Composite sewage treatment agent, sewage treatment method and application

Abstract

The invention provides a composite sewage treatment agent, a sewage treatment method and application, and belongs to the technical field of water treatment agents. The composite sewage treatment agent is prepared from an agent A, an agent B and an agent C. The agent A is prepared from, by mass, 40-60 parts of modified silicon-calcium-based mineral materials, 10-20 parts of organic flocculants, 5-10 parts of structure conditioning agents, 5-10 parts of inorganic flocculants and 20-30 parts of filler. The agent B is prepared from the following raw materials in parts by mass: 30 to 50 parts of tea seed meal extract microcapsules, 20 to 40 parts of a carbon source, 10 to 20 parts of a trace element mixture, 5 to 15 parts of a nitrification accelerant and 3 to 8 parts of a binder; the agent C is prepared from the following raw materials in parts by mass: 70 to 80 parts of coated sodium bicarbonate and 20 to 30 parts of nanoscale seed crystal. Under the combined action of the agent A, the agent B and the agent C, the sewage treatment effect is improved, and up-to-standard discharge of effluent is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of water treatment agents, and in particular to a composite sewage treatment agent and a sewage treatment method and application. Background Art

[0002] Industrial wastewater mainly refers to intermediate products, by-products, cleaning fluids and extraction solvents generated in the industrial production process. The vast majority of discharged industrial wastewater is organic chemical raw materials or intermediates in various forms. Typical industries such as electronics, coking, steel, printing and dyeing have always been major emitters of organic pollutants. In addition, there are chemicals such as pesticides, fertilizers and herbicides and related additives, as well as heavy metal pollutants. These substances enter the environment through various channels and are eventually discharged into rivers and lakes in the form of wastewater. On the one hand, due to the limited self-purification capacity of natural water bodies, if the pollutants discharged into the water body exceed the ecological carrying capacity of the natural water body or cause irreversible pollution to it, on the other hand, these pollutants discharged into the environment have certain biological activity, which will cause toxic reactions or carcinogenic effects in aquatic plants and animals, and may even directly cause harm to human health.

[0003] Patent application CN202311647122.5 discloses a sewage treatment agent, which uses an oxidant, a non-oxidant and a flocculant as raw materials. The iron-based substances in the non-oxidant can catalyze the oxidation of percarbonate to generate hydroxyl radicals, greatly improving the oxidizability and oxidation rate of percarbonate; aminosulfonic acid, as a preservative and stabilizer, can further enhance the effect of the sewage treatment agent in treating black and odorous water bodies, and extend the treatment time, but the above-mentioned existing technology is not efficient in removing organic pollutants in sewage. Patent application CN201911307611.X discloses a papermaking wastewater treatment agent, including a flocculant composed, by weight, of 5-10 parts polyferric sulfate, 10-15 parts polyferric silicate, 10-15 parts chitosan, 20-30 parts sodium alginate, 5-10 parts slaked lime, 5-10 parts polyacrylamide, and 1-2 parts acetic acid. It also includes 5-10 parts of a coagulant aid, which includes one or more of activated silicic acid, activated water glass, and sodium silicate. However, the acrylamide prepared in the above patent has a low molecular weight and poor flocculation effect.

[0004] Existing sewage treatment agents have a single treatment effect and are unable to cope with complex water quality: traditional flocculants (such as PAC and PAM) mainly target suspended matter and colloids, and have limited removal effects on pollutants such as soluble, difficult-to-degrade organic matter, heavy metal ions, and high ammonia nitrogen. They often require multiple processes to be connected in series, resulting in lengthy processes and high costs. Summary of the Invention

[0005] The present application is made in view of the above problems, and its purpose is to provide a composite sewage treatment agent and sewage treatment method and application, which can comprehensively treat sewage with good treatment effect.

[0006] Specifically, the first aspect of the present application provides a composite sewage treatment agent, including agent A, agent B and agent C. The agent A comprises the following raw materials in mass fraction: 40-60 parts of modified calcium-silicon-based mineral material, 10-20 parts of organic flocculant, 5-10 parts of structure regulator, 5-10 parts of inorganic flocculant, and 20-30 parts of filler; The agent B comprises the following raw materials in mass fraction: 30-50 parts of tea seed meal extract microcapsules, 20-40 parts of carbon source, 10-20 parts of trace element mixture, 5-15 parts of nitration promoter, and 3-8 parts of binder; The agent C comprises the following raw materials in mass fraction: 70-80 parts of coated sodium bicarbonate and 20-30 parts of nano-sized seed crystals.

[0007] Furthermore, the modified silicon-calcium-based mineral material in the agent A is sepiolite or diatomaceous earth loaded with nano-calcium oxide and iron salt; and / or The structure regulator is disodium hydrogen phosphate or sodium dihydrogen phosphate; and / or The organic flocculant is a zwitterionic polyacrylamide; and / or The inorganic flocculant is polysilicate ferric sulfate.

[0008] Furthermore, the preparation method of the tea seed meal extract microcapsules in the agent B is: using the sharp hole-coagulation bath method, dripping the core material solution containing sodium alginate and tea seed meal extract into a coagulation bath containing calcium ions and chitosan to form gel microcapsules.

[0009] Furthermore, the trace element mixture in the agent B includes CuSO4·5H2O 1-3%, ZnSO4·7H2O 2-4%, Na2MoO4·2H2O 1-2%, CoCl2·6H2O 0.3-0.8%, and zeolite powder carrier 90-95%; and / or The nitration accelerator is a mixture of ammonium chloride and urea in a mass ratio of 1:0.8-1.2; and / or The binder is sodium carboxymethyl cellulose.

[0010] Furthermore, the preparation method of the coated sodium bicarbonate in the agent C is: using a solution of a biodegradable polymer material as a coating liquid, coating the sodium bicarbonate particles, and controlling the coating weight gain to be 10%-20%.

[0011] A second aspect of the present invention provides a sewage treatment method using the composite sewage treatment agent, comprising the following steps: (1) Add agent A to the industrial wastewater to be treated to carry out coagulation and sedimentation reaction to complete the primary treatment; (2) introducing the effluent from step (1) into a biochemical treatment unit and adding agent B thereto for bioaugmentation treatment; (3) Add Agent C to the effluent of step (2), stir and react, and precipitate to complete the deep treatment.

