Lead-acid battery wastewater treatment method

Abstract

The present invention discloses a lead-acid battery wastewater treatment method, comprising: (1) collecting wastewater; (2) transporting the wastewater to a primary adsorption tank for adsorption treatment to obtain a filtrate treated by the primary adsorption treatment; (3) adding the filtrate treated by the primary adsorption treatment to a reaction tank for reaction flocculation to obtain a mud-water mixture; (4) settling the mud-water mixture, collecting an upper clear liquid and a lower sludge; (5) reducing and adjusting the lower sludge, and then further dehydrating and reducing the lower sludge to obtain a filter press filtrate and a dehydrated sludge; (6) mixing the upper clear liquid and the filter press filtrate and transporting them to a secondary adsorption tank for adsorption treatment to obtain a secondary adsorption filtrate; (7) testing the filtrate treated by the secondary adsorption treatment, collecting it into a clear water tank after the test meets the standard, and returning it to the primary adsorption tank or the secondary adsorption tank for further treatment until it meets the standard if it does not meet the standard. The lead-acid battery wastewater treatment method of the present invention is simple to operate, can effectively treat lead ions and suspended matter in wastewater, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a lead-acid battery wastewater treatment method. Background Art

[0002] Lead-acid battery production generates lead-acid wastewater. This wastewater, with its complex composition, is highly toxic, highly acidic, and difficult to degrade. If left untreated, it can severely impact the health of workers and pose serious risks to the surrounding environment. During lead-acid battery manufacturing, discharged wastewater primarily comes from processes such as acid preparation, plate coating, and formation, as well as from ventilation and dust removal. It also includes wastewater from rinsing formation plates, post-assembly cleaning of lead-acid batteries, workshop wastewater containing lead fumes, lead dust treatment, floor washing, centralized bathing wastewater, lead-containing laundry wastewater, and high-salt wastewater from pure water preparation. These wastewaters primarily contain lead powder, molten lead, lead sulfate, sulfuric acid, other organic additives, and engine oil. Lead, a Class I pollutant, poses a significant risk if not properly treated.

[0003] Current methods for treating lead-containing wastewater include chemical precipitation, ion exchange, and electrodialysis. Chemical precipitation is the most widely used technology for treating lead-containing wastewater. However, existing treatment processes are complex and energy-intensive. Summary of the Invention

[0004] In view of this, the present invention provides a lead-acid battery wastewater treatment method to solve the above-mentioned problems.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A method for treating lead-acid battery wastewater comprises the following steps:

[0007] (1) Wastewater collection: The lead-acid battery wastewater is collected and stored in a wastewater storage tank, and the water quality and water volume of the lead-acid battery wastewater are comprehensively adjusted to ensure uniform quality and volume;

[0008] (2) Primary adsorption treatment: The wastewater in the wastewater storage tank in step (1) is transferred to a primary adsorption tank, the pH value is adjusted to 5-6, an adsorbent is added at a dosage of 0.5-1.5 g / L, and adsorption treatment is performed for 6-10 hours, and the adsorption treatment is performed by filtering to obtain a filtrate of the primary adsorption treatment;

[0009] (3) Reaction treatment: the filtrate from the primary adsorption treatment in step (2) is added to a reaction tank, lime emulsion is added to adjust the pH value to 7.5-8.5, and then polyaluminum chloride is added to react. After the reaction is completed, polyacrylamide is added to flocculate to obtain a mud-water mixture;

[0010] (4) Sedimentation treatment: The mud-water mixture in step (3) is transported to a sedimentation tank to sediment the physicochemical sludge produced by the sedimentation reaction, and the upper clear liquid and lower sludge are collected;

[0011] (5) Dehydration treatment: The lower layer of sludge in step (4) is transported to a sludge thickening tank for weight reduction and then pumped into a high-pressure diaphragm plate and frame filter press for further dehydration and weight reduction to obtain a filter press filtrate and dehydrated sludge;

[0012] (6) Secondary adsorption treatment: The supernatant in step (3) and the filter press filtrate in step (5) are mixed and transported to a secondary adsorption tank, the pH value is adjusted to 6 to 9, an adsorbent is added at a dosage of 0.5 to 1.5 g / L, and adsorption treatment is carried out for 6 to 10 hours, and the mixture is filtered to obtain a filtrate treated with secondary adsorption;

[0013] (7) Testing and collection: The filtrate from the secondary adsorption treatment in step (6) is tested, and if the test results meet the standards, it is collected and put into the clear water tank. If the test results do not meet the standards, it is returned to the primary adsorption tank or the secondary adsorption tank according to the standards and treated again until it meets the standards;

[0014] Wherein, the adsorbents in step (2) and step (6) are both modified chitosan-based magnetic biochar adsorbents.

[0015] Furthermore, the dosage of lime emulsion in step (3) is 2-3 kg / m 3 .

