Treatment method for sludge used in the production of unburned bricks

Abstract

The present invention belongs to the field of building materials technology and relates to a method for treating sludge used in the production of unfired bricks. Maggots are added to the sludge after preliminary dehydration, and after a period of treatment, a maggot recovery device is added to the surface of the sludge to allow the maggots to crawl into the maggot recovery device, thereby recovering most of the maggots. After removing the maggot recovery device, high-temperature hot air is used to dry the sludge surface and kill the uncollected maggots on the sludge surface and collect them. The sludge in the biological treatment tray is then discharged for further treatment. The present invention uses maggots to treat the sludge, further reducing the organic matter content in the sludge, which is beneficial for reducing the production of harmful substances such as dioxins in the sludge during the high-temperature drying process. It can also reduce the content of carbon particles in the sludge powder after drying, which helps to improve the strength and density of unfired bricks. The collected live maggots and maggot corpses can be used as feed and other purposes, which can generate certain economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a method for treating sludge used in producing unburned bricks. Background Art

[0002] Using sludge as raw material to make unfired bricks can not only turn waste into treasure and produce high-strength unfired bricks, but also completely solve the sludge treatment problem for large sludge producers such as sewage treatment plants. Therefore, sludge brick making is a win-win production method that benefits the country and the people, is environmentally friendly, beneficial to sludge producers, and profitable for brick manufacturers. It is worthy of in-depth research by relevant companies.

[0003] The production method of making sludge bricks requires pre-treatment of the sludge before it is put into use. The sludge from sewage treatment plants contains a large amount of organic matter. If the organic matter is not treated, it will have a great impact on the strength of unfired bricks. Generally, the sludge is treated and dried at a high temperature of about 500°C to remove the organic matter in the sludge, and at the same time it is dried and powdered. The organic matter in the sludge is prone to produce dioxins and other highly toxic gases when dried at high temperature, which affects the environment. The organic matter has a high carbon content, and carbon particles will also be produced during high-temperature treatment. These carbon particles cannot participate in the hydration reaction of the later strengthening brick body, and will increase the porosity of the brick body to a certain extent, and reduce the density and strength of the brick body.

[0004] In view of this, it is necessary to provide a treatment method that can initially reduce the organic matter content in sludge and reduce pollution and carbon particle generation during sludge drying. Summary of the Invention

[0005] The purpose of the present invention is to provide a biological treatment method that can reduce the organic matter content in sludge and produce certain economic benefits.

[0006] In order to solve the above technical problems, the present invention discloses a method for treating sludge used in the production of unburned bricks, comprising the following steps:

[0007] S1. After preliminary dehydration, the sludge has a moisture content of 70±3%;

[0008] S2. Spread the sludge flat on the biological treatment tray and use a scraper to smooth the top surface of the sludge to a thickness of 8-12 cm.

[0009] S3. Release 2nd-3rd instar maggots and incubate at 30-38°C for 1-2 days;

[0010] S4. Place a maggot recovery device on the sludge surface, so that the maggots crawl into the maggot recovery device to recover most of the maggots;

[0011] S5. Remove the maggot recovery device, use high-temperature hot air to dry the sludge surface and kill the maggots that have not been collected on the sludge surface, and use a brush to remove the maggot bodies on the sludge surface and collect them;

[0012] S6. Discharge the sludge in the biological treatment tray and proceed to the next step of treatment.

[0013] Preferably, in S4, the maggot recovery device includes a frame and a plurality of strip-shaped collecting plates arranged in parallel in the frame, the upper end surfaces of the collecting plates are provided with collecting grooves for placing bait along the length direction, and the edges on both sides of the collecting plates are sloped surfaces.

[0014] Preferably, when the maggot recovery device is placed on the sludge surface, the edges on both sides of the collecting plate are in contact with the sludge surface, so that the maggots can crawl into the collecting trough along the slope.

[0015] Preferably, the bait comprises a mixture of one or more of animal carcasses, excrement or kitchen waste.

[0016] Preferably, a water flow channel connected to the frame is provided in the collecting plate. When collecting maggots, the temperature of the collecting plate is controlled by using water at 25-35° C. so that the collecting plate is at a temperature suitable for the maggots.

[0017] Preferably, in S2, the biological treatment tray is rectangular, and includes a bottom plate and baffles arranged around the bottom plate.

