Auxiliary material for treating sludge, preparation method, regeneration method and application

Abstract

The present invention belongs to the technical field of solar sludge drying, and specifically relates to an auxiliary material, preparation method, regeneration method and application for treating sludge. The method comprises: (1) punching wood chips to obtain porous wood chips; wherein the diameter of the wood chips is 2-3 cm, and the pores in the porous wood chips have an aperture of 2-4 mm; (2) step-drying the porous wood chips; wherein the step-drying at least comprises a first soaking and a first drying of the porous wood chips, a second soaking and a second drying, and then a third soaking and a third drying. The wood chips prepared by the method have good plasticity and toughness as auxiliary materials for sludge drying, and will not crack or break during drying. The addition of the auxiliary material can quickly absorb free water in the sludge, rapidly reduce the water content of the sewage, increase the porosity of the sludge, promote the loss of water inside the sludge, improve the air permeability and the sludge drying efficiency, and shorten the drying cycle.

Description

Technical Field

[0001] The invention belongs to the technical field of solar sludge drying, and in particular relates to an auxiliary material for treating sludge, a preparation method, a regeneration method and an application thereof. Background Art

[0002] Solar sludge drying is an important method of sludge drying treatment. It uses solar radiation energy and the unsaturated degree of air to evaporate the water in the sludge. Conventional solar drying consumes less energy than other sludge thermochemical drying treatments.

[0003] Solar sludge drying processes include greenhouse drying processes, greenhouse drying processes with auxiliary heating devices, solar thermal drying processes, and a combination of multiple processes. The greenhouse drying process involves spreading the sludge in a light-transmitting solar greenhouse, using the sun's heat to disperse the water in the sludge, using turning equipment to stir the sludge to accelerate the loss of water, and adjusting the airflow in the greenhouse to expel water vapor, thereby achieving the purpose of drying the sludge. Its operation is relatively simple. The greenhouse drying process with auxiliary heating devices generally involves laying a heat-collecting floor heating system on the ground using hot water as the heat transfer medium. The use of external energy, combined with solar energy, can make the sludge drying system more stable. The solar thermal drying process converts solar energy into electrical energy or thermal energy, and uses the converted electrical energy or thermal energy to dry the sludge. Its conversion efficiency is limited by the solar energy resources and the efficiency of the device system.

[0004] Sludge has high moisture content, is viscous, and has a very low porosity. Under natural conditions, it is in an anaerobic environment, making it extremely difficult for internal moisture to dissipate. Solar sludge drying is significantly affected by the weather, especially in winter and the rainy season, when temperatures are low and sunlight is scarce. This can lead to poor sludge drying results, longer drying cycles, and lower drying efficiency, which seriously impacts the stable operation of sludge solar drying projects. Installing heat pump floor heating on the ground of a solar shed can increase the drying rate by providing an external heat source. However, the external heat source used in floor heating increases energy consumption and significantly increases the cost of drying. The application scenarios of solar thermal drying processes are limited, and there are few examples of large-scale utilization. Improving sludge drying efficiency and shortening drying cycles without increasing energy consumption are hot topics in this field. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the existing solar drying technology such as long sludge drying cycle, low efficiency and high energy consumption, thereby providing an auxiliary material, preparation method, regeneration method and application for treating sludge.

[0006] To this end, the present invention provides the following technical solutions.

[0007] A first aspect of the present invention provides a method for preparing an auxiliary material for treating sludge, comprising the following steps:

[0008] (1) punching wood chips to obtain porous wood chips; wherein the diameter of the wood chips is 2-3 cm, and the diameter of the holes in the porous wood chips is 2-4 mm;

[0009] (2) performing step-drying on the porous wood chips; wherein the step-drying at least includes performing a first soaking and a first drying on the porous wood chips, a second soaking and a second drying, and then a third soaking and a third drying.

