Wastewater treatment composition and preparation method thereof

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a wastewater treatment composition and a preparation method thereof. The wastewater treatment composition is prepared from the following raw materials: steel slag powder, a fly ash-zeolite complex, modified montmorillonite, lignosulfonate and SRB sulfate reducing bacteria, wherein the fly ash-zeolite complex is prepared by carrying out hydrothermal reaction on fly ash and natural clinoptilolite according to a certain proportion, and the modified montmorillonite is prepared by firstly loading sodium sulfate and then modifying with quaternary ammonium salt. The wastewater treatment composition prepared by the invention realizes deep removal of heavy metal ions, efficient treatment of organic matters and suspended matters, release control of hydrogen sulfide gas and pH adjustment of acidic wastewater through multi-mechanism synergy of various components, and has the advantages of environmental friendliness, low cost and high universality.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and particularly relates to a wastewater treatment composition and a preparation method thereof. Background Art

[0002] With the rapid development of industry, the wastewater discharged from industries such as electroplating, chemical engineering, and mining often contains various pollutants, such as heavy metal ions (Pb 2+ , Cu 2+ , Cd 2+ , etc.), high-concentration organic matter (COD), and suspended solids, which seriously threaten the ecological environment and human health. At present, wastewater treatment technologies mainly include chemical precipitation method, adsorption method, biological treatment method, etc., but there are still many problems to be solved urgently: 1. Insufficient depth and stability of heavy metal removal: The traditional chemical precipitation method relies on hydroxide precipitation, which requires strict control of pH and is prone to generate a large amount of sludge; single adsorption materials (such as fly ash, zeolite) have single adsorption sites and poor selectivity, and have low removal efficiency for complexed heavy metals, especially the adsorption capacity significantly decreases in an acidic environment.

[0003] 2. Secondary pollution problem in the application of sulfate-reducing bacteria (SRB): SRB generates S by reducing sulfate 2- , which can form sulfide precipitates with heavy metals. However, if the release of sulfate gets out of control during its metabolic process, it is easy to cause a large amount of hydrogen sulfide gas to be generated, resulting in malodor pollution and safety hazards; at the same time, the existing technology lacks effective regulation of the sulfate release rate, and it is difficult to achieve the synergistic optimization of SRB metabolism and heavy metal precipitation.

[0004] 3. Lack of synergistic mechanism for the removal of organic matter and suspended solids: The treatment of high-COD wastewater often relies on the simple combination of biodegradation and chemical flocculation, lacking efficient synergistic effects. Biological treatment is easily affected by water quality fluctuations, and chemical flocculants (such as polyaluminum chloride) have high costs and may introduce secondary pollutants, making it difficult to balance the COD removal rate and turbidity removal efficiency. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a wastewater treatment composition and a preparation method thereof to solve the problems of low removal efficiency, secondary pollution, high cost, etc. in the traditional wastewater treatment process.

[0006] Based on the above purpose, the present invention provides a wastewater treatment composition, including the following raw materials in parts by weight: steel slag powder: 30 - 40 parts, fly ash-zeolite complex: 20 - 30 parts, modified montmorillonite: 10 - 15 parts, lignosulfonate: 5 - 10 parts, SRB sulfate-reducing bacteria: 1 - 5 parts; The preparation process of the fly ash-zeolite composite is as follows: Fly ash and natural clinoptilolite are added to an alkaline solution, and the temperature is raised to 75-85°C with stirring, and the reaction is carried out for 1-3 hours. After cooling to room temperature, centrifugation is performed, and the solid is washed with deionized water until the pH is neutral, dried, ground, and passed through a 150-250 mesh sieve to obtain the fly ash-zeolite composite; The preparation process of the modified montmorillonite is as follows: Sodium-based montmorillonite is added to dilute hydrochloric acid, ultrasonicated for 30-50 minutes, filtered, washed with deionized water until neutral, dried and ground, passed through a 100-200 mesh sieve, then added to a sodium sulfate solution, the temperature is raised to 50-60°C and ultrasonicated for 20-40 minutes, and then reacted with stirring for 1-3 hours. After filtration, washing, drying, and grinding, it is passed through a 100-200 mesh sieve. Finally, it is added to a cetyltrimethylammonium bromide solution, and stirred and reacted at room temperature for 40-60 minutes. After filtration, washing, and drying, it is passed through a 100-200 mesh sieve to obtain the modified montmorillonite.

[0007] Preferably, the particle size of the steel slag powder is 80-120 mesh.

[0008] Preferably, the lignosulfonate refers to sodium lignosulfonate or potassium lignosulfonate.

[0009] Preferably, in the preparation process of the fly ash-zeolite composite, the weight ratio of fly ash, natural clinoptilolite and alkaline solution is 1:1:3-7, and the alkaline solution refers to an aqueous sodium hydroxide solution with a concentration of 5 mol / L.

[0010] Preferably, in the preparation process of the modified montmorillonite, the weight ratio of sodium-based montmorillonite, dilute hydrochloric acid, sodium sulfate solution and cetyltrimethylammonium bromide solution is 1:8-12:10-20:10-20.

[0011] Preferably, the dilute hydrochloric acid in the preparation process of the modified montmorillonite refers to a hydrochloric acid solution with a concentration of 10%.

[0012] Preferably, the sodium sulfate solution in the preparation process of the modified montmorillonite refers to a sodium sulfate solution with a concentration of 5%.

