A biodegradable microfiller, its preparation method and applications

Abstract

This invention discloses a biodegradable microfiller, its preparation method, and its uses. The preparation method includes the following steps: 1) Preparation of the core spheres: Rice husk ash, clay, and sewage sludge with a moisture content of 50wt%–65wt% are mixed and reacted at high temperature to obtain core spheres; 2) Fixation of the exfoliation layer: Rice husk ash and alum are mixed to form a first mixture, which is then added to the core spheres and subjected to high-temperature treatment to obtain semi-finished filler spheres; 3) Fixation of the cross-layer: Sludge with a moisture content of less than 30wt% and clay are mixed to form a second mixture. The semi-finished filler spheres are then contacted with the second mixture and subjected to firing treatment to obtain irregular spherical microfillers. This technical solution utilizes waste to treat waste, not only providing a use for sewage sludge but also reducing the amount of suspended filler used in wastewater treatment and the amount of dewatering agents used in subsequent sludge dewatering. It achieves economic and social benefits while solving environmental pollution problems.

Description

Technical Field

[0001] This invention belongs to the field of environmental governance, and in particular relates to a biodegradable microfiller prepared from sewage sludge, its preparation method and uses. Background Technology

[0002] Due to the industry's long-standing emphasis on water treatment while neglecting sludge disposal, sludge treatment has become a major bottleneck restricting the healthy development of wastewater treatment plants.

[0003] Municipal sewage sludge has an extremely high moisture content, reaching 99% or even higher. It also contains heavy metals, organic matter, plant nutrients such as nitrogen and phosphorus, as well as toxic and harmful organic compounds. The sludge flocs are in a gel-like state, easily decomposed and even causing epidemics, posing a significant risk of secondary pollution. Mechanical dewatering is the most common method for sludge dewatering, with common dewatering machines including centrifuges, filter presses, and vacuum filters. This mainly relies on the pressure difference across the filter medium as the driving force to forcibly separate the sludge from the water. However, direct mechanical dewatering cannot effectively reduce the moisture content of the sludge. Even after thickening and mechanical dewatering, the moisture content of sludge from wastewater treatment plants remains as high as about 85%, and the high cost of sludge drying has not been resolved. The state advocates reducing the moisture content of sludge to below 60%. In existing technologies, those skilled in the art typically add large amounts of conditioning agents to further reduce the moisture content of the sludge.

[0004] The conventional water treatment process in urban water supply plants includes coagulation, flocculation, sedimentation, filtration, and disinfection. The coagulation process generates a large amount of sludge, known as water supply sludge. This sludge contains not only a large amount of pollutants from natural water sources, such as suspended solids, colloidal substances, algae, and coloring organic matter, but also a significant amount of wastewater treatment chemicals. Compounds such as CaCO3, SiO2, Fe2O3, and Al2O3 are the main components of water supply sludge. These main components are precisely the same as the main components of the conditioners added during sludge dewatering; therefore, water supply sludge is often commercially available as a sludge dewatering agent.

[0005] How to utilize the existing resource of sewage sludge, how to solve the dewatering problem of municipal sludge, how to reduce the amount of packing material used in sewage treatment, how to reduce the amount of dewatering agents used in municipal sludge dewatering, and how to take a holistic approach to these issues, reduce them simultaneously, and utilize them in a complementary manner are all bottleneck problems that urgently need to be solved and overcome. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a waste-to-waste technical solution: a method for preparing biodegradable microfillers using sewage sludge, and its application. This biodegradable microfiller prepared from sewage sludge can solve the dewatering problem of municipal sludge, effectively reduce the amount of suspended fillers used in municipal wastewater treatment, and the amount of dewatering agents used in subsequent municipal sludge dewatering. To achieve the above and other related objectives, this invention is obtained through the following technical solution.

[0007] The first aspect of this invention provides a method for preparing biodegradable microfillers using sewage sludge, comprising the following steps:

[0008] 1) Preparation of core spheres: Rice husk ash, clay and water supply sludge with a moisture content of 50wt% to 65wt% are mixed and reacted at high temperature to obtain core spheres;

[0009] 2) Fixation of the peeling layer: Rice husk ash and alum are mixed to form a first mixture, which is then brought into contact with the core ball and treated at high temperature to obtain a semi-finished filler ball;

[0010] 3) Fixing of the cross-layer: Water supply sludge with a water content of less than 30 wt% and clay are mixed to form a second mixture. The semi-finished packing balls are brought into contact with the second mixture and then subjected to firing treatment to obtain irregular spherical micro packings.

