A wastewater treatment composition and its preparation method

Abstract

The present invention relates to the technical field of wastewater treatment, and specifically relates to a wastewater treatment composition and a preparation method thereof. The wastewater treatment composition is composed of the following raw materials: steel slag powder, fly ash-zeolite composite, modified montmorillonite, lignosulfonate, SRB sulfate-reducing bacteria; wherein the fly ash-zeolite composite is made by hydrothermal reaction of a certain proportion of fly ash and natural clinoptilolite, and the modified montmorillonite is first loaded with sodium sulfate and then modified with quaternary ammonium salt. The wastewater treatment composition prepared by the present invention realizes deep removal of heavy metal ions, efficient treatment of organic matter and suspended solids, control of hydrogen sulfide gas release, and pH adjustment of acidic wastewater through multi-mechanism synergy among various components, and has the advantages of environmental friendliness, low cost and strong universality.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular 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, threatening the ecological environment and human health. At present, the wastewater treatment technologies mainly include chemical precipitation method, adsorption method, biological treatment method, etc., but there are still many problems to be solved urgently:

[0003] 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; a single adsorption material (such as fly ash, zeolite) has a single adsorption site and poor selectivity, and has a low removal efficiency for complexed heavy metals, especially the adsorption capacity decreases significantly in an acidic environment.

[0004] 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 malodorous 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.

[0005] 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

[0006] 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.

[0007] Based on the above purpose, the present invention provides a wastewater treatment composition, which includes 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;

[0008] The preparation process of the fly ash-zeolite composite is as follows: Add fly ash and natural clinoptilolite into an alkaline solution, heat it to 75-85 °C with stirring, react for 1-3 h, cool it to room temperature, then centrifuge. Wash the solid with deionized water until the pH is neutral, dry it, grind it, and sieve it through a 150-250 mesh sieve to obtain the fly ash-zeolite composite;

[0009] The preparation process of the modified montmorillonite is as follows: Add sodium-based montmorillonite into dilute hydrochloric acid, ultrasonicate for 30-50 min, filter, wash it with deionized water until neutral, dry it, grind it, and sieve it through a 100-200 mesh sieve. Then add it into a sodium sulfate solution, heat it to 50-60 °C and ultrasonicate for 20-40 min, and then react for 1-3 h with stirring. Filter, wash, dry, grind it, and sieve it through a 100-200 mesh sieve. Finally, add it into a cetyltrimethylammonium bromide solution, stir and react at room temperature for 40-60 min, filter, wash, dry it, and sieve it through a 100-200 mesh sieve to obtain the modified montmorillonite.

[0010] Preferably, the particle size of the steel slag powder is 80-120 mesh.

[0011] Preferably, the lignosulfonate refers to sodium lignosulfonate or potassium lignosulfonate.

[0012] 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.

[0013] 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.

[0014] Preferably, the dilute hydrochloric acid in the preparation process of the modified montmorillonite refers to a hydrochloric acid solution with a concentration of 10%.

[0015] Preferably, the sodium sulfate solution in the preparation process of the modified montmorillonite refers to a sodium sulfate solution with a concentration of 5%.

[0016] Preferably, the cetyltrimethylammonium bromide solution in the preparation process of the modified montmorillonite refers to a cetyltrimethylammonium bromide solution with a concentration of 10%.

[0017] Preferably, the purpose of the modified montmorillonite is to achieve a slow-release effect for 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 being released from the montmorillonite layers into the external solution slow, thus achieving the slow-release effect. At the same time, between the montmorillonite layers, the diffusion of SO4 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 the ions. The ions need to slowly diffuse through the gaps in the hydrophobic long chains to be released from the montmorillonite layers, further prolonging the release time.

[0018] Furthermore, the present invention also provides a preparation method for the above wastewater treatment composition, which specifically includes the following steps:

[0019] 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 dry to obtain purified steel slag powder;

[0020] 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 pass through a 100 - 200 mesh sieve to obtain a wastewater treatment composition.

