Manganese modified basalt fiber carrier suitable for constructed wetland and preparation method and application thereof

Abstract

A kind of manganese modified basalt fiber carrier suitable for artificial wetland and its preparation method and application, steps are as follows: after being cleaned with acetone, basalt fiber bundle is immersed in alkali solution and soaked, after being taken out, repeatedly wash with deionized water, until basalt fiber is neutral, then dry for standby;After being treated, basalt fiber is soaked in H2O2 solution, after being taken out, repeatedly wash with deionized water, then dry for standby;Then put into MnO4 ‑ Solution, and add Mn 2+ Solution containing, place on constant temperature magnetic stirrer and stir, after soaking, wash with deionized water, and dry.The present application is simple in operation, low in cost and green and environment-friendly.The increase of oxygen-containing functional groups on the surface of basalt fiber improves hydrophilicity and biocompatibility, and the attachment of fiber surface aggregates greatly increases roughness, promotes the attachment of microorganisms on its surface, significantly improves the efficiency of sewage treatment, and can be widely used in the field of sewage treatment biofilm carrier modification.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of modification of inorganic fiber material biofilm carrier for sewage treatment, and particularly relates to a manganese modified basalt fiber carrier suitable for constructed wetlands and a preparation method and application thereof. BACKGROUND

[0002] As an ecological treatment technology, constructed wetlands have the advantages of low cost, easy maintenance and good treatment effect, and are widely used in various wastewater treatment. Constructed wetlands are composed of plants, microorganisms and substrates, and each component plays an important role in pollutant purification. The difference in substrate type will lead to different adsorption capacity for pollutants and different microbial adhesion capacity, so the selection of substrate is a key factor in wetland construction. At present, the traditional constructed wetland substrate often has the disadvantages of small specific surface area, weak microbial adhesion and poor removal effect, while the new industrial waste and artificial materials have the problems of possible secondary pollution and high cost. In addition, although the research and development of new substrates has always been one of the research hotspots in the field of wetlands, at present, most of them are limited to the development of phosphorus removal substrates, and few of them are committed to finding new substrates that are conducive to microbial adhesion and biofilm formation. These factors have limited the further popularization and application of constructed wetlands. Therefore, it is necessary to explore a new type of constructed wetland substrate with large specific surface area, strong microbial adhesion, low cost and no secondary pollution, so as to improve the pollutant removal efficiency of constructed wetlands and expand the application of constructed wetlands in the field of wastewater treatment.

[0003] Basalt fiber (BF) mainly contains SiO2, Al2O3, Fe2O3 and CaO, which is a new type of micron-sized fiber material with green environmental protection. It has the advantages of low cost, good chemical stability, corrosion resistance and high specific surface area, which is conducive to the fixation and agglomeration of organic matter, and can be used as a high-performance microbial carrier in the field of water treatment. Therefore, it is theoretically feasible to add basalt fiber as a new type of filler to constructed wetlands. However, due to the smooth surface of BF, it is hydrophobic and electronegative, which will have an adverse effect on microbial adhesion, so it is necessary to treat the surface of BF to enhance the biological affinity of basalt fiber, so as to make it a more excellent biofilm carrier for application in constructed wetlands.

[0004] However, among the current modification methods of basalt fiber, the research is mainly focused on improving its mechanical properties, and there is little research on improving the biological affinity of basalt fiber as a biological carrier, especially there is no related report on the application of manganese in the surface modification of basalt fiber. SUMMARY

[0005] Technical problems: In view of the deficiencies of the prior art, the present application provides a manganese modified basalt fiber carrier suitable for constructed wetlands, a preparation method and application thereof, which introduces manganese oxide onto the surface of basalt fiber through surface coating, increases the oxygen-containing functional groups on the surface of basalt fiber, improves its biological affinity, and at the same time, the agglomerates adhere to the surface of basalt fiber, which increases the specific surface area and roughness of basalt fiber, is beneficial to the adhesion of microorganisms, and meets the requirements of the carrier filler for the application in constructed wetlands.