[0013] Preferably, the cetyltrimethylammonium bromide solution in the preparation process of the modified montmorillonite refers to a cetyltrimethylammonium bromide solution with a concentration of 10%.

[0014] Preferably, the purpose of the modified montmorillonite is to achieve a slow-release effect of sodium sulfate. This is mainly because the hydrophobic long chains of cetyltrimethylammonium bromide form a barrier-like structure between the montmorillonite layers. When the montmorillonite containing sodium sulfate is in an aqueous solution environment, water molecules and other solute molecules need to overcome the obstruction of the hydrophobic long chains to enter the montmorillonite layers and contact sodium sulfate. This makes the process of sodium sulfate released from the montmorillonite layers to the external solution slow, thus achieving the slow-release effect. At the same time, between the montmorillonite layers, the diffusion of SO 4 2− and Na + is also restricted. The presence of the hydrophobic long chains reduces the free space between the layers and decreases the diffusion coefficient of ions. Ions need to slowly diffuse through the gaps of the hydrophobic long chains to be released from the montmorillonite layers, further prolonging the release time.

[0015] Furthermore, the present invention also provides a preparation method of the above wastewater treatment composition, which specifically includes the following steps: S1. Add steel slag powder to dilute hydrochloric acid, stir at room temperature for 30 - 50 min, filter, wash with deionized water until the pH is neutral, and obtain purified steel slag powder after drying; S2. Mix the purified steel slag powder, fly ash - zeolite complex, modified montmorillonite, lignosulfonate, and SRB sulfate-reducing bacteria, add them to a ball mill, mix for 10 - 20 min, and obtain a wastewater treatment composition after passing through a 100 - 200 mesh sieve.

[0016] Preferably, the weight ratio of steel slag powder to dilute hydrochloric acid in S1 is 1:5 - 10.

[0017] Preferably, the dilute hydrochloric acid in S1 refers to a hydrochloric acid solution with a concentration of 10%.

[0018] Preferably, the action mechanism of SRB sulfate-reducing bacteria is: Organic matter + SO 4 2- + SRB → S 2- + CO 2 ↑ + H 2 O 2M n+ + nS 2- → M 2 S n ↓, where M n+ represents heavy metal ions.

[0019] The beneficial effects of the present invention: 1. Through the synergistic effect of the triple mechanisms of "bioreduction - composite adsorption - chemical precipitation", the present invention achieves the efficient removal of heavy metal ions. Modified montmorillonite is loaded with sodium sulfate and modified with cetyltrimethylammonium bromide to form an interlayer hydrophobic barrier structure, which controllably releases sulfate for SRB metabolism to generate S 2- , which generates sulfide precipitates with extremely low solubility products with heavy metal ions, fundamentally reducing the ion concentration. At the same time, the slow release of sulfate is used to inhibit the S 2- metabolic conversion efficiency of reducing bacteria, enabling sufficient reaction precipitation time with heavy metals, and avoiding the defects of H 2 S volatilization and relatively low heavy metal sedimentation efficiency existing in the anaerobic ponds using reducing bacteria; after alkaline co - treatment, the fly ash - zeolite composite activates the active sites of aluminosilicates, combines the molecular sieve effect of zeolite and the porous adsorption ability of fly ash to form an adsorbent. In high - concentration metal - ion wastewater, the adsorbent is saturated by adsorption (because the concentration is high, the adsorbent is easily saturated by adsorption). After adsorption saturation, with the metabolism of reducing bacteria, due to the concentration difference, the adsorbent continuously releases new heavy metal ions for precipitation near the microbial community or the adsorbent. The process is an equilibrium reaction of adsorbent adsorption - desorption equilibrium and continuous production of S 2- by reducing bacteria, thereby generating precipitation; steel slag powder adjusts the pH to neutral, promotes the precipitation of heavy metal hydroxides and provides a suitable environment for the flocculation reaction. This system breaks through the limitations of single - material adsorption or chemical precipitation, realizes the broad - spectrum and efficient removal of multiple heavy metals, and reduces the generation of sludge and the risk of secondary pollution.

[0020] 2. For high and high - turbidity wastewater, the present invention constructs a multi - stage treatment system of "biodegradation - adsorption enrichment - flocculation sedimentation". Metabolizing with organic matter as the carbon source, decomposes macromolecular organic matter into and , reducing from the source; the fly ash - zeolite composite and modified montmorillonite capture dissolved and colloidal organic matter through porous structures and interlayer adsorption, especially having excellent removal effects on refractory pollutants; lignosulfonate, as a natural polymer flocculant, under the synergistic action of , ions provided by steel slag powder, aggregates suspended solids into large flocs for rapid sedimentation through charge neutralization and bridging effects. This synergistic mechanism does not require additional chemical agents, has strong adaptability to water quality fluctuations, significantly improves the organic matter removal rate and turbidity removal efficiency, and reduces the treatment cost.

