Composition for controlling phosphorus release and phosphate solubilizing bacteria enrichment of coastal river and lake bottom mud, preparation method and application thereof

Abstract

The invention discloses a composition for controlling phosphorus release and phosphate solubilizing bacteria enrichment of coastal river and lake bottom mud, and a preparation method and application thereof. The composition contains calcium oxide, magnesium chloride, ferric trichloride and aluminum sulfate. Also disclosed are pharmaceutical agents containing the compositions. The composition and the medicament have the effects of controlling phosphorus release and phosphate solubilizing bacteria enrichment of the coastal river and lake bottom mud.

Description

Technical Field

[0001] The present invention relates to the field of phosphorus pollution, and in particular to a composition for controlling phosphorus release and enrichment of phosphate-solubilizing bacteria in coastal river and lake bottom mud, a preparation method and use thereof. Background Art

[0002] Phosphorus pollution is a crucial control target in protecting the water quality of rivers and lakes. Especially in recent years, with the continuous strengthening of exogenous pollution control measures, endogenous pollution has gradually become the main factor restricting water quality improvement. Endogenous phosphorus pollution mainly comes from the re-release of phosphorus accumulated in the bottom sediment. In order to effectively control endogenous pollution, there are usually two technical approaches: one is to excavate the bottom sediment ex situ through dredging, thereby removing the main source of phosphorus in the bottom sediment; the other is to adopt in situ treatment technology, in which phosphorus control agents are added to inhibit the release of phosphorus in the bottom sediment. This is a more widely used method for rivers and lakes that are difficult to dredge. Phosphorus control agents can quickly lock phosphorus in the bottom sediment through chemical reactions or physical effects, thereby reducing its migration and release to the overlying water.

[0003] Currently, phosphate control agents can be primarily categorized into two types based on their composition: lanthanide-based agents and calcium-based agents. Lanthanide-based agents, due to their high chemical affinity and stability for phosphate, are highly effective phosphate-binding agents. However, their high cost severely limits their widespread application. In contrast, calcium-based agents have attracted widespread attention due to their low cost and ability, under specific conditions, to form stable calcium phosphate compounds with phosphate in sediments. However, the high pH generated during the application of calcium-based agents has become a significant constraint, as national surface water standards clearly stipulate that the pH level in water bodies should be maintained between 6 and 9. Therefore, to overcome the limitations of single calcium-based agents, composite agents, leveraging the synergistic effects of multiple components, have the potential to effectively bind phosphate while maintaining pH within an ecologically safe range. Furthermore, erosion by water in sediment environments can lead to agent loss and a decrease in binding capacity. By rationally combining calcium, magnesium, iron, and aluminum agents, the physical strength of the agent can be enhanced, thereby improving its stability in water bodies. However, the combination method for these four agents is still in the exploratory stage. How to achieve a balance between pH regulation and agent stability while maintaining efficient phosphorus locking effect is still a technical problem that needs to be solved urgently.

[0004] The research on traditional phosphorus control agents is mostly centered on chemical phosphorus locking, and the main focus is on reducing the release of phosphorus by generating insoluble compounds through the reaction of agents with phosphate groups. However, these studies generally ignore the profound impact of microorganisms on the phosphorus cycle, especially the presence of phosphate-solubilizing bacteria, which may have an important negative effect on the effect of phosphorus control agents. Phosphate-solubilizing bacteria are a type of microorganism that can convert insoluble phosphorus compounds into soluble phosphate groups. Their activity may cause the fixed phosphorus in the sediment to be released again, thereby weakening the durability and overall effect of phosphorus control agents. Therefore, in the research and development and application of phosphorus control agents, how to effectively inhibit the activity of phosphate-solubilizing bacteria and reduce their interference with the phosphorus control effect has become an issue that needs to be considered. However, in the existing invention patents and related technical research, there has not been a systematic discussion on the problem of phosphate control agents enriching phosphate-solubilizing bacteria, and there is an obvious research gap in this field.