[0021] Preferably, in S1, the weight ratio of the steel slag powder to the dilute hydrochloric acid is 1:5 - 10.

[0022] Preferably, the dilute hydrochloric acid in S1 refers to a hydrochloric acid solution with a concentration of 10%.

[0023] Preferably, the action mechanism of the SRB sulfate-reducing bacteria is as follows:

[0024] Organic matter + SO4 2- + SRB → S 2- + CO2↑ + H2O

[0025] 2M n+ + nS 2- → M2S n ↓, where M n+ represents heavy metal ions.

[0026] The beneficial effects of the present invention:

[0027] 1. The present invention realizes the efficient removal of heavy metal ions through the synergistic action of the triple mechanisms of "bioreduction - composite adsorption - chemical precipitation". Modified montmorillonite is loaded with sodium sulfate and modified with cetyltrimethylammonium bromide to form an interlayer hydrophobic barrier structure, which controllably releases sulfate for the metabolism of SRB 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, so that there is sufficient reaction precipitation time with heavy metals, avoiding the defects of H2S volatilization and low heavy metal sedimentation efficiency in the existing anaerobic ponds using reducing bacteria; after the fly ash - zeolite complex is co - treated with alkali, the active sites of aluminosilicate are activated, combining the molecular sieve effect of zeolite and the porous adsorption capacity of fly ash to form an adsorbent. In high - concentration metal - ion wastewater, the saturated adsorption of the adsorbent is utilized (because the concentration is high, the adsorbent is easily saturated with adsorption). After adsorption saturation, with the metabolism of reducing bacteria, due to the concentration difference, the adsorbent continuously releases new heavy metal ions, and precipitation occurs near the microbial community or the adsorbent. The process is an equilibrium reaction of adsorption - desorption equilibrium of the adsorbent 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 risk of sludge generation and secondary pollution.

[0028] 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, decomposing macromolecular organic matter into and , reducing from the source; the fly ash - zeolite complex 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 through charge neutralization and bridging effects for rapid sedimentation. 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.

[0029] 3. Through material modification and process optimization, the present invention effectively solves the problems of hydrogen sulfide gas release and chemical agent residues in traditional SRB processes. Traditional montmorillonite generally uses its adsorption function in wastewater treatment, while the modified montmorillonite prepared in the present invention utilizes the sulfate it loads to achieve a slow - release characteristic, so that The release rate matches the metabolic rhythm of SRB to avoid the explosive generation caused by the sudden increase of substrates. Meanwhile, the sulfide precipitation reaction consumes synchronously to reduce 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. There is no introduction of secondary pollutants in the overall process, 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

[0030] 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 with reference to specific embodiments.

[0031] The sources of the reagent raw materials used in the embodiments of the present invention are as follows:

[0032] The steel slag powder is purchased from Lingshou Baiyi Mineral Products Processing Factory, with a particle size of 80-120 mesh; the fly ash is purchased from Lingshou Zhanteng Mineral Products Processing Factory, 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 Technology Co., Ltd., with 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 Technology Co., Ltd., with a purity of 99%; the sodium sulfate is purchased from Shanghai Macklin Biochemical Technology Co., Ltd., with a purity of 99%.

[0033] Example 1: A wastewater treatment composition and its preparation method include the following process:

[0034] (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;

[0035] (2) Add 3 Kg of sodium-based montmorillonite to 24 Kg of 10% dilute hydrochloric acid, ultrasonicate 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, ultrasonicate for 20 min, and then react under 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;

[0036] (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;

[0037] (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.

[0038] Example 2: A wastewater treatment composition and its preparation method, including the following process:

[0039] (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;

[0040] (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 5% sodium sulfate solution, heat 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 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;

[0041] (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;

[0042] (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.

