Segmented flocculation method and device for livestock manure

Abstract

The present application relates to the technical field of excrement treatment, and discloses a livestock and poultry excrement segmented flocculation method and device, which comprises the following steps: pretreatment, coagulation, flocculation growth, densification and separation: first, livestock and poultry excrement is subjected to solid-liquid separation to obtain a stock solution, polyaluminum chloride, strong acid modified vermiculite (flocculant A) and strong alkali modified montmorillonite (flocculant B) are sequentially added, gradient stirring is performed to form dense large flocs, and supernatant and precipitate are separated after standing. The device comprises a flocculation precipitator tank, a water inlet pipeline, a variable frequency stirring motor, a flocculant adding control box and the like, the bottom end of the tank is provided with an anti-blocking structure, and the outer support is provided with a heating structure. The present application improves the excrement treatment efficiency and reduces subsequent load through segmented flocculation and intelligent control, and the precipitate can be recycled. Through the segmented adding design of polyaluminum chloride, strong acid modified vermiculite and strong alkali modified montmorillonite, combined with gradient stirring control, progressive flocculation of strong electric neutralization, adsorption bridging and strong net capture densification is realized.

Description

Technical Field

[0001] This invention relates to the field of manure treatment technology, specifically to a segmented flocculation method and apparatus for livestock and poultry manure. Background Technology

[0002] With the rapid development of large-scale and intensive livestock and poultry farming in my country, the amount of livestock and poultry manure produced has increased dramatically, making its efficient treatment and resource utilization a critical environmental issue that urgently needs to be addressed. Untreated livestock and poultry manure contains high concentrations of organic matter, nitrogen and phosphorus nutrients, suspended solids (SS), and pathogenic microorganisms. Direct discharge or improper disposal can easily lead to eutrophication of water bodies, soil pollution, foul odors in the air, and the spread of diseases, threatening water environment safety and public health.

[0003] Currently, the country encourages the return of livestock and poultry manure to nearby fields. However, most enterprises, especially large-scale intensive farms, lack sufficient land. If all of their manure is returned to nearby fields, they would need to lease nearly 10,000 mu of contiguous planting land, which would significantly increase land transfer costs and enterprise operating expenses. Therefore, meeting emission standards or partially meeting emission standards is still the main choice for most intensive farming enterprises at this stage.

[0004] Livestock and poultry manure, as a complex organic wastewater with extremely high pollutant concentrations, contains high concentrations of suspended solids (SS), colloidal and dissolved organic matter (characterized by COD and BOD), high levels of nitrogen and phosphorus nutrients, various salts, pathogenic microorganisms, and residual veterinary drugs or heavy metals. It is characterized by solid-liquid mixing, high viscosity, strong stability, and significant fluctuations in properties depending on the type of livestock, feed, and manure removal method, making it extremely difficult to treat. High concentrations of organic matter and suspended solids increase the treatment load, colloids and fine particles are difficult to separate effectively, nitrogen and phosphorus removal requires targeted processes, and the variable composition makes single treatment technologies unstable and unsuitable. Furthermore, it is prone to generating foul odors and secondary pollution during treatment. Efficient, stable, and low-cost pretreatment (especially solid-liquid separation) is a key bottleneck for subsequent harmless treatment and resource utilization.

[0005] Flocculation technology is widely used for solid-liquid separation and pretreatment of livestock and poultry manure due to its simple operation, high treatment efficiency, and relatively low cost. The mainstream methods include chemical flocculation, bioflocculation, electroflocculation, magnetic flocculation, and derivative combination technologies, but all of them have shortcomings: PAM crystals commonly used in chemical flocculation are toxic, the treated sludge has a high microplastic content and cannot be composted; bioflocculation and electroflocculation have harsh operating conditions, long cycles, and high costs; magnetic flocculation magnetic powder is difficult to recover and has high operating costs.

