WO2024066303A1

WO2024066303A1 - Magnetic composite carrier and preparation method therefor

Info

Publication number: WO2024066303A1
Application number: PCT/CN2023/089174
Authority: WO
Inventors: 陈东之; 陈建孟; 陆李超; 李钱; 邱金锋
Original assignee: 浙江海洋大学
Priority date: 2022-09-30
Filing date: 2023-04-19
Publication date: 2024-04-04
Also published as: CN115672013A

Abstract

A magnetic composite carrier and a preparation method therefor. The magnetic composite carrier can serve as a biological carrier and is applied to a biochemical apparatus. A hollow spherical outer shell (1) is combined with an internal porous sphere (4). Therefore, the magnetic composite carrier has the characteristics of high porosity, a high specific surface area and high gas flow permeability, such that full contact between a gas flow and the carrier is ensured, a gas flow channel being unimpeded is also taken into consideration, and the pressure loss in a system is reduced. Moreover, the carrier facilitates the uniform dispersion of gas in a reactor, the space utilization rate is improved, and the area of contact between the carrier and microorganisms on the surface of a porous carrier is increased, thereby enhancing the degradation effect. In addition, by means of magnetizing the outer shell (1) and the porous sphere (4), a high-density stable heteropolar magnetic field is formed, thereby stimulating the magnetic effect of the microorganisms, improving the activity of metabolic enzymes, enhancing the biodegradation process of organic matter, and improving the purification effect of organic matter in waste gas. The carrier has relatively low production costs, is durable, achieves high efficiency and energy conservation, and can be extended to all kinds of waste gas purification processes.

Description

A magnetic composite filler and preparation method thereof

Technical Field

The present invention relates to the field of waste gas treatment technology, and specifically to a magnetic composite filler and a preparation method thereof.

Background technique

With the rapid development of industrialization in the 21st century and the gradual acceleration of the pace of modern life, various types of organic waste gas have been detected in various regions across the country, which has also caused serious pollution to the local ecological environment. At present, most waste gas treatment methods are chemical treatment or biodegradation. Among them, biotechnology is a green and clean treatment method, which degrades waste gas substances into harmless substances such as carbon dioxide and water. Since biotechnology does not produce toxic and harmful by-products during use, and its environmentally friendly characteristics, the application of biotechnology has gradually been favored by society and families. As we all know, biological filler is one of the core technologies of biodegradation of waste gas. It provides more space for microorganisms to grow; at the same time, the degradation performance of microorganisms is also closely related to the material, structure, and physical and chemical properties of the filler in the reactor.

There are many different types of biological fillers, mainly fixed fillers, hanging fillers, suspended fillers and combined fillers. The larger the contact area between the filler and the microorganism, the more corresponding attached microorganisms will be, and the conversion rate of the corresponding difficult-to-degrade substances will be greatly improved. Traditional biological fillers are generally made of a mixture of polypropylene plastics, filler foams and other polymers; but in actual application, the surface of the modified filler will gradually be smoothed under the continuous scouring of water flow, the wettability of the surface will decrease accordingly, and the corresponding hydrophilicity will deteriorate. Due to the poor hydrophilicity and biological affinity of the biological filler, the surface contact angle of the biological filler is high, and the microbial adhesion is poor, which also leads to its deficiencies in the biofilm speed, biofilm amount and the tightness between the film and the filler, further affecting the waste gas treatment efficiency. Most of the existing ones modify the biological filler by improving its surface hydrophilic affinity, but when the hydrophilicity of the modified filler is better, the thickness of the liquid film on its surface increases significantly, and the corresponding gas mass transfer resistance also increases, resulting in poor overall degradation performance. In general, the thickness of the liquid film on the surface of the packing must be strictly controlled so that it is in a suitable area to ensure normal mass transfer between gas and liquid.

In addition, with the development of waste gas biodegradation technology, more and more scientific researchers have begun to study magnetic treatment technology and apply it to the field of waste gas degradation. The traditional setting of a magnetic field outside the waste gas biodegradation reactor can greatly increase the biodegradation rate; but due to the huge space occupied by industrial waste gas treatment facilities, the cost of setting up an external magnetic field is high, which is not conducive to industrial production. On the other hand, since electric current is prone to heat generation during the magnetic generation process, there are certain safety hazards in the external magnetic field. All these factors have greatly restricted its industrial development; the built-in magnetic field can avoid such problems well, with lower production and maintenance costs, and can enhance the biodegradation of waste gas.

Summary of the invention

The present invention aims to overcome the problems in the prior art such as poor microbial adhesion, small porosity, easy clogging of fillers, and excessive pressure loss resulting in poor waste gas treatment effect, and provides a magnetic composite filler and a preparation method thereof.

To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions:

A magnetic composite filler comprises an outer shell, a cavity is arranged inside the outer shell, a flow hole connected to the cavity is also arranged on the outer shell, a porous ball is arranged in the cavity, porous filler is filled between the porous ball and the inner wall of the outer shell, and the porous ball and the outer shell are magnetic.

Most traditional biofiller structures use a hollow sphere composed of a semicircular auxiliary piece and a central axis. The filler is injection molded from polyethylene mixed with a small amount of polypropylene. It has a simple structure, low cost, large specific surface area, and is easy to form biofilms. However, when this type of biofiller degrades waste gas, the spheres collide with each other, and the various auxiliary pieces mesh and rub against each other, causing the biofilm to fall off very easily. Existing biofillers generally use a mesh cage shape composed of two grid-shaped hemispheres buckled into a grid sphere. The material is injection molded from polyethylene mixed with a small amount of polypropylene and other filling powders. This configuration is conducive to the growth of microorganisms and biofilms and can promote the degradation of organic matter by microorganisms. Because the biofilm in this type of biofiller is not easy to renew and fall off, the microorganisms in the filler grow and reproduce excessively, which easily clogs the filler, resulting in poor mass transfer performance inside and outside the mesh cage-shaped biofiller and between biofilms.

The present invention designs a magnetic composite filler. It includes an outer shell, a cavity is arranged inside the outer shell, a flow hole connected to the cavity is also arranged on the outer shell, a porous ball is arranged in the cavity, and a porous filler is filled between the porous ball and the inner wall of the outer shell. The filler is combined with the hollow outer shell and the porous ball with a hollow structure, and the internal porosity is significantly increased, which effectively avoids the clogging of the filler. The design of the flow hole is conducive to uniformly dispersing the flow direction of the gas in the system and prolonging its residence time; it also reduces the resistance encountered by the gas during the circulation process, and the pressure loss in the system is also greatly reduced. In addition, the outer shell and the porous ball are magnetized so that they have a constant weak magnetism, which is beneficial to the growth and reproduction of microorganisms. At the same time, the existence of the opposite polar magnetic field enhances the activity of the enzyme in the degradation bacteria to a certain extent, so that the degradation rate of the waste gas is accelerated. In addition, filling the porous filler between the porous ball and the inner wall of the outer shell helps to promote the attachment of microorganisms to the porous filler; this also increases the contact area of the microorganisms on the porous filler, and promotes more microorganisms to have a magnetic effect. By adopting an outer shell filled with a static magnetic field in all directions and assembling and matching porous balls with porous fillers, a magnetic composite filler with stable performance is formed, thereby effectively improving its degradation effect on exhaust gas.

