A method for producing fish protein fertilizer from sludge produced in surimi processing

Abstract

This invention provides a method for producing fish protein fertilizer from sludge generated during surimi processing, belonging to the field of surimi sludge reuse technology. The method includes the following steps: 1) Preliminary filtration of sludge generated during surimi processing through a mechanical screen to collect the sludge; 2) Adding a flocculant to the sludge and adjusting the pH to the isoelectric point to cause protein and other suspended solids to flocculate and precipitate; 3) Placing the collected precipitate in a collection tank for preliminary dehydration and homogenization; 4) Placing the dehydrated and homogenized precipitate in a high-temperature hydrolysis tank for hydrolysis at 180°C to 200°C and under corresponding high pressure to break down the organic matter structure in the sludge; 5) Transferring the hydrolyzed product to a high-temperature fermentation tank for fermentation under aerobic conditions. By using this method, an efficient and environmentally friendly sludge treatment method is provided, converting sludge generated during surimi processing into high-value-added fish protein fertilizer.

Description

Technical Field

[0001] This invention belongs to the field of fish surimi sludge reuse technology, specifically relating to a method for producing fish protein fertilizer from sludge generated during fish surimi processing. Background Technology

[0002] Sludge is a byproduct of seafood processing and wastewater treatment, containing large amounts of organic matter and nutrients. Traditional treatment methods result in environmental pollution and resource waste.

[0003] Currently, higher efficiency is becoming the development direction for sludge treatment and disposal technologies. my country's sludge treatment and disposal technologies are relatively backward, with low treatment efficiency. In the future, with continuous technological advancements and equipment upgrades, sludge treatment and disposal technologies will develop towards greater efficiency and intelligence to improve treatment efficiency and reduce treatment costs.

[0004] Currently, the main methods for sludge treatment and disposal in my country include landfill, incineration, and land application. Landfill is widely used due to its simplicity and low cost, but it consumes a large amount of land resources and poses environmental problems such as leachate pollution of groundwater. Incineration can reduce sludge volume and kill pathogens, but it can produce secondary pollution, such as toxic substances like dioxins. Land application allows for the resource utilization of sludge, but the content of heavy metals and toxic substances in the sludge needs to be considered.

[0005] Furthermore, sustainability and resource utilization will become important directions for sludge treatment and disposal. Sludge, as an organic waste, has certain resource value. In the future, sludge treatment and disposal technologies will place greater emphasis on the resource utilization of sludge, such as converting it into bio-fertilizer and bio-energy through anaerobic digestion and aerobic fermentation, thereby achieving sludge reduction, resource recovery, and harmlessness. Summary of the Invention

[0006] The purpose of this invention is to provide a method for producing fish protein fertilizer using sludge generated from fish paste processing, aiming to solve the problems of relatively backward sludge treatment and disposal technology, low treatment efficiency, and secondary pollution caused by existing technologies.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for producing fish protein fertilizer using sludge from fish paste processing includes the following steps:

[0009] S1. The sludge generated during the surimi processing is initially filtered through a mechanical screen to collect the sludge. Then, flocculant is added to the sludge to adjust the pH value to the isoelectric point, so that the protein and other suspended matter flocculate and precipitate.

[0010] S2. Solid-liquid separation is achieved through methods such as precipitation, filtration, or centrifugation, and the precipitate is collected;

[0011] S3. Place the collected sediment into a collection tank for preliminary dehydration and homogenization.

[0012] S4. Place the dehydrated and homogenized precipitate in a high-temperature hydrolysis tank and hydrolyze it at a temperature of 180°C to 200°C and under corresponding high pressure to destroy the organic structure in the sludge.

[0013] S5. The hydrolyzed products are transferred to a high-temperature fermentation tank for fermentation under aerobic conditions. The fermented sludge is then transported from the fermentation tank to a filter press for filtration.