[0010] Preferably, fresh tree branches and trunks with a diameter greater than 3 cm after pruning for landscaping are used, and the leaves and twigs with a diameter less than 2 cm are removed, and then crushed by a slicer crusher, and screened by a two-stage roller screen to screen out the flake-shaped wood chips as raw materials; the thickness of the wood chips is between 3 mm and 1 cm.

[0011] Preferably, if the moisture content of the wood chips is lower than 30%, they need to be soaked to a moisture content of not less than 30%, and then the holes are punched after the water is drained.

[0012] When the diameter of the wood chip is less than 2.5 cm, the porous wood chip is provided with 3-4 holes;

[0013] Preferably, when the diameter of the wood chip is not less than 2.5 cm, the porous wood chip is provided with 4-7 holes.

[0014] The plurality of holes in the porous wood piece are arranged in a polygonal shape;

[0015] Preferably, the holes in the porous wood piece are arranged in a triangle, square, regular pentagon or regular hexagon shape;

[0016] Preferably, the plurality of holes in the porous wood piece are arranged at at least one of the center point and side length of the polygon.

[0017] The holes in the porous wood piece are arranged at equal intervals;

[0018] Preferably, the distance between the centers of two adjacent holes in the porous wood piece is 0.9-1.8 cm.

[0019] Furthermore, the first soaking temperature is room temperature and the time is 8-10 hours;

[0020] Preferably, the second soaking temperature is 40-45°C and the time is 10-12 hours;

[0021] Preferably, the temperature of the third soaking is 50-55° C., and the time is 12-15 hours.

[0022] In the preparation method, the moisture content of the porous wood chips after the first drying is not higher than 50%;

[0023] Preferably, the moisture content of the porous wood chips after the second drying is not higher than 30%;

[0024] Preferably, the moisture content of the porous wood chips after the third drying is not higher than 20%;

[0025] Preferably, the moisture content of the wood chips is not less than 30 wt % before the punching.

[0026] The second aspect of the present invention provides an auxiliary material for treating sludge prepared by the above method.

[0027] A third aspect of the present invention provides a solar sludge drying method comprising the following steps:

[0028] (1) mixing the auxiliary material for treating sludge prepared by the above-mentioned preparation method with sludge to obtain a mixture;

[0029] (2) Spreading the mixed material to obtain paving material, and turning it over.

[0030] The volume proportion of the auxiliary materials in the mixture is 20-60%;

[0031] Preferably, the thickness of the paving material is 20-40 cm;

[0032] Preferably, the tossing is performed 4-6 times a day;

[0033] Preferably, the solar sludge drying method further comprises the step of obtaining sludge-containing wood chips and dried sludge after separation.

[0034] A fourth aspect of the present invention provides a method for regenerating a sludge-containing auxiliary material, which at least includes vibrating and screening the sludge-containing auxiliary material; the sludge-containing auxiliary material comes from the above-mentioned sludge-containing wood chips.

[0035] Furthermore, when the sludge-containing wood chips are regenerated, when the proportion of pores in the wood chips blocked by sludge is less than 10% of the pores in all wood chips, the sludge-containing wood chips are mixed with the sludge and dried for reuse.

[0036] When the proportion of pores in the wood chips clogged by sludge in all wood chips is not less than 10%, the sludge-containing wood chips are vibrated and screened multiple times to separate the sludge clogged in the wood chip pores, reducing the proportion to less than 10%, thereby realizing the recycling and reuse of the wood chips.

[0037] Preferably, the method further comprises the step of soaking the auxiliary material containing sludge in a solvent;

[0038] When the proportion is still higher than 10% after 3-4 vibration screenings, the sludge-containing wood chips are soaked in a solvent.

[0039] Preferably, the solvent is at least one of water and an acid;

[0040] Preferably, the soaking step also includes a stirring step;

[0041] Preferably, the soaking time is 8-10 hours.