[0006] Therefore, the purpose of this invention is to provide a segmented flocculation method and apparatus for livestock and poultry manure to overcome the shortcomings of the prior art. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a segmented flocculation method and apparatus for livestock and poultry manure, which solves the problems of high land costs for returning livestock and poultry manure to nearby fields, low efficiency of existing flocculation technologies, and high load on subsequent treatment in existing livestock and poultry manure treatment.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A segmented flocculation method and apparatus for livestock and poultry manure includes the following steps: S1. Pretreatment step: Solid-liquid separation of livestock and poultry manure is carried out to obtain raw manure liquid to be treated, and the raw manure liquid is sent into the flocculation sedimentation tank through the water inlet pipe; S2, Coagulation step: Polyaluminum chloride is added to the raw fecal waste liquid through the flocculant addition control box and flocculant addition pipe. At the same time, the variable frequency stirring motor is started, and the rotating rod connected to its output end drives the stirring impeller to perform the first stage of stirring, so that the colloidal particles in the fecal waste are destabilized and form micro flocs. S3, Flocculation Growth Step: Subsequently, inorganic flocculant A, which serves as the flocculation core, is added through the flocculant addition control box, and the variable frequency stirring motor drives the stirring impeller to carry out the second stage of stirring. The tiny flocs gradually increase in size through the adsorption bridging effect. S4. Densification step: Next, inorganic flocculant B, which is used to enhance the density of flocs, is added through the flocculant addition control box, and the variable frequency stirring motor drives the stirring impeller to carry out the third stage of stirring to form a dense and easily settled large-sized flocs. Wherein, inorganic flocculant A is strong acid-modified vermiculite, and inorganic flocculant B is strong alkali-modified montmorillonite.

[0009] Preferably, after step S4, a separation step is also included: stopping the stirring of the variable frequency stirring motor, allowing the large-sized flocs formed to settle, separating the supernatant by starting the decanter connected to the supernatant outlet pipe, and separating the precipitate by opening the valve set on the precipitate outlet.

[0010] Preferably, the variable frequency stirring motor is controlled by a controller integrated in the flocculant dosing control box, so that the stirring speed of the first stage of stirring is not greater than 600 r / min, the stirring speed of the second stage of stirring is not greater than 1000 r / min, and is higher than the stirring speed of the first stage of stirring. The stirring speed in the third stage is the same as that in the second stage.

[0011] Preferably, the strong acid-modified vermiculite is prepared by modifying it with a sulfuric acid solution of concentration of 1-4 mol / L at 80-100°C for 2-4 hours.

[0012] Preferably, the strong alkali modified montmorillonite is prepared by modifying it with a sodium hydroxide solution of concentration of 0.5-2 mol / L at 60-90°C for 1-3 hours.

[0013] A segmented flocculation device for livestock and poultry manure includes a flocculation sedimentation tank. An inlet pipe is provided on one side of the external surface of the flocculation sedimentation tank. One end of the inlet pipe is connected to the interior of the flocculation sedimentation tank, and the other end of the inlet pipe is provided with a feed hopper. A variable frequency stirring motor is fixedly installed on the upper part of the flocculation sedimentation tank. A rotating rod is fixedly connected to the output end of the variable frequency stirring motor. Multiple stirring impellers are provided on the outside of the rotating rod. A flocculant dosing control box is also fixedly installed on one side of the upper part of the flocculation sedimentation tank. A flocculant dosing pipe is fixedly connected to one side of the flocculant dosing control box and is connected to the interior of the flocculation sedimentation tank. An external support for the flocculation sedimentation tank is provided on the outside of the flocculation sedimentation tank. The bottom of the flocculation sedimentation tank is equipped with an anti-clogging structure to prevent the processed material from accumulating at the bottom. A heating structure is also fixedly installed on the upper part of the outer support of the flocculation sedimentation tank to heat the inside of the flocculation sedimentation tank, thereby causing the material to fuse.

[0014] Preferably, the flocculation sedimentation tank is further provided with a supernatant outlet pipe for discharging the supernatant, and a sediment outlet for discharging sediment is provided at the bottom of the flocculation sedimentation tank. A valve is provided on the outside of the sediment outlet. One end of the supernatant outlet pipe is connected to a decanter. The decanter is used to skim the supernatant from the surface of the supernatant. The decanter is raised and lowered by an electrically controlled telescopic tube.

[0015] Preferably, the anti-clogging structure includes a filter plate fixedly installed at the bottom of the flocculation sedimentation tank, a plurality of cleaning brushes fixedly installed at the bottom of the rotating rod, the plurality of cleaning brushes being arranged above the filter plate, and a flipping plate being installed on one side of each of the plurality of cleaning brushes at an upward tilt.

[0016] Preferably, the heating structure includes multiple heating elements fixedly installed on the upper part of the outer support of the flocculation sedimentation tank, each of the multiple heating elements is provided with a heat-conducting rod, a heat-conducting ring is provided on the outer side of the flocculation sedimentation tank, the multiple heat-conducting rods are all connected to the heat-conducting ring, and a temperature sensor is provided on the outer side of the flocculation sedimentation tank.

[0017] Preferably, the flocculant dosing control box integrates a controller, which has preset dosing and stirring programs corresponding to the coagulation step, the flocculation growth step, and the densification step.

