A method, system and application for treating heavy metal wastewater

Abstract

The present invention relates to the field of water treatment technology, and in particular to a method, system, and application for treating heavy metal wastewater. The method comprises: after the wastewater is homogenized, coarsely filtered, and ultrafiltered in sequence, the ultrafiltration product water is concentrated and separated into product water and concentrated water; the concentrated concentrated water is first subjected to iron-carbon micro-electrolysis treatment, and then separated into sludge and supernatant by precipitation; the supernatant is subjected to electrochemical oxidation-reduction treatment. The method can directly treat heavy metal wastewater without adjusting the pH value of the wastewater, realize the simultaneous removal of heavy metal ions and organic matter in the wastewater, and realize the standard discharge of wastewater; it also realizes the reuse of part of the wastewater, saves water resources, can be promoted and used, and has high economic value.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a method, system and application for treating heavy metal wastewater. Background Art

[0002] Heavy metal wastewater mainly refers to wastewater rich in metal ions such as copper, zinc, chromium, and nickel, which mainly comes from the electroplating industry and the metallurgical industry. Heavy metal wastewater has high heavy metal content, high toxicity, and great impact on the environment. Therefore, the discharge indicators of heavy metal wastewater are strictly required.

[0003] The electroplating industry is characterized by large amounts of wastewater, complex pollutant composition, and high salt content, which results in poor biochemical degradability of electroplating wastewater and difficulty in meeting wastewater treatment standards.

[0004] Metallurgical industry wastewater refers to wastewater discharged from the production process of the metallurgical industry, mainly from pickling wastewater, dust removal wastewater, coal gas and slag flushing wastewater, etc. Its characteristics are large amount of wastewater, many types of heavy metal ions and complex pollutant composition.

[0005] In the prior art, heavy metal wastewater is mainly treated by precipitation methods, such as hydroxide precipitation method and sulfide precipitation method. However, the above methods all require the wastewater to be pre-treated by adding alkali, and the pH of the wastewater is adjusted to neutral or alkaline before the heavy metals and organic matter in the wastewater are treated. The above water treatment methods not only consume a large amount of alkali, but also increase the burden of subsequent water treatment due to the introduction of alkali, and have poor economic feasibility.

[0006] In addition, the existing technology generally adopts a method of separately treating each ion in heavy metal wastewater, which has cumbersome treatment methods. In the process of wastewater treatment, chelating agents are added to form very stable complexes with heavy metal ions such as copper ions. It is difficult to remove the complexes using general flocculation and sedimentation methods, and it is impossible to achieve standard discharge of wastewater. Summary of the invention

[0007] In response to the above technical problems, the present invention provides a method, system, and application for treating heavy metal wastewater. The method can efficiently and simultaneously remove harmful metal ions and organic matter such as copper, zinc, chromium, and nickel in heavy metal wastewater, achieve standard discharge of each metal ion, and realize water reuse.

[0008] To solve the above technical problems, the embodiments of the present invention adopt the following technical solutions:

[0009] In a first aspect, an embodiment of the present invention provides a method for treating heavy metal wastewater, comprising: after the wastewater is homogenized, coarsely filtered, and ultrafiltered in sequence, ultrafiltration product water is concentrated to separate product water and concentrated water, and the product water is reused;

[0010] The concentrated concentrated water is first subjected to an iron-carbon micro-electrolysis treatment, and then separated into sludge and supernatant by precipitation, and the supernatant is subjected to an electrochemical oxidation-reduction treatment.

[0011] Compared with the prior art, the method for treating heavy metal wastewater provided by the embodiment of the present invention can directly treat heavy metal wastewater without adjusting the pH value of the wastewater or adding a precipitant, thereby reducing drug consumption and having low investment costs. It can achieve the simultaneous removal of heavy metal ions and organic matter such as copper, zinc, chromium, and nickel in the wastewater, achieve the standard discharge of wastewater, and also achieve the reuse of part of the wastewater, thus saving water resources. It can be promoted for use and has high economic value.

[0012] The heavy metal wastewater treatment method provided by the embodiment of the present invention removes part of the suspended matter and colloid in the wastewater through homogenization and coarse filtration, and then further removes the suspended matter and colloid in the wastewater through ultrafiltration to achieve fine filtration. The turbidity of the ultrafiltration water can be reduced to below 0.3NTU, and then it is concentrated, which can reduce the treatment amount of wastewater by iron-carbon electrolysis and electrochemical oxidation-reduction, improve the treatment efficiency, and reduce the working power consumption; the combination of iron-carbon electrolysis and electrochemical oxidation-reduction can simultaneously remove harmful metal ions and organic matter in the water, so that it meets the discharge standards, protects the ecological environment, and can also achieve partial recycling of heavy metal wastewater and save water resources.

[0013] Preferably, the concentrated water obtained by ultrafiltration is homogenized, coarsely filtered and ultrafiltered again in sequence.

[0014] Preferably, the treatment method further comprises exchanging the wastewater after the electrochemical oxidation-reduction treatment.

