Preparation method of modified lignin-based composite filler and circulating fluidized device

Abstract

The application discloses a preparation method and a circulating fluidization device of a modified lignin-based composite filler. The raw material for preparing the modified lignin-based composite filler is composed of wood chips, straw, waste paper, bamboo, corn cob, peanut shell and rice straw. After being subjected to alkylization treatment and esterification treatment respectively, the raw material is mixed with polybutylene succinate, polyurethane and sodium bicarbonate water and granulated. Compared with the prior art, the preparation method improves the carbon release performance of the filler and the utilization efficiency of the solid carbon source, solves the problem of low denitrification efficiency caused by the shortage of carbon source in the denitrification process of sewage treatment, can effectively simplify the preparation process and reduce the processing cost. The circulating fluidization device provided by the application is provided with a sliding cylinder type carbon source chamber for accommodating the spherical solid filler of the above-mentioned filler, and the spherical solid filler is reacted with water by stirring to treat sewage, is suitable for various water environments, and has low equipment cost and is suitable for sewage treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wastewater treatment, in particular to a preparation method of modified lignin-based composite filler and a circulating fluidization device. BACKGROUND

[0002] Biomass is an important zero-carbon raw material and energy. Taking biomass resource utilization as the starting point can effectively promote the synergy of China's carbon peak and carbon neutralization process and environmental pollution control.

[0003] When the C / N value of urban sewage is low, it will lead to high NO 3 -N concentration, poor denitrification effect, large fluctuation of COD and NH 4+ -N concentration, etc. In the traditional wastewater treatment method, liquid carbon sources such as methanol and acetic acid are usually supplemented in the denitrification stage, but the cost is high, and a special dosage control dosing device is needed, so solid slow-release carbon sources such as plant carbon sources are gradually paid attention to. Compared with liquid carbon sources, plant carbon sources are not only easy to obtain, convenient to transport and low in price, but also have the advantages of slow-release ability and can serve as microbial carriers. Although a large amount of soluble organic matter is released by plant carbon sources in the early stage of denitrification, which can meet the demand for carbon sources for denitrification, when the soluble organic carbon source is exhausted, microorganisms will decompose cellulose to obtain supplemental carbon sources. However, lignin forms a structural barrier, reducing the accessibility of enzymes and microorganisms to cellulose and hemicellulose, and thus affecting the denitrification efficiency. Therefore, in order to improve the carbon release performance and utilization efficiency of slow-release carbon sources, lignin needs to be modified.

[0004] Based on the unique physicochemical properties of lignin aromatic structure, surface activity, etc., hot researches are emerging, covering bulk chemicals, fine chemicals and functional materials, etc. However, due to the complex structure, wide molecular weight distribution, low reactivity and other factors, the separation and purification cost is high, the preparation process is complex, which limits its further development in wastewater treatment. SUMMARY

[0005] Therefore, the present application provides a preparation method of modified lignin-based composite filler and a circulating fluidization device to solve the above technical problems.

[0006] A modified lignin-based composite filler, characterized in that the raw materials for preparing the modified lignin-based composite filler consist of 40-50 parts of wood chips, 10-20 parts of straw, 30-40 parts of waste paper, 20-30 parts of bamboo, 30-40 parts of corn cob, 10-15 parts of peanut shell and 20-30 parts of rice straw, and the preparation method comprises the following steps:

[0007] STEP001: providing raw materials for preparing modified lignin-based composite filler for preparing modified lignin-based composite filler;

[0008] STEP002: removing impurities from the straw, bamboo, corn cob, peanut shell and rice straw, washing with deionized water, drying at 40-60°C, grinding and soaking in 10%-15% sodium hydroxide solution at 60-80°C for 6-24h, adding alkylating agent and base catalyst, reaction temperature 80-120°C, reaction time 2-4h;

[0009] STEP003: placing the sawdust and waste paper in a container, mechanically crushing and grinding into powder, adding deionized water at a solid-liquid ratio of 1:60-1:100, placing in an ultrasonic oscillator, ultrasonic treatment at 40-60°C for 30-60min, ultrasonic frequency 40KHz, adding esterification reagent and acid catalyst to the mixed solution, reaction temperature 60-100°C, reaction time 2-6h;