[0011] Preferably, in step 1), the mass ratio of rice husk ash, clay, and water supply sludge with a moisture content of 50wt% to 65wt% is 1 to (3:1): (6 to 10).

[0012] Preferably, in step 1), the water supply sludge with a moisture content of 50wt% to 65wt% is obtained by air drying after passing through a sludge dewatering machine.

[0013] Preferably, in step 1), the high-temperature reaction is carried out under vacuum conditions.

[0014] Preferably, in step 1), the temperature of the high-temperature reaction is 120-160°C, and the reaction time is 4-6 hours.

[0015] Preferably, in step 1), after the high-temperature reaction is completed, the material is sieved using a 60-80 mesh sieve.

[0016] Preferably, in step 1), cooling is further included after the high-temperature reaction is completed. More preferably, the cooling is vacuum cooling, and the time spent in the vacuum environment is 3 to 7 seconds.

[0017] Preferably, in step 2), the mass ratio of rice husk ash to alum is 2:(1-4).

[0018] Preferably, in step 2), the volume ratio of the first mixture to the core sphere is 1:(4-8).

[0019] Preferably, in step 2), the contact time between the first mixture and the core spheres is 5 to 10 minutes. This is to prevent the spheres from sticking together during addition.

[0020] Preferably, in step 2), the temperature of the high-temperature treatment is 100-120°C.

[0021] Preferably, in step 3), the water supply sludge with a moisture content of less than 30 wt% is obtained by drying or dehydration after passing through a sludge dewatering machine.

[0022] Preferably, in step 3), the mass ratio of the water supply sludge with a moisture content of less than 30 wt% to the clay is (4-7):1.

[0023] Preferably, in step 3), the mass ratio of the semi-finished packing balls to the second mixture is (7-9):1.

[0024] Preferably, in step 3), the firing temperature is 900–1500℃, and the firing time is 0.5–1 hour. During the firing process, substances such as sludge water, rice husk ash, and alum dissolve, promoting the formation of porous, irregular shapes in the micro-filler, which helps to enrich the activated sludge.

[0025] The addition of clay serves as reinforcement and shaping to prevent cracking of the filler during firing. The amount of clay added is relatively small to ensure the filler's stable formation within a short period, ideally 20-30 days.

[0026] A second aspect of the present invention provides a biodegradable microfiller prepared using the preparation method described above.

[0027] Preferably, the biodegradable microfiller is an irregular sphere with a diameter of 3 to 5 cm.

[0028] A third aspect of the present invention provides an application of the biodegradable microfiller as described above in the treatment of wastewater in the activated sludge process and its derived aerobic processes.

[0029] Preferably, in the activated sludge process for wastewater treatment, the biodegradable microfiller is used as a growth carrier for activated sludge to purify wastewater and is equivalent to chemical agents to promote sludge dewatering.

[0030] Preferably, the aerobic tank suitable for the biodegradable microfiller includes one or more of the A2 / O or A / O system aerobic tank.

[0031] Preferably, the hydraulic retention time (HRT) of the aerobic tank is 4 to 6 hours, and the oxygenation efficiency (EP) is 6 to 8 kg O2 / (kW·h).

[0032] The fourth aspect of the present invention provides a wastewater treatment method using biodegradable microfillers as described above. When using the activated sludge process to treat wastewater, when the effective volume of the aerobic tank is 100%, the amount of activated sludge added is 40% to 55% of the effective volume, and the amount of biodegradable microfillers added is 10% to 20% of the effective volume.

[0033] Preferably, when using the activated sludge process to treat wastewater, when the effective volume of the aerobic tank is 100%, the amount of activated sludge added is 20% to 40% of the effective volume, the amount of biodegradable micro-filler added is 20% to 30% of the effective volume, and the amount of suspended filler added is 15% to 40% of the effective volume.

[0034] In this invention, the addition of clay is to prevent the filler from cracking during the firing process, which would cause the microfiller to break prematurely during application, thereby affecting the adsorption effect of the microfiller on activated sludge. At the same time, it avoids the phenomenon of microfiller accumulation in the aerobic tank and excessively high activated sludge concentration caused by premature breakage of the microfiller.