[0015] In a second aspect, an embodiment of the present invention provides a heavy metal wastewater treatment system, comprising:

[0016] Homogenizing tank;

[0017] An activated carbon filter, whose liquid inlet is connected to the liquid outlet pipe of the homogenizing tank, is used to preliminarily remove suspended matter in the wastewater;

[0018] A self-cleaning filter, the liquid inlet of which is connected to the filtrate outlet pipe of the activated carbon filter, for further removing suspended matter from the wastewater and preliminarily removing colloids;

[0019] An ultrafiltration device, whose liquid inlet is connected to the filtrate outlet pipe of the self-cleaning filter, is used to further remove suspended matter and colloids in the wastewater;

[0020] A concentration device, the liquid inlet of which is connected to the water outlet pipe of the ultrafiltration device, is used to preliminarily remove heavy metal ions and organic matter from the wastewater, and retain most of the heavy metal ions and organic matter in the concentrated water. The produced water can be recycled and reused in the electroplating industry and the metallurgical industry;

[0021] The iron-carbon micro-electrolysis cell has a liquid inlet connected to the concentrated water outlet pipe of the concentrator, and is used to degrade organic matter in the concentrated water obtained by ultrafiltration and reduce heavy metal ions; wherein the interior of the iron-carbon micro-electrolysis cell is sequentially provided with a coarse filler area, a fine filler area and a transition area according to the flow direction of the feed liquid; the iron-carbon micro-electrolysis cell is also connected to an aeration device and a dosing device through a pipeline;

[0022] A sedimentation tank, the liquid inlet of which is connected to the liquid outlet pipe of the iron-carbon micro-electrolysis cell, and is used to precipitate sludge and separate the supernatant;

[0023] An electrochemical redox tank, whose liquid inlet is connected to the supernatant outlet pipe of the sedimentation tank, is used to remove heavy metal ions and organic matter in the supernatant, wherein the interior of the electrochemical redox tank is provided with a filler area and a non-filler area in sequence from the outside to the inside; the filler area is used to accommodate catalytic fillers; the non-filler area is used to accommodate activated carbon; a pipeline for refluxing catalytic fillers is provided between the filler area of ​​the electrochemical redox tank and the iron-carbon micro-electrolysis cell; a sludge return pipeline is provided between the non-filler area of ​​the electrochemical redox tank and the sedimentation tank, which is used to reflux sludge precipitated in the non-filler area.

[0024] The heavy metal wastewater treatment system of the present invention is a combined system. The heavy metal wastewater flows from the homogenization tank into the activated carbon filter, the self-cleaning filter, the ultrafiltration device, the concentration device, the iron-carbon micro-electrolysis cell, the sedimentation tank and the electrochemical oxidation-reduction cell in sequence, which can make the heavy metal wastewater meet the discharge standards and can also realize partial recycling of the heavy metal wastewater, saving water resources.

[0025] In this system, the homogenization tank homogenizes the water quality and quantity in the wastewater; the activated carbon filter filters the suspended solids in the wastewater, and the activated carbon in the activated carbon filter can be placed in the coarse filler area and transition area of ​​the iron-carbon micro-electrolysis cell after being discarded, replacing the iron-carbon composite filler and playing a micro-electrolysis role. The discarded activated carbon can also be placed in the non-filler area of ​​the electrochemical redox cell to form countless tiny batteries and enhance the treatment effect of the electrochemical redox cell.

[0026] In combination with the second aspect, the above-mentioned heavy metal wastewater treatment system also includes a water quality exchanger, which is connected to the feed liquid outlet pipe of the electrochemical redox cell for further removing heavy metal ions and organic matter, wherein the concentrate water pipe of the water quality exchanger is connected to the coarse filling area of ​​the iron-carbon micro-electrolysis cell through a pipeline, which is used to input the concentrate water of the water quality exchanger into the coarse filling area of ​​the iron-carbon micro-electrolysis cell for further treatment.

[0027] In an embodiment of the present invention, the above-mentioned heavy metal wastewater treatment system can choose to add a water quality exchanger according to the quality of the water to be treated. For example, after the wastewater is treated from the homogenization tank in sequence through the above-mentioned activated carbon filter, self-cleaning filter, ultrafiltration device, concentration device, iron-carbon micro-electrolysis cell, sedimentation tank and electrochemical oxidation-reduction tank, if the discharged water quality has met the standards, then the above-mentioned heavy metal wastewater treatment system may not be installed with a water quality exchanger.

[0028] In an embodiment of the present invention, the water quality exchanger can be a resin exchanger, which acts as a terminal insurance to further process heavy metals and organic matter in the wastewater, avoid the problem of wastewater not meeting the standards due to fluctuations in wastewater quality, and ensure that the produced water meets the discharge standards; the concentrated water produced by the resin exchanger can be returned to the iron-carbon micro-electrolysis cell through a pipeline for further treatment.

[0029] Preferably, the concentration device is a reverse osmosis device or an evaporation device.

[0030] In the embodiment of the present invention, the ultrafiltration concentrated water is returned to the homogenization tank through the pipeline for further treatment; the ultrafiltration produced water flows into the reverse osmosis device or the evaporation device, and is separated into produced water and concentrated water in the reverse osmosis device or the evaporation device, and most of the organic matter and heavy metal ions are concentrated in the concentrated water, which can achieve the reduction of wastewater and reduce the investment scale of the subsequent water treatment system. For example, the produced water volume of the reverse osmosis device is 3 times the concentrated water volume, which can effectively achieve the purification, separation and concentration of water, and greatly reduce the subsequent wastewater treatment volume. At the same time, the concentration of organic matter and heavy metal ions increases the ion concentration and the conductivity, which is more conducive to improving the subsequent iron-carbon micro-electrolysis and electrochemical oxidation-reduction treatment efficiency, and reduces the power consumption of the iron-carbon micro-electrolysis cell and the redox electrolysis cell.