[0042] The technical solution of the present invention has the following advantages:

[0043] 1. The present invention provides a method for preparing an auxiliary material for treating sludge, the method comprising: (1) punching wood chips to obtain porous wood chips; wherein the diameter of the wood chips is 2-3 cm, and the pores in the porous wood chips have a diameter of 2-4 mm; (2) step-drying the porous wood chips; wherein the step-drying at least comprises a first soaking and a first drying of the porous wood chips, a second soaking and a second drying, and a third soaking and a third drying. The wood chips prepared by this method have good plasticity and toughness as auxiliary materials for sludge drying. When the wood chips are mixed with sludge for drying, they will not crack or break, and the structure is stable and the recycling rate is high. The addition of the auxiliary material can, on the one hand, quickly absorb the free water in the sludge, rapidly reduce the water content of the sewage, and on the other hand, increase the porosity of the sludge, improve the air permeability, and strengthen the contact with the air, thereby promoting the loss of water in the sludge, improving the sludge drying efficiency, and shortening the drying cycle. This auxiliary material can be used as an effective supplement to improve solar drying efficiency, particularly during winter and rainy seasons, and reduce the processing costs of solar sludge drying. The auxiliary material of the present invention absorbs moisture, increases sludge porosity, and enhances evaporation, overcoming the shortcomings of existing solar sludge drying processes, such as low efficiency, long cycles, and high energy consumption. It also offers the advantage of high recycling rates.

[0044] Furthermore, by controlling the diameter and pore size of the wood chips, this preparation method ensures that the chips have an appropriate pore structure, preventing cracking and breakage during sludge drying, facilitating processes such as turning and screening. Furthermore, the present invention utilizes step-by-step drying to enhance the plasticity and toughness of the wood chips, preventing cracking and other issues, and improving the recycling rate of auxiliary materials.

[0045] 2. The present invention provides a method for preparing an auxiliary material for treating sludge. By controlling the number and spacing of holes on the wood chips, the present invention can avoid the problem of wood chips being reduced in strength and causing breakage, as well as reducing their permeability and the ability to attach microorganisms.

[0046] The present invention controls the soaking temperature, time, and moisture content of wood chips during step drying and gradually increases the soaking temperature to utilize the memory function of wood materials, making them better adaptable to the solar drying environment, further enhancing the mechanical strength (plasticity, toughness, strength, etc.) of the material, improving the cracking problem of wood chips during the drying process, and reducing the problem of subsequent breakage due to mechanical effects such as turning over, thereby increasing the service life and the number of reuses.

[0047] The preparation method can use discarded tree branches generated by garden pruning as raw materials to prepare auxiliary materials. The material selection is green and environmentally friendly, the cost is low, the processing is convenient, and the recycling of garden waste is promoted.

[0048] 3. The solar sludge drying method provided by the present invention can improve the efficiency of solar sludge drying, shorten the cycle, and does not require an additional heat source during drying, thereby reducing energy consumption and costs.

[0049] 4. The present invention provides a method for regenerating auxiliary materials containing sludge, which can enable the auxiliary materials to be reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0051] Figure 1 This is the arrangement method of the holes on the wood chip in Example 1 of the present invention. DETAILED DESCRIPTION

[0052] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0053] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0054] Example 1

[0055] This embodiment provides a method for preparing an auxiliary material for treating sludge, comprising the following steps:

[0056] The solar boron drying area is divided into four functional areas, namely auxiliary material processing area, auxiliary material drying area, material mixing area and material drying area.

[0057] (1) Prepare auxiliary materials for sludge treatment in the auxiliary material processing area. Select fresh tree branches and trunks with a diameter greater than 3 cm after pruning from urban landscaping. Remove the leaves and fine branches with a diameter less than 2 cm and crush them with a slicer. Use a two-stage drum screen to screen out flake-shaped wood chips with a diameter of 2-2.5 cm. The thickness of the wood chips is between 3 mm and 1 cm. Spread the selected wood chips evenly and use a wood punch to punch small circular holes on the wood chips. Punch three holes arranged in a regular triangle on the wood chips. The setting method is shown in Figure 1 The distance between the centers of two adjacent holes is 1 cm, and the diameter of each hole is 3 mm, so as to obtain a porous wood chip.