[0043] Example 3: A wastewater treatment composition and its preparation method, including the following process:

[0044] (1) Add 4 Kg of fly ash and 4 Kg of natural clinoptilolite to 28 Kg of 5 mol / L sodium hydroxide solution, heat to 85 °C with stirring, react for 3 h, cool to room temperature, centrifuge, wash the solid with deionized water until the pH is neutral, dry and grind, and pass through a 250-mesh sieve to obtain a fly ash-zeolite composite;

[0045] (2) Add 4 Kg of sodium-based montmorillonite to 48 Kg of 10% dilute hydrochloric acid, ultrasonicate for 50 min, filter, wash with deionized water until neutral, dry and grind, pass through a 200-mesh sieve, then add to 80 Kg of 5% sodium sulfate solution, heat 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 to 80 Kg of 10% cetyltrimethylammonium bromide solution, stir and react at room temperature for 60 min, filter, wash, and dry, and pass through a 200-mesh sieve to obtain modified montmorillonite;

[0046] (3) Add 9 Kg of steel slag powder to 90 Kg of 10% dilute hydrochloric acid, stir at room temperature for 50 min, filter, wash with deionized water until the pH is neutral, and dry to obtain purified steel slag powder;

[0047] (4) Mix 8 Kg of purified steel slag powder, 6 Kg of fly ash-zeolite composite, 3 Kg of modified montmorillonite, 2 Kg of sodium lignosulfonate, and 1 Kg of SRB sulfate-reducing bacteria, add them to a ball mill, mix for 20 min, and pass through a 200-mesh sieve to obtain a wastewater treatment composition.

[0048] Example 4: A wastewater treatment composition and its preparation method, including the following process:

[0049] (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 and grind, and pass through a 200-mesh sieve to obtain a fly ash-zeolite composite;

[0050] (2) Add 3 Kg of sodium 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 5% sodium sulfate solution, 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 10% cetyltrimethylammonium bromide solution, stir and react at room temperature for 50 min, filter, wash, and dry, and then pass through a 150-mesh sieve to obtain modified montmorillonite;

[0051] (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;

[0052] (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 potassium 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.

[0053] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that sodium montmorillonite is 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 process:

[0054] (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 up 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;

[0055] (2) Add 3 Kg of sodium 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 5% sodium sulfate solution, 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 to obtain modified montmorillonite;

[0056] (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;

[0057] (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.

[0058] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that sodium - based montmorillonite is first added to cetyltrimethylammonium bromide solution and then to sodium sulfate solution. The specific preparation process is as follows: A wastewater treatment composition and its preparation method include the following process:

[0059] (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 and then grind, and pass through a 200 - mesh sieve to obtain a fly ash - zeolite composite;

[0060] (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 and grind through a 150 - mesh sieve, then add to 45 Kg of 10% cetyltrimethylammonium bromide solution, stir and react at room temperature for 50 min, filter, wash, dry, grind and then pass through a 150 - mesh sieve. Finally, add 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;

[0061] (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;

[0062] (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.

[0063] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that sodium sulfate is not loaded onto 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:

[0064] (1) Add 3 Kg of fly ash and 3 Kg of natural clinoptilolite into 15 Kg of 5 mol / L sodium hydroxide solution. While stirring, heat up to 80 °C and react for 2 h. After cooling to room temperature, centrifuge. Wash the solid with deionized water until the pH is neutral. After drying, grind it and pass through a 200-mesh sieve to obtain the fly ash-zeolite composite;

[0065] (2) Add 8 Kg of steel slag powder into 60 Kg of 10% dilute hydrochloric acid. Stir at room temperature for 40 min, filter, and wash with deionized water until the pH is neutral. After drying, obtain the purified steel slag powder;

[0066] (3) Mix 7 Kg of the purified steel slag powder, 5 Kg of the 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 into a ball mill and mix for 15 min. After passing through a 150-mesh sieve, obtain a wastewater treatment composition.