Preferably, the outer shell includes two upper and lower half shells, and the half shells are interlocked with each other to form a complete spherical outer shell.

As a further preference, the outer shell can be a polyhedral sphere, or a hollow sphere, or a solid spherical structure, and the outer shell has a large surface area.

The structure of a complete spherical outer shell is formed by inserting the upper and lower half shells into each other, so that the gas in the system is blocked by the spherical surface when passing through the outer shell, which also causes the gas flow to bend and tilt to a certain extent, thereby reducing the intake rate of the exhaust gas. At the same time, the movement path of the airflow is extended, which causes the gas to gradually increase its residence time in the system. These changing factors promote the full contact between microorganisms and exhaust gas to a certain extent, and it also further improves the degradation performance of microorganisms on exhaust gas.

Preferably, the outer shell is provided with flow plates which are arranged radially and staggered, and flow holes which are connected to the cavity are formed between adjacent flow plates.

Setting up multiple circulation sheets effectively increases the specific surface area of the magnetic composite filler, which is conducive to the growth of microorganisms. The design of the circulation holes is conducive to the uniform dispersion of the gas in the system and prolonging its residence time. The resistance encountered by the gas during the circulation process is reduced, and the pressure loss in the system is also greatly reduced.

Preferably, two connecting rods for fixing to the outer shell are symmetrically arranged on the outer surface of the porous ball, so that the porous ball can be suspended inside the cavity through the connecting rods.

As a further preference, the porous ball has a hollow structure inside, and the porous ball is formed by two left and right porous hemispheres interlocked with each other. There is a certain gap between the left and right porous hemispheres.

The porous ball is suspended inside the cavity by a connecting rod, and its internal porosity exceeds 90%, which can effectively avoid clogging of the filler. At the same time, during the degradation process, the porous filler is fixedly filled between the porous ball and the inner wall of the shell, and less than 50% of the space is occupied by microorganisms. The presence of the porous ball with a hollow structure inside further promotes that the pressure loss in the system is always small.

Preferably, the pore size of the porous filler is 0.5~2mm and the porosity is greater than 90%.

As a further preference, the porous filler is a combination of one or more of burr balls, polyurethane foam, and polyurethane sponge.

The porosity of the porous filler is greater than 90%, which is beneficial to enhance the adhesion of microorganisms on the surface of the porous filler. At the same time, the pore size of the porous filler is selected to be 0.5~2mm, which plays a role in drainage and dispersion of the gas in the system. When the pore size is less than 0.5 mm, the porous filler is approximately a solid structure. It is difficult for the gas to pass through when it flows in, and the resistance encountered is too large, and the corresponding pressure loss will increase. When the pore size is greater than 2mm, the gas passes directly through when it flows in; although it is not subject to resistance, it has no drainage and dispersion effect, which indirectly shortens the residence time of the gas in the system, further affecting the waste gas degradation rate. In addition, the porous filler is fixedly filled between the porous ball and the inner wall of the shell, which is beneficial to the renewal and shedding of the biofilm on the surface of the porous filler.

Preferably, the outer shell and porous balls include the following components in parts by weight: 60-90 parts of plastic, 2-5 parts of activated carbon, 5-15 parts of magnetic powder, 0.5-4 parts of liquid dispersant, 0.5-3 parts of silane coupling agent, 1-3 parts of starch, 1.5-4 parts of diatomaceous earth, 1-5 parts of hydroxyapatite, and 1-5 parts of polyvinyl alcohol.

As a further preference, the magnetic powder is a combination of one or more of barium ferrite magnetic powder, cobalt ferrite magnetic powder, and iron oxide magnetic powder.

There are a small amount of metal elements in the enzymes in the degradation bacteria, all of which have certain paramagnetic properties. Under the action of the heteropolar magnetic field, they will rearrange and move along the direction of the magnetic field. These influencing factors increase the activity of the enzyme. Since the enzyme activity helps to promote the metabolism in the microorganisms, this also gradually increases the degradation rate of waste gas. In addition, since the degradation bacteria themselves have certain magnetism, under the action of the heteropolar magnetic field, the degradation bacteria are more easily adsorbed on the surface of the magnetic composite filler, which also increases the number of microorganisms on the surface of the magnetic composite filler, and ultimately improves the overall degradation performance of the waste gas.

On the other hand, under a constant weak magnetic field environment, the concentration of dissolved oxygen in water will show an increasing trend. Oxygen, as a paramagnetic substance, produces active oxygen with high oxidizing properties, which accelerates the oxidation of organic pollutants in water; the corresponding enzyme activity shows a trend of gradual increase, which eventually leads to a decrease in the concentration of organic pollutants in water. At the same time, during aeration, oxygen will be adsorbed near the magnetic composite filler under the action of the magnetic field, which will also increase the oxygen concentration on the surface of the magnetic composite filler, further promoting the reproduction of aerobic microorganisms.

Each filler with added magnetic powder is equivalent to a miniature biological contact oxidation reactor with a magnetic field, allowing oxygen and microorganisms to attach to the surface of the magnetic composite filler more quickly; this can also effectively shorten the film formation time and improve the waste gas degradation effect.

Activated carbon, starch, diatomaceous earth, hydroxyapatite and polyvinyl alcohol can all provide good nutrition and growth environment for the growth and reproduction of microorganisms. They can increase the number of microorganisms attached to the surface of magnetic composite fillers to a certain extent, thereby improving the biological activity of microorganisms and ultimately accelerating the biodegradation rate of waste gas.

Starch is a polyglucose that can provide sufficient nutrients for microorganisms. The addition of starch enhances the affinity between the magnetic composite filler and microorganisms, and can also be used as a pore-forming agent. When the magnetic composite filler degrades waste gas, the starch dissolves in water or is consumed by microorganisms, resulting in a large number of voids on the surface of the magnetic composite filler, which also increases the specific surface area of the magnetic composite filler and the corresponding porosity, which increases the number of microorganisms attached to the filler surface. The micropores formed by starch are conducive to the growth and reproduction of microorganisms. When it reaches a certain level, it also further adjusts the density of the magnetic composite filler.

