CN102381789A - Method for treating smelting wastewater containing heavy metals - Google Patents

Abstract

The invention discloses a treatment method for smelting wastewater containing heavy metals; the method pretreats the smelting wastewater containing heavy metals, removes particulate impurities in the wastewater and adjusts the pH value of the wastewater to be acidic, and then transfers the wastewater into an iron-carbon micro-electrolysis reactor Treatment, after single-stage or multi-stage micro-electrolysis electrochemical treatment under acidic conditions to remove most of the heavy metal ions in wastewater, adjust the pH value to be weakly alkaline or alkaline, and perform single-stage or multi-stage chemical flocculation treatment to further remove The remaining heavy metal ions and pollutants such as arsenic, fluorine, and chlorine in the wastewater are finally separated into solid and liquid to obtain recyclable production water. The whole treatment process consists of wastewater pretreatment, iron-carbon micro-electrolysis, chemical flocculation and solid-liquid separation in series. Coupling composition, the present invention combines micro-electrolysis and chemical flocculation organically, cooperates with each other to play a role together, has the advantages of simple treatment method and process, low treatment cost, high treatment efficiency, and the treated wastewater can be discharged up to standard and recycled.

Description

A kind of treatment method of smelting wastewater containing heavy metal

technical field

The invention relates to a treatment method for smelting wastewater containing heavy metals, which belongs to the field of environmental science and technology.

Background technique

Smelting wastewater containing heavy metals refers to industrial wastewater containing a large amount of heavy metals discharged during the production process of metallurgical industry. Smelting wastewater containing heavy metals (such as lead, cadmium, copper, mercury, zinc, arsenic, fluorine, etc.) is one of the most serious environmental pollution and one of the most harmful industrial wastewater to humans. Heavy metals in smelting wastewater containing heavy metals generally cannot be decomposed and destroyed, but can only transfer their location and change their physical and chemical forms. At present, in the actual treatment and application of heavy metal-containing smelting wastewater, methods such as neutralization precipitation method, ferrite method and vulcanization method are mainly used, but neutralization precipitation method and ferrite method have a large amount of slag and will produce secondary Pollution, high cost of vulcanization treatment. The electrochemical treatment technology has the advantages of high environmental compatibility, high energy utilization rate, controllability, multi-functionality and economy, and can better realize the purification of wastewater and the recovery of heavy metals. It has a great role in the treatment of heavy metal wastewater. It has a good application prospect, and with the continuous development of this treatment technology, it has become more widely a competitive heavy metal wastewater treatment method developed in recent years.

The invention mainly relates to the micro-electrolysis method in the treatment of heavy metal-containing wastewater, and the micro-electrolysis method has the characteristics of wide application range, simple process, good treatment effect, low energy consumption and the like. The principle of the micro-electrolysis method is very simple. It uses the potential difference between the iron-carbon particles to form countless tiny primary batteries, and uses wastewater as the electrolyte solution. It mainly uses electrochemical reactions and integrates redox, chemical replacement, etc. This role is used to treat smelting wastewater containing heavy metals. When immersing iron-carbon particles in wastewater, if the wastewater is highly acidic, the reduced iron will react with the acid to generate Fe ²⁺ . Under weak acid or neutral conditions, due to the electrode potential difference between iron and carbon, countless Micro primary battery.

When iron and carbon are submerged in wastewater, if the wastewater has a strong acidity, the reduced iron will react with the acid to generate Fe ²⁺ . Under weak acid or neutral conditions, due to the electrode potential difference between iron and carbon, the wastewater will Countless micro primary batteries will be formed. Among them, the iron with low potential becomes the anode, and the carbon with high potential becomes the cathode, and an electrochemical reaction occurs. The reaction process is as follows:

Anode (Fe): Fe-2e→Fe ²⁺ ;

Cathode (C): 2H ⁺ +2e→2[H]→H ₂ ,

Organic refractory pollutants + ne → easily degradable organic matter,

Heavy metal ion + ne → heavy metal element;

Iron can also displace less reactive heavy metal ions such as:

Fe+Cu ²⁺ →Cu+Fe ²⁺ ;

In the presence of oxygen and aeration in the water, the following reactions can also occur:

_O2 +4H ⁺⁺ 4e→ _2H2O ,

O ² +2H ₂ O+4e→4OH ^- ,

2Fe ²⁺ +O ₂ +4H ⁺ → 2H ₂ O+Fe ³⁺ .