[0058] (2) Soak the porous wood chips in water at room temperature for 8 hours, then spread them out in the auxiliary material drying area for drying until the moisture content of the wood chips drops to 50%; then soak them in 45°C water for 10 hours, spread them out in the auxiliary material drying area for drying until the moisture content of the wood chips drops to 30%, and finally soak them in 50°C water for 12 hours, then spread them out in the auxiliary material drying area for drying, so that the moisture content of the wood chips drops to 20%, thereby obtaining auxiliary materials.

[0059] This embodiment also provides a solar sludge drying method, comprising the following steps:

[0060] (1) The moisture content of the sludge to be dried is 78-82%;

[0061] In the material mixing area, the auxiliary materials are mixed with the sludge to obtain a mixture; the volume proportion of the auxiliary materials in the mixture is 30%;

[0062] (2) The mixed material was then placed in a material drying area and spread. The mixed material was turned in situ six times daily using a mud turning machine. The thickness of the spread material was 35 cm. The spread material was dried for 14 days. The wood chips were sieved from the sludge using a vibrating screen with a pore size of 1.5 cm. After separation, the wood chips containing sludge and dried sludge were obtained. The moisture content of the dried sludge was measured. In this example, the moisture content of the dried sludge was reduced from 78-82% to 64-66%.

[0063] This embodiment also provides a method for regenerating the above-mentioned wood chips containing sludge, comprising the following steps:

[0064] The sludge-containing wood chips were placed in the auxiliary material drying area for solar drying to reduce the moisture content of the wood chips to less than 20%. After drying, it was found that the pores in the wood chips blocked by sludge accounted for 17% of the pores in all wood chips. After screening with a vibrating screen three times, each time for 5 minutes, the proportion of pores blocked by sludge in all wood chips was reduced to 9%.

[0065] The recycling rate of the wood chips in this embodiment is 95%. The recycling rate is calculated by the following formula:

[0066]

[0067] The step-drying method used in this embodiment to dry the wood chips can also improve the recycling rate of the auxiliary material. When preparing the auxiliary material, if the step-drying method is changed to soaking for 30 hours at room temperature before drying, and then the auxiliary material is used in sludge drying according to the method of this embodiment, the recycling rate of the obtained auxiliary material is 85%. The recycling rate of the auxiliary material obtained by using the ordinary drying method is significantly lower.

[0068] Example 2

[0069] This embodiment provides a method for preparing an auxiliary material for treating sludge, comprising the following steps:

[0070] The solar boron drying area is divided into four functional areas, namely auxiliary material processing area, auxiliary material drying area, material mixing area and material drying area.

[0071] (1) In the auxiliary material processing area, auxiliary materials for treating sludge are prepared. Fresh tree branches and trunks with a diameter greater than 3 cm after pruning from urban landscaping are selected. After removing leaves and fine branches with a diameter less than 2 cm, they are crushed by a slicer and pulverized. They are sieved with a two-stage drum screen to select flake-shaped wood chips with a diameter of 2.6-3.0 cm and a thickness of 3 mm-1 cm. The selected wood chips are evenly spread and small circular holes are punched on the wood chips using a wood punch. Five holes are punched on the wood chips in a regular pentagonal arrangement, with the center distance between two adjacent holes being 1.2 cm and the diameter of each hole being 3 mm, to obtain hole-containing wood chips.

[0072] (2) Soak the porous wood chips in water at room temperature for 10 hours, then spread them out in the auxiliary material drying area for drying until the moisture content of the wood chips is 45%; then soak them in 45°C water for 12 hours, spread them out in the auxiliary material drying area for drying until the moisture content of the wood chips is 25%, and finally soak them in 55°C water for 15 hours, then spread them out in the auxiliary material drying area for drying, reducing the moisture content of the wood chips to 15%, thereby obtaining auxiliary materials.