[0031] Preferably, the coarse filler area, the fine filler area and the transition area are divided by a carbon fiber mesh, a metal mesh or a plastic mesh.

[0032] In the embodiment of the present invention, the cross-flow of fillers loaded in the coarse filler area, the fine filler area and the transition area is avoided by segmentation with the carbon fiber mesh, the metal mesh or the plastic mesh.

[0033] Preferably, the coarse filler area is filled with iron-carbon composite fillers for micro-electrolysis reaction, degradation of organic matter and reduction of metal ions;

[0034] The fine filler area is used to load catalytic fillers, wherein the catalytic fillers activate the catalytic active sites of the catalyst in the acidic and aerated environment of the iron-carbon micro-electrolysis cell, thereby realizing the activation of the catalytic fillers;

[0035] The transition zone is used to intercept the catalytic filler accidentally overflowing from the fine filler zone;

[0036] The coarse filler area is connected to an aeration device via a gas pipeline for providing oxygen to the iron-carbon micro-electrolysis cell;

[0037] The coarse filler area is connected to a dosing device via a dosing pipeline for adding H2O2 to form a Fenton oxidation system.

[0038] In an embodiment of the present invention, the iron-carbon micro-electrolysis cell is divided into three independent areas: a coarse filling area, a fine filling area and a transition area. The coarse filling area is filled with iron-carbon composite fillers for micro-electrolysis reaction, degradation of organic matter and reduction of metal ions; the fine filling area is used to fill catalytic fillers, and the catalytic fillers are activated under the action of the iron-carbon micro-electrolysis cell; the transition zone is used to intercept catalytic fillers accidentally overflowing from the fine filling area.

[0039] In the iron-carbon micro-electrolysis cell, the iron filings in the iron-carbon composite filler have a comprehensive role in the electro-attachment of flocs, participation in catalytic reactions, coagulation with battery reaction products, adsorption of new flocs, and filtration of the bed. Among them, the main functions are redox and electro-attachment. The main components of the iron-carbon composite filler are iron and carbon. When it is immersed in an electrolyte solution, due to the electrode potential difference of 1.2V between Fe and C, countless micro-battery systems are formed, forming an electric field in the space of the iron-carbon micro-electrolysis cell, causing the anode reaction to generate a large amount of Fe 2+ After entering the wastewater, it is oxidized to Fe 3+ , forming a flocculant with high adsorption and flocculation activity. The cathode reaction produces a large amount of new ecological [H] and [O]. Under acidic conditions, these active ingredients can undergo redox reactions with many organic components in the wastewater, causing organic macromolecules to undergo chain scission degradation, thereby eliminating organic matter, especially the color of the wastewater, and improving the biodegradability of the wastewater. The cathode reaction consumes a large amount of H + A large amount of OH is generated - , which also increases the pH value of the wastewater.

[0040] When wastewater comes into contact with the iron-carbon composite filler, the following electrochemical reaction occurs:

[0041] Anode: Fe-2e—→Fe E0(Fe / Fe)=0.4V

[0042] Cathode: 2H + +2e—→H2 E0(H + / H2)=0V

[0043] When oxygen is present, the cathode reaction is as follows:

[0044] O2+4H + +4e—→2H2O E0(O2)=1.23V

[0045] O2+2H2O+4e—→4OH - E0(O2 / OH - )=0.41V

[0046] H2O2 is added through the dosing device to react with the anode of the iron-carbon micro-electrolysis cell to generate Fe 2+ Forming a catalyst that can catalyze the oxidation of organic matter. 2+ It forms a Fenton reagent oxidation system with H2O2 to catalyze the degradation of organic matter in wastewater.

[0047] In addition, the new eco-[H] generated by the cathode reaction can undergo redox reactions with many organic components in the wastewater, and can react with the chromophore groups in the organic intermediate molecules (such as azo groups) to decolorize them, thereby achieving catalytic degradation of organic matter.

[0048] The aeration device can be an aeration pump. The oxygen provided by the aeration pump realizes the iron-carbon aeration reaction and consumes a large amount of hydrogen ions, thereby increasing the pH value of the wastewater and creating conditions for subsequent catalytic oxidation treatment.

[0049] Preferably, a sludge discharge pipeline is provided at the lower end of the sedimentation tank for discharging sludge;

[0050] The upper end of the sedimentation tank is provided with a water outlet pipe for flowing the supernatant into the non-filling area of ​​the electrochemical redox tank.

[0051] In the embodiment of the present invention, the sedimentation tank can precipitate the heavy metals in the wastewater into the sludge to achieve the removal of heavy metal ions. After the sludge is discharged, dehydrated and dried, it can be treated in the conventional solid waste treatment method.

[0052] Preferably, the filler area of ​​the electrochemical redox cell is filled with catalytic fillers for catalytic degradation of organic matter; the slope of the filler area is 2%-5%;

[0053] The non-filler area of ​​the electrochemical redox cell is filled with activated carbon to form a microbattery.