[0016] Furthermore, in the step (3), the Al2O3 content in the polyaluminium chloride is 20% to 30%, and the dosage of the polyaluminium chloride is 0.1 to 0.45 kg / m 3 .

[0017] Furthermore, in step (3), the molecular weight of polyacrylamide is 10 million to 14 million, and the dosage of polyacrylamide is 0.005 to 0.01 kg / m 3 .

[0018] Furthermore, the sedimentation tank in step (4) is a vertical flow type, and the surface load of the sedimentation tank is 0.1 to 1.0 m 3 / (m2·h).

[0019] Furthermore, the preparation method of the modified chitosan-based magnetic biochar adsorbent comprises the following steps:

[0020] S1. The biomass was mixed with Fe(NO3)3·9H2O and added to anhydrous ethanol. The mixture was stirred at room temperature and then dispersed by ultrasonication. The mixture was dried at 60-70°C. The dried biomass was placed in a container, placed in a tubular furnace and introduced with nitrogen. The temperature was raised to 500-600°C under a nitrogen atmosphere, sintered at a constant temperature, and cooled at room temperature to obtain magnetic biochar.

[0021] S2. Stir and heat the polypropylene glycol to 30-40°C, slowly add itaconic anhydride and 4-dimethylaminopyridine in sequence, then heat to 50-60°C and stir for 1-2 hours, and cool to room temperature to obtain a modifier;

[0022] S3. Weigh, by weight, 10-20 parts of chitosan powder, 100-120 parts of 1% acetic acid solution, 6-10 parts of magnetic biochar, 12-16 parts of modifier, 6-8 parts of polyvinyl alcohol, and 40-50 parts of 1% sodium tripolyphosphate solution;

[0023] S4. Add chitosan powder to acetic acid solution, stir and dissolve at room temperature, then add magnetic biochar and modifier, stir evenly and heat in a water bath to 60-70°C, then add polyvinyl alcohol and continue stirring until mixed evenly, then slowly add dropwise to sodium tripolyphosphate solution, let stand and age after addition is complete, filter, take out solid and dry to obtain modified chitosan-based magnetic biochar adsorbent.

[0024] Furthermore, the biomass in step S1 is at least one of peanut shells, buckwheat shells, coconut skins, wood chips, and bamboo chips.

[0025] Furthermore, the mass ratio of the biomass to Fe(NO3)3·9H2O in step S1 is 1:0.5-2.

[0026] Furthermore, the heating rate in step S1 is 5-10° C. / min, and the sintering time is 2-3 h.

[0027] Furthermore, the mass ratio of polypropylene glycol, itaconic anhydride and 4-dimethylaminopyrrolidone in step S2 is 40:22:0.1-1.

[0028] The beneficial effects of the present invention are:

[0029] The present invention relates to a lead-acid battery wastewater treatment method.

[0030] (1) The present invention uses chitosan as a carrier, modifies it and loads magnetic biochar as an adsorbent. Since there are a large number of hydroxyl and amino groups in the chitosan molecule as active sites, they can bind to Pb through chelation, hydrogen bonding or electrostatic attraction. 2+ The chitosan was structurally modified using polypropylene glycol and itaconic anhydride to introduce more active sites on the chitosan to increase its adsorption capacity. The pores of the adsorbent were increased while protecting the hydroxyl and amino groups on the surface of the chitosan, making the surface of the adsorbent rough and not smooth, thereby increasing the surface area of ​​the adsorbent and facilitating the adsorption of Pb. 2+ Contact with the adsorbent makes more active sites on the adsorbent surface available, thereby increasing the adsorption capacity. 2+The lone pair electrons on the O atom of the ether bond form a bond, which reduces the electron density of the adjacent C atom and forms a CO-Pb bond, thereby further improving the adsorbent's ability to absorb Pb. 2+ Adsorption effect;

[0031] Biochar can bind Pb through π-π interaction and hydrogen bonding. 2+ Adsorbed on oxygen-containing functional groups such as C=O, CO and OH of the material, the surface molecules of biochar can react with Pb 2+ Producing van der Waals force, Pb 2+ Either adsorbed on the surface of biochar or diffused into the pores, while the negatively charged surface of biochar can promote the positively charged Pb 2+ Electrostatic attraction with biochar. With the increase of pH value, the negative charge on the surface of biochar increases and its Zeta potential decreases. 2+ The adsorption capacity becomes stronger;

[0032] The negatively charged groups on the biochar surface and the positively charged Pb in the wastewater 2+ Coulomb force is generated to exchange metals in biomass. Metals in biomass cannot be decomposed under high temperature conditions. Higher pyrolysis temperature can promote the enrichment of metals in biochar. K in biochar + 、Na + Mg 2+ The metal content will increase with the increase of pyrolysis temperature. The high activity and fluidity of alkali metals can enhance the ion exchange effect. 2+ With K + and Na + Due to the electrostatic outer sphere complexation, metal exchange occurs, which effectively increases the adsorbent's Pb 2+ Adsorption effect;