[0006] Technical scheme: A preparation method of a manganese modified basalt fiber carrier suitable for constructed wetlands, the steps are as follows:

[0007] Step one. Alkali treatment: immerse the basalt fiber bundle cleaned by acetone in an alkali solution, soak at 30-50℃ for 30-90min, then take out and repeatedly rinse with deionized water until the basalt fiber is neutral, and then dry for standby;

[0008] Step two. Activation: immerse the basalt fiber after alkali treatment in H2O2 solution, soak at 80-125℃ for 1-2h, then take out and repeatedly rinse with deionized water, and then dry for standby;

[0009] Step three. Surface coating: put the activated basalt fiber into the MnO4 - solution containing Mn 2+ solution, place it on a constant temperature magnetic stirrer for stirring, rinse it with deionized water after soaking, and then dry it.

[0010] As a preferred, the step one is to soak at 40℃ for 1h.

[0011] As a preferred, the alkali solution in the step one is KOH solution, and the concentration of KOH solution is 1mol / L.

[0012] As a preferred, the mass fraction of H2O2 solution in the step two is 15%, and the soaking is at 90℃ for 1.5h.

[0013] As a preferred, the stoichiometric molar ratio of Mn - and MnO4 2+ in the MnO4 2+ solution containing Mn - and the Mn 2+ solution containing Mn is 3:2, and the chemical equation of the reaction process is 3Mn - +2MnO4 + +2H2O→5MnO2↓+4H .

[0014] As a preferred, the MnO4 - solution containing Mn 2+The solution is a MnSO4 solution, and the concentration of the KMnO4 solution is 0.03 mol / L, and the concentration of the MnSO4 solution is 0.045 mol / L.

[0015] Preferably, the soaking mode in step three is constant temperature magnetic stirrer stirring at 40 DEG C for 8h, and standing for 16h.

[0016] The manganese-modified basalt fiber carrier for artificial wetlands prepared by the method.

[0017] The application of the manganese-modified basalt fiber carrier for artificial wetlands in water treatment.

[0018] The manganese oxide compound has the characteristics of strong oxidizing property and large specific surface area, and can realize the remediation of water pollution through redox, adsorption complexation, and coprecipitation. Coating the manganese oxide compound on the surface of the basalt fiber can increase the specific surface area and surface roughness, increase the number of oxygen-containing functional groups on the surface, and thus promote the adhesion of microorganisms. In addition, manganese is an indispensable element for bacterial growth and participates in redox reactions and promotes the secretion of extracellular polymers. Introducing the manganese oxide into the surface of the carrier is also conducive to reducing the hydrophobicity and negative charge of the carrier, so that the basalt fiber has better hydrophilicity and biocompatibility.

[0019] Beneficial effects: The modification method of the basalt fiber carrier disclosed by the application is simple to operate, low in cost, and green and environmentally friendly. The manganese-modified basalt fiber carrier prepared by the method has the advantages of the basalt fiber itself, that is, corrosion resistance, high temperature resistance, good chemical stability, and high specific surface area. In addition, the introduction of the manganese oxide improves the hydrophilicity and biocompatibility of the surface of the basalt fiber, the increase of the oxygen-containing functional groups on the surface, and the substantial increase of the surface roughness are conducive to the adhesion of microorganisms, and the biomass is significantly improved. In addition, the manganese oxide compound generated by the modification has the characteristics of strong oxidizing property and large specific surface area, and can realize the remediation of water pollution through redox, adsorption complexation, and coprecipitation. The manganese-modified basalt fiber can play a unique role in artificial wetland sewage treatment. The test found that the pollutant removal rate of the manganese-modified basalt fiber filler artificial wetland was obviously better than that of the calcium-modified basalt fiber filler and the wetland system without filling the basalt fiber. Among them, the total nitrogen removal rate is increased by 10% and 20% respectively compared with the calcium-modified and unmodified, the total phosphorus removal rate is increased by 12% and 26% respectively compared with the calcium-modified and unmodified, and the COD removal rate is increased by 10% and 30% respectively compared with the calcium-modified and unmodified, which indicates that the manganese-modified basalt fiber filler has obvious advantages in artificial wetland pollution removal. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 , the scanning electron microscope images of the basalt fiber carrier before and after modification (Mn-BF), wherein (a) is before modification, and (b) is after modification.

[0021] Figure 2 Fig. 2 is a micro-morphology observation diagram of the basalt fiber carrier (Mn-BF) before and after modification after the film is hung, wherein (a) is before modification, and (b) is after modification.

[0022] Figure 3 Fig. 3 is a real object diagram of the basalt fiber carrier (Mn-BF) before and after modification after the film is hung, wherein (a) is before modification, and (b) is after modification.

