A modified sepiolite-iron-reducing bacteria composite bacterial agent and its preparation method and application

Abstract

This invention discloses a modified sepiolite-iron-reducing bacteria composite agent, its preparation method, and its application, belonging to the field of water pollution remediation technology. The modified sepiolite-iron-reducing bacteria composite agent is composed of modified sepiolite and iron-reducing bacteria; the modified sepiolite is formed by loading iron-magnesium co-hydroxide onto the sepiolite. This composite agent exhibits high selectivity and good removal effect for phosphorus in phosphorus-polluted water bodies, facilitating the achievement of phosphorus removal in a relatively short time, and enabling the recovery of phosphorus resources in a reusable form, generating economic added value.

Description

Technical Field

[0001] The invention relates to a phosphorus removal agent, in particular to a modified sepiolite-iron-reducing bacteria composite bacterial agent, further relates to a preparation method of the modified sepiolite-iron-reducing bacteria composite bacterial agent, and to application of the modified sepiolite-iron-reducing bacteria composite bacterial agent in phosphorus removal and recovery in phosphorus-contaminated water bodies, belonging to the technical field of water pollution remediation. Background Art

[0002] With the increasing amount of urban domestic sewage discharge, the concentration of pollutants such as nitrogen and phosphorus in natural waters such as rivers, lakes and ditches far exceeds the environmental carrying capacity and self-purification capacity, thus changing the physical and chemical properties of natural waters. The occurrence of algal blooms may even cause seasonal or year-round black and smelly phenomena in natural waters, deteriorating the living environment and endangering human health. Phosphorus is an important element for the growth of plants and animals, but high phosphorus content in water bodies is an important cause of eutrophication of water bodies. Eutrophication of water bodies will not only cause a sharp increase in algae and algal blooms, but also cause aquatic organisms to lack oxygen. Eventually, the water body may turn black and smelly, further deteriorating the water quality. It is generally believed that when the phosphorus content in the water reaches 0.02 mg / L, the water body is in a eutrophic state. Therefore, how to use efficient and green methods to remove phosphorus from water bodies is the key.

[0003] There are many phosphorus removal technologies at present. Adsorption method, as a method that can enrich phosphorus in adsorbent, has great advantages in phosphorus recycling and utilization, and has the characteristics of simple operation and good treatment effect. Clay minerals not only have a certain phosphate adsorption capacity, but also can be used as slow-release fertilizer for soil after adsorption and phosphorus removal, or the adsorbed phosphorus can be recovered and used in industry and agriculture. Sepiolite is a fibrous magnesium-rich silicate mineral, a chain-layered structure mineral composed of two layers of silicon-oxygen tetrahedrons sandwiched between a layer of magnesium-oxygen octahedrons, with the characteristics of large specific surface area and rich active sites. However, natural sepiolite has a low adsorption capacity for phosphate, and sepiolite is usually required to be physically or chemically modified to improve its phosphorus removal capacity. Among them, loading sepiolite with metal is one of the most effective methods for chemical modification of sepiolite. By introducing metal (hydride) oxides that can bind to phosphate into sepiolite, the sepiolite composite material retains the performance advantages of natural sepiolite while also having the high selective binding capacity of metal (hydride) oxides to phosphate. However, the phosphorus adsorbed by the modified sepiolite material in the prior art is difficult to be effectively recovered and reused. Summary of the invention

[0004] In order to achieve the above technical objectives, the first object of the present invention is to provide a modified sepiolite-iron-reducing bacteria composite bacterial agent, which has good removal and purification effect on phosphorus in phosphorus-contaminated water bodies and high selectivity, is conducive to achieving the purpose of phosphorus removal in a relatively short time, and can recover the adsorbed phosphorus resources in a reusable form, thereby generating economic added value.

[0005] The second object of the present invention is to provide a method for preparing a modified sepiolite-iron-reducing bacteria composite agent. The preparation method has the advantages of simple operation, short process flow, low cost, etc., and is conducive to industrial production.

[0006] The third object of the present invention is to provide an application of a modified sepiolite-iron-reducing bacteria composite bacterial agent in the removal and recovery of phosphorus in phosphorus-contaminated water bodies. It has high phosphorus removal efficiency and fast speed, and can remove phosphorus in a long-lasting and effective manner, and can convert phosphorus into phosphorus resources with higher added value for recovery and reuse.