[0035] In this invention, rice husk ash can be used as a coagulant aid during wastewater treatment before the micro-filler is crushed, thereby helping the micro-filler to stabilize. Furthermore, because rice husk ash can generate sodium silicate solids under appropriate reaction conditions, and sodium silicate solids are unstable over a long period, this promotes the degradation of the micro-filler. As described above, this invention provides a method for preparing biodegradable micro-fillers using water supply sludge, along with its application. This biodegradable micro-filler, prepared from water supply sludge, solves the problem of municipal sludge dewatering while effectively reducing the amount of suspended filler used in wastewater treatment and the amount of dewatering agents used in subsequent municipal sludge dewatering, thus turning waste into treasure and treating waste with waste. It achieves good economic and social benefits while solving environmental pollution problems. Attached Figure Description

[0036] Figure 1 The diagram shown is a structural schematic of the biodegradable microfiller of the present invention.

[0037] The annotations in the attached figures are explained as follows:

[0038] 100 overlapping layers

[0039] 200 peel layer

[0040] 300 Core Spheres Detailed Implementation

[0041] The following specific examples illustrate the implementation of the present invention to verify its practical feasibility. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0042] It should be noted that the process equipment or apparatus not specifically specified in the following embodiments are all conventional equipment or apparatus in the art. Furthermore, it should be understood that the scope of protection of this invention is not limited to the specific embodiments described below. One or more method steps mentioned in this invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the terminology used in the embodiments of this invention is for describing specific embodiments and not for limiting the scope of protection of this invention. Test methods not specifying specific conditions in the following embodiments are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0043] The following embodiments employ a specific method for preparing biodegradable microfillers using sewage sludge, comprising the following steps:

[0044] 1) Preparation of the core sphere:

[0045] 1-1) After squeezing the water supply sludge with a sludge dewatering machine, air dry it to a moisture content of 50wt% to 65wt% to obtain water supply sludge with a moisture content of 50wt% to 65wt%.

[0046] 1-2) Mix rice husk ash, clay and water supply sludge with a moisture content of 50wt% to 65wt% thoroughly, wherein the mass ratio of rice husk ash, clay and water supply sludge with a moisture content of 50wt% to 65wt% is (1 to 3): 1: (6 to 10);

[0047] 1-3) Under vacuum conditions, a high-temperature reaction is carried out at a temperature of 120–160°C for a time of 4–6 hours;

[0048] 1-4) After the high-temperature reaction, the sample passes through a 60-80 mesh sieve and falls into a vacuum cylinder. The falling time is 3-7 seconds. Finally, it falls into the ice water in the vacuum cylinder and cools rapidly to form the core sphere.

[0049] 2) Fixation of the peeling layer:

[0050] 2-1) Mix rice husk ash and alum to form a first mixture, wherein the mass ratio of rice husk ash to alum is 2:(1-4);

[0051] 2-2) The first mixture obtained in 2-1) is brought into contact with the core sphere, the volume ratio of the first mixture to the core sphere is 1:(4-8), and the contact time between the first mixture and the core sphere is 5-10 min;

[0052] 2-3) Perform high-temperature treatment, the temperature of which is 100-120℃, to obtain semi-finished packing balls.

[0053] 3) Fixing the overlapping layer:

[0054] 3-1) After the water supply sludge is squeezed by a sludge dewatering machine, it is dried or dried until the moisture content is below 30 wt% to obtain water supply sludge with a moisture content of below 30 wt%;

[0055] 3-2) A second mixture is formed by mixing water supply sludge with a moisture content of less than 30 wt% and clay, wherein the mass ratio of the water supply sludge with a moisture content of less than 30 wt% to the clay is (4-7):1;

[0056] 3-3) The semi-finished packing balls are brought into contact with the second mixture in 3-2), the mass ratio of the semi-finished packing balls to the second mixture is (7-9):1, and then a firing treatment is performed. The firing temperature is 900-1500℃ and the firing time is 0.5-1h to obtain irregular spherical micro-packings.

[0057] Example 1

[0058] This embodiment provides a method for preparing biodegradable microfillers using sewage sludge, comprising the following steps:

[0059] 1) Preparation of the core sphere:

[0060] 1-1) After squeezing the water supply sludge with a sludge dewatering machine, air-dry it to a moisture content of 50 wt% to obtain water supply sludge with a moisture content of 50 wt%.

