Electroplating wastewater treatment system

Abstract

The invention relates to an electroplating wastewater treatment system. The system is sequentially provided with a pretreatment tank, an electrochemical tank, a flocculation tank, an adsorption tank and a clean water tank along the water flow direction, wherein a spoiler is arranged in the pretreatment tank to divide the pretreatment tank into a coarse filter tank and a pH regulating tank; the electrochemical cell comprises a cathode plate, an anode plate and an electrochemical workstation; the adsorption tank is filled with an adsorbent layer and is matched with a backwashing device; and both the anode plate and the adsorbent layer are made of modified carbon fibers. The invention provides an electroplating wastewater treatment system. A pretreatment tank is used for removing large-particle suspended matters in water and adjusting the pH value to be neutral; modified carbon fiber is adopted as an anode plate to oxidize organic pollutants difficult to degrade in water and then passes through the flocculation basin to form floccules, clear water is filtered into the adsorption basin to further adsorb and take out heavy metal ions in water, and the adsorption basin is provided with a backwashing device to wash an adsorption layer at any time. And the quality of the effluent after secondary flushing can basically reach the national discharge standard.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly to a system for treating electroplating wastewater. Background Art

[0002] Industrial wastewater often has complex components, containing a large number of refractory organic substances, heavy metals with biological toxicity, etc. Electroplating wastewater often contains a large number of heavy metal ions and is doped with a large amount of refractory organic additives, with many impurities. It is very difficult to meet the national discharge standards by a single treatment method. It is very necessary to design a system device for step-by-step treatment of electroplating wastewater with multiple modules, and the selection of appropriate chemical reagents in these treatment devices will also have a great impact on the water treatment results. Summary of the Invention

[0003] Aiming at the deficiencies in the prior art, the present invention proposes a complete water treatment system based on modified carbon fiber, which has obvious effects on the treatment of electroplating wastewater.

[0004] To achieve the above object, the present invention provides the following technical solutions: A system for treating electroplating wastewater, which is sequentially provided with a pretreatment tank, an electrochemical cell, a flocculation tank, an adsorption tank, and a clear water tank along the water flow direction; Wherein, a turbulence baffle is arranged in the pretreatment tank to divide it into a coarse filtration tank and a pH adjustment tank; The electrochemical cell includes a cathode plate, an anode plate, and an electrochemical workstation; The adsorption tank is filled with an adsorbent layer; Both the anode plate and the adsorbent layer use modified carbon fiber, and its preparation method is as follows: S1. Prepare a modified polyacrylonitrile spinning solution First, use 2-(4-aminophenyl)-5-aminobenzimidazole as a raw material to react with acryloyl chloride to obtain a cross-linked monomer; then add acrylonitrile, acrylamide, methyl acrylate, and AIBN to a reaction vessel, add the solvent dimethyl sulfoxide and stir to make them mix evenly, fill with nitrogen to exclude oxygen, raise the temperature for reaction, and then add the cross-linked monomer thereto and keep the temperature for reaction; S2. Make the modified polyacrylonitrile spinning solution into modified polyacrylonitrile raw filaments through a spinning process; S3. Perform pre-oxidation and carbonization treatments to prepare modified polyacrylonitrile carbon fiber; S4. Activate the modified polyacrylonitrile carbon fiber in an aqueous potassium hydroxide solution and a nitric acid solution respectively; S5. Prepare the finished product Prepare Tris buffer solution, add the dried activated carbon fiber and dopamine hydrochloride, and continuously oscillate at room temperature for 5 - 8 h, then wash with water and dry; add deionized water, thiourea, ammonia water and ZnCl₂·H₂O into the reaction kettle, stir evenly, add the dried carbon fiber and carry out hydrothermal reaction for 3 - 8 h, take out, ultrasonically clean and dry to obtain.