[0018] Preferably, a heating cavity is provided in the bottom plate, and a heat medium or an electric heating plate is provided in the heating cavity.

[0019] Preferably, in S4, after the maggot recovery device is placed on the sludge surface, the bottom plate is heated and the temperature is controlled at 45-60°C to force the maggots to move to the sludge surface, so that more maggots can be collected by the maggot recovery device.

[0020] Preferably, when the bottom plate is heated, the bottom plate is struck or intermittently vibrated with a vibrator to assist in driving the maggots to the sludge surface.

[0021] Preferably, in S3, the maggots are not fed within 2-4 hours before the 2nd-3rd instar maggots are released.

[0022] The method for treating sludge used in producing unburned bricks of the present invention has at least the following advantages:

[0023] 1. Treating sludge with maggots can further reduce the content of organic matter in the sludge, which is beneficial to reduce the production of harmful substances such as dioxins during the high-temperature (above 500°C) drying process of the sludge. It can also reduce the content of carbon particles in the sludge powder after drying, which helps to improve the strength and density of unfired bricks.

[0024] 2. After the activity and metabolism of maggots, the sludge is easier to dehydrate in further processing, which helps to reduce the difficulty of dehydration and the cost of drying sludge.

[0025] 3. Compared with earthworms, which can also process sludge, maggots have a faster metabolism and are more active. The same mass of maggots can process a larger amount of sludge. Most of the organic matter in the sludge is fine and dispersed. Maggots like to drill around everywhere, and the treatment of organic matter is more uniform. However, earthworms of the same mass are relatively poor in terms of activity, sludge treatment volume, and sludge treatment uniformity. In addition, a large number of earthworms can only be obtained through breeding, which is costly. During the use and collection of earthworms, death is inevitable, and the collection of earthworms is more troublesome. Relatively speaking, flies reproduce faster, and maggots can pupate in as fast as 5-6 days. A large number of maggots can be obtained through artificial breeding or attracting flies to lay eggs. This is low-cost and has a short growth cycle. The cost increase caused by the large-scale death of maggots can be tolerated.

[0026] 4. The collected live maggots and maggot corpses can be used as feed and other purposes, and can also generate certain economic benefits and social value, which is conducive to reducing pollution and saving energy consumption during drying, and meets the company's requirements for low-carbon environmental protection and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a structural diagram of a biological treatment disk.

[0028] Figure 2 This is a structural schematic diagram of a maggot recovery device.

[0029] Figure 3 This is a schematic diagram of the three-dimensional structure of a section of a collecting plate.

[0030] Figure 4 A schematic diagram of the internal structure of a collecting plate.

[0031] The numbers in the figure are: A-sludge, B-bait, 1-biological treatment disk, 2-maggot recovery device, 3-frame, 4-collection plate, 5-collection trough, 6-slope, 7-groove, 8-water channel, 9-bottom plate, 10-baffle, 11-heating chamber, 12-electric heating plate. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention through specific examples. 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. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0033] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0034] A method for treating sludge used in the production of unburned bricks comprises the following steps:

[0035] Sludge A undergoes initial dehydration, with a moisture content of 70±3%. At this point, the sludge is relatively soft but not fluid, allowing maggots to easily burrow through it without suffering from oxygen deprivation. The sludge in this example is sewage treatment plant sludge, which is high in organic matter. Generally, sewage treatment plant sludge with a moisture content of 70±3% is relatively soft but still maintains a certain degree of support. Technicians can adjust the moisture content based on actual needs. However, sludges with high chemical content or high acidity or alkalinity, such as those from printing and dyeing plants, can cause significant maggot mortality and are therefore not suitable for maggot treatment.

[0036] S2. In a relatively closed negative pressure greenhouse (a negative pressure greenhouse prevents odor leakage and the escape of maggots and flies), spread the sludge evenly on biological treatment tray 1 and use a scraper to smooth the top surface of the sludge to a thickness of 8-12 cm. Sludge that is too deep is prone to oxygen deficiency, which affects maggot activity and makes it more difficult for maggots to crawl out during collection.