It can be seen from the reaction that iron-carbon micro-electrolysis can precipitate heavy metals on the cathode carbon, but due to the chemical potential of heavy metal ions, it is difficult to achieve the discharge or return of heavy metal ions in wastewater after treatment with a single iron-carbon micro-electrolysis treatment. User requirements require further processing. In addition, the iron consumption of H ⁺ and the OH ^- produced by the micro-electrolysis reaction in the reaction are the reasons for the increase of the pH value of the effluent. However, if the Fe ²⁺ produced by iron-carbon micro-electrolysis can be oxidized to increase the pH value of the wastewater, the Fe ³⁺ can be gradually hydrolyzed to form Fe(OH) ₃ colloidal flocs with a high degree ^of polymerization, which can be obtained through Self-flocculation effectively adsorbs and condenses heavy metals, non-metallic pollution ions and other pollutants in water, thereby enhancing the purification effect of wastewater.

The comprehensive reactions such as redox, adsorption, flocculation, and replacement of micro-electrolysis can remove some metal ions and impurities in the water well, but the pH value only rises to 5-6 during the micro-electrolysis process, and Fe ²⁺ is only in the presence of The Fe ³⁺ oxidized under oxygen conditions does not undergo intensive treatment, and the amount of Fe(OH) ₃ colloidal flocs produced is small, and the adsorption and flocculation effects are weak. Therefore, micro-electrolysis is generally used as pretreatment, and subsequent treatment needs to be added later. After the iron-carbon micro-electrolysis, the method of chemical flocculation is used for further treatment. The purpose of aeration and adding oxidants in the process of iron-carbon micro-electrolysis and chemical flocculation is to improve the process of Fe ³⁺ generated by Fe ²⁺ oxidation, and also to change the waste water. The process of chemical states such as arsenic, chromium, cadmium, etc.; the purpose of increasing the pH value in water is to make colloidal flocs such as Fe(OH) ₃ formed by Fe ³⁺ self-flocculation, and the purpose of adding flocculants is to promote Fe(OH) ₃ The production of colloidal flocs and the increase of fine flocs, thereby further improving the flocculation of Fe(OH) ₃ colloidal flocs and the effect of adsorbing pollutants in water, so it can further reduce heavy metal and non-metal pollution in wastewater The content of ions, while the aeration of the process and the determination of adding oxidants need to be determined according to the nature of the wastewater.

For smelting wastewater containing heavy metals, the micro-electrolysis method has a good effect on the treatment of heavy metal ions, but has a poor effect on non-metallic pollution ions (such as arsenic, fluorine, etc.). Fluorine, etc.) has a good treatment effect, but the treatment effect on heavy metal ions with a higher concentration is not ideal. The present invention considers the combination of the micro-electrolysis method and the chemical flocculation method, organically integrates the functions of the two technologies, cooperates with each other to play a role, fully exerts the respective advantages of the two treatment methods, and satisfies the requirements of heavy metal-containing smelting wastewater. The characteristics and requirements of the treatment solve the problem that the use of micro-electrolysis and chemical flocculation alone cannot make the wastewater treatment meet the standard. At the same time, chemical flocculation is used to enhance the removal of pollutants in smelting wastewater containing heavy metals, so as to achieve efficient and low-cost treatment. The purpose of smelting wastewater containing heavy metals and recovering heavy metals in wastewater.

the

Contents of the invention

The purpose of the present invention is to provide a treatment method for smelting wastewater containing heavy metals, which is based on the principle of micro-electrolysis and chemical flocculation, and the two methods are organically coupled for the treatment of smelting wastewater containing heavy metals, especially suitable for complex heavy metals Treatment of smelting wastewater.