[0010] STEP004: drying the modified mixture flat, drying temperature 40-60°C;

[0011] STEP005: providing raw materials for preparing solid modified carbon source, weight percentage as follows: polybutylene succinate (PBS) 40%-50%, solid modified lignin mixture obtained in step STEP004 50%-60%, polyurethane 0.1%-0.5%, and sodium bicarbonate 0.1%-0.3%;

[0012] STEP006: mixing polybutylene succinate (PBS), solid modified lignin mixture, polyurethane and sodium bicarbonate in step STEP005 with water, and transferring into a granulator, setting the temperature to 120-150°C;

[0013] STEP007: placing the filler obtained in step STEP006 in a spherical shell, filling rate 70%-80%, to obtain a spherical solid filler.

[0014] Further, in the alkylating process, alkyl halide is used as the alkylating agent, and sodium hydroxide or potassium hydroxide is used as the base catalyst.

[0015] Further, in the esterification process, acetic anhydride or propionic anhydride is used as the esterification reagent, and phosphoric acid is used as the acid catalyst.

[0016] Further, the material dried in step STEP002 is cut into 2cm blocks and ground into powder with particle size between 1mm and 3mm for use.

[0017] Further, the fillers obtained by the granulator in step STEP006 are circular or rectangular.

[0018] A circulating fluid device using the modified lignin-based composite filler as described above comprises a suspension filler chamber, a slide cylinder carbon source chamber arranged in the suspension filler chamber, and a microbial carrier chamber arranged on the slide cylinder carbon source chamber. The suspension filler chamber comprises a mounting area arranged in the center of the suspension filler chamber, a filling area arranged adjacent to the mounting area, a plurality of porous filter filler bases arranged at the bottom of the suspension filler chamber, and a plurality of communication holes arranged on the outer wall of the suspension filler chamber. The slide cylinder carbon source chamber comprises a cylinder body, a rotating shaft arranged in the cylinder body, a plurality of stirring rods arranged on the rotating shaft, a feeding hole opened at the top of the cylinder body, a sealing cover arranged on the feeding hole, a lifting handle arranged on one side of the feeding hole, a vent pipe arranged at the bottom of the cylinder body, and the spherical solid filler filled in the cylinder body. The microbial carrier chamber comprises a polyurethane sponge filler filled in the microbial carrier chamber, and a convex clamping groove arranged on the outer wall.

[0019] Further, the suspension filler chamber is a rectangular structure, the slide cylinder carbon source chamber is a cylindrical structure inserted into the suspension filler chamber and coincides with the center of the suspension filler chamber, and the microbial carrier chamber is located between the suspension filler chamber and the slide cylinder carbon source chamber, one side is clamped in the suspension filler chamber, and the other side is tightly attached to the slide cylinder carbon source chamber.

[0020] Further, the mounting area comprises a support ring located at the bottom of the mounting area, and a concave clamping groove located on the side wall of the mounting area. The support ring is a circular clamping groove, the concave clamping groove is arranged on the side wall of the mounting area and the filling area, located on the side close to the mounting area, and the slot direction is the radial direction of the slide cylinder carbon source chamber, and the extension direction of the concave clamping groove is the axial direction of the slide cylinder carbon source chamber.

[0021] Further, the filling area is arranged adjacent to the mounting area and comprises a plurality of movable supports arranged in the filling area, and an inspection cover plate located at the top of the filling area.

[0022] Furthermore, the cylinder body adopts a cylindrical structure, the bottom of the cylinder body is conical, the rotating shaft is located at the axis of the cylinder body, one end of which passes through the top of the cylinder body, the stirring rod is located inside the cylinder body, vertically and fixed on the rotating shaft, the feeding hole is located at the top of the cylinder body, the sealing cap is located on the feeding hole, the vent pipe is located at the bottom of the cylinder body and is provided with a vent valve, and the spherical solid packing adopts a spherical shell.

[0023] Furthermore, the convex groove and the concave groove engage with each other.

