Preparation method and application of a solidifiable bacterial carrier bed

Abstract

A preparation method and application of a curable bacterial carrier bed, relating to the technical field of sewage treatment, comprises the following steps: mixing shell powder, kaolin, and a pore-forming agent, adding water to granulate, rolling into spheres, air-drying, and then sintering once to obtain a porous lightweight inner core; uniformly mixing nano-calcium carbonate, silica sol, a binder, and water to form a slurry, spraying the slurry onto the surface of the porous lightweight inner core, imprinting a surface microwell array through a mold, and then performing a secondary sintering to obtain a ceramic-coated inner core; uniformly mixing titanium oxide sol and sodium alginate to obtain a bacterial affinity solution, dip-coating the solution onto the surface of the ceramic-coated inner core, and forming a gel layer through ultraviolet curing; and femtosecond laser etching capillary airways through to the core layer, wherein the capillary airways have a depth of 950-1050 μm and a diameter of 180-220 μm. The innovative combination of a ceramic multi-level structure and an air-touch regeneration mechanism solves the problem of maintaining bacterial activity in fish tank sewage treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a preparation method of a solidifiable bacterial carrier bed and application thereof. Background Art

[0002] In a closed ornamental fish tank system, biological filtration is the degradation of ammonia nitrogen (NH3-N), nitrite (NO2 - ) is a core link in the process. Currently, mainstream technologies use porous solid carriers (such as ceramsite, activated carbon, and sintered glass rings) to load nitrifying bacteria, allowing water to flow over the carrier surface to achieve biological oxidation of pollutants. However, existing carriers have the following inherent drawbacks:

[0003] Decay of biofilm activity: Due to the accumulation of metabolites and nutrient competition, the microbial community on the surface of the carrier usually ages after 6-12 months, causing the ammonia nitrogen removal rate to drop from the initial >90% to 60-70%, forcing frequent replacement of filter media.

[0004] Risk of carrier clogging: Bacterial extracellular polymers (EPS) and inorganic scale continue to deposit, clogging micropores (especially expanded clay with a pore size of less than 50μm), requiring monthly manual cleaning, which is cumbersome and disrupts the balance of the bacterial flora.

[0005] Sensitive to water quality fluctuations: Traditional carriers lack buffering capacity. When feeding or fish metabolism intensifies, pH fluctuations are greater than 0.5 (ideal range 7.0-8.5), and nitrite peak concentrations are ≥0.5 mg / L. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing a solidifiable bacterial carrier bed, which has achieved the purpose of at least partially solving the above-mentioned problems.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for preparing a solidifiable bacterial carrier bed, comprising the following steps:

[0008] S1. Core preparation: Shell powder, kaolin, and a pore-forming agent were mixed and granulated with water, rolled into spheres, air-dried, and sintered once to obtain a porous lightweight core;

[0009] S2. Coating layer coating: Nano-calcium carbonate, silica sol, binder and water are mixed to form a slurry, the slurry is sprayed onto the surface of the porous lightweight core, the surface micro-well array is imprinted by a mold, and then a secondary sintering is performed to obtain a ceramic coated core;

[0010] S3. Bacterial coating: titanium oxide sol and sodium alginate were mixed to obtain a bacterial solution, which was dip-coated on the surface of the core after the ceramic coating, and a gel layer was formed by UV curing;

[0011] S4. Integrated channel: Femtosecond laser etching capillary airways penetrates the core layer, and the capillary airways have a depth of 950-1050 μm and a diameter of 180-220 μm.

[0012] Furthermore, the core comprises the following raw materials in parts by weight:

[0013] 45-55 parts of shell powder, 20-40 parts of kaolin and 15-25 parts of pore-forming agent;

[0014] Wherein, the pore-forming agent is sawdust pore-forming agent.

[0015] Furthermore, the sintering temperature of the primary sintering is 530-580° C., and the sintering time is 50-70 minutes.