[0007] In order to achieve the above technical purpose, the present invention provides a modified sepiolite-iron-reducing bacteria composite bacterial agent, which is composed of modified sepiolite and iron-reducing bacteria; the modified sepiolite is composed of iron-magnesium co-hydroxide loaded on sepiolite.

[0008] The modified sepiolite-iron-reducing bacteria composite bacterial agent of the present invention includes modified sepiolite and iron-reducing bacteria. The modified sepiolite uses sepiolite as a carrier to load iron-magnesium co-hydroxide components. The sepiolite mineral has the characteristics of large specific surface area and rich active sites, and is rich in silicon, magnesium, calcium and some elements such as iron and aluminum. It itself has good phosphorus removal activity. Using sepiolite mineral as a carrier can achieve a highly dispersed load of magnesium hydroxide and iron hydroxide active ingredients, and give full play to its phosphorus removal activity. Iron-magnesium co-hydroxide is used as an active ingredient to modify sepiolite. On the one hand, iron ions and magnesium ions form ≡O-Fe bonds and ≡O-Mg bonds by bonding with ≡OH in sepiolite, so that magnesium hydroxide and iron hydroxide active ingredients are generated in situ on sepiolite, and trivalent iron ions have Lewis acidity and strong binding ability to phosphate anions, while metal magnesium oxide is positively charged and can be combined with phosphorus by electrostatic attraction and surface hydroxyl coordination, thereby improving its effect of adsorbing phosphorus. On this basis, iron-reducing bacteria are introduced, which can reduce the iron ions released by the modified sepiolite into ferrous ions, which combine with phosphate to form ferrous phosphate (blue iron ore) precipitate, and can also partially reduce the ferric phosphate into ferrous phosphate. The ferrous phosphate with higher purity can be used as a raw material for lithium ferrous phosphate, and the modified sepiolite-iron-reducing bacteria composite agent after adsorbing phosphorus can be reused as a slow-release phosphate fertilizer. At the same time, compared with the directly added iron source, the biogenic Fe (II) obtained by iron-reducing bacteria has multiple forms such as adsorption, complexation, and structure, and has a high removal rate of phosphorus in water, which can further improve the phosphorus removal effect of modified sepiolite.

[0009] As a preferred solution, the total mass of iron and magnesium in the iron-magnesium co-hydroxide is 0.05 to 0.6 times the mass of sepiolite. When the content of iron and magnesium is too high, active ingredients such as iron hydroxide or iron-magnesium co-hydroxide agglomerate and reduce the specific surface area, thereby reducing the removal rate of phosphorus in the water body. When the content of iron and magnesium is too low, the content of active ingredients such as iron hydroxide or iron-magnesium co-hydroxide is too low, which also reduces the removal efficiency of phosphorus in the water body. Therefore, the loading amount of active ingredients on the surface of sepiolite needs to be appropriate.

[0010] As a preferred solution, the mass ratio of magnesium to iron in the iron-magnesium co-hydroxide is (0.1~1):1; the modified sepiolite uses iron-magnesium co-hydroxide as an active ingredient, and its adsorption effect on phosphorus is better than that of a single iron hydroxide active ingredient. As the amount of magnesium added increases, the effect of modified sepiolite on adsorbing inorganic phosphorus tends to increase first and then decrease. When the mass ratio of magnesium to iron reaches 0.2:1, the modified sepiolite has the best effect on adsorbing inorganic phosphorus. Preferably, the mass ratio of magnesium to iron in the iron-magnesium co-hydroxide is (0.1~0.3):1.

[0011] As a preferred solution, the cell density of iron-reducing bacteria in the modified sepiolite-iron-reducing bacteria composite agent is 10 6 ~10 8 cfu / mL.

[0012] As a preferred embodiment, the iron-reducing bacteria is selected from Shewanella oneidensis MR-1. Shewanella oneidensis MR-1 The Chinese name is: Oneida Lake Shewanella MR-1, which is a conventional commercial product.

[0013] The present invention also provides a method for preparing a modified sepiolite-iron-reducing bacteria composite bacterial agent, which comprises adding sepiolite to an aqueous solution containing iron ions and magnesium ions, adjusting the pH to alkaline to carry out a hydrolysis precipitation reaction, and after the reaction is completed, filtering, washing, drying and grinding are carried out in sequence to obtain the modified sepiolite; after the modified sepiolite is sterilized, it is mixed with iron-reducing bacteria and cultured in a culture medium to obtain the modified sepiolite.