[0012] Furthermore, in step (1), after adding agent A, the mixture was stirred for 250-350 seconds. -1 , 70-90s -1 and 20-40 s -1 The three-stage reaction is carried out by stirring with a stirring intensity G value of .

[0013] Furthermore, the agent B is added to the anoxic zone or water inlet of the biochemical treatment unit at a mass ratio of agent B to influent COD of 1:50-200.

[0014] Furthermore, the dosage of the agent C is controlled according to the molar ratio of bicarbonate to residual calcium ions and heavy metal ions in the wastewater (1.0-1.5):1, and the reaction stirring intensity G value is 15-25 s -1 .

[0015] The third aspect of the present application provides an application of the composite sewage treatment agent in sewage treatment.

[0016] The present invention has the following beneficial effects: The present invention not only achieves efficient removal of multiple pollutants through the rational combination and synergistic effect of Agent A, Agent B, and Agent C, but also demonstrates unique advantages in sludge treatment and cost control. Agent A mainly plays the role of flocculation and mineralization. The modified calcium-silicon-based mineral material has a large specific surface area and a rich pore structure, which can adsorb suspended matter, colloids and some organic matter in sewage. The synergistic effect of organic flocculants and inorganic flocculants can cause the fine particles in the sewage to condense into larger flocs, which is convenient for subsequent precipitation and separation. The structure regulator helps to adjust the structure of the flocs, making them more compact and improving the precipitation effect. The filler can increase the weight of the flocs and accelerate the precipitation rate. In the primary treatment, the addition of Agent A can effectively remove most of the suspended matter and some organic matter in the sewage, and reduce the turbidity and COD of the sewage. By accurately controlling the dosage and stirring intensity of Agent A, the coagulation and sedimentation reaction can achieve the best effect. The water quality of the sewage treated with Agent A has been preliminarily improved, laying a good foundation for subsequent biochemical treatment and deep treatment. Agent B primarily functions as a bioactivator. The tea seed meal extract microcapsules provide a suitable growth environment and nutrients for microorganisms, optimizing their flora structure and enhancing their activity and metabolic capacity. The trace element mixture provides essential trace elements for microbial growth and metabolism, helping to maintain normal microbial physiological functions. The nitrification accelerator promotes nitrification and improves the removal efficiency of ammonia nitrogen from wastewater. During the bioaugmentation treatment phase, Agent B is added to the anoxic zone or inlet of the biochemical treatment unit to rapidly activate microbial activity and enhance the biochemical system's ability to remove organic matter and ammonia nitrogen. Microencapsulated tea seed meal extract specifically inhibits filamentous bacterial bulking, preventing sludge bulking and ensuring stable operation of the biochemical system. Furthermore, the microbial flora in Agent B can adapt to fluctuations in toxic substances and loads in the wastewater, enhancing the biochemical system's resilience to shocks. After treatment with Agent B, the organic matter and ammonia nitrogen content in wastewater is further reduced, significantly improving water quality. Furthermore, the use of Agent B helps improve the treatment efficiency of the biochemical system, reducing the residence time in the biochemical treatment unit and lowering treatment costs. In addition, the microbial flora in agent B can convert some organic matter into carbon dioxide and water, achieving harmless treatment of organic matter. Agent C is responsible for deep mineralization. The coated sodium bicarbonate slowly releases bicarbonate ions in water, reacting with the residual calcium ions and heavy metal ions in the wastewater to form insoluble carbonate precipitates, thereby achieving deep removal of heavy metal ions. Nano-scale crystal seeds provide a crystallization core for the precipitation reaction, promote the formation and growth of the precipitate, and improve the precipitation efficiency. In the deep treatment stage, the dosage of Agent C is controlled according to the molar ratio of bicarbonate to residual calcium ions and heavy metal ions in the wastewater (1.0-1.5):1, and the reaction stirring intensity G value is 15-25 s -1 , which can ensure that the precipitation reaction proceeds fully. Agent C further converts the remaining pollutants into stable solids, so that heavy metal ions and other pollutants in the sewage are deeply removed. After the sewage is treated with Agent C, the content of pollutants such as heavy metal ions and color is greatly reduced, and the effluent water quality is better than the Class A standard in all aspects. At the same time, the use of Agent C further reduces the volume of sludge, reduces the leaching toxicity of sludge, and makes the sludge easier to handle and utilize as a resource. The entire composite sewage treatment agent realizes all-round and in-depth treatment of sewage through the synergistic effect of Agent A, Agent B, and Agent C, and has broad application prospects in the field of sewage treatment. DETAILED DESCRIPTION In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is described and illustrated below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are merely used to explain this application and are not intended to limit this application. Based on the embodiments provided in this application, all other embodiments obtained by those of ordinary skill in the art without making any creative work are within the scope of protection of this application.

[0017] Obviously, the following descriptions are merely some examples or embodiments of the present application. Those skilled in the art can apply the present application to other similar scenarios without inventive effort. Furthermore, it is also understood that, although the effort involved in such a development process may be complex and lengthy, for those skilled in the art related to the content disclosed in the present application, changes in design, manufacturing, or production based on the technical content disclosed in the present application are merely conventional technical means and should not be construed as an insufficiency of the content disclosed in the present application.

[0018] The first aspect of the present application provides a composite sewage treatment agent, comprising agent A, agent B and agent C. The agent A comprises the following raw materials in mass fraction: 40-60 parts of modified calcium-silicon-based mineral material, 10-20 parts of organic flocculant, 5-10 parts of structure regulator, 5-10 parts of inorganic flocculant, and 20-30 parts of filler; The agent B comprises the following raw materials in mass fraction: 30-50 parts of tea seed meal extract microcapsules, 20-40 parts of carbon source, 10-20 parts of trace element mixture, 5-15 parts of nitration promoter, and 3-8 parts of binder; The agent C comprises the following raw materials in mass fraction: 70-80 parts of coated sodium bicarbonate and 20-30 parts of nano-sized seed crystals.