[0016] Furthermore, the slurry includes the following raw materials in parts by weight:

[0017] 35-45 parts of nano calcium carbonate, 25-35 parts of silica sol and 7-9 parts of binder;

[0018] Wherein, the adhesive is polyvinyl alcohol adhesive.

[0019] Furthermore, the mass ratio of the nano-calcium carbonate to the silica sol is (1.2-1.5):1.

[0020] Furthermore, the spraying thickness of the slurry is 400-600 μm, the temperature of the secondary sintering is 280-420° C., the sintering time is 30 min, the diameter of the micro-well is 40-60 μm, and the depth is 90-110 μm.

[0021] Furthermore, the mass percentage of titanium oxide in the bacteriostatic solution is 4-6%, and the mass percentage of sodium alginate is 1.5-2.5%.

[0022] In another aspect, a carrier bed for immobilizing bacteria is provided, which is prepared according to the above method.

[0023] On the other hand, the present invention also provides an application of a solidifiable bacterial carrier bed, wherein the solidifiable bacterial carrier bed prepared according to the above method is applied in fish tanks or sewage treatment fields;

[0024] Before use, soak the carrier bed in nitrifying bacteria solution or add bacterial activator;

[0025] Air is injected into the core of the carrier bed through the air pipe and ejected at high speed through the capillary airway to form a low-pressure vortex at the micro-well mouth to peel off the bacterial micelles in the micro-well and diffuse into the water;

[0026] When the trachea stops injecting air into the core of the carrier bed, the microwell structure preferentially captures free bacteria through the topological matching effect.

[0027] Preferably, the blowing flow rate of the air injected into the carrier bed by the air pipe is 0.4-0.6 L / min, the time interval between two adjacent blowings is 1-3 days, the water flow speed in the fish tank is 0.08-0.12 m / s, and the blowing time is 5-8 minutes.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention solves the problem of maintaining bacterial activity in fish tank sewage treatment through an innovative combination of a ceramic multi-level structure and an air-touch regeneration mechanism. Airflow drive enables autonomous bacterial renewal, while calcium carbonate buffering and titanium oxide self-cleaning work together to stabilize water. The low-energy blowing mode is suitable for the environment of ornamental fish. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0031] A method for preparing a solidifiable bacterial carrier bed comprises the following steps:

[0032] S1. Core preparation: Shell powder, kaolin, and a pore-forming agent were mixed and granulated with water, rolled into spheres, air-dried, and sintered once to obtain a porous lightweight core;

[0033] S2. Coating layer coating: Nano-calcium carbonate, silica sol, binder and water are mixed to form a slurry, the slurry is sprayed onto the surface of the porous lightweight core, the surface micro-well array is imprinted by a mold, and then a secondary sintering is performed to obtain a ceramic coated core;

[0034] S3. Bacterial coating: titanium oxide sol and sodium alginate were mixed to obtain a bacterial solution, which was dip-coated on the surface of the core after the ceramic coating, and a gel layer was formed by UV curing;

[0035] S4. Integrated channel: Femtosecond laser etching of capillary airways extends through the core layer. The capillary airways have a depth of 950-1050 μm and a diameter of 180-220 μm. When the airflow velocity is 1.2-1.8 m / s (0.5 L / min), a low-pressure vortex of ΔP≈1.0-1.5 kPa is generated to peel off the bacterial flocs. If the diameter is too large, the shear force will be insufficient, and if it is too small, the airflow noise will be too high.

[0036] It should be noted that the ceramic core obtained by firing kaolin and shell powder is a lightweight ceramic with low density, which can provide a certain buoyancy to reduce the accumulation at the bottom. Shell powder can slowly release calcium ions to maintain the pH value in the fish tank. The coating layer prepared by nano-calcium carbonate and silica sol has 10-20μm micropores for bacterial colonies to inhabit, and the dissolution of calcium carbonate can buffer acidic metabolites. The bacteriophilic coating can effectively increase the efficiency of directional capture of bacteria. Titanium oxide can achieve the purpose of degrading organic matter through photocatalysis. The internal capillary airway network connects the surface microwells. When the air flow passes through, a low-pressure vortex is formed at the wellhead, which actively strips off the aging biofilm. The stripped bacterial flocs rise to the water body with the bubbles, and are transported by the fish tank water pump to re-colonize on the carrier surface, realizing the "stripping-diffusion-reattachment" cycle.

