Method for treating battery soaking discharge wastewater

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a method for treating battery soaking discharge wastewater. The treatment method comprises the following steps: pretreating the battery soaking discharge wastewater to remove fluorine ions, sulfate radicals and phosphate radicals; the method is characterized in that pretreated wastewater formed by pretreatment is subjected to two-stage micro-electro-oxygen electro-catalytic oxidation, and conditions of each stage of micro-electro-oxygen electro-catalytic oxidation include that a catalyst is activated carbon loaded with Re-Ti bimetal, 1-6 g of electrolyte salt is correspondingly added to each liter of the pretreated wastewater, and the pH value of the pretreated wastewater is 2.5-3.5. According to the treatment method, phosphorus-containing substances such as COD (Chemical Oxygen Demand), fluorine, inorganic phosphorus, organophosphorus and organophosphorus-like substances in the battery soaking discharge wastewater can be efficiently removed at the same time, and the treatment cost of the battery soaking discharge wastewater is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a battery soaking and discharging wastewater treatment method. BACKGROUND

[0002] New energy vehicle power batteries are developing rapidly, and the volume of waste batteries that are scrapped and retired is increasing explosively. Battery recycling is crucial to the sustainable development of social economy and environment. In the wet recovery process of waste lithium iron phosphate batteries, the waste batteries need to be discharged, disassembled, and crushed. The battery soaking and discharging wastewater generated in this process contains high-concentration organic matter (represented by COD), fluorine, and difficult-to-degrade electrolyte (lithium hexafluorophosphate, phosphorus in the form of organophosphorus), and the conventional calcium method and aluminum method cannot remove the organophosphorus in the wastewater.

[0003] Currently, common methods for removing COD include catalytic oxidation, biochemical method, extraction method, and activated carbon adsorption method, but they cannot remove organic phosphorus in wastewater at the same time. When using the adsorption method to treat wastewater, the adsorbent adsorbs a large amount of chemicals and becomes a hazardous waste after saturation, which is difficult to regenerate and use. Common methods for removing phosphorus include resin method and special removal agent, but the resin method is high in cost and needs to be regenerated and replaced regularly, and the special removal agent is not suitable for industrial mass production.

[0004] Therefore, how to efficiently remove COD, organophosphorus, and fluorine in wastewater at the same time is a problem that needs to be improved and solved at present.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of the present application is to provide a battery soaking and discharging wastewater treatment method. The treatment method provided in the present application can efficiently remove COD, fluorine, inorganic phosphorus, organic phosphorus, and organophosphorus in battery soaking and discharging wastewater at the same time, and reduce the treatment cost of battery soaking and discharging wastewater.

[0007] The present application is implemented as follows: In a first aspect, the present application provides a battery soaking and discharging wastewater treatment method, which comprises: pretreating battery soaking and discharging wastewater to remove fluorine ions, sulfate ions, and phosphate ions; The pretreated wastewater formed by pretreatment is subjected to two-stage micro-electric oxygen electrocatalytic oxidation, wherein the conditions of each stage of micro-electric oxygen electrocatalytic oxidation include: the catalyst is a Re-Ti bimetal-loaded activated carbon, 1-6 g of electrolyte salt is added per liter of the pretreated wastewater, and the pH of the pretreated wastewater is 2.5-3.5.

[0008] In an alternative embodiment, the two-stage micro-electric oxygen electro-catalytic oxidation comprises: performing first-stage micro-electric oxygen electro-catalytic oxidation on the pretreated wastewater, then adjusting the pH to 2.5-3.5, and then performing second-stage micro-electric oxygen electro-catalytic oxidation. Preferably, aeration is performed during the first-stage micro-electric oxygen electro-catalytic oxidation and the second-stage micro-electric oxygen electro-catalytic oxidation.

[0009] In an alternative embodiment, the conditions of the two-stage micro-electric oxygen electro-catalytic oxidation satisfy the following requirements: (1) The conditions of the first-stage micro-electric oxygen electro-catalytic oxidation include: a current density of 5-20 mA / cm 2 , and an electrolysis time of 3-5 h; (2) The conditions of the second-stage micro-electric oxygen electro-catalytic oxidation include: a current density of 5-20 mA / cm 2 , and an electrolysis time of 1-3 h.

[0010] In an alternative embodiment, the raw material for forming the Re-Ti bimetal-loaded activated carbon satisfies the following requirements: (1) The raw material for the activated carbon is columnar; (2) The length of the raw material for the activated carbon is 8-120 mm; (3) The specific surface area of the raw material for the activated carbon is 150-200 m² / g; (4) The porosity of the raw material for the activated carbon is 60%-70%.

[0011] In an alternative embodiment, the pretreatment comprises: mixing the battery soaking and discharging wastewater with a calcium-containing compound to remove fluoride ions, sulfate ions, and phosphate ions, and then adding a carbonate to remove calcium ions.