[0005] Compared with inland water bodies, coastal river and lake environments have their own unique salinity interference problem. Salinity has a significant impact on the application effect of phosphorus control agents. On the one hand, the types and concentrations of dissolved ions in high-salt environments may compete with the active components in the agent, weakening the agent's phosphorus lock efficiency; on the other hand, salinity may also change the interaction between the agent and the surface of the sediment particles, resulting in increased loss of the agent. In addition, salinity may also have a complex impact on the actual application effect of phosphorus control agents by changing the structure of the sediment microbial community and the activity of phosphate-solubilizing bacteria. Therefore, in order to adapt to the special environment of coastal rivers and lakes, it is crucial to develop phosphorus control agents that can maintain efficient phosphorus lock performance under high-salt conditions. Summary of the Invention

[0006] In order to meet the above-mentioned challenges, the present invention proposes a method for controlling the release of phosphorus from the bottom mud of coastal rivers and lakes and the enrichment of phosphate-solubilizing bacteria. The core strategy of this method is to develop a comprehensive mixed agent based on four ingredients: calcium oxide (A), magnesium chloride (B), ferric chloride (C), and aluminum sulfate (D). Through a reasonable component ratio, the agent can achieve efficient fixation of bottom mud phosphorus while keeping the water pH within the ecological safety range, solving the problem that calcium-based single agents are prone to causing excessive pH in environmental water bodies, and promoting the synergistic solidification reaction of calcium oxide and other ingredients in the agent after contacting water to form a gel, effectively enhancing the physical connection between the agent particles, thereby improving the anti-scouring ability. At the same time, the inhibition of phosphate-solubilizing bacteria is carried out by controlling the pH of the agent within an appropriate range.

[0007] Furthermore, based on the above steps, the present invention further introduces silicon dioxide as a modifying material, and by coating and modifying the surface of the agent particles, improves the stability and sustainability of the agent under high-salt conditions. While achieving efficient phosphorus control, this method can also effectively inhibit the activity of phosphate-solubilizing bacteria and reduce the secondary release of phosphorus, thus providing a new technical solution for the treatment of endogenous pollution in coastal rivers and lakes.

[0008] To achieve the above object, the present invention provides a composition for controlling phosphorus release and enriching phosphate-solubilizing bacteria in coastal river and lake bottom mud. The composition is characterized in that the composition contains four components: calcium oxide, magnesium chloride, ferric chloride and aluminum sulfate. Preferably, the weight ratio of the four components is 35%-40%, the magnesium chloride is 5%-10%, the ferric chloride is 10%-20%, and the aluminum sulfate is 30%-45%.

[0009] The present invention also provides a medicament for controlling phosphorus release and phosphate-solubilizing bacteria enrichment in coastal river and lake bottom mud, characterized in that it contains the composition.

[0010] Furthermore, the agent is modified with silicon dioxide.

[0011] Furthermore, the agent is modified with silica, which means that ethyl orthosilicate or sodium silicate is used as a silicon source and hydrolyzed under alkaline conditions to form a uniform silica sol; then, the agent particles are uniformly dispersed in the silica sol and ultrasonically stirred to promote the deposition reaction of the silica sol on the surface of the particles; and then dried and sintered at low temperature to form a dense silica thin layer coating the particles.

[0012] Furthermore, the pH of the alkaline condition is 8.5-9.2.

[0013] Furthermore, the ultrasonic stirring has an ultrasonic frequency of 20-40 kHz and a stirring condition of 100-300 rpm.

[0014] Furthermore, the deposition reaction time is 10-40 minutes.

[0015] Furthermore, the drying refers to drying at 60-80° C. for 5-8 hours, and the low-temperature sintering refers to sintering at 300-500° C. for 1-3 hours.

