Sludge bio-drying honeycomb oxygen storage conditioner and preparation method thereof

Abstract

The application discloses a sludge biological drying honeycomb oxygen storage conditioner and a preparation method thereof, relates to the technical field of sludge resource utilization, and provides the honeycomb oxygen storage conditioner preparation method which utilizes biomass and cerium-zirconium solid solution co-pyrolysis, combines porous biochar and oxygen storage materials, utilizes the porous characteristics of the biochar to expand the contact area of the oxygen storage materials and the heap environment, increases the sludge biological drying heap void, makes the oxygen storage materials better release oxygen in the oxygen-poor environment, makes the microorganisms obtain more oxygen, effectively improves the oxygen utilization of the microorganisms in sludge biological drying, realizes the regulation and control of sludge biological drying, and improves the efficiency of sludge biological drying.

Description

Technical fields:

[0001] This invention relates to the field of sludge resource utilization technology, specifically to a sludge biological drying honeycomb oxygen storage conditioner and its preparation method. Background technology:

[0002] Sludge biological drying technology utilizes the bioheat generated by the aerobic respiration of microorganisms in sludge to degrade organic matter, combined with forced ventilation to promote moisture evaporation, to rapidly and effectively dry sludge without adding external heat energy. The drying process results in minimal loss of organic matter and calorific value, and offers advantages such as low energy consumption, stable equipment operation, and flexible product applications.

[0003] However, current sludge biological drying technology still faces bottlenecks such as low microbial oxygen utilization and short duration of high-temperature zones, resulting in long processing times and large land requirements, thus hindering its widespread application. In sludge biological drying systems, microorganisms utilize oxygen for metabolism. As microorganisms multiply rapidly, the oxygen concentration decreases, making it difficult to maintain system heat by increasing aeration.

[0004] Cerium oxide (CeO2) belongs to the cubic crystal system with a fluorite-type crystal structure, where the interstitial spaces of its octahedrons are empty. Cerium ions in cerium oxide exist in both +3 and +4 valence states, and can transition between these two states under different oxygen environments (oxygen-rich and oxygen-poor). Because cerium oxide itself can perform these two valence state transitions, it can store and release oxygen while maintaining its fluorite-type structure. Compared to pure cerium oxide, cerium-zirconium solid solution (CeO2) exhibits superior oxidation state properties. X Zr 1-X O2 has higher thermal stability and oxygen storage capacity. The introduction of zirconium oxide causes lattice structure defects, increases the concentration of oxygen holes, lowers the activation energy of bulk oxygen, and promotes the diffusion of bulk oxygen, thereby increasing the reaction rate and oxygen storage and release capacity.

[0005] A honeycomb oxygen-storing conditioner prepared from biomass combined with cerium-zirconium solid solution can significantly increase oxygen exchange in biological drying systems, and partially enhance oxygenation during aeration. 3+ Oxidized to Ce 4+ Oxygen enters the honeycomb oxygen conditioning agent to store oxygen. In oxygen-deficient conditions, Ce... 4+ Reduced to Ce 3+ Meanwhile, O 2- The loss of electrons and the release of oxygen from the cerium oxide lattice increase the oxygen concentration in the system, which is beneficial for microbial respiration, metabolism, and heat production. Summary of the Invention:

[0006] To overcome the shortcomings of existing technologies, this invention provides a method for preparing a honeycomb oxygen storage conditioner for sludge biological drying. The resulting honeycomb oxygen storage conditioner has the characteristics of storing and releasing oxygen. By utilizing the transformation of cerium oxide between different valence states under different oxygen environments, it increases the oxygen utilization rate of microorganisms and achieves regulation of sludge biological drying. Furthermore, by utilizing the honeycomb structure and the rich porosity of biochar obtained from biomass pyrolysis, it further expands the oxygen-rich microenvironment and provides a good growth environment for microorganisms.

[0007] The technical problem to be solved by this invention is achieved by the following technical solution:

[0008] The first objective of this invention is to provide a method for preparing a honeycomb oxygen conditioning agent, comprising the following steps:

[0009] (1) Mix biomass thoroughly with cerium salt and zirconium salt, soak in alkaline solution, add binder, mix evenly, and obtain precursor;

[0010] (2) The precursor is pressed into shape, dried, and pyrolyzed to obtain a honeycomb oxygen storage conditioner.

[0011] Preferably, the preparation method of the precursor is as follows: take biomass, dry it to constant weight, grind it evenly, mix it thoroughly with cerium salt and zirconium salt, soak it in alkaline solution, filter it, and then add a binder and mix it evenly to obtain the precursor.

[0012] Preferably, the biomass is selected from at least one of agricultural waste such as corn cobs, straw, rice husks, and peanut shells.

