Composition for deeply removing trivalent arsenic in wastewater from iron-based mineral aggregate and application of composition

Abstract

The invention discloses a composition for deeply removing trivalent arsenic in wastewater from an iron-based mineral aggregate and application of the composition. The composition comprises an iron-oxidizing bacteria solution and an iron-based mineral aggregate, the iron-based mineral aggregate comprises red mud and pyrite, and the mass ratio of the red mud to the pyrite is 1: (0.9-1.1). When the composition is used for deeply removing trivalent arsenic in wastewater, the process comprises the following steps: culturing iron-oxidizing bacteria to a logarithmic phase, centrifuging, washing and resuspending to obtain an iron-oxidizing bacteria solution; the method comprises the following steps: adding a composition containing an iron-oxidizing bacteria solution and an iron-based mineral aggregate into wastewater containing trivalent arsenic to carry out arsenic removal reaction, and separating after the reaction is finished. According to the composition, the synergistic effect of all the components is utilized, the oxidation-adsorption-precipitation process of trivalent arsenic in wastewater is achieved through a one-step method, no strong oxidizing agent needs to be added for pre-oxidation treatment, especially when the arsenic concentration in the wastewater is 20-200 mg / L, the excellent removal effect is achieved, and the trivalent arsenic removal efficiency can reach 90%.

Description

Technical Field

[0001] The invention relates to a dearsenicizing composition, in particular to a composition for deeply removing trivalent arsenic from wastewater using an iron-based mineral material and application thereof, belonging to the technical field of industrial wastewater treatment. Background Art

[0002] Arsenic-containing wastewater generated by mining and mineral processing industries poses a serious threat to human life. Arsenic mainly exists in the form of arsenic (III) and arsenic (V). The toxicity of arsenic (III) is about 60 times that of arsenic (V). Compared with arsenic (V), arsenic (III) interacts less strongly with most solid surfaces, and arsenic (III) removal is more difficult than arsenic (V). At present, arsenic water purification technologies mainly include flocculation precipitation, adsorption, membrane separation and ion exchange. However, most of these technologies cannot efficiently remove arsenic (III), and generally arsenic (III) needs to be oxidized and pretreated to convert it into arsenic (V). Since O2 in the air has a poor oxidation effect on arsenic (III), some strong oxidants, such as ozone, hypochlorite, potassium permanganate and hydrogen peroxide, are used to oxidize arsenic (III). However, these strong oxidants are expensive and may cause residual reagents in water and form oxidation by-products. Therefore, it is urgent to explore green, efficient and low-cost As (III) removal technologies.

[0003] Red mud is a highly alkaline waste generated during the production of alumina. The amount of red mud produced for every ton of alumina produced is about 1.0~1.5 tons. Red mud is highly alkaline, has a high salt content, and has a high risk of pollutant migration. Pyrite is also a mining waste. Pyrite is easily oxidized by exposure to water, air and microbial environments, producing acidic wastewater containing high concentrations of metal ions and sulfates. It poses a major threat to water and soil, thereby threatening the safety of humans and other organisms. Therefore, how to rationally utilize red mud and pyrite has become one of the urgent tasks facing the mining and metallurgical industry.

[0004] In recent years, many researchers have focused on red mud and pyrite to remediate arsenic-contaminated water bodies. Red mud can not only adsorb arsenic by forming inner layer complexes between iron minerals and arsenic, but also fix arsenic through ligand exchange and iron-arsenic co-precipitation. The sulfide ions produced by the dissolution of pyrite can form arsenic sulfide with low solubility with arsenic to achieve the purpose of removing arsenic from water. However, these existing methods are not effective for the removal of arsenic (III). Therefore, it is necessary to explore a new method for efficiently treating arsenic (III) in acidic water using red mud and pyrite. However, there are few reports on the use of iron-oxidizing bacteria to promote the synergistic treatment of acidic arsenic (III) wastewater with red mud and pyrite. Summary of the invention