[0019] The present invention not only achieves efficient removal of multiple pollutants through the rational combination and synergistic effect of Agent A, Agent B, and Agent C, but also demonstrates unique advantages in sludge treatment and cost control. Agent A mainly plays the role of flocculation and mineralization. The modified calcium-silicon-based mineral material has a large specific surface area and a rich pore structure, which can adsorb suspended matter, colloids and some organic matter in sewage. The synergistic effect of organic flocculants and inorganic flocculants can cause the fine particles in the sewage to condense into larger flocs, which is convenient for subsequent precipitation and separation. The structure regulator helps to adjust the structure of the flocs, making them more compact and improving the precipitation effect. The filler can increase the weight of the flocs and accelerate the precipitation rate. In the primary treatment, the addition of Agent A can effectively remove most of the suspended matter and some organic matter in the sewage, and reduce the turbidity and COD of the sewage. By accurately controlling the dosage and stirring intensity of Agent A, the coagulation and sedimentation reaction can achieve the best effect. The water quality of the sewage treated with Agent A has been preliminarily improved, laying a good foundation for subsequent biochemical treatment and deep treatment. Agent B primarily functions as a bioactivator. The tea seed meal extract microcapsules provide a suitable growth environment and nutrients for microorganisms, optimizing their flora structure and enhancing their activity and metabolic capacity. The trace element mixture provides essential trace elements for microbial growth and metabolism, helping to maintain normal microbial physiological functions. The nitrification accelerator promotes nitrification and improves the removal efficiency of ammonia nitrogen from wastewater. During the bioaugmentation treatment phase, Agent B is added to the anoxic zone or inlet of the biochemical treatment unit to rapidly activate microbial activity and enhance the biochemical system's ability to remove organic matter and ammonia nitrogen. Microencapsulated tea seed meal extract specifically inhibits filamentous bacterial bulking, preventing sludge bulking and ensuring stable operation of the biochemical system. Furthermore, the microbial flora in Agent B can adapt to fluctuations in toxic substances and loads in the wastewater, enhancing the biochemical system's resilience to shocks. After treatment with Agent B, the organic matter and ammonia nitrogen content in wastewater is further reduced, significantly improving water quality. Furthermore, the use of Agent B helps improve the treatment efficiency of the biochemical system, reducing the residence time in the biochemical treatment unit and lowering treatment costs. In addition, the microbial flora in agent B can convert some organic matter into carbon dioxide and water, achieving harmless treatment of organic matter. Agent C is responsible for deep mineralization. The coated sodium bicarbonate slowly releases bicarbonate ions in water, reacting with the residual calcium ions and heavy metal ions in the wastewater to form insoluble carbonate precipitates, thereby achieving deep removal of heavy metal ions. Nano-scale crystal seeds provide a crystallization core for the precipitation reaction, promote the formation and growth of the precipitate, and improve the precipitation efficiency. In the deep treatment stage, the dosage of Agent C is controlled according to the molar ratio of bicarbonate to residual calcium ions and heavy metal ions in the wastewater (1.0-1.5):1, and the reaction stirring intensity G value is 15-25 s -1, which can ensure that the precipitation reaction proceeds fully. Agent C further converts the remaining pollutants into stable solids, so that heavy metal ions and other pollutants in the sewage are deeply removed. After the sewage is treated with Agent C, the content of pollutants such as heavy metal ions and color is greatly reduced, and the effluent water quality is better than the Class A standard in all aspects. At the same time, the use of Agent C further reduces the volume of sludge, reduces the leaching toxicity of sludge, and makes the sludge easier to handle and utilize as a resource. The entire composite sewage treatment agent realizes all-round and in-depth treatment of sewage through the synergistic effect of Agent A, Agent B, and Agent C, and has broad application prospects in the field of sewage treatment.

[0020] In this embodiment, the mass fraction of the modified silicon-calcium-based mineral material in the agent A is any value or any combination of values ​​selected from 40 parts, 45 parts, 50 parts, 55 parts, and 60 parts. When the mass fraction of the modified silicon-calcium-based mineral material is less than 40 parts, its adsorption capacity is insufficient, and it is difficult to effectively remove suspended matter, colloids and some organic matter in the sewage, resulting in the turbidity and COD reduction effect of the sewage after primary treatment is not obvious, and it is impossible to lay a good foundation for subsequent treatment; when the mass fraction is higher than 60 parts, the cost of the agent A will increase, and it may cause waste of materials. At the same time, too much material may affect the formation of flocs and the precipitation effect.

[0021] The modified calcium-silicon-based mineral material comprises 70% of 100-mesh sepiolite powder, 20% of nano calcium oxide (CaO), and 10% of ferric chloride hexahydrate (FeCl 3 ·6H 2 O).

[0022] The weight percentage of the organic flocculant can be any number or combination of 10, 12, 15, 18, or 20 parts. If the weight percentage of the organic flocculant is less than 10 parts, it will be difficult to fully agglomerate fine particles in the sewage into larger flocs when acting synergistically with the inorganic flocculant, which is not conducive to sedimentation and separation. If the weight percentage is greater than 20 parts, the flocs may be too loose and difficult to settle, which will also increase treatment costs. The organic flocculant is a zwitterionic polyacrylamide with a molecular weight of 8-10 million and an ionicity of 20%.

[0023] The structure regulator is disodium hydrogen phosphate, and its mass fraction is any value or any combination of 5 parts, 6 parts, 8 parts, 9 parts, and 10 parts. When the mass fraction is less than 5 parts, the regulating effect on the floc structure is not significant, the flocs are not dense enough, and the sedimentation effect is poor; when it is higher than 10 parts, it may change the properties of the flocs and affect the sedimentation process.

[0024] The inorganic flocculant is polyferric silicate sulfate, and its mass fraction is any value or any combination of 5 parts, 6 parts, 8 parts, 9 parts, and 10 parts. When it is less than 5 parts, the coagulation effect of the synergistic organic flocculant is poor and the particles in the sewage cannot be effectively removed; when it is more than 10 parts, it may cause the ion concentration in the sewage to be too high, affecting subsequent treatment.

[0025] The filler is anhydrous sodium sulfate, and its mass fraction is any value or any combination of 20 parts, 22 parts, 25 parts, 28 parts, and 30 parts. When it is less than 20 parts, the weight of the flocs does not increase significantly and the sedimentation rate is slow; when it is more than 30 parts, the volume and cost of Agent A will be increased, and the effects of other ingredients may be affected.

