Solid powder for treating formaldehyde-containing wastewater as well as preparation method and application of solid powder

Abstract

The invention provides solid powder for treating formaldehyde-containing wastewater as well as a preparation method and application of the solid powder. The method comprises the following steps: stirring and mixing the waste of the hydrometallurgy device and water to obtain a mixture; performing high-temperature treatment on the mixture in a stirring state to obtain target solid powder; wherein the waste of the hydrometallurgy device comprises cobalt hydroxide, chromium hydroxide, polyaluminum chloride, polyacrylamide, activated carbon powder, phosphate kerosene and calcium hydroxide. Wherein the polyacrylamide is decomposed into ammonia gas under a high-temperature alkaline condition, so that the solid powder is expanded, and the solid surface area of the powder is greatly increased. The solid powder reagent has a good treatment effect on formaldehyde in wastewater of an acrylic acid device, peroxide-containing wastewater is fully utilized as an oxidizing agent to oxidize formaldehyde in the wastewater, the purpose of treating waste with waste is achieved, and the biochemical property of the wastewater is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and specifically relates to a solid powder for treating formaldehyde-containing wastewater, and a preparation method and application thereof. Background Art

[0002] In chemical enterprises, formaldehyde is widely used, so there are many sources of formaldehyde wastewater. Chemical enterprises use a large amount of formaldehyde raw materials in the process of producing resins, plastics, leather, fibers, preservatives and other products. Some of these formaldehyde components become waste left over after production. If they are not properly handled, they may become a serious source of pollution. The most harmful component in formaldehyde wastewater is of course a large amount of formaldehyde. Formaldehyde is extremely harmful to human health. It has been identified by the World Health Organization as a carcinogenic and teratogenic toxic substance. It seriously threatens the human sense of smell, liver and lung function and immune tissue. It is a world problem that is extremely difficult to solve. In addition to formaldehyde, there are also substances such as benzene, trioxymethylene, and dioxolane in formaldehyde wastewater, which are more or less polluting or toxic. Low-concentration formaldehyde wastewater will inhibit the growth of microorganisms and have a considerable impact on the ecological environment. High-concentration formaldehyde wastewater will further destroy proteins, kill microorganisms, and cause irreversible damage to the ecological environment.

[0003] Currently, the commonly used methods for treating formaldehyde wastewater include: biological method and Fenton oxidation method.

[0004] Biological treatment of formaldehyde-containing wastewater mostly adopts a combination of anaerobic and aerobic methods. Anaerobic organisms can treat high-concentration toxic and harmful wastewater; they can degrade formaldehyde into simple, stable compounds, and significantly remove COD in wastewater. Aerobic biological treatment can metabolize the small molecules produced by anaerobic biological treatment and eventually stabilize them as low-energy inorganic substances. Biological methods have the advantage of low operating costs, but due to the high biological toxicity of formaldehyde, biological methods can only treat low-concentration formaldehyde wastewater. It is difficult to treat wastewater with formaldehyde content higher than 500ppm.

[0005] Fenton's reagent method is to use Fe 2+ Combined with H2O2, under acidic conditions, hydroxyl radicals (·OH) are generated, which exert strong oxidative properties. Highly active hydroxyl radicals react with organic matter, promoting its degradation and mineralization into inorganic substances such as CO2 and H2O, and quickly and completely oxidize and degrade organic matter in a short time. Fenton reagent oxidation process is widely used in the field of industrial wastewater treatment due to its advantages such as simple operation, easy availability of reactants and low investment. Fenton oxidation method can treat high and low concentration formaldehyde wastewater, but the process uses Fe 2+ As a catalyst, a large amount of iron sludge is produced, which is treated as hazardous waste at a high cost.

[0006] Since the industrial production of acrylic acid was realized in the 1930s, the development of its process technology has gone through the cyanoethanol method, carbonyl synthesis method, ketene method, acrylonitrile hydrolysis method and propylene two-step oxidation method. At present, the propylene two-step oxidation method is the main production method of acrylic acid. In the process of producing acrylic acid by the propylene two-step oxidation method, water is needed to absorb the oxidation product, and the acrylic acid product is obtained through separation and refining processes. Therefore, a large amount of wastewater will be generated in the production process of acrylic acid and esters. The wastewater in the industrial production of acrylic acid and esters has the following characteristics: large amount of wastewater, high organic content, complex pollutant composition, and large water quality fluctuations. The production wastewater of acrylic acid and esters is a high-concentration organic industrial wastewater, with a chemical oxygen demand (CODCr) of generally 30000-50000 mg / L, which is strongly acidic, mainly containing acetic acid (3.0-6.0%), acrylic acid and esters (0.02-3.0%), formaldehyde (0.04-4%), toluene and other organic matter (0-2%), and a large amount of difficult-to-degrade and toxic and harmful pollutants, which is extremely difficult to handle.