[0005] In view of the problems existing in the prior art, the first object of the present invention is to provide a composition for deeply removing trivalent arsenic from wastewater by using iron-based mineral materials. The composition uses red mud and pyrite, which are mining and smelting solid wastes, as raw materials, combined with iron oxidizing bacteria, and utilizes the synergistic effect of the various components to achieve the oxidation-adsorption-precipitation process of trivalent arsenic in wastewater in one step, without adding any strong oxidants for pre-oxidation treatment of trivalent arsenic. The composition consumes a large amount of mining and smelting solid wastes. In the process of realizing the deep treatment of arsenic-containing wastewater, the resource utilization of red mud is also realized, thereby achieving the technical purpose of treating waste with waste.

[0006] The second object of the present invention is to provide an application of a composition for deeply removing trivalent arsenic from wastewater using an iron-based ore, which is used to deeply remove trivalent arsenic from wastewater. The above composition is used to deeply remove trivalent arsenic from wastewater, especially when the arsenic concentration in arsenic-containing wastewater is 20-200 mg / L, and has excellent technical effects. After testing, the total arsenic removal efficiency of the composition provided by the present invention can reach 90%, and the arsenic in the obtained precipitation product is mainly present as pentavalent arsenic, avoiding subsequent secondary pollution.

[0007] In order to achieve the above technical objectives, the present invention provides a composition for deeply removing trivalent arsenic from wastewater with an iron-based mineral material, the composition comprising an iron-oxidizing bacterial liquid and an iron-based mineral material; the iron-based mineral material comprises red mud and pyrite, and the mass ratio of red mud to pyrite is 1:0.9~1.1.

[0008] The composition provided by the present invention can realize the oxidation-adsorption-precipitation process of trivalent arsenic in wastewater in one step, wherein iron oxidizing bacteria significantly promote the oxidation and dissolution of pyrite in the system, the renewal of the surface of pyrite promotes the formation of hydroxyl radicals in the solution, and the hydroxyl radicals, as a strong oxidant, oxidize arsenic (III) in the solution into arsenic (V), and arsenic (V) is more easily adsorbed and removed than arsenic (III); the bases in the red mud react with the hydrogen ions in the arsenic-containing wastewater, the agglomerated red mud particles become dispersed, the specific surface area of ​​the red mud increases, and it is more conducive to the adsorption of arsenic in the water; in addition, due to the addition of iron oxidizing bacteria, iron (II) will be oxidized into iron (III), and the red mud increases the pH of the wastewater, thereby causing the iron (III) in the water to be hydrolyzed and precipitated, and the hydrolysis product uses the red mud particles as growth sites, thereby further adsorbing the arsenic in the water.

[0009] As a preferred embodiment, the iron-oxidizing bacteria are moderately thermophilic iron-oxidizing bacteria and / or Leptospira ferrooxidans.

[0010] As a preferred solution, the bacterial concentration of the iron oxidizing bacterial solution is 3-7×10 9 Pieces / mL.

[0011] As a preferred solution, the volume mass ratio of the iron oxidizing bacteria liquid to the iron-based mineral material is 5-15 ml: 3-6 g.

[0012] The present invention also provides an application of the composition for deeply removing trivalent arsenic from wastewater using an iron-based mineral material, which is used for deeply removing trivalent arsenic from wastewater.

[0013] As a preferred scheme, the process of deeply removing trivalent arsenic from wastewater comprises: culturing iron-oxidizing bacteria to the logarithmic phase, centrifuging, washing and resuspending to obtain an iron-oxidizing bacterial liquid; adding a composition including the iron-oxidizing bacterial liquid and an iron-based mineral to wastewater containing trivalent arsenic to carry out an arsenic removal reaction, and separating after the reaction is completed.

[0014] As a preferred solution, the concentration of trivalent arsenic in the wastewater is 20-200 mg / L.

[0015] As a preferred solution, the particle size of pyrite in the iron-based ore is 38-74 μm.

[0016] As a preferred solution, the iron oxidizing bacteria culture process adopts 9K culture medium with a pH of 1.9-2.1.

