface.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, in particular to a high-efficiency phosphorus and heavy metal removal method for sewage treatment based on electrocoagulation technology. BACKGROUND

[0002] Electrocoagulation technology is a method of removing pollutants in water by using soluble metal electrodes (such as aluminum or iron) to generate metal ions under the action of an electric field, and generating hydroxide colloids by hydrolysis to adsorb and precipitate, thereby removing pollutants in water; this technology has been widely used in the fields of dyeing wastewater, electroplating wastewater, domestic sewage and industrial wastewater containing phosphorus due to its simple process, easy operation, less reagent addition and good removal effect of phosphorus and heavy metal ions. Chinese invention patent CN114538574B discloses a low-energy consumption and synergistic removal method for phosphorus and heavy metals in dyeing wastewater by electrocoagulation, which comprises the following steps: introducing the concentrated dyeing wastewater to be treated into an electrocoagulation reaction device, adjusting the pH value of the concentrated dyeing wastewater to be treated to 1-7, adding inorganic salt, and performing electrocoagulation treatment under the action of an external direct current electric field, wherein the anode plate of the electrocoagulation reaction device is selected from Fe plate, and the cathode plate is selected from Al plate or Fe plate.

[0003] However, the traditional aluminum / iron anode mainly relies on its hydrolysis products to adsorb and co-precipitate pollutants, and has limited complexing ability for high-concentration phosphate or multivalent heavy metal ions, the treatment effect is greatly affected by pH fluctuation, and the electrode surface is easy to scale, resulting in insufficient long-term operation stability, therefore, we propose a high-efficiency phosphorus and heavy metal removal method for sewage treatment based on electrocoagulation technology. SUMMARY

[0004] The purpose of the present application is to provide a high-efficiency phosphorus and heavy metal removal method for sewage treatment based on electrocoagulation technology, to solve the problem of insufficient long-term operation stability caused by the traditional aluminum / iron anode mainly relying on its hydrolysis products to adsorb and co-precipitate pollutants, and having limited complexing ability for high-concentration phosphate or multivalent heavy metal ions, and the treatment effect being greatly affected by pH fluctuation.

[0005] The present application provides a high-efficiency phosphorus and heavy metal removal method for sewage treatment based on electrocoagulation technology, comprising the following steps:

[0006] S1.1, introducing the sewage to be treated into an electrocoagulation reaction tank and adjusting the pH;

[0007] S1.2, using a functional anode plate prepared by a composite multi-metal composed of iron, magnesium, aluminum and zirconium alloy and an inert cathode plate to form an electrode group, and performing electrocoagulation reaction under the action of a direct current electric field;

[0008] S1.3, the sewage after the electrocoagulation reaction is settled, the flocculation body is separated and removed, and purified water is obtained.

[0009] As preferred, in S1.1, the pH of the sewage to be treated is adjusted to 6.0-7.5 by 0.1 mol / L sodium hydroxide.

[0010] As preferred, in S1.2, the mass percentage of each metal in the composite multi-metal is: iron 40-70%, aluminum 10-30%, magnesium 15-20%, and zirconium 5-10%.

[0011] As preferred, in S1.2, the preparation process of the functional anode plate is as follows:

[0012] The anode substrate is cleaned by ultrasonic cleaning with acetone for 5-10 min to remove oil, then rinsed with ethanol and air dried; the surface is activated by dilute nitric acid for 1-3 min, then rinsed with deionized water and air dried to obtain a pretreated anode substrate;

[0013] 3-(trihydroxysilyl) propyl methyl phosphate is dissolved in deionized water, the pH is adjusted to 4-5 with 0.1 mol / L acetic acid, and stirred at a speed of 300-400 rpm for 20-30 min to obtain a hydrolysis solution;

[0014] The pretreated anode substrate is immersed in the hydrolysis solution and reacted at 40°C for 45-120 min, then dried at 80-120°C for 30-90 min after taking out to obtain a functional anode plate.

[0015] As preferred, the mass concentration of the dilute nitric acid is 0.5-2%.

[0016] As preferred, the molar ratio of the deionized water to 3-(trihydroxysilyl) propyl methyl phosphate is 1:1-3.

[0017] As preferred, the thickness of the functional anode plate graft layer is 20-80 nm.

[0018] As preferred, in S1.2, the inert cathode plate is a titanium plate or a graphite plate.

[0019] As preferred, in S1.2, the current density of the electrocoagulation reaction is 10-30 mA / cm 2 , and the electrolysis time is 15-30 min.