[0007] During the production process of the PO / SM device, air is required to oxidize ethylbenzene into EBHP. This process will produce a large amount of wastewater containing peroxides. The wastewater is highly oxidizing and biologically toxic, making it difficult to treat.

[0008] In summary, it is necessary to develop a treatment process that is universal, can treat high and low concentrations of formaldehyde, does not produce solid waste, and does not cause secondary pollution. It can also utilize the strong oxidizing properties of peroxide to treat formaldehyde wastewater to achieve the purpose of treating waste with waste. Summary of the invention

[0009] One of the purposes of the present invention is to provide a method for preparing a solid powder for treating formaldehyde-containing wastewater, wherein the solid powder treats formaldehyde, promotes its oxidation to formic acid, reduces its biological toxicity, and has a stable treatment effect.

[0010] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0011] A method for preparing a solid powder for treating formaldehyde-containing wastewater, the method comprising the following steps:

[0012] S1: Waste from a hydrometallurgical plant is stirred and mixed with water to obtain a mixture;

[0013] S2: treating the mixture at high temperature under stirring to obtain a target solid powder;

[0014] Among them, the waste from the hydrometallurgical device described in S1 includes cobalt hydroxide, chromium hydroxide, polyaluminium chloride, polyacrylamide, activated carbon powder, phosphate kerosene and calcium hydroxide.

[0015] The raw materials of the powder reagents in the present invention are taken from the waste of the hydrometallurgical device, and the main components thereof contain a certain amount of alkaline substances. Under high temperature conditions, the alkaline substances promote the decomposition of the C-NH2 carbon-nitrogen bond of polyacrylamide, and combine to generate ammonia. Under the action of stirring, the ammonia is evenly distributed in the solid-liquid slurry. With high-temperature drying, a large number of porous structures are formed, which greatly increases the solid surface area of ​​the powder. As an additional effect, the organic peroxide contained in the powder is decomposed into hydroxyl radicals with strong oxidizing properties, and the macromolecular substances in the wastewater are decomposed into small molecular acids, and some small molecular carboxylic acids are further oxidized into CO2 and H2O.

[0016] In one embodiment of the present invention, the composition of the waste from the hydrometallurgical plant in S1 is as follows, based on the total mass of the waste after evaporation of water:

[0017] Cobalt hydroxide 5-25wt%, preferably 15-22wt%,

[0018] Chromium hydroxide 10-20wt%, preferably 12-15wt%,

[0019] Polyaluminium chloride 11~25wt%,

[0020] Polyacrylamide 3-12wt%, preferably 4-8wt%,

[0021] Activated carbon powder 5~25wt%,

[0022] Phosphate kerosene 3-10wt%, preferably 4-6wt%,

[0023] Calcium hydroxide 2-10wt%, preferably 3-5wt%.

[0024] In one embodiment of the present invention, the ratio of S1 hydrometallurgical plant waste to water is 1:(3-8), preferably 1:(4-6).

[0025] In one embodiment of the present invention, the temperature of the high temperature treatment in S2 is 100-130°C.

[0026] In one embodiment of the present invention, S2 is based on the weight of the solid powder, and the solid powder comprises the following components:

[0027] Cobalt hydroxide 5.5-25.5wt%, preferably 15-22wt%,

[0028] Chromium hydroxide 11-21wt%, preferably 13-16wt%,

[0029] Polyaluminium chloride 12~27wt%

[0030] Polyacrylamide 1-4wt%, preferably 1.2-2.5wt%,

[0031] Activated carbon powder 6~28wt%

[0032] Phosphate ester kerosene 3-12wt%, preferably 5-7wt%,

[0033] Calcium hydroxide 3-12wt%, preferably 4-7wt%.