[0014] As a preferred solution, the concentration of iron ions in the aqueous solution containing iron ions and magnesium ions is 1.25-7.5 g / L, and the concentration of magnesium ions is 1.25-7.5 g / L.

[0015] As a preferred solution, the concentration of the sepiolite added to the aqueous solution containing iron ions and magnesium ions is measured at 10-25 g / L. The magnesium ions in the aqueous solution containing iron ions and magnesium ions are provided by water-soluble magnesium salts, such as magnesium chloride, magnesium nitrate, etc. The iron ions are provided by water-soluble iron salts, such as iron chloride, iron nitrate, iron sulfate, etc.

[0016] As a preferred solution, the conditions of the hydrolysis precipitation reaction are: pH is adjusted to 10-12, and stirred at room temperature for 2-12 h. The pH adjustment solution is a 1 mol / L NaOH solution. The pH is further preferably adjusted to 11-11.5. When the pH increases, the adsorption efficiency of the prepared modified sepiolite for phosphorus gradually increases. When the pH is above 11.5, the adsorption efficiency of the prepared modified sepiolite for phosphorus remains basically unchanged. The stirring reaction time is further preferably 3-5 h.

[0017] As a preferred embodiment, the culture medium is LB culture medium.

[0018] As a preferred solution, the culture time is 1 to 2 days. After mixed culture, the iron-reducing bacteria and the modified sepiolite can be perfectly compounded.

[0019] The present invention also provides an application of a modified sepiolite-iron-reducing bacteria composite bacterial agent, which is used for removing and recovering phosphorus in phosphorus-contaminated water bodies.

[0020] As a preferred solution, the dosage of the modified sepiolite-iron-reducing bacteria composite agent in the phosphorus-contaminated water body is 1 wt%~5 wt%.

[0021] As a preferred solution, the concentration of inorganic phosphorus in the phosphorus-contaminated water body is greater than 0.05 mg / L.

[0022] As a preferred solution, the sepiolite is an unpurified natural sepiolite mineral, which is rich in silicon, magnesium, calcium, and has some iron and aluminum. It has a better phosphorus removal effect than purified sepiolite mineral, and the price of natural sepiolite is lower than that of purified sepiolite.

[0023] The principle of the modified sepiolite-iron-reducing bacteria composite bacterial agent of the present invention for repairing phosphorus-contaminated water bodies is as follows: 1) natural sepiolite mineral is used as a carrier material to combine iron or iron and magnesium in the form of hydroxide with sepiolite by a coprecipitation method, which can serve as a binding site for phosphorus, thereby improving the adsorption efficiency of sepiolite for phosphorus and better repairing phosphorus-contaminated water bodies. The modified sepiolite can continuously and efficiently adsorb phosphorus in water bodies through chemical precipitation, ligand exchange and electrostatic attraction. 2) The modified sepiolite is mainly aimed at removing phosphorus from phosphorus-contaminated water bodies, and its surface is positively charged, and phosphate can be adsorbed by electrostatic attraction. 3) The addition of iron-reducing bacteria can reduce the iron element in the modified sepiolite to generate blue iron ore with higher economic value. 4) Compared with the direct addition of iron source, the biogenic Fe(II) generated by iron-reducing bacteria has multiple forms such as adsorption state, complex state, and structural state, and has a high removal rate of phosphorus in water bodies. The blue iron ore generated by biogenic Fe(II) has good stability, which is conducive to the removal and recovery of phosphorus. The composite bacterial agent of the present invention greatly improves the removal rate of phosphorus in water bodies, and is helpful to repair phosphorus-polluted water bodies.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0025] The modified sepiolite-iron-reducing bacteria composite bacterial agent of the present invention effectively solves the problem of phosphorus removal and recovery in phosphorus-contaminated water bodies, and can repair phosphorus-contaminated water bodies and purify water quality in an efficient and green manner.

[0026] The method for preparing the modified sepiolite-iron-reducing bacteria composite bacterial agent of the present invention has the advantages of simple operation, short processing flow, low cost and the like.

