Method for preparing fish protein fertilizer from sludge generated by surimi processing

Abstract

The invention provides a method for preparing a fish protein fertilizer from sludge generated by surimi processing, and belongs to the technical field of surimi sludge reutilization, the method for preparing the fish protein fertilizer from the sludge generated by surimi processing comprises the following steps: preliminarily filtering the sludge generated in the surimi processing process through a mechanical grid, collecting the sludge, and drying the sludge to obtain the fish protein fertilizer. Adding a flocculating agent into the sludge, and adjusting the pH value to an isoelectric point to flocculate and precipitate protein and other suspended matters; putting the collected precipitate into a collecting tank, and carrying out preliminary dehydration and homogenization treatment on the precipitate; placing the dehydrated and homogenized precipitate in a high-temperature hydrolysis tank, and hydrolyzing at the temperature of 180-200 DEG C and under the corresponding high-pressure condition to destroy the organic matter structure in the sludge; transferring a hydrolyzed product to a high-temperature fermentation tank, and fermenting under an aerobic condition; by using the scheme, an efficient and environment-friendly sludge treatment method is provided, and the sludge generated by surimi processing is converted into the fish protein fertilizer with high additional value.

Description

Technical Field

[0001] The invention belongs to the technical field of fish paste sludge recycling, and in particular relates to a method for making fish protein fertilizer by utilizing sludge generated by fish paste processing. Background Art

[0002] Sludge is a byproduct of aquatic product processing and sewage treatment, containing a large amount of organic matter and nutrients. Traditional treatment methods have problems of environmental pollution and resource waste.

[0003] At present, high efficiency will become the development direction of sludge treatment and disposal technology. my country's sludge treatment and disposal technology is relatively backward and the treatment efficiency is low. In the future, with the continuous advancement of technology and the upgrading of equipment, sludge treatment and disposal technology will develop in a more efficient and intelligent direction to improve treatment efficiency and reduce treatment costs.

[0004] At present, the main methods of sludge treatment and disposal in my country include landfill, incineration, land utilization, etc. Among them, landfill is widely used because of its simplicity and low cost, but landfill will occupy a lot of land resources and there are environmental problems such as leachate contaminating groundwater. Incineration can reduce the volume of sludge and kill pathogens, but it will produce secondary pollution, such as dioxins and other toxic substances. Land utilization can realize the resource utilization of sludge, but it is necessary to consider the content of heavy metals and toxic and harmful substances in the sludge.

[0005] Thirdly, sustainability and resource utilization will become important directions for sludge treatment and disposal. As an organic waste, sludge has certain resource value. In the future, sludge treatment and disposal technology will pay more attention to the resource utilization of sludge, such as converting sludge into biofertilizer, bioenergy, etc. through anaerobic digestion, aerobic fermentation and other technologies, so as to achieve sludge reduction, resource utilization and harmlessness. Summary of the invention

[0006] The purpose of the present invention is to provide a method for making fish protein fertilizer using sludge produced by fish paste processing, aiming to solve the problem that sludge treatment and disposal technology in the prior art is relatively backward, the treatment efficiency is low and secondary pollution will be generated.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing fish protein fertilizer using sludge produced by fish paste processing comprises the following steps:

[0009] S1. Preliminarily filtering the sludge generated during the surimi processing through a mechanical grid, collecting the sludge, adding a flocculant to the sludge, adjusting the pH value to the isoelectric point, and causing protein and other suspended matter to flocculate and precipitate;

[0010] S2. Separate the solid from the liquid by sedimentation, filtration or centrifugation, and collect the precipitate;

[0011] S3, placing the collected sediment into a collection tank, and performing preliminary dehydration and homogenization treatment on the sediment;

[0012] S4, placing the dehydrated and homogenized precipitate in a high temperature hydrolysis tank, and hydrolyzing it at a temperature of 180°C to 200°C and under corresponding high pressure conditions to destroy the structure of organic matter in the sludge;

[0013] S5. The hydrolyzed product is transferred to a high-temperature fermentation tank for fermentation under aerobic conditions, and the fermented sludge is transported from the fermentation tank to a filter press for filtration treatment;

[0014] S6, transferring the sludge after filtration from the filter press to a drying device for drying, and then crushing the dried sludge using a crushing device;

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

[0016] As a preferred solution 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] As a preferred solution of the present invention, in step S5, the sludge is evenly distributed on the filter cloth of the filter press, and the moisture in the sludge is squeezed out by the mechanical pressure of the filter press.