[0067] 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:

[0068] (1) Add 3 Kg of sodium-based montmorillonite into 30 Kg of 10% dilute hydrochloric acid. Ultrasonic for 40 min, filter, wash with deionized water until neutral, then 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, ultrasonic 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 into 45 Kg of 10% cetyltrimethylammonium bromide solution and stir at room temperature for 50 min. Filter, wash, and dry, and then pass through a 150-mesh sieve to obtain the modified montmorillonite;

[0069] (2) Add 8 Kg of steel slag powder into 60 Kg of 10% dilute hydrochloric acid. Stir at room temperature for 40 min, filter, and wash with deionized water until the pH is neutral. After drying, obtain the purified steel slag powder;

[0070] (3) Mix 7 Kg of the purified steel slag powder, 5 Kg of fly ash, 2.5 Kg of the modified montmorillonite, 1.5 Kg of sodium lignosulfonate, and 500 g of SRB sulfate-reducing bacteria. Add them into a ball mill and mix for 15 min. After passing through a 150-mesh sieve, obtain a wastewater treatment composition.

[0071] Comparative Example 5: The difference between Comparative Example 5 and Example 2 is that the fly ash-zeolite composite is replaced with natural clinoptilolite. The specific preparation process is as follows: A wastewater treatment composition and its preparation method include the following process:

[0072] (1) Grind 6 Kg of natural clinoptilolite, and pass it through a 200-mesh sieve to obtain zeolite powder;

[0073] (2) Add 3 Kg of sodium-based montmorillonite to 30 Kg of dilute hydrochloric acid with a concentration of 10%, 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 sodium sulfate solution with a concentration of 5%, heat up to 55 °C, sonicate 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, and dry, and then pass through a 150-mesh sieve to obtain modified montmorillonite;

[0074] (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;

[0075] (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.

[0076] Comparative Example 6: The difference between Comparative Example 6 and Example 2 is that the addition amount of purified steel slag powder is adjusted to 3 Kg.

[0077] Comparative Example 7: The difference between Comparative Example 7 and Example 2 is that the addition amount of purified steel slag powder is adjusted to 5 Kg.

[0078] Comparative Example 8: The difference between Comparative Example 8 and Example 2 is that the addition amount of purified steel slag powder is adjusted to 9 Kg.

[0079] Comparative Example 9: The difference between Comparative Example 9 and Example 2 is that the addition amount of purified steel slag powder is adjusted to 11 Kg.

[0080] Comparative Example 10: The difference between Comparative Example 10 and Example 2 is that no SRB sulfate-reducing bacteria are added.

[0081] Performance test:

[0082] Prepare 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.

[0083] 1. Testing the concentration of hydrogen sulfide gas during the wastewater treatment process: 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. Record the maximum hydrogen sulfide concentration. The experimental results are shown in Table 1.

[0084] 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. After stirring for 30 min, measure the pH of the wastewater. The experimental results are shown in Table 1.

[0085] 3. Heavy metal ion removal rate: 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.

[0086] 4. COD and turbidity removal effect tests: In the experiment for measuring the heavy metal removal rate, simultaneously measure the COD removal rate W = and the turbidity removal rate Y = of the wastewater after treatment of the samples in Examples 1-4 and Comparative Examples 1-10. The experimental results are shown in Table 1.

[0087] Table 1 Performance Tests

[0088]

[0089] Data analysis:

[0090] It can be seen from the experimental data in Table 1 that the wastewater treatment compositions prepared in Examples 1-4 using the present invention have significant advantages. They perform excellently in terms of heavy metal removal rate, can efficiently remove heavy metal ions in wastewater. From the COD removal rate and turbidity removal rate, it can be seen that this kind of wastewater treatment composition has a strong ability to remove organic matter and suspended solids, and the concentration of hydrogen sulfide gas generated during the wastewater treatment process is extremely low, being 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 at the leading level among the examples, showing the best wastewater treatment effect.