The present invention adopts the method of combining iron-carbon micro-electrolysis and chemical flocculation treatment to remove heavy metal ions and other pollutants in the heavy metal-containing smelting wastewater. The specific method is to pretreat the heavy-metal-containing smelting wastewater, remove particulate impurities in the wastewater, and adjust the pH value of the wastewater. 2.0-5.0, then transfer the pretreated wastewater into the iron-carbon micro-electrolysis reactor, perform single-stage or multi-stage micro-electrolysis electrochemical treatment under acidic conditions to remove most of the heavy metal ions in the wastewater, and then adjust the pH value , carry out single-stage or multi-stage chemical flocculation treatment, further remove the remaining heavy metal ions and other non-metallic pollution ions in the wastewater, such as arsenic, fluorine, chlorine and other pollutants, and finally perform solid-liquid separation to obtain recyclable production water. The treatment process consists of wastewater pretreatment, iron-carbon micro-electrolysis, chemical flocculation and solid-liquid separation in series. The method of the present invention can be used alone or as a unit process in the treatment of heavy metal-containing smelting wastewater combined with other methods to form a complete treatment Technology for smelting wastewater containing heavy metals.

The pretreatment of heavy metal-containing smelting wastewater in the present invention is based on the properties of heavy-metal-containing smelting wastewater and the requirements of the micro-electrolysis reaction. Before micro-electrolysis, the pH of the heavy-metal-containing smelting wastewater is adjusted to 2 to 5 with acid or alkali to change the properties of the wastewater. One or more of the pretreatment methods such as grille, screening, aeration and grit settling, sedimentation and separation, adding flocculant flocculation and sedimentation to remove particulate impurities in wastewater, to ensure that heavy metal-containing smelting wastewater meets the requirements and guarantees of micro-electrolysis treatment The iron-carbon micro-electrolysis reaction bed is not blocked by particulate impurities.

The pH acid-base regulator used in the present invention is: (1) the alkaline substance is various available industrial waste alkali, sodium hydroxide, sodium carbonate, limestone (powder) or milk of lime (powder); (2) the acidic substance is Various available industrial waste acids, waste acids to be treated and acid waste water, sulfuric acid, hydrochloric acid, nitric acid.

In the present invention, the iron-carbon micro-electrolysis reactor is an arbitrary combination of one or more of iron-carbon micro-electrolysis reaction-based fixed bed, rolling bed and fluidized bed, and the iron-carbon micro-electrolysis reaction is single-stage or multiple Level reaction, the residence time of each level of micro-electrolysis reaction is generally 5-120min.

In the present invention, the iron-carbon micro-electrolysis reaction bed is an iron-carbon mixed particle bed, an iron-carbon structured packing bed, or a mixed bed composed of iron-carbon mixed particles and structured packing; the sum of the total mass of iron particles and carbon particles in the iron-carbon mixed particle bed accounts for The total mass is more than 80%, and the ratio of iron to carbon mass is 1-10:1; the iron-carbon structured packing bed is a combination of iron particles and carbon particles with different shapes and micropores. This combination is Sintered (such as high-carbon sponge iron structured packing), or bonded, in which the total mass of iron and carbon accounts for more than 80% of the total mass of the filler, and the ratio of iron to carbon mass is 1-10:1; Among them, iron particles are cast iron scraps, metallic iron, carbon-containing metallic iron, carbon-containing sponge iron, steel, and iron-based alloy scrap particles with an iron content of 70% or more by weight; carbon particles It is an arbitrary proportion combination of one or more of activated carbon, coke, graphite, carbon fiber, coal, and fly ash; at the same time, a small amount of copper, aluminum, zinc and other metals can be added to the micro-electrolysis mixed particles and structured fillers during electrolysis One or more elements to enhance the effect of micro-electrolysis treatment, the amount added shall not exceed 10% of the total mass.

During iron-carbon micro-electrolysis reaction described in the present invention, can adopt continuous or discontinuous aeration mode, add oxidant mode or aeration and add oxidant joint use mode to change waste water property and strengthen micro-electrolysis treatment effect as required, aeration and/or The treatment of adding an oxidizing agent is performed during the iron-carbon micro-electrolysis reaction and/or after the iron-carbon micro-electrolysis reaction.

In the present invention, the heavy metal-containing smelting wastewater treated by the micro-electrolysis reaction is adjusted to a pH of 6-11 and then chemically flocculated to further remove and reduce pollution such as heavy metal ions and non-metallic pollution ions (such as arsenic and fluorine ions) in the wastewater In the process of chemical flocculation treatment, flocculants can be added to strengthen the flocculation effect. The added flocculants are one or more of inorganic flocculants and organic flocculants. The inorganic flocculants are calcium salts, aluminum salts, polyaluminum salts, iron salts, Polymerized iron salt, the organic flocculant is a polyacrylamide reagent, the amount of flocculant varies greatly according to the wastewater quality, the amount of inorganic flocculant ranges from 0-500 g/ ^m3 water, and the amount of organic flocculant ranges from 0-20g/ m ³ water.