[0026] The preparation method of the agent A is as follows: Place 100-mesh sepiolite powder in a high-efficiency mixer, heat to 80-90°C, slowly add measured ferric chloride hexahydrate (dissolved in a small amount of deionized water), stir and react for 40 minutes, then add nano-CaO powder and continue stirring for 60 minutes to ensure sufficient loading and mixing. After taking out, dry at 105°C to constant weight and set aside.

[0027] The prepared modified sepiolite, zwitterionic polyacrylamide, disodium hydrogen phosphate, polysilicate ferric sulfate, and anhydrous sodium sulfate were added into a three-dimensional motion mixer in proportion. The mixer was operated at a speed of 15-20 rpm for 45-60 minutes to ensure that the components were evenly distributed. The material was discharged and sealed in a moisture-proof packaging bag for storage to obtain Agent A.

[0028] The mass fraction of the tea seed meal extract microcapsules in Agent B is any value selected from 30, 35, 40, 45, and 50 parts, or any combination of these values. When the mass fraction is less than 30 parts, the growth environment and nutrients provided to the microorganisms are insufficient, making it difficult to effectively optimize the microbial flora structure and enhance microbial activity. When the mass fraction is greater than 50 parts, the microorganisms may grow too vigorously, consuming excessive carbon sources and other substances, thereby affecting the treatment effect. The core material of the tea seed meal extract microcapsules is tea saponin extract, and the wall material is sodium alginate-chitosan.

[0029] The mass fraction of the carbon source can be any number or combination of 20, 25, 30, 35, or 40 parts. When the mass fraction is less than 20 parts, the microorganisms lack sufficient energy, their metabolic capacity is limited, and the removal of organic matter and ammonia nitrogen is affected. When the mass fraction is greater than 40 parts, the carbon source may be wasted and may cause excessive microbial growth, leading to other problems. The carbon source comprises 60% soluble starch and 40% glucose.

[0030] The mass fraction of the trace element mixture is any value or any combination of 10 parts, 12 parts, 15 parts, 18 parts, and 20 parts. When it is less than 10 parts, it cannot provide sufficient trace elements for the microorganisms, affecting the normal physiological functions of the microorganisms; when it is more than 20 parts, it may cause an imbalance of trace elements in the microorganisms, affecting their growth and metabolism.

[0031] The mass fraction of the nitrification promoter is any value or combination of 5, 8, 10, 12, or 15 parts. When the mass fraction is less than 5 parts, the promoting effect on the nitrification reaction is not significant, and the ammonia nitrogen removal efficiency is low. When the mass fraction is greater than 15 parts, the environment of the biochemical system may be changed, affecting the growth of microorganisms. The ammonium chloride and urea in the nitrification promoter are mixed in a mass ratio of 1:1.

[0032] The binder is sodium carboxymethyl cellulose, and its mass fraction is any value or any combination of 3 parts, 4 parts, 5 parts, 6 parts, and 8 parts. When it is less than 3 parts, it cannot effectively bind other ingredients, affecting the molding and use effect of Agent B; when it is more than 8 parts, it may affect the release and effect of other ingredients in Agent B.

[0033] Agent B is used to precisely regulate the colony structure of the biochemical system, inhibit filamentous bacteria, provide a slow-release carbon source and trace elements, and enhance system stability. The preparation method of Agent B is as follows: Tea seed meal powder was mixed with 60% ethanol solution at a solid-liquid ratio of 1:10, and refluxed at 60°C for 2 hours. The mixture was filtered and concentrated to obtain a crude tea saponin extract. A 2% sodium alginate solution and tea saponin extract were mixed at a volume ratio of 4:1 using a sharp hole-coagulation bath method to form a core material. The core material was slowly dripped into a coagulation bath containing 1.5% calcium chloride and 0.5% chitosan (dissolved in 1% acetic acid solution) using a peristaltic pump. The water droplets instantly formed gel beads (microcapsules) in the coagulation bath. After curing and crosslinking for 30 minutes, the gel beads were removed, washed with deionized water, and vacuum-dried at 40°C to obtain tea saponin microcapsules. Add the aforementioned microcapsules, composite carbon source, trace element mixture, nitration accelerator, and sodium carboxymethyl cellulose to a trough mixer. Spray with a small amount of deionized water to moderate the moisture content. Use an oscillating granulator to granulate through a 20-mesh screen. Dry the wet granules in a fluidized bed at 50°C until the moisture content is <5% to obtain Agent B.

[0034] Agent B microencapsulates tea saponin for microbial flora regulation, achieving sustained release and targeted effects, and avoiding the impact of instantaneous high concentrations on the microbial flora.

[0035] The weight percentage of the coated sodium bicarbonate in Agent C is any value selected from 70, 72, 75, 78, and 80 parts, or any combination thereof. When the weight percentage is less than 70, insufficient bicarbonate ions are released, making it difficult to effectively remove calcium and heavy metal ions from the wastewater. When the weight percentage is greater than 80, the bicarbonate ion concentration in the water may be too high, affecting the water quality. The core of the coated sodium bicarbonate is NaHCO3, and the coating material is polylactic acid (PLA). The coating weight gain is 15%.

[0036] The mass fraction of the nanoscale seed crystals can be any value or combination of 20, 22, 25, 28, or 30 parts. A mass fraction below 20 parts provides insufficient crystal nuclei for the precipitation reaction, resulting in low precipitation efficiency. A mass fraction above 30 parts may increase costs without significantly improving the precipitation effect. The nanoscale seed crystals are nanocalcite seed crystals with an average particle size of 50 nm.

[0037] The C agent induces crystallization by slowly releasing carbonate ions at the end, deeply stabilizes heavy metals and removes hardness, ensuring that the effluent meets the standards. The preparation method of C agent is as follows: NaHCO3 powder was placed in a fluidized bed granulator and coated with polylactic acid (PLA) dissolved in dichloromethane to create a 5% coating solution. The inlet air temperature was maintained at 40°C and the atomization pressure at 0.3 MPa. The fluidized NaHCO3 was spray-coated until the coating reached a 15% weight gain. This process ensured that the PLA film completely enveloped the NaHCO3. The coated NaHCO3 particles were then mixed with nanocalcite seed crystals in a gentle mixer for 5 minutes to prevent the coating from cracking. This yielded Agent C.