[0027] The modified sepiolite-iron-reducing bacteria composite bacterial agent provided by the present invention modifies the natural sepiolite ore by iron and magnesium, improves the phosphorus adsorption efficiency of sepiolite, can selectively remove inorganic phosphorus in phosphorus-contaminated water bodies, and has strong resistance to external interference. The unique chain layered structure of sepiolite provides a living space guarantee for iron-reducing bacteria, and multiple isolation spaces are formed between sepiolites, which reduces environmental stress, provides stable living conditions for iron-reducing bacteria, and improves the activity of iron-reducing bacteria. The interaction between modified sepiolite and iron-reducing bacteria can further improve the removal rate of phosphorus in water bodies, and converts adsorbed phosphorus into blue iron ore with higher added value, creating new value. The modified sepiolite-iron-reducing bacteria composite bacterial agent realizes the selective removal and recovery of phosphorus through chemical precipitation, electrostatic adsorption, ligand exchange and other effects. The modified sepiolite adsorbed with phosphorus can be used as a slow-release fertilizer for agricultural soil, and the blue iron ore formed can be used as a raw material for producing batteries. Biogenic Fe (II) is formed by iron-reducing bacteria reducing iron, and its reducibility has a great influence on pollutant removal. Compared with the direct addition of iron sources, biogenic Fe(II) has multiple forms such as adsorption, complexation, and structural state. It has a high removal rate of phosphorus in water and has good application prospects in the field of water body remediation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is an X-ray diffraction analysis (XRD) diagram of the iron-magnesium modified sepiolite-iron-reducing bacteria composite bacterial agent prepared in Example 1 before and after repairing phosphorus-contaminated water.

[0029] Figure 2 This is an X-ray photoelectron spectroscopy analysis (XPS) diagram of the sepiolite-iron-reducing bacteria composite agent prepared in Example 1 after repairing phosphorus-contaminated water. DETAILED DESCRIPTION

[0030] The following specific embodiments are intended to further illustrate the contents of the present invention in detail in conjunction with the drawings of the specification, and the following specific embodiments do not limit the protection scope of the claims.

[0031] In the following examples, the Oneida Lake Shewanella MR-1 bacterial agent was purchased from the China Industrial Microbial Culture Collection Management Center. The cell density of iron-reducing bacteria in the modified sepiolite-iron-reducing bacteria composite bacterial agent was about 10 7 cfu / mL.

[0032] Example 1

[0033] (1) A 200-mesh natural Xiangtan sepiolite ore (main components and mass content: SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) was selected as the substrate.

[0034] (2) According to the mass ratio of magnesium to iron of 0.2:1 and the total mass of magnesium and iron to sepiolite of 0.3:1, FeCl3·6H2O and MgCl2·6H2O were mixed with sepiolite to make up to 30 mL and stirred for 30 min to obtain a mixed solution. The pH of the mixed solution was adjusted to 11.5 with 1 mol / L NaOH solution and stirred for 4 h. The solution was filtered and washed until neutral to obtain a modified sepiolite filter cake.

[0035] (3) The filter cake in (2) was placed in an oven and dried at 60°C for 8 h. After grinding and sieving through 200 mesh, the modified sepiolite was obtained. The modified sepiolite, the bacterial culture of Oneida Lake Shewanella MR-1 and the LB liquid culture medium were mixed evenly (the bacterial culture to the liquid culture medium = 1:20; v / v), and the culture was continued for 2 days to obtain the modified sepiolite-iron-reducing bacteria composite bacterial agent.

[0036] Example 2

[0037] (1) A 200-mesh natural Xiangtan sepiolite ore (main components and mass content: SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) was selected as the substrate.

[0038] (2) According to the mass ratio of magnesium to iron of 0.1:1 and the total mass of magnesium and iron to sepiolite of 0.3:1, FeCl3·6H2O and MgCl2·6H2O were mixed with sepiolite to make up to 30 mL and stirred for 30 min to obtain a mixed solution. The pH of the mixed solution was adjusted to 11.5 with 1 mol / L NaOH solution and stirred for 4 h. The solution was filtered and washed until neutral to obtain a modified sepiolite filter cake.

[0039] (3) The filter cake in (2) was placed in an oven and dried at 60°C for 8 h. After grinding and sieving through 200 mesh, the modified sepiolite was obtained. The modified sepiolite, the bacterial culture of Oneida Lake Shewanella MR-1 and the LB liquid culture medium were mixed evenly (the bacterial culture to the liquid culture medium = 1:20; V / V), and the culture was continued for 2 days to obtain the modified sepiolite-iron-reducing bacteria composite bacterial agent.

