Embedded iron-sulfur-based modified biological carrier filler as well as preparation method and application thereof

Abstract

The invention provides embedded iron-sulfur-based modified biological carrier filler as well as a preparation method and application thereof, and the preparation method comprises the following steps: mixing iron-sulfur-based powder with plastic particles to obtain a mixture; the iron-sulfur-based powder comprises an iron element and / or a sulfur element; and carrying out injection molding on the mixture to obtain the embedded iron-sulfur modified biological filler. Wherein the mixing mass ratio of the iron-sulfur-based powder to the plastic particles is 1: (10-100). The method is simple in preparation process, the embedded iron-sulfur-based modified biological filler with uniform size can be obtained, and the method is suitable for industrial batch production; the investment cost is low and the recovery is convenient. After being applied to an activated sludge process, the strain can be rapidly cultured to obtain a biological membrane (gt; 30 days), the microbial denitrification effect can be enhanced, the addition of a carbon source is reduced, a large amount of cost is saved, and the method has a great industrial application prospect.

Description

Technical Field

[0001] The present invention relates to the field of sewage treatment, and in particular to an embedded iron-sulfur-based modified biological carrier filler, a preparation method and application thereof. Background Art

[0002] With the improvement of domestic sewage pollutant emission standards, achieving low-cost deep removal of total nitrogen and stable emission that meets standards has become a technical challenge in this field. At present, the activated sludge method is widely used in municipal sewage treatment to remove nitrogen through nitrification and denitrification processes, but this technology has some limitations: 1) When reducing carbon, the carbon and nitrogen ratio of domestic sewage is relatively low, and it is difficult to meet the heterotrophic denitrification needs relying solely on the influent carbon source, resulting in higher effluent NO3-N and causing total nitrogen to exceed the standard. Therefore, additional carbon sources need to be added, which increases a lot of costs. 2) When removing nitrogen, the traditional activated sludge method is easily affected by environmental factors such as fluctuations in influent water quality, resulting in unstable denitrification effects. It is necessary to further enhance its denitrification performance to achieve stable and deep nitrogen removal and reduce the risk of effluent water quality exceeding standards.

[0003] Therefore, in the prior art, iron-sulfur-based powder is introduced to replace part of the carbon source as an electron donor in the autotrophic denitrification process to reduce the actual amount of carbon source used to save costs. However, the amount of iron-sulfur-based powder added cannot be effectively controlled, and it cannot act efficiently on the points that need denitrification treatment. In addition, excessive addition may increase the load, resulting in unsatisfactory results. Summary of the invention

[0004] The main purpose of the present invention is to provide an embedded iron-sulfur-based modified biological carrier filler, a preparation method and its application, aiming to solve the problems of unstable denitrification effect and high cost of existing iron-sulfur-based modified biological carrier fillers.

[0005] To achieve the above-mentioned purpose, the present invention provides a method for preparing an embedded iron-sulfur-based modified biological carrier filler, comprising the steps of: mixing iron-sulfur-based powder with plastic particles to obtain a mixture; the iron-sulfur-based powder comprises iron element and / or sulfur element; injection molding the mixture to obtain an embedded iron-sulfur-based modified biological filler; wherein the mixing mass ratio of the iron-sulfur-based powder to the plastic particles is 1:10 to 100.

[0006] Furthermore, the injection molding temperature is 140-300°C; the injection molding pressure is 500-1500kg / cm 2 .

[0007] Furthermore, the particle size of the iron-sulfur based powder is 0.1 to 1000 μm.

[0008] Furthermore, the types of the iron-sulfur based powder include one or more of sulfur, pyrite, pyrite, pyrrhotite, siderite, ferrihydrite and zero-valent iron.

[0009] Furthermore, the types of the plastic particles include one or more of polypropylene, polyethylene, polystyrene, polyurethane, polycarbonate, nylon ester and polyoxymethylene.

[0010] The present invention also provides an embedded iron-sulfur-based modified biological carrier filler prepared by the preparation method as described in any one of the above items.

