Pretreatment method of electrophoresis wastewater

Abstract

The invention discloses a pretreatment method of electrophoresis wastewater, which is characterized in that the electrophoresis wastewater is subjected to electrochemical treatment in an electrochemical reactor to obtain treated electrophoresis wastewater. Wherein the material of an anode plate in the electrochemical reactor comprises at least one of ruthenium iridium titanium, platinum titanium, iridium tantalum titanium, diamond, 316L stainless steel and a titanium plate; and the material of the cathode plate in the electrochemical reactor comprises at least one of 316L stainless steel, foamed nickel, a titanium mesh and a titanium plate. According to the pretreatment method of the electrophoresis wastewater, the sludge output is reduced, secondary pollution is avoided, the wastewater treatment effect is efficient and stable, and the treatment cost of the electrophoresis wastewater is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a pretreatment method for electrophoresis wastewater. Background Art

[0002] Electrophoretic coating is a special coating film formation method developed in the past 30 years. It is the most practical construction process for water-based paints. It has the characteristics of water solubility, non-toxicity, easy automation control, uniform coating, high film hardness, corrosion resistance and impact resistance. It has been widely used in the fields of automobiles, building materials, hardware, home appliances, instruments, agricultural machinery, etc.

[0003] At present, the automobile industry is developing rapidly, and the electrophoretic coating production process plays an important role in the automobile industry. During electrophoretic coating, the painted car body needs to be rinsed with a large amount of water to remove the floating paint and sediment attached to it. The water after rinsing is called electrophoretic wastewater. The large amount of electrophoretic wastewater generated not only increases the production cost, but also causes environmental pollution. The electrophoretic wastewater in the automobile industry contains a large amount of resin, pigment, filler, organic solvent, etc. These substances exist in the wastewater in the form of colloidal particles or suspended matter, showing high indicators such as COD, SS, chromaticity, many types of pollutants, complex wastewater composition, large discharge volume, large changes in water quality, irregular discharge, poor biodegradability, and difficult to degrade and treat.

[0004] Therefore, there is an urgent need to develop a low-cost, efficient and stable pretreatment method for electrophoresis wastewater. Summary of the invention

[0005] The present invention is based on the inventor's discovery and understanding of the following facts and problems: the current pretreatment method for electrophoresis wastewater is to mix electrophoresis wastewater, spray painting wastewater, etc. in proportion, and then directly perform coagulation and sedimentation treatment on the mixed wastewater. Although this process has the characteristics of low energy consumption, moderate operating costs, and low investment, it requires the addition of a large amount of chemicals, and a large amount of sludge will be generated during the treatment process. Sludge is a solid waste with a high treatment cost, and the effluent water quality is unstable, it is difficult to meet the discharge standards, and the treatment effect is not ideal.

[0006] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, the embodiment of the present invention proposes a pretreatment method for electrophoresis wastewater, which reduces the amount of sludge generated, has no secondary pollution, and has a high efficiency and stable wastewater treatment effect, effectively reducing the comprehensive treatment cost of electrophoresis wastewater.

[0007] The pretreatment method for electrophoresis wastewater of the embodiment of the present invention performs electrochemical treatment on the electrophoresis wastewater in an electrochemical reactor to obtain treated electrophoresis wastewater.

[0008] Advantages and technical effects of the electrophoresis wastewater pretreatment method according to the embodiment of the present invention:

[0009] 1. The pretreatment method of the embodiment of the present invention pretreats the electrophoresis wastewater in an electrochemical reactor, and the positively charged organic matter in the electrophoresis wastewater undergoes a reduction reaction on the cathode, thereby electrophoretically depositing on the cathode, thereby achieving pretreatment of the electrophoresis wastewater and reducing the COD in the wastewater;

[0010] 2. The pretreatment method of the embodiment of the present invention does not require the introduction of flocculants and does not produce sludge. It adopts the method of electrophoretic deposition coupled with electrochemical oxidation to pretreat the automobile electrophoretic wastewater. The treatment method has simple steps and low implementation costs. At the same time, it has good treatment effects and avoids the addition of large amounts of chemical agents for coagulation and precipitation in existing pretreatment technologies, greatly reducing the amount of sludge generated, effectively reducing the treatment cost of automobile electrophoretic wastewater, and achieving the purpose of reducing pollution and carbon emissions by treating electrophoretic wastewater.