[0021] 3. Through material modification and process optimization, the present invention effectively solves the problems of hydrogen sulfide gas release and chemical agent residue in the traditional SRB process. Traditional montmorillonite generally utilizes its adsorption function in wastewater treatment, while the modified montmorillonite prepared in the present invention utilizes the sulfates loaded thereon to achieve a slow-release characteristic, enabling the release rate to match the metabolic rhythm of SRB, avoiding the explosive generation caused by a sudden increase in the substrate. At the same time, the sulfide precipitation reaction synchronously consumes , reducing gas volatilization; the resource utilization of industrial solid wastes such as steel slag powder and fly ash not only reduces the raw material cost, but also realizes "treating waste with waste" and reduces solid waste emissions; lignosulfonate, as a green flocculant, avoids the toxicity risk of synthetic polymer flocculants. The overall process does not introduce secondary pollutants, and the generation amount is extremely low, meeting the requirements of environmental protection and safe treatment, and is applicable to wastewater treatment scenarios sensitive to the environment. Specific Embodiments

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0023] The sources of the reagent raw materials used in the embodiments of the present invention are as follows: The steel slag powder is purchased from Banyi Mineral Products Processing Factory in Lingshou County, with a particle size of 80 - 120 mesh; the fly ash is purchased from Zhanteng Mineral Products Processing Factory in Lingshou County, with a purity of 99%; the natural clinoptilolite is purchased from Chifeng Huaqing Zeolite Processing Co., Ltd., with a particle size of 100 - 300 mesh; the sodium-based montmorillonite is purchased from Jiangsu Xianfeng Nano Materials Technology Co., Ltd., with a purity of 99%; the sodium lignosulfonate is purchased from Shanghai Macklin Biochemical Co., Ltd., with an Mw of 5000 - 10000; the potassium lignosulfonate is purchased from Tianjin Yezi Chemical Technology Co., Ltd., with a purity of 96%; the SRB sulfate-reducing bacteria are purchased from Shanghai Xuke Biotechnology Co., Ltd., with a purity of 100%; the cetyltrimethylammonium bromide is purchased from Shanghai Macklin Biochemical Co., Ltd., with a purity of 99%; the sodium sulfate is purchased from Shanghai Macklin Biochemical Co., Ltd., with a purity of 99%.

[0024] Example 1: A wastewater treatment composition and its preparation method, including the following process: (1) Add 3 Kg of fly ash and 3 Kg of natural clinoptilolite to 9 Kg of 5 mol / L sodium hydroxide, heat to 75°C with stirring, react for 1 h, cool to room temperature, then centrifuge. The solid is washed with deionized water until the pH is neutral, dried and ground, and then sieved through a 150-mesh sieve to obtain a fly ash-zeolite composite; (2) Add 3 Kg of sodium-based montmorillonite to 24 Kg of 10% dilute hydrochloric acid, sonicate for 30 min, filter, wash with deionized water until neutral, dry, grind, and pass through a 100-mesh sieve. Then add it to 30 Kg of 5% sodium sulfate solution, heat to 50 °C, sonicate for 20 min, and then react with stirring for 1 h. Filter, wash, dry, grind, and pass through a 100-mesh sieve. Finally, add it to 30 Kg of 10% cetyltrimethylammonium bromide solution, stir and react at room temperature for 40 min, filter, wash, dry, and pass through a 100-mesh sieve to obtain modified montmorillonite; (3) Add 7 Kg of steel slag powder to 35 Kg of 10% dilute hydrochloric acid, stir at room temperature for 30 min, filter, wash with deionized water until the pH is neutral, and dry to obtain purified steel slag powder; (4) Mix 6 Kg of purified steel slag powder, 4 Kg of fly ash-zeolite composite, 2 Kg of modified montmorillonite, 1 Kg of sodium lignosulfonate, and 200 g of SRB sulfate-reducing bacteria, add them to a ball mill, mix for 10 min, and pass through a 100-mesh sieve to obtain a wastewater treatment composition.

[0025] Example 2: A wastewater treatment composition and its preparation method, including the following process: (1) Add 3 Kg of fly ash and 3 Kg of natural clinoptilolite to 15 Kg of 5 mol / L sodium hydroxide solution, stir and heat to 80 °C, react for 2 h, cool to room temperature, centrifuge, wash the solid with deionized water until the pH is neutral, dry, grind, and pass through a 200-mesh sieve to obtain a fly ash-zeolite composite; (2) Add 3 Kg of sodium-based montmorillonite to 30 Kg of 10% dilute hydrochloric acid, sonicate for 40 min, filter, wash with deionized water until neutral, dry, grind, and pass through a 150-mesh sieve. Then add it to 45 Kg of 5% sodium sulfate solution, heat to 55 °C, sonicate for 30 min, and then react with stirring for 2 h. Filter, wash, dry, grind, and pass through a 150-mesh sieve. Finally, add it to 45 Kg of 10% cetyltrimethylammonium bromide solution, stir and react at room temperature for 50 min, filter, wash, dry, and pass through a 150-mesh sieve to obtain modified montmorillonite; (3) Add 8 Kg of steel slag powder to 60 Kg of 10% dilute hydrochloric acid, stir at room temperature for 40 min, filter, wash with deionized water until the pH is neutral, and dry to obtain purified steel slag powder; (4) Mix 7 Kg of purified steel slag powder, 5 Kg of fly ash-zeolite composite, 2.5 Kg of modified montmorillonite, 1.5 Kg of sodium lignosulfonate, and 500 g of SRB sulfate-reducing bacteria, add them to a ball mill, mix for 15 min, and pass through a 150-mesh sieve to obtain a wastewater treatment composition.

