A fly ash-based composite water treatment agent for complex harmful components in sewage

Abstract

The invention discloses a fly ash-based composite water treatment agent for complex harmful components in sewage, and relates to the technical field of sewage treatment. The fly ash-based composite water treatment agent for complex harmful components in sewage of the present invention, on the one hand, utilizes fly ash as industrial solid waste and uses it to prepare water treatment agent, which not only realizes the resource utilization of waste, reduces the land occupied by fly ash storage and potential pollution to the environment, but also greatly reduces the production cost of the water treatment agent. On the other hand, the components such as the modifier and composite oxidant used in the preparation process are mainly common chemical raw materials, which are relatively cheap, and the preparation process is simple and easy, does not require complex equipment and harsh reaction conditions, and is easy to mass produce, which makes the water treatment agent highly competitive in the market and can reduce the operating costs for sewage treatment companies.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, in particular to a fly ash-based composite water treatment agent for complex harmful components in sewage. Background Art

[0002] With the rapid development of industry and the acceleration of urbanization, the problem of sewage discharge is becoming increasingly serious. Sewage often contains a variety of complex harmful components, such as heavy metal ions such as lead, mercury, and cadmium, organic pollutants such as polycyclic aromatic hydrocarbons and phenolic compounds, and nitrogen and phosphorus nutrients. If these pollutants are directly discharged without effective treatment, they will pose a serious threat to the ecological environment.

[0003] At present, common sewage treatment methods include physical, chemical and biological methods. Although physical methods such as adsorption and filtration can remove some pollutants, they have limited effects on the removal of some soluble pollutants and complex harmful components; chemical methods such as coagulation and sedimentation can remove pollutants to a certain extent, but they often require the use of a large amount of chemical agents and are prone to secondary pollution; biological methods have a long treatment cycle, high requirements on water quality and environmental conditions, and poor treatment effects on some difficult-to-degrade organic pollutants and heavy metal ions.

[0004] Fly ash is the main solid waste discharged by coal-fired power plants. Its output is huge, and large-scale accumulation not only occupies land resources, but also pollutes the environment. However, fly ash contains a variety of active ingredients, such as silica, alumina, etc., which have certain adsorption and chemical reaction activities. Applying fly ash to sewage treatment can not only realize the resource utilization of solid waste, but also reduce the cost of sewage treatment. However, the current fly ash-based water treatment agents have the problem of not being accurate enough in removing complex harmful components in sewage and having low treatment efficiency. Therefore, the development of a fly ash-based composite water treatment agent that can remove complex harmful components in sewage has important practical significance. Summary of the Invention

[0005] The purpose of the present invention is to make up for the shortcomings of the existing technology and provide a fly ash-based composite water treatment agent for complex harmful components in sewage. It can realize the resource utilization of waste, reduce the land occupied by fly ash storage and potential pollution to the environment, and reduce the production cost of the water treatment agent. In addition, the modifiers, composite oxidants and other components used in the preparation process are mainly common chemical raw materials, which are relatively cheap. The preparation process is simple and easy, does not require complex equipment and harsh reaction conditions, and is easy to mass produce. This makes the water treatment agent highly competitive in the market, can reduce operating costs for sewage treatment companies, and at the same time provides an effective way to treat and utilize fly ash.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a fly ash-based composite water treatment agent for complex harmful components in sewage, the composite water treatment agent is composed of the following raw materials in the following mass percentages:

[0007] Fly ash: 30%-50%;

[0008] Modifier: 20%-30%;

[0009] Composite oxidant: 10%-20%;

[0010] Flocculant: 5%-15%;

[0011] Additives: 1%-5%;

[0012] The fly ash is pretreated, including grinding, screening, acid leaching and alkali washing, to remove impurities therein and activate its surface to improve its adsorption performance and reaction activity;

[0013] The modifier includes a complex of an organic acid, an inorganic salt, and a surfactant, which can react chemically and physically adsorb with the surface of the fly ash to form a composite material with a rich pore structure and multiple active sites, thereby enhancing its adsorption capacity for organic matter and heavy metal ions in sewage and its oxidation of ammonia nitrogen;

[0014] The composite oxidant can generate strong oxidizing free radicals during the water treatment process, undergo redox reactions with organic matter in the sewage, and decompose it into harmless small molecules. It can also oxidize some heavy metal ions in the sewage, making them easier to be adsorbed and removed by fly ash-based materials.

[0015] The flocculant is a mixture of polyaluminium ferric chloride and polyacrylamide, which can aggregate tiny particles and harmful substances that have been adsorbed and oxidized in sewage through electrostatic and bridging effects to form larger flocs, which are convenient for subsequent sedimentation and separation.