[0013] Preferably, the biomass is dried and ground evenly before use, so as to ensure that the biomass is in full contact with cerium salts and zirconium salts.

[0014] Preferably, the cerium salt is at least one of the commonly used inorganic cerium salts in the art, such as cerium nitrate, cerium sulfate, cerium chloride, and cerium hydroxide.

[0015] Preferably, the zirconium salt is at least one of the commonly used inorganic zirconium salts in the art, such as zirconium nitrate, zirconium oxynitrate, zirconium sulfate, and zirconium chloride.

[0016] Preferably, the weight ratio of the biomass to cerium salt and zirconium salt is (10-50):(1-5):(1-5).

[0017] Preferably, the alkaline solution is at least one of commonly used alkaline solutions in the art, such as ammonia water, sodium hydroxide solution, sodium carbonate solution, and ammonium carbonate solution.

[0018] Preferably, the soaking time in the alkaline solution is 0.5 to 4 hours.

[0019] Preferably, the binder is at least one of commonly used binders in the art, such as plant starch and coal tar. More preferably, the plant starch includes, but is not limited to, corn starch, sweet potato starch, potato starch, wheat starch, mung bean starch, and pea starch.

[0020] Preferably, the weight ratio of biomass to binder is 20:(1-5). The amount of binder is appropriately controlled while ensuring the precursor is properly compressed and molded.

[0021] Preferably, the compression molding involves placing the precursor in a honeycomb mold of suitable size, extruding it, and then drying it.

[0022] Preferably, the shape of the pressed form includes, but is not limited to, cubes, cuboids, spheres, cylinders, prisms, etc. The shape of the precursor pressed form can be selected according to actual needs.

[0023] Preferably, the aperture of the honeycomb mold is 0.5 to 5 mm, and the size is not required.

[0024] Preferably, the pyrolysis is carried out in a nitrogen atmosphere, with a heating rate of 10–30 °C / min, a pyrolysis temperature of 300–700 °C, and a pyrolysis time of 2.5–5 h.

[0025] A second objective of this invention is to provide a honeycomb oxygen storage conditioner prepared according to the aforementioned method. The aforementioned method combines porous biochar with an oxygen storage material, enabling the oxygen storage material to better release oxygen in oxygen-deficient environments.

[0026] A third objective of this invention is to provide the application of the aforementioned honeycomb oxygen-storing conditioner in sludge bio-drying. By applying the honeycomb oxygen-storing conditioner obtained through the aforementioned preparation method to sludge bio-drying, the oxygen utilization of microorganisms during sludge bio-drying is improved, thereby achieving regulation of sludge bio-drying.

[0027] The beneficial effects of this invention are:

[0028] 1. The method for preparing the honeycomb oxygen storage conditioner provided by the present invention can use agricultural waste such as corn cobs, straw, rice husks, and peanut shells as raw materials, which is inexpensive and realizes the reuse of agricultural waste resources.

[0029] 2. The method for preparing the honeycomb oxygen storage conditioner provided by the present invention utilizes the co-pyrolysis of biomass and cerium-zirconium solid solution to combine porous biochar with oxygen storage material. The porous characteristics of biochar are used to expand the contact area between the oxygen storage material and the pile environment, and increase the porosity of the sludge biological drying pile, so that the oxygen storage material can better release oxygen in the oxygen-deficient environment and allow microorganisms to obtain more oxygen.

[0030] 3. The honeycomb oxygen storage conditioner provided by the present invention further increases the pore size by utilizing the honeycomb structure. The honeycomb structure also makes the combination of biochar and cerium zirconium solid solution more stable. The independent structure can be recycled and reused after the biological drying is completed, saving conditioner and reducing costs.

[0031] 4. The honeycomb oxygen storage conditioner provided by this invention effectively improves the oxygen utilization of microorganisms in sludge biological drying, realizes the regulation of sludge biological drying, and improves the efficiency of sludge biological drying. Detailed implementation method:

[0032] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0033] Example 1

[0034] Rice husks were dried in a 105℃ oven, weighed repeatedly until a constant weight was achieved, and then ground into a uniform powder for later use. 10g of dried rice husks, 0.7g of cerium nitrate, and 0.3g of zirconium nitrate were weighed and thoroughly mixed. The mixture was then soaked in 15% ammonia solution for 60 minutes, filtered, and corn starch was added and mixed thoroughly to obtain the precursor. The precursor was placed in a honeycomb mold with dimensions of 50*50*100mm and a pore spacing of 1.55mm, extruded, and dried until the moisture content was below 2%. The dried precursor was then placed in a pyrolysis furnace under a nitrogen atmosphere, with a heating rate of 10℃ / min, a pyrolysis temperature of 400℃, and a pyrolysis time of 2.5h to obtain the honeycomb oxygen storage conditioner.