[0026] Example 3: A wastewater treatment composition and its preparation method, including the following process: (1) Add 4 Kg of fly ash and 4 Kg of natural clinoptilolite into 28 Kg of 5 mol / L sodium hydroxide solution, heat up to 85 °C with stirring, react for 3 h, after cooling to room temperature, centrifuge, wash the solid with deionized water until the pH is neutral, dry and then grind, and pass through a 250-mesh sieve to obtain a fly ash-zeolite composite; (2) Add 4 Kg of sodium-based montmorillonite into 48 Kg of 10% dilute hydrochloric acid, ultrasonicate for 50 min, filter, wash with deionized water until neutral, dry, grind and pass through a 200-mesh sieve, then add it into 80 Kg of 5% sodium sulfate solution, heat up to 60 °C and ultrasonicate for 40 min, then react with stirring for 3 h, filter, wash, dry, grind and pass through a 200-mesh sieve, finally add it into 80 Kg of 10% cetyltrimethylammonium bromide solution, stir and react at room temperature for 60 min, filter, wash, dry and pass through a 200-mesh sieve to obtain modified montmorillonite; (3) Add 9 Kg of steel slag powder into 90 Kg of 10% dilute hydrochloric acid, stir at room temperature for 50 min, filter, wash with deionized water until the pH is neutral, dry to obtain purified steel slag powder; (4) Mix 8 Kg of purified steel slag powder, 6 Kg of fly ash-zeolite composite, 3 Kg of modified montmorillonite, 2 Kg of lignosulfonate and 1 Kg of SRB sulfate-reducing bacteria, add them into a ball mill, mix for 20 min, and pass through a 200-mesh sieve to obtain a wastewater treatment composition.

[0027] Example 4: A wastewater treatment composition and its preparation method, including the following process: (1) Add 3 Kg of fly ash and 3 Kg of natural clinoptilolite into 15 Kg of 5 mol / L sodium hydroxide solution, heat up to 80 °C with stirring, react for 2 h, after cooling to room temperature, centrifuge, wash the solid with deionized water until the pH is neutral, dry and then grind, and pass through a 200-mesh sieve to obtain a fly ash-zeolite composite; (2) Add 3 Kg of sodium-based montmorillonite into 30 Kg of 10% dilute hydrochloric acid, ultrasonicate for 40 min, filter, wash with deionized water until neutral, dry, grind and pass through a 150-mesh sieve, then add it into 45 Kg of 5% sodium sulfate solution, heat up to 55 °C and ultrasonicate for 30 min, then react with stirring for 2 h, filter, wash, dry, grind and pass through a 150-mesh sieve, finally add it into 45 Kg of 10% cetyltrimethylammonium bromide solution, stir and react at room temperature for 50 min, filter, wash, dry and pass through a 150-mesh sieve to obtain modified montmorillonite; (3) Add 8 Kg of steel slag powder to 60 Kg of dilute hydrochloric acid with a concentration of 10%, stir at room temperature for 40 min, filter, wash with deionized water until the pH is neutral, and dry to obtain purified steel slag powder. (4) Mix 7 Kg of purified steel slag powder, 5 Kg of fly ash-zeolite composite, 2.5 Kg of modified montmorillonite, 1.5 Kg of lignosulfonate potassium, and 500 g of SRB sulfate-reducing bacteria, add them to a ball mill, mix for 15 min, and pass through a 150-mesh sieve to obtain a wastewater treatment composition.

[0028] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that sodium-based montmorillonite was not added to the cetyltrimethylammonium bromide solution. The specific preparation process is as follows: A wastewater treatment composition and its preparation method include the following processes: (1) Add 3 Kg of fly ash and 3 Kg of natural clinoptilolite to 15 Kg of 5 mol / L sodium hydroxide solution, heat to 80 °C with stirring, react for 2 h, cool to room temperature, centrifuge, wash the solid with deionized water until the pH is neutral, dry, grind, and pass through a 200-mesh sieve to obtain a fly ash-zeolite composite. (2) Add 3 Kg of sodium-based montmorillonite to 30 Kg of dilute hydrochloric acid with a concentration of 10%, ultrasonicate for 40 min, filter, wash with deionized water until neutral, dry, grind, and pass through a 150-mesh sieve. Then add it to 45 Kg of sodium sulfate solution with a concentration of 5%, heat to 55 °C and ultrasonicate for 30 min, then react with stirring for 2 h, filter, wash, dry, grind, and pass through a 150-mesh sieve to obtain modified montmorillonite. (3) Add 8 Kg of steel slag powder to 60 Kg of dilute hydrochloric acid with a concentration of 10%, stir at room temperature for 40 min, filter, wash with deionized water until the pH is neutral, and dry to obtain purified steel slag powder. (4) Mix 7 Kg of purified steel slag powder, 5 Kg of fly ash-zeolite composite, 2.5 Kg of modified montmorillonite, 1.5 Kg of sodium lignosulfonate, and 500 g of SRB sulfate-reducing bacteria, add them to a ball mill, mix for 15 min, and pass through a 150-mesh sieve to obtain a wastewater treatment composition.