[0016] The auxiliary agent is a compound of a dispersant, a preservative and a pH regulator, which can improve the stability and service life of the water treatment agent and adjust the pH value of the sewage to a range that is conducive to the removal of harmful components.

[0017] Furthermore, the fly ash pretreatment process is as follows: calcining the fly ash at 600-800° C. for 2-4 hours, soaking it in a hydrochloric acid solution with a mass fraction of 5-10% for 1-3 hours, filtering it, washing it to neutrality, and drying it for later use.

[0018] Furthermore, the modifier is composed of the following components in percentage by mass:

[0019] Organic acid: 30%-50%;

[0020] Inorganic salt: 30%-40%;

[0021] Surfactant: 10%-20%;

[0022] The organic acid is one of citric acid, oxalic acid and malic acid;

[0023] The inorganic salt is one of ferrous sulfate, ferric chloride, and calcium nitrate;

[0024] The surfactant is one of sodium dodecylbenzenesulfonate and hexadecyltrimethylammonium bromide.

[0025] Furthermore, the composite oxidant is composed of the following components in percentage by mass:

[0026] Persulfate: 50%-70%;

[0027] Sulfite: 20%-30%;

[0028] Stabilizer: 5%-10%;

[0029] The stabilizer is one of magnesium sulfate and zinc sulfate.

[0030] Furthermore, the flocculant is composed of the following components in percentage by mass:

[0031] Polyaluminium ferric chloride: 60%-80%;

[0032] Polyacrylamide: 20%-40%;

[0033] The polyaluminium ferric chloride is a highly efficient inorganic polymer flocculant that can form a variety of complexes and colloidal particles with strong adsorption and netting capabilities during the hydrolysis process. Through electrostatic action and adsorption bridging action, it can aggregate the negatively charged colloidal particles and treated tiny harmful substances in the sewage to form larger flocs. Polyacrylamide is an organic polymer flocculant with a long-chain molecular structure. Its molecular chain contains a large number of active groups, which can interact with suspended matter, colloidal particles and harmful substances in the sewage through hydrogen bonds and van der Waals forces, further enhancing the strength and stability of the flocs and making the flocs easier to settle and separate.

[0034] Furthermore, the auxiliary agent is composed of the following components in percentage by mass:

[0035] Dispersant: 30%-50%;

[0036] Preservatives: 20%-30%;

[0037] pH adjuster: 20%-40%;

[0038] The dispersant is sodium polyacrylate;

[0039] The preservative is sodium benzoate;

[0040] The pH regulator is one of sodium hydroxide, sodium carbonate and hydrochloric acid;

[0041] The dispersant can reduce the tendency of fly ash-based composite water treatment agent particles to agglomerate, allowing the water treatment agent to be evenly dispersed in sewage, thereby increasing its contact area and reaction efficiency with complex harmful components in sewage. The preservative can inhibit the growth and reproduction of microorganisms during the storage and use of the water treatment agent, preventing the water treatment agent from deteriorating and becoming ineffective, thereby extending its service life. The pH regulator is used to adjust the acidity and alkalinity of sewage, thereby improving the water treatment agent's adsorption and removal effect on heavy metal ions.

[0042] Furthermore, the preparation steps of the composite water treatment agent are:

[0043] The fly ash is ground and sieved, and then subjected to acid leaching. The acid leaching liquid is a hydrochloric acid solution with a mass fraction of 10%-20%. The acid leaching temperature is 70℃-90℃, and the acid leaching time is 1-3 hours. After the acid leaching, it is filtered, washed and dried.

[0044] The fly ash after acid leaching is subjected to alkali washing treatment, the alkali washing liquid is 5%-15% by mass of sodium hydroxide, the alkali washing temperature is 60°C-80°C, the alkali washing time is 0.5-2 hours, and after the alkali washing, it is filtered, washed and dried again to obtain pretreated fly ash;

[0045] The pretreated fly ash is mixed with the modifier, heated to 80-120°C under stirring, and reacted for 2-4 hours to allow the modifier to fully contact the surface of the fly ash and undergo chemical reaction and physical adsorption to form modified fly ash;

[0046] The composite oxidant, flocculant and auxiliary agent are dissolved in deionized water to prepare a solution, the modified fly ash is dispersed in the solution, and mechanical stirring is performed to mix so that the components are evenly dispersed on the surface and pores of the modified fly ash;

[0047] The mixed slurry is dried at a temperature of 40° C. to 60° C. until the moisture content is less than 10%, and then crushed and sieved to obtain fly ash-based composite water treatment agent particles.