Before or during the chemical flocculation treatment, the present invention changes the properties of wastewater and strengthens the chemical flocculation impurity removal effect by means of continuous and intermittent aeration and/or adding oxidants; chemical flocculation treatment is generally single-stage, but multi-stage treatment can also be used to improve Chemical flocculation and impurity removal effect.

The solid-liquid separation treatment in the present invention can adopt any combination of one or more methods in sedimentation separation, filtration, pressure filtration and membrane separation methods as required.

The gas that aeration adopts among the present invention is oxygen, air and oxygen-containing gas, and aeration rate is 0～3m ³ gas/m ^{3 water.min} ; The oxidizing agent that adds is hydrogen peroxide, peroxide, hypochlorous acid and salt and Ozone, the dosage is 0-100g/m ³ water.

The advantages of the present invention are: (1) The "micro-electrolysis-chemical flocculation coupling method" is used to treat smelting wastewater containing heavy metals, and the treatment process is simple; for smelting wastewater containing heavy metals, the micro-electrolysis method has a good treatment effect on heavy metal ions, but it is The effect of non-metallic pollution ions (such as arsenic, fluorine, etc.) is poor. The chemical flocculation method has a good effect on the treatment of low-concentration heavy metal ions and non-metallic pollution ions (such as arsenic, fluorine, etc.), but the treatment effect on high-concentration heavy metal ions is not ideal. , combining micro-electrolysis and chemical flocculation organically, removing most of the heavy metal ions through micro-electrolysis, creating conditions for flocculation treatment, and enhancing the treatment efficiency of micro-electrolysis through subsequent flocculation, the overall treatment effect is good, and these two methods are solved separately Even the use of wastewater can not make the wastewater treatment up to standard, and the effluent can meet the national first-level discharge standard or higher requirements. (2) Compared with the commonly used single lime neutralization method, the effluent water quality is guaranteed, and the amount of sediment can be significantly reduced. After the sediment is treated, it can be recycled and reused, and it can be used as a raw material for treatment or other raw materials again. (3) The treatment method and process of the present invention are simple, the treatment cost is low, the treatment efficiency is high, heavy metal resources can be recovered, and the treated wastewater can be recycled after reaching the standard, which can achieve a very good comprehensive utilization of resources.

the

Description of drawings

Fig. 1 is a process flow chart of the treatment method for smelting wastewater containing heavy metals.

Detailed ways

 The essence of the present invention will be further described below in conjunction with the accompanying drawings, but the content of the present invention is not limited thereto.

Example 1

Figure 1 is a flow chart of the micro-electrolysis-chemical flocculation process for treating smelting wastewater containing heavy metals. The production workshop of a large-scale copper sulfide smelter contains heavy metal wastewater. The wastewater is mainly the ground flushing water of the smelter production workshop. The wastewater volume is 1000t/d, the pH of the wastewater is 5-6, and the heavy metal content (mg/L) is: Cu: 20.66 , Zn: 4.53, Pb: 1.80, Cd: 5.60, As: 3.71. In the treatment test, the waste water was collected and settled in the sedimentation tank to remove particulate matter, then adjusted to pH=3.0-3.5 with sulfuric acid, and the pretreated waste water was transferred to the fixed-bed micro-electrolysis equipment for iron-carbon micro-electrolysis treatment, and aeration was carried out during the treatment process; the fixed bed It is composed of iron and carbon granular fillers and iron-carbon structured fillers (structured fillers account for 30% of the total mass of fillers). The iron-carbon mass ratio of iron-carbon structured fillers and iron-carbon granular fillers is 2:1, but iron-carbon structured fillers are 2% aluminum; wastewater treatment adopts three-stage continuous flow iron-carbon micro-electrolysis treatment, and the hydraulic retention of each stage is 20min. During micro-electrolysis, continuous aeration of 0.8m ³ /m ³ water is used. After micro-electrolysis, the wastewater Enter the aeration tank to adjust the pH to 9.0 with sodium hydroxide, then continue to aerate for 20 minutes, the aeration volume is 1.5 m ³ /m ³ water, so that most of the ferrous ions in the solution are converted into ferric ions, and then enter the flocculation sedimentation The pool is used for flocculation and sedimentation separation, the hydraulic retention time is 30min, the effluent pH=8.5-9.0, the metal content (mg/L) is: Cu: 0.084, Zn: 0.153, Pb: 0.042, Cd: 0.0331, As: 0.037, reaching The integrated wastewater discharge standard (GB8978-1966) requires that it can be used as production reuse water.

