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 aiming at complex harmful components in sewage, and relates to the technical field of sewage treatment.The fly ash-based composite water treatment agent aiming at the complex harmful components in the sewage is characterized in that on one hand, fly ash is used as industrial solid waste and is used for preparing the water treatment agent; on the one hand, resource utilization of waste is achieved, the occupied area of coal ash stockpiling and potential pollution to the environment are reduced, the production cost of the water treatment agent is greatly reduced, on the other hand, the modifier, the composite oxidizing agent and other components used in the preparation process are mainly common chemical raw materials, the price is relatively low, the preparation process is simple and easy to implement, and the method is suitable for industrial production. The preparation method is simple, does not need complex equipment and harsh reaction conditions, and is easy for large-scale production, so that the water treatment agent has relatively strong competitiveness in the market, and the operation cost can be reduced for sewage treatment enterprises.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and specifically to a fly ash-based composite water treatment agent for complex and 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 severe. Sewage often contains various complex and harmful components, such as heavy metal ions like lead, mercury, cadmium, organic pollutants like 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. Currently, common sewage treatment methods include physical methods, chemical methods, and biological methods, etc. Physical methods such as adsorption and filtration can remove some pollutants, but their removal effects on some dissolved pollutants and complex and harmful components are limited; chemical methods such as coagulation and precipitation can remove pollutants to a certain extent, but 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 for water quality and environmental conditions, and poor treatment effects on some refractory organic pollutants and heavy metal ions. Fly ash is the main solid waste discharged from coal-fired power plants. Its output is huge. A large amount of stacking not only occupies land resources but also pollutes the environment. However, fly ash contains various active components such as silicon dioxide and alumina, and has 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 problems such as inaccurate removal of complex and harmful components in sewage and low treatment efficiency. Therefore, it is of great practical significance to develop a fly ash-based composite water treatment agent that can remove complex and harmful components in sewage. Summary of the Invention

[0003] The purpose of the present invention is to make up for the deficiencies of the existing technology and provide a fly ash-based composite water treatment agent for complex and harmful components in sewage. It can realize the resource utilization of waste, reduce the land occupation of fly ash storage and potential environmental pollution, reduce the production cost of the water treatment agent, and moreover, the components such as modifiers and composite oxidants used in the preparation process are mainly common chemical raw materials, with relatively low prices, and the preparation process is simple and easy to operate, without the need for complex equipment and harsh reaction conditions, and is easy to scale up production. This makes the water treatment agent highly competitive in the market, can reduce the operating cost for sewage treatment enterprises, and at the same time provides an effective way for the treatment and utilization of fly ash.

[0004] 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, and the composite water treatment agent is composed of the following raw materials in mass percentages: Fly ash: 30% - 50%; Modifier: 20% - 30%; Composite oxidant: 10% - 20%; Flocculant: 5% - 15%; Auxiliary agent: 1% - 5%; The fly ash is pretreated, including grinding, screening, acid leaching and alkali washing, to remove impurities therein and activate its surface, improving its adsorption performance and reaction activity; The modifier includes a composite of organic acid, inorganic salt and surfactant. The modifier can undergo chemical reactions and physical adsorption with the fly ash surface to form a composite material with a rich pore structure and various active sites, enhancing its adsorption capacity for organic matter and heavy metal ions in sewage and its oxidation effect on ammonia nitrogen; The composite oxidant can generate strongly oxidizing free radicals during the water treatment process, undergo redox reactions with organic matter in the sewage, decompose it into harmless small molecule substances, and at the same time can also oxidize some heavy metal ions in the sewage, making them more easily adsorbed and removed by the fly ash-based material; The flocculant is a mixture of polyaluminum ferric chloride and polyacrylamide, which can aggregate the tiny particles and harmful substances that have been adsorbed and oxidized in the sewage through electrostatic action and bridging action to form larger flocs, facilitating subsequent sedimentation and separation; The auxiliary agent is a composite of dispersant, preservative and pH regulator, which can improve the stability and service life of the water treatment agent, and at the same time adjust the pH value of the sewage to a range conducive to the removal of harmful components.