[0033] The mineral components in biochar can also enhance adsorption activity, thereby improving adsorption performance. Soluble phosphates and carbonates can react with Pb 2+ Co-precipitation forms stable PbCO3. The pH of biochar is generally above 8, which will promote the biochar to Pb 2+ The precipitation effect of Pb 2+ When the pH value of the biochar solution is very high, the Pb 2+ It will be converted into hydroxide and precipitated on the surface of biochar. At the same time, the present invention also uses Fe(NO3)3·9H2O to impregnate and pyrolyze biomass to prepare magnetic biochar, so that the adsorbent will generate magnetism to facilitate subsequent separation and treatment.

[0034] (2) The present invention uses lime emulsion as a pH regulator, polyaluminium chloride and polyacrylamide as flocculants and coagulants respectively to treat lead-acid battery wastewater. Lime emulsion is added to the wastewater to gradually raise the pH to 7.5-8.5. As the pH in the wastewater increases, the concentration of hydroxide ions in the aqueous solution increases, and the Pb in the water decreases. 2+ With OH - Combined to form Pb(OH)2 precipitation, and with OH - As the amount of Pb(OH)2 increases, the reaction equilibrium moves towards precipitation. Since the generated Pb(OH)2 precipitate is a fine particle, the sedimentation effect is poor. PAC is an aluminum salt flocculant. After adding it to water, Al 3+ With F - The combination of aluminum salt hydrolysis intermediates and the final generated Al(OH)3 forms various alum flowers in the solution, which have ligand exchange, physical adsorption, and sweeping effects on lead ions. At the same time, it can also promote the formation and growth of Pb(OH)2 precipitation particles, and ultimately form the generated Pb(OH)2 into a precipitate in water, which is separated from the treated clean water. Finally, PAM is added to cause the suspended matter to flocculate through electrical neutralization and bridging adsorption, accelerating the sedimentation of particles in the suspension, significantly accelerating solution clarification and promoting filtration. DETAILED DESCRIPTION

[0035] The present invention will be described in further detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto. For process parameters not particularly noted, conventional techniques may be used.

[0036] The present invention provides a modified chitosan-based magnetic biochar adsorbent for treating lead-acid battery wastewater. The preparation method of the adsorbent comprises the following steps:

[0037] S1. Biomass and Fe(NO3)3·9H2O are mixed in a mass ratio of 1:0.5-2, and then added to anhydrous ethanol. The mixture is stirred evenly at room temperature and then ultrasonically dispersed. The mixture is dried at a temperature of 60-70°C. The dried biomass is placed in a container, which is placed in a tubular furnace and nitrogen is introduced. The temperature is increased to 500-600°C at a heating rate of 5-10°C / min under a nitrogen atmosphere, and the mixture is sintered at a constant temperature for 2-3 hours. The mixture is cooled at room temperature to obtain magnetic biochar.

[0038] S2. Prepare raw materials according to the mass ratio of polypropylene glycol, itaconic anhydride and 4-dimethylaminopyridine of 40:22:0.1-1, stir the polypropylene glycol and heat it to 30-40°C, slowly add itaconic anhydride and 4-dimethylaminopyridine in sequence, then heat it to 50-60°C and stir for 1-2 hours, and cool at room temperature to obtain a modifier.

[0039] S3. Weigh 10 to 20 parts of chitosan powder, 100 to 120 parts of 1% acetic acid solution, 6 to 10 parts of magnetic biochar, 12 to 16 parts of modifier, 6 to 8 parts of polyvinyl alcohol, and 40 to 50 parts of 1% sodium tripolyphosphate solution respectively by weight.

[0040] S4. Add chitosan powder to acetic acid solution, stir and dissolve at room temperature, then add magnetic biochar and modifier, stir evenly and heat in a water bath to 60-70°C, then add polyvinyl alcohol and continue stirring until mixed evenly, then slowly add dropwise to sodium tripolyphosphate solution, let stand and age after addition is complete, filter, take out solid and dry to obtain modified chitosan-based magnetic biochar adsorbent.

[0041] The biomass in step S1 is at least one of peanut shells, buckwheat shells, coconut skins, wood chips, and bamboo chips.

[0042] The present invention provides a lead-acid battery wastewater treatment method, comprising the following steps:

[0043] (1) Collecting wastewater: Collect the lead-acid battery wastewater and store it in a wastewater storage tank. The water quality and quantity of the lead-acid battery wastewater are comprehensively adjusted to ensure uniform quality and quantity.