[0034] Another object of the present invention is to provide a solid powder for treating wastewater containing formaldehyde.

[0035] A solid powder for treating formaldehyde-containing wastewater, wherein the solid powder is prepared by the above-mentioned preparation method, and based on the weight of the solid powder, the solid powder comprises the following components:

[0036] Cobalt hydroxide 5.5-25.5wt%, preferably 15-22wt%,

[0037] Chromium hydroxide 11-21wt%, preferably 13-16wt%,

[0038] Polyaluminium chloride 12~27wt%

[0039] Polyacrylamide 1-4wt%, preferably 1.2-2.5wt%,

[0040] Activated carbon powder 6~28wt%

[0041] Phosphate ester kerosene 3-12wt%, preferably 5-7wt%,

[0042] Calcium hydroxide 3-12wt%, preferably 4-7wt%.

[0043] Another object of the present invention is to provide a use of a solid powder for treating wastewater containing formaldehyde.

[0044] A use of a solid powder for treating wastewater containing formaldehyde, wherein the solid powder is the solid powder prepared by the above-mentioned preparation method, or is the above-mentioned solid powder, and the solid powder is used for treating wastewater containing formaldehyde, preferably for jointly treating wastewater containing peroxide and wastewater containing formaldehyde, and more preferably for jointly treating wastewater containing peroxide in PO / SM and wastewater containing formaldehyde in acrylic acid devices.

[0045] Another object of the present invention is to provide a method for jointly treating wastewater containing peroxide and wastewater containing formaldehyde.

[0046] A method for jointly treating wastewater containing peroxide and wastewater containing formaldehyde, the method adopts the solid powder prepared by the above preparation method, or is the above solid powder, and the method comprises the following steps:

[0047] SS1: Wastewater containing peroxide and wastewater containing formaldehyde are mixed to obtain mixed wastewater;

[0048] SS2: Adjust the pH value of mixed wastewater;

[0049] SS3: The mixed wastewater enters the reactor, and the solid powder for treating the wastewater containing formaldehyde is added into the reactor for reaction;

[0050] SS4: After the reaction is completed, the solid and liquid are separated, the solid is treated as hazardous waste, and the liquid meets the biochemical indicators and is discharged.

[0051] In one embodiment of the present invention, the total amount of peroxide in SS1 calculated as hydrogen peroxide is higher than the formaldehyde content, calculated as mass per unit time, and those skilled in the art can adjust it according to the needs of the actual treatment process; preferably, the peroxide-containing wastewater in SS1 comes from a PO / SM device; preferably, the organic peroxide content in the peroxide-containing wastewater in SS1 is ≤30000 mg / L, and COD is ≤80000 mg / L, and preferably the methyl hydroperoxide content in the peroxide-containing wastewater is ≤25000 mg / L; preferably, the formaldehyde-containing wastewater in SS1 comes from an acrylic acid device; preferably, the formaldehyde content in the formaldehyde-containing wastewater in SS1 is ≤40000 mg / L, and COD is ≤50000 mg / L.

[0052] In one embodiment of the present invention, the pH in SS2 is adjusted with a base or an acid.

[0053] In one embodiment of the present invention, the pH in SS2 is adjusted to 9-11.

[0054] In one embodiment of the present invention, a stirred tank reactor is used in SS3.

[0055] In one embodiment of the present invention, the amount of solid powder added to SS3 is 5-10 g / L.

[0056] In one embodiment of the present invention, the SS3 reaction temperature is 40-60°C, the mixed wastewater, and the reaction time is 2-5h.

[0057] In one embodiment of the present invention, the formaldehyde content in the liquid after SS4 separation is ≤700 mg / L, and the COD is ≤38000 mg / L.