[0054] A sludge return pipeline is provided between the non-filling area of ​​the electrochemical redox tank and the sedimentation tank, and is used to return the sludge precipitated in the non-filling area of ​​the electrochemical redox tank to the sedimentation tank.

[0055] In an embodiment of the present invention, the supernatant flows into the filler area and the non-filler area of ​​the electrochemical redox tank through the outlet pipe at the upper end of the sedimentation tank, and flows between the non-filler area and the filler area. Under the catalytic degradation of the catalytic filler in the filler area and the electrolysis of the microbatteries in the non-filler area and the electrochemical redox tank, the organic matter in the supernatant is catalytically degraded, and the heavy metal ions are reduced and precipitated into the sludge and the sludge is returned to the sedimentation tank through the sludge return pipeline, thereby realizing the degradation of organic matter in the wastewater and the removal of heavy metal ions.

[0056] In the implementation of the present invention, the electrochemical redox cell causes the organic matter and heavy metals in the supernatant obtained from the sedimentation tank to undergo a direct electrochemical reaction on the electrode, or utilizes the strong oxidizing active substances produced on the electrode surface to cause the organic matter and heavy metals to undergo a redox reaction and degrade them, and can also oxidize and degrade the organic matter under the catalysis of the catalytic filler; in addition to the direct reduction effect, the cathode of the electrochemical redox cell can also react with H + The discharge generates [H], which removes the color of the wastewater. When treating certain wastewaters, the electrochemical redox cell will also produce gases such as N2 and CO2, which play a role in flotation. In addition, during the above reaction in the electrochemical redox cell, iron ions or aluminum ions are easily formed at the anode, and further generate iron and aluminum hydroxy complexes. These complexes can remove impurities such as suspended matter or colloids in the wastewater and play a coagulation role.

[0057] In a third aspect, an embodiment of the present invention provides a method for water treatment using the heavy metal wastewater treatment system, wherein the wastewater to be treated is passed through the homogenization tank for homogenization treatment, and the wastewater after homogenization treatment is coarsely filtered through the activated carbon filter and the self-cleaning filter in sequence; then ultrafiltration is performed through the ultrafiltration device, and the ultrafiltration product water is separated into product water and concentrated water through the concentrator, and the concentrated water is passed through the iron-carbon micro-electrolysis cell, and micro-electrolysis treatment is performed in the coarse filler zone and the transition zone, and catalytic degradation treatment is performed in the fine filler zone, and the resulting wastewater is passed through the sedimentation device. The sedimentation tank is separated into sludge and supernatant, and the supernatant is passed into the electrochemical redox tank as wastewater and flows in the filler area and the non-filler area. After catalytic degradation in the filler area and micro-electrolysis in the non-filler area, the treated wastewater is obtained; driven by a water pump, the catalytic filler in the filler area of ​​the electrochemical redox tank is returned to the fine filler area of ​​the iron-carbon micro-electrolysis cell through a pipeline to activate the catalytic filler, and then driven by a water pump, the activated catalytic filler is returned to the filler area of ​​the electrochemical redox tank through a pipeline to realize the reuse of the catalytic filler.

[0058] In combination with the third aspect, the filling area of ​​the electrochemical redox cell is connected to the fine filling area of ​​the iron-carbon micro-electrolysis cell through a first pipeline. Under the drive of a water pump, the catalytic filler in the filling area of ​​the electrochemical redox cell is returned to the fine filling area of ​​the iron-carbon micro-electrolysis cell through the first pipeline. In the acidic and aerated environment of the iron-carbon micro-electrolysis cell, the catalytic active sites of the catalyst are activated to achieve activation of the catalytic filler; the fine filling area of ​​the iron-carbon micro-electrolysis cell is connected to the filling area of ​​the electrochemical redox cell through a second pipeline. Under the drive of a water pump, the activated catalytic filler is returned to the filling area of ​​the electrochemical redox cell through the second pipeline to achieve reuse of the catalytic filler.

[0059] In a fourth aspect, the present invention also provides the application of the above method and treatment system in the treatment of electroplating wastewater and metallurgical wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is a process flow chart of a heavy metal wastewater treatment system in Example 1 of the present invention;

[0061] Figure 2 It is a schematic diagram of the structure from the iron-carbon reduction tank to the electrochemical oxidation-reduction tank in the heavy metal wastewater treatment system in Example 1 of the present invention.

[0062] Homogenizing tank 1, activated carbon filter 2, self-cleaning filter 3, ultrafiltration device 4, outlet pipe 41, ultrafiltration concentrated water return pipeline 42, concentrating device 5, iron-carbon micro-electrolysis cell 6, aeration pump 61, dosing system 62, sedimentation tank 7, outlet pipe 71, sludge discharge pipeline 72, electrochemical redox tank 8, sludge return pipeline 81, first pipeline 82, second pipeline 83, water quality exchanger 9, third pipeline 91. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0064] Example 1

[0065] This embodiment provides a heavy metal wastewater treatment system, and its process flow chart is as follows: Figure 1 As shown:

[0066] The heavy metal wastewater enters the homogenization tank 1, and after the water quality and water quantity in the wastewater are homogenized, it flows into the activated carbon filter 2, and the suspended matter in the wastewater is adsorbed by the activated carbon, and then flows into the self-cleaning filter 3, and the suspended matter and colloid in the wastewater are filtered, and then flows into the ultrafiltration device 4, and the suspended matter and colloid in the wastewater are further removed in the ultrafiltration device 4, and the concentrated water obtained by ultrafiltration is returned to the homogenization tank 1 through the ultrafiltration concentrated water return pipeline 42 for further treatment, and the produced water obtained by ultrafiltration flows into the concentration device 5 through the outlet pipe 41;