[0061] 1-2) Mix rice husk ash, clay and water supply sludge with a moisture content of 50 wt% thoroughly. The mass ratio of rice husk ash, clay and water supply sludge with a moisture content of 50 wt% is 2:1:7. The masses of rice husk ash, clay and water supply sludge with a moisture content of 50 wt% are 60 g, 30 g and 210 g, respectively.

[0062] 1-3) Under vacuum conditions, a high-temperature reaction is carried out at a temperature of 140℃ for a reaction time of 4 hours;

[0063] 1-4) After the high-temperature reaction, the sample passes through a 60-mesh sieve and falls into a vacuum cylinder. The falling time is 5 seconds. Finally, the sample falls into the ice water in the vacuum cylinder and cools rapidly to form a core sphere.

[0064] 2) Fixation of the peeling layer:

[0065] 2-1) Mix rice husk ash and alum to form a first mixture, wherein the mass ratio of rice husk ash to alum is 1:1;

[0066] 2-2) The first mixture obtained in 2-1) is brought into contact with the core sphere, wherein the volume ratio of the first mixture to the core sphere is 1:5, and the contact time is 5 min;

[0067] 2-3) Perform high-temperature treatment at 100°C to obtain semi-finished packing balls.

[0068] 3) Fixing the overlapping layer:

[0069] 3-1) After the water supply sludge is squeezed by a sludge dewatering machine, it is dried or dried to a moisture content of 30 wt% to obtain water supply sludge with a moisture content of 30%.

[0070] 3-2) A second mixture is formed by mixing water supply sludge with a moisture content of 30 wt% and clay, wherein the mass ratio of water supply sludge with a moisture content of 30 wt% to clay is 5:1;

[0071] 3-3) The semi-finished packing balls are brought into contact with the second mixture in 3-2), the mass ratio of the semi-finished packing balls to the second mixture is 7:1, and then a firing treatment is performed. The firing temperature is 1200℃ and the firing time is 0.5h to obtain irregular spherical micro-packing. The average diameter of the spheres obtained at this time is 5cm and the total weight of the spheres is about 150g.

[0072] Example 2

[0073] This embodiment provides a method for preparing biodegradable microfillers using sewage sludge, comprising the following steps:

[0074] 1) Preparation of the core sphere:

[0075] 1-1) After squeezing the water supply sludge with a sludge dewatering machine, air-dry it to a moisture content of 65 wt% to obtain water supply sludge with a moisture content of 65 wt%.

[0076] 1-2) Mix rice husk ash, clay and water supply sludge with a moisture content of 65 wt% thoroughly. The mass ratio of rice husk ash, clay and water supply sludge with a moisture content of 65 wt% is 2:1:8. The masses of rice husk ash, clay and water supply sludge with a moisture content of 65 wt% are 68 g, 34 g and 272 g, respectively.

[0077] 1-3) Under vacuum conditions, a high-temperature reaction is carried out at a temperature of 130°C for 5 hours.

[0078] 1-4) After the high-temperature reaction, the sample passes through a 60-mesh sieve and falls into a vacuum cylinder. The falling time is 5 seconds. Finally, the sample falls into the ice water in the vacuum cylinder and cools rapidly to form a core sphere.

[0079] 2) Fixation of the peeling layer:

[0080] 2-1) Mix rice husk ash and alum to form a first mixture, wherein the mass ratio of rice husk ash to alum is 1:1;

[0081] 2-2) The first mixture obtained in 2-1) is brought into contact with the core sphere, wherein the volume ratio of the first mixture to the core sphere is 1:5, and the contact time is 5 min;

[0082] 2-3) Perform high-temperature treatment at 100°C to obtain semi-finished packing balls.

[0083] 3) Fixing the overlapping layer:

[0084] 3-1) After the water supply sludge is squeezed by a sludge dewatering machine, it is dried or dried to a moisture content of 30wt% to obtain water supply sludge with a moisture content of 30wt%.

[0085] 3-2) A second mixture is formed by mixing water supply sludge with a moisture content of 30 wt% and clay, wherein the mass ratio of water supply sludge with a moisture content of 30 wt% to clay is 5:1;

[0086] 3-3) The semi-finished packing balls are brought into contact with the second mixture in 3-2), the mass ratio of the semi-finished packing balls to the second mixture is 7:1, and then a firing treatment is performed. The firing temperature is 1200℃ and the firing time is 0.5h to obtain irregular spherical micro-packing. The average diameter of the spheres obtained at this time is 5cm and the total weight of the spheres is about 150g.