[0016] The present invention also claims that the composition and the medicament have the effect of controlling the release of phosphorus from the sediments of coastal rivers and lakes and the enrichment of phosphate-solubilizing bacteria.

[0017] This invention aims to address the issues of phosphorus release from river and lake sediments and ineffective phosphorus control in hypersaline environments during endogenous pollution control. With the core goals of achieving efficient phosphorus control, stabilizing environmental pH, and enhancing salt tolerance, this invention proposes a multi-component agent optimization and silica coating modification technology. By combining comprehensive experiments with theoretical modeling, this invention achieves optimal agent ratios and long-term stability. Furthermore, considering the unique impact of hypersaline environments in coastal rivers and lakes on agent performance, this invention further proposes a silica coating modification method. Silica sol is prepared via a sol-gel method, using ethyl orthosilicate or sodium silicate as the silicon source. Hydrolysis under alkaline conditions forms a uniform silica sol solution. The optimized agent particles are then uniformly dispersed in the silica sol. Heating or ultrasonic agitation is used to promote silica sol deposition on the particle surfaces. After drying at 60-80°C and sintering at 300-500°C, the particles are coated with a dense, thin silica layer. This modification method effectively enhances the agent's stability and salt tolerance. In a high-salt environment, this coating layer can reduce the direct competitive interference of salt ions such as sodium ions and potassium ions on the active components of the agent, while providing additional phosphate adsorption sites to further enhance the phosphorus fixation capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the response diagram of the pH level of the overlying water under the application of traditional calcium-based phosphorus removal agents.

[0019] Figure 2 This is a diagram of phosphorus release flux in sediment under different salinity conditions.

[0020] Figure 3 is the weight map of environmental factors.

[0021] Figure 4 This is a characteristic diagram of the relative abundance of typical phosphate-solubilizing bacteria in the sediment without the addition of pesticides and with the addition of pesticides.

[0022] Figure 5 This is a comparison chart of phosphorus control efficiency before and after agent modification. DETAILED DESCRIPTION

[0023] Below in detail embodiments of the present invention, the example of described embodiment is shown in the accompanying drawings, wherein identical or similar reference numerals represent identical or similar elements or elements with identical or similar functions throughout. The embodiment described below by reference to the accompanying drawings is exemplary, is intended to be used for explaining the present invention, and is not to be construed as limiting the present invention. In the embodiment, those not indicating specific techniques or conditions are carried out according to the technology or conditions described in the document in this area or according to the product specification. Reagents used or instruments not indicating manufacturers are conventional products that can be obtained commercially.

[0024] Example 1

[0025] This study used calcium oxide (A), magnesium chloride (B), ferric chloride (C), and aluminum sulfate (D) as the foundation for an experimental system using a central coincidence design. Sediment phosphorus release control efficiency and overlying water pH were used as key control factors, and 30 experimental protocols were developed and implemented. The experiment, through long-term monitoring (30 days), generated multiple sets of data on phosphorus release control efficiency and overlying water pH (see Table 1). The experimental data were then systematically evaluated using analysis of variance to determine a model approach suitable for fitting the data relationships.

[0026] Table 1 30 experimental plans and their results

[0027]

[0028]

[0029] Through the analysis and verification of the experimental data in Table 1, the present invention established a mathematical model for pH level and phosphorus release control efficiency, which are respectively

[0030] pH=15.01*A+11.2*B+3.08*C+3.99*D;

[0031] Phosphorus release control efficiency = (93.27*A-21.43*B+35.45*C+58.44*D) / 100.

[0032] Wherein A, B, C, and D are calcium oxide, magnesium chloride, ferric chloride, and aluminum sulfate, respectively. The units are all percentages (%) calculated by mass; the unit of phosphorus release control efficiency is %.