[0014] S6. Transfer the sludge after filter pressing from the filter press to the drying equipment for drying, and then use the crushing equipment to crush the dried sludge.

[0015] S7. The crushed material is sieved to remove particles larger than 200 mesh. The sieved material is then sealed and packaged to form the final fish protein fertilizer product.

[0016] As a preferred embodiment of the present invention, in step S4, the temperature of the high-temperature hydrolysis tank is between 180°C and 200°C, and the pressure is between 4 and 6 MPa.

[0017] In a preferred embodiment of the present invention, in step S5, the sludge is evenly distributed onto the filter cloth of the filter press, and the water in the sludge is squeezed out by the mechanical pressure of the filter press.

[0018] As a preferred embodiment of the present invention, in step S6, the sludge is preheated before entering the drying stage and dried at a low temperature of less than 100°C.

[0019] As a preferred embodiment of the present invention, in step S3, a simple dehydration device is used to preliminarily dehydrate the precipitate, and at the same time, a stirrer or mixing device is used to stir the precipitate.

[0020] As a preferred embodiment of the present invention, in step S7, particles larger than 200 mesh retained on the screen are collected and returned to the crusher for further crushing. Then, the particle size and uniformity of the sieved material are checked.

[0021] As a preferred embodiment of the present invention, in step S1, the flocculant is one or more of the following: cationic polyacrylamide, polyferric sulfate, polyferric silicate, sodium alginate, chitosan, ferric ammonium sulfate, aluminum sulfate, ferric sulfate, aluminum chloride, ferric chloride, and alum.

[0022] As a preferred embodiment of the present invention, in step S2, the solid-liquid separation is carried out using a vertical flow sedimentation tank, in which fish protein precipitates.

[0023] As a preferred embodiment of the present invention, in step S5, the hydrolyzed product is mixed with microbial inoculant in a high-temperature fermenter for fermentation treatment.

[0024] In a preferred embodiment of the present invention, all the biogas produced by the high-temperature fermentation is collected by a biogas storage tank, which provides energy for the high-temperature hydrolysis tank, the fermentation tank, and the low-temperature drying process.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. In this scheme, a high-temperature reaction tank is used to sterilize the sludge; a high-temperature fermentation tank is used to shorten the sludge fermentation time; biogas generated by the fermentation tank is used to provide the energy required for the high-temperature hydrolysis tank, fermentation tank, and low-temperature drying process; and a biological deodorizer is added to the fermentation tank to remove the odor generated during the fermentation process.

[0027] 2. In this scheme, sludge is effectively converted into high-value-added fish protein fertilizer, reducing environmental pollution. The high-temperature hydrolysis and fermentation process improves the biological stability of sludge and the fertilizer efficiency. The low-temperature drying and pulverization process retains the nutrients in the sludge and improves the quality of the fertilizer. Attached Figure Description

[0028] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0029] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] Please see Figure 1 The present invention provides the following technical solutions:

[0033] A method for producing fish protein fertilizer using sludge from fish paste processing includes the following steps:

[0034] S1. The sludge generated during the surimi processing is initially filtered through a mechanical screen to remove larger solid impurities. The filtered sludge is then transported to a sedimentation tank. Depending on the properties of the sludge, a suitable flocculant (such as polyaluminum chloride, polyacrylamide, etc.) is added to the sludge, and the pH value is adjusted to the isoelectric point to cause proteins and other suspended solids to flocculate and precipitate.

[0035] S2. The flocculant and sludge are thoroughly mixed by the mixing equipment to ensure the flocculation reaction. Under the action of the flocculant and pH adjustment, the suspended solids and proteins in the sludge begin to flocculate to form larger flocs, which gradually settle to the bottom of the tank. The supernatant after sedimentation can be discharged through the overflow or discharge system, while the settled flocs are collected by the sludge scraper or sludge suction equipment.