Activated carbon has excellent adsorption properties. When the weight of activated carbon is less than 2 parts, the amount of biofilm increases significantly with the increase of activated carbon addition. When the weight of activated carbon exceeds 5 parts, it has basically no effect. Diatomaceous earth has excellent properties such as large specific surface area, high porosity, large adsorption capacity and good adsorption due to its unique multi-level pore structure. It is beneficial to improve the microbial adhesion on the surface of magnetic composite fillers; at the same time, because it contains a small amount of organic matter, it can also provide certain nutrients for microorganisms. Hydroxyapatite can participate in metabolism in organisms and has good biological activity. It can provide nutrients for microorganisms. Polyvinyl alcohol has good film-forming properties and good hydrophilicity, which is conducive to biodegradation.

Preferably, the liquid dispersant is white mineral oil, vegetable oil or a combination of both.

Add white mineral oil and vegetable oil liquid dispersants to the plastic particles, mix and stir them thoroughly, which is conducive to the liquid dispersant sticking to the surface of the plastic particles more evenly, making it difficult to fall off and evenly dispersed. The introduction of dispersants helps to increase the roughness of the plastic particle surface and improve the adhesion of microorganisms. In addition, white mineral oil and vegetable oil liquids also play a good lubricating role in the subsequent plastic granulation process.

Preferably, the plastic is a combination of one or more of polyethylene, polypropylene, and acrylonitrile-butadiene-styrene copolymer.

Plastics choose thermoplastic resin materials, which are non-toxic to microorganisms, have good biological adaptability, and are beneficial to the growth and reproduction of microorganisms. Because thermoplastic resin materials have good plasticity, good thermal stability and are easy to process and shape; they also have good chemical stability and strong acid and alkali corrosion resistance; their corresponding impact resistance is excellent, which is also beneficial to prevent filler aging and extend service life.

A method for preparing a magnetic composite filler comprises the following steps:

(S.1) crushing, sieving and classifying plastic, activated carbon, silane coupling agent, starch, diatomaceous earth, hydroxyapatite and polyvinyl alcohol, heating and drying, and naturally cooling to room temperature to obtain a solid mixed raw material;

(S.2) fully mixing the solid mixed raw material and the liquid dispersant in step (S.1), adding magnetic powder, stirring evenly and granulating to obtain a mixed filler;

(S.3) injection molding the mixed filler in step (S.2), and then magnetizing to obtain the outer shell and the porous ball;

(S.4) Assembling and fixing the outer shell and porous balls obtained in step (S.3) with the porous filler to obtain a magnetic composite filler.

The specific preparation method of the present invention is:

(S.1) 60-90 parts of plastic, 2-5 parts of activated carbon, 0.5-3 parts of silane coupling agent, 1-3 parts of starch, 1.5-4 parts of diatomaceous earth, 1-5 parts of hydroxyapatite, and 1-5 parts of polyvinyl alcohol are mixed and crushed, sieved through a 200-500 mesh sieve and classified, and then heated and dried at 50-90° C. for 5-48 hours, and naturally cooled to room temperature to obtain a solid mixed raw material;

(S.2) The solid mixed raw material in step (S.1) is thoroughly mixed with 0.5-4 parts of liquid dispersant until droplets adhere to the surface of the solid mixed raw material but do not fall off. Then 5-15 parts of magnetic powder are added, stirred evenly and granulated to obtain a mixed filler;

(S.3) adding the mixed filler in step (S.2) into an injection molding machine, performing injection molding at 140-180° C. to obtain the outer shell and the porous ball, and then placing them into a magnetizer of 8000-20000 GS for magnetization, so that the outer shell and the porous ball have a constant magnetic field of 20-100 GS;

(S.4) The porous filler is cleaned, decontaminated and dried using an acid having a concentration of 5 to 25% and an alkali having a concentration of 10 to 30%. The outer shell and porous balls magnetized in step (S.3) are assembled and fixed with the porous filler after decontamination and drying to obtain a magnetic composite filler.

As a preference, the width of the sieve used in the step (S.1) is 200-500 mesh, and after sieving, the sieve is dried at 50-90°C for 5-48 hours;

In the step (S.3), the mixed filler is injection molded at 140-180° C., and then placed in a magnetizer of 8000-20000 GS for magnetization, so that the outer shell and the porous ball have a constant magnetic field of 20-100 GS;

The porous filler in the step (S.4) is cleaned and dried by successively using 5-25% acid and 10-30% alkali.

The screen width used in the sieving in step (S.1) is 200-500 mesh, which is conducive to removing large particle impurities and maintaining uniform particle size. At the same time, the particle density difference is small, the mixing uniformity is higher, and the structure of the injection molded outer shell and porous ball is more stable.

When the amount of magnetic powder added in step (S.2) is less than 5 parts, the iron oxide content in the magnetic powder is low, which will directly lead to poor magnetization effect after injection molding of the mixed filler in the subsequent steps. The magnetic composite filler after magnetization has a certain weak magnetic field, and the degradation rate of waste gas by microorganisms attached to its surface will increase with the increase of magnetic field strength. Magnetic powder has the highest density in the entire magnetic composite filler component. When the amount of magnetic powder added exceeds 15 parts, a density difference will occur during the granulation process, which seriously affects the mixing uniformity. In addition, in the subsequent injection molding process, when the amount of magnetic powder added is too much, the dispersibility is poor and compression molding is difficult. Sedimentation is very easy to occur, which directly affects the normal molding of the injection molding machine and leads to a high rate of defective injection molded parts.

In step (S.3), the temperature of the mixed filler injection molding is lower than 140°C or higher than 180°C, which will affect the rheological properties of the mixed filler at high temperature, affect the mixing uniformity, and further affect the quality of the injection molded parts. On the other hand, the outer shell and the porous ball have a constant weak magnetic field of 20~100GS, which can improve the activity of the degradation bacteria and effectively stimulate the growth and metabolism of microorganisms. A strong magnetic field exceeding 100GS will inhibit the activity of the degradation bacteria, resulting in a poor degradation effect and a reduced waste gas degradation rate.

As a further preference, the acid is generally an inorganic acid, which may be nitric acid, sulfuric acid, or hydrochloric acid, and the alkaline solution may be a sodium hydroxide solution, a potassium hydroxide solution, or a sodium carbonate solution.

In step (S.4), the porous filler is washed with acid and alkali successively, which can effectively remove impurities in the porous filler. At the same time, it is helpful to increase the roughness of the surface of the porous filler and further enhance the adhesion of microorganisms.

Therefore, the present invention has the following beneficial effects:

(1) The present invention effectively improves the internal porosity of the outer shell and the porous ball by fixing them together, and with multiple flow holes, the gas flow channels are increased, and the pressure loss in the system is significantly reduced;

(2) The present invention uses a uniquely designed biofiller to guide the gas to disperse evenly in the reactor, further extending its residence time and enhancing the degradation effect in the biochemical reaction;

(3) The present invention magnetizes the outer shell and the porous ball, and then fills the porous filler. This allows a large amount of high-density heteropolar magnetic fields to gather in the magnetic composite filler, increasing the contact area between the magnetic composite filler and the microorganisms attached to the surface of the porous filler. Under the action of the heteropolar magnetic field, more microorganisms are encouraged to produce magnetic effects, further increasing the activity of enzymes in the microorganisms.