[0023] Figure 4 Fig. 4 is a comparison of the extracellular polymer EPS secretion amount of the modified basalt fiber (Mn-BF) and the unmodified basalt fiber (BF).

[0024] Figure 5 Fig. 5 is a comparison of the water purification effect of the modified basalt fiber (Mn-BF) and the unmodified basalt fiber (BF) as the biological carrier filler, wherein (a) is the TN removal rate, (b) is the TP removal rate, and (c) is the COD removal rate.

[0025] Figure 6 Fig. 6 is a comparison of the water purification effect of the modified basalt fiber (Mn-BF) as the biological carrier filler applied in the constructed wetland system, wherein (a) is the TN removal rate, (b) is the TP removal rate, and (c) is the COD removal rate. (a, b, c on the column chart represent the significance level)

[0026] Figure 7 Fig. 7 is a comparison and analysis of the water purification effect of the modified basalt fiber (Mn-BF) as the biological carrier filler applied in the constructed wetland system and the existing modified fiber (Ca-BF). (a, b, c on the column chart represent the significance level) DETAILED DESCRIPTION

[0027] The application will be further described below in combination with the drawings and specific examples.

[0028] The basalt fiber used in the examples of the specification of the application is purchased from the untwisted roving product of Jiangsu Lvxin New Material Technology Co., Ltd., which is composed of multiple parallel filaments or a single parallel filament in the untwisted state, and the model number is CBF13-1200.

[0029] Example 1

[0030] The preparation method of the manganese modified basalt fiber carrier suitable for the constructed wetland in the embodiment is as follows:

[0031] (1) 100 g of basalt fiber is weighed and placed in 500 ml of acetone for ultrasonic cleaning for 2 h to remove the surface wetting agent, and then taken out, cleaned with deionized water, and dried in an oven at 105℃ for 4 h;

[0032] (2) The basalt fiber in step (1) was immersed in 1M KOH (40°C, 1h) solution for alkaline etching to increase its surface contact area, followed by repeated washing with deionized water to neutral, oven dried at 105°C for 4h;

[0033] (3) The basalt fiber in step (2) was immersed in H2O2 (15%) solution at constant temperature 90°C for 1.5h for activation treatment to produce active silanol groups (Si-OH), followed by washing with deionized water, oven dried at 105°C for 4h;

[0034] (4) The activated basalt fiber was immersed in 0.03M KMnO4 solution, followed by adding 0.045M MnSO4 solution, placed on constant temperature magnetic stirrer for stirring, washed with deionized water after immersion, and dried. The manganese modified basalt fiber carrier MBF-1 (Mn-BF) was prepared.

[0035] Example 2

[0036] The same as example 1, except that the basalt fiber in step (1) was immersed in 1M KOH (30°C, 90min) solution for alkaline etching to increase its surface contact area in step (2);

[0037] The basalt fiber in step (2) was immersed in H2O2 (15%) solution at constant temperature 80°C for 2h for activation treatment in step (3). The manganese modified basalt fiber carrier MBF-2 was prepared.

[0038] Example 3

[0039] The same as example 1, except that the basalt fiber in step (1) was immersed in 1M KOH (50°C, 30min) solution for alkaline etching to increase its surface contact area in step (2);

[0040] The basalt fiber in step (2) was immersed in H2O2 (15%) solution at constant temperature 125°C for 1h for activation treatment in step (3). The manganese modified basalt fiber carrier MBF-3 was prepared.

[0041] Evaluation of modification effect:

[0042] The unmodified and modified basalt fiber bundles were cut into fiber segments with a length of 120±5 mm and a controlled mass of 20±0.1 g, and were made into umbrellas, which were placed in a contact oxidation reaction device (5 L) for biofilm experiment. The reaction device was a cylinder with an inner diameter of 150 mm and a height of 250 mm, and the device material was organic glass. A fixing device was provided at the top of each reactor to suspend the fiber carrier, and an aeration disc was provided at the bottom to supply oxygen. The influent was artificial water, with sodium acetate as the carbon source, ammonium sulfate and potassium nitrate as the nitrogen source, and potassium dihydrogen phosphate as the phosphorus source, wherein the COD:N:P was 100:5:1. The sludge was inoculated from a sewage treatment plant in Nanjing (MLSS=5200±50 mg / L), and the biofilm rate and residual biofilm rate were determined after continuous aeration for 72 h. After successful biofilm formation, the basalt fiber surface micro-morphology was observed, and the water quality treatment evaluation was carried out to record the pollutant removal effect. At the same time, the basalt fiber filler after successful biofilm formation was added to the artificial wetland system, and the pollutant removal effect was recorded to explore its applicability in the artificial wetland system.