[0040] Example 3

[0041] (1) A 200-mesh natural Xiangtan sepiolite ore (main components and mass content: SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) was selected as the substrate.

[0042] (2) According to the mass ratio of magnesium to iron of 0.5:1 and the total mass of magnesium and iron to sepiolite of 0.3:1, FeCl3·6H2O and MgCl2·6H2O were mixed with sepiolite to make up to 30 mL and stirred for 30 min to obtain a mixed solution. The pH of the mixed solution was adjusted to 11.5 with 1 mol / L NaOH solution and stirred for 4 h. The solution was filtered and washed until neutral to obtain a modified sepiolite filter cake.

[0043] (3) The filter cake in (2) was placed in an oven and dried at 60°C for 8 h. After grinding and sieving through 200 mesh, the modified sepiolite was obtained. The modified sepiolite, the bacterial culture of Oneida Lake Shewanella MR-1 and the LB liquid culture medium were mixed evenly (the bacterial culture to the liquid culture medium = 1:20; V / V), and the culture was continued for 2 days to obtain the modified sepiolite-iron-reducing bacteria composite bacterial agent.

[0044] Example 4

[0045] (1) A 200-mesh natural Xiangtan sepiolite ore (main components and mass content: SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) was selected as the substrate.

[0046] (2) According to the mass ratio of magnesium to iron of 0.2:1 and the total mass of magnesium and iron to sepiolite of 0.05:1, FeCl3·6H2O and MgCl2·6H2O were mixed with sepiolite to make up to 30 mL and stirred for 30 min to obtain a mixed solution. The pH of the mixed solution was adjusted to 11.5 with 1 mol / L NaOH solution and stirred for 4 h. The solution was filtered and washed until neutral to obtain a modified sepiolite filter cake.

[0047] (3) The filter cake in (2) was placed in an oven and dried at 60°C for 8 h. After grinding and sieving through 200 mesh, the modified sepiolite was obtained. The modified sepiolite, the bacterial culture of Oneida Lake Shewanella MR-1 and the LB liquid culture medium were mixed evenly (the bacterial culture to the liquid culture medium = 1:20; V / V), and the culture was continued for 2 days to obtain the modified sepiolite-iron-reducing bacteria composite bacterial agent.

[0048] Example 5

[0049] (1) A 200-mesh natural Xiangtan sepiolite ore (main components and mass content: SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) was selected as the substrate.

[0050] (2) According to the mass ratio of magnesium to iron of 0.2:1 and the total mass of magnesium and iron to sepiolite of 0.5:1, FeCl3·6H2O and MgCl2·6H2O were mixed with sepiolite to make up to 30 mL and stirred for 30 min to obtain a mixed solution. The pH of the mixed solution was adjusted to 11.5 with 1 mol / L NaOH solution and stirred for 4 h. The solution was filtered and washed until neutral to obtain a modified sepiolite filter cake.

[0051] (3) The filter cake in (2) was placed in an oven and dried at 60°C for 8 h. After grinding and sieving through 200 mesh, the modified sepiolite was obtained. The modified sepiolite, the bacterial culture of Oneida Lake Shewanella MR-1 and the LB liquid culture medium were mixed evenly (the bacterial culture to the liquid culture medium = 1:20; V / V), and the culture was continued for 2 days to obtain the modified sepiolite-iron-reducing bacteria composite bacterial agent.

[0052] Example 6

[0053] (1) A 200-mesh natural Xiangtan sepiolite ore (main components and mass content: SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) was selected as the substrate.

[0054] (2) According to the mass ratio of iron to sepiolite of 0.3:1, FeCl3·6H2O and sepiolite were mixed to a volume of 30 mL and stirred for 30 min to obtain a mixed solution. The pH of the mixed solution was adjusted to 11.5 with 1 mol / L NaOH solution, and then stirred for 4 h. The mixed solution was filtered and washed until neutral to obtain a modified sepiolite filter cake.

[0055] (3) The filter cake in (2) was placed in an oven and dried at 60°C for 8 h. After grinding and sieving through 200 mesh, the modified sepiolite was obtained. The modified sepiolite, the bacterial culture of Oneida Lake Shewanella MR-1 and the LB liquid culture medium were mixed evenly (the bacterial culture to the liquid culture medium = 1:20; V / V), and the culture was continued for 2 days to obtain the modified sepiolite-iron-reducing bacteria composite bacterial agent.