[0037] In a further embodiment of this example, the core comprises the following raw materials in parts by weight:

[0038] 45-55 parts of shell powder, 20-40 parts of kaolin and 15-25 parts of pore-forming agent;

[0039] The pore-forming agent is sawdust; shell powder provides slow release of calcium ions (the slow release of calcium ions is 0.5-1.2 mg / L·h), which can stabilize the pH within 7.5-8.5. However, if its mass ratio is too high, the core will be too hard and fragile, while if it is too low, it will lead to insufficient buffering of the pH in the fish tank. The pore-forming agent can form through holes with a porosity of 40-50% and a density of 0.7-0.9 g / cm 3 If the mass proportion of the pore-forming agent is too high, the mechanical strength will decrease, while if it is too low, the buoyancy will be insufficient.

[0040] In a further implementation of this embodiment, the sintering temperature of the primary sintering is 530-580°C, and the sintering time is 50-70min; 20-30% of the CaCO3 activity in the shell powder is retained to avoid complete decomposition into CaO, ensure that the clay is fully vitrified, and maintain the integrity of the particles. Too high a sintering temperature will cause the calcium carbonate to completely decompose and lose its sustained release ability, while too long a sintering time will lead to excessive shrinkage and deformation, and too short a time will lead to insufficient strength.

[0041] In a further embodiment of this example, the slurry includes the following raw materials in parts by weight:

[0042] 35-45 parts of nano calcium carbonate, 25-35 parts of silica sol and 7-9 parts of binder;

[0043] Wherein, the adhesive is polyvinyl alcohol adhesive.

[0044] In a further embodiment of this example, the mass ratio of the nano-calcium carbonate to the silica sol is (1.2-1.5):1; within this mass ratio range, both alkalinity buffering and mechanical strength are taken into consideration, otherwise it will lead to increased brittleness or excessive dissolution.

[0045] In a further implementation of this embodiment, the spraying thickness of the slurry is 400-600 μm, the temperature of the secondary sintering is 280-420°C, the sintering time is 30 min, the diameter of the microwell is 40-60 μm, and the depth is 90-110 μm; the depth of the microwell provides sufficient living space for the bacterial colony, matches the bacterial size (1-5 μm), and improves the colonization efficiency by 3 times. If the diameter of the microwell is too large, the bacterial colony will escape, and if the depth is too low, colonization will be more difficult.

[0046] In a further embodiment of this example, the mass percentage of titanium oxide in the bacterial affinity liquid is 4-6%, and the mass percentage of sodium alginate is 1.5-2.5%. Within this range, titanium oxide can achieve an organic matter degradation efficiency of >80% under ultraviolet conditions. Too high a mass percentage can lead to brittle cracking of the coating, while too low a mass percentage can lead to insufficient catalysis. Sodium alginate is used to form a flexible gel layer, which can increase the bacterial adsorption rate by 2 times. However, if the content is too high, it may cause clogging of the microwells, and if it is too low, the adhesion ability is weak and the bacterial adsorption rate is reduced.

[0047] On the other hand, an embodiment of the present invention further provides a carrier bed for solidifying bacteria, which is prepared according to the above method.

[0048] A further embodiment of the present invention also provides an application of a solidifiable bacterial carrier bed, wherein the solidifiable bacterial carrier bed prepared according to the above method is applied in fish tanks or sewage treatment fields;

[0049] Before use, soak the carrier bed in nitrifying bacteria solution or add bacterial activator;

[0050] Air is injected into the core of the carrier bed through the air pipe and ejected at high speed through the capillary airway to form a low-pressure vortex at the micro-well mouth to peel off the bacterial micelles in the micro-well and diffuse into the water;

[0051] When the trachea stops injecting air into the core of the carrier bed, the microwell structure preferentially captures free bacteria through the topological matching effect.