[0011] In some embodiments, the pH value of the electrophoresis wastewater after adjustment is 1.5-9.

[0012] In some embodiments, the material of the anode plate in the electrochemical reactor includes at least one of ruthenium-iridium-titanium, platinum-titanium, iridium-tantalum-titanium, diamond, 316L stainless steel, and titanium plate.

[0013] In some embodiments, the material of the cathode plate in the electrochemical reactor includes at least one of 316L stainless steel, nickel foam, titanium mesh, and titanium plate.

[0014] In some embodiments, the material of the anode plate in the electrochemical reactor is diamond, and the material of the cathode plate is 316L stainless steel.

[0015] In some embodiments, in the electrochemical reactor, the distance between the cathode and the anode is 3-10 mm.

[0016] In some embodiments, the voltage of the electrochemical treatment is 15-80V.

[0017] In some embodiments, the voltage of the electrochemical treatment is a DC constant voltage.

[0018] In some embodiments, a magnetic stirrer is used in the electrochemical reactor for magnetic stirring, and the stirring speed is 600-1000 rpm.

[0019] In some embodiments, the temperature of the electrochemical treatment is 10-30° C., and the time of the electrochemical treatment is 30-165 min. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1It is a schematic diagram of the principle of the electrophoresis wastewater pretreatment method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0022] The pretreatment method for electrophoresis wastewater of the embodiment of the present invention performs electrochemical treatment on the electrophoresis wastewater in an electrochemical reactor to obtain treated electrophoresis wastewater.

[0023] like Figure 1 As shown, the pretreatment method of electrophoretic wastewater in an embodiment of the present invention pretreats the electrophoretic wastewater in an electrochemical reactor, and the positively charged organic matter in the electrophoretic wastewater undergoes a reduction reaction on the cathode, thereby being electrophoretically deposited on the cathode, thereby achieving pretreatment of the electrophoretic wastewater and reducing the COD in the wastewater.

[0024] The pretreatment method of the embodiment of the present invention does not require the introduction of flocculants and does not produce sludge. It adopts the method of electrophoretic deposition coupled with electrochemical oxidation to pretreat the automobile electrophoretic wastewater. The treatment method has simple steps and low implementation costs. At the same time, it has good treatment effects and avoids the addition of large amounts of chemical agents for coagulation and precipitation in existing pretreatment technologies. It greatly reduces the amount of sludge generated, effectively reduces the comprehensive treatment cost of automobile electrophoretic wastewater, and achieves the purpose of reducing pollution and carbon emissions by treating electrophoretic wastewater.

[0025] In some embodiments, the pH value of the electrophoresis wastewater after adjustment is 1.5-9, preferably 1.5-2, and most preferably 1.95. In the embodiment of the present invention, the pH value of the electrophoresis wastewater is controlled to change the charged properties of the organic matter in the electrophoresis wastewater, thereby adjusting the effect of the electrochemical treatment of the electrophoresis wastewater. If the pH is low, the organic matter in the electrophoresis wastewater will be positively charged, and the organic matter will be more likely to be electrophoretically deposited on the cathode. If the pH is high, on the one hand, the electrophoresis wastewater will undergo an acid-base neutralization reaction, and a portion of the organic matter will precipitate, thereby stratifying the electrophoresis wastewater, the upper layer of the solution is the supernatant, and the bottom of the solution is paint mud, which can remove some organic matter; on the other hand, some organic matter in the electrophoresis wastewater will change from positive charge to negative charge under alkaline conditions, so under the action of direct current, the organic matter in the supernatant will undergo electrophoretic deposition on the anode and cathode, and the negatively charged organic matter will be deposited on the anode, and the positively charged organic matter will be deposited on the cathode, and a portion of the organic matter will undergo electrochemical oxidation reaction at the anode. Although the method of the embodiment of the present invention can effectively remove organic matter in electrophoresis wastewater in an acidic or alkaline environment, the energy consumption is higher in an alkaline environment. Therefore, in the embodiment of the present invention, it is preferred to perform electrochemical treatment in an acidic environment.