[0005] Further, a mechanical stirring paddle is arranged in the rough filter tank, and a first outlet is opened at the bottom of the rough filter tank; a filter screen is arranged between the spoiler plates, and the filter screen can be removed and replaced.

[0006] Further, the pH adjustment tank is equipped with a pH control device; the pH control device includes an acid-base feeding pipe and a pH probe.

[0007] Further, a power lift pump is arranged between the pretreatment tank and the electrochemical cell; the pretreatment tank, the flocculation tank and the adsorption tank are all connected to the sludge tank.

[0008] Further, the water outlet end of the electrochemical cell is connected to the bottom of the flocculation tank; a feeding port is opened at the top of the flocculation tank, and a sludge inclined plate is arranged at the bottom; a stirring rod is arranged above the sludge inclined plate; a second outlet is opened on one side of the sludge flow direction of the sludge inclined plate.

[0009] Further, a plurality of groups of filter screen plates are arranged at intervals from top to bottom in the adsorption tank, and an adsorbent layer is formed by carrying an adsorbent on the filter screen plates; the adsorbent includes the modified carbon fiber and activated carbon with a mixing ratio of ~:~, and the proportion of the modified carbon fiber increases step by step from top to bottom.

[0010] Further, an aeration pipeline is arranged below each adsorbent layer in the adsorption tank; the aeration pipeline is externally connected to a backwashing device.

[0011] Further, in step S1, the molar ratio of acrylonitrile, acrylamide, methyl acrylate, AIBN and the crosslinking monomer is 200:30 - 60:20 - 50:0.1 - 0.5:10 - 20; the reaction temperature is 70 °C, and the reaction time is to react for 3 - 6 h first and then keep warm for 2 h.

[0012] Further, in step S5, the pH of the Tris buffer solution is 9, the concentration is 10 mmol / L, and the mass ratio of the activated carbon fiber, dopamine hydrochloride, thiourea, ammonia water and ZnCl₂·H₂O is 1:0.2 - 0.5:0.5:0.2:0.6 - 0.8.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides an electroplating wastewater treatment system, which includes a pretreatment tank, an electrochemical cell, a flocculation tank, an adsorption tank, and a clear water tank; the pretreatment tank removes large particulate suspensions in the water and adjusts the pH to neutral; in the electrochemical cell, a modified carbon fiber is used as the anode plate to oxidize the refractory organic pollutants in the water body, and then flocs are formed after passing through the flocculation tank. The clear water is filtered into the adsorption tank to further adsorb and remove heavy metal ions in the water. The adsorption tank is equipped with a backwashing device to wash the adsorption layer at any time. If the effluent fails to meet the discharge standard, it will be re-introduced into the electrochemical cell for treatment in sequence. The water quality of the effluent after secondary washing can basically meet the national discharge standard. Description of the Drawings

[0014] [[ID=�]] Figure 1 It is a schematic structural diagram of an electroplating wastewater treatment system provided by this application.

[0015] In the figure: 100, pretreatment tank; 200, electrochemical cell; 300, flocculation tank; 400, adsorption tank; 500, clear water tank; 110, turbulence plate; 120, coarse filter tank; 130, pH adjustment tank; 210, anode plate; 220, cathode plate; 230, electrochemical workstation; 410, adsorbent layer; 420, aeration pipeline; 430, backwashing device; 140, stirring paddle; 150, first outlet; 160, filter screen; 170, pH control device; 171, acid-base feeding pipe; 172, pH probe; 600, power lift pump; 700, sludge tank. Specific Embodiments

[0016] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0017] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0018] Embodiment 1: An electroplating wastewater treatment system, which is sequentially arranged along the water flow direction: a pretreatment tank 100, an electrochemical cell 200, a flocculation tank 300, an adsorption tank 400, and a clear water tank 500; Among them, a turbulence plate 110 is arranged in the pretreatment tank 100 to divide it into a coarse filter tank 120 and a pH adjustment tank 130; The electrochemical cell 200 includes an anode plate 210, a cathode plate 220, and an electrochemical workstation 230; The adsorption tank 400 is filled with an adsorbent layer 410, and the adsorption tank 400 is equipped with a backwashing device 430; both the anode plate 210 and the adsorbent layer 410 use modified carbon fiber.

