A method for simultaneously removing organic matter and heavy metals from wastewater

Abstract

The present application belongs to the technical field of wastewater treatment, and provides a method for simultaneously removing organic matter and heavy metals in wastewater. The method comprises: sequentially adding an iron-based homogeneous activator, a ligand regulator and an oxidizing agent into the wastewater to obtain a reaction system; allowing the reaction system to react to obtain a reaction liquid; sequentially adding the ligand regulator and a sodium hydroxide solution into the reaction liquid, allowing the reaction to proceed, and then performing magnetic separation to obtain a mixed liquid; adding a persulfate into the mixed liquid and allowing the mixture to stir to react; and limiting the composition of the ligand regulator. The method can simultaneously remove organic matter and heavy metals in composite-polluted wastewater. The iron-based homogeneous activator can activate the oxidizing agent to generate strong-oxidizing free radicals to degrade the organic matter. The ligand regulator has reduction and complexation effects at the same time, effectively improves the efficiency of oxidizing removal of the organic matter, and reacts with the sodium hydroxide solution to generate functional magnetic substances, which have good adsorption effect on the heavy metals.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for simultaneously removing organic matter and heavy metals from wastewater. Background Technology

[0002] The coexistence of organic matter (such as dyes, pesticides, antibiotics, etc.) and heavy metals (such as lead, cadmium, mercury, arsenic, etc.) not only exacerbates the difficulty of wastewater treatment, but also intensifies ecological risks and harms to human health.

[0003] Currently, wastewater treatment technologies for single pollutants are relatively mature. For organic pollutants, technologies include activated carbon adsorption, advanced oxidation technologies, and biodegradation technologies. However, these methods are not effective at removing heavy metals and may even reduce their treatment efficiency due to competitive adsorption or redox reactions. For heavy metal pollutants, technologies include chemical precipitation, ion exchange, and adsorption. However, these methods are also ineffective at degrading organic matter and may even clog adsorption sites or deactivate the precipitant due to organic matter, thus reducing their treatment efficiency for heavy metals.

[0004] Existing research has explored the simultaneous removal of organic matter and heavy metals through combined treatment processes or the development of multifunctional materials. For example, patent CN120381870A discloses the application of an in-situ nano-manganese dioxide@zeolite composite material in removing metal ions and micro-pollutants from water. This method removes micro-pollutants by activating oxidants such as persulfate, while simultaneously adsorbing and removing heavy metal ions. However, this method is only suitable for removing trace amounts of organic pollutants from drinking water sources, and it can only remove small-molecule organic pollutants, making it unsuitable for industrial wastewater with complex compositions and high pollutant concentrations. Patent CN120288751A discloses the preparation of biochar using plant tissue from black nightshade plants after the combined remediation of cadmium-contaminated soil with fungi and black nightshade. This biochar is then added to water bodies contaminated with cadmium and tetracycline, and the pollutants are removed by centrifugal filtration. However, this method suffers from high energy consumption and cost in biochar preparation, the biochar after adsorbing organic pollutants is prone to deactivation and difficult to regenerate, and organic pollutants and heavy metals compete for adsorption sites, resulting in limited treatment efficiency. It is evident that current methods for treating wastewater contaminated with a mixture of organic matter and heavy metals suffer from problems such as low treatment efficiency, poor material stability, and high energy consumption.

[0005] Therefore, there is an urgent need to develop efficient, stable, and environmentally friendly wastewater treatment methods that can simultaneously remove organic matter and heavy metals, avoid secondary pollution, and achieve resource recovery. Summary of the Invention

[0006] The purpose of this invention is to provide a method for simultaneously removing organic matter and heavy metals from wastewater, addressing the shortcomings of existing technologies.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for simultaneously removing organic matter and heavy metals from wastewater, comprising the following steps:

[0009] 1) Add an iron-based homogeneous activator, a ligand modifier, and an oxidant sequentially to the wastewater to obtain a reaction system; the reaction system undergoes a reaction to obtain a reaction solution;

[0010] 2) Add the ligand regulator and sodium hydroxide solution dropwise to the reaction solution in sequence, carry out the reaction, and then separate magnetically to obtain a mixture;

[0011] 3) Add persulfate to the mixture and stir to react;

[0012] The ligand regulator is a mixture of cysteine ​​and citric acid;

[0013] The molar ratio of cysteine ​​to citric acid is independently 1 to 10:1.