[0087] Example 3

[0088] This embodiment provides a method for preparing biodegradable microfillers using sewage sludge, comprising the following steps:

[0089] This embodiment provides a method for preparing biodegradable microfillers using sewage sludge, comprising the following steps:

[0090] 1) Preparation of the core sphere:

[0091] 1-1) After squeezing the water supply sludge with a sludge dewatering machine, air-dry it to a moisture content of 50 wt% to obtain water supply sludge with a moisture content of 50 wt%.

[0092] 1-2) Mix rice husk ash, clay and water supply sludge with a moisture content of 50 wt% thoroughly. The mass ratio of rice husk ash, clay and water supply sludge with a moisture content of 50 wt% is 2:1:7. The masses of rice husk ash, clay and water supply sludge with a moisture content of 50 wt% are 50 g, 25 g and 175 g, respectively.

[0093] 1-3) Under vacuum conditions, a high-temperature reaction is carried out at a temperature of 130°C for 5 hours.

[0094] 1-4) After the high-temperature reaction, the sample passes through a 60-mesh sieve and falls into a vacuum cylinder. The falling time is 5 seconds. Finally, the sample falls into the ice water in the vacuum cylinder and cools rapidly to form a core sphere.

[0095] 2) Fixation of the peeling layer:

[0096] 2-1) Mix rice husk ash and alum to form a first mixture, wherein the mass ratio of rice husk ash to alum is 1:1;

[0097] 2-2) The first mixture obtained in 2-1) is brought into contact with the core sphere, wherein the volume ratio of the first mixture to the core sphere is 1:5, and the contact time is 5 min;

[0098] 2-3) Perform high-temperature treatment at 100°C to obtain semi-finished packing balls.

[0099] 3) Fixing the overlapping layer:

[0100] 3-1) After the water supply sludge is squeezed by a sludge dewatering machine, it is dried or dried to a moisture content of 25wt% to obtain water supply sludge with a moisture content of 25wt%.

[0101] 3-2) A second mixture is formed by mixing water supply sludge with a moisture content of 25 wt% and clay, wherein the mass ratio of water supply sludge with a moisture content of 25% to clay is 6:1;

[0102] 3-3) The semi-finished packing balls are brought into contact with the second mixture in 3-2), the mass ratio of the semi-finished packing balls to the second mixture is 8:1, and then a firing process is carried out. The firing temperature is 1200℃ and the firing time is 0.5h to obtain irregular spherical micro-packing. The average diameter of the spheres obtained at this time is 4cm and the total weight of the spheres is about 130g.

[0103] Comparative Example 1

[0104] The difference between this comparative example and Example 1 is that, except for step 1), rice husk ash is not added, the rest is exactly the same as in Example 1.

[0105] Comparative Example 2

[0106] The difference between this comparative example and Example 1 is that, except for step 1), no clay is added, the rest is exactly the same as in Example 1.

[0107] Comparative Example 3

[0108] The difference between this comparative example and Example 1 is that, except for step 1), the masses of rice husk ash, clay and water supply sludge with a water content of 50wt% are 20g, 10g and 80g respectively; in step 3), the average diameter of the obtained spheres is 2cm and the total weight of the spheres is about 60g, and the rest is exactly the same as in Example 1.

[0109] Comparative Example 4

[0110] The difference between this comparative example and Example 1 is that, except for step 1), the masses of the rice husk ash, clay, and water supply sludge with a water content of 50wt% are 75g, 37.5g, and 262.5g, respectively; and in step 3), the average diameter of the obtained spheres is 6cm, and the total weight is about 200g. The rest of the parts are exactly the same as in Example 1.

[0111] Comparative Example 5

[0112] The difference between this comparative example and Example 1 is that, except for step 1), the masses of rice husk ash, clay and water supply sludge with a water content of 50wt% are 87.6g, 43.8g and 306.6g, respectively; in step 3), the average diameter of the obtained spheres is 7cm and the total weight is about 225g, and the rest is exactly the same as in Example 1.

[0113] Comparative Example 6

[0114] The difference between this comparative example and Example 1 is that, except for step 1), the masses of rice husk ash, clay and water supply sludge with a water content of 50wt% are 100g, 50g and 350g respectively; in step 3), the average diameter of the obtained spheres is 8cm and the total weight is about 260g, and the rest is exactly the same as in Example 1.