[0037] S3. Release 2-3 instar maggots and treat them at 30-38℃ for 1-2 days. Although 1-instar maggots are active, they are small in size, so their range of activity and sludge treatment capacity are relatively weak. They are also more likely to die in relatively poor sludge environments and where food sources are not abundant. It is best to release 2-instar maggots. Although 3-instar maggots are larger in size and have stronger treatment capacity, they need to pupate in the later stages. If they are not handled in time after pupation, it will cause swarms of flies in the greenhouse. If 3-instar maggots are released, it is advisable to use 3-instar maggots that have just molted to prevent them from pupating during the sludge treatment process.

[0038] S4. Place a maggot recovery device 2 on the sludge surface, allowing maggots to crawl into the device and recover the majority of the maggots. The recovered live maggots can be reused based on their overall development. If they are nearing pupation, they can be made into feed, etc. The maggots collected by the maggot recovery device 2 are then reared and, after a short, normal feeding, can be reused in the next batch of sludge. Each generation of maggots can be reused a maximum of twice.

[0039] S5. Remove the maggot recovery device 2, use high-temperature hot air to dry the sludge surface and kill any uncollected maggots on the sludge surface. Use a brush to remove and collect the maggot corpses on the sludge surface. After collection in S4, some maggots will always remain on the sludge surface. At this time, the maggots inside the sludge have basically crawled out. If these maggots are not collected, they may still affect the sludge quality. However, it is time-consuming and laborious to collect them alive. If they are allowed to crawl and escape, they will turn into flies. At this time, use a spray gun to spray flame or high-temperature hot air to quickly kill the maggots remaining on the sludge surface, while drying the sludge surface or forming a hard shell to facilitate cleaning of the maggot corpses on the sludge surface.

[0040] S6. The sludge in the biological treatment tray 1 is discharged for the next step of treatment. Even if there are some maggots remaining in the sludge, they will be processed in the subsequent dehydration, drying, grinding and other processes.

[0041] like Figure 2 As shown in S4, the maggot recovery device 2 includes a rectangular frame 3 and a plurality of strip-shaped collecting plates 4 arranged in parallel in the frame. The upper end surface of the collecting plate is provided with a collecting groove 5 for placing bait B along the length direction, and the edges on both sides of the collecting plate 4 are sloped surfaces 6.

[0042] When the maggot recovery device is placed on the sludge surface, the edges of the collecting plate on both sides are in contact with the sludge surface, so that the maggots can crawl into the collection tank along the slope. The maggot recovery device should be hoisted or mounted on a track to carry the weight of the maggot recovery device. It should not be placed directly on the sludge surface, otherwise it may sink into the sludge. Figure 3 As shown, in this embodiment, the edges on both sides of the collecting plate 4 protrude downward, so that the middle of the bottom surface of the collecting plate is higher than the two sides, so as to prevent the collecting plate 4 from crushing the maggots directly below it; and a plurality of grooves 7 for the passage of maggots are processed at the bottom of the edges on both sides of the collecting plate, so that the maggots directly below the collecting plate can crawl out along the grooves 7, so that the maggots directly below the collecting plate 4 can also be collected.

[0043] The bait B comprises a mixture of one or more of animal carcasses, excrement or kitchen waste, and the bait can attract the maggots that crawl into the collecting trough and prevent them from crawling out.

[0044] like Figure 4 As shown, the collecting plate is provided with a water channel 8 connected to the frame. The frame is welded with steel pipes and connected to the water channel. The frame has an external cooling water source. When collecting maggots, the temperature of the collecting plate 4 is controlled by using 25-35°C water to keep the collecting plate 4 at a temperature suitable for the maggots. By cooling the collecting plate with water, the maggots are more willing to stay in the collecting tank 5, thereby improving the collection efficiency.

[0045] like Figure 1As shown in S2, the biological treatment tray is rectangular and includes a base plate 9 and baffles 10 arranged around it. Baffles 10 block the sludge A. To prevent maggots from climbing out of the biological treatment tray 1, the upper edge of the baffle should be at least 10 cm above the sludge surface, and the inner upper portion of the baffle should be very smooth to prevent maggots from climbing onto it. One of the baffles around the base plate can be configured as a movable plate. When the sludge in the biological treatment tray needs to be discharged, the movable plate can be lowered or pulled out to remove the sludge.

[0046] A heating cavity 11 is provided in the bottom plate, and a heat medium or an electric heating plate 12 is provided in the heating cavity.