[0005] Further, the pretreatment process of the fly ash is: calcine the fly ash at 600 - 800 °C for 2 - 4 hours, soak it in a hydrochloric acid solution with a mass fraction of 5 - 10% for 1 - 3 hours, filter, wash until neutral, and dry for standby.

[0006] Furthermore, the modifier is composed of the following components in mass percentages: 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 dodecylbenzene sulfonate and hexadecyltrimethylammonium bromide.

[0007] Furthermore, 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.

[0008] Furthermore, the flocculant is composed of the following components in percentage by mass: Polyaluminium ferric chloride: 60%-80%; Polyacrylamide: 20%-40%; The polyaluminium ferric chloride is a highly efficient inorganic polymer flocculant, which can form a variety of complexes and colloidal particles with strong adsorption and net-catching capabilities during the hydrolysis process, and can aggregate the negatively charged colloidal particles and the treated tiny harmful substances in the sewage through electrostatic action and adsorption bridging action to form larger flocs. Polyacrylamide is an organic polymer flocculant with a long-chain molecular structure, which contains a large number of active groups on its molecular chain and 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.

[0009] Furthermore, the auxiliary agent is composed of the following components in percentage by mass: Dispersant: 30%-50%; Preservatives: 20%-30%; pH adjuster: 20%-40%; The dispersant is sodium polyacrylate; The preservative is sodium benzoate; The pH adjuster is one of sodium hydroxide, sodium carbonate and hydrochloric acid; The dispersant can reduce the agglomeration tendency between the particles of the fly ash-based composite water treatment agent, so that the water treatment agent can be evenly dispersed in the sewage, and its contact area and reaction efficiency with the complex harmful components in the sewage are increased. The preservative can inhibit the growth and reproduction of microorganisms in the water treatment agent during storage and use, prevent the water treatment agent from deteriorating and becoming ineffective, and extend its service life. The pH regulator is used to adjust the pH of the sewage, thereby improving the adsorption and removal effect of the water treatment agent on heavy metal ions.

[0010] Furthermore, the preparation steps of the composite water treatment agent are: The fly ash is ground and screened, and then subjected to acid leaching treatment. The acid leaching solution is a hydrochloric acid solution with a mass fraction of 10%-20%. The acid leaching temperature is 70°C - 90°C, and the acid leaching time is 1 - 3 hours. After the acid leaching is completed, filtration, washing, and drying are carried out. The acid-leached fly ash is subjected to alkali washing treatment. The alkali washing solution is sodium hydroxide 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, filtration, washing, and drying are carried out again to obtain the pretreated fly ash. The pretreated fly ash is mixed with a modifier, and heated to 80°C - 120°C under stirring for 2 - 4 hours, so that the modifier can fully contact the surface of the fly ash and undergo chemical reactions and physical adsorption, forming modified fly ash. The composite oxidant, flocculant, and auxiliary agent are respectively dissolved in deionized water to prepare solutions. The modified fly ash is dispersed in the solutions, and mechanical stirring and mixing are carried out to make each component evenly dispersed on the surface and in the pores of the modified fly ash. The mixed slurry is subjected to drying treatment. The drying temperature is 40°C - 60°C, and it is dried until the moisture content is lower than 10%. Then, it is crushed and screened to obtain fly ash-based composite water treatment agent particles.

[0011] Furthermore, when using the water treatment agent, according to the types and concentrations of complex and harmful components in the sewage, the fly ash-based composite water treatment agent is added to the sewage at a dosage of 0.1 g / L - 1 g / L, and mechanical stirring is carried out to make the water treatment agent fully mixed and contacted with the sewage. The stirring time is 10 - 30 minutes, and then static sedimentation is carried out. The sedimentation time is 30 - 60 minutes. The suspended substances and harmful components in the supernatant are removed by filtration and centrifugal separation, achieving the purpose of purifying the sewage.