[0043] 1) Biofilm rate: the basalt fiber carrier was taken out and dried for measurement.

[0044]

[0045] wherein: W0(g) is the original weight of the basalt fiber before biofilm formation, and W1(g) is the mass of the basalt fiber and biofilm after a period of time.

[0046] 2) Residual biofilm rate: the basalt fiber carrier was taken out and immersed in a standard PBS buffer, and after 20 min of ultrasonic oscillation at room temperature, it was washed with distilled water and dried to constant weight.

[0047]

[0048] wherein: W2(g) is the mass of the basalt fiber and biofilm after ultrasonic oscillation.

[0049] Further, the standard PBS buffer in 2) is sodium phosphate 0.4 g / L, sodium chloride 8.5 g / L, and sodium phosphate dibasic 2.2 g / L, pH=7.

[0050] Experimental results:

[0051] 1. Modified scanning electron microscope (SEM) analysis:

[0052] As Figure 1As shown, the basalt fiber carrier surface before modification is smooth and almost free of impurities. After manganese modification, some obvious agglomerates can be seen on the surface of the basalt fiber carrier, indicating that manganese oxide has been successfully coated on the surface of the basalt fiber. The surface morphology of the modified basalt fiber has been obviously changed, and the surface roughness has been improved, which is beneficial to the attachment of microorganisms and thus improves the effect of wastewater treatment.

[0053] 2. Analysis of biofilm formation performance

[0054] 1) Analysis of biofilm formation rate and residual biofilm formation rate

[0055] Table 1. Comparison of biofilm formation effect of basalt fiber carriers before and after modification

[0056]

[0057] 2) Analysis of microbial diversity after biofilm formation

[0058] Table 2. Comparison of microbial diversity of basalt fiber carriers before and after modification

[0059]

[0060] Alpha diversity refers to the indicators of species in local uniform habitats in terms of richness, diversity and uniformity, also known as intra-habitat diversity. In this application, Chao1 and Observed species are used to describe richness, and Shannon and Simpson indices are used to describe diversity. The coverage of each group is close to 100%, indicating that the sequencing results of the samples can represent the true situation of the bacterial flora of each reactor. The Observed species and Chao1 indices are Mn-BF > BF, indicating that Mn-BF has more microbial species and a more abundant community composition. According to the Shannon and Simpson index values, the microbial diversity of Mn-MBF is higher than that of the unmodified BF group, because the increase in surface roughness causes physical changes that increase the adsorption of microorganisms, and there are more types of microorganisms.

[0061] 3) Analysis of micro-morphology observation (SEM) after biofilm formation:

[0062] As Figure 2 , Figure 3As shown in the figure, the unmodified basalt fiber surface is smooth, and no activated sludge is attached. The surface of the manganese-modified basalt fiber is wrapped by a large amount of biomass, and the existing gaps, pores and channels are conducive to the transmission of nutrients, promoting mass transfer effect, thereby facilitating the growth and reproduction of microorganisms inside. At the same time, the attachment of biomass provides better adsorption capacity and stable internal environment for basalt fiber, allowing microorganisms to grow continuously at high density in a stable mixed microbial community. The results show that the use of manganese-modified basalt fiber is conducive to the attachment and growth of microorganisms, and increases the amount of microorganism attachment. Therefore, the manganese-modified basalt fiber carrier has excellent bio-attachment performance, is green and environmentally friendly, and can be widely used as a biological carrier filler in the field of water treatment.

[0063] 4) Evaluation of the activated sludge fixing performance of modified basalt fiber

[0064] After culturing the modified basalt fiber and the unmodified basalt fiber in the sequencing batch activated sludge reactor for 20 days, the total amount of EPS on the fiber surface and the content of each component were determined. As shown in the figure, Figure 4 the total amount of EPS of the manganese-modified basalt fiber is twice that of the unmodified fiber, and the PS / PN ratio of the manganese-modified fiber is significantly higher than that of the unmodified fiber. Extracellular polymer EPS is conducive to the coagulation and fixation of microorganisms on the carrier surface, and the modified EPS has been significantly increased. PN protein and PS polysaccharide are two important components of EPS, and the amount of PS and PN of the manganese-modified fiber is higher than that of the unmodified basalt fiber. PN is an important substance for activated sludge granulation and structure stability, and PS with a highly branched structure is conducive to the absorption and bridging of biomass. The increase of PN / PS is an indicator of improving the aggregation performance. It can be seen that the content of PN and PS is increased after manganese modification, the PN / PS value is increased, and the stability of the structure of the biological carrier is improved.