[0011] The present invention also provides an application of the above-mentioned embedded iron-sulfur-based modified biological carrier filler in constructing a biofilm, wherein the embedded iron-sulfur-based modified biological carrier filler is placed in a bioreactor containing activated sludge and cultured for more than 30 days to obtain a biofilm.

[0012] Furthermore, the bioreactor includes a sequencing batch bioreactor, a membrane bioreactor, an upflow anaerobic sludge blanket, a fluidized bed or a reactor for an AAO process.

[0013] The beneficial effects achieved by the present invention are:

[0014] The method for preparing the embedded iron-sulfur-based modified biological carrier filler provided by the present invention is to obtain the embedded iron-sulfur-based modified biological filler by injection molding a mixture obtained by mixing iron-sulfur-based powder and plastic particles in a mass ratio of 1:10 to 100. The method has a simple preparation process, and can obtain an embedded iron-sulfur-based modified biological filler of uniform size, which is suitable for industrial mass production; and the investment cost is low, it is easy to recycle, and the application prospect is broad.

[0015] By embedding the iron-sulfur-based powder in the suspended carrier filler, an integrated embedded iron-sulfur-based modified biological carrier filler is prepared, which has the functions of both electron donor and biofilm growth carrier. The iron-sulfur-based powder in the embedded iron-sulfur-based modified biological carrier filler can serve as an electron donor for autotrophic denitrification microorganisms, provide electrons for the denitrification process through reduced Fe and S elements, and can be placed at the desired point to attract specific functional bacteria to colonize and form a biofilm, thereby optimizing the biofilm structure.

[0016] After the embedded iron-sulfur modified biological carrier filler is applied to the activated sludge process, it can quickly cultivate and obtain biofilm (>30 days), strengthen the function of microbial denitrification effect, retain biomass by forming biofilm, further enhance nitrogen removal efficiency, improve load resistance to enhance microbial denitrification effect. It enhances the autotrophic denitrification process and reduces the proportion of heterotrophic denitrification process, thereby achieving the purpose of reducing carbon source addition, saving a lot of costs, and has great prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0018] Figure 1 The surface SEM (scanning electron microscope) morphology image and EDS (energy dispersive spectrometer) spectrum image of the embedded iron-sulfur-based modified biological carrier filler in Example 1 of the present invention; wherein (a) is the SEM image, and (b) is the EDS image;

[0019] Figure 2 The figures are actual comparison pictures of the embedded iron-sulfur-based modified biological carrier filler and the common polypropylene filler in Example 2 of the present invention; wherein (a) is an actual picture of the common polypropylene filler, and (b) is an actual picture of the embedded iron-sulfur-based modified biological carrier filler;

[0020] Figure 3 The surface SEM (scanning electron microscope) morphology image and EDS (energy dispersive spectrometer) spectrum image of the embedded iron-sulfur-based modified biological carrier filler in Example 2 of the present invention; wherein (a) is the SEM image, and (b) is the EDS image;

[0021] Figure 4 This is a comparison chart of the nitrogen removal status of the reactor before and after the addition of the embedded iron-sulfur-based modified bio-carrier filler in Example 2 of the present invention.

[0022] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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.

[0024] It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments rather than to limit the scope of protection of the present invention.

[0025] Unless otherwise defined, all technical and scientific terms used in the present invention are consistent with the prior art knowledge of those skilled in the art and the description of the present invention. The present invention can also be implemented using any methods, devices and materials in the prior art that are similar or equivalent to the methods, devices and materials described in the embodiments of the present invention.

[0026] When the embodiments give numerical ranges, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. The test methods in the following embodiments without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The materials or reagents required in the following embodiments are commercially available unless otherwise specified.