[0044] (2) Primary adsorption treatment: The wastewater in the wastewater storage tank in step (1) is transported to the primary adsorption tank, the pH value is adjusted to 5-6, and an adsorbent is added at a dosage of 0.5-1.5 g / L for adsorption treatment for 6-10 hours, and filtered to obtain a filtrate of the primary adsorption treatment.

[0045] (3) Reaction treatment: Add the filtrate from the first-stage adsorption treatment in step (2) into the reaction tank at a rate of 2 to 3 kg / m 3 Add lime emulsion at a dosage of 0.1-0.45 kg / m 3 Add 20% to 30% Al2O3 to polyaluminium chloride for reaction. After the reaction is complete, press 0.005 to 0.01 kg / m 3 Polyacrylamide with a molecular weight of 10 million to 14 million is added for flocculation to obtain a mud-water mixture.

[0046] (4) Sedimentation treatment: The mud-water mixture in step (3) is transported to a sedimentation tank, and the surface load of the sedimentation tank is controlled to be 0.1 to 1.0 m 3 / (m2·h), the physicochemical sludge produced by the sedimentation reaction, the supernatant and the lower sludge are collected.

[0047] (5) Dehydration treatment: The lower layer of sludge in step (4) is transported to a sludge thickening tank for weight reduction adjustment, and then pumped into a high-pressure diaphragm plate and frame filter press for further dehydration and weight reduction to obtain filter press filtrate and dehydrated sludge.

[0048] (6) Secondary adsorption treatment: The supernatant in step (3) and the filter press filtrate in step (5) are mixed and transported to a secondary adsorption tank, the pH value is adjusted to 6 to 9, and an adsorbent is added at a dosage of 0.5 to 1.5 g / L for adsorption treatment for 6 to 10 hours. The mixture is filtered to obtain a filtrate treated with secondary adsorption.

[0049] (7) Testing and collection: The filtrate from the secondary adsorption treatment in step (6) is tested. If the test results are satisfactory, the filtrate is collected and sent to a clean water tank. If the test results are not satisfactory, the filtrate is returned to the primary adsorption tank or the secondary adsorption tank for further treatment until the test results are satisfactory.

[0050] Example 1

[0051] The preparation method of the modified chitosan-based magnetic biochar adsorbent of this embodiment comprises the following steps:

[0052] S1. Peanut shells and Fe(NO3)3·9H2O were mixed in a mass ratio of 1:0.5 and added to anhydrous ethanol. The mixture was stirred evenly at room temperature and then ultrasonically dispersed. The mixture was dried at 60°C. The dried biomass was placed in a container, placed in a tubular furnace and introduced with nitrogen. The temperature was raised to 500°C at a heating rate of 5°C / min under a nitrogen atmosphere. The mixture was sintered at a constant temperature for 2 hours and cooled at room temperature to obtain magnetic biochar.

[0053] S2. Prepare raw materials according to the mass ratio of polypropylene glycol, itaconic anhydride and 4-dimethylaminopyridine of 40:22:0.1, stir the polypropylene glycol and heat it to 30°C, slowly add itaconic anhydride and 4-dimethylaminopyridine in sequence, then heat it to 50°C and stir for 1 hour, and cool to room temperature to obtain a modifier.

[0054] S3. Weigh 10 parts of chitosan powder, 100 parts of 1% acetic acid solution, 6 parts of magnetic biochar, 12 parts of modifier, 6 parts of polyvinyl alcohol, and 40 parts of 1% sodium tripolyphosphate solution by weight.

[0055] S4. Add chitosan powder to acetic acid solution, stir and dissolve at room temperature, then add magnetic biochar and modifier, stir evenly and heat in a water bath to 60°C, then add polyvinyl alcohol and continue stirring until mixed evenly, then slowly add dropwise to sodium tripolyphosphate solution, let stand and age after addition is complete, filter, take out solid and dry to obtain modified chitosan-based magnetic biochar adsorbent.

[0056] Example 2

[0057] The preparation method of the modified chitosan-based magnetic biochar adsorbent of this embodiment comprises the following steps:

[0058] S1. Buckwheat hulls and Fe(NO3)3·9H2O were mixed in a mass ratio of 1:1 and added to anhydrous ethanol. The mixture was stirred evenly at room temperature and then ultrasonically dispersed. The dried biomass was placed in a container, placed in a tubular furnace and introduced with nitrogen. The temperature was raised to 540°C at a heating rate of 8°C / min under a nitrogen atmosphere. The mixture was sintered at a constant temperature for 2.5 hours and cooled at room temperature to obtain magnetic biochar.

[0059] S2. Prepare raw materials according to the mass ratio of polypropylene glycol, itaconic anhydride and 4-dimethylaminopyridine of 40:22:0.5, stir the polypropylene glycol and heat it to 35°C, slowly add itaconic anhydride and 4-dimethylaminopyridine in sequence, then heat it to 55°C and stir for 1-2 hours, and cool to room temperature to obtain a modifier.