[0017] As a preferred solution, the amount of the iron oxidizing bacteria liquid added to the wastewater is 0.5-1.5%.

[0018] As a preferred solution, the amount of the iron-based mineral added to the wastewater is 2-6 g / L.

[0019] As a preferred solution, the arsenic removal reaction process is: reacting at 25-35°C and a rotation speed of 150-200 r / min for 10-15 days.

[0020] As a preferred solution, the pH of the arsenic removal reaction is 3.9-4.1.

[0021] Compared with the prior art, the beneficial technical effects of the technical solution of the present invention are:

[0022] 1) The composition provided by the present invention uses red mud and pyrite, which are mining solid wastes, as raw materials, combined with iron oxidizing bacteria, and utilizes the synergistic effect of the three to achieve the oxidation-adsorption-precipitation process of trivalent arsenic in wastewater in one step, without adding any strong oxidants to pre-oxidize the trivalent arsenic. In addition, the composition consumes a large amount of mining solid waste. In the process of realizing the in-depth treatment of arsenic-containing wastewater, the resource utilization of red mud is also realized, thereby achieving the technical purpose of treating waste with waste.

[0023] 2) In the technical solution provided by the present invention, the above-mentioned composition is used to deeply remove trivalent arsenic in wastewater, especially when the arsenic concentration in the arsenic-containing wastewater is 20~200 mg / L, and it has excellent technical effects. According to detection, the total arsenic removal efficiency of the composition provided by the present invention can reach 90%, and the arsenic in the obtained precipitation product mainly exists in the form of pentavalent arsenic, avoiding subsequent secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The scanning electron microscope-energy spectrum (SEM-EDS) images of the red mud and pyrite used in the specific examples;

[0025] in, Figure 1 (a) is an electron microscope image of pyrite used in a specific embodiment, Figure 1 (b) is an electron microscope image of the red mud used in the specific embodiment, Figure 1 (c) is the energy spectrum of pyrite used in the specific embodiment, Figure 1 (d) is an energy spectrum diagram of the red mud used in the specific example;

[0026] Figure 2 is the X-ray diffraction (XRD) pattern of red mud and pyrite used in the specific examples;

[0027] in, Figure 2 (a) is an X-ray diffraction pattern of pyrite used in a specific embodiment, Figure 2 (b) is an X-ray diffraction pattern of the red mud used in the specific example;

[0028] Figure 3 The curves of the total arsenic, arsenic (III) ratio, pH, oxidation-reduction potential (ORP), total iron and iron (II) in the solution in Example 1 are shown;

[0029] in, Figure 3 (a) is a curve showing the change of total arsenic in the solution used in specific embodiment 1, Figure 3 (b) is a curve showing the change in the proportion of arsenic (III) in the solution used in Specific Example 1, Figure 3 (c) is the solution pH change curve used in specific embodiment 1, Figure 3 (d) is the solution oxidation-reduction potential change curve used in specific embodiment 1, Figure 3 (e) is the total iron change curve in the solution used in specific embodiment 1, Figure 3 (f) is the curve of change of iron (II) in the solution used in specific example 1;

[0030] Figure 4 The electron paramagnetic resonance detection result of the hydroxyl radical in Example 1;

[0031] Figure 5The X-ray photoelectron spectroscopy (XPS) results of the mixed minerals before and after the reaction in Example 1;

[0032] in, Figure 5 (a) is the X-ray photoelectron spectroscopy result of Fe 2p before and after the reaction of the mixed mineral in specific embodiment 1, Figure 5 (b) is the X-ray photoelectron spectroscopy result of S 2p before and after the reaction of the mixed minerals in specific example 1, Figure 5 (c) is the X-ray photoelectron spectroscopy result of Al 2p before and after the reaction of the mixed mineral in specific example 1, Figure 5 (d) is the X-ray photoelectron spectroscopy result of As3d before and after the reaction of the mixed mineral in specific example 1;

[0033] Figure 6 The transmission electron microscope (TEM) images of the red mud particles in the mixed minerals in Example 1 before and after the reaction;