[0027] The results show that natural iron- and sulfur-containing minerals are considered to be potential high-quality autotrophic denitrification electron donors. However, the direct application of natural iron-sulfur minerals in wastewater treatment still has certain limitations. For example, their low specific surface area is not conducive to the attachment and growth of microorganisms and the formation of biofilms; their large density makes them easy to accumulate and settle at the bottom of the reactor, affecting the mass transfer efficiency; the sulfur-driven denitrification process is accompanied by a large amount of H + The acidic microenvironment produced by the direct addition of minerals is not conducive to the growth of microorganisms; the reaction speed is fast and the surface is easily passivated, affecting mass transfer.

[0028] In order to solve the problem that the total nitrogen removal rate is low when the existing sewage treatment process uses nitrification and denitrification technology for sewage treatment, in order to achieve the above purpose, the present invention provides a method for preparing an embedded iron-sulfur-based modified biological carrier filler, comprising the steps of: mixing iron-sulfur-based powder with plastic particles to obtain a mixture; the iron-sulfur-based powder includes iron and / or sulfur elements; injection molding the mixture to obtain an embedded iron-sulfur-based modified biological filler; wherein the mixing mass ratio of the iron-sulfur-based powder to the plastic particles is 1:10-100. Specifically, the embedded iron-sulfur-based modified biological carrier filler is prepared by combining the iron-sulfur-based powder with the plastic particles according to a mixing mass ratio of 1:10-100, wherein the iron-sulfur-based powder is evenly dispersed on the surface and inside of the carrier filler, continuously providing electrons for the biological denitrification process, and is more conducive to the biofilm growth of functional microorganisms that can use iron and sulfur for autotrophic denitrification. And the embedded iron-sulfur-based modified biological carrier filler is in a suspended state, which solves the shortcomings of the single iron-sulfur-based powder being easy to settle and unable to support the formation of biofilm. Compared with ordinary carrier fillers, the surface of the embedded iron-sulfur modified biological carrier filler has iron-sulfur based powder, which can specifically strengthen the autotrophic denitrification process and enhance the overall denitrification performance of the biofilm.

[0029] The method for preparing the embedded iron-sulfur-based modified biological carrier filler provided by the present invention is to obtain the embedded iron-sulfur-based modified biological filler by injection molding a mixture obtained by mixing iron-sulfur-based powder and plastic particles in a mass ratio of 1:10 to 100. The method has a simple preparation process, and can obtain an embedded iron-sulfur-based modified biological filler of uniform size, which is suitable for industrial mass production; and the investment cost is low, it is easy to recycle, and the application prospect is broad.

[0030] Furthermore, the injection molding temperature is 140-300° C. The injection molding pressure is 500-1500 kg / cm 2 .

[0031] In an optional embodiment, a Haida HDJE injection molding machine is used to mix the iron-sulfur-based powder and the raw material particles in a hopper at a ratio of 1:50, the mold and the injection system are aligned and closed, the raw material is melted into a liquid state in the injection cavity at 250-260°C and evenly wraps the iron-sulfur-based powder, and then at 800-850kg / cm 2 It is injected into the mold under pressure and dried with hot air at 60℃ for 1 hour before forming.

[0032] Furthermore, the particle size of the iron-sulfur-based powder is 0.1 to 1000 μm. Specifically, the particle size of the iron-sulfur-based powder affects the molding and mechanical strength of the filler. If the powder particle size exceeds 1000 μm, the filler will be difficult to mold, have low mechanical strength, and be easily damaged; if the powder particle size is less than 0.1 μm, the iron-sulfur element will be consumed too quickly, affecting the service life and the actual denitrification treatment effect.

[0033] Further, the types of iron-sulfur based powders include one or more of sulfur, pyrite, pyrite, pyrrhotite, siderite, ferrihydrite and zero-valent iron.

[0034] Furthermore, the types of plastic particles include one or more of polypropylene, polyethylene, polystyrene, polyurethane, polycarbonate, nylon ester and polyoxymethylene.

[0035] The present invention also provides an embedded iron-sulfur-based modified biological carrier filler prepared by any of the above preparation methods. Specifically, the structure of the embedded iron-sulfur-based modified biological carrier filler is a hollow porous insert-type spherical structure. In an optional embodiment, it is consistent with the structure of polypropylene (pp) multi-faceted hollow sphere filler.