[0052] In a further implementation of this embodiment, the blowing flow rate of the air injected into the carrier bed by the air pipe is 0.4-0.6L / min, the time interval between two adjacent blowing is 1-3d, the water flow speed in the fish tank is 0.08-0.12m / s, and the blowing time is 5-8min.

[0053] Example 1

[0054] S1. Core preparation: 45 parts of shell powder, 20 parts of kaolin, and 15 parts of a pore-forming agent were mixed and granulated with 15% water by mass. The spheres were rolled into spheres with a diameter of 5 mm. The spheres were air-dried for 24 hours and then calcined at 550 ° C for 60 minutes to obtain a porous lightweight core.

[0055] S2. Coating: 35 parts of nano-calcium carbonate, 25 parts of silica sol, 7 parts of a binder, and 22 parts of water were mixed to form a slurry. The slurry was sprayed onto the surface of the porous lightweight core to form a thickness of 500 μm. The surface microwell array was imprinted by a mold, and then sintered at 400°C for 30 minutes to obtain a ceramic coated core.

[0056] S3 pro-bacterial coating: The mass percentage of 5% titanium oxide sol and 2% by mass percentage of sodium alginate was uniformly mixed to obtain a pro-bacterial solution, which was dip-coated on the surface of the core after the ceramic coating, and a gel layer was formed by UV curing;

[0057] S4. Integrated channel: Femtosecond laser etching capillary airways penetrates the core layer, and the capillary airways have a depth of 1000 μm and a diameter of 200 μm.

[0058] Example 2

[0059] S1. Core preparation: 50 parts of shell powder, 30 parts of kaolin, and 20 parts of a pore-forming agent were mixed and granulated with 15% water by mass. The spheres were rolled into spheres with a diameter of 5 mm. The spheres were air-dried for 24 hours and then calcined at 550 ° C for 60 minutes to obtain a porous lightweight core.

[0060] S2. Coating: 40 parts of nano-calcium carbonate, 30 parts of silica sol, 8 parts of a binder, and 22 parts of water were mixed to form a slurry. The slurry was sprayed onto the surface of the porous lightweight core to form a thickness of 500 μm. The surface microwell array was imprinted by a mold, and then sintered at 400°C for 30 minutes to obtain a coated ceramic core.

[0061] S3 pro-bacterial coating: The mass percentage of 5% titanium oxide sol and 2% by mass percentage of sodium alginate was uniformly mixed to obtain a pro-bacterial solution, which was dip-coated on the surface of the core after the ceramic coating, and a gel layer was formed by UV curing;

[0062] S4. Integrated channel: Femtosecond laser etching capillary airways penetrates the core layer, and the capillary airways have a depth of 1000 μm and a diameter of 200 μm.

[0063] Example 3

[0064] S1. Core preparation: 55 parts of shell powder, 40 parts of kaolin, and 25 parts of a pore-forming agent were mixed and granulated with 15% water by mass. The spheres were rolled into spheres with a diameter of 5 mm and air-dried for 24 hours. The spheres were calcined at 550 ° C for 60 minutes to obtain a porous lightweight core.

[0065] S2. Coating: 45 parts of nano-calcium carbonate, 35 parts of silica sol, 9 parts of a binder, and 22 parts of water were mixed to form a slurry. The slurry was sprayed onto the surface of the porous lightweight core to form a thickness of 500 μm. The surface microwell array was imprinted by a mold, and then sintered at 400°C for 30 minutes for a second time to obtain a coated ceramic core.

[0066] S3 pro-bacterial coating: The mass percentage of 5% titanium oxide sol and 2% by mass percentage of sodium alginate was uniformly mixed to obtain a pro-bacterial solution, which was dip-coated on the surface of the core after the ceramic coating, and a gel layer was formed by UV curing;

[0067] S4. Integrated channel: Femtosecond laser etching capillary airways penetrates the core layer, and the capillary airways have a depth of 1000 μm and a diameter of 200 μm.