[0056] Comparative Example 1

[0057] (1) A 200-mesh natural Xiangtan sepiolite ore (main components and mass content: SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) was selected as the substrate.

[0058] (2) According to the mass ratio of magnesium to sepiolite of 0.3:1, MgCl2·6H2O and sepiolite were mixed to a volume of 30 mL and stirred for 30 min to obtain a mixed solution. The pH of the mixed solution was adjusted to 11.5 with 1 mol / L NaOH solution, and then stirred for 4 h. The solution was filtered and washed until neutral to obtain a modified sepiolite filter cake.

[0059] (3) The filter cake in (2) was placed in an oven and dried at 60°C for 8 h. After grinding and sieving through 200 mesh, the modified sepiolite was obtained. The modified sepiolite, the bacterial culture of Oneida Lake Shewanella MR-1 and the LB liquid culture medium were mixed evenly (the bacterial culture to the liquid culture medium = 1:20; V / V), and the culture was continued for 2 days to obtain the modified sepiolite-iron-reducing bacteria composite bacterial agent.

[0060] Comparative Example 2

[0061] (1) A 200-mesh natural Xiangtan sepiolite ore (main components and contents SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) was selected as the substrate.

[0062] (2) According to the mass ratio of magnesium to iron of 0.2:1 and the total mass of magnesium and iron to sepiolite of 0.3:1, FeCl3·6H2O and MgCl2·6H2O were mixed with sepiolite to make up to 30 mL and stirred for 30 min to obtain a mixed solution. The pH of the mixed solution was adjusted to 11-11.5 with 1 mol / L NaOH solution and stirred for 4 h. The solution was filtered and washed until neutral to obtain a modified sepiolite filter cake.

[0063] (3) The filter cake in (2) was placed in an oven and dried at 60°C for 8 h. After grinding and sieving through 200 mesh, modified sepiolite was obtained.

[0064] Example 7

[0065] The modified sepiolite-iron-reducing bacteria composite bacterial agent prepared in Examples 1 to 6 and Comparative Examples 1 to 2 was tested at a mass ratio of 1 wt% to the phosphorus contaminated solution at 25 ° C, 200 rpm / min, pH = 7, and a phosphate concentration of 30 mg / L. The phosphate removal rate was tested 24 hours after repair. The results are shown in Table 1.

[0066]

[0067] It can be seen from Table 1 that the modified sepiolite-iron-reducing bacteria composite bacterial agent obtained in Example 1 of the present invention has the best phosphorus removal effect.

[0068] Figure 1 The X-ray diffraction analysis (XRD) diagram of the modified sepiolite-iron-reducing bacteria composite agent prepared in Example 1 before and after repairing phosphorus-contaminated water bodies, it can be seen that after the repair is completed, from the XRD data, it can be seen that there are obvious Fe3(PO4)2 characteristic peaks at 25.8°, 27.4°, 30.9°, 42.1°, 42.4°, and 48.3°. At the same time, there are obvious Mg(H2PO4)2 and Mg3(PO4)2 characteristic peaks, indicating that the addition of the modified sepiolite-iron-reducing bacteria composite agent can promote the formation of blue iron ore, which is beneficial to the efficient recovery of phosphorus in water bodies.