[0115] Comparative Example 7

[0116] The difference between this comparative example and Example 1 is that, except for step 1), the masses of rice husk ash, clay and water supply sludge with a water content of 50wt% are 112.6g, 56.3g and 394.1g respectively; in step 3), the average diameter of the obtained spheres is 9cm and the total weight is about 290g, and the rest is exactly the same as in Example 1.

[0117] Comparative Example 8

[0118] The difference between this comparative example and Example 1 is that, except for step 1), the masses of rice husk ash, clay and water supply sludge with a water content of 50wt% are 125g, 62.5g and 437.5g respectively; in step 3), the average diameter of the obtained spheres is 10cm and the total weight is about 345g, and the rest is exactly the same as in Example 1.

[0119] Application Example 1

[0120] The biodegradable microfiller prepared in Example 1 was applied to the aerobic tank of the A / O system. The HRT of the aerobic tank was 4 hours, and the oxygenation power efficiency (EP) was 6 kg O2 / (kW·h).

[0121] When the effective volume of the aerobic tank is 100%, the dosage of activated sludge is 20% of the effective volume, the dosage of biodegradable micro-filler is 20% of the effective volume, and the dosage of suspended filler is 15% of the effective volume.

[0122] In wastewater treatment, biodegradable micro-fillers function similarly to suspended fillers, providing attachment and growth sites for microorganisms in activated sludge to purify wastewater. During continuous aeration and sludge discharge, the biodegradable micro-fillers gradually disperse and break down, exposing their core spheres. Due to the strong phosphorus adsorption capacity of the sludge, they can remove a large amount of phosphorus from the wastewater during sludge discharge, achieving a phosphorus removal rate of up to 94%. After the biodegradable micro-fillers break down, they are mixed with the sludge.

[0123] After sludge discharge, the sludge dewatering process continues:

[0124] First, the sludge is concentrated: the sludge is initially dewatered using a sludge dewatering machine, and the water in the sludge is concentrated and discharged.

[0125] Further filtration: The concentrated sludge is directly fed into a filter press to further remove water from the sludge;

[0126] Re-drying: The filtered sludge is dried using a dryer.

[0127] Experiments show that when using the biodegradable filler provided by this invention, the amount of suspended filler added is only 15% of the effective volume, greatly reducing the use of suspended filler in existing technologies. Furthermore, no chemical agents, including flocculants and coagulants, need to be added during sludge dewatering, reducing the amount of dewatering agents used. Moisture content testing of the dewatered sludge shows that the sludge moisture content decreased from approximately 99% to 55%, and the sludge volume was reduced to one-third of its original size.

[0128] The packing materials prepared in Example 1 and Comparative Examples 1-8 were respectively placed in the aerobic tank of the A / O system for application testing. The test results are shown in Table 1.

[0129] Table 1

[0130]

[0131]

[0132] As shown in Table 1, the biodegradable microfiller obtained using the method of this application (the microfiller prepared in Example 1) has good porosity. This is because substances such as water from the sludge, rice husk ash, and alum in the microfiller dissolve during the firing process, promoting the formation of a porous, irregular shape, which helps to enrich the activated sludge. After being placed in the aerobic tank, it has good floating performance and strong adhesion of activated sludge. During continuous aeration and sludge discharge, the filler breaks down and degrades within 20-30 days, and can be used as a chemical agent to help with subsequent sludge dewatering. Compared with Example 1, the microfiller provided in Comparative Example 1 remains intact for a long time after being placed in the aerobic tank, showing incomplete breakage and incomplete degradation, and therefore cannot be used as a chemical agent for subsequent sludge dewatering. Compared with Example 1, the microfiller provided in Comparative Example 2 has poorer formation and breaks down during the firing process. Compared to Example 1, the micro-filler provided in Comparative Example 3 remained intact for a long time after being placed in the aerobic tank, and was not easily broken or degraded. Therefore, it could not be used as a chemical agent for subsequent sludge dewatering. Compared to Example 1, the micro-fillers provided in Comparative Examples 4-8 had larger volumes, and after being placed in the aerobic tank, they broke up earlier, had poor floating performance, poor adhesion to activated sludge, and poor wastewater purification capacity.