[0060] S3. Weigh 15 parts of chitosan powder, 110 parts of 1% acetic acid solution, 8 parts of magnetic biochar, 14 parts of modifier, 7 parts of polyvinyl alcohol, and 45 parts of 1% sodium tripolyphosphate solution by weight.

[0061] S4. Add chitosan powder to acetic acid solution, stir and dissolve at room temperature, then add magnetic biochar and modifier, stir evenly and heat in a water bath to 65°C, then add polyvinyl alcohol and continue stirring until mixed evenly, then slowly add dropwise to sodium tripolyphosphate solution, let stand and age after the addition is complete, filter, take out the solid and dry it to obtain a modified chitosan-based magnetic biochar adsorbent.

[0062] Example 3

[0063] The preparation method of the modified chitosan-based magnetic biochar adsorbent of this embodiment comprises the following steps:

[0064] S1. Coconut peel and Fe(NO3)3·9H2O were mixed in a mass ratio of 1:2 and added to anhydrous ethanol. The mixture was stirred evenly at room temperature and then ultrasonically dispersed. The mixture was dried at 70°C. The dried biomass was placed in a container, placed in a tubular furnace and introduced with nitrogen. The temperature was raised to 600°C at a heating rate of 10°C / min under a nitrogen atmosphere. The mixture was sintered at a constant temperature for 3 hours and cooled at room temperature to obtain magnetic biochar.

[0065] S2. Prepare raw materials according to the mass ratio of polypropylene glycol, itaconic anhydride and 4-dimethylaminopyridine of 40:22:1, stir the polypropylene glycol and heat it to 40°C, slowly add itaconic anhydride and 4-dimethylaminopyridine in sequence, then heat it to 60°C and stir for 2h, and cool to room temperature to obtain a modifier.

[0066] S3. Weigh 20 parts of chitosan powder, 120 parts of 1% acetic acid solution, 10 parts of magnetic biochar, 16 parts of modifier, 8 parts of polyvinyl alcohol, and 50 parts of 1% sodium tripolyphosphate solution by weight.

[0067] S4. Add chitosan powder to acetic acid solution, stir and dissolve at room temperature, then add magnetic biochar and modifier, stir evenly and heat in a water bath to 70°C, then add polyvinyl alcohol and continue stirring until mixed evenly, then slowly add dropwise to sodium tripolyphosphate solution, let stand and age after the addition is complete, filter, take out the solid and dry it to obtain a modified chitosan-based magnetic biochar adsorbent.

[0068] Example 4

[0069] The adsorbent used in this embodiment to treat lead-acid battery wastewater is the modified chitosan-based magnetic biochar adsorbent prepared in Example 1. The lead-acid battery wastewater treatment method of this embodiment includes the following steps:

[0070] (1) Collecting wastewater: Collect the lead-acid battery wastewater and store it in a wastewater storage tank. The water quality and quantity of the lead-acid battery wastewater are comprehensively adjusted to ensure uniform quality and quantity.

[0071] (2) Primary adsorption treatment: The wastewater in the wastewater storage tank in step (1) was transported to the primary adsorption tank, the pH value was adjusted to 5, and an adsorbent was added at a dosage of 0.5 g / L for adsorption treatment for 6 h. The adsorption was then filtered to obtain a filtrate from the primary adsorption treatment.

[0072] (3) Reaction treatment: Add the filtrate of the first-stage adsorption treatment in step (2) into the reaction tank at a rate of 2 kg / m 3 Add lime emulsion at a dosage of 0.1 kg / m 3 Add 20% Al2O3 to polyaluminium chloride for reaction. After the reaction is completed, press 0.005kg / m 3 Polyacrylamide with a molecular weight of 10 million is added for flocculation to obtain a mud-water mixture.

[0073] (4) Sedimentation treatment: The mud-water mixture in step (3) is transported to a sedimentation tank, and the surface load of the sedimentation tank is controlled to be 0.1m 3 / (m2·h), the physicochemical sludge produced by the sedimentation reaction, the supernatant and the lower sludge are collected.

[0074] (5) Dehydration treatment: The lower layer of sludge in step (4) is transported to a sludge thickening tank for weight reduction adjustment, and then pumped into a high-pressure diaphragm plate and frame filter press for further dehydration and weight reduction to obtain filter press filtrate and dehydrated sludge.

[0075] (6) Secondary adsorption treatment: The supernatant in step (3) and the filter press filtrate in step (5) are mixed and transported to a secondary adsorption tank, the pH value is adjusted to 6, and an adsorbent is added at a dosage of 0.5 g / L for adsorption treatment for 6 hours. The mixture is filtered to obtain a filtrate treated with secondary adsorption.