[0012] In an alternative embodiment, the pretreatment satisfies the following conditions: (1) The amount of the calcium-containing compound is 1.0-1.5 times the total theoretical molar amount of the sulfate ions, fluoride ions, and phosphate ions to be removed; (2) The reaction time of the battery soaking and discharging wastewater with the calcium-containing compound is 0.5-1 h; (3) The amount of the carbonate is 1.0-1.5 times the theoretical molar amount for completely removing calcium ions; (4) The reaction time with the carbonate is 0.5-1 h.

[0013] In an alternative embodiment, the calcium-containing compound comprises calcium oxide or calcium hydroxide; and the carbonate comprises sodium carbonate.

[0014] In an alternative embodiment, the battery soaking and discharging wastewater satisfies at least one of the following requirements: (1) COD 4000~5000mg / L; (2) F - 100~400mg / L; (3) TP 370~520mg / L; (4) The pH of the battery soaking discharge wastewater is 5-7.

[0015] In the optional embodiment, the regeneration of the catalyst in the micro-electric oxygen electro-catalytic oxidation is further included. Preferably, when the concentration of TP in the effluent formed after the two-stage micro-electric oxygen electro-catalytic oxidation treatment exceeds 8mg / L or the concentration of COD exceeds 500mg / L, the catalyst in the first-stage micro-electric oxygen electro-catalytic oxidation is regenerated.

[0016] In the optional embodiment, the regeneration operation includes: reversing the positive and negative electrodes, adding water, acid and electrolyte salt, and applying current. Preferably, the regeneration conditions meet any one of the following requirements: (1) 1-3g of the electrolyte salt per liter of the water, (2) 1-1.5ml of the acid per liter of the water; (3) The acid is concentrated sulfuric acid; (4) The current density is 25-35 mA / cm 2 , and the electrolysis time is 20-40min. Preferably, the method further includes: using the regenerated catalyst for the second-stage micro-electric oxygen electro-catalytic oxidation after the regeneration is completed, and the catalyst originally used in the second-stage micro-electric oxygen electro-catalytic oxidation is used in the first-stage micro-electric oxygen electro-catalytic oxidation; and returning the regeneration liquid to the pretreatment.

[0017] The present application has the following beneficial effects: (1) The embodiment of the present application can treat the battery soaking discharge wastewater to meet the third standard of the Comprehensive Sewage Discharge Standard (GB8978-1996) by combining the pretreatment for removing fluoride ions, sulfate ions and phosphate ions and the micro-electric oxygen electro-catalytic oxidation. - Compared with the traditional combined process of high-temperature acidolysis, biochemical treatment and Fenton, the treatment process is simple and the treatment efficiency is higher.

[0018] (2) The micro-electric oxygen electro-catalytic oxidation in the treatment method provided by the embodiment of the present application combines the catalyst and electrolysis, efficiently generates hydrogen peroxide, hydroxyl radicals (·OH) and other high-activity oxygen at a low current density, and is used for efficient oxidation and decomposition of organic matter. Meanwhile, the catalyst can form Re-Ti-C internal electrolysis, further removing organic matter. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0020] Figure 1 The structural schematic diagram of the micro-electric oxygen electro-catalytic oxidation device provided by the embodiments of the present application is shown in the figure. Figure 2 The XRD graph of the Re-Ti bimetallic loaded activated carbon provided by the embodiment 1 of the present application is shown in the figure.

[0021] Figure legend: 100-electrode unit; 101-anode; 102-cathode; 103-net bag; 110-catalyst unit; 120-air distribution unit; 121-aeration head; 130-hydrolysis tank. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions suggested by the manufacturers. The reagents or instruments not mentioned by the manufacturers are all conventional products that can be purchased in the market.

[0023] In a first aspect, the embodiments of the present application provide a treatment method of battery soaking discharge wastewater, comprising: S1, pretreatment; The battery soaking discharge wastewater and the calcium-containing compound are mixed to react to form calcium sulfate, calcium fluoride and calcium phosphate precipitates, so that sulfate, fluoride and phosphate are removed from the battery soaking discharge wastewater, and the reaction time is 0.5-1.0 h. The corrosion of the electrode can be reduced after the pretreatment of removing the fluoride.

[0024] The battery soaking discharge wastewater is the wastewater formed by soaking and discharging in the wet recovery process of waste lithium iron phosphate battery. The pH of the battery soaking discharge wastewater provided by the embodiments of the present application is 5-7, and the main pollutants are COD (for example, 4000-5000 mg / L), F - (for example, 100-400 mg / L), TP (for example, 370-520 mg / L).

[0025] The amount of the calcium-containing compound is 1.0-1.5 times the total theoretical molar amount of sulfate, fluoride and phosphate to be removed; for example, 1.0 times, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times or any value between 1.0-1.5 times. The calcium-containing compound includes calcium oxide or calcium hydroxide. The above conditions can ensure that the sulfate, fluoride and phosphate are completely removed.