[0036] Specifically, most traditional iron-sulfur-based mineral fillers are granular, spherical, etc. These forms of fillers have high density and mass in water, making it difficult to form a suspended and fluidized state, which results in low biofilm efficiency during application and easy accumulation in some areas. The present invention utilizes the high fluidity of traditional types of plastic carrier fillers and embeds the iron-sulfur-based powder into the traditional plastic carrier, which can achieve the advantages of both fluidity and suspension and iron-sulfur-based minerals, and solve the technical drawbacks of the prior art.

[0037] By embedding the iron-sulfur-based powder in the suspended carrier filler, an integrated embedded iron-sulfur-based modified biological carrier filler is prepared, which has the functions of both electron donor and biofilm growth carrier. The iron-sulfur-based powder in the embedded iron-sulfur-based modified biological carrier filler can serve as an electron donor for autotrophic denitrification microorganisms, provide electrons for the denitrification process through reduced Fe and S elements, and can be placed at the desired point to attract autotrophic functional bacteria to colonize and form a biofilm, thereby optimizing the biofilm structure.

[0038] The present invention also provides an application of the above embedded iron-sulfur-based modified biological carrier filler in constructing a biofilm, wherein the embedded iron-sulfur-based modified biological carrier filler is placed in a bioreactor containing activated sludge and cultured for more than 30 days to obtain a biofilm. In an optional embodiment, the embedded iron-sulfur-based modified biological carrier filler in the bioreactor containing activated sludge is set to a feed ratio of 10% to 25%. For example, the feed can be added by hanging (semi-fixed), fixed, or fluidized feeding, and the volume ratio in the reaction container is 10% to 25%.

[0039] Specifically, the biofilm constructed by the embedded iron-sulfur modified biological carrier filler can take advantage of its iron-sulfur powder in the sewage treatment process, and provide electrons for autotrophic denitrification microorganisms through iron-sulfur minerals, on the one hand, creating conditions suitable for the growth of autotrophic denitrification microorganisms, enriching autotrophic denitrification microorganisms on the surface of the carrier filler (inside the biofilm), and enhancing nitrogen removal performance. On the other hand, the electron supply of the iron-sulfur minerals it contains reduces the consumption of carbon sources (heterotrophic denitrification electron donors) and reduces costs.

[0040] After the embedded iron-sulfur modified biological carrier filler is applied to the activated sludge process, it can quickly cultivate and obtain biofilm (>30 days), strengthen the function of microbial denitrification effect, retain biomass by forming biofilm, further enhance nitrogen removal efficiency, improve load resistance to enhance microbial denitrification effect. It enhances the autotrophic denitrification process and reduces the proportion of heterotrophic denitrification process, thereby achieving the purpose of reducing carbon source addition, saving a lot of costs, and has great prospects for industrial application.

[0041] Furthermore, the bioreactor includes a sequencing batch bioreactor, a membrane bioreactor, an upflow anaerobic sludge blanket, a fluidized bed or a reactor for an AAO process.

[0042] For further understanding of the present invention, examples are given below:

[0043] Example 1

[0044] The sulfur powder is passed through a 100-mesh sieve and mixed with polypropylene particles at a mass ratio of 1:50 to obtain a mixture; the mixture is injection molded using an injection molding machine to obtain an embedded iron-sulfur-based modified bio-carrier filler.

[0045] The surface SEM (scanning electron microscope) morphology and EDS (energy dispersive spectrometer) spectrum of the embedded iron-sulfur modified biological carrier filler are shown as follows: Figure 1 (a) and (b). Figure 1 It can be observed that the sulfur powder is embedded in the surface of the polypropylene filler. The EDS spectrum results show that the distribution of sulfur elements is consistent with the distribution position of the particles, proving the successful loading of sulfur on the surface of the polypropylene filler.