[0068] The solid carriers prepared in Examples 1 to 3 were placed in fish tanks with the same environment, and the air flow rate of the air pipe injected into the carrier bed, the time interval between two adjacent air blows, and the water flow rate in the fish tank were controlled to obtain the following experimental examples.

[0069] Experimental Example 1

[0070] The solid carrier prepared in Example 2 was placed in a fish tank with a carrier filling rate of 1%. The air flow rate of the air pipe injected into the carrier bed was 0.4 L / min, the time interval between two adjacent air blows was 1 day, and the water flow rate in the fish tank was 0.08 m / s.

[0071] Experimental Example 2

[0072] The solid carrier prepared in Example 2 was placed in a fish tank with a filling rate of 1%. The air flow rate of the air pipe injected into the carrier bed was 0.5 L / min, the time interval between two adjacent air blows was 1 day, and the water flow rate in the fish tank was 0.08 m / s.

[0073] Experimental Example 3

[0074] The solid carrier prepared in Example 2 was placed in a fish tank with a carrier filling rate of 1%. The air flow rate of the air pipe injected into the carrier bed was 0.6 L / min, the time interval between two adjacent blows was 1 day, and the water flow rate in the fish tank was 0.08 m / s.

[0075] Experimental Example 4

[0076] The solid carrier prepared in Example 2 was placed in a fish tank with a filling rate of 1%. The air flow rate of the air pipe into the carrier bed was 0.5 L / min, the time interval between two adjacent air blows was 2 days, and the water flow rate in the fish tank was 0.08 m / s.

[0077] Experimental Example 5

[0078] The solid carrier prepared in Example 2 was placed in a fish tank with a filling rate of 1%. The air flow rate of the air pipe into the carrier bed was 0.5 L / min, the time interval between two adjacent air blows was 3 days, and the water flow rate in the fish tank was 0.10 m / s.

[0079] Experimental Example 6

[0080] The solid carrier prepared in Example 2 was placed in a fish tank with a filling rate of 1%. The air flow rate of the air pipe into the carrier bed was 0.5 L / min, the time interval between two adjacent air blows was 2 days, and the water flow rate in the fish tank was 0.10 m / s.

[0081] Experimental Example 7

[0082] The solid carrier prepared in Example 2 was placed in a fish tank with a carrier filling rate of 1%. The air flow rate of the air pipe injected into the carrier bed was 0.5 L / min, the time interval between two adjacent blows was 2 days, and the water flow rate in the fish tank was 0.12 m / s.

[0083] Experimental Example 8

[0084] The solid carrier prepared in Example 1 was placed in a fish tank with a filling rate of 1%. The air flow rate of the air pipe injected into the carrier bed was 0.5 L / min, the time interval between two adjacent air blows was 2 days, and the water flow rate in the fish tank was 0.10 m / s.

[0085] Experimental Example 9

[0086] The solid carrier prepared in Example 3 was placed in a fish tank with a filling rate of 1%. The air flow rate of the air pipe injected into the carrier bed was 0.5 L / min, the time interval between two adjacent air blows was 2 days, and the water flow rate in the fish tank was 0.12 m / s.

[0087] The fish tanks of Experimental Examples 1-9 were monitored continuously for 3 months, and the results are shown in Table 1 below:

[0088] Table 1

[0089]

[0090] As can be seen from the above table, the solid carrier prepared by this method can maintain the activity of the carrier bacterial community in a dynamic circulation manner, and its ammonia nitrogen removal rate is higher than 95%, which basically avoids the risk of carrier clogging. During the 3-month experimental period, there is no need to replace the carrier and the water quality continues to be clarified. The pH fluctuation of the water quality is less than 0.2, which solves the problem of maintaining bacterial community activity in fish tank sewage treatment. The airflow drive realizes the autonomous renewal of the bacterial community, the calcium carbonate buffer and titanium oxide self-cleaning work together to stabilize the water, and the low-energy blowing mode is suitable for the ornamental fish environment.