[0024] Compared with existing technologies, the preparation method of the modified lignin-based composite filler provided by this invention, compared with other resource utilization methods, utilizes lignin as a novel carbon-releasing material through modification or thermal conversion, improving the carbon release performance and solid carbon source utilization efficiency of the lignin-based composite carbon-releasing filler. This solves the problem of insufficient carbon source leading to low nitrogen removal efficiency in the denitrification process of wastewater treatment, effectively simplifying the preparation process and reducing processing costs. It is a highly promising "waste-to-waste" resource utilization method. The circulating fluidization device provided by this invention, by setting the sliding carbon source chamber, accommodates the spherical solid filler made of modified lignin-based composite carbon-releasing filler. The spherical solid filler reacts with water through stirring for wastewater treatment. It is suitable for various water environments, and the equipment cost is low, making it suitable for wastewater treatment. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a circulating fluidization device provided by the present invention.

[0026] Figure 2 for Figure 1 A cross-sectional schematic diagram of the suspended packing chamber of the circulating fluidization device.

[0027] Figure 3 for Figure 1 A cross-sectional schematic diagram of the sliding carbon source chamber of the circulating fluidization device.

[0028] Figure 4 for Figure 1 A cross-sectional schematic diagram of the microbial carrier chamber in the circulating fluidized bed device.

[0029] Figure 5 for Figure 1 A cross-sectional schematic diagram of the spherical solid packing material in the circulating fluidization device. Detailed Implementation

[0030] The following provides a more detailed description of specific embodiments of the present invention. It should be understood that the description of the embodiments of the present invention herein is not intended to limit the scope of protection of the present invention.

[0031] The application provides a preparation method of a modified lignin-based composite filler, which comprises the following steps:

[0032] STEP001: providing raw materials for preparing a modified lignin solid carbon source, wherein the raw materials are composed of sawdust, straw, waste paper, bamboo, corn cob, peanut shell and straw, and the sawdust accounts for 40-50 parts, the straw accounts for 10-20 parts, the waste paper accounts for 30-40 parts, the bamboo accounts for 20-30 parts, the corn cob accounts for 30-40 parts, the peanut shell accounts for 10-15 parts, and the straw accounts for 20-30 parts;

[0033] STEP002: washing the straw, bamboo, corn cob, peanut shell and straw after simple impurity removal with deionized water, drying at 40-60°C, and then cutting into blocks with a size of about 2 cm and grinding into powder for use, wherein the particle size of the powder is 1-3 mm, and the biomass powder is soaked in a 10%-15% sodium hydroxide aqueous solution for 6-24 h at a heating temperature of 60-80°C, and then a proper amount of an alkylating agent and an alkali catalyst are added to the mixed solution for reaction at a temperature of 80-120°C for 2-4 h;

[0034] STEP003: placing the sawdust and waste paper in a container, mechanically crushing and grinding into powder, adding deionized water at a solid-liquid ratio of 1:60-1:100, placing in an ultrasonic oscillator, and ultrasonic treating for 30-60 min at an ultrasonic frequency of 40 KHz and an ultrasonic temperature of 40-60°C, and then adding a proper amount of an esterification agent and an acid catalyst to the mixed solution for reaction at a temperature of 60-100°C for 2-6 h;

[0035] STEP004: drying the modified mixed solution at a temperature of 40-60°C to obtain a solid modified lignin mixture;

[0036] STEP005: preparing the solid modified carbon source from the following raw materials in percentage by weight: 40%-50% of polybutylene succinate (PBS), 50%-60% of the solid modified lignin mixture in STEP004, 0.1%-0.5% of polyurethane and 0.1%-0.3% of sodium bicarbonate;

[0037] STEP006: mixing the polybutylene succinate (PBS), the solid modified lignin mixture, the polyurethane and the sodium bicarbonate in STEP005 with water, and then feeding into a granulator and setting the temperature to 120-150°C to obtain round or rectangular fillers;

[0038] STEP007: Put the circular or rectangular filler described in step STEP006 into the spherical shell, and fill it to 70%-80% to obtain a spherical solid filler.