[0058] In one application scheme of the present invention, wastewater enters an intermittent stirred tank reactor, powder reagents are added into the reactor, and adsorption-extraction-catalytic oxidation synergistic reaction is carried out on the surface of the powder reagent. The powder reagent has a porous structure, and under the impetus of stirring, it quickly contacts with peroxides. The stirring turbulence, phosphate substance extraction and porous surface structure jointly increase the diffusion mass transfer rate. The contacted peroxide decomposes into [OH] and [O], which have high oxidizability. In the process of contacting with formaldehyde, it is oxidized to formic acid, and the biochemical property is further improved. In addition, the increase in the temperature and reaction time of the formaldehyde oxidation reaction is conducive to the increase in the decomposition efficiency of peroxides and formaldehyde, but the corresponding operation and investment costs will increase. In addition, with the increase of time and temperature, a large amount of organic matter is converted into carbon dioxide or small molecular organic matter, and small molecular substances have high biochemical properties and are difficult to continue to react. Therefore, the reaction temperature and time need to be optimized. Unlike hydrogen peroxide-like peroxides, organic peroxides, especially methyl hydroperoxide in POSM wastewater, have low decomposition efficiency in the absence of catalysts at room temperature and pressure, and cannot be fully decomposed into hydroxyl radicals. However, in the presence of solid powders, their active sites greatly reduce the activation energy of the reaction, which will quickly decompose the organic peroxides into [OH], thereby decomposing and removing the organic matter.

[0059] In one application scheme of the present invention, unlike hydrogen peroxide-type peroxides, organic peroxides, especially methyl hydroperoxide in POSM wastewater, have a low decomposition efficiency at room temperature and pressure without a catalyst and cannot be fully decomposed into hydroxyl radicals. In the presence of a solid powder, its active sites greatly reduce the activation energy of the reaction, and the organic peroxides will be quickly decomposed and converted into [OH], thereby decomposing and removing the organic matter.

[0060] Compared with the prior art, the beneficial effects of the present invention are:

[0061] (1) The raw materials used in the present invention are solid waste from the device, which is simple and easy to obtain.

[0062] (2) After simple and effective treatment, solid waste can be converted into porous additives with excellent effects, and the treatment process is simple.

[0063] (3) This scheme proposes a method for jointly treating wastewater containing peroxide and formaldehyde, making full use of the oxidizing property of peroxide to remove formaldehyde-like organic matter, thereby achieving the purpose of treating waste with waste. DETAILED DESCRIPTION

[0064] The technical scheme of the present invention and its effects are further described below by specific examples. The following examples are only used to illustrate the content of the present invention and are not used to limit the protection scope of the present invention. Simple changes made to the present invention by applying the concept of the present invention are all within the scope of the protection claimed by the present invention.

[0065] Batch reactor, purchased from Anhui Wufu Fluid Equipment Co., Ltd.;

[0066] Powder raw materials, Wanhua Chemical Co., Ltd. hydrometallurgical unit wastewater treatment workshop;

[0067] PO / SM wastewater containing organic peroxides, Wanhua Chemical Co., Ltd.;

[0068] Wastewater from acrylic acid plant containing formaldehyde, Wanhua Chemical Co., Ltd.;

[0069] GC analysis conditions: Agilent HP-5 gas chromatography column was used, the column size was 30m*530μm*1.5μm, and the column heating method was as follows: the initial temperature was set at 70°C, maintained for 5 min, and then heated to 300°C at a rate of 5°C / min, maintained for 10 min, and the main components of water quality were analyzed;

[0070] COD analysis: adopt national standard potassium dichromate oxidation analysis method.

[0071] In the following examples, the sampling and analysis results of wastewater containing organic peroxides are shown in Table 1.

[0072] Table 1 Composition of 1# wastewater

[0073]

[0074]

[0075] Table 2 Composition of 2# wastewater

[0076]

[0077]

[0078] Table 3 Composition of 3# wastewater

[0079]

[0080]

[0081]

[0082] Example 1

[0083] Preparation of 0# formaldehyde removal powder and evaluation of its combined treatment of POSM wastewater and formaldehyde wastewater.

[0084] 100g of wet sample of hydrometallurgical device was placed in an evaporating dish, mainly based on the total mass of waste from hydrometallurgical device after evaporation at 85℃: 22wt% of cobalt hydroxide, 15wt% of chromium hydroxide, 23wt% of polyaluminium chloride, 3wt% of polyacrylamide, 17wt% of activated carbon powder, 10wt% of phosphate kerosene, and 10wt% of calcium hydroxide. It was placed in an oven at 90℃ and dried for 5h. 20g of the dried sample was taken and ground with a small ball mill, and the particle size D50 was 5 microns.