(4) The present invention has low production cost, is durable, and is highly efficient and energy-saving, which is conducive to promotion and application in production practice.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of the structure of the magnetic composite filler when it is not filled with porous filler;

FIG2 is a schematic diagram of the structure of a half shell;

FIG3 is a schematic diagram of the structure of a porous ball;

FIG4 is a schematic diagram of an explosion of a magnetic composite filler;

FIG5 is a flow chart of the preparation process of magnetic composite fillers;

FIG6 is a graph showing the change in chlorobenzene concentration in a shake flask experiment;

FIG7 is a graph showing the concentration variation of carbon dioxide generated in a shake flask experiment;

FIG8 is a graph showing the change in chloride ion concentration in the solution after degradation of chlorobenzene waste gas;

FIG9 is a graph showing changes in dehydrogenase activity (DHA) of the aqueous phase and microorganisms on the filler in a shake flask experiment;

FIG10 is a graph showing the change in chlorobenzene concentration and cell dry weight under different magnetic fields in a shake flask experiment;

Figure 11 is a schematic diagram of magnetic fields of the same level (different polarity);

FIG12 is a schematic diagram of the magnetic field after the porous ball is magnetized;

FIG13 is a schematic diagram of the magnetic field after the circulation sheet on the outer shell is magnetized;

FIG. 14 is a graph showing the changes in chlorobenzene concentration and chlorobenzene removal rate in the trickling tower.

In the figure: outer shell 1; cavity 2; flow hole 3; porous ball 4; porous filler 5; half shell 6; flow sheet 7; connecting rod 8.

Implementation

The present invention is further described below in conjunction with the drawings and specific embodiments of the specification. A person of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only part of the embodiments of the present invention, rather than all of the embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without making any creative work should fall within the scope of protection of the present invention.

Example 1

The implementation method of magnetic composite filler is as follows:

As shown in Figures 1-4, the magnetic composite filler includes an outer shell 1, and a cavity 2 is arranged inside the outer shell 1. The outer shell 1 is also provided with a flow hole 3 connected to the cavity 2. A porous ball 4 is arranged in the cavity 2, and a porous filler 5 is filled between the porous ball 4 and the inner wall of the outer shell 1. In this embodiment, the actual position of the porous filler 5 is between the porous ball 4 and the inner wall of the outer shell 1. Figure 4 is only an exploded schematic diagram of the hollow ball of the magnetic composite filler, and does not represent the actual position of each structure.

The outer shell 1 includes two upper and lower half shells 6, which are interlocked with each other to form a complete spherical outer shell 1.

As another embodiment, the outer shell 1 can be a polyhedral sphere, a hollow sphere, or a solid spherical structure, so that the outer shell 1 has a large surface area.

The upper and lower half shells 6 are interlocked to form a complete spherical outer shell 1, so that the gas in the system is blocked by the spherical surface when passing through the outer shell 1. This causes the gas flow direction to bend and tilt to a certain extent, thereby reducing the intake rate of the exhaust gas. At the same time, the gas flow path becomes longer, which prolongs the residence time of the gas in the system. This is conducive to promoting more complete contact between microorganisms and exhaust gas, and further improving the degradation performance of microorganisms on exhaust gas.

The outer shell 1 is provided with radially staggered flow sheets 7, and flow holes 3 connected to the cavity 2 are formed between adjacent flow sheets 7. The provision of multiple flow sheets 7 effectively increases the specific surface area of the magnetic composite filler, which is conducive to the growth of microorganisms and biofilm. The design of the flow holes 3 is conducive to uniformly dispersing the direction of the gas in the system and prolonging its residence time. The resistance encountered by the gas during the circulation process is reduced, and the pressure loss in the system is also greatly reduced.

Two connecting rods 8 for fixing to the outer shell 1 are symmetrically arranged on the outer surface of the porous ball 4, so that the porous ball 4 can be suspended inside the cavity 2 through the connecting rods 8.

As another embodiment, the porous ball 4 has a hollow structure inside, and the porous ball 4 is formed by two left and right porous hemispheres interlocked with each other. There is a certain gap between the left and right porous hemispheres.

The porous ball 4 is suspended inside the cavity 2 by the connecting rod 8, and its internal porosity exceeds 90%, which can effectively avoid the clogging of the filler. At the same time, during the degradation process, the porous filler 5 is fixedly filled between the porous ball 4 and the inner wall of the outer shell 1, and less than 50% of the space is occupied by microorganisms. The presence of the porous ball 4 with a hollow structure inside further promotes that the pressure loss in the system is always small.

The pore size of the porous filler 5 is 0.5~2mm, and the porosity is greater than 90%.

As another embodiment, the porous filler 5 is a combination of one or more of burr balls, polyurethane foam, and polyurethane sponge.

The porosity of the porous filler 5 is greater than 90%, which is conducive to enhancing the adhesion of microorganisms on the surface of the porous filler 5. At the same time, the pore size of the porous filler 5 is selected to be 0.5~2mm, which plays a role in drainage and dispersion of the gas in the system. When the pore size is less than 0.5 mm, the porous filler 5 is approximately a solid structure. It is difficult for the gas to pass through when it flows in, and the resistance encountered is too large, and the corresponding pressure drop will increase. When the pore size is greater than 2mm, the gas passes directly through when it flows in. Although it is not subject to resistance, there is no drainage and dispersion effect. It indirectly shortens the residence time of the gas in the system, further affecting the waste gas degradation rate. In addition, the porous filler 5 is fixedly filled between the porous ball 4 and the inner wall of the outer shell 1, which is conducive to the renewal and shedding of the biofilm on the surface of the porous filler 5.

Example 2

(S.1) 74 parts of polypropylene, 4 parts of activated carbon, 1 part of silane coupling agent KH-570, 2.5 parts of starch, 2 parts of diatomaceous earth, 3.5 parts of hydroxyapatite, and 1.5 parts of polyvinyl alcohol are mixed and crushed, sieved through a 200-300 mesh sieve and classified, and then heated and dried at 50° C. for 10 hours, and naturally cooled to room temperature to obtain a solid mixed raw material;

(S.2) The solid mixed raw material in step (S.1) is thoroughly mixed with 1 part of white mineral oil and 0.5 parts of vegetable oil until droplets adhere to the surface of the solid mixed raw material but do not fall off. Then 10 parts of magnetic powder are added, stirred evenly and granulated to obtain a mixed filler;

(S.3) adding the mixed filler in step (S.2) into an injection molding machine, injection molding at 140° C. to obtain the outer shell and porous balls, and then placing them into a 10000GS magnetizer for magnetization, so that the outer shell and porous balls have a constant magnetic field of 20GS;

(S.4) The porous filler is cleaned and dried by using 5% nitric acid and 10% sodium hydroxide respectively. Then, the outer shell and porous balls magnetized in step (S.3) are assembled and fixed with the porous filler after impurities are removed and dried to obtain a magnetic composite filler.