[0067] The produced water obtained by ultrafiltration is separated into produced water and concentrated water in the concentration device 5, and the produced water is reused, saving water resources; the concentrated water obtained by ultrafiltration enters the iron-carbon micro-electrolysis cell 6 to degrade organic matter and heavy metal ions in the wastewater, wherein the wastewater acts as an electrolyte and forms countless micro-batteries with the iron-carbon composite material, and the wastewater is treated by the discharge of the cathode and anode of the micro-battery, thereby electrochemically degrading the organic matter and heavy metal ions in the wastewater; the oxygen provided by the aeration pump 61 realizes the iron-carbon aeration reaction, consumes a large amount of hydrogen ions in the wastewater, increases the pH value of the wastewater, and creates conditions for subsequent catalytic oxidation treatment; the H2O2 added by the dosing device 62 forms a Fenton oxidation system with the iron-carbon composite material, catalytically degrading organic matter, such as oxidizing carboxylic acids, alcohols, and esters to inorganic states. The iron-carbon composite material can also adsorb and flocculate tiny particles, metal ions, and organic macromolecules in the wastewater;

[0068] The wastewater treated by the iron-carbon micro-electrolysis cell 6 flows into the sedimentation tank 7, and the heavy metal ions are precipitated into sludge in the sedimentation tank 7. After being discharged from the sludge discharge pipeline 72, it is dehydrated and dried; the supernatant flows into the electrochemical redox tank 8 through the outlet pipe 71, and flows in the filler area and the non-filler area, and organic matter is degraded under the catalysis of the catalytic filler in the filler area of ​​the electrochemical redox tank 8, and the heavy metal ions are reduced under the action of micro-electrolysis in the non-filler area, so that the heavy metal ions are precipitated into sludge at the bottom of the non-filler area of ​​the electrochemical redox tank 8, and the sludge in the non-filler area is returned to the sedimentation tank through the sludge return pipeline 81 for further treatment;

[0069] The effluent treated by the electrochemical redox tank 8 flows into the water exchanger 9 through the outlet pipe. After further adsorption of metal ions and organic matter by the water exchanger 9, the produced water of the water exchanger meets the discharge standards. The concentrated water of the water exchanger flows back to the coarse filler area of ​​the iron-carbon micro-electrolysis cell through the third pipeline 91 for further treatment.

[0070] Figure 2 Schematic diagram of the structure of the iron-carbon micro-electrolysis cell to the electrochemical oxidation-reduction cell in the heavy metal wastewater treatment system of the present invention, wherein:

[0071] The catalytic filler loaded in the filler area in the electrochemical redox cell 8 is transported to the fine filler area of ​​the iron-carbon electrolytic cell through the first pipeline 82 under the action of a water pump, and the catalytic filler is activated in the iron-carbon electrolytic cell. The activated catalytic filler is transported to the filler area of ​​the electrochemical redox cell through the second pipeline 83 under the action of a water pump, and is used to catalytically degrade organic matter again, thereby improving the catalytic efficiency of the catalytic filler and realizing the reuse of the catalytic filler.

[0072] In order to better illustrate the present invention, further explanation is given below through specific embodiments.

[0073] Example 2

[0074] The embodiment of the present invention provides a process for treating electroplating industry wastewater using the heavy metal wastewater treatment system shown in Example 1:

[0075] 20m 3 / h of electroplating industry wastewater first enters the homogenization tank, and then flows through the activated carbon filter, in which more than 90% of suspended solids and more than 10% of organic matter can be removed. The wastewater is then transported to the self-cleaning filter and ultrafiltration device. After ultrafiltration, the turbidity of the produced water can be ≤0.3NTU. The ultrafiltration concentrated water is returned to the homogenization tank for further treatment; the ultrafiltration produced water enters the reverse osmosis device and is concentrated 4 times. The reverse osmosis membrane has a heavy metal retention rate of more than 99.9% in the water. The reverse osmosis produced water is reused in production, and the reverse osmosis concentrated water enters the iron-carbon Micro-electrolysis cell, in the iron-carbon micro-electrolysis cell, the organic matter and heavy metal ions are removed simultaneously, among which the organic matter removal rate can reach 30%-50%, and the copper, zinc, chromium, and nickel metal ion removal rate can reach 50%-90%. The wastewater treated by the iron-carbon micro-electrolysis cell enters the sedimentation tank to separate into supernatant and sludge. The supernatant enters the electrochemical oxidation-reduction cell. After electrochemical reduction, more than 80%-99% of organic matter can be removed, and more than 90-99% of copper, zinc, chromium, nickel and other heavy metal ions can be removed. The measured values ​​of COD, total copper, total copper, total nickel, total chromium, total zinc and pH of the wastewater are shown in Table 1.

[0076] Table 1 Main data indicators

[0077]

[0078] As can be seen from Table 1, after the wastewater is treated by the heavy metal wastewater treatment system of the present invention, the copper, zinc, chromium, nickel metal ions and organic pollutants in the wastewater have reached the discharge standard and can be discharged directly without further treatment by a water quality exchanger.