[0091] It can be seen from the experimental data in Table 1 that Example 2 has significant advantages over Comparative Examples 1-3 in terms of the maximum hydrogen sulfide concentration. This may be because the modified montmorillonite in Example 2 is first loaded with sodium sulfate and then modified with 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 hindrance of the hydrophobic long chains to contact the sodium sulfate between the layers, enabling SO4 2- and Na + to slowly diffuse into the solution, matching the metabolic rate of SRB and avoiding a sudden large supply of sulfate that would cause an explosive generation of hydrogen sulfide by SRB. In Comparative Example 1, montmorillonite was not modified with quaternary ammonium salt, lacking a hydrophobic barrier, resulting in a faster release of sodium sulfate. In Comparative Example 2, montmorillonite was first modified with quaternary ammonium salt and then loaded with sodium sulfate. The long chains of the quaternary ammonium salt did not play a role in hindering the diffusion of SO4 2- and Na + , leading to a faster release rate. Moreover, it was difficult for sodium sulfate to enter the interlayers of montmorillonite, which also reduced the loading amount. In Comparative Example 3, sodium sulfate was directly added without a slow-release effect. SRB metabolized violently due to a sudden increase in the substrate, and a large amount of hydrogen sulfide gas was not promptly captured and precipitated by heavy metal ions, 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.

[0092] It can be seen from the experimental data in Table 1 that Example 2 performs better than Comparative Examples 6-9 in terms of pH adjustment ability. 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 the metabolism of SRB. In Comparative Examples 6-7, the amount of steel slag powder was insufficient, and the acid neutralization was incomplete, inhibiting the activity of SRB. In Comparative Examples 8-9, the amount of steel slag powder was excessive, resulting in too high a pH, which damaged the enzyme system of SRB 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 the pH, avoiding the negative impact of extreme pH on the treatment effect.

[0093] 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 absence of key components, incorrect modification processes, or dosage imbalances. 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, quaternary ammonium salt is not used for modification, and montmorillonite lacks a hydrophobic barrier, causing rapid release of sodium sulfate, metabolic disorder of SRB, and partial volatilization of S²⁻ in the form of H2S, reducing the effective sulfur ions; in Comparative Example 2, the modification sequence 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 H2S explosively due to a sudden increase in the substrate, and 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", which makes up for the adaptability defects of single materials to complex heavy metals and acidic environments; in Comparative Examples 6-9, the pH adjustment imbalance affects the removal effect: Insufficient steel slag powder leads to incomplete acid neutralization, inhibition of SRB activity, and insufficient flocculation ions; excessive amounts cause strong alkalinity, damaging 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 weak, while in Example 2, S²⁻ is generated through SRB metabolism, forming sulfides with extremely low solubility products, greatly improving the removal rate of heavy metal ions.

[0094] 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", while the efficiency differences in each comparative example are caused by the absence or imbalance of key links: In Comparative Examples 1-2, in the former, quaternary ammonium salt is not used for modification, resulting in relatively fast release of sodium sulfate and fluctuating SRB metabolic efficiency; in the latter, the modification sequence is reversed, damaging the interlayer structure of montmorillonite and affecting the hydrophobic adsorption of organic matter, resulting in a lower removal rate than that of Example 2; in Comparative Example 3, since sodium sulfate is not loaded on montmorillonite, rapid dissolution leads to excessive consumption of organic matter by SRB in a short period, accumulation of metabolic intermediates, and few adsorption sites on unmodified montmorillonite, insufficient capture of refractory organic matter; in Comparative Examples 4-5, due to the lack of synergistic adsorption of the composite, fly ash is porous but has weak adsorption ability for macromolecular organic matter, and the zeolite molecular sieve effect is difficult to cover complex organic matter, while the specific surface area of the composite in Example 2 increases after alkaline treatment, enhancing the adsorption ability for organic pollutants; in Comparative Examples 6-9, insufficient steel slag powder leads to inhibition of SRB activity in an acidic environment, and lignosulfonate flocculation lacks Ca² + 、Fe³ +The efficiency decreases; an excessive amount causes strong alkalinity, destroys the molecular structure of lignin, and reduces 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 ability to remove soluble organic matter (such as glucose and phenols) is extremely weak.