[0085] The above 20g sample was uniformly mixed with 100g pure water, and stirred with magnetic stirring at a speed of 400rpm for 100min; heating was turned on at a temperature of 120°C and dried for 5h to obtain a pore-enlarged formaldehyde removal powder reagent, which contained 22.4wt% cobalt hydroxide, 15.3wt% chromium hydroxide, 23.5wt% polyaluminium chloride, 1wt% polyacrylamide, 17.7wt% activated carbon powder, 10.2wt% phosphate kerosene and 10.2wt% calcium hydroxide. Its bulk density was 1.23g / cm 3 , with a specific surface area of ​​110m 2 / g.

[0086] Take the POSM wastewater and formaldehyde wastewater shown in Table 1 and place them in a beaker, add 4.5g of 32wt% sodium hydroxide, adjust the pH to 10, add it to an intermittent reactor, adjust the reaction temperature to 50°C, the reaction time to 3h, add 2.8g of 0# powder, the formaldehyde content is reduced to 65mg / L, and the biochemical B / C is increased to 0.5.

[0087] Example 2

[0088] Preparation of 1# formaldehyde removal powder and evaluation of its combined treatment of POSM wastewater and formaldehyde wastewater.

[0089] 100g of wet sample of hydrometallurgical device was placed in an evaporating dish, mainly based on the total mass of waste from hydrometallurgical device after evaporation at 85℃: 20wt% cobalt hydroxide, 14wt% chromium hydroxide, 17wt% polyaluminium chloride, 12wt% polyacrylamide, 17wt% activated carbon powder, 10wt% phosphate kerosene, 10wt% calcium hydroxide. Place in an oven at 90℃ for 5h, take 20g of the dried sample, grind with a small ball mill, and the particle size D50 is 5 microns;

[0090] The above 20g sample was uniformly mixed with 100g pure water, and stirred with magnetic stirring at a speed of 400rpm for 100min; heating was turned on at a temperature of 120°C and dried for 5h to obtain a pore-enlarged formaldehyde removal powder reagent, which, based on the total mass of the whole powder, contained: 21.7wt% cobalt hydroxide, 15.2wt% chromium hydroxide, 18.5wt% polyaluminium chloride, 4.3wt% polyacrylamide, 18.5wt% activated carbon powder, 10.9wt% phosphate kerosene, and 10.9wt% calcium hydroxide. Its bulk density was 1.25g / cm 3 , with a specific surface area of ​​120m 2 / g.

[0091] Take the POSM wastewater and formaldehyde wastewater shown in Table 2 and place them in a beaker, add 4g of 32wt% sodium hydroxide, adjust the pH to 10.5, add it to an intermittent reactor, adjust the reaction temperature to 40°C, the reaction time to 2h, add 5g of 1# powder, the formaldehyde content is reduced to 37mg / L, and the biochemical B / C is increased to 0.55.

[0092] Example 3

[0093] Preparation of 2# formaldehyde removal powder and evaluation of its combined treatment of POSM wastewater and formaldehyde wastewater.

[0094] 100g of wet sample of hydrometallurgical device was placed in an evaporating dish, mainly based on the total mass of waste from hydrometallurgical device after evaporation at 85℃: 8wt% cobalt hydroxide, 20wt% chromium hydroxide, 21wt% polyaluminium chloride, 6wt% polyacrylamide, 25wt% activated carbon powder, 10wt% phosphate kerosene, and 10wt% calcium hydroxide. It was placed in an oven at 90℃ for 5h, and 20g of the dried sample was taken and ground with a small ball mill, with a particle size D50 of 5 microns;

[0095] The above 20g sample was uniformly mixed with 100g pure water, and stirred with magnetic stirring at a speed of 400rpm for 100min; heating was turned on at a temperature of 120°C and dried for 5h to obtain a pore-enlarged formaldehyde removal powder reagent, which contained 8.3wt% cobalt hydroxide, 20.8wt% chromium hydroxide, 21.9wt% polyaluminium chloride, 2.1wt% polyacrylamide, 26.0wt% activated carbon powder, 10.4wt% phosphate kerosene and 10.4wt% calcium hydroxide. Its bulk density was 1.25g / cm 3 , with a specific surface area of ​​115m 2 / g.