[0076] (7) Testing and collection: The filtrate from the secondary adsorption treatment in step (6) is tested. If the test results are satisfactory, the filtrate is collected and sent to a clean water tank. If the test results are not satisfactory, the filtrate is returned to the primary adsorption tank or the secondary adsorption tank for further treatment until the test results are satisfactory.

[0077] Example 5

[0078] The adsorbent used in this embodiment to treat lead-acid battery wastewater is the modified chitosan-based magnetic biochar adsorbent prepared in Example 2. The lead-acid battery wastewater treatment method of this embodiment includes the following steps:

[0079] (1) Collecting wastewater: Collect the lead-acid battery wastewater and store it in a wastewater storage tank. The water quality and quantity of the lead-acid battery wastewater are comprehensively adjusted to ensure uniform quality and quantity.

[0080] (2) Primary adsorption treatment: The wastewater in the wastewater storage tank in step (1) was transported to the primary adsorption tank, the pH value was adjusted to 5.5, and an adsorbent was added at a dosage of 1 g / L for adsorption treatment for 8 hours. The adsorption was then filtered to obtain a filtrate from the primary adsorption treatment.

[0081] (3) Reaction treatment: Add the filtrate of the primary adsorption treatment in step (2) into the reaction tank at a rate of 2.5 kg / m 3 Add lime emulsion at a dosage of 0.25kg / m 3 Add 25% Al2O3 to polyaluminium chloride for reaction. After the reaction is completed, press 0.007kg / m 3 Polyacrylamide with a molecular weight of 12 million is added for flocculation to obtain a mud-water mixture.

[0082] (4) Sedimentation treatment: The mud-water mixture in step (3) is transported to a sedimentation tank, and the surface load of the sedimentation tank is controlled to be 0.5m 3 / (m2·h), the physicochemical sludge produced by the sedimentation reaction, the supernatant and the lower sludge are collected.

[0083] (5) Dehydration treatment: The lower layer of sludge in step (4) is transported to a sludge thickening tank for weight reduction adjustment, and then pumped into a high-pressure diaphragm plate and frame filter press for further dehydration and weight reduction to obtain filter press filtrate and dehydrated sludge.

[0084] (6) Secondary adsorption treatment: The supernatant in step (3) and the filter press filtrate in step (5) are mixed and transported to a secondary adsorption tank, the pH value is adjusted to 7, and an adsorbent is added at a dosage of 1 g / L for adsorption treatment for 8 hours. The mixture is filtered to obtain a filtrate treated with secondary adsorption.

[0085] (7) Testing and collection: The filtrate from the secondary adsorption treatment in step (6) is tested. If the test results are satisfactory, the filtrate is collected and sent to a clean water tank. If the test results are not satisfactory, the filtrate is returned to the primary adsorption tank or the secondary adsorption tank for further treatment until the test results are satisfactory.

[0086] Example 6

[0087] The adsorbent used in this embodiment to treat lead-acid battery wastewater is the modified chitosan-based magnetic biochar adsorbent prepared in Example 3. The lead-acid battery wastewater treatment method of this embodiment includes the following steps:

[0088] (1) Collecting wastewater: Collect the lead-acid battery wastewater and store it in a wastewater storage tank. The water quality and quantity of the lead-acid battery wastewater are comprehensively adjusted to ensure uniform quality and quantity.

[0089] (2) Primary adsorption treatment: The wastewater in the wastewater storage tank in step (1) was transported to the primary adsorption tank, the pH value was adjusted to 6, and an adsorbent was added at a dosage of 1.5 g / L for adsorption treatment for 10 h. The adsorption was then filtered to obtain a filtrate from the primary adsorption treatment.

[0090] (3) Reaction treatment: Add the filtrate from the first-stage adsorption treatment in step (2) into the reaction tank at a rate of 2 to 3 kg / m 3 Add lime emulsion at a dosage of 0.45 kg / m 3 Add 30% Al2O3 to polyaluminium chloride for reaction. After the reaction is completed, press 0.01kg / m 3 Polyacrylamide with a molecular weight of 14 million is added for flocculation to obtain a mud-water mixture.

[0091] (4) Sedimentation treatment: The mud-water mixture in step (3) is transported to a sedimentation tank, and the surface load of the sedimentation tank is controlled to be 1.0m 3 / (m2·h), the physicochemical sludge produced by the sedimentation reaction, the supernatant and the lower sludge are collected.

[0092] (5) Dehydration treatment: The lower layer of sludge in step (4) is transported to a sludge thickening tank for weight reduction adjustment, and then pumped into a high-pressure diaphragm plate and frame filter press for further dehydration and weight reduction to obtain filter press filtrate and dehydrated sludge.

[0093] (6) Secondary adsorption treatment: The supernatant in step (3) and the filter press filtrate in step (5) were mixed and transported to a secondary adsorption tank, the pH value was adjusted to 8, and an adsorbent was added at a dosage of 1.5 g / L for adsorption treatment for 10 h. The mixture was filtered to obtain a filtrate treated with secondary adsorption.