[0018] This invention provides a segmented flocculation method and apparatus for livestock and poultry manure. It has the following beneficial effects: 1. This invention achieves progressive flocculation through a segmented addition design of polyaluminum chloride, strong acid-modified vermiculite, and strong alkali-modified montmorillonite, combined with gradient stirring control. This results in strong charge neutralization, adsorption, bridging, strong netting, and compaction. In this process, polyaluminum chloride first rapidly neutralizes the colloidal charge to form micro-flocs, and strong acid-modified vermiculite further compacts the flocs, reducing the load on subsequent anaerobic digestion or aerobic treatment. This solves the problems of low treatment efficiency and incomplete pollutant removal in traditional technologies.

[0019] 2. The polyaluminum chloride, strong acid-modified vermiculite, and strong alkali-modified montmorillonite used in this invention are all non-toxic inorganic materials. The heavy metal content of the precipitate produced by flocculation can be directly added to auxiliary materials such as rice bran and mushroom bran for composting, or further processed into organic fertilizer after plate and frame filtration. This realizes the closed-loop utilization of manure treatment precipitate resources, which not only solves the pain point of sludge being difficult to compost in traditional technologies, but also creates additional economic benefits for farms, reduces solid waste disposal costs, and is in line with the policy orientation of resource utilization of livestock and poultry manure.

[0020] 3. This invention integrates a controller with a preset program, which can automatically control the amount of flocculant added and the stirring speed without frequent manual intervention; the anti-clogging structure at the bottom of the tank drives the cleaning brush to clean the filter plate through a rotating rod, and works with the flipping plate to break up the clumps of sediment, preventing blockage at the discharge port; the heating structure on the outer support is linked to the heating element through a temperature sensor to ensure flocculation activity in low-temperature environments, which greatly extends the continuous operation time of the equipment, reduces the frequency of downtime for cleaning, and lowers the overall operating cost, taking into account both equipment stability and economy, and is particularly suitable for the large-scale manure treatment needs of intensive farms. Attached Figure Description

[0021] Figure 1 This is a perspective view of the present invention; Figure 2 This is a schematic diagram of the internal structure of the present invention; Figure 3 This is a schematic diagram of the stirring structure of the present invention; Figure 4 This is a schematic diagram of the segmented flocculation main process sequence control algorithm of the present invention; Figure 5 This is a schematic diagram of the PID isothermal closed-loop feedback control algorithm of the present invention.

[0022] The components include: 1. Inlet pipe; 2. Flocculation sedimentation tank; 3. Variable frequency stirring motor; 4. Flocculant dosing control box; 5. Flocculant dosing pipe; 6. Stirring impeller; 7. Decanter; 8. Decanter electrical control telescopic pipe; 9. Supernatant outlet pipe; 10. Flocculation sedimentation tank external support; 11. Sediment outlet; 12. Feed hopper; 13. Rotating rod; 14. Anti-clogging structure; 1401. Filter plate; 1402. Cleaning brush; 1403. Tilting plate; 15. Heating structure; 1501. Heating element; 1502. Heat-conducting rod; 1503. Heat-conducting ring; 1504. Temperature sensor; 16. Controller; 17. Valve. Detailed Implementation

[0023] The technical solutions in 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.

[0024] Please see the appendix Figure 1 - Appendix Figure 5 This invention provides a segmented flocculation method and apparatus for livestock and poultry manure, comprising the following steps: S1. Pretreatment steps: solid-liquid separation of livestock and poultry manure is carried out to obtain raw manure liquid to be treated, and the raw manure liquid is sent into flocculation sedimentation tank 2 through water inlet pipe 1. S2, Coagulation step: Polyaluminum chloride is added to the raw fecal waste liquid through the flocculant addition control box 4 and the flocculant addition pipe 5. At the same time, the variable frequency stirring motor 3 is started, and the rotating rod 13 connected to its output end drives the stirring impeller 6 to perform the first stage of stirring, so that the colloidal particles in the fecal waste are destabilized and form tiny flocs. S3, Flocculation Growth Step: Subsequently, inorganic flocculant A, which serves as the core of flocculation, is added through the flocculant addition control box 4, and the variable frequency stirring motor 3 drives the stirring impeller 6 to carry out the second stage of stirring. Through the adsorption bridging effect, the tiny flocs gradually increase in size. S4. Densification step: Next, inorganic flocculant B, which is used to enhance the density of flocs, is added through the flocculant addition control box 4, and the variable frequency stirring motor 3 drives the stirring impeller 6 to carry out the third stage of stirring to form a dense and easily settled large-sized flocs. Among them, inorganic flocculant A is strong acid-modified vermiculite, and inorganic flocculant B is strong alkali-modified montmorillonite.