[0096] Take the POSM wastewater and formaldehyde wastewater shown in Table 1 and place them in a beaker, add 4.5g of 32wt% sodium hydroxide, adjust the pH to 10, add it to an intermittent reactor, adjust the reaction temperature to 50°C, the reaction time to 3h, add 2.8g of 2# powder, the formaldehyde content is reduced to 28.9mg / L, and the biochemical B / C is increased to 0.6.

[0097] Example 4

[0098] Preparation of 3# formaldehyde removal powder and evaluation of its combined treatment of POSM wastewater and formaldehyde wastewater.

[0099] 100g of wet sample of hydrometallurgical device was placed in an evaporating dish, mainly based on the total mass of waste from hydrometallurgical device after evaporation at 85°C: 22wt% of cobalt hydroxide, 10wt% of chromium hydroxide, 21wt% of polyaluminium chloride, 6wt% of polyacrylamide, 21wt% of activated carbon powder, 10wt% of phosphate kerosene, and 10wt% of calcium hydroxide. It was placed in an oven at 90°C for 5h, and 20g of the dried sample was taken and ground with a small ball mill, with a particle size D50 of 5 microns;

[0100] The above 20g sample was uniformly mixed with 100g pure water, and stirred with magnetic stirring at a speed of 400rpm for 100min; the heating was turned on at a temperature of 120°C and dried for 5h to obtain the expanded formaldehyde removal powder reagent, which contained 22.9wt% cobalt hydroxide, 10.4wt% chromium hydroxide, 21.9wt% polyaluminium chloride, 2.1wt% polyacrylamide, 21.9wt% activated carbon powder, 10.4wt% phosphate kerosene and 10.4wt% calcium hydroxide. Its bulk density was 1.26g / cm 3 , with a specific surface area of ​​120m 2 / g.

[0101] Take the POSM wastewater and formaldehyde wastewater shown in Table 3 and place them in a beaker, add 3g of 32wt% sodium hydroxide, adjust the pH to 9, add it to an intermittent reactor, adjust the reaction temperature to 55°C, the reaction time to 4.5h, add 9g of 3# powder, the formaldehyde content is reduced to 30.5mg / L, and the biochemical B / C is increased to 0.57.

[0102] Example 5

[0103] Preparation of 4# formaldehyde removal powder and evaluation of its combined treatment of POSM wastewater and formaldehyde wastewater.

[0104] 100g of wet sample of hydrometallurgical device was placed in an evaporating dish, mainly based on the total mass of waste from hydrometallurgical device after evaporation at 85℃: 20wt% cobalt hydroxide, 13wt% chromium hydroxide, 21wt% polyaluminium chloride, 6wt% polyacrylamide, 25wt% activated carbon powder, 5wt% phosphate kerosene, 10wt% calcium hydroxide. It was placed in an oven at 90℃ for 5h, and 20g of the dried sample was taken and ground with a small ball mill, with a particle size D50 of 5 microns.

[0105] The above 20g sample was uniformly mixed with 100g pure water, and stirred with magnetic stirring at a speed of 400rpm for 100min; heating was turned on at a temperature of 120°C and dried for 5h to obtain a pore-enlarged formaldehyde removal powder reagent, which contained 20.8wt% cobalt hydroxide, 13.5wt% chromium hydroxide, 21.9wt% polyaluminium chloride, 2.1wt% polyacrylamide, 26wt% activated carbon powder, 5.2wt% phosphate kerosene and 10.4wt% calcium hydroxide, based on the total mass of the whole powder. Its bulk density was 1.21g / cm 3 , with a specific surface area of ​​120m 2 / g.

[0106] Take the POSM wastewater and formaldehyde wastewater shown in Table 1 and place them in a beaker, add 4.5g of 32wt% sodium hydroxide, adjust the pH to 10, add it to an intermittent reactor, adjust the reaction temperature to 50°C, the reaction time to 3h, add 2.8g of 4# powder, the formaldehyde content is reduced to 34.5mg / L, and the biochemical B / C is increased to 0.6.

[0107] Example 6

[0108] Preparation of 5# formaldehyde removal powder and evaluation of its combined treatment of POSM wastewater and formaldehyde wastewater.