[0029] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that sodium-based montmorillonite was first added to the cetyltrimethylammonium bromide solution and then added to the sodium sulfate solution. The specific preparation process is as follows: A wastewater treatment composition and its preparation method include the following processes: (1) Add 3 Kg of fly ash and 3 Kg of natural clinoptilolite to 15 Kg of 5 mol / L sodium hydroxide solution, heat to 80 °C with stirring, react for 2 h, cool to room temperature, centrifuge, wash the solid with deionized water until the pH is neutral, dry, grind, and pass through a 200-mesh sieve to obtain a fly ash-zeolite composite. (2) Add 3 Kg of sodium-based montmorillonite to 30 Kg of 10% dilute hydrochloric acid, ultrasonicate for 40 min, filter, wash with deionized water until neutral, dry, grind, and pass through a 150-mesh sieve. Then add it to 45 Kg of 10% cetyltrimethylammonium bromide solution, stir and react at room temperature for 50 min, filter, wash, dry, grind, and pass through a 150-mesh sieve. Finally, add it to 45 Kg of 5% sodium sulfate solution, heat to 55 °C, ultrasonicate for 30 min, then stir and react for 2 h, filter, wash, dry, and pass through a 150-mesh sieve to obtain modified montmorillonite; (3) Add 8 Kg of steel slag powder to 60 Kg of 10% dilute hydrochloric acid, stir at room temperature for 40 min, filter, wash with deionized water until the pH is neutral, and dry to obtain purified steel slag powder; (4) Mix 7 Kg of purified steel slag powder, 5 Kg of fly ash-zeolite composite, 2.5 Kg of modified montmorillonite, 1.5 Kg of sodium lignosulfonate, and 500 g of SRB sulfate-reducing bacteria, add them to a ball mill, mix for 15 min, and pass through a 150-mesh sieve to obtain a wastewater treatment composition.

[0030] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that sodium sulfate is not loaded on montmorillonite but is directly added as a component. The specific preparation process is as follows: A wastewater treatment composition and its preparation method include the following process: (1) Add 3 Kg of fly ash and 3 Kg of natural clinoptilolite to 15 Kg of 5 mol / L sodium hydroxide solution, stir and heat to 80 °C, react for 2 h, cool to room temperature, centrifuge, wash the solid with deionized water until the pH is neutral, dry, grind, and pass through a 200-mesh sieve to obtain a fly ash-zeolite composite; (2) Add 8 Kg of steel slag powder to 60 Kg of 10% dilute hydrochloric acid, stir at room temperature for 40 min, filter, wash with deionized water until the pH is neutral, and dry to obtain purified steel slag powder; (3) Mix 7 Kg of purified steel slag powder, 5 Kg of fly ash-zeolite composite, 2.5 Kg of sodium-based montmorillonite, 500 g of sodium sulfate, 1.5 Kg of sodium lignosulfonate, and 500 g of SRB sulfate-reducing bacteria, add them to a ball mill, mix for 15 min, and pass through a 150-mesh sieve to obtain a wastewater treatment composition.

[0031] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that the fly ash-zeolite composite is replaced with fly ash. The specific preparation process is as follows: A wastewater treatment composition and its preparation method include the following process: (1) Add 3 Kg of sodium-based montmorillonite to 30 Kg of dilute hydrochloric acid with a concentration of 10%, ultrasonicate for 40 min, filter, wash with deionized water until neutral, dry, grind, and pass through a 150-mesh sieve. Then add it to 45 Kg of sodium sulfate solution with a concentration of 5%, heat up to 55 °C, ultrasonicate for 30 min, and then react under stirring for 2 h. Filter, wash, dry, grind, and pass through a 150-mesh sieve. Finally, add it to 45 Kg of cetyltrimethylammonium bromide solution with a concentration of 10%, stir and react at room temperature for 50 min, filter, wash, dry, and pass through a 150-mesh sieve to obtain modified montmorillonite; (2) Add 8 Kg of steel slag powder to 60 Kg of dilute hydrochloric acid with a concentration of 10%, stir at room temperature for 40 min, filter, wash with deionized water until the pH is neutral, and dry to obtain purified steel slag powder; (3) Mix 7 Kg of purified steel slag powder, 5 Kg of fly ash, 2.5 Kg of modified montmorillonite, 1.5 Kg of sodium lignosulfonate, and 500 g of SRB sulfate-reducing bacteria, add them to a ball mill, mix for 15 min, and pass through a 150-mesh sieve to obtain a wastewater treatment composition.

[0032] Comparative Example 5: The difference between Comparative Example 5 and Example 2 is that the fly ash-zeolite complex is replaced by natural clinoptilolite. The specific preparation process is as follows: A wastewater treatment composition and its preparation method include the following processes: (1) Grind 6 Kg of natural clinoptilolite and pass through a 200-mesh sieve to obtain zeolite powder; (2) Add 3 Kg of sodium-based montmorillonite to 30 Kg of dilute hydrochloric acid with a concentration of 10%, ultrasonicate for 40 min, filter, wash with deionized water until neutral, dry, grind, and pass through a 150-mesh sieve. Then add it to 45 Kg of sodium sulfate solution with a concentration of 5%, heat up to 55 °C, ultrasonicate for 30 min, and then react under stirring for 2 h. Filter, wash, dry, grind, and pass through a 150-mesh sieve. Finally, add it to 45 Kg of cetyltrimethylammonium bromide solution with a concentration of 10%, stir and react at room temperature for 50 min, filter, wash, dry, and pass through a 150-mesh sieve to obtain modified montmorillonite; (3) Add 8 Kg of steel slag powder to 60 Kg of dilute hydrochloric acid with a concentration of 10%, stir at room temperature for 40 min, filter, wash with deionized water until the pH is neutral, and dry to obtain purified steel slag powder; (4) Mix 7 Kg of purified steel slag powder, 5 Kg of zeolite powder, 2.5 Kg of modified montmorillonite, 1.5 Kg of sodium lignosulfonate, and 500 g of SRB sulfate-reducing bacteria, add them to a ball mill, mix for 15 min, and pass through a 150-mesh sieve to obtain a wastewater treatment composition.