[0065] 3. Evaluation of the wastewater treatment efficiency of modified basalt fiber filler:

[0066] The modified basalt fiber and the unmodified basalt fiber were filled into the contact oxidation reaction device, and the wastewater treatment effect of the filler was evaluated by comparison after running for 60 days. The change of pollutant removal rate in the contact oxidation stage is shown in the figure Figure 5 . Among them, the average removal rate of total nitrogen of the manganese-modified fiber is increased by 16% compared with the unmodified fiber, the average removal rate of total phosphorus is increased by 20%, and the average removal rate of COD is increased by 16%.

[0067] Manganese modified basalt fiber is filled into the constructed wetland system, and the system is operated for 3 months to evaluate the applicability of the manganese modified basalt fiber in the constructed wetland. At the same time, a group of devices filled with calcium modified basalt fiber (modification method referring to the invention patent CN 115057526 A) is also set up during the experiment to evaluate the advantages of manganese modification. The removal rate changes of the pollutants in the constructed wetland are as shown in Figure 6 The removal rates of total nitrogen, total phosphorus and COD in the wetland system filled with manganese modified fiber are obviously higher than those of the control group without manganese modified fiber. The comparative analysis of the pollutant removal rates of manganese modification and calcium modification is as shown in Figure 7 During the 3-month operation of the constructed wetland system, the average removal rate of total nitrogen in the manganese modified wetland group is 89.34%, while that in the calcium modified experimental group is 79.18%; the average removal rate of total phosphorus in the manganese modified wetland group is 76.81%, while that in the calcium modified group is 64.05%; and the average removal rate of COD in the manganese modified wetland group is 72.16%, while that in the calcium modified group is 62.53%. It is shown that the difference in modification methods leads to different pollutant removal rates of the wetland system, and the manganese modified basalt fiber greatly improves the pollutant removal effect of the wetland system, and has obvious advantages in the applicability to the wetland system.

[0068] The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation made by using the present application specification, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for the preparation of a manganese-modified basalt fiber carrier suitable for use in a constructed wetland, characterized in that, The steps are as follows: Step one. Alkali treatment: after the basalt fiber bundle is cleaned by acetone, it is immersed in an alkali solution, soaked at 40°C for 1 h, and then taken out and repeatedly washed with deionized water until the basalt fiber is neutral, and then dried for standby; Step two. Activation: after the alkali treated basalt fiber is soaked in H2O2 solution, it is soaked at 90°C for 1-2 h, taken out and repeatedly washed with deionized water, and then dried for standby; Step three. Surface coating: The activated basalt fiber was put into the solution containing MnO4 - solution, and was placed on a constant temperature magnetic stirrer for stirring. After soaking, it was cleaned with deionized water and was dried. 2+ solution, and was placed on a constant temperature magnetic stirrer for stirring. After soaking, it was cleaned with deionized water and was dried.

2. A method for preparing a manganese-modified basalt fiber carrier for use in a constructed wetland according to claim 1, characterized in that, The alkali solution in step one is KOH solution, and the concentration of KOH solution is 1 mol / L.

3. A method of preparing a manganese-modified basalt fiber carrier for use in a constructed wetland according to claim 1, characterized in that, MnO4 - solution and Mn 2+ Mn in solution 2+ and MnO4 - stoichiometric molar ratio of 3:

2.

4. A method of preparing a manganese-modified basalt fiber carrier for use in a constructed wetland according to claim 3, characterized in that, The solution containing MnO4 - The solution containing MnO4 2+ The solution containing MnO4 5. The method of claim 1, wherein the manganese-modified basalt fiber carrier for a constructed wetland is characterized by, The soaking mode in step three is constant temperature magnetic stirrer stirring at 40°C for 8 h, and standing for 16 h.

6. The manganese modified basalt fiber carrier suitable for artificial wetlands prepared based on the method of any one of claims 1-5.

7. The application of the manganese modified basalt fiber carrier suitable for artificial wetlands based on claim 6 in water treatment.

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