[0109] 100g of wet sample of hydrometallurgical device was placed in an evaporating dish, mainly based on the total mass of waste from hydrometallurgical device after evaporation at 85℃: 25wt% cobalt hydroxide, 15wt% chromium hydroxide, 21wt% polyaluminium chloride, 6wt% polyacrylamide, 25wt% activated carbon powder, 3wt% phosphate kerosene, 5wt% calcium hydroxide. Place in an oven at 90℃ for 5h, take 20g of the dried sample, grind it with a small ball mill, and the particle size D50 is 5 microns;

[0110] The above 20g sample was uniformly mixed with 100g pure water, and stirred with magnetic stirring at a speed of 400rpm for 100min; the heating was turned on at a temperature of 120℃ and dried for 5h to obtain the expanded formaldehyde removal powder reagent, which contained 26wt% cobalt hydroxide, 15.6wt% chromium hydroxide, 21.9wt% polyaluminium chloride, 2.1wt% polyacrylamide, 26wt% activated carbon powder, 3.1wt% phosphate kerosene and 5.2wt% calcium hydroxide. Its bulk density was 1.24g / cm 3 , with a specific surface area of ​​120m 2 / g.

[0111] Take the POSM wastewater and formaldehyde wastewater shown in Table 1 and place them in a beaker, add 4.5g of 32wt% sodium hydroxide, adjust the pH to 10, add it to an intermittent reactor, adjust the reaction temperature to 50°C, the reaction time to 3h, add 2.8g of 5# powder, the formaldehyde content is reduced to 40.5mg / L, and the biochemical B / C is increased to 0.55.

[0112] Comparative Example 1

[0113] Compared with Example 1, the difference is that polyacrylamide is removed.

[0114] Preparation of 6# formaldehyde removal powder and evaluation of its combined treatment of POSM wastewater and formaldehyde wastewater.

[0115] Take 100g of wet sample of hydrometallurgical device and place it in an evaporating dish. The total mass of waste from hydrometallurgical device after evaporation at 85℃ is mainly calculated as follows: 22wt% cobalt hydroxide, 15wt% chromium hydroxide, 23wt% polyaluminium chloride, 3wt% polyacrylamide, 17wt% activated carbon powder, 10wt% phosphate kerosene, and 10wt% calcium hydroxide. Mix the above raw materials with dichloromethane in a mass ratio of 1:1, place them in a glass beaker, and stir them fully with a glass rod for 10min. After stirring, use 5μm filter paper to vacuum filter the material to remove the extraction liquid, and mix the filtered filter material with pure water in a mass ratio of 1:1. Repeat the above extraction and filtration process for 2 consecutive times to obtain the filter material extracted with dichloromethane and washed with pure water. Place it in an oven at 90℃ and dry it for 5h. Take 20g of the dried sample and grind it with a small ball mill. The particle size D50 is 5 microns.

[0116] The above 20g sample was uniformly mixed with 100g pure water, and stirred with magnetic stirring at a speed of 400rpm for 100min; heating was turned on at a temperature of 120°C and dried for 5h to obtain a pore-enlarged formaldehyde removal powder reagent, which contained 25.8wt% cobalt hydroxide, 17.6wt% chromium hydroxide, 27wt% polyaluminium chloride, 0wt% polyacrylamide, 19.9wt% activated carbon powder, 0wt% phosphate kerosene and 11.7wt% calcium hydroxide. Its bulk density was 2.1g / cm 3 , with a specific surface area of ​​10m 2 / g.

[0117] Take the POSM wastewater and formaldehyde wastewater shown in Table 1 and place them in a beaker, add 4.5g of 32wt% sodium hydroxide, adjust the pH to 10, add it to an intermittent reactor, adjust the reaction temperature to 50°C, the reaction time to 3h, add 2.8g of 6# powder, the formaldehyde content is reduced to 7890mg / L, and the biochemical B / C is increased to 0.

Claims

1. A method for preparing a solid powder for treating formaldehyde-containing wastewater, characterized in that: The method comprises the following steps: S1: Waste from a hydrometallurgical plant is stirred and mixed with water to obtain a mixture; S2: treating the mixture at high temperature under stirring to obtain a target solid powder; Among them, the waste from the hydrometallurgical device described in S1 includes cobalt hydroxide, chromium hydroxide, polyaluminium chloride, polyacrylamide, activated carbon powder, phosphate kerosene and calcium hydroxide.