[0035] The specific surface area of ​​the honeycomb oxygen storage conditioner prepared in this embodiment was measured to be 69.48 m² using a specific surface area and pore size analyzer and a fully automated chemisorption analyzer, respectively. 2 The oxygen storage capacity is 219 μmol O2 / g. This indicates that the honeycomb oxygen storage conditioner prepared in this embodiment has good oxygen storage capacity.

[0036] Example 2

[0037] Rice husks were dried in a 105℃ oven, weighed repeatedly until a constant weight was achieved, and then ground into a uniform powder for later use. 10g of dried rice husks, 0.7g of cerium nitrate, and 0.3g of zirconium nitrate were weighed and thoroughly mixed. The mixture was then soaked in 15% ammonia solution for 60 minutes, filtered, and corn starch was added and mixed thoroughly to obtain the precursor. The precursor was placed in a honeycomb mold with dimensions of 50×50×100mm and a pore spacing of 1.55mm, extruded, and dried until the moisture content was below 2%. The dried precursor was then placed in a pyrolysis furnace under a nitrogen atmosphere, with a heating rate of 10℃ / min, a pyrolysis temperature of 600℃, and a pyrolysis time of 2.5h to obtain the honeycomb oxygen storage conditioner.

[0038] The specific surface area of ​​the honeycomb oxygen storage conditioner prepared in this embodiment was determined to be 77.21 m² using a specific surface area and pore size analyzer and a fully automated chemisorption analyzer, respectively. 2 The oxygen storage capacity is 281 μmol O2 / g. This indicates that the honeycomb oxygen storage conditioner prepared in this embodiment has good oxygen storage capacity, and its performance can be adjusted by changing the pyrolysis conditions.

[0039] Comparative Example 1

[0040] Rice husks were dried in a 105℃ oven, weighed repeatedly until a constant weight was achieved, and then ground into a uniform powder for later use. 10g of dried rice husks, 0.7g of cerium nitrate, and 0.3g of zirconium nitrate were weighed and thoroughly mixed. The mixture was then soaked in 15% ammonia solution for 60 minutes, filtered, and corn starch was added and mixed thoroughly to obtain the precursor. The precursor was placed in a honeycomb mold with dimensions of 50×50×100mm and a pore spacing of 1.55mm, extruded, and dried until the moisture content was below 2%. The dried precursor was then placed in a pyrolysis furnace under a nitrogen atmosphere, with a heating rate of 10℃ / min, a pyrolysis temperature of 1000℃, and a pyrolysis time of 2.5h to obtain the honeycomb oxygen storage conditioner.

[0041] The specific surface area of ​​the honeycomb oxygen storage conditioner prepared in this comparative example was determined to be 26.52 m² using a specific surface area and pore size analyzer and a fully automated chemisorption analyzer, respectively. 2 The oxygen storage capacity is 176 μmol O2 / g. This indicates that if the pyrolysis temperature is too high, the surface pores of the prepared honeycomb oxygen storage conditioner collapse, the specific surface area decreases, and the oxygen storage capacity decreases.

[0042] Comparative Example 2

[0043] Rice husks were dried in an oven at 105℃, weighed repeatedly until a constant weight was achieved, and then ground into a uniform powder for later use. 10g of dried rice husks and 1g of cerium nitrate were weighed and thoroughly mixed, then corn starch was added and mixed evenly to obtain a precursor. The precursor was placed in a honeycomb mold with dimensions of 50×50×100mm and a hole spacing of 1.55mm, extruded, and dried until the moisture content was below 2%. The dried precursor was then placed in a pyrolysis furnace with a nitrogen atmosphere, a heating rate of 10℃ / min, a pyrolysis temperature of 600℃, and a pyrolysis time of 2.5h to obtain a honeycomb oxygen storage conditioner.

[0044] The specific surface area of ​​the honeycomb oxygen storage conditioner prepared in this comparative example was determined to be 46.17 m² using a specific surface area and pore size analyzer and a fully automated chemisorption analyzer, respectively. 2 / g, with an oxygen storage capacity of 90μmol O2 / g. This indicates that without zirconium nitrate doping, the oxygen storage capacity of the prepared honeycomb oxygen storage conditioner is significantly reduced, because cerium-zirconium solid solution has higher thermal stability and oxygen storage capacity.