[0020] As preferred, in S1.2, 10-100 mg / L of cationic polyacrylamide is added during the electrocoagulation process.

[0021] Compared with the prior art, the beneficial effects of the present application are:

[0022] In the wastewater treatment method based on the electric flocculation technology, the functional anode plate is composed of a composite metal matrix of iron, aluminum, magnesium and zirconium, which can generate more types of hydrated metal polymers with better flocculation effect during electrolysis, especially the introduction of zirconium greatly enhances the specific complexation and precipitation ability of phosphate, significantly improves the phosphorus removal efficiency and the co-precipitation effect of various heavy metals; the organic-inorganic hybrid graft layer constructed by 3-(trihydroxysilyl) propyl methyl phosphate on the anode surface not only increases the hydrophilicity and active sites of the electrode surface, promotes the mass transfer and adsorption of pollutants to the electrode surface, but more importantly, the functional layer can effectively inhibit the formation of anode passivation layer, reduce electrode fouling, and ensure the stability of current efficiency and long-term durability of the electrode. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments 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.

[0024] 3-(trihydroxysilyl) propyl methyl phosphate (CAS number: 84962-98-1, purity 99%) is purchased from Hubei Xinhongli Chemical Co., Ltd.

[0025] Cationic polyacrylamide (CAS number: 25085-02-3, purity 99%) is purchased from Hubei Junrui Biological Technology Co., Ltd.

[0026] Embodiment 1: A wastewater treatment method based on the electric flocculation technology for efficient phosphorus and heavy metal removal, comprising the following steps:

[0027] S1.1, introducing the wastewater to be treated into an electric flocculation reaction tank, and adjusting the pH to 6.0 with 0.1 mol / L sodium hydroxide;

[0028] S1.2, a composite multi-metal composed of iron, magnesium, aluminum and zirconium alloy, wherein the mass percentage of each metal is: iron 40%, aluminum 30%, magnesium 20% and zirconium 10%;

[0029] The functional anode plate prepared by the composite multi-metal and the inert cathode plate (titanium plate) form an electrode group, which performs electric flocculation reaction under the action of a direct current field, and the current density is 10 mA / cm 2 , the electrolysis time is 15 min, and 10 mg / L of cationic polyacrylamide is added to the wastewater;

[0030] S1.3, settling the wastewater after electric flocculation, separating and removing the flocculation body, and obtaining purified water.

[0031] The preparation process of the functional anode plate is as follows:

[0032] The anode substrate is cleaned by ultrasonic cleaning in acetone for 5 min to remove oil, then rinsed with ethanol and air dried; the surface is activated by 0.5% dilute nitric acid for 1 min, then rinsed with deionized water and air dried to obtain a pretreated anode substrate;

[0033] 3-(trihydroxysilyl)propyl methyl phosphate is dissolved in deionized water (molar ratio 1:1), the pH is adjusted to 4 with 0.1 mol / L acetic acid, and stirred at 300 rpm for 20 min to obtain a hydrolysis solution;

[0034] The pretreated anode substrate is immersed in the hydrolysis solution and reacted at 40°C for 45 min, then dried at 80°C for 30 min to obtain a functional anode plate with a grafted layer thickness of 20 nm.

[0035] Example 2: Compared with Example 1, the difference is that the molar ratio of deionized water to 3-(trihydroxysilyl)propyl methyl phosphate is 1:2.

[0036] Example 3: Compared with Example 1, the difference is that the molar ratio of deionized water to 3-(trihydroxysilyl)propyl methyl phosphate is 1:3.

[0037] Example 4: Compared with Example 1, the difference is that the grafted layer thickness is 50 nm.

[0038] Example 5: Compared with Example 1, the difference is that the grafted layer thickness is 80 nm.

[0039] Determination of accelerated life: using an electrochemical workstation, a three-electrode system (using the prepared functional anode as the working electrode, platinum or graphite as the counter electrode, and saturated calomel electrode (SCE) as the reference electrode); in the simulated wastewater electrolyte solution (such as 0.1 mol / L sodium sulfate), linear sweep voltammetry (LSV) test is carried out, and scanning is carried out to the anode oxygen evolution potential region, by comparing the polarization curves of the modified anode before and after modification, the oxygen evolution overpotential (reflecting the catalytic activity) and the passivation region characteristics can be evaluated; constant current electrolysis is carried out at a higher current density (such as 100 mA / cm 2 ), and the change curve of the working electrode potential with time is recorded, the point of sharp rise of the potential is the passivation point, and the time experienced is the accelerated life of the electrode.