[0039] In step STEP001, sawdust, straw, waste paper, bamboo, corn cob, peanut shells, and rice straw are used as raw materials. On the one hand, it can reduce the burden on the ecological environment, and on the other hand, it can utilize waste, which is conducive to sustainable development. Studies have shown that the lignin content of rice straw is more than 25%, the lignin content of peanut shells is more than 30%, the lignin content of corn cob is more than 15%, the lignin content of rice straw is more than 15%, the lignin content of sawdust is about 20%-35%, the lignin content of waste paper varies greatly, ranging from 11% to 35%, and the lignin content of bamboo is between 16 and 34%. The determination of the number of materials needs to consider the lignin content, the efficiency of alkylation and esterification, the content of waste in nature or different environments, the amount of residue after treatment, and the treatment. The proportion of the number of materials can be changed. In order to solve the problem of waste treatment in nature, multiple waste materials can be used for treatment.

[0040] In step STEP002, the laboratory uses a constant temperature drying oven to dry. The commonly used drying temperature is 40℃-60℃. The choice of drying temperature depends on the type and characteristics of the material to be dried, the type and setting of the dryer, and safety factors. Drying at 40℃-60℃, preferably in a working environment of 50℃, can achieve higher drying efficiency while not changing the properties of the material due to excessive temperature.

[0041] When grinding, the particles are ground to between 1mm and 3mm to react more efficiently with the reagents. When alkylating the solution, alkyl halides or other reagents are used as alkylating agents, and sodium hydroxide, potassium hydroxide, etc. are used as alkali catalysts. Alkylation is a reaction process that introduces alkyl groups into organic molecules by addition or displacement reaction, which is a widely used existing technology in chemical production and should be well known to those skilled in the art. Therefore, only a brief description is given here. The amount of reagent should be sufficient to allow most of the active sites in lignin to undergo alkylation. The temperature is controlled at 60℃-100℃, preferably 70℃. The reaction time is 2h-6h, preferably 4.5h. Experiments have shown that a temperature of 70℃ and a reaction time of 4.5h can better initiate the reaction with less byproduct production.

[0042] In step STEP003, the ionic impurities in the material can be effectively removed by using deionized water. The solution is subjected to ultrasonic treatment for 30-60 minutes by using an ultrasonic oscillator. Ultrasonic oscillation refers to the use of high-frequency sound waves of ultrasonic waves to generate oscillation, which is used for extraction, stirring, cleaning of utensils, etc. With its unique advantages of low extraction temperature, high extraction rate and short extraction time, it is applied to the extraction of effective content of traditional Chinese medicinal materials and various animals and plants by innovative people, which is a modern high-tech means to replace the traditional shearing process to realize efficient, energy-saving and environmentally friendly extraction.

[0043] When the solution is subjected to esterification treatment, acetic acid, acetone anhydride and other reagents are used as esterification agents, and phosphoric acid and other reagents are used as acid catalysts. Esterification treatment is a prior art widely used in chemical production field, which should be well known to those skilled in the art. Therefore, only a brief description is given here. The amount of esterification reagent should be sufficient to cause most of the hydroxyl functional groups to undergo esterification reaction. The temperature is controlled at 60-100°C, preferably 70°C. The reaction time is 2-6 hours, preferably 4.5 hours. Experiments have proved that the temperature is 70°C and the reaction time is 4.5 hours, which can better initiate the reaction and produce less by-products.

[0044] In step STEP004, drying is carried out at 40-60°C, preferably in a working environment of 50°C, so as to obtain higher drying efficiency without changing the properties of the material due to too high temperature.

[0045] In step STEP006, a granulator is used to make the mixed solution into rectangular or circular solid fillers. The granulator is a prior art, which should be well known to those skilled in the art. Therefore, its functions will not be described in detail here. The temperature of the granulator is set at 120-150°C to obtain higher granulation efficiency.

[0046] In step STEP007, spherical shells are used to make the fillers have better fluidization state during use and smaller friction between the shells. The material of the shell is generally PVC to obtain corrosion resistance.

[0047] As shown in Figures 1 to 5 The circulating fluidization device provided by the present application is shown in the structure schematic view. The circulating fluidization device comprises a suspension filler chamber 10, a sliding cylinder type carbon source chamber 20 arranged in the suspension filler chamber 10, and a microorganism carrier chamber 30 arranged on the sliding cylinder type carbon source chamber 20. It is conceivable that the circulating fluidization device further comprises other functional modules such as photovoltaic cell panel, electrical cabinet, aeration fan, etc., which are well known to those skilled in the art and will not be described here.