[0045] Comparative Example 3

[0046] Mix 0.7g of cerium nitrate and 0.3g of zirconium nitrate thoroughly, soak in 15% ammonia solution for 60 minutes, filter, add 10g of boehmite (an inorganic binder added to ensure the final size matches the example), and mix thoroughly to obtain the precursor. Place the precursor in a honeycomb mold with dimensions of 50×50×100mm and a pore spacing of 1.55mm, extrude to form, and dry until the moisture content is below 2%. Take the dried precursor and set the pyrolysis furnace to a nitrogen atmosphere, a heating rate of 10℃ / min, a pyrolysis temperature of 400℃, and a pyrolysis time of 2.5h to obtain the honeycomb oxygen storage conditioner.

[0047] The specific surface area of ​​the honeycomb oxygen storage conditioner prepared in this embodiment was determined to be 11.84 m² using a specific surface area and pore size analyzer and a fully automated chemisorption analyzer, respectively. 2 / g, with an oxygen storage capacity of 127 μmol O2 / g. Replacing biomass with inorganic binders significantly reduces the specific surface area and oxygen storage capacity of the conditioner. However, biomass pyrolysis allows some organic matter to volatilize, effectively increasing the specific surface area of ​​the conditioner and the contact area between the cerium-zirconium solid solution and air.

[0048] Comparative Example 4

[0049] Rice husks were dried in a 105℃ oven, weighed repeatedly until a constant weight was achieved, and then ground into a uniform powder for later use. 11g of dried rice husks were weighed, soaked in 15% ammonia solution for 60 minutes, filtered, and then mixed with corn starch to obtain a precursor. The precursor was placed in a honeycomb mold with dimensions of 50*50*100mm and a pore spacing of 1.55mm, extruded, and dried until the moisture content was below 2%. The dried precursor was then placed in a pyrolysis furnace with a nitrogen atmosphere, a heating rate of 10℃ / min, a pyrolysis temperature of 400℃, and a pyrolysis time of 2.5h to obtain a honeycomb oxygen storage conditioner.

[0050] The specific surface area of ​​the honeycomb oxygen storage conditioner prepared in this embodiment was determined to be 60.32 m² using a specific surface area and pore size analyzer and a fully automated chemisorption analyzer, respectively. 2 / g, oxygen storage capacity is 79μmol O2 / g. The oxygen storage capacity is reduced in the conditioner without added cerium-zirconium solid solution. The measured oxygen storage capacity is the oxygen stored in the pores of biochar, because biochar itself does not have the ability to store and release oxygen.

[0051] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. The application of a honeycomb oxygen storage conditioner in the biological drying of sludge, wherein the preparation method of the honeycomb oxygen storage conditioner includes the following steps: (1) Mix biomass thoroughly with cerium salt and zirconium salt, soak in alkaline solution, add binder, mix evenly, and obtain precursor; (2) The precursor is pressed into shape, dried, and pyrolyzed to obtain a honeycomb oxygen storage conditioner. The binder is at least one of plant starch and coal tar; The pyrolysis is carried out in a nitrogen atmosphere, with a heating rate of 10~30℃ / min, a pyrolysis temperature of 300~700℃, and a pyrolysis time of 2.5~5 h.

2. The application according to claim 1, characterized in that: The preparation method of the precursor is as follows: take biomass, dry it to constant weight, grind it evenly, mix it thoroughly with cerium salt and zirconium salt, soak it in alkaline solution, filter it, and then add a binder and mix it evenly to obtain the precursor.

3. The application according to claim 1, characterized in that: The biomass is selected from at least one of corn cobs, straw, rice husks, and peanut shells.

4. The application according to claim 1, characterized in that: The biomass is dried and ground evenly before use.

5. The application according to claim 1, characterized in that: The cerium salt is at least one of cerium nitrate, cerium sulfate, and cerium chloride; the zirconium salt is at least one of zirconium nitrate, zirconium oxynitrate, zirconium sulfate, and zirconium chloride.

6. The application according to claim 1, characterized in that: The weight ratio of the biomass to cerium salt and zirconium salt is (10~50): (1~5): (1~5).

7. The application according to claim 1, characterized in that: The alkaline solution is at least one of ammonia water, sodium hydroxide solution, sodium carbonate solution, and ammonium carbonate solution.

8. The application according to claim 1, characterized in that: The soaking time in the alkaline solution is 0.5 to 4 hours.

9. The application according to claim 1, characterized in that: The weight ratio of biomass to binder is 20:(1~5).

10. The application according to claim 1, characterized in that: The compression molding process involves placing the precursor in a honeycomb mold of suitable size, extruding it, and then drying it.

11. The application according to claim 1, characterized in that: The pressed shapes are cubes, cuboids, spheres, and cylinders.

12. The application according to claim 10, characterized in that: The pore size of the honeycomb mold is 0.5~5 mm.