[0038] Biodegradable PLA film is used to precisely coat NaHCO3, achieving CO3 2- The delayed release of the drug allows its release profile to match the pollutant concentration and pH environment.

[0039] In this embodiment, the modified calcium-silicon-based mineral material in Agent A is sepiolite or diatomaceous earth loaded with nano-calcium oxide and iron salts; the structural modifier is disodium hydrogen phosphate or sodium dihydrogen phosphate; the organic flocculant is zwitterionic polyacrylamide; and the inorganic flocculant is polyferric silicate sulfate. The sepiolite or diatomaceous earth loaded with nano-calcium oxide and iron salts, due to its unique microstructure and chemical properties, serves as an important foundation for the adsorption and removal of pollutants from wastewater. Nano-calcium oxide has a strong alkalinity, which can neutralize some acidic substances in wastewater and promote the precipitation of some metal ions. During hydrolysis, the iron salts form ferric hydroxide colloids with adsorption and coagulation properties, further enhancing their ability to capture fine particles and organic matter in wastewater. Zwitterionic polyacrylamide, as an organic flocculant, carries both positive and negative ionic groups on its molecular chain. In wastewater, it can bring differently charged pollutant particles closer together and agglomerate into larger flocs through charge neutralization, bridging, and adsorption. This flocculation effect is unaffected by wastewater pH and operates over a wide pH range, demonstrating strong adaptability. Polyferric silicate sulfate, an inorganic flocculant, produces a hydrolysis product with a high degree of polymerization and positive charge density. On the one hand, it electrically neutralizes colloidal particles in wastewater, reducing surface charge repulsion and promoting particle collision and coagulation. On the other hand, the polymers it forms can connect multiple particles through adsorption and bridging, forming larger flocs. When used synergistically with organic flocculants, they leverage the advantages of both, enhancing flocculation efficiency and effectiveness. Disodium hydrogen phosphate or sodium dihydrogen phosphate, acting as structure regulators, regulate floc structure during floc formation. They form complexes with metal ions, modifying the surface properties and internal structure of flocs, making them denser and more stable. Dense flocs have better settling properties during sedimentation, enabling faster separation from wastewater, thereby improving sedimentation efficiency and effluent quality. These components work together to enable Agent A to effectively remove suspended solids, colloids, and some organic matter from wastewater during primary treatment. The adsorption of the modified calcium-silicon-based mineral material provides the foundation for the subsequent flocculation process. The synergistic effect of the organic and inorganic flocculants rapidly aggregates pollutant particles into flocs, while the structure regulator ensures that the flocs have good settling properties. Through this combined action, Agent A significantly reduces wastewater turbidity and COD, creating favorable conditions for subsequent biochemical and advanced treatment. Furthermore, this combined formulation exhibits excellent adaptability and stability across diverse water qualities and treatment conditions, meeting the needs of a wide range of wastewater treatment scenarios. In this example, the trace element mixture in Agent B includes 1-3% CuSO4·5H2O, 2-4% ZnSO4·7H2O, 1-2% Na2MoO4·2H2O, 0.3-0.8% CoCl2·6H2O, and 90-95% zeolite powder carrier. The nitrification promoter is a mixture of ammonium chloride and urea in a mass ratio of 1:0.8-1.2. The binder is sodium carboxymethyl cellulose. Trace elements such as CuSO4·5H2O, ZnSO4·7H2O, Na2MoO4·2H2O, and CoCl2·6H2O are components or activators of various enzymes in microorganisms and participate in various microbial physiological processes, such as energy metabolism and biosynthesis. The zeolite powder carrier not only supports these trace elements but also has a large specific surface area and ion exchange properties, enabling it to adsorb and exchange harmful substances in wastewater while providing a habitat for microorganisms to attach and grow. A nitrification promoter, a mixture of ammonium chloride and urea in a mass ratio of 1:0.8-1.2, provides a suitable nitrogen source for nitrifying bacteria, promoting the nitrification reaction. In a biochemical system, nitrifying bacteria convert ammonia nitrogen into nitrite and nitrate, a process crucial for removing ammonia nitrogen from wastewater. A suitable ratio of ammonium chloride and urea can meet the nitrogen source requirements of nitrifying bacteria at different growth stages, improving ammonia nitrogen removal efficiency. Sodium carboxymethyl cellulose acts as a binder, binding the tea seed meal extract microcapsules, carbon source, trace element mixture, and nitrification promoter together to form a granular Agent B with sufficient strength and stability. This not only facilitates the storage, transportation, and use of Agent B, but also allows for controlled release of its components. In a biochemical system, Agent B slowly releases its components, enabling precise control of the bacterial colony structure.

[0040] Agent B, through the synergistic action of its components, precisely regulates the biochemical system's bacterial colony structure and inhibits the growth of filamentous bacteria. Excessive growth of filamentous bacteria in a biochemical system can lead to sludge bulking, affecting system stability and treatment effectiveness. Tea saponins in tea seed meal extract microcapsules regulate the microbial growth environment, inhibiting the growth of filamentous bacteria while providing suitable growth conditions for beneficial microorganisms. Furthermore, Agent B provides a slow-release carbon source and trace elements, ensuring a stable nutrient supply for microorganisms throughout the treatment process, enhancing the system's stability and resilience. Agent B exerts its unique effect under varying water quality and treatment load conditions, improving the biochemical system's removal of organic matter and ammonia nitrogen, and further enhancing the quality of wastewater treatment. Agent C plays a vital role in the final stage of sewage treatment. Coated sodium bicarbonate is one of the main components of Agent C. Its coating material, polylactic acid (PLA), is biodegradable, which not only conforms to the concept of environmental protection, but also can achieve CO3 2-When Agent C is added to sewage, over time, the PLA coating is gradually decomposed by microorganisms in the environment, causing the core NaHCO3 to begin to release bicarbonate ions (HCO3 - These bicarbonate ions will react with calcium ions (Ca 2+ ) reacts to form calcium carbonate (CaCO3) precipitation. The specific reaction formula is: Ca 2+ + 2HCO3 - ⇌CaCO3↓ + H2O + CO2↑. Through this precipitation reaction, the concentration of calcium ions in the wastewater is effectively reduced, thereby reducing the hardness of the water.