[0073] This embodiment also provides a solar sludge drying method, comprising the following steps:

[0074] (1) The moisture content of the sludge to be dried is 70-75%;

[0075] In the material mixing area, the auxiliary materials are mixed with the sludge to obtain a mixture; the volume proportion of the auxiliary materials in the mixture is 20%;

[0076] (2) The mixed material was then placed in a material drying area and spread to obtain a paving material. The mixed material was turned in situ four times daily using a mud turning machine; the paving material had a thickness of 35 cm. The paving material was dried for 10 days, and the wood chips were sieved from the sludge using a vibrating screen with an aperture of 1.5 cm. After separation, the wood chips containing the sludge and the dried sludge were obtained. The moisture content of the dried sludge was measured. In this example, the moisture content of the dried sludge was reduced from 70-75% to 60-62%.

[0077] This embodiment also provides a method for regenerating the above-mentioned wood chips containing sludge, comprising the following steps:

[0078] The sludge-containing wood chips were placed in the auxiliary material drying area for solar drying to reduce the moisture content of the wood chips to less than 20%. After drying, the proportion of pores blocked by sludge in the wood chips was 20% of the pores in all wood chips. After screening with a vibrating screen twice, each time for 5 minutes, the proportion of pores blocked by sludge in all wood chips was reduced to 11%.

[0079] The recycling rate of the wood chips in this embodiment is 96%.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing an auxiliary material for treating sludge, comprising the following steps:

[0082] The solar boron drying area is divided into four functional areas, namely auxiliary material processing area, auxiliary material drying area, material mixing area and material drying area.

[0083] (1) Auxiliary materials for sludge treatment are prepared in the auxiliary material processing area. Fresh tree branches and trunks with a diameter greater than 3 cm after pruning from urban landscaping are selected. After removing leaves and fine branches with a diameter less than 2 cm, they are crushed by a chip crusher and sieved with a two-stage drum screen to select flake-shaped wood chips with a diameter of 3-3.5 cm and a thickness of 3 mm to 1 cm. The selected wood chips are evenly spread and small circular holes are punched on the wood chips using a wood punch. Three holes are punched on the wood chips in an equilateral triangle arrangement, with a center-to-center distance of 1 cm between two adjacent holes and a hole diameter of 5 mm. This produces hole-containing wood chips.

[0084] (2) Soak the porous wood chips in water at room temperature for 8 hours, then spread them out in the auxiliary material drying area for drying until the moisture content of the wood chips reaches 50%; then soak them in 45°C water for 10 hours, spread them out in the auxiliary material drying area for drying until the moisture content of the wood chips reaches 30%, and finally soak them in 50°C water for 12 hours, then spread them out in the auxiliary material drying area for drying, so that the moisture content of the wood chips is reduced to 20%, thereby obtaining auxiliary materials.

[0085] This comparative example also provides a solar sludge drying method, which is the same as Example 1. In this comparative example, the moisture content of the sludge after drying is reduced from 78-82% to 66-68%.

[0086] This comparative example also provides a method for regenerating the above-mentioned sludge-containing wood chips, which is the same as that in Example 1.

[0087] The wood chip recovery rate in this comparative example is 80%.

[0088] Compared with Example 1, when the porous wood chips are used for sludge drying, the moisture content of the sludge after drying is relatively higher. When the wood chips are punched, the pore size is too large, which causes them to crack and break easily during the sludge drying process, which is not conducive to drying and the recycling rate is also low.

[0089] Comparative Experiment 1-2

[0090] The sludge without auxiliary materials was used as comparative experiment 1. The drying process was the same as that of Example 1, except that no auxiliary materials were added. After 17 days of drying, the moisture content of the sludge decreased from 78-82% to 71-73%.

[0091] The sludge without auxiliary materials was used as comparative experiment 2. The drying process was the same as that of Example 2, except that no auxiliary materials were added. After 12 days of drying, the moisture content of the sludge decreased from 70-75% to 65-67%.