[0048] Furthermore, when the water treatment agent is used, the fly ash-based composite water treatment agent is added to the sewage at a dosage of 0.1g / L-1g / L according to the type and concentration of complex harmful components in the sewage, and mechanical stirring is performed to allow the water treatment agent and sewage to be fully mixed and contacted. The stirring time is 10-30 minutes, and then the water treatment agent is allowed to stand and settle for 30-60 minutes. The suspended matter and harmful components in the supernatant are removed by filtration and centrifugal separation to achieve the purpose of purifying the sewage.

[0049] Compared with the existing technology, this fly ash-based composite water treatment agent for complex harmful components in sewage has the following beneficial effects:

[0050] 1. The present invention provides a fly ash-based composite water treatment agent for complex harmful components in sewage. On the one hand, fly ash is used as industrial solid waste to prepare water treatment agents, which not only realizes the resource utilization of waste, reduces the land occupied by fly ash storage and potential pollution to the environment, but also greatly reduces the production cost of the water treatment agent. On the other hand, the modifiers, composite oxidants and other components used in the preparation process are mainly common chemical raw materials, which are relatively cheap, and the preparation process is simple and easy, without the need for complex equipment and harsh reaction conditions, and is easy to mass produce. This makes the water treatment agent highly competitive in the market, can reduce operating costs for sewage treatment companies, and at the same time provides an effective way to treat and utilize fly ash.

[0051] 2. The fly ash-based composite water treatment agent of the present invention has excellent multifunctional synergistic treatment performance. Through composite modification, a close synergistic mechanism is formed between fly ash and various components. The modifier can significantly improve the adsorption selectivity and adsorption amount of fly ash for heavy metal ions, while enhancing its adsorption capacity for organic matter; the composite oxidant can oxidize and decompose the difficult-to-degrade organic matter in sewage into small molecules that are easily biodegradable, and can also oxidize some heavy metal ions to turn them into high-valent states, which are more conducive to adsorption by fly ash; the flocculant helps to aggregate the tiny particles formed by the water treatment agent and harmful components in sewage into large flocs, which are convenient for sedimentation and separation. This multifunctional synergistic effect enables the water treatment agent to simultaneously and efficiently remove multiple complex harmful components in sewage.

[0052] Other advantages, objects and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be learned from the practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0054] Figure 1 The present invention is a flow chart for the preparation of a fly ash-based composite water treatment agent for complex harmful components in sewage. DETAILED DESCRIPTION

[0055] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0056] A fly ash-based composite water treatment agent for complex harmful components in sewage. The raw materials of the composite water treatment agent include: 30%-50% fly ash, 20%-30% modifier, 10%-20% composite oxidant, 5%-15% flocculant, and 1%-5% additive.

[0057] The fly ash is calcined at 600-800° C. for 2-4 hours, soaked in a hydrochloric acid solution with a mass fraction of 5-10% for 1-3 hours, filtered, washed to neutrality, and dried for standby use, so as to remove impurities therein and activate its surface to improve its adsorption performance and reaction activity.

[0058] The components of the modifier include: 30%-50% organic acid (citric acid, oxalic acid, malic acid), 30%-40% inorganic salt (ferrous sulfate, ferric chloride, calcium nitrate), and 10%-20% surfactant (sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide). The modifier can chemically react and physically adsorb with the surface of fly ash to form a composite material with a rich pore structure and multiple active sites, thereby enhancing its adsorption capacity for organic matter and heavy metal ions in sewage and its oxidation effect on ammonia nitrogen.

[0059] The composite oxidant comprises 50%-70% persulfate, 20%-30% sulfite, and 5%-10% stabilizer (such as magnesium sulfate and zinc sulfate). The composite oxidant can generate strong oxidizing free radicals during the water treatment process, undergo redox reactions with organic matter in the sewage, and decompose it into harmless small molecules. It can also oxidize some heavy metal ions in the sewage, making them easier to be adsorbed and removed by fly ash-based materials.

[0060] The flocculant is polyaluminum ferric chloride, polyacrylamide or a mixture of the two, which can aggregate tiny particles and harmful substances that have been adsorbed and oxidized in sewage through electrostatic and bridging effects to form larger flocs, which are convenient for subsequent sedimentation and separation.

[0061] The auxiliary agent is a compound of a dispersant, a preservative and a pH regulator, which can improve the stability and service life of the water treatment agent and adjust the pH value of the sewage to a range that is conducive to the removal of harmful components.