Example 2

The acid washing workshop of a copper sulfide smelter contains heavy metal pickling wastewater, the wastewater volume is 200t/d, the wastewater contains 6-8% sulfuric acid, and the heavy metal components (mg/L) are: Cu: 181.70, Zn: 28.27, Pb: 167.05, Cd: 15.60, As: 176.71, F: 319.23. In the treatment test, the wastewater was adjusted to pH=2.5 with lime, and the supernatant was transferred to rolling micro-electrolysis equipment (rolling bed) for iron-carbon micro-electrolysis treatment after static precipitation. The total mass of iron and carbon particles accounted for the total mass of fillers. 100%, the ratio of iron to carbon mass is 5:1, using continuous flow iron-carbon micro-electrolysis secondary treatment, each stage of hydraulic retention is 25min, after the end of micro-electrolysis, the wastewater enters the aeration flocculation tank, adopts continuous aeration, aeration The volume is 3m ³ /m ³ of water, the aeration time is 40min, and the pH is adjusted to 11.0 with milk of lime during aeration, and at the same time, 20g/m ³ of polyacrylamide with a molecular weight of 800 is added, and after aeration and flocculation, press filtration is carried out. Method for solid-liquid separation, the effluent metal content (mg/L) is: Cu: 0.086, Zn: 0.075, Pb: 0.12, total Cd: 0.0071, total Cr: 0.03, As: 0.059, F: 1, and the heavy metal index is lower than According to the first-level standard of comprehensive sewage discharge standard (GB8978-1966), the wastewater can be directly discharged or used as production reuse water after returning to pH=8.5-9.0.

Example 3

Production wastewater in the indium zinc production workshop of an indium zinc smelter, the wastewater volume is 50t/d, the wastewater pH is 2.5-3.0, and the heavy metal content (mg/L) is: Cu: 4.32, Zn: 543.56, Pb: 2.77, Cd: 5.58 , As: 5.992, F: 19.06. In the treatment test, there is no particulate matter in the wastewater, and the pH of the wastewater is 2.5-3.0, which meets the requirements of iron-carbon micro-electrolysis treatment. Therefore, the wastewater directly enters the bottom aeration fluidized electrolytic cell (aeration fluidized bed) for iron-carbon micro-electrolysis treatment. The sum of the total mass of iron and carbon particles accounts for 100% of the total mass of the filler, and the ratio of iron to carbon mass is 1:1-2:1. Continuous flow iron-carbon micro-electrolysis is used for primary treatment, and the hydraulic retention is 30min. Continuous micro-electrolysis Aeration, the aeration rate is 3.0m ³ /m ³ water, and at the same time most of the ferrous ions in the solution have been converted into ferric ions. Therefore, after the micro-electrolysis is completed, the wastewater is adjusted to pH = 8.5-9.0 with sodium hydroxide + sodium carbonate (ratio 1:1) in the flocculation tank, and then the amount of 3# flocculant (polyacrylamide) is added to 10g/ m ³ Water, after stirring and reacting for 10 minutes, use a filter press for solid-liquid separation. The solid-liquid separation filter residue contains high heavy metals and can be used as a resource; the pH of the solid-liquid separation water is about 8.7, and the heavy metal content (mg/L) of the water is: Cu: 0.10, Zn: 0.093, Pb: 0.12, Cd: 0.0051, As: 0.21, the heavy metal index is lower than the requirements of the first-level standard of comprehensive sewage discharge standard (GB8978-1966), it can be used as production reuse water, and the effluent is re-used by nanofiltration and reverse osmosis Treatment, the heavy metal content (mg/L) of reverse osmosis effluent is: pH6-8, Cu≤0.05, Zn≤0.05, Pb≤0.05 Cd≤0.005 As≤0.05, reaching the surface water environmental quality standard (GB2828-2002) Class III Requirements, can all be reused in production.