[0047] In S4, after the maggot recovery device is placed on the sludge surface, the base plate is heated to a temperature of 45-60°C, forcing the maggots to migrate toward the sludge surface, thereby increasing their collection potential. In this embodiment, the base plate's initial temperature is set at 45°C and then slowly raised to 50-55°C, giving the maggots ample time to burrow out of the sludge. Maggots instinctively avoid harm at temperatures above 40°C and migrate toward the sludge surface. Upon encountering the cooler, drier collection plate, they easily climb onto it and are collected in the collection tank.

[0048] While heating the bottom plate, tap the plate or use a vibrator to intermittently vibrate the plate to help drive the maggots to the sludge surface. Vibration helps stop the maggots from feeding and speeds up their escape, shortening collection time.

[0049] In S3, before releasing 2-3 instar maggots, the maggots are not fed for 2-4 hours. Sludge is not a delicious food for the maggots, so the maggots are kept hungry to a certain extent. Even if the maggots do not like to eat, they will eat anything they want. It should be noted that the time of not feeding the maggots cannot be too long, otherwise a large number of maggots will die.

[0050] It is worth noting that since maggots shed their skin during their growth (the 1st and 2nd instars shed their skin once each), the shed skin of the maggots should be cleaned before adding them to the sludge.

[0051] At this point, those skilled in the art will recognize that, although a number of exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications consistent with the principles of the present invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and deemed to cover all such other variations or modifications.

Claims

1. A method for treating sludge used in the production of unburned bricks, characterized in that: The steps include: S1. After preliminary dehydration, the sludge has a moisture content of 70±3%; S2. Spread the sludge flat on the biological treatment tray and use a scraper to smooth the top surface of the sludge to a thickness of 8-12 cm. The biological treatment tray is rectangular and includes a bottom plate and baffles arranged around the bottom plate; S3. Release 2nd-3rd instar maggots and incubate at 30-38°C for 1-2 days; S4. Place a maggot recovery device on the sludge surface and heat the bottom plate at a temperature of 45-60°C to force the maggots to move toward the sludge surface, thereby allowing more maggots to be collected by the maggot recovery device. S5. Remove the maggot recovery device, use high-temperature hot air to dry the sludge surface and kill the maggots that have not been collected on the sludge surface, and use a brush to remove the maggot bodies on the sludge surface and collect them; S6. The sludge in the biological treatment tray is discharged for the next step of treatment; In S4, the maggot recovery device includes a frame and a plurality of strip-shaped collecting plates arranged in parallel within the frame, wherein the upper end surfaces of the collecting plates are provided with collecting grooves for placing bait along the length direction, and the edges on both sides of the collecting plates are sloped surfaces; When the maggot recovery device is placed on the sludge surface, the edges of the collecting plate on both sides contact the sludge surface, allowing the maggots to crawl along the slope into the collection tank; The collecting plate is provided with a water channel connected to the frame. When collecting maggots, the temperature of the collecting plate is controlled by using 25-35°C water to keep the collecting plate at a temperature suitable for the maggots. The edges of both sides of the collecting plate protrude downwards, so that the middle of the bottom surface of the collecting plate is higher than the two sides, so as to prevent the collecting plate from crushing the maggots directly below it; The bottom of both sides of the collecting plate is processed with a plurality of grooves for the passage of maggots, so that the maggots directly below the collecting plate can crawl out along the grooves, thereby enabling the maggots directly below the collecting plate to also be collected.

2. A method for treating sludge used in the production of unburned bricks according to claim 1, characterized in that: The bait comprises a mixture of one or more of animal carcasses, excrement or kitchen waste.

3. The method for treating sludge used in producing unburned bricks according to claim 1, wherein: A heating cavity is provided in the bottom plate, and a heat medium or an electric heating sheet is provided in the heating cavity.

4. The method for treating sludge used in producing unburned bricks according to claim 1, wherein: When the bottom plate is heated, the maggots are driven to the surface of the sludge by knocking the bottom plate or using a vibrator to vibrate the bottom plate intermittently.

5. The method for treating sludge used in producing unburned bricks according to claim 1, characterized in that: In S3, the maggots were not fed for 2–4 hours before the release of 2–3 instar maggots.

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