[0062] like Figure 1 As shown, the composite water treatment agent is prepared, and the preparation steps are as follows:

[0063] S100, after grinding and screening the fly ash, subjecting it to acid leaching treatment, wherein the acid leaching liquid is 10%-20% hydrochloric acid, the acid leaching temperature is 70°C-90°C, the acid leaching time is 1-3 hours, and after the acid leaching is completed, filtering, washing and drying are performed;

[0064] S200, performing alkali washing on the fly ash after acid leaching, wherein the alkali washing liquid is a sodium hydroxide or potassium hydroxide solution with a mass fraction of 5%-15%, the alkali washing temperature is 60° C.-80° C., and the alkali washing time is 0.5-2 hours. After the alkali washing is completed, filtering, washing and drying are performed again to obtain pretreated fly ash;

[0065] S300, mixing the pretreated fly ash and the modifier in proportion, heating to 80° C.-120° C. under stirring, and reacting for 2-4 hours, so that the modifier fully contacts the surface of the fly ash and undergoes chemical reaction and physical adsorption, thereby forming modified fly ash;

[0066] S400, dissolving the composite oxidant, flocculant and additive in appropriate amounts of deionized water to prepare solutions of a certain concentration, then dispersing the modified fly ash in these solutions, and mechanically stirring and mixing them to uniformly disperse the components on the surface and in the pores of the modified fly ash;

[0067] S500, drying the mixed slurry at a drying temperature of 40°C-60°C until the moisture content is less than 10%, and then crushing and sieving to obtain fly ash-based composite water treatment agent particles with a particle size of less than 150 μm.

[0068] Example 1

[0069] Raw material preparation

[0070] Fly ash: Take 40% of the fly ash from coal-fired power plants, grind it first, then calcine it at 700℃ for 3 hours, then soak it in 8% hydrochloric acid solution for 2 hours, filter it, wash it to neutrality, and dry it for later use.

[0071] Modifier: Take 25%, of which organic acid (citric acid) accounts for 40%, inorganic salt (ferrous sulfate) accounts for 35%, and surfactant (sodium dodecylbenzene sulfonate) accounts for 25%.

[0072] Composite oxidant: 15%, persulfate (potassium persulfate) accounts for 60%, sulfite (sodium sulfite) accounts for 25%, and stabilizer (magnesium sulfate) accounts for 15%.

[0073] Flocculant: 10%, polyaluminium ferric chloride 70%, polyacrylamide 30%.

[0074] Additives: 5%, dispersant (sodium polyacrylate) accounts for 40%, preservative (sodium benzoate) accounts for 25%, pH adjuster (sodium hydroxide) accounts for 35%.

[0075] Preparation process

[0076] The fly ash was acid-leached with a 15% by mass hydrochloric acid solution at 80°C for 2 hours, filtered, washed and dried.

[0077] The fly ash after acid leaching was alkali washed with a 10% by mass sodium hydroxide solution at 70° C. for 1 hour, and then filtered, washed and dried again to obtain pretreated fly ash.

[0078] The pretreated fly ash is mixed with the modifier, heated to 100° C. under stirring, and reacted for 3 hours to form modified fly ash.

[0079] The composite oxidant, flocculant and auxiliary agent are respectively dissolved in deionized water to prepare a solution, the modified fly ash is dispersed in the solution, and the solution is mechanically stirred and mixed.

[0080] The mixed slurry is dried at 50° C. until the moisture content is less than 10%, and then crushed and sieved to obtain fly ash-based composite water treatment agent particles.

[0081] Usage: For simulated sewage containing lead ions (50 mg / L), phenolic compounds (80 mg / L), and ammonia nitrogen (40 mg / L), add the water treatment agent to the sewage at a dosage of 0.5 g / L, mechanically stir for 20 minutes, let it settle for 45 minutes, filter and centrifuge to remove suspended matter and harmful components in the supernatant.

[0082] Implementation effect: After testing, after using the water treatment agent of this embodiment to treat simulated sewage, the lead ion removal rate reached 95%, and the lead ion concentration after treatment dropped from 50 mg / L to 2.5 mg / L; the phenol compound removal rate was 90%, and the concentration dropped from 80 mg / L to 8 mg / L; the ammonia nitrogen removal rate was 88%, and the concentration dropped from 40 mg / L to 4.8 mg / L. The treated sewage was clear and odorless and could be directly discharged or subjected to subsequent deep treatment and reuse. This shows that the water treatment agent is effective in removing lead ions, phenol compounds and ammonia nitrogen, and can effectively purify sewage.

[0083] Example 2

[0084] Raw material preparation

[0085] Fly ash: Take 30%, grind it and calcine it at 600℃ for 2 hours, soak it in 5% hydrochloric acid solution for 1 hour, filter, wash and dry it.