Example 4: The waste water for washing the floor of a medium-sized nickel smelter plant workshop, the waste water volume is 500t/d, the pH of the waste water is 6-6.5, and the heavy metal content (mg/L) is: Ni: 15.33, Cu: 14.21, Co: 9.9. In the treatment test, the wastewater was passed through a 200-mesh sieve to remove particulate impurities, and then the pH was adjusted to 3.5-4.0 with waste sulfuric acid. The pretreated wastewater was transferred to the iron-carbon structured packing bed for iron-carbon micro-electrolysis treatment. The iron-carbon micro-electrolysis structured packing was Ф30×20mm, short-column type hollow (Ф20×20mm) high-carbon sponge iron filler, the inside of the filler is microporous, the total mass of iron and carbon particles accounts for 90% of the total mass of the filler (the rest is impurities), of which the mass of carbon particles accounts for The total mass of the filler is 20%, and the three-stage ^treatment of continuous flow iron-carbon ^micro -electrolysis is adopted. The hydraulic retention of each stage is 15min. Use sodium hydroxide to adjust the pH of the flocculation tank to 8.5-9, then add polyaluminum sulfate 200 g/m ³ water and polyacrylamide flocculant 2 g/ m ³ water, stir and react for 25 minutes, then enter the inclined plate sedimentation tank, and the water from the sedimentation tank is then Membrane separation method is used for solid-liquid separation treatment, the separated water has a pH of about 8.5, and the heavy metal content (mg/L) is: Ni: 0.0053, Cu: 0.054, Co: 0.0031, and the heavy metal content has reached the surface water environmental quality standard (GB2828) -2002) Class III requirements, can be fully reused in production, micro-electrolysis and flocculation tank sediment metal grade is high, returned to the smelting system for resource utilization.

Example 5

A lead-zinc smelting and smelting plant pickling wastewater, the wastewater volume is 150m3/h, the wastewater contains 4-6% sulfuric acid, and the metal components (mg/L) are: Zn: 145.80, Pb: 94.81, Cu: 3.96, Cd: 14.60, As: 376.71. In the treatment test, limestone powder was used to adjust the pH of the wastewater to 2.5-3.0. After the wastewater was press-filtered, the clear liquid wastewater was treated with iron-carbon micro-electrolysis. Continuous flow iron-carbon micro-electrolysis aeration was used for three-stage treatment, and the aeration volume was 0.8m3 /m3 water. The first and second stages are mixed beds of iron (cast iron chips) and carbon particles, the sum of the total mass of cast iron chips and activated carbon particles accounts for 100% of the total mass of the filler, the ratio of iron to carbon mass is 2:1, and the hydraulic retention of each stage is 15 minutes, the third stage is iron-carbon micro-electrolysis treatment using iron-carbon structured packing bed, the structured packing is the same as in Example 4, and the hydraulic retention is 20 minutes. After the micro-electrolysis, the wastewater enters the aeration tank to adjust the pH to 8.5-9.0 with milk of lime, then add hydrogen peroxide 10 g/m ³ water, aerate continuously for 10 minutes, and the aeration rate is 1 m ³ /m ³ water, so that the solution Ferrous ions are converted into ferric ions, and trivalent arsenic is converted into pentavalent arsenic, then enters the flocculation tank, then adds polyacrylamide 2g/ ^m3 water, stirs and reacts for 15 minutes, and uses the method of sedimentation separation for solid-liquid separation , the metal content (mg/L) in the effluent after solid-liquid separation is: Zn: 0.075, Pb: 0.093, Cu: 0.092, Cd: 0.0091, As: 0.079, and the heavy metal index is lower than the comprehensive sewage discharge standard (GB8978-1966) It can be used as production reuse water according to the requirements of the grade standard; the metal grade of micro-electrolysis and flocculation tank sediment is high, and it can be returned to the smelting system for resource utilization. The effluent treated by micro-electrolysis and flocculation is then treated by nanofiltration and reverse osmosis. The heavy metal content of the reverse osmosis effluent is lower than the Class III standard of the surface water environmental quality standard (GB2828-2002), and can be fully reused for production.