[0025] This embodiment provides a method for preparing strongly acid-modified vermiculite, the specific steps of which are as follows: Raw material pretreatment: Select natural vermiculite, crush it in a pulverizer and pass it through a 200-mesh sieve. Take the powder that passes through the sieve as raw material for later use.

[0026] Acid modification reaction: Weigh 100g of the pretreated vermiculite powder and place it in a reaction vessel. Add 500mL of 2.5mol / L sulfuric acid (H2SO4) solution at a solid-liquid ratio of 1:5 (g / mL). Turn on the mechanical stirrer (300r / min) to evenly disperse the vermiculite powder in the acid solution.

[0027] Isothermal treatment: The reaction system is heated to 90°C and kept at this temperature for 3 hours. During this process, sulfuric acid reacts with metal ions between the vermiculite layers, opening up pores and increasing active sites through acid etching.

[0028] Separation and washing: After the reaction is complete, stop heating and stirring, and allow the mixture to cool to room temperature. Use a vacuum filter to separate the solid and liquid components of the mixture and collect the filter cake. Wash the filter cake repeatedly with deionized water until the pH of the filtrate is neutral (pH 6.5-7.0) to remove residual free acid and reaction byproducts.

[0029] Drying and finished product: The washed filter cake was placed in a forced-air drying oven and dried at 105°C for 12 hours until constant weight. The dried material was then removed, ground, and passed through a 200-mesh sieve again to obtain the inorganic flocculant A (strong acid modified vermiculite).

[0030] This embodiment provides a method for preparing strongly alkali-modified montmorillonite, the specific steps of which are as follows: Raw material pretreatment: Select calcium-based montmorillonite, crush it in a pulverizer and pass it through a 200-mesh sieve. Take the powder that passes through the sieve as raw material for later use.

[0031] Alkali modification reaction: Weigh 100g of the pretreated montmorillonite powder and place it in a three-necked flask. Slowly add 1000mL of 1.0mol / L sodium hydroxide (NaOH) solution at a solid-liquid ratio of 1:10 (g / mL). Turn on the magnetic stirrer and set the stirring speed to 400r / min to prevent the montmorillonite from absorbing water, swelling, settling, and clumping.

[0032] Isothermal treatment: The three-necked flask was placed in a water bath and heated to 80°C, where it was kept at a constant temperature for 2 hours. This process utilizes a strong alkaline solution to etch the montmorillonite lattice, altering its interlayer spacing and surface charge distribution.

[0033] Separation and washing: After the reaction is complete, centrifuge the suspension at 3000 rpm and discard the supernatant. Add deionized water to the precipitate and resuspend, then centrifuge again. Repeat the resuspension, centrifugation and washing steps 3-5 times until the pH of the supernatant is close to neutral (pH 7.0-7.5).

[0034] Drying and finished product: The washed solid material is spread evenly on an enamel tray and placed in a drying oven, where it is dried at 105°C for 10 hours. The dried material is then pulverized and passed through a 200-mesh sieve to obtain the inorganic flocculant B (strong alkali modified montmorillonite).

[0035] Specifically, S1, the pretreatment step: This step is the starting point of the entire process. First, the raw livestock and poultry manure undergoes solid-liquid separation to remove larger solid impurities, thus obtaining the more fluid manure concentrate required for subsequent treatment. Then, this concentrate is pumped through inlet pipe 1 into the flocculation and sedimentation tank 2, which serves as the core reaction vessel. To prevent liquid overflow during subsequent stirring, the feed height is typically controlled at three-quarters of the tank's total volume.

[0036] S2. Coagulation Step: This is the initial stage of the flocculation process. Polyaluminum chloride (PAC) is precisely added to the raw fecal waste solution in the tank via the flocculant addition control box 4 and pipe 5. As a highly efficient inorganic coagulant, PAC releases a large number of positively charged ions that quickly neutralize the negatively charged colloidal particles in the fecal waste. The variable frequency stirring motor 3 drives the stirring impeller 6 to perform high-speed stirring in the first stage. The purpose is to ensure that the agent and the raw fecal waste solution are fully mixed in a short time, ensuring that all colloidal particles come into contact with the coagulant, thereby quickly forming uniform micro-flocculations.