[0133] In summary, the biodegradable microfiller prepared by the technical solution provided by this invention can act as a suspended filler in the sewage treatment process before crushing, effectively reducing the large amount of phosphorus in the sewage and reducing the amount of suspended filler required. After crushing, it can also act as a chemical agent in the sludge dewatering process, which is beneficial to sludge dewatering and reduces the amount of chemical agents used in the sludge dewatering process. At the same time, it also provides a suitable outlet for the use of water supply sludge, which has the effect of turning waste into treasure and treating waste with waste. It can solve environmental pollution problems while achieving good economic and social benefits.

[0134] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing biodegradable microfillers using sewage sludge, characterized in that, The preparation method includes the following steps: 1) Preparation of core spheres: Rice husk ash, clay and water supply sludge with a moisture content of 50wt% to 65wt% are mixed and reacted at high temperature to obtain core spheres; 2) Fixation of the peeling layer: Rice husk ash and alum are mixed to form a first mixture, which is then brought into contact with the core ball and treated at high temperature to obtain a semi-finished filler ball; 3) Fixing of the cross-layer: Water supply sludge with a water content of less than 30 wt% and clay are mixed to form a second mixture. The semi-finished packing balls are brought into contact with the second mixture and then subjected to firing treatment to obtain irregular spherical micro packings.

2. The preparation method according to claim 1, characterized in that, In step 1), the mass ratio of rice husk ash, clay, and water supply sludge with a moisture content of 50wt% to 65wt% is (1 to 3): 1: (6 to 10). And / or, in step 1), the water supply sludge with a moisture content of 50wt% to 65wt% is obtained by air drying after passing through a sludge dewatering machine; And / or, in step 1), the high-temperature reaction is carried out under vacuum conditions; And / or, the temperature of the high-temperature reaction is 120-160°C, and the reaction time is 4-6 hours; And / or, in step 1), after the high-temperature reaction is completed, the sample is sieved using a 60-80 mesh screen; And / or, in step 1), cooling is also included after the high-temperature reaction is completed.

3. The preparation method according to claim 2, characterized in that, The cooling is performed using vacuum cooling.

4. The preparation method according to claim 1, characterized in that, In step 2), the mass ratio of rice husk ash to alum is 2:(1-4); And / or, in step 2), the volume ratio of the first mixture to the core spheres is 1:(4-8); And / or, in step 2), the contact time between the first mixture and the core ball is 5 to 10 minutes; And / or, in step 2), the temperature of the high-temperature treatment is 100-120°C.

5. The preparation method according to claim 1, characterized in that, In step 3), the water supply sludge with a moisture content of less than 30 wt% is obtained by drying or dehydration after passing through a sludge dewatering machine. And / or, in step 3), the mass ratio of the water supply sludge with a moisture content of less than 30 wt% to clay is (4-7):1; And / or, in step 3), the mass ratio of the semi-finished packing balls to the second mixture in the semi-finished packing balls is (7-9):1; And / or, in step 3), the firing temperature is 900-1500℃ and the firing time is 0.5-1h.

6. A biodegradable microfiller prepared by the preparation method according to any one of claims 1 to 5.

7. The biodegradable microfiller according to claim 6, characterized in that, The biodegradable microfiller is an irregular sphere with an average diameter of 3 to 5 cm.

8. The application of the biodegradable microfiller as described in any one of claims 6 to 7 in the treatment of wastewater in the activated sludge process and its derived aerobic processes.

9. The application according to claim 8, characterized in that, In the activated sludge process for wastewater treatment, the biodegradable microfiller serves as a growth carrier for activated sludge to purify wastewater and is equivalent to chemical agents in promoting sludge dewatering.

10. A wastewater treatment method using the biodegradable micro-filler according to any one of claims 6 to 7, characterized in that, When using the activated sludge process to treat wastewater, if the effective volume of the aerobic tank is 100%, the amount of activated sludge added is 40% to 55% of the effective volume, and the amount of the biodegradable micro-filler added is 10% to 20% of the effective volume.

11. The processing method according to claim 10, characterized in that, When using the activated sludge process to treat wastewater, when the effective volume of the aerobic tank is 100%, the amount of activated sludge added is 20% to 40% of the effective volume, the amount of biodegradable micro-filler added is 20% to 30% of the effective volume, and the amount of suspended filler added is 15% to 40% of the effective volume.

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