[0012] Compared with the prior art, the fly ash-based composite water treatment agent for complex and harmful components in sewage has the following beneficial effects: First, for the fly ash-based composite water treatment agent for complex and harmful components in sewage of the present invention, on the one hand, using fly ash as an industrial solid waste to prepare a water treatment agent not only realizes the resource utilization of waste, reduces the land occupation of fly ash storage and potential environmental pollution, 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, with relatively low prices, and the preparation process is simple and easy to implement, without the need for complex equipment and harsh reaction conditions, and is easy to scale up production. This makes the water treatment agent highly competitive in the market, capable of reducing the operating costs of sewage treatment enterprises, and at the same time providing an effective way for the treatment and utilization of fly ash.

[0013] Second, the fly ash-based composite water treatment agent of the present invention has excellent multi-functional synergistic treatment performance. Through composite modification, a tight synergistic mechanism is formed between fly ash and each component. The modifier can significantly improve the adsorption selectivity and adsorption capacity of fly ash for heavy metal ions, and at the same time enhance its adsorption capacity for organic matter; the composite oxidant can oxidize and decompose the refractory organic matter in the sewage into small biodegradable molecules, and can also oxidize some heavy metal ions to make them into high-valent states, which is more conducive to being adsorbed by fly ash; the flocculant helps to aggregate the fine particles formed by the water treatment agent and the harmful components in the sewage into large flocs, facilitating sedimentation and separation. This multi-functional synergistic effect enables the water treatment agent to efficiently remove various complex harmful components in the sewage at the same time.

[0014] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0016] Figure 1 It is a preparation flow chart of a fly ash-based composite water treatment agent for complex harmful components in sewage. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention objective, the following will, in conjunction with the accompanying drawings and preferred embodiments, describe in detail the specific embodiments, structures, features and their effects according to the present invention.

[0018] A fly ash-based composite water treatment agent for complex harmful components in sewage, the raw material composition of the composite water treatment agent includes: 30%-50% of fly ash, 20%-30% of modifier, 10%-20% of composite oxidant, 5%-15% of flocculant, 1%-5% of auxiliary agent; 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 to remove the impurities therein and activate its surface, improving its adsorption performance and reaction activity.

[0019] The component composition of the modifier includes: 30%-50% organic acids (citric acid, oxalic acid, malic acid), 30%-40% inorganic salts (ferrous sulfate, ferric chloride, calcium nitrate), and 10%-20% surfactants (sodium dodecylbenzenesulfonate, cetyltrimethylammonium bromide). This modifier can undergo chemical reactions and physical adsorption with the surface of fly ash to form a composite material with a rich pore structure and various active sites, enhancing its adsorption capacity for organic matter and heavy metal ions in sewage and its oxidation effect on ammonia nitrogen.

[0020] The component composition of the composite oxidant includes: 50%-70% persulfate, 20%-30% sulfite, and 5%-10% stabilizer (such as magnesium sulfate, zinc sulfate). This composite oxidant can generate strongly oxidizing free radicals during the water treatment process, undergo redox reactions with the organic matter in sewage, decompose it into harmless small-molecule substances, and at the same time can also oxidize some heavy metal ions in sewage, making them more easily adsorbed and removed by fly ash-based materials.

[0021] The flocculant is polyaluminum ferric chloride, polyacrylamide, or a mixture of both, and can aggregate the tiny particles and harmful substances that have been adsorbed and oxidized in sewage through electrostatic action and bridging action to form larger flocs, facilitating subsequent sedimentation and separation.

[0022] The auxiliary agent is a composite of a dispersant, a preservative, and a pH regulator, which can improve the stability and service life of the water treatment agent, and at the same time adjust the pH value of the sewage to a range conducive to the removal of harmful components.