[0014] Preferably, the iron-based homogeneous activator in step 1) is an iron salt and / or a ferrous salt, and the oxidant is one or more of hydrogen peroxide, persulfate, calcium peroxide, calcium percarbonate and peracetic acid.

[0015] Preferably, in the reaction system described in step 1), the total iron concentration is 150–500 mmol / L, the ligand regulator concentration is 5–100 mmol / L, and the oxidant concentration is 5–350 mmol / L.

[0016] Preferably, the reaction time in step 1) is 15–300 min;

[0017] During the reaction described in step 1), stirring is performed at a speed of 50 to 550 rpm.

[0018] Preferably, the amount of ligand regulator added in step 2) is 150–500 mmol / L.

[0019] Preferably, the concentration of the sodium hydroxide solution in step 2) is 0.5–5 mol / L, and the amount of sodium hydroxide solution added is sufficient to make the pH value of the reaction solution > 11.

[0020] Preferably, the dropping rate in step 2) is 1–10 mL / min;

[0021] In step 2), the reaction solution is subjected to ultrasonication and stirring simultaneously with the dropwise addition.

[0022] The reaction in step 2) is carried out under ultrasound and stirring, and the reaction time in step 2) is 10 to 180 min.

[0023] Preferably, the acoustic energy density of the ultrasound is 0.5–10 W / cm². 3 The stirring speed is 50 to 250 rpm.

[0024] Preferably, the persulfate independently includes one or more of sodium persulfate, sodium persulfate, potassium persulfate, potassium persulfate, ammonium persulfate, ammonium persulfate, calcium persulfate, and calcium persulfate;

[0025] The amount of persulfate added in step 3) is 10-50 mmol / L.

[0026] Preferably, the stirring speed in step 3) is 50-550 rpm, and the stirring time is 6-96 h.

[0027] The beneficial effects of this invention are:

[0028] 1) The method of the present invention can simultaneously remove organic matter and heavy metals from complex polluted wastewater, reduce sludge production during water treatment, and the magnetic products after magnetic separation still have adsorption sites and have the potential to adsorb pollutants.

[0029] 2) Iron-based homogeneous activators can activate oxidants to generate highly oxidizing free radicals, thus degrading organic matter; ligand regulators have both reducing and complexing effects, which can promote the reaction of Fe in the system. 3+ / Fe 2+ Cycle, simultaneously with Fe 3+ Fe 2+ Forming a complex, which acts as a barrier to Fe 3+ Fe 2+ The sustained-release effect effectively improves the efficiency of oxidative removal of organic matter; the ligand regulator will release some of the Fe in the reaction solution. 3+ Reduced to Fe 2+ and with Fe 3+ Fe 2+ The formation of complexes; the addition of sodium hydroxide solution creates an alkaline environment, and under the action of ultrasound, the complexed Fe... 3+ and Fe 2+ With OH - The reaction generates a functionalized magnetic material with Fe3O4 as the main component and modified by a ligand regulator, which has a good adsorption effect on heavy metals. The residual oxidant undergoes thermal decomposition under the high temperature and high pressure generated by the cavitation effect of ultrasound, producing strong oxidizing free radicals, which further remove organic matter. The mixture obtained in step 3) is alkaline. Persulfate is added to the mixture. Under alkaline activation, the persulfate produces strong oxidizing free radicals, which further remove organic matter in the wastewater, and at the same time neutralize the alkalinity of the mixture to a certain extent.