[0069] Figure 2 This is the X-ray photoelectron spectroscopy (XPS) analysis of the modified sepiolite-iron-reducing bacteria composite agent prepared in Example 1 after repairing phosphorus-contaminated water. It can be seen that Fe 2+ with Fe 3+ The content of iron-reducing bacteria was 1:1, indicating that the iron-reducing bacteria successfully converted Fe 3+ Converted to Fe 2+ , creating favorable conditions for the formation of blue iron ore. Figure 2 a in the formula is Fe 3+The XPS fitting peak corresponds to a binding energy position of 728.24 eV, which is consistent with the Fe 3+ The binding energy position of b is consistent with that of c, accounting for about 4.39% of the total Fe in the modified sepiolite-iron-reducing bacteria composite agent after repairing phosphorus-contaminated water bodies; b is the Fe in blue iron ore 2+ The XPS fitting peak corresponds to a binding energy position of 724.60 eV, which is consistent with the Fe 2+ The binding energy position of is consistent with that of the modified sepiolite-iron-reducing bacteria composite agent after repairing phosphorus-polluted water bodies, accounting for about 32.65% of the total Fe; c is Fe 3+ The XPS fitting peak corresponds to a binding energy position of 724.60 eV, which is consistent with the Fe 3+ The binding energy position of d is consistent with that of d, accounting for about 11.95% of the total Fe in the modified sepiolite-iron-reducing bacteria composite agent after repairing phosphorus-contaminated water bodies; d is attributed to Fe 2+ The XPS fitting peak corresponds to a binding energy position of 710.92 eV, which is consistent with the Fe 2+ The binding energy position of the modified sepiolite-iron-reducing bacteria composite agent after repairing phosphorus-polluted water bodies is consistent, accounting for about 51.02% of the total Fe in the modified sepiolite-iron-reducing bacteria composite agent after repairing phosphorus-polluted water bodies; e is the background curve; f is the Fe 2p XPS curve of the modified sepiolite-iron-reducing bacteria composite agent after repairing phosphorus-polluted water bodies; g is the Fe 2p XPS fitting curve of the modified sepiolite-iron-reducing bacteria composite agent after repairing phosphorus-polluted water bodies. From the above, it can be seen that Fe 2+ with Fe 3+ The content ratio of is about 5:1. The valence state of Fe in the modified sepiolite-iron-reducing bacteria composite agent after repairing phosphorus-contaminated water is mainly Fe 2+ , and mainly exists in the form of blue iron ore.

[0070] In Comparative Example 2, without the introduction of iron-reducing bacteria, the phosphorus removal effect can reach more than 70%, but the adsorbed phosphorus is not blue iron ore with high added value and is difficult to reuse.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A modified sepiolite-iron-reducing bacteria composite agent, characterized in that: It is composed of modified sepiolite and iron-reducing bacteria; The modified sepiolite is composed of iron-magnesium co-hydroxide supported on sepiolite.

2. The modified sepiolite-iron-reducing bacteria composite agent according to claim 1, characterized in that: The total mass of the iron and magnesium elements in the iron-magnesium co-hydroxide is 0.05 to 0.6 times the mass of the sepiolite; The mass ratio of magnesium element to iron element in the iron-magnesium co-hydroxide is (0.1~1):

1.

3. The modified sepiolite-iron-reducing bacteria composite agent according to claim 1, characterized in that: The iron-reducing bacteria is selected from Shewanella oneidensis MR-1.

4. A modified sepiolite-iron-reducing bacteria composite agent according to any one of claims 1 to 3, characterized in that: The cell density of the iron-reducing bacteria is 10 6 ~10 8 cfu / mL.

5. A method for preparing a modified sepiolite-iron-reducing bacteria composite agent according to any one of claims 1 to 4, characterized in that: Adding sepiolite to an aqueous solution containing iron ions and magnesium ions, adjusting the pH to alkaline to perform a hydrolysis precipitation reaction, and after the reaction is completed, filtering, washing, drying and grinding are performed in sequence to obtain a modified sepiolite; The modified sepiolite is sterilized, mixed with iron-reducing bacteria and cultured in a culture medium to obtain the modified sepiolite.

6. The method for preparing a modified sepiolite-iron-reducing bacteria composite agent according to claim 5, characterized in that: The aqueous solution containing iron ions and magnesium ions has a concentration of iron ions of 1.25 to 7.5 g / L and a concentration of magnesium ions of 1.25 to 7.5 g / L; The concentration of the sepiolite added to the aqueous solution containing iron ions and magnesium ions is measured at 10-25 g / L.

7. The method for preparing a modified sepiolite-iron-reducing bacteria composite agent according to claim 5, characterized in that: The conditions of the hydrolysis precipitation reaction are: adjusting the pH to 10-12, stirring the reaction at room temperature for 2-12 hours.

8. The method for preparing a modified sepiolite-iron-reducing bacteria composite agent according to claim 5, characterized in that: The culture medium is LB culture medium; The culture time is 1 to 2 days.

9. The use of a modified sepiolite-iron-reducing bacteria composite agent according to any one of claims 1 to 4, characterized in that: Used for removal and recovery of phosphorus in phosphorus-contaminated water bodies.

10. The use of a modified sepiolite-iron-reducing bacteria composite agent according to claim 9, characterized in that: The dosage of the modified sepiolite-iron-reducing bacteria composite agent in the phosphorus-contaminated water body is 1wt%~5wt%; The inorganic phosphorus concentration in the phosphorus-polluted water body is greater than 0.05 mg / L.

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