[0048] The suspension filler chamber 10 is a rectangular structure, the sliding cylinder type carbon source chamber 20 is a cylindrical structure inserted in the suspension filler chamber 10 and coincides with the center of the suspension filler chamber 10, and the microbial carrier chamber 30 is located between the suspension filler chamber 10 and the sliding cylinder type carbon source chamber 20, one side is clamped in the suspension filler chamber 10, and the other side is close to the sliding cylinder type carbon source chamber 20.

[0049] The suspension filler chamber 10 includes a mounting area 11 arranged in the center of the suspension filler chamber 10, a filling area 12 arranged adjacent to the mounting area 11, a plurality of porous filter filler bases 13 arranged at the bottom of the suspension filler chamber 10, and a plurality of communication holes 14 arranged on the outer wall of the suspension filler chamber 10.

[0050] The mounting area 11 is a rectangular space located at the center of the suspension filler chamber 10, used for mounting the microbial carrier chamber 30, and includes a support ring 111 located at the bottom of the mounting area 11 and a concave clamping groove 112 located on the side wall of the mounting area 11. The support ring 111 is a circular clamping groove for inserting the sliding cylinder type carbon source chamber 20. The concave clamping groove 112 is arranged on the side wall of the mounting area 11 and the filling area 12, located close to the mounting area 11, and the slot direction is the radial direction of the sliding cylinder type carbon source chamber 20. The extension direction of the concave clamping groove 112 is the axial direction of the sliding cylinder type carbon source chamber 20, for inserting and clamping the microbial carrier chamber 30.

[0051] The filling area 12 is arranged adjacent to the mounting area 11 and includes a plurality of movable supports 121 arranged in the filling area 12 and an inspection cover plate 122 located at the top of the filling area 12. The movable support 121 can be a grid-like frame structure fixed in the filling area 12 by buckles or hooks and the like, for accommodating and filling the suspension filler, which is a common technology in sewage treatment technology and should be well known to those skilled in the art, so only a brief description is given here. The inspection cover plate 122 is arranged at the top of the filling area 12 away from the porous filter filler base 13, and can be fixed by hinges and latches to facilitate replacement of the suspension filler.

[0052] The porous filter filler base 13 is arranged at the bottom of the suspension filler chamber 10, provides the required air to the suspension filler chamber 10 through aeration, and has an average pore size of 1mm-3mm, to prevent spherical solid fillers from running out of the device under the action of external force such as hydraulic impact of a circulating pump or a backflow pump, and has a filtering function.

[0053] The communication hole 14 is arranged on the outer side wall of the hanging filler chamber 10 away from the microbial carrier chamber 30, for communicating the inside and outside of the hanging filler chamber 10.

[0054] The sliding cylinder type carbon source chamber 20 comprises a cylinder body 21, a rotating shaft 22 arranged in the cylinder body 21, a plurality of stirring rods 23 arranged on the rotating shaft 22, a feeding hole 24 arranged on the top of the cylinder body 21, a sealing cover 25 arranged on the feeding hole 24, a pull handle 26 arranged on one side of the feeding hole 24, a vent pipe 27 arranged at the bottom of the cylinder body 21, and a spherical solid filler 28 filled in the cylinder body 21.

[0055] The cylinder body 21 adopts a cylindrical structure for accommodating the spherical solid filler 28 and reacting with sewage. The bottom of the cylinder body 21 is conical to facilitate the discharge and replacement of the filler. The rotating shaft 22 is arranged at the center axis of the cylinder body 21, and one end penetrates the top of the cylinder body 21. When the water flow enters from the top of the cylinder body 21, under the action of the water pump, the water flow impacts on the rotating shaft 22 and the stirring rods 23, driving the rotating shaft 22 and the stirring rods 23 to rotate. The stirring rods 23 are located in the cylinder body 21, perpendicular to and fixed on the rotating shaft 22, so as to agitate the spherical solid filler 28 filled in the cylinder body 21 when the rotating shaft 22 rotates, so that the reaction is more sufficient. The feeding hole 24 is arranged on the top of the cylinder body 21 for adding the spherical solid filler 28. The sealing cover 25 is arranged on the feeding hole 24, which is opened when filling the filler and closed at other times. The pull handle 26 is arranged on the top of the cylinder body 21 for pulling out the sliding cylinder type carbon source chamber 20 from the microbial carrier chamber 30 for replacement and daily maintenance of the filler. The vent pipe 27 is arranged at the bottom of the cylinder body 21 and is provided with a vent valve 271 for discharging the spherical solid filler 28 in the cylinder body 21, and correspondingly, the vent pipe 27 is normally closed. The spherical solid filler 28 is the filler prepared by the above method, which adopts a spherical shell, so that the fluidization state of the filler is better during use, and the friction between the shells is smaller.