[0033] Comparative Example 6: The difference between Comparative Example 6 and Example 2 is that the addition amount of the purified steel slag powder is adjusted to 3 Kg.

[0034] Comparative Example 7: The difference between Comparative Example 7 and Example 2 is that the addition amount of the purified steel slag powder is adjusted to 5 Kg.

[0035] Comparative Example 8: The difference between Comparative Example 8 and Example 2 is that the addition amount of the purified steel slag powder is adjusted to 9 Kg.

[0036] Comparative Example 9: The difference between Comparative Example 9 and Example 2 is that the addition amount of the purified steel slag powder is adjusted to 11 Kg.

[0037] Comparative Example 10: The difference between Comparative Example 10 and Example 2 is that SRB sulfate-reducing bacteria are not added.

[0038] Performance test: Configure simulated wastewater containing Pb 2+ , Cu 2+ , Cd 2+ , Zn 2+ , Ni 2+ and other heavy metal ions with a total concentration of 150 mg / L; COD is 3000 mg / L; pH = 3; turbidity is 1000 NTU.

[0039] 1. Test of hydrogen sulfide gas concentration during wastewater treatment: Add the wastewater treatment compositions prepared in Examples 1-4 and Comparative Examples 1-10 to the wastewater already added to the anaerobic tank at a rate of 5 g per liter of wastewater, seal the anaerobic tank, evacuate the air with nitrogen, connect a hydrogen sulfide detector (model: Lubo LB-KS4X-S), maintain the temperature at 35 °C, the stirring speed at 150 rpm, and the reaction time at 72 h, and record the maximum hydrogen sulfide concentration. The experimental results are shown in Table 1.

[0040] 2. pH adjustment ability: Add the wastewater treatment compositions prepared in Examples 1-4 and Comparative Examples 1-10 to the wastewater at a rate of 5 g per liter of wastewater, stir for 30 min, and then measure the pH of the wastewater. The experimental results are shown in Table 1.

[0041] 3. Removal rate of heavy metal ions: Add the wastewater treatment compositions prepared in Examples 1-4 and Comparative Examples 1-10 to the wastewater already added to the anaerobic tank at a rate of 5 g per liter of wastewater, seal the anaerobic tank, evacuate the air with nitrogen, maintain the temperature at 35 °C, the stirring speed at 150 rpm, and the reaction time at 24 h. After centrifugation, measure the concentration of heavy metal ions in the supernatant and calculate the removal rate. The removal rate Q = , and the experimental results are shown in Table 1.

[0042] 4. Test of COD and turbidity removal effects: In the experiment for measuring the heavy metal removal rate, simultaneously measure the COD removal rate W = and turbidity removal rate Y = , and the experimental results are shown in Table 1.

[0043] Table 1 Performance Test

[0044] Data Analysis: It can be seen from the experimental data in Table 1 that the wastewater treatment composition prepared by the present invention in Examples 1-4 has significant advantages. It performs excellently in terms of heavy metal removal rate, can efficiently remove heavy metal ions in wastewater, and has strong removal ability for organic matter and suspended solids as can be seen from the COD removal rate and turbidity removal rate. Moreover, the concentration of hydrogen sulfide gas generated during the wastewater treatment process is extremely low, which is environmentally friendly. At the same time, it has good pH adjustment ability and can adjust the pH of the wastewater to near neutral. Among them, Example 2 has the best comprehensive performance, and all indicators are in the leading level among the examples, showing the best wastewater treatment effect.

[0045] It can be seen from the experimental data in Table 1 that compared with Comparative Examples 1-3, Example 2 has a significant advantage in the maximum hydrogen sulfide concentration. This may be because the modified montmorillonite in Example 2 is first loaded with sodium sulfate and then modified by cetyltrimethylammonium bromide. Its hydrophobic long chains form a barrier-like structure between the montmorillonite layers, significantly delaying the release rate of sodium sulfate. When the montmorillonite is in an aqueous solution, water molecules need to overcome the obstruction of the hydrophobic long chains to contact the sodium sulfate between the layers, enabling SO 4 2- and Na + to slowly diffuse into the solution, matching the metabolic rate of SRB, and avoiding the sudden large supply of sulfate resulting in the explosive generation of hydrogen sulfide by SRB. In Comparative Example 1, montmorillonite was not modified with quaternary ammonium salt and lacked a hydrophobic barrier, so the sodium sulfate was released relatively quickly; in Comparative Example 2, it was first modified with quaternary ammonium salt and then loaded with sodium sulfate, and the long chains of the quaternary ammonium salt did not play a role in hindering the diffusion of SO 4 2- and Na + , resulting in a relatively fast release rate. Moreover, it is difficult for sodium sulfate to enter the montmorillonite layers, which will also reduce the loading amount; in Comparative Example 3, sodium sulfate was directly added without a slow-release effect, and SRB metabolized violently due to the sudden increase in the substrate, and a large amount of hydrogen sulfide gas was not captured and precipitated by heavy metal ions in time, resulting in a soaring concentration. The slow-release structure of the modified montmorillonite limits ion diffusion at the molecular level and is the key to inhibiting hydrogen sulfide release.