[0026] Then, the solution after adding the calcium-containing compound is added with a complete removal of Ca 2+ The amount of the carbonate (for example, sodium carbonate) is 1.0-1.5 times the theoretical molar amount, and the reaction generates calcium carbonate precipitate to be removed from the wastewater, and the reaction time is 0.5-1.0 h, which avoids the formation of calcium scale on the catalyst and electrode in the subsequent micro-electrolysis electro-catalytic oxidation, and shortens the service life.

[0027] Finally, pressure filtration is performed to obtain the filtrate, i.e., the pretreated wastewater, and the pH of the pretreated wastewater is adjusted to 2.5-3.5, for example, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5 or any value between 2.5-3.5. Controlling the pH of the pretreated wastewater is conducive to the subsequent micro-electrolysis electro-catalytic oxidation. If the pH of the pretreated wastewater is too high or too low, the effect of the micro-electrolysis electro-catalytic oxidation may be reduced, which in turn leads to poor removal of COD or TP.

[0028] S2, micro-electrolysis electro-catalytic oxidation; The pretreated wastewater formed by the pretreatment is subjected to two-stage micro-electrolysis electro-catalytic oxidation. Specifically, the pretreated wastewater is subjected to first-stage micro-electrolysis electro-catalytic oxidation, and then the pH is adjusted to 2.5-3.5 for second-stage micro-electrolysis electro-catalytic oxidation. The micro-electrolysis electro-catalytic oxidation combines electrolysis and catalysis to efficiently remove organic matter.

[0029] Specifically, the pretreated wastewater with a pH of 2.5-3.5 is poured into a first-stage micro-electrolysis electro-catalytic oxidation device, aeration is turned on, electrolyte salt is added, electrolysis is performed after complete dissolution by turning on the power. After electrolysis, sulfuric acid is added to adjust the pH to 2.5-3.5, and the wastewater is poured into a second-stage micro-electrolysis electro-catalytic oxidation device, aeration is turned on, electrolyte salt is added, electrolysis is performed after complete dissolution by turning on the power. The COD in the pretreated wastewater is mineralized and decomposed under the synergistic action of the various active oxygen molecules produced by anode oxidation and cathode production, and the organic phosphorus in the wastewater is adsorbed on the catalyst during electrolysis.

[0030] The electrolytic salt can be a commercially available electrolytic salt, such as one or more of sodium sulfate, sodium chloride, but is not limited thereto. The electrolytic salt is added at a concentration of 1-6 g per liter of the pretreated wastewater; for example, 1 g, 2 g, 3 g, 4 g, 5 g, 6 g, or any value between 1-6 g. The electrolytic salt facilitates the flow of ions, thereby improving the effect of the micro-electrolysis electro-catalytic oxidation and improving the effect of the decomposition of the organic matter.

[0031] The conditions for the first-stage micro-electrolysis electro-catalytic oxidation include: the current density is 5-20 mA / cm 2 , for example, 5 mA / cm 2 , 10 mA / cm 2 , 15 mA / cm 2 , 20 mA / cm 2 , or any value between 5-20 mA / cm 2 . The electrolysis time is 3-5 h, for example, 3 h, 4 h, 5 h, or any value between 3-5 h. The aeration intensity is 2.0-3.0 m 3 / (m 2 h); for example, 2 m 3 / (m 2 h), 2.5 m 3 / (m 2 h), 3 m 3 / (m 2 h), or any value between 2.0-3.0 m 3 / (m 2 h). The conditions provided by the embodiments of the present application facilitate the decomposition of COD and TP.

[0032] The conditions for the second-stage micro-electrolysis electro-catalytic oxidation include: the current density is 5-20 mA / cm 2 , for example, 5 mA / cm 2 , 10 mA / cm 2 , 15 mA / cm 2 , 20 mA / cm 2 , or any value between 5-20 mA / cm 2 . The electrolysis time is 1-3 h; for example, 1 h, 2 h, 3 h, or any value between 1-3 h. The aeration intensity is 2.0-3.0 m 3 / (m 2 h); for example, 2 m 3 / (m 2 h), 2.5 m 3 (m 2 h), 3 m 3 (m 2 h), or any value between 2.0-3.0 m 3 (m 2 h). The conditions provided by the embodiments of the present application are beneficial to the decomposition of COD and TP.

[0033] Further, the cathode reaction in the two-stage micro-electric oxygen electro-catalytic oxidation is as follows:

[0034] The anode reaction in the two-stage micro-electric oxygen electro-catalytic oxidation is as follows:

[0035] MO x represents the surface of the metal oxide anode.

[0036] MO x (·OH) represents the adsorption of hydroxyl radicals on the anode surface.