[0034] in, Figure 6 (a) is a transmission electron microscope image of red mud particles in the mixed minerals in specific example 1 before reaction. Figure 6 (b) and 6 (c) are transmission electron microscope images of red mud particles in the mixed minerals after reaction in specific example 1. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of the present invention, the present invention will be described in more comprehensive and detailed manner in conjunction with the accompanying drawings and preferred embodiments of the specification. It should be noted that the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1

[0037] This embodiment provides a composition for deeply removing trivalent arsenic from wastewater with an iron-based ore, and the composition is used to deeply remove trivalent arsenic from wastewater, and the specific process is as follows:

[0038] (1) Iron-oxidizing bacteria were cultured aerobically in 9K medium at 30°C and 170 r / min. The medium composition was (NH4)2SO4 3.0 g / L, K2HPO4·3H2O 0.5 g / L, MgSO4·7H2O 0.5 g / L, KCl 0.1 g / L, Ca(NO3)2 0.01 g / L, and FeSO4·7H2O 44.7 g / L. The initial pH of the medium was adjusted to 2.0 with 0.1 mol / L dilute sulfuric acid.

[0039] (2) Remove metabolites by filtering with filter paper, and then centrifuge at 10,000 r / min and 4°C for 15 minutes to obtain a cell pellet; wash the original cell pellet with sterile iron-free 9K medium (pH = 2) and re-centrifuge for 3 times; then dilute the cell pellet with sterile iron-free 9K medium (pH = 2) to obtain a concentrated bacterial solution without metabolites;

[0040] (3) After crushing the pyrite, the mineral particles with a particle size range of 38-74 μm were collected by wet sieving, rinsed with deionized water three times, and placed in a vacuum drying oven (35°C, 0.001 Pa) for 24 h for later use;

[0041] (4) The arsenic (III) fixation test with pyrite and red mud was carried out in a 250 mL glass conical flask, with 99 mL of 9K basal salt medium and 1 mL of concentrated bacteria added; the initial pH of the bacterial solution was adjusted to pH = 2.00 ± 0.05 with 0.1 mol / L dilute sulfuric acid, and then 2 g of solid sample (pyrite / red mud) was added to the conical flask, the mass ratio of pyrite to red mud was set to 1:1, and sodium arsenite was added to make the initial arsenic (III) concentration 200 mg / L. The conical flask was placed in a shaker at a temperature of 30°C and a speed of 170 r / min for 15 days;

[0042] (5) During the test, 300 μL of liquid samples were collected every 2 days and filtered through a 0.45 μm pore size filter membrane. The total arsenic, arsenic (III), total iron, iron (II), pH value and redox potential in the solution were measured. Figure 3 shown.

[0043] Depend on Figure 3 It can be seen that the total arsenic removal efficiency in the experiment reached 88.26%, and arsenic (III) was mainly oxidized to arsenic (V). Within 0 to 15 days, part of the pyrite was oxidized and dissolved under the action of oxygen and iron-oxidizing bacteria, and the dissolved iron (II) was oxidized to iron (III) by iron-oxidizing bacteria; Figure 4 As shown in Figure 2, the renewal catalysis of the pyrite surface produces more hydroxyl radicals to oxidize arsenic (III) to arsenic (V). As the reaction proceeds, the agglomerated red mud particles gradually disperse and the specific surface area increases, which is conducive to the fixation of arsenic. In addition, as shown in Figure 2 Figure 3 As shown in (c), the presence of red mud raises the solution pH to about 4.0, causing iron (III) to precipitate; Figure 5 As shown in the figure, within 0 to 2 days, the aluminum-oxygen bonds and iron-oxygen bonds on the surface of red mud particles are mainly involved in the adsorption of arsenic. Afterwards, the hydrolysis products of iron (III) form a shell structure on the surface of the red mud particles with the red mud particles as the growth site, and co-precipitate with arsenic (III) and arsenic (V) in the solution, thereby achieving efficient synergistic fixation of arsenic (III) in the solution.