[0026] In some embodiments, the material of the anode plate in the electrochemical reactor includes at least one of ruthenium iridium titanium, platinum titanium, iridium tantalum titanium, diamond, 316L stainless steel, and titanium plate. Preferably, the material of the anode plate in the electrochemical reactor includes at least one of ruthenium iridium titanium, platinum titanium, iridium tantalum titanium, and diamond, and more preferably diamond. In the embodiments of the present invention, preferred materials such as ruthenium iridium titanium, platinum titanium, iridium tantalum titanium, and diamond are used as the anode plate. Figure 1 As shown, part of the organic matter can also undergo electrochemical oxidation reaction on the anode to decompose the organic matter, further improving the removal rate of the organic matter, and maintaining low energy consumption while improving the removal rate of the organic matter.

[0027] In some embodiments, preferably, the material of the cathode plate in the electrochemical reactor includes at least one of 316L stainless steel, nickel foam, titanium mesh, and titanium plate, and 316L stainless steel is further preferred. In the embodiment of the present invention, the preferred material is used as the cathode plate, which is conducive to the electrophoretic deposition of positively charged substances in the electrophoretic wastewater on the cathode, thereby removing pollutants. The cathode after electrophoretic deposition can be cleaned by reversing the pole, scraping the residue, etc. In the method of the embodiment of the present invention, the preferred material is used as the cathode plate, which can maintain low energy consumption while improving the organic matter deposition effect, and the cathode material is easy to clean and reuse.

[0028] In some embodiments, in the electrochemical reactor, the spacing between the cathode and the anode is 3-10 mm, preferably 3-5 mm. In the embodiment of the present invention, the spacing between the cathode and the anode is preferably selected, which can improve the effect of electrophoretic deposition and electrochemical oxidation treatment of electrophoretic wastewater and reduce energy consumption. If the distance between the plates is small, the current efficiency is usually high, which can shorten the diffusion distance of oxidants such as hydroxyl radicals OH generated by the plates, react with organic pollutants in the electrophoretic wastewater more quickly, accelerate the mass transfer rate, facilitate the reaction, shorten the reaction time, and increase the removal rate. At the same time, the migration rate of electrons will also be accelerated due to the reduction of the distance between the plates, which helps to reduce power consumption when achieving the same treatment effect, but the distance between the plates cannot be too small, and the electrode surface is easily passivated, resulting in increased energy consumption, reduced electrolysis efficiency, and may cause problems such as short circuits. When the distance between the plates increases, the current efficiency will decrease and the processing time will be extended. This is because the increase in the distance between the plates will increase the cell voltage, thereby increasing the power consumption. In addition, the increase in the distance between the plates will also increase the diffusion distance of the generated oxidants such as hydroxyl radicals OH, resulting in a decrease in the oxidation rate. If the distance between the plates is too large, the resistance between the electrodes increases, the voltage rises, and the energy consumption also increases. In the embodiment of the present invention, the distance between the cathode and the anode is controlled within a suitable range, which effectively reduces the energy consumption while improving the organic matter removal rate.

[0029] In some embodiments, the voltage of the electrochemical treatment is 15-80V, preferably 20-40V. In the embodiment of the present invention, the voltage of the electrochemical treatment is preferably selected, which is conducive to the electrophoretic deposition of positively charged substances at the cathode. If the voltage is too high, it may exceed the limiting current density of the electrode and affect the life of the electrode. Although the voltage is too high and the reaction time is greatly shortened, it not only does not effectively improve the electrochemical treatment effect, but also increases unnecessary energy consumption; if the voltage is too low, it cannot provide sufficient driving force for electrophoretic deposition and electrochemical oxidation, resulting in poor effect of the electrochemical treatment.