[0037] Further, the catalyst used in each stage of the micro-electric oxygen electro-catalytic oxidation is a Re-Ti bimetallic supported activated carbon, which can be purchased or prepared according to existing methods.

[0038] The embodiments of the present application provide the following examples for illustration: The cylindrical activated carbon raw material (length 8-120 mm, specific surface area 150~200 m² / g, porosity 60%~70%) is selected as the carrier, and the Re-Ti bimetallic supported activated carbon catalyst (Re-Ti bimetallic catalyst) is formed by loading composite metal oxides through impregnation-calcination method. The specific preparation steps are as follows: the cylindrical activated carbon raw material is added into the titanium sol with a concentration of 0.5 mol / L according to a solid-liquid ratio of 1:8, and stirred at 40℃ for 5 hours, so that the titanium species penetrates into the pores and is adsorbed on the surface. After standing for 2 hours, it is filtered, dried at 100℃, and then calcined at 400℃ in air atmosphere for 3 hours, so that the titanium species is converted into stable TiO2. The activated carbon loaded with titanium is added into the rhenium solution with a concentration of 1 mol / L, heated and stirred at 80℃ for 1 hour, so that ReO4 - is attached by adsorption or ion exchange. After filtration, drying at 100℃, and reduction at 500℃ in hydrogen atmosphere for 3 hours, ReO4 - is reduced to metallic rhenium (Re 0 ).

[0039] The catalyst is filled between the cathodes of the micro-electric oxygen electro-catalytic oxidation device, and the filling height is 80% of the effective height of the pool body. Due to the large specific surface area, Re-Ti can form a bimetallic stable center, improve the mass transfer efficiency, and promote the cathode to generate hydrogen peroxide, hydroxyl radicals (·OH) and other high active oxygen in situ by two-electron redox reaction at low current density for efficient oxidation and decomposition of organic matter.

[0040] Further, the micro-electric oxygen electro-catalytic oxidation device adopts a device capable of simultaneously realizing catalysis and electrolysis, for example, a device with the following structure.

[0041] Referring to Figure 1 , the micro-electric oxygen electro-catalytic oxidation device comprises an electrode unit 100, a catalyst unit 110, a gas distribution unit 120 and a hydrolysis tank 130. The electrode unit 100, the catalyst unit 110 and the gas distribution unit 120 are all arranged in the hydrolysis tank 130, and then catalysis and electrolysis are carried out in the hydrolysis tank 130. Specifically, the electrode unit 100 comprises an anode 101 and a cathode 102, both of which are arranged in the hydrolysis tank 130. The anode 101 is a niobium-based coating electrode, and the cathode 102 unit is a titanium-based coating electrode, which has good electrical conductivity and corrosion resistance. Both the cathode 102 and the anode 101 are provided with cavities to facilitate the flow of wastewater and gas; the distance between the anode 101 and the cathode 102 is 40 mm, and the area of each electrode unit 100 is 100 cm 2 .

[0042] The negative electrode is loaded into a mesh bag 103 filled with catalyst-activated carbon. Due to the large specific surface area, the mass transfer efficiency can be improved, and the cathode 102 can efficiently generate hydrogen peroxide, hydroxyl radicals (·OH) and other high active oxygen in situ by two-electron redox reaction at low current density for efficient oxidation and decomposition of organic matter. Water molecules react at the anode 101 to generate ·OH and are adsorbed on the electrode surface, making them have extremely high oxidation ability and being able to attack and mineralize almost all organic matter without selectivity. The anode 101 oxidation and the cathode 102 production of various active oxygen molecules synergistically oxidize, greatly improving the utilization rate of electrons. In addition, the built-in micro-electrolysis effect of Re, Ti and carbon improves the COD removal rate to 99%. The refractory organic phosphorus enters the catalyst channel through adsorption to achieve the purpose of preliminary removal. After two-stage micro-electric oxygen electro-catalytic oxidation, the effluent COD, F - and TP meet the third standard of the "Integrated Wastewater Discharge Standard" (GB8978-1996).

[0043] The catalyst unit 110 is the aforementioned Re-Ti bimetallic activated carbon. The Re-Ti bimetallic activated carbon is placed in the mesh bag 103.

[0044] The air distribution unit 120 is arranged at the bottom of the hydrolysis tank 130, and the air distribution unit 120 comprises an aeration pipe and an aeration head 121, the aeration head 121 is a microporous aeration disc (with a pore diameter of 10-20 μm), the aeration head 121 is in communication with the aeration pipe, and an air compressor is connected to the aeration head 121, and the aeration intensity is 2.0-3.0 m 3 / (m 2 h) The aeration not only provides oxygen for the electrocatalytic reaction, promotes the reduction of OH- generated at the cathode 102, but also stirs the wastewater, so that the Re-Ti bimetal-loaded activated carbon is in a fluidized state, agglomeration is avoided, and the mass transfer efficiency is enhanced.