[0079] Example 3

[0080] The embodiment of the present invention provides a process for treating wastewater containing copper, zinc, chromium, nickel, etc. (the wastewater in Embodiment 2) by using the heavy metal wastewater treatment system shown in Embodiment 1:

[0081] 50m 3 / hWastewater containing copper, zinc, chromium, nickel, etc. first enters the homogenization tank, and then flows through the activated carbon filter, in which more than 90% of suspended solids and more than 10% of organic matter can be removed. The wastewater is then transported to the self-cleaning filter and ultrafiltration device. After ultrafiltration, the turbidity of the produced water can be ≤0.3NTU. The concentrated ultrafiltration water is returned to the homogenization tank for further treatment; the ultrafiltration produced water enters the evaporation device for 4 times of concentration, and the evaporated condensed water is reused in production. The evaporated concentrated water enters the iron-carbon micro-electrolysis cell. The electrolytic cell achieves the simultaneous removal of organic matter and heavy metal ions, among which the organic matter removal rate can reach 30%-50%, and the removal rate of copper, zinc, chromium, and nickel metal ions can reach 50%-90%. The wastewater treated in the iron-carbon micro-electrolytic cell enters the sedimentation separation into supernatant and sludge, and the supernatant enters the electrochemical oxidation-reduction cell. Under the action of electrochemical reduction, more than 80%-99% of organic matter can be removed, and more than 90-99% of copper, zinc, chromium, nickel and other heavy metal ions can be removed. The effluent of the electrochemical oxidation-reduction cell enters the resin exchanger for further treatment. The measured values ​​of COD, total copper, total copper, total nickel, total chromium, total zinc and pH of the wastewater are shown in Table 2.

[0082] Table 2 Main data indicators

[0083]

[0084] As can be seen from Table 2, the iron-carbon micro-electrolysis cell, electrochemical redox cell and resin exchanger after the concentration device all have good metal ion removal effects, and the electrochemical redox treatment of organic matter is effective. The resin exchanger can further remove metal ions and organic matter in the wastewater. Multivalent metal ions are adsorbed by the resin, and copper, zinc, chromium, nickel metal ions and organic pollutants in the produced water have reached the discharge standards, achieving complete removal of metal ions in the wastewater.

[0085] Example 4

[0086] After the heavy metal wastewater treatment system in Example 1 was operated for 1 month (wastewater in Example 2), the comparative organic matter removal effect is shown in Table 3 below.

[0087] Table 3 Effect comparison

[0088] name Dwell time Effect Before regeneration and activation of catalytic filler 1h COD removal rate 85% After the catalytic filler is regenerated and activated 1h COD removal rate: 93%

[0089] From Table 3, we can see that before the catalytic filler is regenerated and activated, the removal efficiency of organic matter is 85%; after the catalytic filler is activated, the removal efficiency of organic matter is 93%. It can be seen that the activation of the catalytic filler can increase the removal efficiency of organic matter, realize the reuse of the catalytic filler, and save economic costs.

[0090] Comparative Example 1

[0091] The wastewater containing copper, zinc, chromium, nickel metal ions and organic matter (the wastewater in Example 2) is treated by alkaline chemical precipitation, sulfide chemical precipitation or heavy metal capture agent precipitation methods in the prior art.

[0092] 20m 3 / h Wastewater containing copper, zinc, chromium, and nickel metal ions first enters the regulating tank to adjust the water quality and water quantity, and then is pumped to the pH regulating tank. The metal ions in the water will generate hydroxide precipitation. The wastewater enters the precipitation reaction tank. Coagulants and heavy metal capture agents are added in the sedimentation tank. The heavy metals in the water will react with the capture agent and precipitate. Finally, the hydroxide precipitation and heavy metal capture agent precipitation are separated into solid and liquid in the sedimentation tank. The pH of the effluent from the sedimentation tank is adjusted to neutral, and then filtered through sand filtration and activated carbon filter before discharge. The measured values ​​of COD, total copper, total copper, total nickel, total chromium, total zinc and pH of the wastewater are shown in Table 4.

[0093] Table 4 Main data indicators

[0094]

[0095] It can be seen from Table 4 that the organic matter removal rate of heavy metal wastewater treatment in the prior art is 620 mg / L, that is, the organic matter removal rate is low and the treated wastewater cannot meet the discharge standards.

[0096] Comparative Example 2

[0097] In the heavy metal wastewater treatment system of Example 1, the concentration device is removed, and then the wastewater is treated. ( Wastewater in Example 2 ) The main data indicators of processing and detection are shown in Table 5.

[0098] Table 5 Main data indicators

[0099]

[0100] As can be seen from Table 5, the measured values ​​of COD, total copper, total copper, total nickel, total chromium, total zinc and pH of the iron-carbon micro-electrolysis effluent without a concentrator and the electrochemical oxidation-reduction effluent are very close. It can be seen that the lack of a concentrator will not affect the treatment effect of organic matter and heavy metals, but will only increase the scale of subsequent treatment equipment and fail to achieve water resource recovery.

[0101] Comparative Example 3

[0102] In the heavy metal wastewater treatment system of Example 1, the iron-carbon micro-electrolysis cell and the sedimentation tank are removed, and then the wastewater (wastewater of Example 2) is treated and the main data indicators are detected.