[0092] The above results indicate that the addition of the auxiliary material prepared in the present invention during the sludge drying process helps to promote the loss of water from the sludge, improves the drying efficiency, and significantly shortens the drying time.

[0093] Furthermore, the present invention helps to improve the recycling rate of auxiliary materials by controlling the step drying.

[0094] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing an auxiliary material for treating sludge, characterized in that: The following steps are involved: (1) punching holes in wood chips to obtain porous wood chips; wherein the diameter of the wood chips is 2-3 cm, and the diameter of the holes in the porous wood chips is 2-4 mm; (2) performing step-drying on the porous wood chips; wherein the step-drying at least includes performing a first soaking and a first drying on the porous wood chips, a second soaking and a second drying, and then a third soaking and a third drying; the first soaking, the second soaking, and the third soaking are all performed in water; The holes in the porous wood piece are arranged at equal intervals; When the diameter of the wood chip is less than 2.5 cm, the porous wood chip is provided with 3-4 holes; when the diameter of the wood chip is not less than 2.5 cm, the porous wood chip is provided with 4-7 holes; The temperature of the first soaking is room temperature, and the time is 8-10 hours; the temperature of the second soaking is 40-45° C., and the time is 10-12 hours; the temperature of the third soaking is 50-55° C., and the time is 12-15 hours.

2. The preparation method according to claim 1, characterized in that The plurality of holes in the porous wood piece are arranged in a polygonal shape.

3. The preparation method according to claim 2, characterized in that The holes in the porous wood slices are arranged in the shape of triangles, squares, regular pentagons and regular hexagons.

4. The preparation method according to claim 2 or 3, characterized in that The plurality of holes in the porous wood piece are arranged at at least one of a center point and a side length of the polygon.

5. The preparation method according to claim 4, characterized in that The distance between the centers of two adjacent holes in the porous wood piece is 0.9-1.8 cm.

6. The preparation method according to claim 5, characterized in that The moisture content of the porous wood chips after the first drying is not higher than 50%.

7. The preparation method according to claim 6, characterized in that The moisture content of the porous wood chips after the second drying is not higher than 30%.

8. The preparation method according to claim 7, characterized in that The moisture content of the porous wood chips after the third drying is not higher than 20%.

9. The preparation method according to claim 8, characterized in that Before punching, the moisture content of the wood chips is not less than 30wt%.

10. An auxiliary material for treating sludge obtained by the preparation method according to any one of claims 1 to 9.

11. A solar sludge drying method, characterized in that: The following steps are involved: (1) The auxiliary material for treating sludge prepared by the preparation method according to any one of claims 1 to 9 is mixed with sludge to obtain a mixture; (2) Spreading the mixture to obtain paving material, and turning it over.

12. The solar sludge drying method according to claim 11, characterized in that: The volume proportion of the auxiliary materials in the mixture is 20-60%.

13. The solar sludge drying method according to claim 12, characterized in that: The thickness of the paving material is 20-40 cm.

14. The solar sludge drying method according to claim 13, characterized in that: The turning and tossing is performed 4-6 times a day.

15. The solar sludge drying method according to claim 14, characterized in that: The solar sludge drying method further comprises the step of obtaining sludge-containing wood chips and dried sludge after separation.

16. A method for regenerating auxiliary materials containing sludge, characterized in that: The method at least comprises vibrating and screening the auxiliary material containing sludge; the auxiliary material containing sludge comes from the sludge-containing wood chips obtained by the solar sludge drying method according to claim 15.

17. The regeneration method according to claim 16, characterized in that: The method also includes the step of soaking the auxiliary material containing sludge in a solvent.

18. The regeneration method according to claim 17, characterized in that: The solvent is at least one of water and acid.

19. The regeneration method according to claim 18, characterized in that: The step of stirring is also included while the soaking is being carried out.

20. The regeneration method according to claim 19, characterized in that: The soaking time is 8-10 hours.

Images