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

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

[0020] As a preferred solution of the present invention, in step S7, the particles larger than 200 mesh retained on the screen are collected and returned to the pulverizer for re-pulverization, and then the particle size and uniformity of the sieved material are quality checked.

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

[0022] As a preferred solution of the present invention, in step S2, the solid-liquid separation is performed using a vertical flow sedimentation tank, and the fish protein is precipitated in the sedimentation tank.

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

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

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[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 fermentation time of the sludge; the 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 deodorant is added to the fermentation tank to remove the odor generated during the fermentation process.

[0027] 2. In this scheme, the 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 the sludge and the fertilizer efficiency of the fertilizer. The low-temperature drying and crushing process retains the nutrients in the sludge and improves the quality of the fertilizer. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 It is a flowchart of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] See also Figure 1 , the present invention provides the following technical solutions:

[0033] A method for preparing fish protein fertilizer using sludge produced by fish paste processing comprises the following steps:

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

[0035] S2. The flocculant and sludge are fully mixed by the stirring equipment to ensure the flocculation reaction. Under the action of the flocculant and pH adjustment, the suspended matter and protein in the sludge begin to flocculate to form larger flocs, and gradually settle to the bottom of the pool. The supernatant after precipitation can be discharged through the overflow or discharge system, and the precipitated flocs are collected by the scraper or sludge suction equipment;

[0036] S3. Use a sludge pump, scraper or other conveying equipment to transfer the collected sediment to a collection tank, use a sludge dewatering screen or simple dewatering equipment, such as a belt filter press, to perform preliminary dewatering on the sediment, and use an agitator or mixing equipment to stir the sediment at the same time to ensure that its composition is uniform. During this process, the sediment concentration in the collection tank is regularly monitored. When the sludge in the collection tank reaches a certain amount or dehydration degree, it is transferred to the next treatment stage;

[0037] S4. Place the dehydrated and homogenized precipitate in a high-temperature hydrolysis tank for high-temperature hydrolysis reaction. 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 this condition, the cell wall and organic structure in the precipitate are destroyed, releasing soluble organic matter. The precipitate after the reaction needs to be cooled quickly to prevent secondary polymerization in the subsequent biodegradation process. The energy for high-temperature hydrolysis is provided by the biogas generated by the high-temperature fermentation tank;

[0038] S5. The hydrolyzed product is transferred to a high-temperature fermentation tank and fermented under aerobic conditions to further decompose organic matter and improve the biological stability of the sludge. A biological deodorant is added during the fermentation process to avoid the generation of odor. The fermented sludge is transported from the fermentation tank to a filter press, and then the sludge is evenly distributed on the filter cloth of the filter press. The water in the sludge is squeezed out by the mechanical pressure of the filter press. The squeezed liquid is collected through the filter cloth and the drainage system of the filter press. The solid particles form a filter cake on the filter cloth. The filter cake after filtration has good dehydration performance and calorific value, which is convenient for subsequent drying and energy utilization. After the filtration is completed, the filter cake is unloaded from the filter press and prepared for the next step of drying. The collected filtrate needs to be further processed to meet the emission standards or recycled. After the filtration operation is completed, the filter press is cleaned to remove the residual sludge to ensure the normal operation of the equipment;

[0039] S6. Transfer the sludge after filtration from the filter press to the drying equipment for drying. The drying equipment uses low-temperature drying equipment, such as a belt dryer, a fluidized bed dryer or a rotary drum dryer. The drying is 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 the drying efficiency. The heat source is the biogas generated during high-temperature fermentation to reduce energy consumption. The temperature, humidity and fluidity of the sludge during the drying process are monitored to ensure uniform drying. The final moisture content of the sludge is controlled 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 the emission standards. The dried sludge is then crushed by crushing equipment;

[0040] S7. Prepare the crushed material for screening. According to the required final particle size and uniformity requirements, select the appropriate screen size and type. Put the material into screening equipment such as vibrating screen, drum screen or rotary screen. Turn on the screening equipment to make the material vibrate or roll on the screen. Collect the fine material passing through the screen. These materials have 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 grinder for re-crushing, while smaller particles fall through the holes in the screen. If more detailed particle size classification is required, it can be achieved through multi-stage screening. Screens with different apertures are used at each stage. Then the screened materials are sealed and packaged separately to form the final fish protein fertilizer product.