[0023] As Figure 1 shown, the composite water treatment agent is prepared, and its preparation steps are as follows: S100. After grinding and screening fly ash, it is subjected to acid leaching treatment. The acid leaching solution is hydrochloric acid with a mass fraction of 10%-20%, the acid leaching temperature is 70°C - 90°C, and the acid leaching time is 1 - 3 hours. After the acid leaching is completed, filtration, washing, and drying are carried out; S200. The acid-leached fly ash is subjected to alkali washing treatment. The alkali washing solution 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, filtration, washing, and drying are carried out again to obtain pretreated fly ash; S300. The pretreated fly ash and the modifier are mixed in proportion, heated to 80°C - 120°C under stirring, and reacted for 2 - 4 hours to enable the modifier to fully contact the surface of the fly ash and undergo chemical reactions and physical adsorption to form modified fly ash; S400. Dissolve the composite oxidant, flocculant, and auxiliary agent separately in an appropriate amount of deionized water to prepare solutions of a certain concentration. Then disperse the modified fly ash in these solutions and mechanically stir and mix them to make each component evenly disperse on the surface and in the pores of the modified fly ash. S500. Dry the mixed slurry at a drying temperature of 40°C - 60°C until the moisture content is lower than 10%. Then perform crushing and screening to obtain fly ash-based composite water treatment agent particles with a particle size less than 150 μm.

[0024] Example 1

[0025] Raw material preparation Fly ash: Take 40%. Select fly ash from a coal power plant. First, grind it, then calcine it at 700°C for 3 hours, and then soak it in an 8% hydrochloric acid solution by mass for 2 hours. After filtration, wash it until neutral and dry for later use.

[0026] Modifier: Take 25%. Among them, organic acid (citric acid) accounts for 40%, inorganic salt (ferrous sulfate) accounts for 35%, and surfactant (sodium dodecylbenzenesulfonate) accounts for 25%.

[0027] Composite oxidant: Take 15%. Persulfate (potassium persulfate) accounts for 60%, sulfite (sodium sulfite) accounts for 25%, and stabilizer (magnesium sulfate) accounts for 15%.

[0028] Flocculant: Take 10%. Poly aluminum ferric chloride accounts for 70%, and polyacrylamide accounts for 30%.

[0029] Auxiliary agent: Take 5%. Dispersant (sodium polyacrylate) accounts for 40%, preservative (sodium benzoate) accounts for 25%, and pH regulator (sodium hydroxide) accounts for 35%.

[0030] Preparation process Leach the fly ash with a 15% hydrochloric acid solution by mass at 80°C for 2 hours, filter, wash, and dry.

[0031] Alkaline wash the acid-leached fly ash with a 10% sodium hydroxide solution by mass at 70°C for 1 hour, filter and wash again, and dry to obtain pretreated fly ash.

[0032] Mix the pretreated fly ash with the modifier, heat it to 100°C with stirring, and react for 3 hours to form modified fly ash.

[0033] Dissolve the composite oxidant, flocculant, and auxiliary agent separately in deionized water to prepare solutions, disperse the modified fly ash in the solutions, and mechanically stir and mix.

[0034] Dry the mixed slurry at 50°C until the moisture content is lower than 10%, crush and screen to obtain fly ash-based composite water treatment agent particles.

[0035] Usage method: 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 stand and settle for 45 minutes, and then filter and centrifuge to remove the suspended matter and harmful components in the supernatant.

[0036] Implementation effect: After testing, after treating the simulated sewage with the water treatment agent of this example, the removal rate of lead ions reached 95%, and the concentration of lead ions after treatment decreased from 50 mg / L to 2.5 mg / L; the removal rate of phenolic compounds was 90%, and the concentration decreased from 80 mg / L to 8 mg / L; the removal rate of ammonia nitrogen was 88%, and the concentration decreased 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 advanced treatment for reuse, indicating that the water treatment agent had significant effects in removing lead ions, phenolic compounds, and ammonia nitrogen, and could effectively purify the sewage.

[0037] Example Two

[0038] Raw material preparation Fly ash: Take 30%, grind it and calcine it at 600 °C for 2 hours, soak it in a hydrochloric acid solution with a mass fraction of 5% for 1 hour, and then filter, wash, and dry.

[0039] Modifier: Take 30%, organic acid (oxalic acid) accounts for 30%, inorganic salt (ferric chloride) accounts for 40%, and surfactant (cetyltrimethylammonium bromide) accounts for 30%.

[0040] Composite oxidant: Take 20%, persulfate (sodium persulfate) accounts for 70%, sulfite (potassium sulfite) accounts for 20%, and stabilizer (zinc sulfate) accounts for 10%.

[0041] Flocculant: Take 15%, polyaluminum ferric chloride accounts for 80%, and polyacrylamide accounts for 20%.