[0030] 3) The selection of ligand regulators in this invention plays a crucial role in the removal of organic matter and heavy metals. By using a ligand regulator composed of cysteine ​​and citric acid, the simultaneous and effective removal of organic pollutants and heavy metals from wastewater is achieved under the condition of reasonably controlling the ratio of cysteine ​​and citric acid. Attached Figure Description

[0031] Figure 1 The image shows the magnetic functionalized material obtained in step 2 of Example 2;

[0032] Figure 2 This is an image of the magnetic functionalized material obtained in step 2 of Example 3. Detailed Implementation

[0033] This invention provides a method for simultaneously removing organic matter and heavy metals from wastewater, comprising the following steps:

[0034] 1) Add an iron-based homogeneous activator, a ligand modifier, and an oxidant sequentially to the wastewater to obtain a reaction system; the reaction system undergoes a reaction to obtain a reaction solution;

[0035] 2) Add the ligand regulator and sodium hydroxide solution dropwise to the reaction solution in sequence, carry out the reaction, and then separate magnetically to obtain a mixture;

[0036] 3) Add persulfate to the mixture and stir to react;

[0037] The ligand regulator is a mixture of cysteine ​​and citric acid;

[0038] The molar ratio of cysteine ​​to citric acid is independently 1 to 10:1.

[0039] In this invention, the molar ratio of cysteine ​​to citric acid is preferably 3 to 8:1, more preferably 5 to 7:1, and even more preferably 6:1.

[0040] In this invention, the iron-based homogeneous activator in step 1) is preferably an iron salt and / or a ferrous salt, and the oxidant is preferably one or more of hydrogen peroxide, persulfate, calcium peroxide, calcium percarbonate and peracetic acid.

[0041] In this invention, the iron salt is preferably a soluble iron salt, and the soluble iron salt preferably includes one or more of ferric sulfate, ferric nitrate and ferric chloride;

[0042] The ferrous salt is preferably a soluble ferrous salt, which preferably includes one or more of ferrous sulfate, ferrous nitrate and ferrous chloride.

[0043] In this invention, the iron-based homogeneous activator is preferably added in solution form, and the oxidant is preferably added in solution form.

[0044] In this invention, in the reaction system described in step 1), the total iron concentration is preferably 150–500 mmol / L, more preferably 200–400 mmol / L, and even more preferably 250–300 mmol / L; the concentration of the ligand regulator is preferably 5–100 mmol / L, more preferably 10–75 mmol / L, and even more preferably 30–50 mmol / L; and the concentration of the oxidant is preferably 5–350 mmol / L, more preferably 50–300 mmol / L, and even more preferably 100–200 mmol / L.

[0045] In this invention, the pH value of the solution needs to be controlled to 2-11 before adding the oxidant in step 1), and more preferably to 5-9;

[0046] The preferred reagents for adjusting pH value are sodium hydroxide solution or sulfuric acid.

[0047] In this invention, the reaction time in step 1) is preferably 15-300 min, more preferably 50-250 min, and even more preferably 100-180 min;

[0048] Stirring is preferably performed during the reaction process described in step 1), and the stirring speed is preferably 50-550 rpm, more preferably 150-450 rpm, and even more preferably 200-300 rpm.

[0049] In this invention, the amount of ligand regulator added in step 2) is preferably 150-500 mmol / L, more preferably 200-400 mmol / L, and even more preferably 250-300 mmol / L.

[0050] In this invention, the amount of ligand regulator added in step 2) is preferably the same as the total iron concentration in the reaction system in step 1).

[0051] In this invention, the concentration of the sodium hydroxide solution in step 2) is preferably 0.5-5 mol / L, more preferably 1-4 mol / L, and even more preferably 2-3 mol / L. The amount of sodium hydroxide solution added is preferably sufficient to make the pH value of the reaction solution > 11.

[0052] In this invention, the dripping rate in step 2) is preferably 1-10 mL / min, more preferably 3-8 mL / min, and even more preferably 5 mL / min;

[0053] In step 2), the reaction solution is preferably subjected to ultrasonication and stirring during the dropwise addition.

[0054] The reaction in step 2) is preferably carried out under ultrasound and stirring. The reaction time in step 2) is preferably 10 to 180 min, more preferably 60 to 120 min, and even more preferably 80 to 100 min.