[0046] As can be seen from the experimental data in Table 1, Example 2 shows better performance in pH adjustment ability compared to Comparative Examples 6-9. This may be because the main components of the steel slag powder in Example 2 are alkaline substances such as CaO and FeO. After purification with dilute hydrochloric acid, it can neutralize acidic wastewater and form a neutral environment suitable for SRB metabolism. In Comparative Examples 6-7, the amount of steel slag powder is insufficient, resulting in incomplete acid neutralization and inhibited SRB activity; in Comparative Examples 8-9, the amount of steel slag powder is excessive, leading to too high pH, which destroys the SRB enzyme system and the flocculation structure of lignosulfonate. The reasonable dosage of steel slag powder provides the best conditions for physical adsorption, biodegradation, and flocculation reactions by adjusting pH, avoiding the negative impact of extreme pH on the treatment effect.

[0047] As can be seen from the experimental data in Table 1, Example 2 is significantly superior to each comparative example in terms of heavy metal removal rate. This is due to its multi-component synergistic effect and precise formulation design, while the removal efficiency of each comparative example decreases due to the lack of key components, incorrect modification process, or dosage imbalance. In Comparative Examples 1-3, the slow-release mechanism of montmorillonite fails or the modification is improper, resulting in out-of-control release of sodium sulfate: in Comparative Example 1, montmorillonite is not modified with quaternary ammonium salt, lacking a hydrophobic barrier, and the rapid release of sodium sulfate disrupts SRB metabolism, and some S²⁻ volatilizes in the form of H 2 S, reducing the effective sulfur ions; in Comparative Example 2, the modification order is reversed, making it difficult for sodium sulfate to be embedded between layers and losing the slow-release effect; in Comparative Example 3, sodium sulfate is directly added, and SRB generates H 2 S explosively due to the sudden increase in the substrate, and the sulfur ions do not fully participate in the precipitation reaction. The heavy metal removal rates of all three are lower than that of Example 2; in Comparative Examples 4-5, the removal rate decreases due to the lack of composite synergy: fly ash is porous but has a single adsorption site, and although the zeolite molecular sieve effect is strong, it lacks alkaline buffering. After the two are combined and activated by alkaline treatment, the active sites of aluminosilicate are formed, resulting in a synergy of "ion exchange + molecular sieve adsorption + hydroxide precipitation", making up for the adaptability defects of single materials to complexed heavy metals and acidic environments; in Comparative Examples 6-9, the removal effect is affected by pH adjustment imbalance: insufficient steel slag powder leads to incomplete acid neutralization, inhibited SRB activity and insufficient flocculation ions; excessive amounts cause strong alkalinity, destroying the zeolite structure and forming soluble heavy metal hydroxy complexes, resulting in a decrease in the removal rate, all lower than the neutral environment of Example 2; in Comparative Example 10, due to the lack of a biological precipitation mechanism and relying only on physical adsorption, the ability to remove heavy metals becomes weaker, while in Example 2, S²⁻ is generated through SRB metabolism, forming extremely low solubility product sulfides, greatly improving the removal rate of heavy metal ions.

[0048] As can be seen from the experimental data in Table 1, in terms of COD removal rate, Example 2 is significantly superior to Comparative Examples 1-10. Its advantage stems from the ternary synergistic mechanism of "biodegradation + adsorption + flocculation". The efficiency differences in each comparative example are caused by the lack or imbalance of key links: In Comparative Examples 1-2, in the former, the quaternary ammonium salt modification was not carried out, and sodium sulfate was released relatively fast, resulting in fluctuations in the metabolic efficiency of SRB. In the latter, the modification sequence was reversed, and the interlayer structure of montmorillonite was damaged, affecting the hydrophobic adsorption of organic matter, resulting in a removal rate lower than that of Example 2; In Comparative Example 3, because sodium sulfate was not loaded on montmorillonite, it dissolved rapidly, leading to excessive consumption of organic matter by SRB in a short period, and the accumulation of metabolic intermediates. Moreover, the unmodified montmorillonite had few adsorption sites and insufficient capture of refractory organic matter; In Comparative Examples 4-5, due to the lack of synergistic adsorption of the complex, fly ash was porous but had weak adsorption capacity for macromolecular organic matter, and the zeolite molecular sieve effect was difficult to cover complex organic matter. After the complex in Example 2 was treated with alkali, the specific surface area increased, and the adsorption capacity for organic pollutants was improved; In Comparative Examples 6-9, insufficient steel slag powder led to the inhibition of SRB activity in an acidic environment, and the flocculation of lignosulfonate was less efficient due to the lack of Ca² + 、Fe³ + And the efficiency decreased; Excessive amounts caused strong alkalinity, destroying the molecular structure of lignin and reducing the bridging effect on colloidal organic matter; In Comparative Example 10, due to complete reliance on physicochemical treatment and the lack of biodegradation of organic matter by SRB, the removal ability for soluble organic matter (such as glucose and phenols) was extremely weak.