[0042] Auxiliary agent: Take 5%, dispersant (sodium polyacrylate) accounts for 50%, preservative (sodium benzoate) accounts for 20%, and pH regulator (sodium carbonate) accounts for 30%.

[0043] Preparation process Acid leaching: Acid leach with a hydrochloric acid solution with a mass fraction of 10% at 70 °C for 1 hour, and the subsequent treatment is the same as that in Example One.

[0044] Alkali washing: Alkali wash with a sodium hydroxide solution with a mass fraction of 5% at 60 °C for 0.5 hour, and the subsequent treatment is the same as that in Example One.

[0045] Modification: Heat it to 80 °C with the modifier under stirring and react for 4 hours.

[0046] Mixing and Drying: The same as Example 1.

[0047] 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. Stir for 15 minutes, settle for 50 minutes, and the subsequent treatment is the same as in Example 1.

[0048] Implementation Effect: The water treatment agent in Example 2 has remarkable treatment effects on simulated sewage. The removal rate of mercury ions is as high as 88%, and its concentration drops from 20 mg / L to 2.4 mg / L after treatment; the removal rate of polycyclic aromatic hydrocarbons is 85%, and the concentration drops from 60 mg / L to 9 mg / L; the removal rate of total phosphorus is 82%, and the concentration drops from 30 mg / L to 5.4 mg / L. The water quality of the treated sewage is significantly improved, the water transparency is greatly enhanced, and there are no visible impurities, proving that the water treatment agent has outstanding removal capabilities for mercury ions, polycyclic aromatic hydrocarbons, and total phosphorus, and can efficiently treat sewage containing such complex and harmful components.

[0049] Example 3 Raw Material Preparation Fly Ash: Take 50%. Use fly ash from a local power plant, grind it, calcine it at 800 °C for 4 hours, soak it in a 10% hydrochloric acid solution by mass for 3 hours, and then filter, wash, and dry it.

[0050] Modifier: Take 20%. Organic acid (malic acid) accounts for 50%, inorganic salt (calcium nitrate) accounts for 30%, and surfactant (sodium dodecylbenzenesulfonate) accounts for 20%.

[0051] Composite Oxidant: Take 10%. Persulfate (ammonium persulfate) accounts for 50%, sulfite (sodium sulfite) accounts for 30%, and stabilizer (magnesium sulfate) accounts for 20%.

[0052] Flocculant: Take 15%. Polyaluminum ferric chloride accounts for 60%, and polyacrylamide accounts for 40%.

[0053] Auxiliary Agent: Take 5%. Dispersant (sodium polyacrylate) accounts for 30%, preservative (sodium benzoate) accounts for 30%, and pH regulator (hydrochloric acid) accounts for 40%.

[0054] Preparation Process Acid Leaching: Acid leach with a 20% hydrochloric acid solution by mass at 90 °C for 3 hours.

[0055] Alkali Washing: Alkali wash with a 15% sodium hydroxide solution by mass at 80 °C for 2 hours.

[0056] Modification: Heat to 120 °C with stirring and react for 2 hours.

[0057] Mixing and Drying: The same as Example 1.

[0058] Usage method: Treat simulated sewage containing cadmium ions (30 mg / L), phenolic compounds (100 mg / L), and ammonia nitrogen (50 mg / L). The dosage is 1 g / L. Stir for 30 minutes and settle for 60 minutes. The subsequent treatment is the same as that in Example 1.

[0059] Implementation effect: When treating simulated sewage containing cadmium ions, phenolic compounds, and ammonia nitrogen, the water treatment agent in Example 3 showed excellent performance. The removal rate of cadmium ions reached 98%, and the concentration decreased from 30 mg / L to 0.6 mg / L after treatment; the removal rate of phenolic compounds was 92%, and the concentration decreased from 100 mg / L to 8 mg / L; the removal rate of ammonia nitrogen was 90%, and the concentration decreased from 50 mg / L to 5 mg / L. The treated sewage had excellent water quality and could meet the requirements of various water use scenarios, which fully demonstrated that the water treatment agent could accurately and efficiently remove complex harmful components in sewage.