[0095] It can be seen from the experimental data in Table 1 that in terms of turbidity removal rate, Example 2 performs better than Comparative Examples 1-10. This may be because an appropriate amount of steel slag powder is added in Example 2 to release sufficient Ca² + 、Fe³ + , which forms a high-strength flocculant with lignosulfonate, neutralizes the particle charge and promotes bridging; the fly ash-zeolite composite and modified montmorillonite act as "floc skeletons", adsorbing colloidal particles through their porous structures; the extracellular polymeric substances (EPS) produced by SRB metabolism act as biological adhesives to enhance the strength of the flocs. The three work together to quickly aggregate the suspended solids into large particles and settle. The efficiency differences in each comparative example are caused by the failure of key links: in Comparative Examples 1-2, due to incomplete modification of montmorillonite and incorrect loading order, there are few adsorption sites and it cannot effectively serve as the core of the flocs. In Comparative Example 3, the sudden release of sodium sulfate leads to an explosive metabolism of SRB, and the generated H2S gas hinders the aggregation of the flocs. Moreover, the interlayer structure of unmodified montmorillonite is dense and it is difficult to adsorb colloidal particles; in Comparative Examples 4-5, because the specific surface area of a single material is small and the function is single, the pores of fly ash are porous but the pore sizes are uneven, and the zeolite molecular sieve has a weak ability to capture colloidal particles. After the composite body in Example 2 is treated with alkali, the surface roughness increases, providing more attachment sites for the flocs; in Comparative Examples 6-9, due to insufficient alkaline components, the release amounts of Ca² + 、Fe³ + are small, and 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 solids; in Comparative Example 10, due to the lack of extracellular polymeric substances (EPS) produced by SRB metabolism, the flocs lack sticky bridging substances, and it is difficult for fine particles to aggregate into large flocs, and the sedimentation speed decreases significantly.

[0096] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is only 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, It includes 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 complex is as follows: Add fly ash and natural clinoptilolite into an alkaline solution, heat it to 75 - 85 °C with stirring, react for 1 - 3 h, after cooling to room temperature, centrifuge, wash the solid with deionized water until the pH is neutral, dry and then grind it, and obtain the fly ash - zeolite complex after passing through a 150 - 250 - mesh sieve; The preparation process of the modified montmorillonite is as follows: Add sodium - based montmorillonite into dilute hydrochloric acid, ultrasonicate for 30 - 50 min, filter, wash it with deionized water until neutral, dry and grind it, then pass through a 100 - 200 - mesh sieve, add it into a sodium sulfate solution, heat it to 50 - 60 °C and ultrasonicate for 20 - 40 min, then react for 1 - 3 h with stirring, filter, wash, dry and grind it, and finally pass through a 100 - 200 - mesh sieve. Finally, add it into a cetyltrimethylammonium bromide solution, stir and react at room temperature for 40 - 60 min, filter, wash, dry and then pass through a 100 - 200 - mesh sieve to obtain the modified montmorillonite.

2. The wastewater treatment composition according to claim 1, wherein The particle size of the steel slag powder is 80 - 120 mesh.

3. The wastewater treatment composition according to claim 1, wherein The lignosulfonate refers to sodium lignosulfonate or potassium lignosulfonate.

4. The wastewater treatment composition according to claim 1, wherein In the preparation process of the fly ash - zeolite complex, 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 - based montmorillonite, dilute hydrochloric acid, sodium sulfate solution and cetyltrimethylammonium bromide solution is 1:8 - 12:10 - 20:10 - 20. The dilute hydrochloric acid refers to a hydrochloric acid solution with a concentration of 10%, the sodium sulfate solution refers to a sodium sulfate solution with a concentration of 5%, and the cetyltrimethylammonium bromide solution refers to a cetyltrimethylammonium bromide solution with a concentration of 10%.

6. A method for preparing the wastewater treatment composition according to any one of claims 1 to 5, characterized in that, It includes the following steps: S1. Add the steel slag powder into dilute hydrochloric acid, stir at room temperature for 30 - 50 min, filter, wash it with deionized water until the pH is neutral, and obtain the 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 into a ball mill, mix for 10 - 20 min, and obtain a wastewater treatment composition after passing through a 100 - 200 - mesh sieve.

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

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

Images