[0040] Grafting layer bonding strength measurement: the sample is placed in an ultrasonic cleaner with a certain power (e.g. 100 W) and treated in deionized water for a period of time (e.g. 10-30 minutes); after drying, the change in the atomic percentage content of the surface phosphorus (P) element is measured using electron spectroscopy (EDS).

[0041] Pollutant removal efficiency measurement: a small-scale electrocoagulation reactor is assembled using the functional anode plate to treat simulated wastewater containing phosphorus (e.g. potassium dihydrogen phosphate) and heavy metals (e.g. Cu 2+ ) with a known initial concentration (C0); after the reaction is completed under optimal process conditions (e.g. specific current density, electrolysis time), the supernatant is taken; the total phosphorus concentration (C1) in the effluent is determined by ammonium molybdate spectrophotometry; the residual concentration of heavy metals in the effluent is determined by atomic absorption spectrometry; the removal rate is calculated as [(C0-C1) / C0] x 100%.

[0042] Table 1 Performance data of functional anode plate

[0043] accelerated life bond strength phosphorus removal rate copper ion removal rate example 1 48h 85% 95.5% 96.8% example 2 62h 92% 98.2% 98.5% example 3 55h 88% 96.8% 97.5% example 4 105h 96% 99.5% 99.2% example 5 ＞150h 99% 98.0% 98.8%

[0044] Comparative Examples 1, 2, and 3, Example 2 (molar ratio 1:2) exhibits better overall performance, indicating that at this concentration, the silane hydrolysis is sufficient to form a dense and stable monolayer grafting layer on the substrate surface.

[0045] Example 1 (molar ratio 1:1) has insufficient silane concentration, resulting in incomplete coverage of the grafting layer and poor density, so its stability and bonding strength are relatively low; Example 3 (molar ratio 1:3) has too high a concentration, causing the silane molecules to self-polymerize in the solution and then physically adsorb onto the substrate. The bonding force of this multi-layer physically adsorbed layer is not as strong as that of the chemically bonded monolayer, so its durability and performance are somewhat inferior to those of Example 2.

[0046] Comparative Examples 1, 4, and 5, increasing the thickness of the grafting layer can greatly improve the stability and durability of the anode; as shown in the table, increasing from 20 nm to 50 nm and then to 80 nm, the accelerated life is extended from 48 hours to more than 150 hours, and the bonding strength (element retention rate) is also increased from 85% to 99%; this is because a thicker organic-inorganic hybrid layer can more effectively isolate the anode substrate from the electrolyte and inhibit the formation of a passivation film, and its physical barrier effect is also stronger.

[0047] However, the thickness increase has an optimal interval for the electrochemical activity and the pollutant removal efficiency; the removal rate of Example 4 (50 nm) is higher, indicating that this thickness provides excellent protection while not significantly hindering the dissolution of metal ions and the occurrence of electrochemical reactions; although Example 5 (80 nm) is the most durable, the excessively thick grafted layer hinders the charge transfer and the dissolution of metal ions to some extent, resulting in a slight decrease in activity and a slightly lower removal rate than Example 4.

[0048] Example 6: A high-efficiency wastewater treatment method for removing phosphorus and heavy metals based on the electrocoagulation technology, comprising the following steps:

[0049] S1.1, introducing the wastewater to be treated into an electrocoagulation reaction tank and adjusting the pH to 7.0 with 0.1 mol / L sodium hydroxide;

[0050] S1.2, the composite multi-metal is composed of iron, magnesium, aluminum and zirconium alloy, and the mass percentage of each metal is: iron 60%, aluminum 16%, magnesium 16% and zirconium 8%;

[0051] The functional anode plate prepared by the composite multi-metal and the inert cathode plate (graphite plate) form an electrode group, which performs electrocoagulation reaction under the action of a direct current field, and the current density is 20 mA / cm 2 , the electrolysis time is 25 min, and 50 mg / L of cationic polyacrylamide is added to the wastewater;

[0052] S1.3, the wastewater after electrocoagulation reaction is settled, and the flocculation body is separated and removed to obtain purified water.