[0094] (7) Testing and collection: The filtrate from the secondary adsorption treatment in step (6) is tested. If the test results are satisfactory, the filtrate is collected and sent to a clean water tank. If the test results are not satisfactory, the filtrate is returned to the primary adsorption tank or the secondary adsorption tank for further treatment until the test results are satisfactory.

[0095] Comparative Example 1

[0096] The lead-acid battery wastewater treatment method of this comparative example is substantially the same as the treatment method of Example 4, the difference being that the adsorbents used in the primary adsorption treatment and the secondary adsorption treatment of this comparative example are both activated carbon.

[0097] Comparative Example 2

[0098] The lead-acid battery wastewater treatment method of this comparative example is a coagulation sedimentation method. In this method, the oil substances are first separated by the oil separator and then enter the neutralization tank. The pH of the wastewater is adjusted to about 6 in the primary pH adjustment tank, and the flocculant polyaluminum chloride and the coagulant aid polyacrylamide are added to remove some of the pollutants Pb 2+ Then, to fully precipitate Pb 2+ The pH is adjusted to approximately 10.5 in a secondary pH adjustment tank, followed by solid-liquid separation in an inclined plate sedimentation tank. Part of the wastewater is used as recycled water, while the remainder enters an acid adjustment tank. The sludge is compacted by a filter press and transported to a designated treatment facility. After acid adjustment, the wastewater passes through an intermediate water pump and enters a mechanical filter to remove suspended impurities.

[0099] Experimental example

[0100] The water quality of the lead-acid battery wastewater treated in Examples 4 to 6 and Comparative Examples 1 to 2 is shown in Table 1:

[0101] Table 1: Lead-acid battery wastewater quality table

[0102]

[0103] The effluent water quality complies with the "Battery Industry Pollutant Emission Standard" (GB30484-2013). The pH value, total lead, suspended solids content and chemical oxygen demand of the effluent water of Examples 4 to 6 and Comparative Examples 1 to 2 were tested respectively. The specific test results are shown in Table 2:

[0104] Table 2: Statistics of effluent water quality test results

[0105]

[0106] As shown in Table 2, by comparing Example 4 with Comparative Example 1, the adsorbent of the present invention has better adsorption performance than activated carbon. This is because the present invention uses polypropylene glycol and itaconic anhydride to structurally transform chitosan, introduce more active sites on chitosan to improve its adsorption capacity, and increase the porosity of the adsorbent while protecting the hydroxyl and amino groups on the surface of chitosan, making the surface of the adsorbent rough and not smooth, thereby increasing the surface area of ​​the adsorbent, which is beneficial to the adsorption of Pb 2+ Contact with the adsorbent makes more active sites on the adsorbent surface available, thereby increasing the adsorption capacity. 2+ The lone pair electrons on the O atom of the ether bond form a bond, which reduces the electron density of the adjacent C atom and forms a CO-Pb bond, thereby further improving the adsorbent's ability to absorb Pb. 2+ adsorption effect.

[0107] By comparing Example 4 with Comparative Example 2, the effluent treated by the lead-acid battery wastewater treatment method of the present invention has a total lead content of less than 0.2 mg / L. This is because the present invention uses chitosan as a carrier, modifies it and loads magnetic biochar as an adsorbent. There are a large number of hydroxyl and amino groups in the chitosan molecule as active sites, which can bind to Pb through chelation, hydrogen bonding or electrostatic attraction. 2+ Forming complexes, while biochar binds Pb through π-π interactions and hydrogen bonds 2+ Adsorbed onto oxygen-containing functional groups such as C=O, CO and OH of the material, the negatively charged groups on the surface of biochar and the positively charged Pb 2+ Coulomb force is generated and exchanged, K in biochar + 、Na + Mg 2+ The metal content will increase with the increase of pyrolysis temperature. The high activity and fluidity of alkali metals can enhance the ion exchange effect. 2+ With K + and Na + Due to the electrostatic outer sphere complexation, metal exchange occurs, which effectively increases the adsorbent's Pb 2+ adsorption effect.

[0108] Therefore, the lead-acid battery wastewater treatment method of the present invention is simple to operate, can effectively treat lead ions and suspended matter in wastewater, and has broad application prospects.