[0045] S3, the catalyst is regenerated; When the TP concentration of the effluent formed after the two-stage micro-electric oxygen electrocatalytic oxidation treatment exceeds 8 mg / L or the COD concentration exceeds 500 mg / L, that is, when the TP and COD of the effluent formed after the second-stage micro-electric oxygen electrocatalytic oxidation treatment do not meet the requirements, it indicates that the catalyst in the first-stage micro-electric oxygen electrocatalytic oxidation device has been saturated and needs to be regenerated.

[0046] Specifically, the positive and negative electrodes are reversely connected, 1 L of tap water or pure water is poured, aeration is started, 1-1.5 mL of acid (for example, 98% concentrated sulfuric acid) and 1-3 g of electrolyte salt are added, the current density is adjusted to 25-35 mA / cm 2 , electrolysis is performed for 20-40 min, the impurities adhered to the material pores gradually fall off, the organic phosphorus adsorbed in the pores of the catalyst is converted into inorganic phosphorus and dissolved in water under the action of electrocatalytic oxidation, and the catalyst restores the treatment capacity. After regeneration, the regenerated catalyst is loaded into the second-stage micro-electric oxygen electrocatalytic oxidation device, and the catalyst originally in the second-stage micro-electric oxygen electrocatalytic oxidation is loaded into the first-stage micro-electric oxygen electrocatalytic oxidation device, which are alternately used and recycled. The regenerated liquid after regeneration contains pollutants such as phosphorus and SS, and is returned to S1 for removal by flocculation and sedimentation.

[0047] In the embodiment of the present application, the impurities adsorbed in the catalyst gradually fall off under the action of regeneration electrolysis by reversely connecting the positive and negative electrodes, adding acid and electrolyte salt, and the catalyst is regenerated, which can reduce the purchase cost of the catalyst and the outsourcing disposal fee. In the regeneration process, the organic phosphorus adsorbed in the pores of the catalyst is oxidized and decomposed into inorganic phosphorus and dissolved in water, which can be removed by the conventional calcium method. Compared with the single electrolysis device which cannot degrade and remove TP, the P-F bond in the electrolyte wastewater can be broken, and the industry problem that the traditional calcium method and aluminum method cannot effectively remove phosphorus in the electrolyte wastewater is overcome.

[0048] In summary, the immersion wastewater can be treated to meet the requirements by the two-step method of calcium addition and removal pretreatment and micro-electric oxygen electrocatalytic oxidation. - ​And TP meet "Integrated Wastewater Discharge Standard" (GB8978-1996) three standard. Compared with traditional need high temperature acidolysis, biochemical, fenton combined process, the treatment process is simple, and the treatment efficiency is higher. The features and performance of the present application are further described in detail below in conjunction with examples.

[0049] Example 1 The present application provides a kind of battery soaking discharge wastewater treatment method, comprising: S1, pretreatment; To battery soaking discharge wastewater (pH=5.5) 1.3 times of calcium hydroxide that completely removes PO4 3- , SO4 2- And F - Theoretical value is added, and PO4 3- , SO4 2- , F - In battery soaking discharge wastewater reacts to generate calcium phosphate, calcium sulfate and calcium fluoride precipitate, and the reaction time is 0.8h.

[0050] Then, 1.2 times of sodium carbonate that completely removes Ca 2+ Theoretical value is added to the solution after adding calcium compound, and Ca 2+ In wastewater reacts to generate calcium carbonate precipitate, and the reaction time is 0.7h, and filtration.

[0051] S2, micro-electric oxygen electrocatalytic oxidation; Cylindrical activated carbon is added to titanium sol with a concentration of 0.5 mol / L according to a solid-liquid ratio of 1:8, stirred at 40 DEG C for 5 hours, so that titanium species penetrates into pores and is adsorbed on the surface. After standing for 2 hours, filtration is carried out, and then drying is carried out at 100 DEG C, and then calcination is carried out at 400 DEG C for 3 hours in an air atmosphere, so that the titanium species is converted into stable TiO2. The activated carbon loaded with titanium is added to a rhenium solution with a concentration of 1 mol / L, heated and stirred at 80 DEG C for 1 hour, so that ReO4 - is attached by adsorption or ion exchange. Filtration is carried out, drying is carried out at 100 DEG C, and then reduction is carried out at 500 DEG C for 3 hours in a hydrogen atmosphere, so that ReO4 - is reduced to metallic rhenium (Re 0 ). The catalyst of activated carbon loaded with Re-Ti bimetal is prepared. The catalyst filler is filled between cathodes, and the filling height is 80% of the effective height of the pool body. The XRD pattern of the activated carbon loaded with Re-Ti bimetal is shown in Figure 2 .