[0086] Modifier: 30%, organic acid (oxalic acid) accounts for 30%, inorganic salt (ferric chloride) accounts for 40%, and surfactant (hexadecyltrimethylammonium bromide) accounts for 30%.

[0087] Composite oxidant: 20%, persulfate (sodium persulfate) accounts for 70%, sulfite (potassium sulfite) accounts for 20%, and stabilizer (zinc sulfate) accounts for 10%.

[0088] Flocculant: 15%, polyaluminium ferric chloride 80%, polyacrylamide 20%.

[0089] Additives: 5%, dispersant (sodium polyacrylate) accounts for 50%, preservative (sodium benzoate) accounts for 20%, pH adjuster (sodium carbonate) accounts for 30%.

[0090] Preparation process

[0091] Acid leaching: acid leaching with a 10% by mass hydrochloric acid solution at 70° C. for 1 hour, and subsequent treatment is the same as in Example 1.

[0092] Alkali washing: using a 5% by mass sodium hydroxide solution at 60° C. for 0.5 hour, and the subsequent treatment is the same as in Example 1.

[0093] Modification: Heat to 80℃ with the modifier under stirring and react for 4 hours.

[0094] Mixing and drying: same as in Example 1.

[0095] Usage: For simulated sewage containing mercury ions (20 mg / L), polycyclic aromatic hydrocarbons (60 mg / L), and total phosphorus (30 mg / L), the dosage is 0.8 g / L, stirred for 15 minutes, and settled for 50 minutes. The subsequent treatment is the same as in Example 1.

[0096] Implementation effect: The water treatment agent of Example 2 has significant treatment effect on simulated sewage, with a mercury ion removal rate of up to 88%. After treatment, its concentration dropped from 20 mg / L to 2.4 mg / L; the polycyclic aromatic hydrocarbons removal rate is 85%, and the concentration dropped from 60 mg / L to 9 mg / L; the total phosphorus removal rate is 82%, and the concentration dropped from 30 mg / L to 5.4 mg / L. The water quality of the treated sewage is significantly improved, the water transparency is greatly improved, and there are no visible impurities. This proves that the water treatment agent has outstanding removal ability for mercury ions, polycyclic aromatic hydrocarbons and total phosphorus, and can efficiently treat sewage containing such complex harmful components.

[0097] Example 3

[0098] Raw material preparation

[0099] Fly ash: Take 50% fly ash from local power plants, grind it and calcine it at 800℃ for 4 hours, soak it in 10% hydrochloric acid solution for 3 hours, filter, wash and dry it.

[0100] Modifier: 20%, organic acid (malic acid) accounts for 50%, inorganic salt (calcium nitrate) accounts for 30%, and surfactant (sodium dodecylbenzene sulfonate) accounts for 20%.

[0101] Composite oxidant: 10%, persulfate (ammonium persulfate) 50%, sulfite (sodium sulfite) 30%, stabilizer (magnesium sulfate) 20%.

[0102] Flocculant: 15%, polyaluminium ferric chloride 60%, polyacrylamide 40%.

[0103] Additives: 5%, dispersant (sodium polyacrylate) accounts for 30%, preservative (sodium benzoate) accounts for 30%, pH adjuster (hydrochloric acid) accounts for 40%.

[0104] Preparation process

[0105] Acid leaching: Use 20% mass fraction hydrochloric acid solution to acid leaching at 90℃ for 3 hours.

[0106] Alkali washing: Use 15% mass fraction sodium hydroxide solution at 80℃ for 2 hours.

[0107] Modification: Heat to 120°C with stirring and react for 2 hours.

[0108] Mixing and drying: same as in Example 1.

[0109] Usage: Treat simulated sewage containing cadmium ions (30 mg / L), phenolic compounds (100 mg / L), and ammonia nitrogen (50 mg / L) with a dosage of 1 g / L, stir for 30 minutes, and settle for 60 minutes. Subsequent treatment is the same as in Example 1.

[0110] Implementation effect: When treating simulated sewage containing cadmium ions, phenolic compounds and ammonia nitrogen, the water treatment agent of Example 3 performed excellently, with a cadmium ion removal rate of 98%, and the concentration after treatment dropped from 30 mg / L to 0.6 mg / L; the phenolic compound removal rate was 92%, and the concentration dropped from 100 mg / L to 8 mg / L; the ammonia nitrogen removal rate was 90%, and the concentration dropped from 50 mg / L to 5 mg / L. The treated sewage has excellent water quality and can meet the needs of various water use scenarios. This fully demonstrates that the water treatment agent can accurately and efficiently remove complex harmful components in sewage.