[0060] Example 4 Raw material preparation Fly ash: Take 35%. The pretreatment is the same as that in Example 1, but the calcination temperature is 650 °C.

[0061] Modifier: Take 28%. Organic acid (citric acid) accounts for 45%, inorganic salt (ferrous sulfate) accounts for 32%, and surfactant (cetyltrimethylammonium bromide) accounts for 23%.

[0062] Composite oxidant: Take 16%. Persulfate (potassium persulfate) accounts for 65%, sulfite (potassium sulfite) accounts for 22%, and stabilizer (zinc sulfate) accounts for 13%.

[0063] Flocculant: Take 10%. Polyaluminum ferric chloride accounts for 75%, and polyacrylamide accounts for 25%.

[0064] Auxiliary agent: Take 1%. Dispersant (sodium polyacrylate) accounts for 45%, preservative (sodium benzoate) accounts for 25%, and pH regulator (sodium hydroxide) accounts for 30%.

[0065] Preparation process Acid leaching: Acid leach with a 12% hydrochloric acid solution at 75 °C for 1.5 hours.

[0066] Alkali washing: Alkali wash with an 8% sodium hydroxide solution at 65 °C for 1.2 hours.

[0067] Modification: Heat to 90 °C with stirring and react for 3.5 hours.

[0068] Mixing and drying: The same as in Example 1.

[0069] Usage method: For simulated sewage containing lead ions (40 mg / L), polycyclic aromatic hydrocarbons (70 mg / L), and total phosphorus (25 mg / L), the dosage is 0.6 g / L, stir for 25 minutes, sediment for 40 minutes, and the subsequent treatment is the same as in Example 1.

[0070] Implementation effect: The water treatment agent in Example 4 has good removal effects on lead ions, polycyclic aromatic hydrocarbons, and total phosphorus in the simulated sewage. The removal rate of lead ions is 96%, and the concentration after treatment drops from 40 mg / L to 1.6 mg / L; the removal rate of polycyclic aromatic hydrocarbons is 87%, and the concentration drops from 70 mg / L to 9.1 mg / L; the removal rate of total phosphorus is 81.25%, and the concentration drops from 25 mg / L to 4.75 mg / L, indicating that this water treatment agent has high reliability and stability in removing various complex harmful components.

[0071] Example 5 Raw material preparation Fly ash: Take 45%, and the pretreatment is the same as in Example 2, but the calcination time is 3.5 hours.

[0072] Modifier: Take 22%, organic acid (malic acid) accounts for 42%, inorganic salt (ferric chloride) accounts for 38%, and surfactant (sodium dodecylbenzenesulfonate) accounts for 20%.

[0073] Composite oxidant: Take 13%, persulfate (sodium persulfate) accounts for 55%, sulfite (sodium sulfite) accounts for 28%, and stabilizer (magnesium sulfate) accounts for 17%.

[0074] Flocculant: Take 15%, polyaluminum ferric chloride accounts for 72%, and polyacrylamide accounts for 28%.

[0075] Auxiliary agent: Take 5%, dispersant (sodium polyacrylate) accounts for 40%, preservative (sodium benzoate) accounts for 28%, and pH regulator (sodium carbonate) accounts for 32%.

[0076] Preparation process Acid leaching: Acid leach with a 18% hydrochloric acid solution at 85 °C for 2.5 hours.

[0077] Alkali washing: Alkali wash with a 12% sodium hydroxide solution at 75 °C for 1.5 hours.

[0078] Modification: Heat to 110 °C with stirring and react for 2.5 hours.

[0079] Mixing and drying: The same as in Example 1.

[0080] Usage method: Treat simulated sewage containing mercury ions (15 mg / L), phenolic compounds (90 mg / L), and ammonia nitrogen (45 mg / L), the dosage is 0.7 g / L, stir for 18 minutes, sediment for 55 minutes, and the subsequent treatment is the same as in Example 1.