[0103] 50m 3 / hWastewater containing copper, zinc, chromium, nickel, etc. first enters the homogenization tank, then flows through the activated carbon filter, in which more than 90% of suspended solids and more than 10% of organic matter can be removed, and the wastewater is then transported to the self-cleaning filter and ultrafiltration device. After ultrafiltration, the turbidity of the produced water can be ≤0.3NTU, and the ultrafiltration concentrated water is returned to the homogenization tank for further treatment; the ultrafiltration produced water enters the evaporation device for 4 times of concentration, and the evaporated condensed water is reused in production. The evaporated concentrated water enters the electrochemical oxidation-reduction device, and the organic matter can be removed by more than 80%-99% through electrochemical action, and copper, zinc, chromium, nickel and other heavy metal ions can be removed by more than 90-99%. The measured values ​​of COD, total copper, total copper, total nickel, total chromium, total zinc and pH of the wastewater are shown in Table 6.

[0104] Table 6 Main data indicators

[0105]

[0106] As shown in Table 6, the COD of the electrochemical oxidation-reduction pool water is 97 mg / L, the total copper is 43 mg / L, the total nickel is 20 mg / L, the total chromium is 3.40 mg / L, and the total zinc is 160 mg / L. It can be seen that the effluent after the electrochemical oxidation-reduction treatment of the wastewater cannot meet the discharge requirements. Only when it enters the resin exchanger, the multivalent metal ions are adsorbed by the resin, and the copper, zinc, chromium, and nickel metal ions in the produced water can meet the discharge standards, but the organic pollutants still cannot meet the discharge standards.

[0107] Therefore, the water treatment system of the present invention cannot remove the iron-carbon micro-electrolysis cell and the electrochemical oxidation-reduction cell. Only with the coordinated cooperation of the iron-carbon micro-electrolysis cell and the electrochemical oxidation-reduction cell can the treatment of organic matter and heavy metal ions in the wastewater meet the wastewater discharge standards.

[0108] Comparative Example 4

[0109] The electrochemical oxidation-reduction tank is removed from the heavy metal wastewater treatment system of Example 1, and then the wastewater (wastewater of Example 2) is treated and the main data indicators are detected.

[0110] 50m 3 / hWastewater containing copper, zinc, chromium, nickel, etc. first enters the homogenization tank, then flows through the activated carbon filter, in which more than 90% of suspended solids and more than 10% of organic matter can be removed, and the wastewater is then transported to the self-cleaning filter and ultrafiltration device. After ultrafiltration, the turbidity of the produced water is ≤0.3NTU, and the ultrafiltration concentrated water is returned to the homogenization tank for further treatment; the ultrafiltration produced water enters the evaporation device for 4 times of concentration, and the evaporated condensed water is reused in production. The evaporated concentrated liquid enters the iron-carbon micro-electrolysis tank and the sedimentation tank, and the organic matter and heavy metal ions are removed synchronously in the iron-carbon micro-electrolysis tank, among which the organic matter removal rate can reach 30%-50%, and the copper, zinc, chromium, and nickel metal ion removal rate can reach 50%-90%. The supernatant of the sedimentation tank enters the resin exchanger to further remove organic matter and metal ions. The measured values ​​of COD, total copper, total copper, total nickel, total chromium, total zinc and pH of the wastewater are shown in Table 7.

[0111] Table 7 Main data indicators

[0112]

[0113] As can be seen from Table 7, the polyvalent metal ions are adsorbed by the resin, and the concentration of copper, zinc, chromium, and nickel metal ions in the produced water is 0 mg / L, which meets the discharge standard. However, the organic pollutants in the produced water are 1460 mg / L, that is, the water treatment system lacks an electrochemical redox tank, and the organic matter still cannot meet the discharge standard. In addition, the absence of an electrochemical redox tank will increase the processing load of the resin exchanger, thereby posing the risk of unqualified metal ion emission indicators.

[0114] Summary: The experimental data of Comparative Example 1 and Examples 1-2 show that compared with the prior art, the heavy metal wastewater treatment system of the present invention does not require pre-adjustment of the wastewater pH value or the introduction of a precipitant, thereby reducing drug consumption costs and having low investment costs. Since the pH and solubility product of different metal ion precipitations are different, the prior art usually performs a separate precipitation treatment on a certain type of metal ion wastewater, and then mixes them after treatment. However, the present invention can achieve mixed treatment of wastewater containing different metal ions, and achieve simultaneous removal of metal ions and organic matter such as copper, zinc, chromium, and nickel in the wastewater, thereby achieving standard discharge of wastewater, and also achieving the reuse of part of the wastewater, saving water resources, having a broad space for use, and achieving better water quality standards for the treated effluent.