[0041] At the same time, for heavy metal ions in wastewater, such as lead ions (Pb 2+ ), copper ions (Cu 2+ ), bicarbonate ions undergo a series of chemical reactions with these, producing corresponding carbonate precipitates. Nanoscale seeds, also known as nanocalcite seeds, have tiny particles with an average diameter of 50 nm. Their unique particle size and crystal structure provide a large number of crystal nuclei for the precipitation reaction. When the tiny particles generated by the precipitation reaction encounter the nanoscale seeds, they quickly adhere to the surface of the seeds and grow according to the seeds' crystal structure, forming larger, more stable precipitate particles. These precipitate particles have improved settling properties, enabling faster separation from wastewater, thereby achieving deep, stable removal of heavy metal ions.

[0042] Moreover, due to the PLA coating, CO3 2- The delayed release of bicarbonate ions allows the release curve of bicarbonate ions to match the pollutant concentration and pH environment. When the pollutant concentration in the sewage is high and the pH value is suitable for the reaction, bicarbonate ions can be released continuously and stably, ensuring the efficient progress of the precipitation reaction. At the same time, this delayed release avoids the one-time large-scale release of bicarbonate ions, preventing the occurrence of excessive bicarbonate ion concentration in the water affecting the water quality. Agent C induces crystallization by slowly releasing carbonate at the end, deeply stabilizes heavy metals and removes hardness, ensuring that the effluent meets the relevant water quality standards and drawing a perfect end to the entire sewage treatment process. In sewage of different types and concentrations, Agent C can exert good treatment effects by virtue of its unique principle of action, providing reliable protection for sewage treatment. An embodiment of the second aspect of the present invention provides a sewage treatment method using the composite sewage treatment agent, comprising the following steps: (1) Add agent A to the industrial wastewater to be treated to carry out coagulation and sedimentation reaction to complete the primary treatment; (2) introducing the effluent from step (1) into a biochemical treatment unit and adding agent B thereto for bioaugmentation treatment; (3) Add Agent C to the effluent of step (2), stir and react, and precipitate to complete the deep treatment.

[0043] In this example, the wastewater treatment equipment includes a regulating tank, an intelligent dosing system, a primary flocculation and sedimentation tank, an A / O biochemical tank, a secondary sedimentation tank, and a clear water tank. An online UV-VIS spectroscopic sensor and an ion-selective electrode are installed at the regulating tank inlet to monitor COD, TOC, color, and the concentrations of specific heavy metals (such as Cu and Cr) in real time.

[0044] In step (1), wastewater is pumped from the regulating tank into the primary reaction tank (divided into three compartments: fast mixing, medium speed, and slow mixing).

[0045] Fast mixing: Add agent A and control the stirring intensity (G value) at 250-350 s -1 , the hydraulic retention time (HRT) is 2 minutes.

[0046] Medium speed: G-force drops to 70-90 s -1 , HRT is 5 minutes.

[0047] Slow mixed grid: G value drops to 20-40 s -1 , HRT is 10 minutes.

[0048] Then it enters the inclined plate sedimentation tank, and the surface load is 1.0 m 3 / m 2 h. The settled sludge is discharged into the sludge storage tank, and the supernatant from the primary sedimentation tank enters the A / O biochemical tank.

[0049] In this embodiment, the A / O biochemical pool includes an anoxic pool (A pool) and an aerobic pool (O pool).

[0050] Anoxic tank (tank A): HRT = 2h, dissolved oxygen (DO) < 0.5 mg / L. At the head end of this tank, Agent B is continuously added via a dry powder dosing machine at a mass ratio of Agent B to influent COD = 1:50-200.

[0051] Aerobic pool (O pool): HRT=6h, DO controlled at 2-3 mg / L.

[0052] Mixed liquid reflux ratio: 100%-200%. The biochemical effluent enters the secondary reaction tank (slow mixing tank).

[0053] In this embodiment, according to the pH value of the effluent (usually 7.0-7.5) and the hardness online monitoring value, the residual Ca 2+ Add agent C at a ratio of (1.0-1.5):1 and the reaction stirring intensity G is 15-25 s -1 , HRT is 20 minutes.

[0054] Then it enters the final sedimentation tank (surface load 0.8 m 3 / m 2 h) to completely separate the generated microcrystalline particles. The clear supernatant that meets the standards will overflow into the clean water tank for discharge or reuse.

[0055] The sludge from the primary and secondary sedimentation tanks is combined and sent to the sludge thickening tank.

[0056] The third aspect of the present application provides an application of the composite sewage treatment agent in sewage treatment.

[0057] When treating industrial wastewater containing high concentrations of suspended solids, colloids, and organic matter, Agent A can rapidly reduce wastewater turbidity and COD, reducing the burden on subsequent treatment. Agent B plays a key role in the biochemical treatment unit. For example, printing and dyeing wastewater, with its complex composition and high concentrations of organic and color substances, presents significant challenges for biochemical treatment. The synergistic effects of Agent B, including tea seed meal extract microcapsules, a carbon source, a trace element mixture, and a nitrification promoter, precisely regulate the biochemical system's bacterial structure, inhibit the growth of filamentous bacteria, and prevent sludge bulking. Furthermore, they provide a stable nutrient supply for microorganisms, enhance the system's stability and shock resistance, and improve the biochemical system's removal of organic matter and ammonia nitrogen. Agent C is indispensable in the advanced treatment stage. For mining wastewater containing high hardness and heavy metal ions, the coated sodium bicarbonate in Agent C slowly releases carbonate ions, which react with calcium and heavy metal ions to form a precipitate. Nano-sized seed crystals provide the crystal nuclei for the precipitation reaction, resulting in larger and more stable precipitate particles. This effectively reduces water hardness and removes heavy metal ions, ensuring that effluent meets standards. The composite sewage treatment agent and sewage treatment method are applicable to various types of industrial wastewater treatment and have broad application prospects.

[0058] Example The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight. Unless otherwise stated, all reagents used in the examples are available through conventional commercial sources or synthesized according to conventional methods and can be used directly without further processing. Unless otherwise stated, all instruments used in the examples are available through conventional commercial sources.