[0055] In this invention, the acoustic energy density of the ultrasonic wave is preferably 0.5–10 W / cm². 3 Further preferred is 3-8 W / cm 3 More preferably 5-6 W / cm 3 The stirring speed is preferably 50-250 rpm, more preferably 100-200 rpm, and even more preferably 150 rpm.

[0056] In this invention, the persulfate preferably includes one or more of sodium persulfate, sodium persulfate, potassium persulfate, potassium persulfate, ammonium persulfate, ammonium persulfate, calcium persulfate, and calcium persulfate.

[0057] The amount of persulfate added in step 3) is preferably 10-50 mmol / L, more preferably 20-40 mmol / L, and even more preferably 30 mmol / L.

[0058] In this invention, the stirring speed in step 3) is preferably 50-550 rpm, more preferably 150-450 rpm, and even more preferably 200-300 rpm; the stirring time is preferably 6-96 h, more preferably 24-72 h, and even more preferably 36-48 h.

[0059] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0060] The wastewater to be treated in the embodiments and comparative examples of this invention is coking wastewater generated by the Ningdong Energy and Chemical Base.

[0061] Example 1

[0062] (1) At room temperature and pressure, a ferrous sulfate solution (concentration of 500 mmol / L), a mixture of cysteine ​​and citric acid (molar ratio of cysteine ​​to citric acid of 3:1) was added to coking wastewater. At this time, the pH of the mixture was 5. Then, a sodium persulfate stock solution (PS stock solution) with a concentration of 250 mmol / L was added at 300 rpm to obtain the reaction system. The concentration of ferrous ions in the reaction system was 150 mmol / L, the total concentration of cysteine ​​and citric acid was 75 mmol / L, and the concentration of PS was 50 mmol / L. The reaction system was reacted at 300 rpm for 180 min to obtain the reaction solution. The concentration of volatile phenols in the reaction solution was determined according to HJ 503-2009 "Determination of Volatile Phenols in Water - 4-Aminoantipyrine Spectrophotometric Method", and the COD of the reaction solution was determined according to HJ828-2017 "Determination of Chemical Oxygen Demand in Water - Dichromate Method". The removal rate of volatile phenols in step (1) was 52.39%, and the removal rate of COD was 39.07%.

[0063] (2) Place the reaction solution into a container with a sound energy density of 3 W / cm². 3 The mixture was stirred in an ultrasonic generator at 150 rpm while a mixture of cysteine ​​and citric acid (molar ratio of cysteine ​​to citric acid 1:1) was added dropwise at a rate of 5 mL / min until the total concentration of cysteine ​​and citric acid reached 150 mmol / L. Then, a 1 mol / L sodium hydroxide solution was added dropwise at a rate of 5 mL / min until the pH of the reaction solution reached 11.5. The addition was then stopped. The reaction was continued at a rate of 3 W / cm². 3 The reaction was carried out at a sound energy density of 150 rpm for 60 minutes. After the reaction, the Fenton iron mud was converted into a black precipitate, and the magnetic material was separated by a magnet to obtain a mixed solution with a pH of 11.1. The volatile phenol concentration of the mixed solution was determined according to HJ 503-2009 "Determination of Volatile Phenols in Water - 4-Aminoantipyrine Spectrophotometric Method", the COD of the mixed solution was determined according to HJ 828-2017 "Determination of Chemical Oxygen Demand in Water - Dichromate Method", and the heavy metal content was determined according to HJ 776-2015 "Determination of 32 Elements in Water - Inductively Coupled Plasma Atomic Emission Spectrometry". The volatile phenol removal rate in step (2) was 18.52%, the COD removal rate was 20.03%, and the heavy metal removal results are shown in Table 1.

[0064] (3) Add a 250 mmol / L sodium persulfate solution (PS solution) to the mixture until the PS concentration in the mixture is 50 mmol / L. Then stir the mixture at 300 rpm for 24 hours to obtain the treated wastewater. The volatile phenol concentration of the treated wastewater was determined according to HJ 503-2009 "Determination of Volatile Phenols in Water - 4-Aminoantipyrine Spectrophotometric Method", and the COD of the treated wastewater was determined according to HJ 828-2017 "Determination of Chemical Oxygen Demand in Water - Dichromate Method". The volatile phenol removal rate in step (3) was 4.96%, and the COD removal rate was 29.26%.