[0056] The microbial carrier chamber 30 is a rectangular structure, which is arranged close to the hanging filler chamber 10 at the center axis, and comprises a polyurethane sponge filler 31 filled in the microbial carrier chamber 30, and a convex clamping groove 32 arranged on the outer wall.

[0057] The polyurethane sponge filler 31 has the characteristics of rich porosity as a biofilm carrier for sewage treatment, and the porous three-dimensional network cubic structure makes it easier for microorganisms to attach and form biofilm, and has the advantages of fast biofilm removal, less sludge production, and can effectively improve the sewage treatment capacity of the filler. The convex clamping groove 32 and the concave clamping groove 112 are mutually buckled, so that the microbial carrier chamber 30 is more stable with the hanging filler chamber 10 and will not shake or displace. Specific embodiments

[0059] The solid carbon source includes the following components: 40 parts of sawdust, 10 parts of straw, 40 parts of waste paper, 30 parts of bamboo, 30 parts of corn cob, 10 parts of peanut shell, and 20 parts of straw.

[0060] The above-mentioned straw, bamboo, corn cob, peanut shell, and straw are simply cleaned of impurities, washed with deionized water, dried at 60°C, then cut into blocks of about 2 cm, ground into powder, and used. The particle size of the powder is between 1-3 mm. The ground biomass powder is soaked in a 3% sodium hydroxide solution for 6 hours, with the temperature being 60°C. An appropriate amount of alkylating agent (such as alkyl halide) and base catalyst (such as sodium hydroxide and potassium hydroxide) is added to the mixed solution. The amount of reagent should be sufficient to cause most of the active sites in lignin to undergo alkylation. The reaction temperature is 100°C and the reaction time is 4 hours.

[0061] The above-mentioned sawdust and waste paper are placed in a container, mechanically broken and ground into powder, then deionized water is added at a solid-liquid ratio of 1:100, placed in an ultrasonic oscillator, ultrasonic treatment for 30 min, ultrasonic frequency 40KHz, ultrasonic temperature 40°C, and an appropriate amount of esterification reagent (such as acetic anhydride and propionic anhydride) and acid catalyst (phosphoric acid) is added to the mixed solution. The amount of esterification reagent should be sufficient to cause most of the hydroxyl functional groups to undergo esterification. The reaction temperature is 100°C and the reaction time is 6 hours.

[0062] The modified mixed solution is spread and dried at a temperature of 60°C to obtain a solid modified lignin mixture.

[0063] The solid modified carbon source is made from the following raw materials by weight percentage: polybutylene succinate (PBS) 40%, solid modified lignin mixture 59%, polyurethane 0.5%, and sodium bicarbonate 0.3%. The above-mentioned raw materials are added with water and transferred into a granulator at a temperature of 120°C to obtain a rectangular carbon source filler 281.

[0064] The rectangular carbon source filler 281 is placed in a spherical shell with a filling rate of 80% to obtain a spherical solid filler 28.

[0065] Example One: The filling rate of the rectangular carbon source filler in the spherical shell is 80%, the filling rate of the spherical solid filler in the barrel 21 is 70%, the filling rate of the suspended filler in the filling area 12 is 60%, the aeration concentration is 2 mg / L-4 mg / L, the pH is 6.5-8.5, the environmental temperature is 25℃-30℃, the nitrate nitrogen concentration is 40 mg / L, the nitrite nitrogen is 0, the COD concentration is 100 mg / L, the treatment time is 14 d, the final nitrate nitrogen concentration is 0.36 mg / L, and the denitrification rate reaches 99.1%. If the filling rate of the spherical solid filler is 0, that is, no carbon source is added, the denitrification rate reaches 64%.