[0111] Example 4

[0112] Raw material preparation

[0113] Fly ash: 35% is used. The pretreatment is the same as in Example 1, but the calcination temperature is 650°C.

[0114] Modifier: 28%, organic acid (citric acid) accounts for 45%, inorganic salt (ferrous sulfate) accounts for 32%, and surfactant (hexadecyltrimethylammonium bromide) accounts for 23%.

[0115] Composite oxidant: 16%, persulfate (potassium persulfate) accounts for 65%, sulfite (potassium sulfite) accounts for 22%, and stabilizer (zinc sulfate) accounts for 13%.

[0116] Flocculant: 10%, polyaluminium ferric chloride 75%, polyacrylamide 25%.

[0117] Additives: 1%, dispersant (sodium polyacrylate) accounts for 45%, preservative (sodium benzoate) accounts for 25%, pH adjuster (sodium hydroxide) accounts for 30%.

[0118] Preparation process

[0119] Acid leaching: Use 12% mass fraction hydrochloric acid solution to acid leaching at 75℃ for 1.5 hours.

[0120] Alkali washing: Use 8% by mass sodium hydroxide solution at 65°C for 1.2 hours.

[0121] Modification: Heat to 90°C with stirring and react for 3.5 hours.

[0122] Mixing and drying: same as in Example 1.

[0123] Usage: For simulated sewage containing lead ions (40 mg / L), polycyclic aromatic hydrocarbons (70 mg / L), and total phosphorus (25 mg / L), add 0.6 g / L, stir for 25 minutes, and settle for 40 minutes. Subsequent treatment is the same as in Example 1.

[0124] Implementation effect: The water treatment agent of Example 4 has a good effect on removing lead ions, polycyclic aromatic hydrocarbons and total phosphorus in simulated sewage. The lead ion removal rate is 96%, and the concentration after treatment is reduced from 40 mg / L to 1.6 mg / L; the polycyclic aromatic hydrocarbon removal rate is 87%, and the concentration is reduced from 70 mg / L to 9.1 mg / L; the total phosphorus removal rate is 81.25%, and the concentration is reduced from 25 mg / L to 4.75 mg / L, indicating that the water treatment agent has high reliability and stability in removing multiple complex harmful components.

[0125] Example 5

[0126] Raw material preparation

[0127] Fly ash: 45% is used. The pretreatment is the same as in Example 2, but the calcination time is 3.5 hours.

[0128] Modifier: 22%, organic acid (malic acid) accounts for 42%, inorganic salt (ferric chloride) accounts for 38%, and surfactant (sodium dodecylbenzene sulfonate) accounts for 20%.

[0129] Composite oxidant: 13%, persulfate (sodium persulfate) accounts for 55%, sulfite (sodium sulfite) accounts for 28%, and stabilizer (magnesium sulfate) accounts for 17%.

[0130] Flocculant: 15%, polyaluminium ferric chloride accounts for 72%, and polyacrylamide accounts for 28%.

[0131] Additives: 5%, dispersant (sodium polyacrylate) accounts for 40%, preservative (sodium benzoate) accounts for 28%, pH adjuster (sodium carbonate) accounts for 32%.

[0132] Preparation process

[0133] Acid leaching: Use 18% mass fraction hydrochloric acid solution to acid leaching at 85℃ for 2.5 hours.

[0134] Alkali washing: Use 12% mass fraction sodium hydroxide solution at 75℃ for 1.5 hours.

[0135] Modification: Heat to 110°C with stirring and react for 2.5 hours.

[0136] Mixing and drying: same as in Example 1.

[0137] Usage: Treat simulated sewage containing mercury ions (15 mg / L), phenolic compounds (90 mg / L), and ammonia nitrogen (45 mg / L) with a dosage of 0.7 g / L, stir for 18 minutes, and settle for 55 minutes. Subsequent treatment is the same as in Example 1.

[0138] Implementation effect: After using the water treatment agent of Example 5 to treat the simulated sewage, the mercury ion removal rate was 90%, and the concentration dropped from 15 mg / L to 1.5 mg / L; the phenolic compound removal rate was 90%, and the concentration dropped from 90 mg / L to 9 mg / L; the ammonia nitrogen removal rate was 89%, and the concentration dropped from 45 mg / L to 4.95 mg / . The water quality of the treated sewage was stable, indicating that the water treatment agent of this embodiment has an ideal effect on removing mercury ions, phenolic compounds and ammonia nitrogen in sewage, and can effectively improve the water quality of sewage.

[0139] Comparative Example 1

[0140] Raw materials preparation:

[0141] Fly ash: take 50%, and the processing method is the same as Example 3.