Example 3

(S.1) 74 parts of polypropylene, 4 parts of activated carbon, 1 part of silane coupling agent KH-570, 1 part of starch, 2 parts of diatomaceous earth, 3.5 parts of hydroxyapatite, and 1.5 parts of polyvinyl alcohol are mixed and crushed, sieved through a 200-300 mesh sieve and classified, and then heated and dried at 50° C. for 10 hours, and naturally cooled to room temperature to obtain a solid mixed raw material;

Example 4

(S.1) 74 parts of polypropylene, 4 parts of activated carbon, 1 part of silane coupling agent KH-570, 3 parts of starch, 2 parts of diatomaceous earth, 3.5 parts of hydroxyapatite, and 1.5 parts of polyvinyl alcohol are mixed and crushed, sieved through a 200-300 mesh sieve and classified, and then heated and dried at 50° C. for 10 hours, and naturally cooled to room temperature to obtain a solid mixed raw material;

Example 5

(S.2) The solid mixed raw material in step (S.1) is thoroughly mixed with 1 part of white mineral oil and 0.5 parts of vegetable oil until droplets adhere to the surface of the solid mixed raw material but do not fall off. Then 5 parts of magnetic powder are added, stirred evenly and granulated to obtain a mixed filler;

Example 6

(S.2) The solid mixed raw material in step (S.1) is thoroughly mixed with 1 part of white mineral oil and 0.5 parts of vegetable oil until droplets adhere to the surface of the solid mixed raw material but do not fall off. Then 15 parts of magnetic powder are added, stirred evenly and granulated to obtain a mixed filler;

Example 7

(S.2) The solid mixed raw material in step (S.1) is thoroughly mixed with 0.5 parts of white mineral oil and 1.5 parts of vegetable oil until droplets adhere to the surface of the solid mixed raw material but do not fall off. Then 10 parts of magnetic powder are added, stirred evenly and granulated to obtain a mixed filler;

Example 8

(S.2) The solid mixed raw material in step (S.1) is thoroughly mixed with 4 parts of white mineral oil and 3 parts of vegetable oil until droplets adhere to the surface of the solid mixed raw material but do not fall off. Then 10 parts of magnetic powder are added, stirred evenly and granulated to obtain a mixed filler;

Example 9

(S.1) 60 parts of polypropylene, 2 parts of activated carbon, 0.5 parts of silane coupling agent KH-570, 2.5 parts of starch, 1.5 parts of diatomaceous earth, 1 part of hydroxyapatite, and 1 part of polyvinyl alcohol are mixed and crushed, sieved through a 200-300 mesh sieve and classified, and then heated and dried at 50° C. for 10 hours, and naturally cooled to room temperature to obtain a solid mixed raw material;

Example 10

(S.1) 90 parts of polypropylene, 5 parts of activated carbon, 3 parts of silane coupling agent KH-570, 2.5 parts of starch, 4 parts of diatomaceous earth, 5 parts of hydroxyapatite, and 5 parts of polyvinyl alcohol are mixed and crushed, sieved through a 200-300 mesh sieve and classified, and then heated and dried at 50° C. for 10 hours, and naturally cooled to room temperature to obtain a solid mixed raw material;

Comparative Example 1

(S.2) The solid mixed raw material in step (S.1) is thoroughly mixed with 1 part of white mineral oil and 0.5 parts of vegetable oil until droplets adhere to the surface of the solid mixed raw material but do not fall off. Stir evenly and granulate to obtain a mixed filler;

Comparative Example 2

(S.2) The solid mixed raw material in step (S.1) is thoroughly mixed with 1 part of white mineral oil and 0.5 parts of vegetable oil until droplets adhere to the surface of the solid mixed raw material but do not fall off. Then 2 parts of magnetic powder are added, stirred evenly and granulated to obtain a mixed filler;

Comparative Example 3

(S.2) The solid mixed raw material in step (S.1) is thoroughly mixed with 1 part of white mineral oil and 0.5 parts of vegetable oil until droplets adhere to the surface of the solid mixed raw material but do not fall off. Then 20 parts of magnetic powder are added, stirred evenly and granulated to obtain a mixed filler;

Comparative Example 4

(S.1) 74 parts of polypropylene, 4 parts of activated carbon, 1 part of silane coupling agent KH-570, 2 parts of diatomaceous earth, 3.5 parts of hydroxyapatite, and 1.5 parts of polyvinyl alcohol are mixed and crushed, sieved through a 200-300 mesh sieve and classified, and then heated and dried at 50° C. for 10 hours, and naturally cooled to room temperature to obtain a solid mixed raw material;

Comparative Example 5

(S.1) 74 parts of polypropylene, 4 parts of activated carbon, 1 part of silane coupling agent KH-570, 0.5 parts of starch, 2 parts of diatomaceous earth, 3.5 parts of hydroxyapatite, and 1.5 parts of polyvinyl alcohol are mixed and crushed, sieved through a 200-300 mesh sieve and classified, and then heated and dried at 50° C. for 10 hours, and naturally cooled to room temperature to obtain a solid mixed raw material;

Comparative Example 6

(S.1) 74 parts of polypropylene, 4 parts of activated carbon, 1 part of silane coupling agent KH-570, 5 parts of starch, 2 parts of diatomaceous earth, 3.5 parts of hydroxyapatite, and 1.5 parts of polyvinyl alcohol are mixed and crushed, sieved through a 200-300 mesh sieve and classified, and then heated and dried at 50° C. for 10 hours, and naturally cooled to room temperature to obtain a solid mixed raw material;

Comparative Example 7

(S.2) adding 10 parts of magnetic powder to the solid mixed raw material in step (S.1), stirring and granulating to obtain a mixed filler;

Comparative Example 8

(S.2) The solid mixed raw material in step (S.1) is thoroughly mixed with 6 parts of white mineral oil and 5 parts of vegetable oil until droplets adhere to the surface of the solid mixed raw material but do not fall off. Then 10 parts of magnetic powder are added, stirred evenly and granulated to obtain a mixed filler;

Comparative Example 9

(S.3) adding the mixed filler in step (S.2) into an injection molding machine, and performing injection molding at 140° C. to obtain the outer shell and the porous ball;

(S.4) The porous filler is cleaned and dried by using 5% nitric acid and 10% sodium hydroxide respectively. Then, the outer shell and porous balls in step (S.3) are assembled and fixed with the porous filler after cleaning and drying to obtain a composite filler.