[0036] S3. Use sludge pumps, scrapers or other conveying equipment to transfer the collected sediment to the collection tank. Use sludge dewatering screens or simple dewatering equipment, such as belt filter presses, to perform preliminary dewatering of the sediment. At the same time, use agitators or mixing equipment to stir the sediment to ensure its uniform composition. During this process, monitor the sediment concentration in the collection tank regularly. When the sludge in the collection tank reaches a certain amount or dewatering degree, transfer it to the next treatment stage.

[0037] S4. The dehydrated and homogenized precipitate is placed in a high-temperature hydrolysis tank for high-temperature hydrolysis. The temperature of the high-temperature hydrolysis tank is controlled between 180°C and 200°C, and the pressure is between 4 and 6 MPa. Under these conditions, the cell walls and organic structures in the precipitate are destroyed, releasing soluble organic matter. The precipitate after the reaction needs to be cooled rapidly to prevent secondary polymerization during subsequent biodegradation. The energy for high-temperature hydrolysis is provided by biogas produced by the high-temperature fermentation tank.

[0038] S5. The hydrolyzed products are transferred to a high-temperature fermentation tank for fermentation under aerobic conditions to further decompose organic matter and improve the biological stability of the sludge. A biological deodorizer is added during fermentation to prevent odor generation. The fermented sludge is then transported from the fermentation tank to a filter press, where it is evenly distributed onto the filter cloth. The mechanical pressure of the filter press squeezes out the water from the sludge, and the squeezed liquid is collected through the filter cloth and the filter press's drainage system. Solid particles form a filter cake on the filter cloth. The filter cake after filtration has good dewatering performance and calorific value, facilitating subsequent drying and energy utilization. After filtration, the filter cake is removed from the filter press and prepared for the next drying process. The collected filtrate needs further treatment to meet emission standards or for recycling. After the filtration operation is completed, the filter press is cleaned to remove residual sludge and ensure the normal operation of the equipment.

[0039] S6. Transfer the sludge after filter pressing from the filter press to the drying equipment for drying. The drying equipment should be a low-temperature drying device, such as a belt dryer, fluidized bed dryer, or rotary drum dryer, and the drying should be carried out at a low temperature below 100°C to reduce the loss of organic matter and nutrients in the sludge. Before entering the drying stage, the sludge may need to be preheated to improve drying efficiency. The heat source should be biogas produced during high-temperature fermentation to reduce energy consumption. Monitor the temperature, humidity, and sludge flowability during the drying process to ensure uniform drying. Control the final moisture content of the sludge by adjusting the drying time and hot air flow. The exhaust gas generated during the drying process needs to be treated by dust removal and purification equipment to meet emission standards. The dried sludge is then crushed using a crushing device.

[0040] S7. Prepare the crushed material for sieving. Select the appropriate screen size and type according to the required final particle size and uniformity requirements. Put the material into a sieving device such as a vibrating screen, drum screen, or rotary screen. Turn on the sieving device to make the material vibrate or roll on the screen. Collect the fine material that passes through the screen. This material has reached the required particle size and can be directly used for packaging or further mixing. Particles larger than 200 mesh are intercepted by the screen and returned to the crusher for further crushing, while smaller particles fall through the screen holes. If finer particle size classification is required, it can be achieved through multi-stage sieving, with each stage using a screen with a different aperture. Then, seal and package the sieved material separately to form the final fish protein fertilizer product.