[0041] Example 2

[0042] A method for preparing fish protein fertilizer using sludge produced by fish paste processing comprises the following steps:

[0043] S1. The sludge generated during the fish paste processing is initially filtered through a mechanical screen to remove larger solid impurities. The filtered sludge is transported to a sedimentation tank. According to the properties of the sludge, a suitable flocculant (such as polyaluminium chloride, polyacrylamide, etc.) is added to the sludge, and the pH value is adjusted to the isoelectric point. The batch control method is used to control the metering pump to automatically add the drug. By setting the pH meter parameters, the pH of the wastewater is controlled at 4.50-5.00. At the same time, add an appropriate amount of CaCl2, and use Ca2+ to combine with troponin in fish meat to make it lose water and harden, accelerate sinking, and also remove some phosphates in sludge wastewater. Since protein is an amphoteric electrolyte, the number of charges of its charged groups changes according to the color uniformity of the solution. When the protein is at the isoelectric point, the protein molecule exists in the form of zwitterions, and its molecular net charge is zero (i.e., positive and negative charges are equal). At this time, the protein molecule particles in the solution do not have mutual repulsion of the same charge, and the interaction between molecules is weakened. Its particles are very easy to collide, condense and precipitate. Therefore, the protein at the isoelectric point has the lowest solubility and is most likely to form a precipitate. Flocculants are selected and used with cationic polyacrylamide, polyferric sulfate, polyferric silicate, sodium alginate, chitosan, ammonium ferric sulfate, aluminum sulfate, ferric sulfate, aluminum chloride, ferric chloride, and alum. The sludge protein produced by fish paste processing was recovered.

[0044] S2. The flocculant and sludge are fully mixed by the stirring equipment to ensure the flocculation reaction. Under the action of the flocculant and pH adjustment, the suspended matter and protein in the sludge begin to flocculate to form larger flocs, and gradually settle to the bottom of the pool. The supernatant after precipitation can be discharged through the overflow or discharge system, and the precipitated flocs are collected by the scraper or sludge suction equipment;

[0045] S3. Use a sludge pump, scraper or other conveying equipment to transfer the collected sediment to a collection tank, use a sludge dewatering screen or simple dewatering equipment, such as a belt filter press, to perform preliminary dewatering on the sediment, and use an agitator or mixing equipment to stir the sediment at the same time to ensure that its composition is uniform. During this process, the sediment concentration in the collection tank is regularly monitored. When the sludge in the collection tank reaches a certain amount or dehydration degree, it is transferred to the next treatment stage;

[0046] S4. Place the dehydrated and homogenized precipitate in a high-temperature hydrolysis tank and use AS.1398 protease for high-temperature hydrolysis reaction. The temperature of the high-temperature hydrolysis tank is controlled between 180℃ and 200℃, and the pressure is between 4 and 6 MPa. Under this condition, the cell wall and organic structure in the precipitate are destroyed, and soluble organic matter is released. The precipitate after the reaction needs to be cooled quickly to prevent secondary polymerization in the subsequent biodegradation process. The energy for high-temperature hydrolysis is provided by the biogas generated by the high-temperature fermentation tank;

[0047] S5. The hydrolyzed product is transferred to a high-temperature fermentation tank and fermented under aerobic conditions to further decompose organic matter and improve the biological stability of the sludge. A biological deodorant is added during the fermentation process to avoid the generation of odor. The fermented sludge is transported from the fermentation tank to a filter press, and then the sludge is evenly distributed on the filter cloth of the filter press. The water in the sludge is squeezed out by the mechanical pressure of the filter press. The squeezed liquid is collected through the filter cloth and the drainage system of the filter press. The solid particles form a filter cake on the filter cloth. The filter cake after filtration has good dehydration performance and calorific value, which is convenient for subsequent drying and energy utilization. After the filtration is completed, the filter cake is unloaded from the filter press and prepared for the next step of drying. The collected filtrate needs to be further processed to meet the emission standards or recycled. After the filtration operation is completed, the filter press is cleaned to remove the residual sludge to ensure the normal operation of the equipment;