【Performance testing and analysis】

【Experiment 1】Determination of chlorobenzene concentration in shake flask experiment

The magnetic composite filler was obtained according to the preparation methods of Examples 2 to 10 and Comparative Examples 1 to 8, and the composite filler was obtained according to the preparation method of Comparative Example 9. A 310 mL sealed bottle was used as the biological reaction system, and blank, composite filler, and magnetic composite filler were added to three sealed bottles in sequence, thereby forming three experimental groups, namely: blank group, modified group, and modified magnetized group. A certain amount of inorganic salt culture medium and 1 mL of XCW-1 bacterial solution activated to the logarithmic growth phase (the strain selected in this experiment was a chlorobenzene efficient degradation bacterium-Relstoniajolanacearum XCW-1 screened from the activated sludge of a chemical plant in Zhejiang) were added to the three experimental groups at the same time, so that the total volume of the liquid phase was 100 mL, and then 9 μL of chlorobenzene with a concentration of 100 mg·L ^-1 (Shanghai McLean Biological Brand, available on the market) was added. Then the sealed bottles were placed in a shaking incubator with a temperature of 30°C and a rotation speed of 160 r·min ^-1 for shaking culture, and 0.8 mL of the gas in the bottle was taken every 4 to 5 h, and each group of experiments was repeated three times.

The concentration of chlorobenzene in the gas phase was quantitatively analyzed by gas chromatograph (Agilent 6890, USA). The chromatographic column was a HP-Innowax capillary column (30 m×0.32 mm×0.5 μm) corresponding to the FID detector. The vaporization chamber and detector temperatures were 200 ℃ and 180 ℃, respectively, and the column temperature was 100 ℃. Carrier gas: nitrogen; column flow: 1 mL·min ^-1 ; split ratio: 30:1; injection volume: 800 μL. The concentration of the corresponding substrate chlorobenzene in each experimental group was determined according to the calibration curve method. The curve of the concentration of chlorobenzene (mg·m ^-3 ) and the peak area in this test was Y=1.8776X－573.39, R ² =0.9981.

The change of chlorobenzene concentration in the shake flask experiment is shown in Figure 6.

From the data analysis and comparison in Figure 6, it can be seen that the modified magnetized group has completely degraded chlorobenzene within 18 hours, while the modified group and the blank group need to delay 1 to 2 hours to achieve the same effect, which also shows that the microbial degradation rate of the modified magnetized group is higher than that of the other two experimental groups. Degradation bacteria are attached to the surface of the magnetic composite filler in the modified magnetized group, and the degrading bacteria contain a small amount of paramagnetic metal elements. Under the action of the static magnetic field, these metal elements are rearranged, thereby inducing the activity and synthesis of the enzymes in the degrading bacteria; this also further promotes the biofilm growth and metabolism of the degrading bacteria on the surface of the magnetic composite filler, thereby accelerating its degradation rate.

【Experiment 2】Determination of carbon dioxide concentration in shake flask experiment

The magnetic composite filler was obtained according to the preparation methods of Examples 2 to 10 and Comparative Examples 1 to 8, and the composite filler was obtained according to the preparation method of Comparative Example 9. A 310 mL sealed bottle was used as the biological reaction system, and blank, composite filler, and magnetic composite filler were added to three sealed bottles in sequence; thereby forming three experimental groups, namely: blank group, modified group, and modified magnetized group. A certain amount of inorganic salt culture medium and 1 mL of XCW-1 bacterial liquid activated to the logarithmic growth phase (the strain selected in this experiment was a chlorobenzene efficient degradation bacterium-Relstoniajolanacearum XCW-1 screened from the activated sludge of a chemical plant in Zhejiang) were added to the three experimental groups at the same time, so that the total volume of the liquid phase was 100 mL. Then add 9 μL of 100 mg·L ^-1 chlorobenzene (Shanghai McLean Biotech, commercially available); then place the sealed bottle in a shaker at 30°C and 160 r·min ^-1 for shaking culture. Take 0.8 mL of the gas in the bottle every 4 to 5 h. Repeat each experiment three times and measure the concentration of carbon dioxide generated using a gas chromatograph.

The concentration of CO ₂ in the gas phase was quantitatively analyzed by gas chromatograph (Agilent 6890, USA). The chromatographic column was a HP-Plot-Q capillary column (30 m×0.32 mm×20 μm) corresponding to the TCD detector. The injection port and detector temperatures were 90 ℃ and 180 ℃, respectively, and the column temperature was 40 ℃. Carrier gas: N ₂ ; total flow rate: 107 mL·min ^-1 ; split ratio: 50:1; gas injection volume: 800 μL. The concentration of generated carbon dioxide was measured by gas chromatograph according to the calibration curve method. The curve of CO ₂ concentration (mg·L ^-1 ) and the measured peak area in this test was Y=0.3363X+0.3397, R ² =0.9996.

The concentration change of carbon dioxide generated in the shake flask experiment is shown in Figure 7.

From the data analysis in Figure 7, it can be seen that as the reaction time increases, the concentration of carbon dioxide generated gradually increases. After 15 hours of reaction, the concentration of carbon dioxide generated by the modified magnetized group is significantly higher than that of the other two experimental groups, and the rate of carbon dioxide generation is faster. When the degradation reaction lasts for 24 hours, the concentration of carbon dioxide generated in this experiment reaches a peak value, corresponding to 46 mg·L ^-1 , which also shows that the modified magnetized group has a better degradation effect on chlorobenzene waste gas. Chlorobenzene waste gas diffuses from the gas phase to the liquid phase surface, and then diffuses from the liquid phase surface to the interface between the liquid phase and the biofilm, where it is degraded into carbon dioxide and water by microorganisms in the biofilm. In addition, chlorobenzene waste gas is used by the microbial cells themselves to discharge carbon dioxide through diffusion; therefore, the concentration of carbon dioxide at the outlet represents the intensity of the carbon source of microbial metabolism. The higher the concentration of carbon dioxide at the outlet, the more chlorobenzene waste gas is degraded by microorganisms.

【Test 3】Determination of chloride ion concentration in solution

After the shake flask experiment in Experiment 1 or Experiment 2 is completed, 1 mL of solution is taken and detected by ICS-2000 ion chromatography. The separation column is AS19 (4.0×250 mm), the conductivity detector is 35 ℃, the eluent is KOH (concentration gradient 10~40 mmol·L ^-1 ), the flow rate is 1.00 mL·min ^-1 , the injection volume is 25 μL, and the sample is filtered through a 0.45 μm filter membrane and a sodium cation exchange column before injection. The chloride ion concentration in the solution is measured according to the calibration curve method. The curve of chloride ion concentration (mg·L ^-1 ) and the measured peak area in this test is Y=3.3197X+0.0344, R ² =0.999.

The change in chloride ion concentration in the solution after degradation of chlorobenzene waste gas is shown in Figure 8.