[0052] Sulfuric acid is added to the filtrate formed in S1 to adjust the pH to 3, 1L of the filtrate with adjusted pH is measured, poured into the first micro-electric oxygen electrocatalytic oxidation device, 300g of activated carbon loaded with Re-Ti bimetal is loaded in the negative electrode net bag, aeration is started, and the aeration intensity is 2.5 m 3(m 2 h); adjust the current density to 10 mA / cm 2， Electrolysis time 4h. After the first electrolysis, pour into the second micro-electric oxygen electro-catalytic oxidation device, add sulfuric acid to adjust the pH of the wastewater to 3, load 300g of Re-Ti bimetal loaded activated carbon into the negative electrode net bag, open the aeration, and the aeration intensity is 2.5 m 3 (m 2 h); adjust the current density to 10 mA / cm 2 , electrolysis time 1h. The test results are shown in Table 1.

[0053] Table 1 Test results

[0054] Example 2 The embodiment of the application provides a battery soaking discharge wastewater treatment method, comprising: S1, pretreatment; Add 1.5 times of calcium hydroxide to the battery soaking wastewater (pH=6.2) to completely remove PO4 3- , SO4 2- and F - , and react with PO4 3- , SO4 2- and F - in the wastewater to generate calcium phosphate, calcium sulfate and calcium fluoride precipitates, and the reaction time is 1.0h.

[0055] Then, 1.5 times of sodium carbonate to completely remove Ca 2+ theoretical value is added to the solution after adding the calcium compound, and reacts with Ca 2+ in the wastewater to generate calcium carbonate precipitate, and the reaction time is 1.0h, and filtration.

[0056] S2, micro-electric oxygen electro-catalytic oxidation; Add sulfuric acid to the filtrate formed in S1 to adjust the pH to 2.5, measure 1L of the filtrate with adjusted pH, pour into the first micro-electric oxygen electro-catalytic oxidation device, load 300g of Re-Ti bimetal loaded activated carbon into the negative electrode net bag, open the aeration, and the aeration intensity is 2 m 3 (m 2 h); add 6g of sodium sulfate, and adjust the current density to 20 mA / cm 2 , electrolysis time 3h. After the first electrolysis, pour into the second micro-electric oxygen electro-catalytic oxidation device, add sulfuric acid to adjust the pH of the wastewater to 2.5, load 300g of Re-Ti bimetal loaded activated carbon into the negative electrode net bag, open the aeration, and the aeration intensity is 2 m3 / (m 2 h); Adjust the current density to 20 mA / cm² 2 The electrolysis time was 3 hours. The test results are shown in Table 2.

[0057] Table 2 Test Results

[0058] Example 3 This invention provides a method for treating battery immersion discharge wastewater, comprising: S1, Preprocessing; Add PO4-free solvent to the battery soaking wastewater (pH=6.8). 3- SO4 2- and F - 1.0 times the theoretical value of calcium hydroxide, with P PO4 in the wastewater 3- SO4 2- and F - The reaction produces calcium phosphate, calcium sulfate, and calcium fluoride precipitates, and the reaction time is 0.5 h.

[0059] Next, calcium-containing compounds were added to the solution to completely remove the calcium. 2+ Sodium carbonate at 1.0 times the theoretical value, reacting with Ca in the wastewater. 2+ The reaction produces calcium carbonate precipitate, and the reaction time is 1.5 hours. The mixture is then filtered.

[0060] S2, micro-electro-oxidative oxygenation; Add sulfuric acid to the filtrate formed in S1 to adjust the pH to 3.5. Measure 1L of the pH-adjusted filtrate and pour it into the first-stage micro-electro-catalytic oxidation device. Place 300g of Re-Ti bimetallic loaded activated carbon in the negative electrode mesh bag, turn on aeration, and set the aeration intensity to 3m. 3 / (m 2 h); Add 1g of sodium sulfate and adjust the current density to 5mA / cm. 2 Electrolysis time: 5 hours. After the first stage of electrolysis, the wastewater is poured into the second stage micro-electro-oxygen electrocatalytic oxidation device. Sulfuric acid is added to adjust the pH of the wastewater to 3.5. 300g of Re-Ti bimetallic loaded activated carbon is placed in the negative electrode mesh bag. Aeration is turned on, with an aeration intensity of 3 m³ / h. 3 / (m 2 h); Adjust the current density to 5 mA / cm² 2 The electrolysis time was 2 hours. The test results are shown in Table 3.

[0061] Table 3 Test Results

[0062] Comparative Example 1 This comparative example provides a treatment method of battery soaking discharge wastewater, which has the same operation as the treatment method provided in Example 1, and the only difference is that the pH is adjusted to 4.2 with sulfuric acid, and the remaining steps are the same as Example 1. The test results are shown in Table 4.