[0033] Based on the model, the experimental combination was optimized using a hill climbing algorithm, determining the optimal composition ratio range: calcium oxide (A) was controlled at 35%-40% by weight, magnesium chloride (B) was controlled at 5%-10%, ferric chloride (C) was 10%-20%, and aluminum sulfate (D) was 30%-45%. This optimized ratio effectively controls phosphorus release from sediments and improves phosphorus fixation capacity, while maintaining the overlying water pH within an ecologically safe range (8.0-8.8), avoiding the risk of pH loss caused by a single agent.

[0034] On this basis, the present invention combines the activity study of typical phosphate-solubilizing bacteria to further study the control requirements of the agent components. Phosphate-solubilizing bacteria can convert insoluble phosphorus compounds into soluble phosphate radicals, and their activity is significantly affected by the environmental pH. By studying the response characteristics of phosphate-solubilizing bacteria under different pH conditions, see Table 2. It was found that when the pH range is controlled above 8.0, phosphate-solubilizing bacteria of the genera Actinomycetes and Fungi are difficult to survive, and as the pH increases, the abundance of phosphate-solubilizing bacteria of the genera Pseudomonas and Bacillus will significantly decrease, thereby having the potential to inhibit the re-release of phosphorus in the sediment. Combined with the surface water control requirements, the present invention proposes that the pH level of the agent should be controlled between 8.0-8.8, so that the agent has comprehensive advantages in inhibiting the activity of phosphate-solubilizing bacteria, fixing sediment phosphorus and maintaining the ecological safety of water bodies.

[0035] Phosphate-solubilizing bacteria are a type of microorganism that can convert insoluble phosphorus compounds into soluble phosphate radicals. Their activity may cause the phosphorus fixed in the sediment to be released again, thereby enhancing the release of phosphorus in the sediment. Phosphate-solubilizing bacteria rely on organic acids to dissolve phosphates, and an alkaline environment will neutralize organic acids, reducing their effectiveness, thereby affecting the ability of these bacteria to obtain energy and forming an inhibitory effect. The research team found that when the relative abundance of the typical phosphate-solubilizing bacteria - Bacillus is greater than 1.1%, there is a significant linear relationship between the relative abundance of this type of bacteria and phosphorus release. The relationship between the two can be expressed by the following formula:

[0036] Y1=12.344562*X+Y

[0037] Among them, Y1 is the phosphorus release flux after coupling the information of phosphate-solubilizing bacteria (unit: mg / kg / day), X is the relative abundance of Bacillus (unit: %), and Y is the phosphorus release flux obtained by the environmental variables mentioned above (unit: mg / kg / day).

[0038] The results are shown in Table 2 and Figure 1 .

[0039] Table 2 Relative abundance of Pseudomonas and Bacillus phosphate-solubilizing bacteria at different pH

[0040] pH 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Bacillus 6.21％ 9.34％ 7.65％ 4.77％ 0.75％ 0.12％ 0.32％ Pseudomonas 11.20％ 4.56％ 8.23％ 5.21％ 0.87％ 0.57％ 0.14％

[0041] Example 2: Experiment on the effect of different salinities on phosphorus release flux in sediment