[0142] Composite oxidant: 20%; the composition is the same as that in Example 3.

[0143] Flocculant: 20%; the composition is the same as that in Example 3.

[0144] Additive: 10%, the composition is the same as that in Example 3.

[0145] Preparation process

[0146] The fly ash pretreatment is the same as in Example 3.

[0147] The pretreated fly ash is directly mixed with a solution of a composite oxidant, a flocculant and an additive, and mechanically stirred without using a modifier.

[0148] The drying, crushing and screening were the same as in Example 1.

[0149] Usage: Treat simulated sewage containing lead ions (50 mg / L), phenolic compounds (80 mg / L), and ammonia nitrogen (40 mg / L) with a dosage of 0.5 g / L, stir for 20 minutes, settle for 45 minutes, filter, and centrifuge.

[0150] Implementation effect: Due to the lack of modifier, the comparative example 1 did not perform well in treating simulated sewage. The lead ion removal rate was only 70%, and the concentration after treatment was 15 mg / L; the phenolic compound removal rate was 75%, and the concentration was 20 mg / L; the ammonia nitrogen removal rate was 70%, and the concentration was 12 mg / L. The treated sewage still contained a large amount of harmful components, and the water quality was turbid, indicating that the modifier plays a key role in enhancing the removal ability of water treatment agents for complex harmful components. The lack of modifier will seriously affect the treatment effect.

[0151] Comparative Example 2

[0152] Raw material preparation

[0153] Fly ash: take 40%, and the processing method is the same as Example 1.

[0154] Modifier: 30%, the composition is the same as that in Example 1.

[0155] Flocculant: 20%; the composition is the same as in Example 1.

[0156] Additive: 10%, the composition is the same as that in Example 1.

[0157] Preparation process

[0158] The fly ash pretreatment and modification are the same as in Example 1.

[0159] The modified fly ash is mixed with a solution of a flocculant and an additive, and mechanically stirred without using a composite oxidant.

[0160] The drying, crushing and screening were the same as in Example 1.

[0161] Usage: Treat simulated sewage containing mercury ions (20 mg / L), polycyclic aromatic hydrocarbons (60 mg / L), and total phosphorus (30 mg / L) with a dosage of 0.8 g / L, stir for 15 minutes, settle for 50 minutes, filter, and centrifuge.

[0162] Implementation effect: In comparative example 2, no composite oxidant was used. After treating the simulated sewage, the mercury ion removal rate was 75%, and the concentration after treatment was 5 mg / L; the polycyclic aromatic hydrocarbons removal rate was 70%, and the concentration was 18 mg / L; the total phosphorus removal rate was 75%, and the concentration was 7.5 mg / L. The content of organic pollutants and some heavy metal ions in the treated sewage was high, and the water quality was not effectively purified. This shows that composite oxidants are crucial for the efficient removal of organic pollutants and some heavy metal ions in sewage. The lack of composite oxidants will greatly reduce the treatment effect of the water treatment agent.

[0163] The above examples and comparative examples have different effects on the simulated sewage. Different components have different effects on the water treatment agents. Further, the raw material ratios of the examples and comparative examples are shown in Table 1 below:

[0164]

[0165] In summary, in this study of fly ash-based composite water treatment agents, the treatment effects of complex harmful components in sewage were comprehensively tested through multiple embodiments and comparative examples. Examples 1 to 5 demonstrated excellent treatment capabilities, and the removal rates of heavy metal ions such as lead, mercury, and cadmium, organic pollutants such as polycyclic aromatic hydrocarbons and phenolic compounds, and nutrients such as ammonia nitrogen and total phosphorus in different simulated sewage were relatively high. This shows that under reasonable raw material ratios and preparation processes, the water treatment agent can accurately and efficiently remove a variety of complex harmful components, effectively purify sewage, and meet the water quality requirements of different scenarios. In sharp contrast, comparative examples 1 and 2 lack a modifier, and the removal rate of lead ions, phenolic compounds, and ammonia nitrogen is significantly lower than that of the embodiment; comparative example 2 does not use a composite oxidant, and the removal effect of mercury ions, polycyclic aromatic hydrocarbons, and total phosphorus is greatly reduced. The treated sewage still contains a large number of harmful components, which fully demonstrates the key role of modifiers and composite oxidants in enhancing the ability of water treatment agents to remove complex harmful components.