[0063] Table 4 Test results

[0064] Comparative Example 2 This comparative example provides a treatment method of battery soaking discharge wastewater, which has the same operation as the treatment method provided in Example 1, and the only difference is that the pH is adjusted to 1.4 with sulfuric acid, and the remaining steps are the same as Example 1. The test results are shown in Table 5.

[0065] Table 5 Test results

[0066] Comparative Example 3 This comparative example provides a treatment method of battery soaking discharge wastewater, which has the same operation as the treatment method provided in Example 1, and the only difference is that the current density of the first stage and the second stage of the micro-electro-oxygen electro-catalytic oxidation is 4 mA / cm 2 , and the remaining steps are the same as Example 1. The test results are shown in Table 6.

[0067] Table 6 Test results

[0068] Comparative Example 4 This comparative example provides a treatment method of battery soaking discharge wastewater, which has the same operation as the treatment method provided in Example 1, and the only difference is that the current density of the first stage of the micro-electro-oxygen electro-catalytic oxidation is 22 mA / cm 2 , and the remaining steps are the same as Example 1. The test results are shown in Table 7.

[0069] Table 7 Test results

[0070] Comparative Example 5 This comparative example provides a treatment method of battery soaking discharge wastewater, which has the same operation as the treatment method provided in Example 1, and the only difference is that the electrolysis time of the first stage of the micro-electro-oxygen electro-catalytic oxidation is 2.5 h, and the remaining steps are the same as Example 1. The test results are shown in Table 8.

[0071] Table 8 Test results

[0072] Comparative Example 6 This comparative example provides a treatment method of battery soaking discharge wastewater, which has the same operation as the treatment method provided in Example 1, and the only difference is that the electrolytic time of the micro-electric oxygen electro-catalytic oxidation of the second section is 0.5 h, and the remaining steps are the same as Example 1. The test results are shown in Table 9.

[0073] Table 9 Test results

[0074] Comparative Example 7 This comparative example provides a treatment method of battery soaking discharge wastewater, which has the same operation as the treatment method provided in Example 1, and the only difference is that the negative electrode catalyst is changed to a columnar activated carbon without Re-Ti loading (i.e. activated carbon raw material), and the remaining steps are the same as Example 1. The test results are shown in Table 10.

[0075] Table 10 Test results

[0076] Comparative Example 8 This comparative example provides a treatment method of battery soaking discharge wastewater, which has the same operation as the treatment method provided in Example 1, and the only difference is that no catalyst is used, i.e. no catalyst is added in the mesh bag, and the remaining steps are the same as Example 1. The test results are shown in Table 11.

[0077] Table 11 Test results

[0078] Comparative Example 9 This comparative example provides a treatment method of battery soaking discharge wastewater, which has the same operation as the treatment method provided in Example 1, and the only difference is that 3 g of sodium sulfate is not used, and the remaining steps are the same as Example 1. The test results are shown in Table 12.

[0079] Table 12 Test results

[0080] According to Tables 1-12, (1) According to Comparative Example 1 and Comparative Examples 1-2, within the pH range of 2.5-3.5, the removal effects of COD and TP are excellent, meeting the discharge requirements. If the range is exceeded, the removal effects of COD and TP will decrease, so as to fail to meet the discharge standards.

[0081] (2) Comparative Example 1~Example 3, Comparative Example 3~Comparative Example 4, in the current density is 5~20mA / cm 2 The removal effects of COD and TP are excellent, and meet the discharge requirements, and the removal rates of COD and TP are decreased when the current density is out of the range.

[0082] (3) Comparative Example 1, Comparative Example 5 and 6, the micro-electric oxygen electro-catalytic oxidation time is shortened, and COD and TP cannot be fully decomposed and oxidized, and the removal rates are decreased.

[0083] (4) Comparative Example 1 and Comparative Example 7, when the columnar activated carbon is used as the catalyst, that is, Re and Ti are not loaded, the removal rates of TP and COD are decreased, and the discharge standards cannot be met.

[0084] (5) Comparative Example 1 and Comparative Example 8, the catalyst is not added in the negative electrode net bag, the removal rate of COD is greatly decreased, TP has no obvious removal effect, and the discharge standards cannot be met, that is, the electrolysis cannot effectively remove COD and TP.

[0085] (6) Comparative Example 1 and Comparative Example 9, the electrolyte salt sodium sulfate is not added in the micro-electric oxygen electro-catalytic oxidation process, and the removal effects of COD and TP are decreased.

[0086] In conclusion, the treatment method provided by the embodiment of the application is used, and the COD, F - and TP of the treated effluent meet the third standard of the Comprehensive Discharge Standard for Sewage (GB8978-1996). Compared with the traditional combined process of high-temperature acidolysis, biochemical treatment and Fenton, the treatment process is simple, and the treatment efficiency is higher.