[0044] Example 2

[0045] This example is exactly the same as Example 1, except that the arsenic (III) fixation test with pyrite and red mud was carried out in a 250 mL glass conical flask, and 99 mL of 9K basal salt medium and 1 mL of concentrated bacteria were added. The initial pH of the bacterial solution was adjusted to pH = 2.00 ± 0.05 with 0.1 mol / L of dilute sulfuric acid. Then 2 g of solid sample (pyrite / red mud) was added to the conical flask. The mass ratio of pyrite to red mud was set to 1:1. Sodium arsenite was added to make the initial arsenic (III) concentration 100 mg / L. The conical flask was placed in a shaking incubator at a temperature of 30 ° C and a rotation speed of 170 r / min for 15 days.

[0046] After testing, for wastewater with a pH of 2.0 and an arsenic (III) concentration of 100 mg / L, the total arsenic removal efficiency of the composition provided in this embodiment is 87.50%.

[0047] Example 3

[0048] This example is exactly the same as Example 1, except that the arsenic (III) fixation test with pyrite and red mud was carried out in a 250 mL glass conical flask, and 99 mL of 9K basal salt medium and 1 mL of concentrated bacteria were added. The initial pH of the bacterial solution was adjusted to pH = 2.00 ± 0.05 with 0.1 mol / L of dilute sulfuric acid. Then 2 g of solid sample (pyrite / red mud) was added to the conical flask. The mass ratio of pyrite to red mud was set to 1:1. Sodium arsenite was added to make the initial arsenic (III) concentration 50 mg / L. The conical flask was placed in a shaking incubator at a temperature of 30 ° C and a speed of 170 r / min for 15 days.

[0049] After testing, for wastewater with a pH of 2.0 and an arsenic (III) concentration of 50 mg / L, the total arsenic removal efficiency of the composition provided in this embodiment is 87.12%.

[0050] Example 4

[0051] This example is exactly the same as Example 1, except that the arsenic (III) fixation test with pyrite and red mud was carried out in a 250 mL glass conical flask, and 99 mL of 9K basal salt medium and 1 mL of concentrated bacteria were added. The initial pH of the bacterial solution was adjusted to pH = 2.00 ± 0.05 with 0.1 mol / L of dilute sulfuric acid. Then 2 g of solid sample (pyrite / red mud) was added to the conical flask. The mass ratio of pyrite to red mud was set to 1:1. Sodium arsenite was added to make the initial arsenic (III) concentration 25 mg / L. The conical flask was placed in a shaking incubator at a temperature of 30 ° C and a rotation speed of 170 r / min for 15 days.

[0052] After testing, for wastewater with a pH of 2.0 and an arsenic (III) concentration of 25 mg / L, the total arsenic removal efficiency of the composition provided in this embodiment is 82.77%.

[0053] Comparative Example 1

[0054] This comparative example is exactly the same as Example 1, except that no iron oxidizing bacteria are added.

[0055] After testing, for wastewater with a pH of 2.0 and an arsenic (III) concentration of 200 mg / L, the total arsenic removal efficiency of the composition provided in this embodiment is 67.58%.

[0056] Comparative Example 2

[0057] This comparative example is exactly the same as Example 2, except that no iron oxidizing bacteria are added.

[0058] After testing, for wastewater with a pH of 2.0 and an arsenic (III) concentration of 100 mg / L, the total arsenic removal efficiency of the composition provided in this embodiment is 56.23%.

[0059] Comparative Example 3

[0060] This comparative example is exactly the same as Example 3, except that no iron oxidizing bacteria are added.

[0061] It was tested that for wastewater with a pH of 2.0 and an arsenic (III) concentration of 50 mg / L, the total arsenic removal efficiency of the composition provided in this comparative example was 70.50%.

[0062] Comparative Example 4

[0063] This comparative example is exactly the same as Example 4, except that no iron oxidizing bacteria are added.

[0064] It was tested that for wastewater with a pH of 2.0 and an arsenic (III) concentration of 25 mg / L, the total arsenic removal efficiency of the composition provided in this comparative example was 60.55%.