[0041] Example 2

[0042] A method for producing fish protein fertilizer using sludge from fish paste processing includes the following steps:

[0043] S1. The sludge generated during the surimi processing is initially filtered through a mechanical screen to remove larger solid impurities. The filtered sludge is then transported to a sedimentation tank. Depending on the properties of the sludge, a suitable flocculant (such as polyaluminum chloride, polyacrylamide, etc.) is added to the sludge to adjust the pH value to the isoelectric point. The metering pump is automatically dosing the chemicals using a batch control method. By setting the pH meter parameters, the pH of the wastewater is controlled between 4.50 and 5.00. Simultaneously, adding an appropriate amount of CaCl2 utilizes the binding of Ca2+ with troponin in fish meat, causing it to lose water and harden, accelerating its settling. This also removes some phosphates from the sludge wastewater. Since protein is an amphoteric electrolyte, the amount of charge on its charged groups varies depending on the uniformity of the solution. When protein is at its isoelectric point, the protein molecules exist as zwitterions, with a net molecular charge of zero (i.e., equal positive and negative charges). At this point, the protein molecules in the solution lack mutual repulsion due to the absence of like charges, weakening the intermolecular forces. The particles easily collide and aggregate, forming precipitation. Therefore, proteins at their isoelectric point have the lowest solubility and are most prone to forming precipitates. Flocculants such as cationic polyacrylamide, polyferric sulfate, polyferric silicate, sodium alginate, chitosan, ferric ammonium sulfate, aluminum sulfate, ferric sulfate, aluminum chloride, ferric chloride, and alum were selected and used in a flocculant formulation to recover protein from sludge generated during fish paste processing.

[0044] S2. The flocculant and sludge are thoroughly mixed by the mixing equipment to ensure the flocculation reaction. Under the action of the flocculant and pH adjustment, the suspended solids and proteins in the sludge begin to flocculate to form larger flocs, which gradually settle to the bottom of the tank. The supernatant after sedimentation can be discharged through the overflow or discharge system, while the settled flocs are collected by the sludge scraper or sludge suction equipment.

[0045] S3. Use sludge pumps, scrapers or other conveying equipment to transfer the collected sediment to the collection tank. Use sludge dewatering screens or simple dewatering equipment, such as belt filter presses, to perform preliminary dewatering of the sediment. At the same time, use agitators or mixing equipment to stir the sediment to ensure its uniform composition. During this process, monitor the sediment concentration in the collection tank regularly. When the sludge in the collection tank reaches a certain amount or dewatering degree, transfer it to the next treatment stage.

[0046] S4. The dehydrated and homogenized precipitate is placed in a high-temperature hydrolysis tank and subjected to high-temperature hydrolysis using AS.1398 protease. The temperature of the high-temperature hydrolysis tank is controlled between 180°C and 200°C, and the pressure is between 4 and 6 MPa. Under these conditions, the cell walls and organic structures in the precipitate are destroyed, releasing soluble organic matter. The precipitate after the reaction needs to be rapidly cooled to prevent secondary polymerization during subsequent biodegradation. The energy for high-temperature hydrolysis is provided by biogas produced by the high-temperature fermenter.

[0047] S5. The hydrolyzed products are transferred to a high-temperature fermentation tank for fermentation under aerobic conditions to further decompose organic matter and improve the biological stability of the sludge. A biological deodorizer is added during fermentation to prevent odor generation. The fermented sludge is then transported from the fermentation tank to a filter press, where it is evenly distributed onto the filter cloth. The mechanical pressure of the filter press squeezes out the water from the sludge, and the squeezed liquid is collected through the filter cloth and the filter press's drainage system. Solid particles form a filter cake on the filter cloth. The filter cake after filtration has good dewatering performance and calorific value, facilitating subsequent drying and energy utilization. After filtration, the filter cake is removed from the filter press and prepared for the next drying process. The collected filtrate needs further treatment to meet emission standards or for recycling. After the filtration operation is completed, the filter press is cleaned to remove residual sludge and ensure the normal operation of the equipment.

[0048] S6. Transfer the sludge after filter pressing from the filter press to the drying equipment for drying. The drying equipment should be a low-temperature drying device, such as a belt dryer, fluidized bed dryer, or rotary drum dryer, and the drying should be carried out at a low temperature below 100°C to reduce the loss of organic matter and nutrients in the sludge. Before entering the drying stage, the sludge may need to be preheated to improve drying efficiency. The heat source should be biogas produced during high-temperature fermentation to reduce energy consumption. Monitor the temperature, humidity, and sludge flowability during the drying process to ensure uniform drying. Control the final moisture content of the sludge by adjusting the drying time and hot air flow. The exhaust gas generated during the drying process needs to be treated by dust removal and purification equipment to meet emission standards. The dried sludge is then crushed using a crushing device.