[0087] The above only describes the preferred embodiments of the application and is not used to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A method for treating battery immersion discharge wastewater, characterized by, The application relates to a method for treating battery soaking and discharging wastewater. The battery soaking and discharging wastewater is pretreated to remove fluorine ions, sulfate ions and phosphate ions; Two-stage micro-electrolysis electro-catalytic oxidation is performed on the pretreated wastewater, wherein the conditions of each stage of the micro-electrolysis electro-catalytic oxidation include that a catalyst is activated carbon loaded with Re-Ti bimetal, 1-6 g of electrolyte salt is added per liter of the pretreated wastewater, and the pH of the pretreated wastewater is 2.5-3.

5.

2. The method for treating battery immersion discharge wastewater according to claim 1, characterized in that, The two-stage micro-electrolysis electro-catalytic oxidation includes that the pretreated wastewater is subjected to first-stage micro-electrolysis electro-catalytic oxidation, the pH is adjusted to 2.5-3.5, and then the pretreated wastewater is subjected to second-stage micro-electrolysis electro-catalytic oxidation. Preferably, aeration is performed during the first-stage micro-electrolysis electro-catalytic oxidation and the second-stage micro-electrolysis electro-catalytic oxidation.

3. The method of claim 2, wherein the battery immersion discharge wastewater is treated by a method comprising: The conditions of the two-stage micro-electrolysis electro-catalytic oxidation meet the following requirements: (1) The conditions of the first-stage micro-electrolysis electro-catalytic oxidation include: current density of 5-20 mA / cm 2 , electrolysis time of 3-5 h; (2) The conditions of the second-stage micro-electrolysis electro-catalytic oxidation include: current density of 5-20 mA / cm 2 , electrolysis time of 1-3 h.

4. The method of claim 1-3, wherein the battery immersion discharge wastewater is treated by the method of claim 1-3. The raw material for forming the activated carbon loaded with Re-Ti bimetal meets the following requirements: (1) The activated carbon raw material is columnar; (2) The length of the activated carbon raw material is 8-120 mm; (3) The specific surface area of the activated carbon raw material is 150-200 m2 / g; (4) The porosity of the activated carbon raw material is 60%-70%.

5. The method of claim 1-3, wherein the battery immersion discharge wastewater is treated by the method of claim 1-3. The pretreatment includes that the battery soaking and discharging wastewater is mixed with a calcium-containing compound to remove fluorine ions, sulfate ions and phosphate ions, and then a carbonate is added to remove calcium ions.

6. The method of claim 5, wherein the battery soak discharge wastewater is treated by a method comprising: The pretreatment meets the following conditions: (1) The amount of the calcium-containing compound is 1.0-1.5 times the total theoretical molar amount of the sulfate ions, fluorine ions and phosphate ions to be removed; (2) The reaction time of the battery soaking and discharging wastewater with the calcium-containing compound is 0.5-1 h; (3) The amount of the carbonate is 1.0-1.5 times the theoretical molar amount of the calcium ions to be completely removed; (4) The reaction time with the carbonate is 0.5-1 h.

7. The method of claim 5, wherein the battery soak discharge wastewater is treated by a method comprising: The calcium-containing compound includes calcium oxide or calcium hydroxide; and the carbonate includes sodium carbonate.

8. The method of claim 1-3, wherein the battery soak discharge wastewater is treated by, The battery soaking and discharging wastewater meets at least one of the following requirements: (1) COD is 4000-5000 mg / L; (2) F - 100-400 mg / L; (3) TP is 370-520 mg / L; (4) The pH of the battery soaking and discharging wastewater is 5-7.

9. The method of claim 1, wherein the battery soak discharge wastewater is treated by a method comprising: The application further relates to regeneration of the catalyst in the micro-electrolysis electro-catalytic oxidation. Preferably, when the TP concentration in the effluent formed after the two-stage micro-electrolysis electro-catalytic oxidation treatment exceeds 8 mg / L or the COD concentration exceeds 500 mg / L, the catalyst in the first-stage micro-electrolysis electro-catalytic oxidation is regenerated.

10. The method of claim 9, wherein the battery immersion discharge wastewater is treated by a method comprising: The regeneration operation includes that the positive and negative electrodes are reversed, water, acid and electrolyte salt are added, and an electric current is applied. Preferably, the regeneration conditions meet any one of the following requirements: (1) 1-3 g of the electrolyte salt is added per liter of the water, (2) 1-1.5 ml of the acid is added per liter of the water; (3) The acid is concentrated sulfuric acid. (4) current density is 25-35 mA / cm 2 , electrolysis time is 20-40 min; Preferably, the application further relates to that the regenerated catalyst is used in the second-stage micro-electrolysis electro-catalytic oxidation after the regeneration is completed, the catalyst originally used in the second-stage micro-electrolysis electro-catalytic oxidation is used in the first-stage micro-electrolysis electro-catalytic oxidation, and the regeneration liquid is returned to the pretreatment.

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