[0019] In this embodiment, a mechanical stirring paddle 140 is arranged in the coarse filtration tank 120, and a first outlet 150 is opened at the bottom of the coarse filtration tank 120; a filter screen 160 is arranged between the flow disturbance plates 110, and the filter screen 160 can be removed and replaced. The wastewater passes through the pretreatment tank 100. Under the rapid stirring of the mechanical stirring paddle 140, large-particle suspended matters are separated from water and fall into the bottom of the coarse filtration tank 120 under the action of gravity after being stationary. Some fine particles are intercepted by the middle filter screen 160 when passing through the flow disturbance plates 110. The filter screen 160 can be pulled out from the upper part for flushing or replacement. The suspended matters in the sewage treated by the pretreatment tank 100 are greatly reduced, improving the efficiency for subsequent electrochemical treatment and the like.

[0020] In this embodiment, the pH adjustment tank 130 is equipped with a pH control device 170; the pH control device 170 includes an acid-base feeding pipe 171 and a pH probe 172. The pH value of the water body is monitored at all times to make the pH value between 6 and 7.

[0021] In this embodiment, a power lift pump 600 is arranged between the pretreatment tank 100 and the electrochemical cell 200; the pretreatment tank 100, the flocculation tank 300 and the adsorption tank 400 are all connected to the sludge tank 700.

[0022] In this embodiment, the water outlet end of the electrochemical cell 200 is connected to the bottom of the flocculation tank 300; a feeding port 310 is opened at the top of the flocculation tank 300, and a sludge inclined plate 320 is arranged at the bottom; a stirring rod 330 is arranged above the sludge inclined plate 320; a second outlet 340 is opened on one side of the sludge inclined plate 320 in the sludge flow direction. After passing through the electrochemical cell 200, the refractory organic pollutants in the water body are oxidized. A flocculant is put into the flocculation tank 300 through the feeding port 310, so that the oxides form flocs and are discharged into the sludge tank 700 through the second outlet 340 under the action of the sludge inclined plate 320.

[0023] In this embodiment, multiple groups of filter plates are arranged at intervals from top to bottom in the adsorption tank 400, and the filter plates carry an adsorbent to form the adsorbent layer 410; the adsorbent includes the modified carbon fiber and activated carbon with a mixing ratio of 0:10 to 9:1, and the proportion of the modified carbon fiber increases step by step from top to bottom.

[0024] In this embodiment, an aeration pipeline 420 is arranged below each adsorbent layer 410 in the adsorption tank 400; the aeration pipeline 420 is externally connected to the backwashing device 430.

[0025] In this embodiment, the preparation method of the modified carbon fiber is as follows: S1. Prepare crosslinking monomers: Add 2-(4-aminophenyl)-5-aminobenzimidazole and dichloromethane into a reaction flask, place the reaction flask in an ice-water bath, add triethylamine, place acryloyl chloride in a constant-pressure dropping funnel, and dropwise add it into the reaction flask. After the dropping is completed, react at a low temperature for 1 h, and then take out the reaction flask and continue to react at room temperature to remove the solvent, thus obtaining the product; S2. Prepare a modified polyacrylonitrile spinning solution Add 2 mol of acrylonitrile, 0.3 mol of acrylamide, 0.2 mol of methyl acrylate, and 0.01 mol of AIBN into a reaction vessel, add the solvent dimethyl sulfoxide and stir to mix them evenly. Purge with nitrogen to remove oxygen, heat up to 70 °C and react for 4 h, and then add 0.1 mol of crosslinking monomers thereto and keep the temperature for reaction for 2 h.