[0081] Implementation effect: After treating the simulated sewage with the water treatment agent of Example 5, the removal rate of mercury ions is 90%, and the concentration drops from 15 mg / L to 1.5 mg / L; the removal rate of phenolic compounds is 90%, and the concentration drops from 90 mg / L to 9 mg / L; the removal rate of ammonia nitrogen is 89%, and the concentration drops from 45 mg / L to 4.95 mg / L. The quality of the treated sewage is stable, indicating that the water treatment agent in this example has an ideal removal effect on mercury ions, phenolic compounds and ammonia nitrogen in sewage and can effectively improve the quality of sewage.

[0082] Comparative Example 1 Raw material preparation: Fly ash: Take 50%, and the treatment method is the same as that in Example 3.

[0083] Composite oxidant: Take 20%, and the composition is the same as that in Example 3.

[0084] Flocculant: Take 20%, and the composition is the same as that in Example 3.

[0085] Auxiliary agent: Take 10%, and the composition is the same as that in Example 3.

[0086] Preparation process The pretreatment of fly ash is the same as that in Example 3.

[0087] Mix the pretreated fly ash directly with the solutions of the composite oxidant, flocculant and auxiliary agent, and stir mechanically without using a modifier.

[0088] The drying, crushing and screening are the same as those in Example 1.

[0089] Usage method: Treat the 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, and then filter and centrifuge.

[0090] Implementation effect: Due to the lack of a modifier, the effect of Comparative Example 1 in treating the simulated sewage is not good. The removal rate of lead ions is only 70%, and the concentration after treatment is 15 mg / L; the removal rate of phenolic compounds is 75%, and the concentration is 20 mg / L; the removal rate of ammonia nitrogen is 70%, and the concentration is 12 mg / L. The treated sewage still contains more harmful components and the water quality is turbid, indicating that the modifier plays a key role in enhancing the removal ability of the water treatment agent for complex harmful components, and the lack of a modifier will seriously affect the treatment effect.

[0091] Comparative Example 2 Raw material preparation Fly ash: Take 40%, and the treatment method is the same as that in Example 1.

[0092] Modifier: Take 30%, and the composition is the same as that in Example 1.

[0093] Flocculant: Take 20%, with the same composition as in Example 1.

[0094] Auxiliary agent: Take 10%, with the same composition as in Example 1.

[0095] Preparation process The pretreatment and modification of fly ash are the same as in Example 1.

[0096] Mix the modified fly ash with the solutions of the flocculant and the auxiliary agent, and stir mechanically without using a composite oxidant.

[0097] Drying, pulverizing, and screening are the same as in Example 1.

[0098] Usage method: Treat 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. Stir for 15 minutes, settle for 50 minutes, and then filter and centrifuge.

[0099] Implementation effect: In Comparative Example 2, the composite oxidant was not used. After treating the simulated sewage, the removal rate of mercury ions was 75%, and the concentration after treatment was 5 mg / L; the removal rate of polycyclic aromatic hydrocarbons was 70%, and the concentration was 18 mg / L; the removal rate of total phosphorus 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 relatively high, and the water quality was not effectively purified. This shows that the composite oxidant is crucial for the efficient removal of organic pollutants and some heavy metal ions in sewage. The lack of the composite oxidant will significantly reduce the treatment effect of the water treatment agent.

[0100] There are different differences in the effects of the above-mentioned examples and comparative examples on the simulated sewage. Different component compositions have different effects on the performance of the water treatment agent. Further, the raw material ratios of the examples and comparative examples are shown in Table 1 below: Table 1 Raw material ratio table of each example and comparative example of fly ash-based composite water treatment agent 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. Embodiments 1 to 5 showed excellent treatment capabilities, and the removal rates of heavy metal ions such as lead, mercury, cadmium, polycyclic aromatic hydrocarbons, phenolic compounds and other organic pollutants, and nutrients such as ammonia nitrogen and total phosphorus in different simulated sewage were relatively high, indicating 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 modifiers, and the removal rates of lead ions, phenolic compounds and ammonia nitrogen are significantly lower than those of the embodiments; comparative example 2 does not use a composite oxidant, and the removal effects of mercury ions, polycyclic aromatic hydrocarbons and total phosphorus are greatly reduced. The treated sewage still contains more harmful components, which fully illustrates the key role of modifiers and composite oxidants in enhancing the ability of water treatment agents to remove complex harmful components.