[0053] The preparation process of the functional anode plate is as follows:

[0054] The anode substrate is cleaned with acetone for 8 min to remove oil, then rinsed with ethanol and air dried; the surface is activated by 1.5% dilute nitric acid for 2 min, then rinsed with deionized water and air dried to obtain a pretreated anode substrate;

[0055] 3-(trihydroxysilyl)propyl methyl phosphate is dissolved in deionized water (molar ratio 1:2), the pH is adjusted to 4.5 with 0.1 mol / L acetic acid, and stirred at 350 rpm for 25 min to obtain a hydrolysis solution;

[0056] The pretreated anode substrate is immersed in the hydrolysis solution and reacted at 40°C for 80 min, then dried at 100°C for 60 min to obtain a functional anode plate with a grafted layer thickness of 50 nm.

[0057] Example 7: Compared with Example 6, the difference is that the pH is adjusted to 7.0 with 0.1 mol / L sodium hydroxide.

[0058] Example 8: The difference between this example and Example 6 is that the pH is adjusted to 7.5 with 0.1 mol / L sodium hydroxide.

[0059] Example 9: A high-efficiency phosphorus and heavy metal removal method for wastewater treatment based on electrocoagulation technology, comprising the following steps:

[0060] S1.1, the wastewater to be treated is introduced into an electrocoagulation reaction tank, and the pH is adjusted to 7.5 with 0.1 mol / L sodium hydroxide;

[0061] S1.2, a composite multi-metal composed of iron, magnesium, aluminum and zirconium alloy, wherein the mass percentage of each metal is: iron 70%, aluminum 10%, magnesium 15% and zirconium 5%;

[0062] The functional anode plate prepared by the composite multi-metal and the inert cathode plate (graphite plate) form an electrode group, which performs electrocoagulation reaction under the action of a direct current electric field, and the current density is 30 mA / cm 2 , the electrolysis time is 30 min, and 100 mg / L of cationic polyacrylamide is added to the wastewater;

[0063] S1.3, the wastewater after electrocoagulation reaction is settled, and the flocculation body is separated and removed to obtain purified water.

[0064] The preparation process of the functional anode plate is as follows:

[0065] The anode substrate is cleaned with acetone for 10 min to remove oil, then rinsed with ethanol and air dried; the surface is activated with 2% dilute nitric acid for 3 min, then rinsed with deionized water and air dried to obtain a pretreated anode substrate;

[0066] 3-(trihydroxysilyl)propyl methyl phosphate is dissolved in deionized water (molar ratio 1:2), the pH is adjusted to 5 with 0.1 mol / L acetic acid, and stirred at 400 rpm for 30 min to obtain a hydrolysis solution;

[0067] The pretreated anode substrate is immersed in the hydrolysis solution and reacted at 40℃ for 120 min, then dried at 120℃ for 90 min to obtain a functional anode plate with a grafted layer thickness of 50 nm.

[0068] Determination of pollutant removal efficiency: Collect representative water samples at the influent of the treatment system and the effluent after sedimentation, respectively; use ammonium molybdate spectrophotometry to determine the absorbance at a wavelength of 700 nm, and calculate the total phosphorus concentration by a standard curve; use inductively coupled plasma emission spectrometry to determine the heavy metal concentration; after pretreatment by appropriate acidification, the water sample is directly tested on the machine, and the concentration of various heavy metal elements is accurately quantified by comparing the spectral intensity at the characteristic wavelength with the standard curve; the removal rate is calculated as [(influent concentration - effluent concentration) / influent concentration] x 100%.

[0069] Determination of energy consumption: connect an electric energy meter or a power meter before the direct current power supply, and accurately record the total electrolysis time (t, hours) and the average operating voltage (U, volts) and average current (I, amperes) of the electric flocculation reaction stage (S1.2); calculate the energy consumption E (kWh / m 3 )=(U x I x t) / V, where V is the volume of the treated wastewater (cubic meters).

[0070] Determination of sludge production: collect all the flocculation bodies (sludge) separated in the sedimentation stage (S1.3); determination of wet sludge quantity: place the sludge in a Buchner funnel, and under a certain vacuum degree, filter for a certain time (such as 10 minutes) until no water drops, and weigh the obtained mud cake; determination of dry sludge quantity: take a certain volume of sludge or weighed wet mud cake, and place it in an oven at 105 ± 5°C to dry to a constant weight, and after cooling, weigh the dry weight.