[0065] Table 1 shows the heavy metal removal status in step (2) of Example 1.

[0066]

[0067] The total volatile phenol removal rate in this embodiment was 75.87%, and the total COD removal rate was 88.36%, indicating that the method of the present invention has excellent removal effect on organic matter in wastewater; the concentration of heavy metals in the treated wastewater was below the emission standard limit, indicating that the method of the present invention has excellent removal effect on heavy metals in wastewater.

[0068] Example 2

[0069] (1) At room temperature and pressure, a ferrous sulfate solution (500 mmol / L), a mixture of cysteine ​​and citric acid (molar ratio of cysteine ​​to citric acid 1:1) was added to coking wastewater. At this point, the pH of the mixture was 6.5. Then, a 250 mmol / L sodium persulfate stock solution (PS stock solution) was added at 300 rpm to obtain the reaction system. The concentration of ferrous ions in the reaction system was 300 mmol / L, the total concentration of cysteine ​​and citric acid was 100 mmol / L, and the concentration of PS was 75 mmol / L. The reaction system was reacted at 300 rpm for 180 min to obtain the reaction solution. The concentration of volatile phenols and COD in the reaction solution were determined in the same manner as in Example 1.

[0070] (2) Place the reaction solution into a container with a sound energy density of 3 W / cm². 3 The mixture was stirred in an ultrasonic generator at 150 rpm while a mixture of cysteine ​​and citric acid (molar ratio of cysteine ​​to citric acid 5:1) was added dropwise at a rate of 10 mL / min until the total concentration of cysteine ​​and citric acid reached 300 mmol / L. Then, a 1 mol / L sodium hydroxide solution was added dropwise at a rate of 5 mL / min until the pH of the reaction solution reached 11. The addition was then stopped. 3The reaction was carried out at a sound energy density of 150 rpm for 60 minutes. After the reaction, the Fenton iron sludge was converted into a black precipitate, and the magnetic material was separated by a magnet to obtain a mixed solution with a pH of 10.7. The magnetic material was then vacuum dried at 30 MPa and -20℃ for 24 hours to obtain the magnetic functionalized material.

[0071] (3) Add a 250 mmol / L sodium persulfate solution (PS solution) to the mixture until the concentration of PS in the mixture is 10 mmol / L. Then stir the mixture at 150 rpm for 24 hours to obtain the treated wastewater.

[0072] In this embodiment, the total volatile phenol removal rate was 72.35%, the total COD removal rate was 81.29%, and the heavy metal removal was shown in Table 2.

[0073] Table 2. Heavy metal removal status in Example 2

[0074]

[0075] Example 3

[0076] Replace the ferrous sulfate solution in step 1 of Example 2 with ferric nitrate solution, and the rest is the same as in Example 2.

[0077] In this embodiment, the total volatile phenol removal rate was 70.67%, the total COD removal rate was 79.52%, and the heavy metal removal status is shown in Table 3.

[0078] Table 3. Heavy metal removal status in Example 3

[0079]

[0080]

[0081] Example 4

[0082] The molar ratio of cysteine ​​to citric acid in step 1 of Example 1 was modified to 7:1, and the rest was the same as in Example 1.

[0083] The total volatile phenol removal rate in this embodiment was 73.15%, the total COD removal rate was 84.72%, and the heavy metal removal was shown in Table 4.

[0084] Table 4. Heavy metal removal status in Example 4

[0085]

[0086] Example 5

[0087] The molar ratio of cysteine ​​to citric acid in step 2 of Example 1 was modified to 5:1, and the rest was the same as in Example 1.

[0088] In this embodiment, the total volatile phenol removal rate was 73.16%, the total COD removal rate was 85.24%, and the heavy metal removal status is shown in Table 5.