[0109] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for treating lead-acid battery wastewater, characterized in that: The following steps are involved: (1) Wastewater collection: Collect the lead-acid battery wastewater and store it in a wastewater storage tank, and comprehensively adjust the water quality and water volume of the lead-acid battery wastewater to ensure uniform quality and volume; (2) Primary adsorption treatment: The wastewater in the wastewater storage tank in step (1) is transported to the primary adsorption tank, the pH value is adjusted to 5-6, and an adsorbent is added at a dosage of 0.5-1.5 g / L for adsorption treatment for 6-10 hours, and filtered to obtain a filtrate treated with primary adsorption; (3) Reaction treatment: the filtrate from the primary adsorption treatment in step (2) is added to the reaction tank, lime emulsion is added to adjust the pH value to 7.5-8.5, and then polyaluminum chloride is added to react. After the reaction is completed, polyacrylamide is added for flocculation to obtain a mud-water mixture; (4) Sedimentation treatment: The mud-water mixture in step (3) is transported to a sedimentation tank, and the physical and chemical sludge produced by the sedimentation reaction is collected, and the upper clear liquid and the lower sludge are collected; (5) Dehydration treatment: The lower layer of sludge in step (4) is transported to a sludge thickening tank for weight reduction and then pumped into a high-pressure diaphragm plate and frame filter press for further dehydration and weight reduction to obtain filter press filtrate and dehydrated sludge; (6) Secondary adsorption treatment: The supernatant in step (3) and the filter press filtrate in step (5) are mixed and transported to a secondary adsorption tank, the pH value is adjusted to 6-9, and an adsorbent is added at a dosage of 0.5-1.5 g / L for adsorption treatment for 6-10 hours, and filtered to obtain a filtrate treated with secondary adsorption; (7) Testing and collection: The filtrate from the secondary adsorption treatment in step (6) is tested. If the test results are satisfactory, the filtrate is collected and sent to the clean water tank. If the test results are not satisfactory, the filtrate is returned to the primary adsorption tank or the secondary adsorption tank for further treatment until the test results are satisfactory. Wherein, the adsorbents in step (2) and step (6) are both modified chitosan-based magnetic biochar adsorbents, and the preparation method of the modified chitosan-based magnetic biochar adsorbent comprises the following steps: S1. Mix the biomass with Fe(NO3)3·9H2O and add it to anhydrous ethanol. Stir it evenly at room temperature and then disperse it by ultrasonic. Dry it at 60-70°C. Place the dried biomass in a container, put it in a tube furnace and introduce nitrogen. Heat it to 500-600°C under nitrogen atmosphere, sinter it at a constant temperature, and cool it at room temperature to obtain magnetic biochar. S2. Stir and heat the polypropylene glycol to 30-40°C, slowly add itaconic anhydride and 4-dimethylaminopyridine in sequence, then heat to 50-60°C and stir for 1-2 hours, and cool to room temperature to obtain a modifier; S3. Weigh, by weight, 10-20 parts of chitosan powder, 100-120 parts of 1% acetic acid solution, 6-10 parts of magnetic biochar, 12-16 parts of modifier, 6-8 parts of polyvinyl alcohol, and 40-50 parts of 1% sodium tripolyphosphate solution; S4. Add chitosan powder to acetic acid solution, stir and dissolve at room temperature, then add magnetic biochar and modifier, stir evenly and heat in a water bath to 60~70℃, then add polyvinyl alcohol and continue stirring until mixed evenly, then slowly add dropwise to sodium tripolyphosphate solution, let stand and age after addition is complete, filter, take out solid and dry to obtain modified chitosan-based magnetic biochar adsorbent.

2. The lead-acid battery wastewater treatment method according to claim 1, characterized in that: The dosage of lime emulsion in step (3) is 2-3 kg / m³.

3. The lead-acid battery wastewater treatment method according to claim 1, characterized in that: In the step (3), the Al2O3 content in the polyaluminium chloride is 20% to 30%, and the dosage of the polyaluminium chloride is 0.1 to 0.45 kg / m³.

4. The lead-acid battery wastewater treatment method according to claim 1, characterized in that: In the step (3), the molecular weight of polyacrylamide is 10 million to 14 million, and the dosage of polyacrylamide is 0.005 to 0.01 kg / m³.

5. The lead-acid battery wastewater treatment method according to claim 1, characterized in that: The sedimentation tank in step (4) is a vertical flow type, and the surface load of the sedimentation tank is 0.1~1.0m³ / (m2·h).

6. The lead-acid battery wastewater treatment method according to claim 1, characterized in that: The biomass in step S1 is at least one of peanut shells, buckwheat shells, coconut skins, wood chips, and bamboo chips.

7. The lead-acid battery wastewater treatment method according to claim 1, characterized in that: The mass ratio of the biomass to Fe(NO3)3·9H2O in step S1 is 1:0.5-2.

8. The lead-acid battery wastewater treatment method according to claim 1, characterized in that: The heating rate in step S1 is 5-10°C / min, and the sintering time is 2-3h.

9. The lead-acid battery wastewater treatment method according to claim 1, characterized in that: The mass ratio of polypropylene glycol, itaconic anhydride and 4-dimethylaminopyrrolidone in step S2 is 40:22:0.1~1.

Images