[0026] S3. Make the modified polyacrylonitrile spinning solution into modified polyacrylonitrile precursor filaments through a spinning process, with a spinning voltage of 8 kv, a receiving distance of 12 cm, a temperature of 25 °C, and a rotation speed of 50 rpm.

[0027] S4. Prepare carbon fibers Perform pre-oxidation treatment on the modified polyacrylonitrile precursor filaments (maintain at 200 °C for 80 min in an air atmosphere), and then in an inert gas, heat up to 600-800 °C at a rate of 5 °C / min and maintain for 5-10 min; the high-temperature carbonization conditions are: heat up to 1000-1200 °C at a rate of 5 °C / min and maintain for 1-5 min to obtain modified polyacrylonitrile carbon fibers; S5. Activate carbon fibers Immerse the modified polyacrylonitrile carbon fibers in a 5 mol / L aqueous potassium hydroxide solution and carry out a hydrothermal reaction for 2 h, and then soak them in a 1 mol / L nitric acid solution for 2 h. Take them out, wash with water until neutral, and dry; S6. Prepare the finished product Prepare a Tris buffer solution (pH = 9, concentration of 10 mmol / L), add 5 g of the dried activated carbon fibers and 1 g of dopamine hydrochloride, continuously oscillate at room temperature for 5-8 h, wash with water and dry; add 100 ml of deionized water, 2.5 g of thiourea, 1 g of ammonia water, and 3 g of ZnCl2·H2O into a reaction kettle, stir evenly, add the dried carbon fibers and carry out a hydrothermal reaction for 3-8 h, take them out, ultrasonically clean and dry to obtain the product.

[0028] The carbon yield is 47.9%, the fiber diameter is 2.4 μm, and the tensile strength is 4025 MPa.

[0029] Application example: The water quality of the electroplating wastewater in a certain electroplating factory is as follows: Cr 2+ : 1.21 mg / L, Zn 2+ : 153 mg / L, Cu 2+ : 61.3 mg / L, Ni 2+ : 65.4 mg / L, COD: 358 mg / L.

[0030] Pass the wastewater through the above electroplating wastewater treatment system. First, it enters the pretreatment tank 100. Under the action of the mechanical stirring paddle 140, large particle suspensions are separated. Small particle suspensions are intercepted by the filter screen 160 when passing through the spoiler 110. The pretreated wastewater enters the electrochemical cell 200. The modified carbon fiber is made into the anode plate 210, and the graphite felt is used as the cathode plate 220 to degrade organic matter. Add flocculants into the flocculation tank 300 to remove organic matter. Then it is introduced into the adsorption tank 400. Through step-by-step filtration, heavy metal ions in the water are adsorbed. The treated clear water flows back to the electrochemical cell 200 for secondary treatment. The water quality of the final effluent is as follows: Cr 2+ : 0.01 mg / L, Zn 2+ : 0.3 mg / L, Cu 2+ : 0.2 mg / L, Ni 2+ : 0.4 mg / L, COD: 13.2, meeting the discharge standard of GB21900-2008.

[0031] Although the embodiments of the present invention have been disclosed as above, it is not limited to only the applications listed in the description and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details.