[0046] Example 2

[0047] The ball-milled natural pyrite powder is passed through a 400-mesh sieve and mixed with polypropylene particles at a mass ratio of 1:50 to obtain a mixture; the mixture is injection molded using an injection molding machine to obtain an embedded iron-sulfur-based modified bio-carrier filler.

[0048] The common polypropylene filler and the obtained embedded iron-sulfur modified biological carrier filler are respectively as follows Figure 2 (a) and (b). Figure 2 It can be observed that the embedded iron-sulfur-based modified biocarrier filler is black, indicating that pyrite is successfully embedded in the polypropylene filler, and the modified filler has a uniform color, proving that pyrite is evenly distributed in the modified filler.

[0049] The morphology of the obtained embedded iron-sulfur modified biological carrier filler was analyzed, and its SEM and EDS images were shown as follows: Figure 3 As shown in (a) and (b). Figure 3 It shows that pyrite powder is loaded on the surface of polypropylene filler balls, and the EDS energy spectrum shows that the distribution position of iron elements is consistent with that of the particles, confirming the successful loading of pyrite on the surface of polypropylene filler balls.

[0050] The above-mentioned embedded iron-sulfur modified biological carrier filler was added to a 5L SBR bioreactor with a long-term stable operation in the laboratory (i.e., it has been running for more than 60 days) at a feed ratio of 25%, with NaNO3 as the influent nitrogen source and sodium acetate as the influent carbon source, C:N=3:1 (carbon source is calculated in terms of COD), and operated under HTR=48h, 30±5℃. The change in NO3-N concentration in a total of 30 days from 15 days before feeding to 15 days after feeding was recorded. The specific nitrogen removal status of the reactor before and after the addition of the embedded iron-sulfur modified biological carrier filler is shown in Figure 2. Figure 4 shown.

[0051] The results showed that the NO3-N in the effluent was about 25 mg / L within 1 to 15 days of operation, and the nitrate removal rate was only 50%. From the 15th day, the embedded iron-sulfur modified biological carrier filler (specifically, Figure 4 The NO3-N in the reactor effluent began to decrease and gradually stabilized at 10-15 mg / L, and the total nitrogen removal rate increased to 70%. This proves that the embedded iron-sulfur-based modified biological carrier filler can dissolve Fe and S to provide electrons for the denitrification process, and as a supplement to the carbon source, it plays a strengthening role in the denitrification process.

[0052] In summary, the above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing an embedded iron-sulfur modified biological carrier filler, characterized in that: Includes steps: Mixing iron-sulfur based powder with plastic particles to obtain a mixture; the iron-sulfur based powder includes iron element and / or sulfur element; Injection molding the mixture to obtain an embedded iron-sulfur-based modified biological filler; Wherein, the mixing mass ratio of the iron-sulfur based powder to the plastic particles is 1:10-100.

2. The preparation method according to claim 1, characterized in that: The injection molding temperature is 140-300°C; the injection molding pressure is 500-1500kg / cm 2 .

3. The preparation method according to claim 1, characterized in that: The particle size of the iron-sulfur based powder is 0.1 to 1000 μm.

4. The preparation method according to claim 1, characterized in that: The types of the iron-sulfur based powder include one or more of sulfur, pyrite, pyrite, pyrrhotite, siderite, ferrihydrite and zero-valent iron.

5. The preparation method according to claim 1, characterized in that: The types of the plastic particles include one or more of polypropylene, polyethylene, polystyrene, polyurethane, polycarbonate, nylon ester and polyoxymethylene.

6. An embedded iron-sulfur modified biological carrier filler prepared by the preparation method according to any one of claims 1 to 5.

7. A use of the embedded iron-sulfur modified biological carrier filler as claimed in claim 6 in constructing a biofilm, characterized in that: The embedded iron-sulfur-based modified biological carrier filler is placed in a bioreactor containing activated sludge and cultured for more than 30 days to obtain a biofilm.

8. The use according to claim 7, characterized in that: The bioreactor includes a sequencing batch bioreactor, a membrane bioreactor, an upflow anaerobic sludge bed, a fluidized bed or a reactor for an AAO process.

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