[0089] Table 5. Heavy metal removal status in Example 5

[0090]

[0091] Example 6

[0092] (1) At room temperature and pressure, a ferrous sulfate solution (concentration of 300 mmol / L), a mixture of cysteine ​​and citric acid (molar ratio of cysteine ​​to citric acid of 7:1) was added to coking wastewater. The pH of the coking wastewater was adjusted to 9 using a 1 mol / L NaOH solution. Then, a 250 mmol / L sodium persulfate stock solution (PS stock solution) was added at 500 rpm to obtain the reaction system. The concentration of ferrous ions in the reaction system was 500 mmol / L, the total concentration of cysteine ​​and citric acid was 100 mmol / L, and the concentration of PS was 350 mmol / L. The reaction system was reacted at 500 rpm for 250 min to obtain the reaction solution.

[0093] (2) Place the reaction solution into a container with a sound energy density of 10 W / cm². 3 In an ultrasonic generator, a mixture of cysteine ​​and citric acid (molar ratio of cysteine ​​to citric acid 3:1) was added dropwise at a rate of 10 mL / min with stirring at 250 rpm until the total concentration of cysteine ​​and citric acid reached 500 mmol / L. Simultaneously, a 1 mol / L sodium hydroxide solution was added dropwise at a rate of 8 mL / min until the pH of the reaction solution reached 12. The addition was then stopped. 3 The reaction was carried out at a sound energy density of 250 rpm for 120 minutes. After the reaction, the Fenton iron mud was converted into a black precipitate, and the magnetic material was separated by a magnet to obtain a mixed solution with a pH of 11.8.

[0094] (3) Add a 250 mmol / L sodium persulfate solution (PS solution) to the mixture until the PS concentration in the mixture is 30 mmol / L. Then stir the mixture at 150 rpm for 72 h to obtain the treated wastewater. The concentration of volatile phenols and COD in the treated wastewater were determined in the same manner as in Example 1.

[0095] In this embodiment, the total volatile phenol removal rate was 71.28%, the total COD removal rate was 90.96%, and the heavy metal removal status is shown in Table 6.

[0096] Table 6. Heavy metal removal status in Example 6

[0097]

[0098] Comparative Example 1

[0099] Omit cysteine ​​and citric acid in step (1) of Example 2, and the rest is the same as in Example 2.

[0100] The total volatile phenol removal rate of this comparative example was 45.58%, the total COD removal rate was 57.75%, and the heavy metal removal results are shown in Table 7.

[0101] Table 7 shows the heavy metal removal status in Comparative Example 1.

[0102]

[0103] Comparative Example 2

[0104] Omit cysteine ​​and citric acid in step (1) of Example 3, otherwise remain the same as in Example 3.

[0105] The total volatile phenol removal rate of this comparative example was 42.78%, the total COD removal rate was 58.98%, and the heavy metal removal results are shown in Table 8.

[0106] Table 8. Heavy metal removal status in Comparative Example 2

[0107]

[0108] Comparative Example 3

[0109] The citric acid in step (1) and step (2) of Example 1 are omitted, and the rest is the same as in Example 1.

[0110] The total volatile phenol removal rate of this comparative example was 61.85%, the total COD removal rate was 72.54%, and the heavy metal removal results are shown in Table 9.

[0111] Table 9 shows the heavy metal removal status in Comparative Example 3.

[0112]

[0113] Comparative Example 4

[0114] The molar ratio of cysteine ​​to citric acid in step (1) of Example 1 was modified to 0.5:1, and the molar ratio of cysteine ​​to citric acid in step (2) was modified to 12:1. The rest was the same as in Example 1.

[0115] The total volatile phenol removal rate of this comparative example was 60.27%, the total COD removal rate was 72.41%, and the heavy metal removal results are shown in Table 10.

[0116] Table 10 shows the heavy metal removal status in Comparative Example 4.

[0117]

[0118] Figure 1 This is an image of the magnetic functionalized material obtained in step 2 of Example 2. Figure 2 This is an image of the magnetic functionalized material obtained in step 2 of Example 3.