[0049] S7. Prepare the crushed material for sieving. Select the appropriate screen size and type based on the required final particle size and uniformity. Place the material into a vibrating screen, drum screen, or rotary screen. Turn on the sieving equipment to allow the material to vibrate or roll on the screen. Collect the fine material that passes through the screen; this material has reached the required particle size and can be directly used for packaging or further mixing. Particles larger than 200 mesh are retained by the screen and returned to the crusher for further crushing. Smaller particles fall through the screen openings. For finer particle size classification, multi-stage sieving can be used, with each stage using a screen with a different aperture. Then, seal and package the sieved material separately to form the final fish protein fertilizer product.

[0050] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing fish protein fertilizer from sludge generated in processing of surimi, characterized by, Includes the following steps: S1. The sludge generated during the surimi processing is initially filtered through a mechanical screen to collect the sludge. Then, flocculant is added to the sludge to adjust the pH value to the isoelectric point, so that the protein and other suspended matter flocculate and precipitate. S2. Solid-liquid separation is achieved by at least one of precipitation, filtration or centrifugation, and the precipitate is collected; S3. Place the collected sediment into a collection tank for preliminary dehydration and homogenization. S4. The precipitate after dehydration and homogenization is placed in a high-temperature hydrolysis tank for high-temperature hydrolysis reaction. The temperature of the high-temperature hydrolysis tank is between 180°C and 200°C, and the pressure is between 4 and 6 MPa. S5. The hydrolyzed products are transferred to a high-temperature fermentation tank for fermentation under aerobic conditions. The fermented sludge is then transported from the fermentation tank to a filter press for filtration. In the high-temperature fermentation tank, the hydrolyzed products are mixed with microbial agents for fermentation. All the biogas produced by the high-temperature fermentation is collected by a biogas storage tank, which provides energy for the high-temperature hydrolysis tank, fermentation tank, and low-temperature drying process. S6. Before entering the drying stage, the sludge is preheated and dried at a low temperature of less than 100°C. The sludge after filter pressing is transferred from the filter press to the drying equipment for drying. The dried sludge is then crushed using a crushing equipment. S7. The crushed material is sieved to remove particles larger than 200 mesh. The sieved material is then sealed and packaged to form the final fish protein fertilizer product. The particles larger than 200 mesh retained on the screen are collected and returned to the crusher for further crushing. The particle size and uniformity of the sieved material are then checked.

2. The method according to claim 1, wherein the fish protein fertilizer is produced from the sludge generated in the processing of surimi. In step S5, the sludge is evenly distributed onto the filter cloth of the filter press, and the water in the sludge is squeezed out by the mechanical pressure of the filter press.

3. The method according to claim 2, wherein the fish protein fertilizer is produced from the sludge generated in the processing of surimi. In step S3, a simple dehydration device is used to initially dehydrate the precipitate, and at the same time, a stirrer or mixing device is used to stir the precipitate.

4. The method for producing fish protein fertilizer from sludge generated during fish paste processing according to claim 3, characterized in that, In step S1, the flocculant is one or more of the following: cationic polyacrylamide, polyferric sulfate, polyferric silicate, sodium alginate, chitosan, ferric ammonium sulfate, aluminum sulfate, ferric sulfate, aluminum chloride, ferric chloride, and alum.

5. A method for producing fish protein fertilizer from sludge generated during fish paste processing according to claim 4, characterized in that, In step S2, the solid-liquid separation is carried out using a vertical flow sedimentation tank, where fish protein precipitates.

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