2. The preparation method according to claim 1, characterized in that: The composition of the waste from the hydrometallurgical unit in S1 is as follows, calculated based on the total mass of the waste after evaporation of water: Cobalt hydroxide 5-25wt%, preferably 15-22wt%, Chromium hydroxide 10-20wt%, preferably 12-15wt%, Polyaluminium chloride 11~25wt%, Polyacrylamide 3-12wt%, preferably 4-8wt%, Activated carbon powder 5~25wt%, Phosphate kerosene 3-10wt%, preferably 4-6wt%, Calcium hydroxide 2-10wt%, preferably 3-5wt%; And / or, the ratio of waste to water in S1 hydrometallurgical device is 1:(3-8), preferably 1:(4-6).

3. The preparation method according to claim 1 or 2, characterized in that: The temperature of high temperature treatment in S2 is 100-130°C; And / or, S2 is based on the weight of the solid powder, and the solid powder comprises the following components: Cobalt hydroxide 5.5-25.5wt%, preferably 15-22wt%, Chromium hydroxide 11-21wt%, preferably 13-16wt%, Polyaluminium chloride 12~27wt% Polyacrylamide 1-4wt%, preferably 1.2-2.5wt%, Activated carbon powder 6~28wt% Phosphate ester kerosene 3-12wt%, preferably 5-7wt%, Calcium hydroxide 3-12wt%, preferably 4-7wt%.

4. A solid powder for treating formaldehyde-containing wastewater, wherein the solid powder is prepared by the preparation method according to any one of claims 1 to 3, characterized in that: Based on the weight of the solid powder, the solid powder comprises the following components: Cobalt hydroxide 5.5-25.5wt%, preferably 15-22wt%, Chromium hydroxide 11-21wt%, preferably 13-16wt%, Polyaluminium chloride 12~27wt% Polyacrylamide 1-4wt%, preferably 1.2-2.5wt%, Activated carbon powder 6~28wt% Phosphate ester kerosene 3-12wt%, preferably 5-7wt%, Calcium hydroxide 3-12wt%, preferably 4-7wt%.

5. Use of a solid powder for treating formaldehyde-containing wastewater, the solid powder being the solid powder prepared by the preparation method according to any one of claims 1 to 3, or the solid powder according to claim 4, the solid powder being used for treating formaldehyde-containing wastewater, preferably for the combined treatment of peroxide-containing wastewater and formaldehyde-containing wastewater, more preferably for the combined treatment of PO / SM peroxide-containing wastewater and acrylic acid device formaldehyde-containing wastewater.

6. A method for jointly treating wastewater containing peroxide and wastewater containing formaldehyde, the method comprising the solid powder prepared by the preparation method according to any one of claims 1 to 3, or the solid powder according to claim 4, the method comprising the following steps: SS1: Wastewater containing peroxide and wastewater containing formaldehyde are mixed to obtain mixed wastewater; SS2: Adjust the pH value of mixed wastewater; SS3: The mixed wastewater enters the reactor, and the solid powder for treating the wastewater containing formaldehyde is added into the reactor for reaction; SS4: After the reaction is completed, the solid and liquid are separated, the solid is treated as hazardous waste, and the liquid meets the biochemical indicators and is discharged.

7. The method according to claim 6, characterized in that The total amount of peroxide in SS1, calculated as hydrogen peroxide, is higher than the formaldehyde content, calculated as mass per unit time; Preferably, the peroxide-containing wastewater in SS1 comes from a PO / SM device; Preferably, the organic peroxide content in the peroxide-containing wastewater of SS1 is ≤30000 mg / L, COD is ≤80000 mg / L, and preferably the methyl hydroperoxide content in the peroxide-containing wastewater is ≤25000 mg / L; Preferably, the formaldehyde-containing wastewater in SS1 comes from an acrylic acid plant; Preferably, the formaldehyde content in the formaldehyde-containing wastewater of SS1 is ≤40000 mg / L, and the COD is ≤50000 mg / L; and / or, adjusting the pH in SS2 with a base or an acid; and / or, adjusting the pH in SS2 to 9-11; and / or, a stirred tank reactor is used in SS3; and / or, the amount of solid powder added to SS3 is 5-10 g / L; and / or, SS3 reaction temperature 40-60°C, mixed wastewater, reaction time 2-5h; And / or, the formaldehyde content in the liquid after SS4 separation is ≤700mg / L, and COD is ≤38000mg / L.

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