[0065] Comparative Example 5

[0066] This comparative example is exactly the same as Example 1, except that pyrite and iron oxidizing bacteria are not added.

[0067] It was tested that for wastewater with a pH of 2.0 and an arsenic (III) concentration of 200 mg / L, the total arsenic removal efficiency of the composition provided in this comparative example was 28.08%.

[0068] Comparative Example 6

[0069] This comparative example is exactly the same as Example 1, except that no pyrite is added.

[0070] After testing, for wastewater with a pH of 2.0 and an arsenic (III) concentration of 200 mg / L, the total arsenic removal efficiency of the composition provided in this comparative example is 1.63%.

[0071] Comparative Example 7

[0072] This comparative example is exactly the same as Example 1, except that no red mud and iron oxidizing bacteria are added.

[0073] It was tested that for wastewater with a pH of 2.0 and an arsenic (III) concentration of 200 mg / L, the total arsenic removal efficiency of the composition provided in this comparative example was 48.748%.

[0074] Comparative Example 8

[0075] This comparative example is exactly the same as Example 1, except that no red mud is added.

[0076] It was tested that for wastewater with a pH of 2.0 and an arsenic (III) concentration of 200 mg / L, the total arsenic removal efficiency of the composition provided in this comparative example was 2.25%.

Claims

1. A composition for deeply removing trivalent arsenic from wastewater using an iron-based ore, characterized in that: The composition comprises an iron-oxidizing bacterial liquid and an iron-based mineral material; the iron-based mineral material comprises red mud and pyrite, and the mass ratio of the red mud to the pyrite is 1:0.9-1.

1.

2. The composition for deeply removing trivalent arsenic from wastewater using an iron-based ore according to claim 1, characterized in that: The iron oxidizing bacteria are moderately thermophilic iron oxidizing bacteria and / or ferrooxidan Leptospirillum.

3. The composition for deeply removing trivalent arsenic from wastewater using an iron-based ore according to claim 1, characterized in that: The bacterial concentration of the iron oxidizing bacterial solution is 3~7×10 9 / mL; the volume mass ratio of the iron oxidizing bacteria liquid to the iron-based mineral material is 5~15ml:3~6g.

4. An application of a composition for deep removal of trivalent arsenic from wastewater using an iron-based ore, characterized in that: Used for deep removal of trivalent arsenic from wastewater.

5. The use of a composition for deep removal of trivalent arsenic from wastewater using an iron-based ore according to claim 4, characterized in that: The process of deeply removing trivalent arsenic from wastewater comprises: culturing iron-oxidizing bacteria to a logarithmic phase, centrifuging, washing and resuspending to obtain an iron-oxidizing bacterial solution; adding a composition including the iron-oxidizing bacterial solution and an iron-based mineral material to wastewater containing trivalent arsenic to perform an arsenic removal reaction, and separating the solution after the reaction is completed.

6. The use of a composition for deep removal of trivalent arsenic from wastewater using an iron-based ore according to claim 5, characterized in that: The concentration of trivalent arsenic in the wastewater is 20-200 mg / L; the particle size of pyrite in the iron-based ore is 38-74 μm.

7. The use of a composition for deep removal of trivalent arsenic from wastewater using an iron-based ore according to claim 5, characterized in that: The iron oxidizing bacteria culture process adopts 9K culture medium, and its pH is 1.9-2.

1.

8. The use of a composition for deep removal of trivalent arsenic from wastewater using an iron-based ore according to claim 5, characterized in that: The amount of the iron oxidizing bacteria liquid added to the wastewater is 0.5-1.5%; the amount of the iron-based mineral material added to the wastewater is 2-6 g / L.

9. The use of a composition for deep removal of trivalent arsenic from wastewater using an iron-based ore according to claim 5, characterized in that: The arsenic removal reaction process is: reacting at 25-35° C. and a rotation speed of 150-200 r / min for 10-15 days.

10. The use of the composition for deep removal of trivalent arsenic from wastewater using an iron-based ore according to claim 5, characterized in that: The pH of the arsenic removal reaction is 3.9-4.1.

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