From the data analysis and comparison in Figure 8, it can be seen that after the modified magnetized group degraded chlorobenzene waste gas, the chloride ion concentration in the solution was always higher than that in other experimental groups. This phenomenon also corresponds to the performance difference in the reaction system, indicating that the modified magnetized group has better performance in product metabolism. The degradation rate of the substrate in the modified magnetized group was fast and the reaction was complete, while the reaction in the degradation process of the other experimental groups was not thorough enough, resulting in a part of chloride ions in the intermediate product, which led to a lower chloride ion concentration in the solution.

[Experiment 4] Determination of dehydrogenase activity (DHA) of microorganisms in the aqueous phase and on the filler in a shake flask experiment

After the shake flask experiment in Experiment 1 or Experiment 2 is completed, the aqueous phase in the corresponding shake flasks of the three experimental groups is used as the test solution. 0.3 mL of the test solution, 1.5 mL of Tris-HCl buffer (pH=7.5), and 1 mL of 0.2% INT (iodonitrotetrazolium violet) solution are added to a 10 mL centrifuge tube in sequence (1 mL of pure water is added to the blank tube). Rapidly place the prepared sample in a 37 ℃ water bath and shake incubate for 30 min, add 1 mL of 37% formaldehyde to terminate the enzyme reaction; centrifuge at 5000 r·min ^-1 for 5 min, gently discard the supernatant, add 5 mL of methanol, mix and stir evenly, continue to shake and extract in the dark at 37 ℃ for 10 min, centrifuge at 4000 r·min ^-1 for another 5 min, take the supernatant and measure the absorbance at 485 nm, and measure the dehydrogenase activity in the solution according to the calibration curve method. In this test, the curve of dehydrogenase activity (µmol·ml ^-1 ·h ^-1 ) and measured absorbance is Y=0.8601X+0.018, R ² =0.9969.

The changes in dehydrogenase activity (DHA) of microorganisms in the solution and on the filler after degrading chlorobenzene waste gas are shown in Figure 9.

From the data analysis and comparison in Figure 9, it can be seen that after the modified magnetized group degraded chlorobenzene waste gas, the dehydrogenase activity on the filler was always higher than that of other experimental groups. Since the surface of the filler is uneven, it provides a large amount of growth space for microorganisms. In addition, microorganisms can attach to the surface of the filler and grow normally. The nutrients inside the filler can also promote the growth of microorganisms. Usually, microorganisms are generally negatively charged, and magnetized fillers are easily attached to them by microorganisms. This further shows that the modified magnetized group has a faster degradation rate and better performance in corresponding metabolism.

The dehydrogenase activity of all groups in the water phase is always weaker than that on the filler. This may be because the microorganisms in the water are easily dispersed by the water flow, have no carrier to attach to, and have insufficient resistance to environmental impact, which also causes their overall dehydrogenase activity to be low.

[Experiment 5] Determination of substrate degradation rate under different magnetic fields in shake flask experiment

A 310 mL sealed bottle was used as the biological reaction system. Magnets were reinforced on both sides of two sealed bottles (the magnetic field strength in the middle was 20 mT), forming stable homopolar magnetic fields and heteropolar magnetic fields respectively. At the same time, a blank was added to the third sealed bottle so that it had no magnetic field, thus forming three experimental groups. The three experimental groups were: homopolar magnetic field group, heteropolar magnetic field group, and blank group. A certain amount of inorganic salt culture medium and 1 mL of XCW-1 bacterial solution activated to the logarithmic growth phase were added to the three experimental groups at the same time (the strain selected in this experiment was a chlorobenzene-efficient degradation bacterium, Relstonia jolanacearum XCW-1, screened from the activated sludge of a chemical plant in Zhejiang Province), so that the total volume of the liquid phase was 50 mL. Then add 4.5 μL of 100 mg·L ^-1 chlorobenzene (Shanghai McLean Biotech, commercially available); then place the sealed bottles in a shaker at 30°C and 160 r·min ^-1 for shaking culture. Take 0.8 mL of the gas in the bottle every 4 to 5 hours, and repeat each group of experiments three times.

The absorbance of the bacteria (OD ₆₀₀ ) was measured at a wavelength of 600 nm using a UV/Vis spectrophotometer (Hitachi High Technologies, Japan), and the dry cell weight of the bacteria was calculated based on the standard curve between the absorbance of the bacteria (OD ₆₀₀ ) and the dry weight of the biomass. In this test, the curve between the bacteria and the dry cell weight (mg·L ^-1 ) was Y=910X-2.8, R ² =0.974.

The changes in chlorobenzene concentration and cell dry weight under different magnetic fields in the shake flask experiment are shown in Figure 10.

From the data analysis and comparison in Figure 10, it can be seen that the heteropolar magnetic field group has completely degraded chlorobenzene within 16 hours, while the homopolar magnetic field group and the blank group need to delay 1 to 3 hours to achieve the same effect. As the reaction time increases, the dry weight of the degrading bacteria cells in the heteropolar magnetic field group increases more, which shows that the degradation effect and microbial content of the heteropolar magnetic field group are higher than those of the other two experimental groups. The reason may be that microorganisms in nature are generally negatively charged; while the magnetic filler of the present invention is positively charged, and the heteropolar magnetic fields will show attraction in this experiment. Under the magnetic force of the magnetic filler, the microorganisms in the system can move continuously along the tangent direction of each point on the magnetic flux line, which increases the dispersion of the microorganisms. In addition, some microbial aggregate particles with higher density are prone to sedimentation due to gravity. The magnetic force of the heteropolar magnetic field can effectively prolong the suspension time of microorganisms in the solution and enhance their activity. Since the homopolar magnetic field will show repulsion, although the microorganisms can also move along the tangent direction of each point on the magnetic flux line, their movement will be affected by the repulsion, the moving distance is limited, and the corresponding dispersion is also low. Since the microorganisms in the blank group are only affected by gravity, their activity is more restricted, which corresponds to the difference in microbial content in the system. In view of this, the present invention magnetizes the magnetic composite filler so that its corresponding magnetic field is synchronously adjusted to a heteropolar magnetic field.

In summary, the reference heteropolar magnetic field is shown in schematic diagram 11-B, and the homopolar magnetic field is shown in schematic diagrams 11-A and 11-C. For magnetic composite fillers, the magnetic field schematic diagram of the porous ball after magnetization is shown in Figure 12, and the magnetic field schematic diagram of the flow sheet on the outer shell after magnetization is shown in Figure 13. Its application in the trickling filter is shown in Experiment 6.