[0048] S6. Transfer the sludge after filtration from the filter press to the drying equipment for drying. The drying equipment uses low-temperature drying equipment, such as a belt dryer, a fluidized bed dryer or a rotary drum dryer. The drying is 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 the drying efficiency. The heat source is the biogas generated during high-temperature fermentation to reduce energy consumption. The temperature, humidity and fluidity of the sludge during the drying process are monitored to ensure uniform drying. The final moisture content of the sludge is controlled 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 the emission standards. The dried sludge is then crushed by crushing equipment;

[0049] S7. Prepare the crushed material for screening. According to the required final particle size and uniformity requirements, select the appropriate screen size and type, put the material into screening equipment such as vibrating screen, drum screen or rotary screen, turn on the screening equipment, make the material vibrate or roll on the screen, collect the fine material passing through the screen, these materials have 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 grinder for re-crushing, while smaller particles fall through the holes of the screen. If more detailed particle size classification is required, it can be achieved through multi-stage screening, using screens of different apertures at each stage, and then the screened materials are sealed and packaged separately to form the final fish protein fertilizer product.

[0050] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for making fish protein fertilizer using sludge produced by minced fish processing, characterized in that: The steps include: S1. Preliminarily filtering the sludge generated during the surimi processing through a mechanical grid, collecting the sludge, adding a flocculant to the sludge, adjusting the pH value to the isoelectric point, and causing protein and other suspended matter to flocculate and precipitate; S2. Separate the solid from the liquid by sedimentation, filtration or centrifugation, and collect the precipitate; S3, placing the collected sediment into a collection tank, and performing preliminary dehydration and homogenization treatment on the sediment; S4, placing the dehydrated and homogenized precipitate in a high temperature hydrolysis tank for high temperature hydrolysis reaction; S5, the hydrolyzed product is transferred to a high-temperature fermentation tank for fermentation under aerobic conditions, and the fermented sludge is transported from the fermentation tank to a filter press for filtration treatment; S6, transferring the sludge after filtration from the filter press to a drying device for drying, and then crushing the dried sludge using a crushing device; S7. The crushed material is sieved to remove particles larger than 200 mesh, and then the sieved materials are sealed and packaged to form the final fish protein fertilizer product.

2. The method for making fish protein fertilizer using sludge produced by minced fish processing according to claim 1, characterized in that: 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.

3. The method for making fish protein fertilizer using sludge produced by minced fish processing according to claim 2, characterized in that: In step S5, the sludge is evenly distributed on the filter cloth of the filter press, and the moisture in the sludge is squeezed out by the mechanical pressure of the filter press.

4. The method for making fish protein fertilizer using sludge produced by fish paste processing according to claim 3, characterized in that: In step S6, before entering the drying stage, the sludge is preheated and dried at a low temperature below 100°C.

5. The method for making fish protein fertilizer using sludge produced by fish paste processing according to claim 4, characterized in that: In step S3, the precipitate is preliminarily dehydrated using a simple dehydration device, and the precipitate is stirred using a stirrer or a mixing device.

6. The method for making fish protein fertilizer using sludge produced by fish paste processing according to claim 5, characterized in that: In step S7, the particles larger than 200 mesh retained on the screen are collected and returned to the pulverizer for re-pulverization, and then the particle size and uniformity of the sieved material are checked.

7. The method for making fish protein fertilizer using sludge produced by minced fish processing according to claim 6, characterized in that: In step S1, the flocculant is one or more of cationic polyacrylamide, polyferric sulfate, polyferric silicate, sodium alginate, chitosan, ammonium ferric sulfate, aluminum sulfate, ferric sulfate, aluminum chloride, ferric chloride, and alum.

8. The method for making fish protein fertilizer using sludge produced by fish paste processing according to claim 7, characterized in that: In step S2, the solid-liquid separation is performed using a vertical flow sedimentation tank, and the fish protein is precipitated in the sedimentation tank.

9. The method for making fish protein fertilizer using sludge produced by minced fish processing according to claim 8, characterized in that: In step S5, the hydrolyzed product is mixed with a microbial agent in a high-temperature fermentation tank for fermentation.

10. The method for making fish protein fertilizer using sludge produced by minced fish processing according to claim 9, characterized in that: All the biogas produced by the high-temperature fermentation is collected by a biogas storage tank, and the biogas storage tank provides energy for the high-temperature hydrolysis tank, the fermentation tank, and the low-temperature drying process.

Images