[0059] Preparation Example 1 A composite sewage treatment agent, comprising agent A, agent B and agent C, wherein The agent A comprises the following raw materials in mass fraction: 50 parts of modified calcium-silicon-based mineral material, 15 parts of zwitterionic polyacrylamide, 8 parts of disodium hydrogen phosphate, 7 parts of polysilicate ferric sulfate, and 25 parts of anhydrous sodium sulfate; The agent B comprises the following raw materials in mass fraction: 40 parts of tea seed meal extract microcapsules, 30 parts of carbon source (starch and glucose), 15 parts of trace element mixture, 12 parts of nitration promoter, and 5 parts of sodium carboxymethyl cellulose; The agent C comprises the following raw materials in mass fraction: 75 parts of coated sodium bicarbonate and 25 parts of nano-calcite seed crystals.

[0060] Preparation Example 2 A composite sewage treatment agent, comprising agent A, agent B and agent C, wherein The agent A comprises the following raw materials in mass fraction: 42 parts of modified calcium-silicon-based mineral material, 13 parts of zwitterionic polyacrylamide, 6 parts of disodium hydrogen phosphate, 9 parts of polysilicate ferric sulfate, and 30 parts of anhydrous sodium sulfate; The agent B comprises the following raw materials in mass fraction: 32 parts of tea seed meal extract microcapsules, 23 parts of carbon source (starch and glucose), 11 parts of trace element mixture, 14 parts of nitration promoter, and 7 parts of sodium carboxymethyl cellulose; The agent C comprises the following raw materials in mass fraction: 70 parts of coated sodium bicarbonate and 30 parts of nano-calcite seed crystals.

[0061] Preparation Example 3 A composite sewage treatment agent, comprising agent A, agent B and agent C, wherein The agent A comprises the following raw materials in mass fraction: 60 parts of modified calcium silicate mineral material, 18 parts of zwitterionic polyacrylamide, 8 parts of disodium hydrogen phosphate, 5 parts of polysilicate ferric sulfate, and 22 parts of anhydrous sodium sulfate; The agent B comprises the following raw materials in mass fraction: 50 parts of tea seed meal extract microcapsules, 38 parts of carbon source (starch and glucose), 18 parts of trace element mixture, 5 parts of nitration promoter, and 3 parts of sodium carboxymethyl cellulose; The agent C comprises the following raw materials in mass fraction: 80 parts of coated sodium bicarbonate and 20 parts of nano-calcite seed crystals.

[0062] The following examples were all tested using actual comprehensive wastewater collected from an industrial park in Changsha. The main water quality indicators were: COD: 850-900 mg / L, NH3-N: 65-70 mg / L, chromaticity: 350-400 times, Cr 3+ : 2.5-2.8mg / L, Cd 2+ : 0.7-0.9mg / L, pH: 7.5-8.5.

[0063] Example 1 Five 1L portions of raw water were added with 100, 200, 300, 400, and 500 mg / L of Agent A from Preparation Example 1, respectively. The mixture was stirred rapidly (300 rpm / 2 min), then moderately (80 rpm / 5 min), and then slowly (40 rpm / 10 min), allowing it to settle for 30 min. The supernatant was collected and tested for COD, color, and heavy metal concentration. The results are shown in Table 1:

[0064] As shown in Table 1, when the dosage of Agent A is 300 mg / L, the removal rate curve has entered a plateau phase, and further increasing the dosage is cost-effective. Therefore, the optimal dosage is 300 mg / L.

[0065] Example 2 Five portions of the supernatant treated with Example 1 (300 mg / L Agent B) were added to an equal amount of activated sludge, and 0, 5, 10, 15, and 20 mg / L Agent B (calculated as Agent B dry weight / influent COD) were added, respectively. After 8 hours of reaction in the A / O system, the COD and NH₃-N levels in the water were measured. The results are shown in Table 2:

[0066] As shown in Table 2, Agent B effectively increased biochemical efficiency and improved sludge properties. The optimal dosage was 10 mg / L.

[0067] Example 3 Take 5 parts of the effluent treated in Example 2 (Agent B 10 mg / L) and calculate the concentration of n(HCO 3- ):n(Ca 2+ +M 2+ ) was 0.8:1, 1.0:1, 1.2:1, 1.5:1, 2.0:1, and Agent C was added. After slow stirring (25 rpm / 20 min), the supernatant was precipitated and the residual hardness, heavy metals, and turbidity were measured. The results are shown in Table 3:

[0068] From Table 3, we can see that when the molar ratio is 1.2:1, the pollutants have been deeply removed. The optimal molar ratio is 1.2:1.

[0069] Example 4 Take 1L of raw water and follow the steps of Agent A (300mg / L) → precipitation → Agent B (10mg / L) + A / O biochemical (8h) → Agent C (n(HCO3 - ):n(ion)=1.2:1) → Complete precipitation process. The final effluent indicators were tested, and the results are shown in Table 4:

[0070] Comparative Example 1 Take 1L of raw water, add 300mg / L PAC + 5mg / L PAM, after flocculation and sedimentation, the supernatant enters the A / O system for treatment for 8h (without adding agent B). After sedimentation, the supernatant is taken for detection. The results are shown in Table 5.

[0071]

[0072] Comparative Example 2 Take 1L of raw water and treat it according to the process of Agent A (300mg / L) → Precipitation → Agent C (1.2:1) → Precipitation (skip the biochemical unit).

[0073] Results: COD effluent was 105 mg / L, and NH3-N effluent was 55 mg / L.

[0074] Analysis: NH3-N was virtually completely removed, demonstrating that Agent B and the biochemical processes it drives are essential for removing biodegradable pollutants such as ammonia nitrogen. This may be due to the tea seed meal extract microcapsules, carbon source, trace element mixture, and nitrification accelerator in Agent B, which provide a suitable growth environment and abundant nutrients for microorganisms, promoting their metabolic activity and effectively removing biodegradable pollutants like ammonia nitrogen. In Comparative Example 2, however, because the biochemical treatment unit, where Agent B is added, was omitted, the lack of microbial activity prevented the full decomposition and removal of pollutants like ammonia nitrogen.

[0075] The overall test results of the composite sewage treatment agent and treatment method of the present invention demonstrate significant advantages in treating industrial wastewater. Compared with traditional treatment agents (such as PAC and PAM in Comparative Example 1), the composite sewage treatment agent of the present invention can more efficiently remove a variety of pollutants from wastewater, including COD, ammonia nitrogen, chroma, heavy metals, etc., and the treated effluent water quality is more able to meet national standards. At the same time, each agent plays a unique and critical role in different treatment stages. The coagulation and sedimentation of Agent A reduces the load for subsequent treatment, the bio-augmentation treatment of Agent B improves biochemical efficiency and sludge properties, and the deep treatment of Agent C ensures that the effluent meets discharge standards.