[0049] As can be seen from the experimental data in Table 1, in terms of turbidity removal rate, Example 2 performed better than Comparative Examples 1-10. This may be because an appropriate amount of steel slag powder was added in Example 2, releasing sufficient Ca² + 、Fe³ + , forming a high-strength flocculant with lignosulfonate, neutralizing the particle charge and promoting bridging; The fly ash-zeolite complex and modified montmorillonite served as "floc skeletons", adsorbing colloidal particles through their porous structures; The extracellular polymeric substances (EPS) produced by SRB metabolism acted as biological adhesives, enhancing the strength of the flocs. The three worked together to quickly aggregate suspended solids into large particles and settle. The efficiency differences in each comparative example were caused by the failure of key links: In Comparative Examples 1-2, due to incomplete modification of montmorillonite and incorrect loading order, there were few adsorption sites and it could not effectively serve as the core of the flocs. In Comparative Example 3, the sudden release of sodium sulfate led to an explosive metabolism of SRB, and the generated H 2 S gas hindered the aggregation of flocs, and the interlayer structure of the unmodified montmorillonite was dense, making it difficult to adsorb colloidal particles; In Comparative Examples 4-5, because the specific surface area of a single material was small and its function was single, fly ash was porous but had uneven pore sizes, and the zeolite molecular sieve had weak capture ability for colloidal particles. After the complex in Example 2 was treated with alkali, the surface roughness increased, providing more attachment sites for the flocs; In Comparative Examples 6-9, due to insufficient alkaline components, Ca² + 、Fe³+ With a small release amount, the lignosulfonate cannot effectively neutralize the particle charge, and the floc particle size is small; in Comparative Examples 8-9, the strong alkalinity destroys the molecular chain structure of lignin and reduces its bridging ability with the suspended matter; in Comparative Example 10, due to the lack of extracellular polymers (EPS) produced by SRB metabolism, the flocs lack sticky bridging substances, and it is difficult for fine particles to aggregate into large flocs, resulting in a significant decrease in the sedimentation rate.

[0050] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A wastewater treatment composition, characterized in that The method comprises the following raw materials in parts by weight: 30-40 parts of steel slag powder, 20-30 parts of fly ash-zeolite composite, 10-15 parts of modified montmorillonite, 5-10 parts of lignin sulfonate, and 1-5 parts of SRB sulfate-reducing bacteria; The preparation process of the fly ash-zeolite complex is as follows: fly ash and natural clinoptilolite are added to an alkaline solution, heated to 75-85° C. under stirring, reacted for 1-3 hours, cooled to room temperature, centrifuged, the solid was washed with deionized water until the pH was neutral, dried and ground, and passed through a 150-250 mesh sieve to obtain the fly ash-zeolite complex; The preparation process of the modified montmorillonite is as follows: sodium montmorillonite is added to dilute hydrochloric acid, ultrasonicated for 30-50 minutes, filtered, washed with deionized water until neutral, dried and ground, passed through a 100-200 mesh sieve, and then added to a sodium sulfate solution, heated to 50-60° C. and ultrasonicated for 20-40 minutes, then stirred and reacted for 1-3 hours, filtered, washed, dried, ground, and passed through a 100-200 mesh sieve, and finally added to a hexadecyltrimethylammonium bromide solution, stirred and reacted at room temperature for 40-60 minutes, filtered, washed, dried, and passed through a 100-200 mesh sieve to obtain the modified montmorillonite.

2. The wastewater treatment composition according to claim 1, characterized in that The particle size of the steel slag powder is 80-120 meshes.

3. The wastewater treatment composition according to claim 1, characterized in that The lignin sulfonate refers to sodium lignin sulfonate or potassium lignin sulfonate.

4. The wastewater treatment composition according to claim 1, characterized in that In the preparation process of the fly ash-zeolite composite, the weight ratio of fly ash, natural clinoptilolite and alkaline solution is 1:1:3-7, and the alkaline solution refers to a sodium hydroxide aqueous solution with a concentration of 5 mol / L.

5. The wastewater treatment composition according to claim 1, characterized in that In the preparation process of the modified montmorillonite, the weight ratio of sodium montmorillonite, dilute hydrochloric acid, sodium sulfate solution and hexadecyltrimethylammonium bromide solution is 1:8-12:10-20:10-20, dilute hydrochloric acid refers to a hydrochloric acid solution with a concentration of 10%, sodium sulfate solution refers to a sodium sulfate solution with a concentration of 5%, and hexadecyltrimethylammonium bromide solution refers to a hexadecyltrimethylammonium bromide solution with a concentration of 10%.

6. The method for preparing the wastewater treatment composition according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Add the steel slag powder to dilute hydrochloric acid, stir at room temperature for 30-50 min, filter, wash with deionized water until the pH is neutral, and dry to obtain the purified steel slag powder; S2. The purified steel slag powder, fly ash-zeolite complex, modified montmorillonite, lignin sulfonate and SRB sulfate-reducing bacteria are mixed, added into a ball mill, mixed for 10-20 minutes, and passed through a 100-200 mesh sieve to obtain a wastewater treatment composition.

7. The method for preparing the wastewater treatment composition according to claim 6, characterized in that: The weight ratio of the steel slag powder to the dilute hydrochloric acid in S1 is 1:5-10.

8. The method for preparing the wastewater treatment composition according to claim 6, characterized in that: The dilute hydrochloric acid in S1 refers to a hydrochloric acid solution with a concentration of 10%.

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