[0071] Table 2 Performance data of treated wastewater

[0072] energy consumption wet sludge production dry sludge production total phosphorus removal rate copper ion removal rate example 6 4.8 kWh / m 3 ]] 1.8 kg / m 3 ]] 0.35 kg / m 3 ]] 88.5% 90.2% example 7 3.5 kWh / m 3 ]]> 2.2 kg / m 3 ]]> 0.52 kg / m 3 ]] 99.2% 99.5% example 8 4.0 kWh / m 3 ]]> 2.8 kg / m 3 ]]> 0.48 kg / m 3 ]] 96.0% 97.8%

[0073] Example 7 (pH = 7.0) showed high removal rates of phosphorus and copper ions (both > 99%); this indicates that under neutral conditions, the Fe 2+ / Al 3+ and other metal ions dissolved from the composite anode can rapidly hydrolyze to generate hydroxyl polymers with optimal flocculation effect; these positively charged colloids can most effectively remove negatively charged phosphate ions and heavy metal ions through electric neutralization, adsorption, and entrapment.

[0074] Example 6 (pH = 6.0) had a lower removal rate; under acidic conditions, the high concentration of H + suppressed the hydrolysis of metal ions, making it difficult to generate sufficient hydroxyl complexes with flocculation activity; at the same time, part of the phosphate existed in the form of H2PO4 - , which weakened the binding ability with the flocculant, resulting in a significant decrease in removal efficiency.

[0075] Example 8 (pH = 7.5) has a slightly lower removal rate. In weak alkaline conditions, more negatively charged hydroxyl complexes (such as Al(OH)4 - ) are generated from dissolved metal ions, which repel pollutants (such as PO4 3- ) through electrostatic repulsion, reducing the probability of collision and combination; at the same time, some heavy metals (such as Cu 2+ ) generate soluble ammine complexes or hydroxides, resulting in a failure to reach the peak removal rate.

[0076] Example 7 (pH = 7.0) has the lowest energy consumption. The optimal pH condition makes the electrochemical dissolution and flocculation reaction most efficient, with the highest current utilization rate, so the energy consumption per unit volume of wastewater treatment is the lowest.

[0077] Example 6 (pH = 6.0) has higher energy consumption. In acidic conditions, part of the electrical energy is used for hydrogen evolution reaction, and the solution resistance increases, resulting in a higher cell voltage required to maintain the same current density, thereby significantly increasing the energy consumption.

[0078] From Example 6 to Example 8, the amount of wet sludge gradually increases, because the higher the pH, the more complete the metal hydrolysis, and the larger the total volume of the generated flocculation body; the flocculation body of Example 8 is more loose and has a higher water content, resulting in the largest wet weight.

[0079] Example 7 has a larger amount of dry sludge, which indicates that at neutral pH, not only is the flocculation reaction most complete, but also the generated flocculation body has a dense structure and a high solid content, containing the largest amount of pollutant precipitation (metal phosphate, metal hydroxide); Example 6 has the least amount of dry sludge due to incomplete reaction; the dry sludge amount of Example 8 is slightly lower than that of Example 7, which is related to the formation of soluble complexes with some metals and not entering the sludge phase.

[0080] Through the above determination, Example 7 is taken as the optimal example;

[0081] Comparative Example 1: Compared with Example 7, the difference is that 3-(trihydroxysilyl) propyl methyl phosphate is not added in the preparation process of the functional anode plate.

[0082] Comparative Example 2: Compared with Example 7, the difference is that the anode substrate is not prepared by using a composite multi-metal, but a pure iron plate is directly used as the anode substrate.

[0083] Comparative Example 3: Compared with Example 7, the difference is that cationic polyacrylamide is not added.

[0084] Determination of water turbidity: take a certain volume of the settled effluent sample and use a turbidimeter to detect; use formaldehyde standard solution (0, 10, 20, 100 NTU) to calibrate the turbidimeter; inject the water sample into a colorimetric flask and place it into the turbidimeter for measurement, and the reading is the turbidity of the water sample (unit: NTU).

[0085] Table 3 Performance data of treated sewage

[0086] energy consumption wet sludge production total phosphorus removal rate copper ion removal rate water quality turbidity example 7 3.5 kWh / m 3 ]] 2.2 kg / m 3 ]]> 99.2% 99.5% 8 NTU comparative example 1 5.8 kWh / m 3 ]] 2.1 kg / m 3 ]] 95.8% 97.0% 12 NTU comparative example 2 4.5 kWh / m 3 ]] 3.5 kg / m 3 ]]> 86.5% 92.3% 15 NTU comparative example 3 3.6 kWh / m 3 ]]> slow settling 98.5% 99.0% 45 NTU

[0087] The energy consumption of Comparative Example 1 (without surface modification) increased significantly; the anode plate without silane modification was more prone to passivation during operation, and an oxide film was rapidly formed on the surface, resulting in an increase in resistance, so that the system had to provide a higher voltage to maintain the same current density, thereby causing a sharp rise in energy consumption.