[0042] Sediment samples were collected at 46 measuring points in a coastal lake. The sediment sampling process involves sinking the sediment collector to the bottom of the water body and then quickly extracting the sample to maintain the original structure of the sediment. After sampling, the sediment samples are stored in low-temperature sealed containers to prevent the influence of oxygen and microbial degradation. The 46 samples were then tested in the laboratory to determine the release flux of phosphorus from the sediment in salt-free overlying water. The study first used potassium dihydrogen phosphate to prepare 0.05-0.2 mg / L phosphorus solutions. Subsequently, they were grouped according to a water-soil ratio of 90:1 (i.e. 45 mL: 0.5 g). Each group mixed the above-mentioned sediment samples and phosphoric acid solution, and after shaking at 25°C for 48 hours, they were separated by centrifugation (at a speed of 10,000 rpm for 10 minutes). The supernatant was then filtered through a 0.45 μm fiber filter membrane and the total phosphorus concentration was determined according to the standard method "Water Quality—Determination of Total Phosphorus—Ammonium Molybdate Spectrophotometry (GB 11893-89)" in the "Water and Wastewater Monitoring and Analysis Methods (4th Edition)." To investigate the impact of salinity on the Binhai Lake Reservoir, the phosphorus release flux of the 46 sediment samples described above in the saline overlying water was measured. This method involved preparing solutions with salinities of 5-20‰ using sodium chloride. This solution and potassium dihydrogen phosphate were then used to prepare phosphorus solutions with concentrations of 0.05-0.2 mg / L. Sediment samples of varying concentrations were mixed with the phosphorus solution at a water-to-soil ratio of 90:1 (i.e., 45 mL:0.5 g). The samples were then divided into groups and shaken at 25°C for 48 hours. The mixtures were then separated by centrifugation (10,000 rpm for 10 minutes) and filtered through a 0.45 μm fiber membrane. The supernatant was then extracted using the same standard method as above. The total phosphorus concentration in the solution was determined by spectrophotometry and divided by mass to obtain the release flux. Figure 2 This is a diagram of the phosphorus release flux in sediment under different salinity conditions. The vertical axis is the sample number, the horizontal axis is the sample grouping, and the picture is a heat map. The redder the color, the greater the release amount, and the bluer the color, the less the release.

[0043] The effect of salinity on phosphorus release was evaluated by combining variance inflation factor analysis with the Boruta algorithm. Figure 3 . Figure 3 This is the weighted graph of environmental factors. The vertical axis represents the environmental factors, and the horizontal axis represents the weight coefficient, which is used to compare the size of the factors. The larger the value, the greater the impact of the factor. Figure 3 It can be seen that the presence of salinity significantly promotes the release of phosphorus, and its influence (0.01) is second only to the phosphorus concentration in the sediment (0.02).

[0044] Example 3: Preparation of medicament

[0045] Composition formula: 39% calcium oxide, 8% magnesium chloride, 15% ferric chloride, and 38% aluminum sulfate. (Weight percentage)

[0046] Preparation method:

[0047] Using ethyl orthosilicate or sodium silicate as the silicon source, it is hydrolyzed under alkaline conditions (pH 8.5-9.2) to form a uniform silica sol;

[0048] The particles of the above composition are uniformly dispersed in the above silica sol, and ultrasonic stirring (ultrasonic frequency of 20-40 kHz, stirring conditions of 100-300 rpm) is used to promote the deposition reaction of silica sol on the surface of the particles; the deposition reaction time is 10-40 minutes;

[0049] Re-drying: Dry at 60-80℃ for 5-8 hours,

[0050] Low temperature sintering: 300-500℃ sintering for 1-3 hours,

[0051] A dense thin layer of silica is formed to coat the particles.

[0052] Comparative Example 1:

[0053] Composition formula: 39% calcium oxide, 8% magnesium chloride, 15% ferric chloride, and 38% aluminum sulfate. (Weight percentage)

[0054] Preparation method: Mix well and then dry at 60-80℃ for 1-3 hours.

[0055] Example 4: Preparation of medicament

[0056] Composition formula: 35% calcium oxide, 10% magnesium chloride, 10% ferric chloride, 45% aluminum sulfate. (Weight percentage)

[0057] Preparation method: same as Example 3.

[0058] Example 5: Preparation of medicament

[0059] Composition formula: 38% calcium oxide, 5% magnesium chloride, 17% ferric chloride, and 40% aluminum sulfate. (Weight percentage)

[0060] Preparation method: same as Example 3.

[0061] Example 6: Preparation of medicament

[0062] Composition formula: 40% calcium oxide, 10% magnesium chloride, 20% ferric chloride, and 30% aluminum sulfate. (Weight percentage)

[0063] Preparation method: same as Example 3.