[0101] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. 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, This composite water treatment agent is composed of raw materials with the following mass percentages as follows: Fly ash: 30% - 50%; Modifier: 20% - 30%; Composite oxidant: 10% - 20%; Flocculant: 5% - 15%; Auxiliary agent: 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 composite of organic acid, inorganic salt and surfactant, adsorbs organic matters and heavy metal ions in the sewage, and oxidizes ammonia nitrogen; The composite oxidant undergoes an oxidation-reduction reaction with the organic matters in the sewage, decomposes them into harmless small molecule substances, and simultaneously oxidizes heavy metal ions in the sewage; The flocculant is a mixture of polyaluminum ferric chloride and polyacrylamide, and is used to aggregate the tiny particles and harmful substances that have been adsorbed and oxidized in the sewage for sedimentation and separation; The auxiliary agent is a composite of dispersant, preservative and pH regulator, and is used to adjust the pH value of the sewage.

2. The fly ash-based composite water treatment agent for complex harmful components in sewage according to claim 1, wherein The pretreatment process of the fly ash is as follows: 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.

3. The fly ash-based composite water treatment agent for complex harmful components in sewage according to claim 1, wherein The modifier is composed of components with the following mass percentages as follows: 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 cetyltrimethylammonium bromide.

4. A 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 components with the following mass percentages: Persulfate: 50% - 70%; Sulfite: 20% - 30%; Stabilizer: 5% - 10%; The stabilizer is one of magnesium sulfate and zinc sulfate.

5. 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 components with the following mass percentages: Polyaluminum ferric chloride: 60% - 80%; Polacrylamide: 20% - 40%.

6. The fly ash-based composite water treatment agent for complex harmful components in sewage according to claim 1, wherein, The auxiliary agent is composed of components with the following mass percentages as follows: Dispersant: 30% - 50%; Preservative: 20% - 30%; pH regulator: 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.

7. A fly ash-based composite water treatment agent for complex harmful components in sewage according to any one of claims 1-6, characterized in that, The preparation steps of the composite water treatment agent are as follows: The fly ash is ground and screened, and then undergoes acid leaching treatment. The acid leaching solution is a hydrochloric acid solution with a mass fraction of 10% - 20%, the acid leaching temperature is 70 °C - 90 °C, the acid leaching time is 1 - 3 hours. After acid leaching, filtration, washing and drying are carried out; The acid-leached fly ash is subjected to alkali washing treatment. The alkali washing solution is sodium hydroxide with a mass fraction of 5% - 15%, the alkali washing temperature is 60 °C - 80 °C, the alkali washing time is 0.5 - 2 hours. After alkali washing, filtration, washing and drying are carried out again to obtain the pretreated fly ash; Mix the pretreated fly ash with a modifier, heat it to 80°C - 120°C under stirring, and react for 2 - 4 hours to enable the modifier to fully contact the surface of the fly ash and undergo chemical reactions and physical adsorption, forming modified fly ash; Dissolve the composite oxidant, flocculant, and auxiliary agent separately in deionized water to prepare solutions, disperse the modified fly ash in the solutions, and conduct mechanical stirring and mixing to uniformly disperse each component on the surface and in the pores of the modified fly ash; Conduct a drying treatment on the mixed slurry at a drying temperature of 40°C - 60°C until the moisture content is lower than 10%, and then conduct crushing and screening to obtain fly ash-based composite water treatment agent particles.

8. The fly ash-based composite water treatment agent for complex harmful components in sewage according to claim 7, characterized in that, When using this water treatment agent, according to the types and concentrations of complex harmful components in the sewage, add the fly ash-based composite water treatment agent to the sewage at a dosage of 0.1 g / L - 1 g / L, conduct mechanical stirring to fully mix and contact the water treatment agent with the sewage, with a stirring time of 10 - 30 minutes, then conduct static sedimentation for 30 - 60 minutes, and remove the suspended solids and harmful components in the supernatant through filtration and centrifugal separation to achieve the purpose of purifying the sewage.

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