[0066] Example Two The filling rate of the rectangular carbon source filler is 80%, the filling rate of the spherical solid filler is 80%, the filling rate of the suspended filler is 70%, the aeration concentration is 2 mg / L-4 mg / L, the pH is 6.5-8.5, the environmental temperature is 25℃-30℃, the nitrate nitrogen concentration is 50 mg / L, the nitrite nitrogen is 0, the COD concentration is 100 mg / L, the treatment time is 14 d, the final nitrate nitrogen concentration is 0.35 mg / L, and the denitrification rate reaches 99.3%. If the filling rate of the spherical solid filler is 0, that is, no carbon source is added, the denitrification rate reaches 68%.

[0067] Example Three The filling rate of the rectangular carbon source filler is 70%, the filling rate of the spherical solid filler is 70%, the filling rate of the suspended filler is 70%, the aeration concentration is 2 mg / L-4 mg / L, the pH is 6.5-8.5, the environmental temperature is 25℃-30℃, the nitrate nitrogen concentration is 10 mg / L, the nitrite nitrogen is 0, the COD concentration is 60 mg / L, the treatment time is 14 d, the final nitrate nitrogen concentration is 0.02 mg / L, and the denitrification rate reaches 99.8%. If the filling rate of the spherical solid filler is 0, that is, no carbon source is added, the denitrification rate reaches 71%.

[0068] In sewage treatment, the higher the denitrification rate, the better the sewage treatment effect. As can be seen from the denitrification rates of the three embodiments using the spherical solid filler 28 and not using the spherical solid filler 28, when the spherical solid filler 28 is used, the denitrification rate of sewage treatment can be significantly improved. At the same time, according to the different filling rates used in the above three embodiments, it can be seen that under the same environment, the rectangular carbon source filler has a better effect when the filling rate is 80%, the spherical solid filler has a better effect when the filling rate is 70%, and the suspended filler has a better effect when the filling rate is 70%.

[0069] Compared with the prior art, the preparation method of the modified lignin-based composite filler provided by the application uses lignin as a new carbon release material resource through modification or thermal conversion, improves the carbon release performance of the lignin-based composite carbon release filler and the utilization efficiency of the solid carbon source, solves the problem of low denitrification efficiency caused by insufficient carbon source in the denitrification process of wastewater treatment, can effectively simplify the preparation process and reduce the processing cost, is a very potential "waste-to-waste" resource utilization method, and the circulating fluidization device provided by the application is used for accommodating the spherical solid filler 28 of the composite carbon release filler made of modified lignin-based, and the spherical solid filler 28 is reacted with water through stirring to treat wastewater, is suitable for various water environments, and has low equipment cost and is suitable for wastewater treatment.

[0070] The above is only a preferred embodiment of the application and is not used to limit the protection scope of the application, and any modification, equivalent replacement or improvement within the spirit of the application is covered within the protection scope of the application.

Claims

1. A modified lignin-based composite filler, characterized in that: The raw materials for preparing the modified lignin-based composite filler consist of the following components per 100 parts: 40-50 parts sawdust, 10-20 parts straw, 30-40 parts waste paper, 20-30 parts bamboo, 30-40 parts corn cob, 10-15 parts peanut shell, and 20-30 parts rice straw. The preparation method includes the following steps: STEP001: Provides raw materials for preparing modified lignin-based composite fillers; STEP002: After removing impurities from the straw, bamboo, corn cob, peanut shell and rice straw, wash them with deionized water, dry them at 40℃-60℃, grind them and soak them in a 10%-15% sodium hydroxide aqueous solution at a heating temperature of 60℃-80℃ for 6h-24h. Add alkylation reagent and alkaline catalyst, react at 80℃-120℃ for 2h-4h. STEP003: Place the wood chips and waste paper in a container, mechanically crush and grind them into powder, then add deionized water at a solid-liquid ratio of 1:60-1:100, place the mixture in an ultrasonic oscillator, and ultrasonically treat it at a temperature of 40℃-60℃ for 30-60 minutes at an ultrasonic frequency of 40KHz. Add esterification reagent and acid catalyst to the mixed solution, and react at a temperature of 60℃-100℃ for 2-6 hours. STEP004: Spread the modified mixture evenly and dry it at a temperature of 40-60℃; STEP005: Provide raw materials for preparing solid modified carbon sources, in the following weight percentages: polybutylene succinate (PBS) 40%–50%, solid modified lignin mixture obtained in step STEP004 50%–60%, polyurethane 0.1%–0.5%, and sodium bicarbonate 0.1%–0.3%; STEP006: Mix the polybutylene succinate (PBS), solid modified lignin mixture, polyurethane and sodium bicarbonate described in step STEP005 with water, and transfer the mixture into a granulator, setting the temperature to 120℃-150℃. STEP007: Place the packing material obtained in step STEP006 into a spherical shell with a filling rate of 70%-80% to obtain spherical solid packing material.