[0064] Example 7 Effect Test

[0065] 1. A confirmatory analysis was conducted based on the model, and it was found that the model has a good effect and can reflect the response trend of phosphorus release control efficiency and overlying water pH.

[0066] Table 3 Comparison of effect experimental results

[0067]

[0068] Note: The prediction formula is pH = 15.01*A+11.2*B+3.08*C+3.99*D;

[0069] Phosphorus release control efficiency = (93.27*A-21.43*B+35.45*C+58.44*D) / 100.

[0070] It can be seen that the predicted results are close to the actual detection results.

[0071] 2. After the application of the above-mentioned components, the research team compared the relative abundance characteristics of typical phosphate-solubilizing bacteria in the bottom mud without the addition of the agent and the agent (obtained in Example 3). The results are shown in Figure 4 and Table 4. The results showed that after the addition of the agent (the addition amount was controlled at 500 g / m2 and the measurement was performed 28 days after application), neither Aspergillus nor Penicillium were detected in the sediment, while Bacillus and Pseudomonas were significantly reduced after the addition of the agent compared with those without the agent. This result shows that the agent does have the ability to significantly inhibit the enrichment of phosphate-solubilizing bacteria.

[0072] Table 4 Figure 4 Corresponding data table

[0073] No added drug group Drug addition group Aspergillus 0.10％ 0 Penicillium 0.38％ 0 Bacillus 4.56％ 2.10％ Pseudomonas 7.93％ 3.44％

[0074] 3. Based on silica coating modification, the study found that for salt-free water bodies, the phosphorus control effect of the agent was slightly reduced, but it still maintained a high similarity with the unmodified agent, and the reduction in effect was not obvious. However, as the salinity continued to increase, the silica coupling modification strategy played a significant role. Under salinity conditions of 10‰, 20‰ and 30‰, the phosphorus control efficiency of the silica-modified agent (obtained in Example 3) was 59.88%, 56.27% and 57.22%, respectively, while the phosphorus control efficiency of the unmodified agent (obtained in Comparative Example 1) dropped significantly to 44.21%, 35.61% and 33.32%, respectively. Figure 5 .

[0075] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A composition for controlling phosphorus release from coastal river and lake sediments and enriching phosphate-solubilizing bacteria, characterized in that: The composition contains four components: calcium oxide, magnesium chloride, ferric chloride and aluminum sulfate. Preferably, the weight ratio of the four components is 35%-40%, magnesium chloride is 5%-10%, ferric chloride is 10%-20%, and aluminum sulfate is 30%-45%.

2. A medicament for controlling phosphorus release and phosphate-solubilizing bacteria accumulation in coastal river and lake sediments, characterized in that: Containing the composition according to claim 1.

3. The medicament according to claim 2, wherein The agent is modified with silicon dioxide.

4. The medicament according to claim 3, wherein The agent is modified with silica by using ethyl orthosilicate or sodium silicate as a silicon source and hydrolyzing it under alkaline conditions to form a uniform silica sol; then, the agent particles are uniformly dispersed in the silica sol and ultrasonically stirred to promote the deposition reaction of the silica sol on the surface of the particles; and then dried and sintered at low temperature to form a dense silica thin layer-coated particles.

5. The medicament according to claim 4, characterized in that The pH of the alkaline condition is 8.5-9.

2.

6. The drug according to claim 4, characterized in that The ultrasonic stirring has an ultrasonic frequency of 20-40 kHz and a stirring condition of 100-300 rpm.

7. The pharmaceutical agent according to claim 4, characterized in that The deposition reaction time is 10-40 minutes.

8. The drug according to claim 4, characterized in that The drying refers to drying at 60-80° C. for 5-8 hours, and the low-temperature sintering refers to sintering at 300-500° C. for 1-3 hours.

9. The composition according to claim 1 and the medicament according to claims 2 to 8 have the effect of controlling the release of phosphorus from the sediments of coastal rivers and lakes and the enrichment of phosphate-solubilizing bacteria.

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