[0091] By comparing the data of Experimental Examples 1 to 3, it can be seen that the best effect is achieved when the air blowing flow rate is 0.5L / min, and it will not disturb the fish in the fish tank. By comparing the data of Experimental Examples 2, 4 and 5, it can be seen that the best effect is achieved when the time interval between two adjacent air blows, that is, the frequency of air blows is once every 2 days. It should be noted that the time for each air blow is 5 minutes. By comparing the results of Experimental Examples 4, 6 and 7, it can be seen that the best flow rate of water in the fish tank is 0.10m / s. By comparing the results of Experimental Examples 6, 8 and 9, it can be seen that Example 2 has the best effect.

[0092] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing a solidifiable bacterial carrier bed, characterized in that: The following steps are involved: S1. Core preparation: Shell powder, kaolin, and a pore-forming agent were mixed and granulated with water, rolled into spheres, air-dried, and sintered once to obtain a porous lightweight core; S2. Coating layer coating: Nano-calcium carbonate, silica sol, binder and water are mixed to form a slurry, the slurry is sprayed onto the surface of the porous lightweight core, the surface micro-well array is imprinted by a mold, and then a secondary sintering is performed to obtain a ceramic coated core; S3. Bacterial coating: titanium oxide sol and sodium alginate were mixed to obtain a bacterial solution, which was dip-coated on the surface of the core after the ceramic coating, and a gel layer was formed by UV curing; S4. Integrated channel: Femtosecond laser etching capillary airways penetrates the core layer, and the capillary airways have a depth of 950-1050 μm and a diameter of 180-220 μm.

2. The method for preparing a curable bacterial carrier bed according to claim 1, characterized in that: The core comprises the following raw materials in parts by mass: 45-55 parts of shell powder, 20-40 parts of kaolin and 15-25 parts of pore-forming agent; Wherein, the pore-forming agent is sawdust pore-forming agent.

3. The method for preparing a curable bacterial carrier bed according to claim 1, characterized in that: The sintering temperature of the primary sintering is 530-580° C., and the sintering time is 50-70 minutes.

4. The method for preparing a curable bacterial carrier bed according to claim 1, characterized in that: The slurry includes the following raw materials in parts by mass: 35-45 parts of nano calcium carbonate, 25-35 parts of silica sol and 7-9 parts of binder; Wherein, the adhesive is polyvinyl alcohol adhesive.

5. The method for preparing a curable bacterial carrier bed according to claim 4, characterized in that: The mass ratio of the nano calcium carbonate to the silica sol is (1.2-1.5):

1.

6. The method for preparing a curable bacterial carrier bed according to claim 1, characterized in that: The spraying thickness of the slurry is 400-600 μm, the temperature of the secondary sintering is 280-420° C., the sintering time is 30 minutes, the diameter of the micro-well is 40-60 μm, and the depth is 90-110 μm.

7. The method for preparing a curable bacterial carrier bed according to claim 1, characterized in that: The mass percentage of titanium oxide in the probiotic solution is 4-6%, and the mass percentage of sodium alginate is 1.5-2.5%.

8. A carrier bed capable of curing bacteria, characterized in that: A carrier bed of solidified bacteria prepared according to the preparation method according to any one of claims 1 to 7.

9. An application of a curable bacterial carrier bed, characterized in that: Applying the carrier bed of solidified bacteria prepared by the preparation method according to any one of claims 1 to 7 in the field of fish tanks or sewage treatment; Before use, soak the carrier bed in nitrifying bacteria solution or add bacterial activator; Air is injected into the core of the carrier bed through the air pipe and ejected at high speed through the capillary airway to form a low-pressure vortex at the micro-well mouth to peel off the bacterial micelles in the micro-well and diffuse into the water; When the trachea stops injecting air into the core of the carrier bed, the microwell structure preferentially captures free bacteria through the topological matching effect.

10. The use of the curable bacterial carrier bed according to claim 9, characterized in that: The air flow rate of the air pipe injected into the carrier bed is 0.4-0.6 L / min, the time interval between two adjacent air blows is 1-3 days, the water flow speed in the fish tank is 0.08-0.12 m / s, and the air blow time is 5-8 minutes.

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