2. The modified lignin-based composite filler as described in claim 1, characterized in that: In the alkylation process, alkyl halides are used as alkylating agents, and sodium hydroxide or potassium hydroxide is used as a base catalyst.

3. The modified lignin-based composite filler as described in claim 1, characterized in that: During esterification, acetic anhydride or pyruvate anhydride is used as the esterification reagent, and phosphoric acid is used as the acid catalyst.

4. The modified lignin-based composite filler as described in claim 1, characterized in that: After drying in step STEP002, the material is chopped into 2cm blocks and ground into powder with a particle size between 1mm and 3mm for later use.

5. The modified lignin-based composite filler as described in claim 1, characterized in that: In step STEP006, the filler obtained by the granulation mechanism is circular or rectangular.

6. A circulating fluidization device using the modified lignin-based composite packing as described in any one of claims 1 to 5, characterized in that: The circulating fluidization device includes a suspended packing chamber, a sliding carbon source chamber disposed within the suspended packing chamber, and a microbial carrier chamber disposed on the sliding carbon source chamber. The suspended packing chamber includes an installation area disposed in the center of the suspended packing chamber, a filling area disposed adjacent to the installation area, multiple porous filter packing bases disposed at the bottom of the suspended packing chamber, and multiple connecting holes disposed on the outer wall of the suspended packing chamber. The sliding carbon source chamber includes a cylinder body, a rotating shaft disposed within the cylinder body, multiple stirring rods disposed on the rotating shaft, a feeding hole opened at the top of the cylinder body, a sealing cap disposed on the feeding hole, a lifting handle disposed on one side of the feeding hole, a vent pipe disposed at the bottom of the cylinder body, and a spherical solid packing material filled within the cylinder body. The microbial carrier chamber includes a polyurethane sponge packing material filled within the microbial carrier chamber, and a convex groove disposed on the outer wall.

7. The circulating fluidization apparatus as described in claim 6, characterized in that: The suspended packing chamber is a rectangular structure, and the sliding carbon source chamber is a cylindrical structure inserted into the suspended packing chamber and coincides with the center of the suspended packing chamber. The microbial carrier chamber is located between the suspended packing chamber and the sliding carbon source chamber, with one side snapped into the suspended packing chamber and the other side in close contact with the sliding carbon source chamber.

8. The circulating fluidization apparatus as described in claim 6, characterized in that: The installation area includes a support ring at the bottom of the installation area and a concave groove on the side wall of the installation area. The support ring is a circular snap-fit ​​groove. The concave groove is disposed on the side wall of the installation area and the filling area, and is located on the side closer to the installation area. The groove is radially oriented towards the sliding carbon source chamber, and extends axially towards the sliding carbon source chamber.

9. The circulating fluidization apparatus as described in claim 8, characterized in that: The filling area is located adjacent to the installation area and includes multiple movable brackets disposed within the filling area, as well as an inspection cover plate located on top of the filling area.

10. The circulating fluidization apparatus as described in claim 6, characterized in that: The cylinder body adopts a cylindrical structure with a conical bottom. The rotating shaft is located at the center of the cylinder body, with one end passing through the top of the cylinder body. The stirring rod is located inside the cylinder body, vertically fixed to the rotating shaft. The feeding hole is located at the top of the cylinder body, and the sealing cap is located on the feeding hole. The vent pipe is located at the bottom of the cylinder body and is equipped with a vent valve. The spherical solid packing adopts a spherical shell.

11. The circulating fluidization apparatus as described in claim 8, characterized in that: The convex groove and the concave groove engage with each other.

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