[0119] As can be seen from the above embodiments, the present invention provides a method for simultaneously removing organic matter and heavy metals from wastewater. This method can simultaneously remove organic matter and heavy metals from mixed-polluted wastewater, reducing sludge production during water treatment. The magnetic products after magnetic separation still have adsorption sites and the potential to adsorb pollutants. The removal of organic matter mainly occurs in steps 1) and 3), while the removal of heavy metals mainly occurs in step 2). In step 1), a ligand regulator composed of cysteine ​​and citric acid is added, and by rationally controlling the ratio of cysteine ​​to citric acid, the Fe in the reaction system is promoted. 3+ / Fe 2+ The cycle improves the efficiency of oxidative removal of organic matter; step 2) adds a ligand regulator composed of cysteine ​​and citric acid, which promotes the generation of functionalized magnetic substances through reduction-complexation reaction, and plays a good role in adsorbing heavy metals.

[0120] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for simultaneously removing organic matter and heavy metals from wastewater, characterized by, It includes the following steps: 1) Add an iron-based homogeneous activator, a ligand modifier, and an oxidant sequentially to the wastewater to obtain a reaction system; the reaction system undergoes a reaction to obtain a reaction solution; 2) Add the ligand regulator and sodium hydroxide solution dropwise to the reaction solution in sequence, carry out the reaction, and then separate magnetically to obtain a mixture; 3) Add persulfate to the mixture and stir to react; The ligand regulator is a mixture of cysteine ​​and citric acid; The molar ratio of cysteine ​​to citric acid is independently 1 to 10:

1.

2. The method for simultaneously removing organic matter and heavy metals from wastewater according to claim 1, characterized in that, Step 1) The iron-based homogeneous activator is an iron salt and / or a ferrous salt, and the oxidant is one or more of hydrogen peroxide, persulfate, calcium peroxide, calcium percarbonate and peracetic acid.

3. The method for simultaneously removing organic matter and heavy metals from wastewater according to claim 1 or 2, characterized in that, In the reaction system described in step 1), the total concentration of iron is 150–500 mmol / L, the concentration of the ligand regulator is 5–100 mmol / L, and the concentration of the oxidant is 5–350 mmol / L.

4. The method for simultaneously removing organic matter and heavy metals from wastewater according to claim 3, characterized in that, The reaction time in step 1) is 15–300 min; During the reaction described in step 1), stirring is performed at a speed of 50 to 550 rpm.

5. The method for simultaneously removing organic matter and heavy metals from wastewater according to claim 4, characterized in that, The amount of ligand regulator added in step 2) is 150–500 mmol / L.

6. The method for simultaneously removing organic matter and heavy metals from wastewater according to claim 4 or 5, characterized in that, In step 2), the concentration of the sodium hydroxide solution is 0.5–5 mol / L, and the amount of sodium hydroxide solution added is sufficient to make the pH value of the reaction solution > 11.

7. The method for simultaneously removing organic matter and heavy metals from wastewater according to claim 6, characterized in that, The dropping rate in step 2) is 1–10 mL / min; In step 2), the reaction solution is subjected to ultrasonication and stirring simultaneously with the dropwise addition. The reaction in step 2) is carried out under ultrasound and stirring, and the reaction time in step 2) is 10 to 180 min.

8. The method for simultaneously removing organic matter and heavy metals from wastewater according to claim 7, characterized in that, The ultrasonic wave has a sound energy density of 0.5-10 W / cm 3 The stirring speed is 50-250 rpm.

9. The method for simultaneously removing organic matter and heavy metals from wastewater according to claim 2, characterized in that, The persulfate independently includes one or more of sodium persulfate, sodium persulfate, potassium persulfate, potassium persulfate, ammonium persulfate, ammonium persulfate, calcium persulfate, and calcium persulfate; The amount of persulfate added in step 3) is 10-50 mmol / L.

10. The method for simultaneously removing organic matter and heavy metals from wastewater according to claim 9, characterized in that, Step 3) The stirring speed is 50-550 rpm, and the stirring time is 6-96 h.

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