[0076] Comparative Example 3 The treatment process was as follows: Agent A (300 mg / L) → precipitation → Agent B (10 mg / L) + A / O biochemical treatment (8 h).

[0077] Results: Effluent Cd 2+ The concentration is 0.09 mg / L, and the total hardness is relatively high.

[0078] Analysis: Effluent Cd 2+The concentration exceeded the standard, and the hardness was not effectively removed. It was proved that Agent C is crucial for the deep removal of heavy metals and hardness. The reason may be that the coated sodium bicarbonate in Agent C can slowly release carbonate, reacting with calcium ions and heavy metal ions such as cadmium ions in the wastewater to form precipitates, and the nano-calcite seeds provide a crystallization core for the precipitation reaction, making the generated precipitate particles larger and more stable, thereby effectively reducing the hardness of the water and removing heavy metal ions. In Comparative Example 3, since Agent C was not used for deep treatment, the cadmium ions and hardness in the wastewater could not be fully removed, resulting in the cadmium ion concentration of the effluent exceeding the standard and the total hardness being high.

[0079] It can be further seen from the results of the above multiple embodiments and comparative examples that the composite sewage treatment agents A, B and C of the present invention are indispensable. They cooperate with each other at different stages of sewage treatment and work together to form a complete and efficient sewage treatment system. Comparative Example 4 Take 1L of raw water, add agent A (300mg / L), agent B (10mg / L), and agent C (1.2:1) at the same time at the beginning of rapid mixing, and the subsequent process is the same as Example 4.

[0080] Results: The treatment effect decreased overall, COD effluent 85 mg / L, NH3-N effluent 22 mg / L, Cd 2+ The effluent is 0.15mg / L.

[0081] Analysis: Simultaneous addition leads to interference in drug efficacy (e.g. premature release of CO3 by Agent C 2- Encapsulated by flocculation; Agent B is removed by flocculation).

[0082] Comparative Example 5 An equal amount of ordinary tea seed meal powder was used to replace the B-type microcapsules in Example 4, and the other steps were exactly the same.

[0083] Results: The COD removal rate of the biochemical system was acceptable at the beginning, but after 24 hours of operation, the microbial activity was significantly inhibited and the NH3-N removal rate dropped below 60%.

[0084] Analysis: Unencapsulated tea seed meal powder instantly releases high concentrations of saponins, impacting and even toxic the microbial community. This demonstrates the importance of microencapsulation technology for achieving sustained release and biocompatibility.

[0085] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A composite sewage treatment agent, characterized in that: Including dose A, dose B and dose C, The agent A comprises the following raw materials in mass fraction: 40-60 parts of modified calcium-silicon-based mineral material, 10-20 parts of organic flocculant, 5-10 parts of structure regulator, 5-10 parts of inorganic flocculant, and 20-30 parts of filler; The agent B comprises the following raw materials in mass fraction: 30-50 parts of tea seed meal extract microcapsules, 20-40 parts of carbon source, 10-20 parts of trace element mixture, 5-15 parts of nitration promoter, and 3-8 parts of binder; The agent C comprises the following raw materials in mass fraction: 70-80 parts of coated sodium bicarbonate and 20-30 parts of nano-sized seed crystals.

2. The composite sewage treatment agent according to claim 1, characterized in that The modified calcium-silicon-based mineral material in the agent A is sepiolite or diatomaceous earth loaded with nano-calcium oxide and iron salt; and / or The structure regulator is disodium hydrogen phosphate or sodium dihydrogen phosphate; and / or The organic flocculant is a zwitterionic polyacrylamide; and / or The inorganic flocculant is polysilicate ferric sulfate.

3. The composite sewage treating agent according to claim 1, characterized in that The preparation method of the tea seed meal extract microcapsules in the agent B is: using the sharp hole-coagulation bath method, dripping a core material solution containing sodium alginate and tea seed meal extract into a coagulation bath containing calcium ions and chitosan to form gel microcapsules.

4. The composite sewage treating agent according to claim 1, characterized in that The trace element mixture in the agent B includes CuSO4·5H2O 1-3%, ZnSO4·7H2O 2-4%, Na2MoO4·2H2O 1-2%, CoCl2·6H2O 0.3-0.8%, and zeolite powder carrier 90-95%; and / or The nitration accelerator is a mixture of ammonium chloride and urea in a mass ratio of 1:0.8-1.2; and / or The binder is sodium carboxymethyl cellulose.

5. The composite sewage treating agent according to claim 1, characterized in that The preparation method of the coated sodium bicarbonate in the agent C is: using a solution of a biodegradable polymer material as a coating liquid, coating sodium bicarbonate particles, and controlling the coating weight gain to be 10%-20%.

6. A sewage treatment method using the composite sewage treatment agent according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Add agent A to the industrial wastewater to be treated to carry out coagulation and sedimentation reaction to complete the primary treatment; (2) introducing the effluent from step (1) into a biochemical treatment unit and adding agent B thereto for bioaugmentation treatment; (3) Add Agent C to the effluent of step (2), stir and react, and precipitate to complete the deep treatment.

7. The sewage treatment method using the composite sewage treatment agent according to claim 6, characterized in that: In step (1), after adding agent A, the -1 , 70-90s -1 and 20-40 s -1 The three-stage reaction is carried out by stirring with a stirring intensity G value of .

8. The sewage treatment method using the composite sewage treatment agent according to claim 6, characterized in that: The agent B is added to the anoxic zone or the water inlet of the biochemical treatment unit at a mass ratio of agent B to influent COD of 1:50-200.

9. The sewage treatment method using the composite sewage treatment agent according to claim 6, characterized in that: The dosage of the agent C is controlled according to the molar ratio of bicarbonate to residual calcium ions and heavy metal ions in the wastewater (1.0-1.5):1, and the reaction stirring intensity G value is 15-25 s -1 .

10. Use of the composite sewage treatment agent according to any one of claims 1 to 5 in sewage treatment.

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