[0115] The experimental data of Comparative Examples 2-5 and Examples 2-3 show that the heavy metal wastewater treatment system of the present invention must include an iron-carbon micro-electrolysis cell or an electrochemical oxidation-reduction cell to efficiently and synchronously remove harmful heavy metal ions in water, solve the technical problem that each metal ion cannot be synchronously removed during water treatment in the prior art, and achieve the standard discharge of organic matter. Lack of an iron-carbon micro-electrolysis cell or an electrochemical oxidation-reduction cell cannot achieve the standard discharge of organic matter and heavy metal ions in wastewater. Therefore, the heavy metal wastewater treatment system of the present invention cannot lack an iron-carbon micro-electrolysis cell and an electrochemical oxidation-reduction cell. Only with the coordinated cooperation of the iron-carbon micro-electrolysis cell and the electrochemical oxidation-reduction cell can the treatment of organic matter and heavy metal ions in wastewater reach the wastewater discharge standard.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A heavy metal wastewater treatment system, characterized in that: include: Homogenizing tank; An activated carbon filter, the liquid inlet of which is connected to the liquid outlet pipe of the homogenizing tank; A self-cleaning filter, the liquid inlet of which is connected to the filtrate outlet pipe of the activated carbon filter; An ultrafiltration device, the liquid inlet of which is connected to the filtrate outlet pipe of the self-cleaning filter; A concentrator, whose liquid inlet is connected to the water outlet pipe of the ultrafiltration device; The iron-carbon micro-electrolysis cell has a liquid inlet connected to the concentrated water outlet pipe of the concentrator; wherein the interior of the iron-carbon micro-electrolysis cell is provided with a coarse filler area, a fine filler area and a transition area in sequence according to the flow direction of the feed liquid; the iron-carbon micro-electrolysis cell is also connected to an aeration device and a dosing device through a pipeline; A sedimentation tank, the liquid inlet of which is connected to the liquid outlet pipe of the iron-carbon micro-electrolysis cell, and is used to precipitate sludge and separate the supernatant; An electrochemical redox tank, wherein the liquid inlet is connected to the supernatant outlet pipe of the sedimentation tank; the interior of the electrochemical redox tank is provided with a filling area and a non-filling area in sequence from the outside to the inside; the filling area is used to accommodate catalytic filling; the non-filling area is used to accommodate activated carbon; a pipeline for refluxing catalytic filling is provided between the filling area of ​​the electrochemical redox tank and the iron-carbon micro-electrolysis cell; a sludge return pipeline is provided between the non-filling area of ​​the electrochemical redox tank and the sedimentation tank, which is used to reflux sludge precipitated in the non-filling area.

2. The heavy metal wastewater treatment system according to claim 1, characterized in that: It also includes a water exchanger; the water exchanger is connected to the feed liquid outlet pipe of the electrochemical redox cell, wherein the concentrated water pipe of the water exchanger is connected to the coarse filling area of ​​the iron-carbon micro-electrolysis cell through a pipeline, which is used to input the concentrated water of the water exchanger into the coarse filling area of ​​the iron-carbon micro-electrolysis cell for further treatment.

3. The heavy metal wastewater treatment system according to claim 1, characterized in that: The concentration device is a reverse osmosis device or an evaporation device.

4. The heavy metal wastewater treatment system according to claim 1, characterized in that: The coarse filler area, the fine filler area and the transition area are divided by a carbon fiber mesh, a metal mesh or a plastic mesh; The coarse filler area is filled with iron-carbon composite fillers for micro-electrolysis reaction, degradation of organic matter and reduction of metal ions; The fine filler area is used to load catalytic fillers; The transition zone is used to intercept the catalytic filler accidentally overflowing from the fine filler zone; The coarse filler area is connected to an aeration device via a gas pipeline for providing oxygen to the iron-carbon micro-electrolysis cell; The coarse filler area is connected to a dosing device via a dosing pipeline for adding H2O2 to form a Fenton oxidation system.

5. The heavy metal wastewater treatment system according to claim 1, characterized in that: A sludge discharge pipeline is provided at the lower end of the sedimentation tank for discharging sludge; The upper end of the sedimentation tank is provided with a water outlet pipeline for flowing the supernatant into the non-filling area of ​​the electrochemical redox tank; The slope of the packing area of ​​the electrochemical redox cell is 2%-5%; A sludge return pipeline is arranged between the non-filling area of ​​the electrochemical redox tank and the sedimentation tank, and is used to return the sludge precipitated in the non-filling area of ​​the electrochemical redox tank to the sedimentation tank.

6. A method for water treatment using the heavy metal wastewater treatment system according to any one of claims 1 to 5, characterized in that: The wastewater to be treated is passed into the homogenization tank for homogenization treatment, and the wastewater after homogenization treatment is coarsely filtered through the activated carbon filter and the self-cleaning filter in sequence; then ultrafiltration is performed through the ultrafiltration device, and the ultrafiltration product water is separated into product water and concentrated water through the concentrator, and the concentrated water is passed into the iron-carbon micro-electrolysis cell, and micro-electrolysis treatment is performed in the coarse filling area and the transition area, and catalytic degradation treatment is performed in the fine filling area, and the resulting wastewater is passed into the sedimentation tank to be separated into sludge and supernatant, and the supernatant is passed into the electrochemical redox tank and flows in the filling area and the non-filling area, and the treated wastewater is obtained after catalytic degradation in the filling area and micro-electrolysis in the non-filling area; under the drive of a water pump, the catalytic filler in the filling area of ​​the electrochemical redox tank is returned to the fine filling area of ​​the iron-carbon micro-electrolysis cell through a pipeline to activate the catalytic filler, and then the activated catalytic filler is returned to the filling area of ​​the electrochemical redox tank through a pipeline under the drive of the water pump, so as to realize the reuse of the catalytic filler.

7. Use of the water treatment system according to any one of claims 1 to 5 or the method according to claim 6 in the treatment of electroplating wastewater and metallurgical wastewater.

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