[0088] The main role of the modified layer is to resist passivation rather than directly enhance activity, so at the beginning, the unmodified anode can still effectively dissolve metal ions, so the removal rate does not decrease significantly.

[0089] The treatment effect of Comparative Example 2 (pure iron anode) decreased overall; the flocculant generated by the pure iron anode is single (mainly iron hydrolysis products), and lacks the synergistic effect of metals such as aluminum and zirconium, especially the specific binding ability for phosphorus is weak, resulting in a significant decrease in total phosphorus removal rate; for some heavy metals, the removal effect is also inferior to the composite anode.

[0090] The relative atomic mass of iron is large, and the Fe(OH)3 flocculation is usually loose, with a high water content, resulting in a much higher amount of wet sludge than the composite anode (+59%) when treating the same pollutants, increasing the cost of subsequent sludge disposal.

[0091] The iron anode is also prone to passivation, and its electrochemical properties result in a slightly lower current efficiency than the optimized composite anode, so the energy consumption is higher than that of Example 7.

[0092] Comparative Example 3 (without cationic polyacrylamide) has a very poor solid-liquid separation effect; although the electrocoagulation reaction itself proceeds very thoroughly (the removal rate data is still high), the lack of bridging and capturing effect of cationic polyacrylamide results in small, loose, and extremely slow settling speed of the flocculation; within the set settling time, the water sample is still turbid, and a large amount of small flocculation cannot be settled, and in fact, it is impossible to obtain qualified purified water.

[0093] The addition of cationic polyacrylamide occurs after the electrochemical reaction, and only affects the physical settling process, so it has almost no effect on the power consumption.

[0094] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for high efficient removal of phosphorus and heavy metals from wastewater based on electrocoagulation technology, characterized in that, The method comprises the following steps: S1.1, introducing the sewage to be treated into an electrocoagulation reaction tank and adjusting pH; S1.2, using a functional anode plate prepared from a composite multi-metal composed of iron, magnesium, aluminum and zirconium alloy and an inert cathode plate to form an electrode group, and performing electrocoagulation reaction under the action of a direct current electric field; The mass percentage of each metal in the composite multi-metal is: iron 40-70%, aluminum 10-30%, magnesium 15-20%, and zirconium 5-10%; The inert cathode plate is a titanium plate or a graphite plate; The preparation process of the functional anode plate is as follows: The anode substrate is cleaned by ultrasonic washing with acetone for 5-10 min to remove oil, then rinsed with ethanol and dried; the surface is activated by treating with dilute nitric acid with a mass concentration of 0.5-2% for 1-3 min, then rinsed with deionized water and dried, to obtain a pretreated anode substrate; 3-(trihydroxysilyl) propyl methyl phosphate is dissolved in deionized water, wherein the molar ratio of deionized water to 3-(trihydroxysilyl) propyl methyl phosphate is 1:1-3, 0.1 mol / L acetic acid is used to adjust the pH to 4-5, and stirring is performed at a speed of 300-400 rpm for 20-30 min to obtain a hydrolysis solution; The pretreated anode substrate is immersed in the hydrolysis solution and reacted at 40°C for 45-120 min, then taken out and dried at 80-120°C for 30-90 min to obtain a functional anode plate with a grafted layer thickness of 20-80 nm; S1.3, performing sedimentation on the sewage after electrocoagulation reaction, separating and removing the flocculation body, and obtaining purified water.

2. The method for efficient removal of phosphorus and heavy metals from wastewater based on electrocoagulation technology according to claim 1, characterized in that, In the S1.1, the pH of the sewage to be treated is adjusted to 6.0-7.5 by using 0.1 mol / L sodium hydroxide.

3. The method for efficient removal of phosphorus and heavy metals from wastewater based on electrocoagulation technology according to claim 1, characterized in that, In the S1.2, the electric flocculation reaction current density is 10-30 mA / cm 2 , and the electrolysis time is 15-30 min.

4. The method for efficient removal of phosphorus and heavy metals from wastewater based on electrocoagulation technology as claimed in claim 1, wherein, In the S1.2, 10-100 mg / L of cationic polyacrylamide is added to the sewage during the electrocoagulation process.