【Test 6】Determination of waste gas degradation rate in trickling filter

The simulated waste gas enters from the bottom of the reactor and is discharged from the top of the reactor. The inlet concentration of chlorobenzene waste gas is maintained at about 200 mg·m ^-3 in terms of chlorobenzene. The pH of the inorganic salt nutrient solution is controlled to be 7.0, the temperature is 30°C, the spraying amount of the nutrient solution is 5~8 L·h ^-1 , and the residence time is 60 s. When it basically reaches stability after 25 days of operation, the corresponding biofilm formation is completed. After the biofilm formation is completed, the concentration of chlorobenzene waste gas increases to 350 mg·m ^-3 . The experiment is divided into a modified group (i.e., inorganic salt culture medium, degradation bacteria seed liquid, composite filler and chlorobenzene) and a modified magnetized group (i.e., inorganic salt culture medium, degradation bacteria seed liquid, magnetic composite filler and chlorobenzene). The composite filler obtained by the preparation method of Comparative Example 9 is added to the reactor of the modified group, and the same amount of magnetic composite filler obtained by the preparation method of Examples 2~10 and Comparative Examples 1~8 is added to the modified magnetized group. Both groups of reactors are operated in a stable state. The reactor was operated continuously, with 500 mL of nutrient solution replaced every 3 days, and the substrate concentrations at the inlet and outlet as well as the parameters required for the experiment were measured every day.

The calculation method of removal efficiency (RE) and empty bed residence time (EBRT) is as follows:

Where, Q is the intake air flow rate, m ³ ·h ^-1 ;

C _in is the inlet chlorobenzene concentration, mg·m ^-3 ;

C _out is the outgassing chlorobenzene concentration, mg·m ^-3 ;

V is the actual working volume of the reactor, m ³ .

The changes in chlorobenzene concentration and chlorobenzene removal rate in the trickling tower are shown in Figure 14.

From the data analysis and comparison in Figure 14, it can be seen that the removal rate of chlorobenzene in the modified magnetized group can reach more than 70.1% after the 24th day of biofilm formation, and this removal performance can be maintained continuously, while the removal rate of the modified group is only 58.7%. When the exhaust gas concentration increases to 350 mg·m ^-3 , the removal rate of the modified magnetized group is basically stable at about 68.8%, while the removal rate of the modified group is maintained at about 52.7%, which also shows that the chlorobenzene removal rate of the modified magnetized group is always higher than that of the modified group. Since the degradation bacteria contain a small amount of paramagnetic metal elements, these metal elements will be rearranged under the action of the static magnetic field, which enhances the activity of the enzymes in the microorganisms and increases their reaction rate; this also further promotes the growth and metabolism of microorganisms, and ultimately accelerates their degradation rate. Since microorganisms in nature generally carry negative charges, they are more easily adsorbed on the surface of the substrate under the static magnetic field of the magnetic composite filler, which also increases the number of microorganisms on the surface of the magnetic composite filler, and the corresponding degradation performance of chlorobenzene exhaust gas is also improved.

In summary, the present invention effectively improves the internal porosity by fixing the outer shell and the porous ball together; with multiple flow holes, the gas flow channels are increased and the pressure loss in the system is significantly reduced. The gas is evenly dispersed in the reactor by designing a uniquely structured biological filler, which further prolongs its residence time and enhances the degradation effect in the biochemical reaction. In addition, by magnetizing the outer shell and the porous ball and then filling the porous filler, a large amount of high-density heteropolar magnetic fields are gathered in the magnetic composite filler, and the contact area with the microorganisms attached to the surface of the porous filler is also greatly increased. Under the action of the heteropolar magnetic field, the unique structure of the filler promotes more microorganisms to have magnetic effects, which further increases the enzyme activity in the microorganisms. The present invention has low production cost, is durable, and is highly efficient and energy-saving, which is conducive to promotion and application in production practice.

The above description is only a detailed description of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, there will be changes in the specific implementation methods based on the ideas provided by the present invention, and these changes should also be regarded as the scope of protection of the present invention.

Claims

A magnetic composite filler, characterized in that it comprises an outer shell (1), wherein a cavity (2) is arranged inside the outer shell (1), and a flow hole (3) connected to the cavity (2) is also arranged on the outer shell (1), a porous ball (4) is arranged in the cavity (2), and a porous filler (5) is filled between the porous ball (4) and the inner wall of the outer shell (1), and the porous ball (4) and the outer shell (1) are magnetic.
A magnetic composite filler according to claim 1, characterized in that the outer shell (1) includes two upper and lower half shells (6), and the half shells (6) are interlocked to form a complete spherical outer shell (1).
A magnetic composite filler according to claim 1 or 2, characterized in that the outer shell (1) is provided with flow sheets (7) arranged radially and staggered, and flow holes (3) connected to the cavity (2) are formed between adjacent flow sheets (7).
A magnetic composite filler according to claim 1, characterized in that two connecting rods (8) for fixing to the outer shell (1) are symmetrically arranged on the outer surface of the porous ball (4), so that the porous ball (4) can be suspended inside the cavity (2) through the connecting rods (8).
A magnetic composite filler according to claim 1, characterized in that the pore size of the porous filler (5) is 0.5~2mm and the porosity is greater than 90%.
A magnetic composite filler according to claim 1, characterized in that the outer shell (1) and the porous ball (4) include the following components, calculated by weight: 60~90 parts of plastic, 2~5 parts of activated carbon, 5~15 parts of magnetic powder, 0.5~4 parts of liquid dispersant, 0.5~3 parts of silane coupling agent, 1~3 parts of starch, 1.5~4 parts of diatomaceous earth, 1~5 parts of hydroxyapatite, and 1~5 parts of polyvinyl alcohol.
A magnetic composite filler according to claim 6, characterized in that the liquid dispersant is one or a combination of white mineral oil and vegetable oil.
A magnetic composite filler according to claim 6 or 7, characterized in that the plastic is a combination of one or more of polyethylene, polypropylene, and acrylonitrile-butadiene-styrene copolymer.
A method for preparing a magnetic composite filler as claimed in any one of claims 1 to 8, characterized in that it comprises the following steps:

(S.1) crushing, sieving and classifying plastic, activated carbon, silane coupling agent, starch, diatomaceous earth, hydroxyapatite and polyvinyl alcohol, heating and drying, and naturally cooling to room temperature to obtain a solid mixed raw material;

(S.2) fully mixing the solid mixed raw material and the liquid dispersant in step (S.1), adding magnetic powder, stirring evenly and granulating to obtain a mixed filler;

(S.3) injection molding the mixed filler in step (S.2), and then magnetizing to obtain the outer shell (1) and the porous ball (4);

(S.4) Assembling and fixing the outer shell (1) and the porous ball (4) obtained in step (S.3) with the porous filler (5) to obtain a hollow ball of magnetic composite filler.
The method for preparing a magnetic composite filler according to claim 9 is characterized in that:

The sieve width used in the step (S.1) is 200-500 mesh, and after sieving, the sieving is dried at 50-90°C for 5-48 hours;

In the step (S.3), the mixed filler is injection molded at 140-180°C, and then placed in a magnetizer of 8000-20000GS for magnetization, so that the outer shell (1) and the porous ball (4) are both provided with a constant magnetic field of 20-100GS;

The porous filler (5) in the step (S.4) is successively cleaned with 5-25% acid and 10-30% alkali to remove impurities and then dried.