[0030] In some embodiments, the voltage of the electrochemical treatment is a DC constant voltage.

[0031] In some embodiments, a magnetic stirrer is used in the electrochemical reactor for magnetic stirring; preferably, the stirring speed is 600-1000 rpm.

[0032] In some embodiments, the temperature of the electrochemical treatment is 10-30°C, and the time of the electrochemical treatment is 30-165 minutes. The method of the embodiment of the present invention can be carried out at room temperature and is easy to apply. The electrochemical treatment time in the embodiment of the present invention is also the residence time of the electrophoresis wastewater in the electrochemical reactor, which is determined according to the removal of organic matter in the electrophoresis wastewater. When the organic matter removal rate no longer increases significantly, the electrochemical treatment is terminated.

[0033] The present invention is described in detail below with reference to embodiments.

[0034] Example 1

[0035] The electrophoresis wastewater from a certain automobile workshop was pretreated. The pH value of the electrophoresis wastewater was 5.25 and the COD cr It is 9600mg / L.

[0036] 600mL of electrophoresis wastewater was adjusted to a pH value of 4.00 with dilute hydrochloric acid, and then the electrophoresis wastewater was introduced into the electrochemical reactor, and the anode and cathode plates were inserted into the plate slots in the electrochemical reactor. 316L stainless steel was used as the cathode plate, BDD (diamond) was used as the anode plate, and the electrode spacing was set to 3mm. A magnetic stirring bar was used for magnetic stirring, and the stirring speed was 600rpm. The DC regulated power supply was adjusted to the constant voltage mode, and the voltage was 20V for electrochemical treatment. The positively charged organic matter in the electrophoresis wastewater underwent a reduction reaction on the cathode, and electrophoresis was deposited on the cathode. Some organic matter underwent an electrochemical oxidation reaction on the anode to achieve the removal of organic matter. The residence time of the electrophoresis wastewater in the electrochemical reactor was 120min, and the reaction temperature was room temperature.

[0037] The electrophoresis wastewater COD after treatment in this example Cr The removal rate is 78.8% and the energy consumption is 46.6 kWh / g.

[0038] Example 2

[0039] The wastewater and pretreatment method used are the same as those in Example 1, except that the pH value of the electrophoresis wastewater is not adjusted, and the electrophoresis wastewater with a pH value of 5.25 is directly sent to the electrochemical reactor for electrochemical treatment, and the residence time of the electrophoresis wastewater in the electrochemical reactor is 150 minutes.

[0040] The electrophoresis wastewater COD after treatment in this example Cr The removal rate is 73.9% and the energy consumption is 42.8 kWh / g.

[0041] Example 3

[0042] The wastewater and pretreatment method used in Example 1 are the same, except that the pH value of the electrophoresis wastewater is adjusted to 1.95, and the residence time of the electrophoresis wastewater in the electrochemical reactor is 50 minutes.

[0043] The electrophoresis wastewater COD after treatment in this example Cr The removal rate is 85.4% and the energy consumption is 32.6kWh / g.

[0044] Example 4

[0045] The wastewater and pretreatment method used in Example 1 are the same, except that the pH value of the electrophoresis wastewater is adjusted to 8.04, and the residence time of the electrophoresis wastewater in the electrochemical reactor is 120 minutes.

[0046] The electrophoresis wastewater COD after treatment in this example Cr The removal rate was 86.0% and the energy consumption was 73.4 kWh / g.

[0047] Example 5

[0048] The wastewater and pretreatment method used in Example 1 are the same, except that the voltage value of the electrochemical treatment is 40V, and the residence time of the electrophoresis wastewater in the electrochemical reactor is 40min.

[0049] The electrophoresis wastewater COD after treatment in this example Cr The removal efficiency is 68.6% and the energy consumption is 38.5 kWh / g.

[0050] Example 6

[0051] The wastewater and pretreatment method used in Example 1 are the same, except that the voltage value of the electrochemical treatment is 60V, and the residence time of the electrophoresis wastewater in the electrochemical reactor is 30min.