[0166] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A fly ash-based composite water treatment agent for complex harmful components in sewage, characterized in that: The composite water treatment agent is composed of the following raw materials in percentage by mass: composition: Fly ash: 30%-50%; Modifier: 20%-30%; Composite oxidant: 10%-20%; Flocculant: 5%-15%; Additives: 1%-5%; The fly ash is pretreated, including grinding, screening, acid leaching and alkali washing, to remove impurities therein and activate its surface; The modifier includes a complex of organic acid, inorganic salt and surfactant, which adsorbs organic matter and heavy metal ions in sewage and oxidizes ammonia nitrogen; The composite oxidant undergoes an oxidation-reduction reaction with organic matter in the sewage, decomposing it into harmless small molecules and simultaneously oxidizing heavy metal ions in the sewage; The flocculant is a mixture of polyaluminium ferric chloride and polyacrylamide, which is used to aggregate the tiny particles and harmful substances that have been adsorbed and oxidized in the sewage to facilitate sedimentation and separation; The auxiliary agent is a compound of a dispersant, a preservative and a pH regulator, and is used to adjust the pH value of sewage; The fly ash pretreatment process is as follows: calcining the fly ash at 600-800° C. for 2-4 hours, soaking it in a hydrochloric acid solution with a mass fraction of 5-10% for 1-3 hours, filtering it, washing it to neutrality, and drying it for later use.

2. The fly ash-based composite water treatment agent for complex harmful components in sewage according to claim 1, characterized in that: The modifier is composed of the following components in percentage by mass: composition: Organic acid: 30%-50%; Inorganic salt: 30%-40%; Surfactant: 10%-20%; The organic acid is one of citric acid, oxalic acid and malic acid; The inorganic salt is one of ferrous sulfate, ferric chloride, and calcium nitrate; The surfactant is one of sodium dodecylbenzenesulfonate and hexadecyltrimethylammonium bromide.

3. The fly ash-based composite water treatment agent for complex harmful components in sewage according to claim 1, characterized in that: The composite oxidant is composed of the following components in percentage by mass: Persulfate: 50%-70%; Sulfite: 20%-30%; Stabilizer: 5%-10%; The stabilizer is one of magnesium sulfate and zinc sulfate.

4. The fly ash-based composite water treatment agent for complex harmful components in sewage according to claim 1, characterized in that: The flocculant is composed of the following components in percentage by mass: Polyaluminium ferric chloride: 60%-80%; Polyacrylamide: 20%-40%.

5. The fly ash-based composite water treatment agent for complex harmful components in sewage according to claim 1, characterized in that: The auxiliary agent is composed of the following components in percentage by mass: composition: Dispersant: 30%-50%; Preservatives: 20%-30%; pH adjuster: 20%-40%; The dispersant is sodium polyacrylate; The preservative is sodium benzoate; The pH regulator is one of sodium hydroxide, sodium carbonate and hydrochloric acid.

6. A fly ash-based composite water treatment agent for complex harmful components in sewage according to any one of claims 1 to 5, characterized in that: The preparation steps of the composite water treatment agent are: The fly ash is ground and sieved, and then subjected to acid leaching. The acid leaching liquid is a hydrochloric acid solution with a mass fraction of 10%-20%. The acid leaching temperature is 70℃-90℃, and the acid leaching time is 1-3 hours. After the acid leaching, it is filtered, washed and dried. The fly ash after acid leaching is subjected to alkali washing treatment, the alkali washing liquid is 5%-15% by mass of sodium hydroxide, the alkali washing temperature is 60°C-80°C, the alkali washing time is 0.5-2 hours, and after the alkali washing, it is filtered, washed and dried again to obtain pretreated fly ash; The pretreated fly ash is mixed with the modifier, heated to 80-120°C under stirring, and reacted for 2-4 hours to allow the modifier to fully contact the surface of the fly ash and undergo chemical reaction and physical adsorption to form modified fly ash; The composite oxidant, flocculant and auxiliary agent are dissolved in deionized water to prepare a solution, the modified fly ash is dispersed in the solution, and mechanical stirring is performed to mix so that the components are evenly dispersed on the surface and pores of the modified fly ash; The mixed slurry is dried at a temperature of 40° C. to 60° C. until the moisture content is less than 10%, and then crushed and sieved to obtain fly ash-based composite water treatment agent particles.

7. The fly ash-based composite water treatment agent for complex harmful components in sewage according to claim 6, characterized in that: When using the water treatment agent, the fly ash-based composite water treatment agent is added to the sewage at a dosage of 0.1g / L-1g / L according to the types and concentrations of complex harmful components in the sewage, and mechanical stirring is performed to ensure that the water treatment agent and the sewage are fully mixed and contacted. The stirring time is 10-30 minutes, and the mixture is allowed to stand and settle for 30-60 minutes. The suspended matter and harmful components in the supernatant are removed by filtration and centrifugal separation to achieve the purpose of purifying the sewage.

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