Claims (14)

1. a treatment method containing heavy metal smelting waste water, is characterized in that comprising the steps: (1) Pretreat the smelting wastewater containing heavy metals, remove particulate impurities in the wastewater, and adjust the pH value of the wastewater to 2.0-5.0; (2) Transfer the pretreated wastewater into the iron-carbon micro-electrolysis reactor, and perform single-stage or multi-stage iron-carbon micro-electrolysis reaction under acidic conditions. The residence time of each stage of micro-electrolysis reaction is 5-120min, and remove the most of the heavy metal ions; (3) Adjust the pH value of the wastewater treated in step (2) to 6-11, and perform single-stage or multi-stage chemical flocculation treatment with or without flocculant as required, wherein the dosage range of inorganic flocculants is 0- 500 g/m ³ , the dosage range of organic flocculant is 0-20g/m ³ ; (4) Solid-liquid separation is performed on the wastewater treated in step (3), and it is discharged and/or recycled as production water after the test reaches the standard. 2. The treatment method according to claim 1, characterized in that: one or more of the pretreatment methods such as grille, screening, aeration and grit settling, sedimentation and separation, adding flocculant flocculation and sedimentation are used to remove waste water. Particle impurities. 3. according to the described processing method of claim 1, it is characterized in that: iron-carbon micro-electrolysis reactor is based on iron-carbon micro-electrolysis reaction fixed bed, tumbling bed and fluidized bed one or more any combination . 4. according to the described processing method of claim 1 and 3, it is characterized in that: iron-carbon micro-electrolysis reaction bed is iron-carbon mixed particle bed and/or iron-carbon structured packing bed, wherein iron particle and carbon particle are total in iron-carbon mixed particle bed The sum of the mass accounts for more than 80% of the total mass of the filler, and the ratio of iron to carbon mass is 1-10:1; the total mass of iron and carbon in the iron-carbon structured packed bed accounts for more than 80% of the total mass of the filler, and the ratio of iron to carbon mass is 1-10:1. 5. according to the described processing method of claim 1 and 4, it is characterized in that: one or more elements in a small amount of copper, aluminum, zinc metal can be added in the micro-electrolysis mixed particles and the structured packing, and the addition amount does not exceed the total mass 10%. 6. The treatment method according to claims 1 and 4, characterized in that: the iron particles are cast iron scraps, metallic iron, carbon-containing metallic iron, carbon-containing sponge iron, steel, and iron-based alloys containing iron weight percentage ≥ 70% One or more combinations in any proportion of crumb particles; carbon particles are one or more combinations in any proportion of activated carbon, coke, graphite, carbon fiber, coal, and fly ash. 7. The treatment method according to claim 1, characterized in that: during the iron-carbon micro-electrolysis reaction process, continuous aeration or intermittent aeration treatment, and/or oxidant addition treatment are used to strengthen the micro-electrolysis to remove heavy metal ions. 8. The treatment method according to claim 7, characterized in that: the treatment of aeration and/or adding oxidant is carried out during the iron-carbon micro-electrolysis reaction and/or after the iron-carbon micro-electrolysis reaction. 9. The treatment method according to claim 1, characterized in that: a flocculant is added during the chemical flocculation treatment, and the flocculant is one or more of inorganic flocculants and organic flocculants. 10. The treatment method according to claim 9, characterized in that the inorganic flocculants are calcium salts, aluminum salts, polyaluminum salts, iron salts, and polyferric salts, and the organic flocculants are polyacrylamide agents. 11. The treatment method according to claim 1, characterized in that before or during the chemical flocculation treatment, the waste water is aerated and/or an oxidant is added for oxidation treatment to change the properties of the waste water. 12. The treatment method according to claim 8 or 11, characterized in that: the gas used for aeration during aeration treatment can be oxygen, air and oxygen-containing gas, and the aeration rate is 0~3m ³ /m ^{3 water.min} ; The added oxidants are hydrogen peroxide, peroxide, hypochlorous acid, salt, and ozone, and the dosage is 0-100g/m ³ water. 13. The treatment method according to claim 1, characterized in that: the solid-liquid separation treatment method is one or any combination of sedimentation separation, filtration, pressure filtration and membrane separation methods. 14. The treatment method according to claim 1, characterized in that it is used alone or as a treatment unit in the wastewater treatment process.