[0052] The electrophoresis wastewater COD after treatment in this example CrThe removal rate is 62.4% and the energy consumption is 35.9 kWh / g.

[0053] Example 7

[0054] The wastewater and pretreatment method used are the same as those in Example 1, except that ruthenium, iridium and titanium are used as the anode.

[0055] The electrophoresis wastewater COD after treatment in this example Cr The removal efficiency is 63.8% and the energy consumption is 50.2 kWh / g.

[0056] Example 8

[0057] The wastewater and pretreatment method used in Example 1 are the same, except that a titanium mesh is used as the cathode.

[0058] The electrophoresis wastewater COD after treatment in this example Cr The removal efficiency is 71.2% and the energy consumption is 55.5kWh / g.

[0059] Example 9

[0060] The wastewater and pretreatment method used in Example 1 are the same, except that 316L stainless steel is used as the anode.

[0061] The electrophoresis wastewater COD after treatment in this example Cr The removal rate is 60.1% and the energy consumption is 47.2kWh / g.

[0062] Example 10

[0063] The wastewater and pretreatment method used in Example 1 are the same, except that the distance between the cathode and the anode is 5 mm, and the residence time of the electrophoresis wastewater in the electrochemical reactor is 135 min.

[0064] The electrophoresis wastewater COD after treatment in this example Cr The removal rate is 81.1% and the energy consumption is 66.4 kWh / g.

[0065] Embodiment 11

[0066] The wastewater and pretreatment method used in Example 1 are the same, except that the distance between the cathode and the anode is 7.5 mm, and the residence time of the electrophoresis wastewater in the electrochemical reactor is 165 min.

[0067] The electrophoresis wastewater COD after treatment in this example Cr The removal efficiency is 82.5% and the energy consumption is 83.0 kWh / g.

[0068] Example 12

[0069] The wastewater and pretreatment method used in Example 1 are the same, except that the distance between the cathode and the anode is 10 mm, and the residence time of the electrophoresis wastewater in the electrochemical reactor is 165 min.

[0070] The electrophoresis wastewater COD after treatment in this example Cr The removal rate is 82.0% and the energy consumption is 76.5 kWh / g.

[0071] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0072] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for pretreating electrophoresis wastewater, characterized in that: The electrophoresis wastewater is electrochemically treated in an electrochemical reactor to obtain treated electrophoresis wastewater.

2. The pretreatment method for electrophoresis wastewater according to claim 1, characterized in that: The pH value of the electrophoresis wastewater is adjusted to 1.5-9 before the electrochemical treatment.

3. The pretreatment method for electrophoresis wastewater according to claim 1, characterized in that: The material of the anode plate in the electrochemical reactor includes at least one of ruthenium-iridium-titanium, platinum-titanium, iridium-tantalum-titanium, diamond, 316L stainless steel, and titanium plate.

4. The pretreatment method for electrophoresis wastewater according to claim 1, characterized in that: The material of the cathode plate in the electrochemical reactor includes at least one of 316L stainless steel, nickel foam, titanium mesh and titanium plate.

5. The method for pretreating electrophoresis wastewater according to claim 1, characterized in that: The material of the anode plate in the electrochemical reactor is diamond, and the material of the cathode plate is 316L stainless steel.

6. The method for pretreating electrophoresis wastewater according to claim 1, characterized in that: In the electrochemical reactor, the distance between the cathode and the anode is 3-10 mm.

7. The method for pretreating electrophoresis wastewater according to claim 1, characterized in that: The voltage of the electrochemical treatment is 15-80V, preferably 20-40V.

8. The method for pretreating electrophoresis wastewater according to claim 1, characterized in that: The voltage of the electrochemical treatment is a DC constant voltage.

9. The method for pretreating electrophoresis wastewater according to claim 1, characterized in that: The electrochemical reactor is subjected to magnetic stirring using a magnetic stirrer, and the stirring speed is 600-1000 rpm.

10. The method for pretreating electrophoresis wastewater according to claim 1, characterized in that: The temperature of the electrochemical treatment is 10-30° C., and the time of the electrochemical treatment is 30-165 min.

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