Claims

1. An electroplating wastewater treatment system, characterized in that, The system is sequentially provided with: a pretreatment tank (100), an electrochemical cell (200), a flocculation tank (300), an adsorption tank (400), and a clear water tank (500) along the water flow direction; Among them, a turbulence plate (110) is arranged in the pretreatment tank (100) to divide it into a coarse filtration tank (120) and a pH adjustment tank (130); The electrochemical cell (200) includes an anode plate (210), a cathode plate (220), and an electrochemical workstation (230); An adsorbent layer (410) is filled in the adsorption tank (400); Both the anode plate (210) and the adsorbent layer (410) use modified carbon fiber, and its preparation method is as follows: S1. Prepare a modified polyacrylonitrile spinning solution First, use 2-(4-aminophenyl)-5-aminobenzimidazole as a raw material to react with acryloyl chloride to obtain a cross-linked monomer; then add acrylonitrile, acrylamide, methyl acrylate, and AIBN to a reaction vessel, add the solvent dimethyl sulfoxide and stir to mix evenly, purge with nitrogen to remove oxygen, raise the temperature for reaction, and then add the cross-linked monomer thereto and keep the temperature for reaction; S2. Make the modified polyacrylonitrile spinning solution into modified polyacrylonitrile raw filaments through a spinning process; S3. Prepare modified polyacrylonitrile carbon fiber through pre-oxidation and carbonization treatment; S4. Activate the modified polyacrylonitrile carbon fiber in an aqueous potassium hydroxide solution and a nitric acid solution respectively; S5. Prepare the finished product Prepare Tris buffer solution, add the dried activated carbon fiber and hydrochloric acid dopamine, continuously oscillate at room temperature for 5-8 h, wash with water and dry; add deionized water, thiourea, ammonia water, and ZnCl2·H2O to a reaction kettle, stir evenly, add the dried carbon fiber and carry out a hydrothermal reaction for 3-8 h, take it out, ultrasonically clean and dry to obtain.

2. The electroplating wastewater treatment system according to claim 1, characterized in that, A mechanical stirring paddle (140) is arranged in the coarse filtration tank (120), and a first outlet (150) is opened at the bottom of the coarse filtration tank (120); a filter screen (160) is arranged between the turbulence plates (110), and the filter screen (160) can be removed and replaced.

3. The electroplating wastewater treatment system according to claim 1, wherein The pH adjustment tank (130) is equipped with a pH control device (170); the pH control device (170) includes an acid-base feeding pipe (171) and a pH probe (172).

4. The electroplating wastewater treatment system according to claim 1, characterized in that, A power lift pump (600) is arranged between the pretreatment tank (100) and the electrochemical cell (200); the pretreatment tank (100), the flocculation tank (300), and the adsorption tank (400) are all connected to a sludge tank (700).

5. The electroplating wastewater treatment system according to claim 1, wherein, The water outlet end of the electrochemical cell (200) is connected to the bottom of the flocculation tank (300); a feeding port (310) is opened at the top of the flocculation tank (300), and a sludge inclined plate (320) is arranged at the bottom; a stirring rod (330) is arranged above the sludge inclined plate (320); a second outlet (340) is opened on one side of the sludge inclined plate (320) in the sludge flow direction.

6. The electroplating wastewater treatment system according to claim 1, wherein In the adsorption tank (400), a plurality of filter plates are arranged at intervals from top to bottom, and an adsorbent layer (410) is formed by carrying an adsorbent on the filter plates; the adsorbent includes the modified carbon fiber and activated carbon with a mixing ratio of 0:10 to 9:1, and the proportion of the modified carbon fiber increases step by step from top to bottom.

7. The electroplating wastewater treatment system according to claim 1, characterized in that, In the adsorption tank (400), an aeration pipe (420) is arranged below each adsorbent layer (410); the aeration pipe (420) is externally connected to a backwashing device (430).

8. The electroplating wastewater treatment system according to claim 1, wherein, In the step S1, the molar ratio of acrylonitrile, acrylamide, methyl acrylate, AIBN and the crosslinking monomer is 200:30 to 60:20 to 50:0.1 to 0.5:10 to 20; the reaction temperature is 70 °C, and the reaction time is to react for 3 to 6 h first and then keep warm for 2 h.

9. The electroplating wastewater treatment system according to claim 1, wherein In the step S5, the pH of the Tris buffer solution is 9, the concentration is 10 mmol / L, and the mass ratio of the activated carbon fiber, hydrochloric acid dopamine, thiourea, ammonia water and ZnCl2·H2O is 1:0.2 to 0.5:0.5:0.2:0.6 to 0.8.

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