[0037] S3, Flocculation Growth Step: In this stage, inorganic flocculant A, namely strong acid-modified vermiculite, which serves as the flocculation core, continues to be added through flocculant addition control box 4. This connects and aggregates the tiny flocs formed in step S2, causing their volume to gradually increase. Simultaneously, the stirring motor enters the second stage of stirring mode, and its speed changes to adapt to the needs of floc growth, ensuring that the flocs can fully collide and combine while avoiding excessive shear force that could break them up.

[0038] S4. Densification Step: To facilitate floc settling, this step involves adding inorganic flocculant B, namely strong alkali-modified montmorillonite, to enhance density. Strong alkali-modified montmorillonite quickly coats the already grown flocs, filling the gaps between them and increasing their structural strength and density. The stirring motor then enters the third stage of mixing, ultimately forming larger, more compact flocs with increased specific gravity, laying a solid foundation for subsequent rapid solid-liquid separation.

[0039] After step S4, there is also a separation step: stop the stirring of the variable frequency stirring motor 3, let the large-sized flocs formed settle, and separate the supernatant by starting the decanter 7 connected to the supernatant outlet pipe 9, and separate the precipitate by opening the valve 17 set on the precipitate outlet 11. Specifically, this step begins after the densification step S4 is completed and the variable frequency stirring motor 3 has completely stopped working. First, a static settling stage will be entered, allowing the large-sized, high-density flocs formed in S4 to sink naturally under the action of gravity and separate from the clearer liquid above.

[0040] After sedimentation, the supernatant is separated. This is done by activating the decanter 7, which is connected to the supernatant outlet pipe 9. The decanter 7 descends slowly via the electrically controlled telescopic tube 8 at a speed not exceeding 10 cm / min, skimming the supernatant from the surface to avoid disturbing the sediment at the bottom. The decanter automatically stops descending when the turbidity probe on it contacts the sediment layer, ensuring thorough separation.

[0041] After the supernatant is discharged, the sediment is separated. The valve 17, located at the sediment outlet 11 at the bottom of the tank, is opened by program control to discharge the sediment. At this time, the anti-clogging structure 14 at the bottom of the tank will be activated, and the rotating rod 13 will drive the cleaning brush 1402 and the tilting plate 1403 to rotate slowly, breaking up any clumps of sediment and sweeping them to the outlet to ensure smooth discharge without blockage.

[0042] The variable frequency stirring motor 3 is controlled by the controller 16 integrated in the flocculant addition control box 4, so that the stirring speed of the first stage of stirring is no more than 600 r / min and the stirring speed of the second stage of stirring is no more than 1000 r / min, and is higher than the stirring speed of the first stage of stirring. The mixing speed in the third stage is the same as that in the second stage. Specifically, the precise control of this gradient stirring is achieved through a controller 16 integrated inside the flocculant dosing control box 4. This controller 16 has pre-set automation programs corresponding to each step, enabling precise control of the variable frequency stirring motor 3 to output different speeds at different stages.

[0043] The first stage of coagulation and mixing: the mixing speed is set to no more than 600 r / min. This is a relatively high speed, the purpose of which is to generate intense hydraulic turbulence, so as to promote the rapid and uniform dispersion of the agent throughout the water body, so as to fully contact the pollutant particles and achieve rapid destabilization.

[0044] The second stage involves stirring to promote flocculation and growth: the stirring speed is increased to no more than 1000 r / min, and it is explicitly required to be higher than the speed in the first stage. This aims to provide a greater chance of collision for adsorption bridging, thereby accelerating the aggregation and growth of tiny flocs.

[0045] The third stage is densification mixing: the mixing speed is kept the same as in the second stage, not exceeding 1000 r / min. Maintaining a high speed helps the strongly alkali-modified montmorillonite to quickly coat and compact the flocs, forming a dense structure.

[0046] Strong acid modified vermiculite is prepared by modifying it with a sulfuric acid solution of concentration of 1-4 mol / L at 80-100℃ for 2-4 hours.

[0047] Strong alkali modified montmorillonite is prepared by modifying it with a sodium hydroxide solution of concentration of 0.5-2 mol / L at 60-90℃ for 1-3 hours.

[0048] A segmented flocculation device for livestock and poultry manure includes a flocculation sedimentation tank 2. An inlet pipe 1 is installed on one side of the flocculation sedimentation tank 2, with one end connected to the inside of the flocculation sedimentation tank 2 and the other end connected to a feed hopper 12. A variable frequency stirring motor 3 is fixedly installed on the upper part of the flocculation sedimentation tank 2, and a rotating rod 13 is fixedly connected to the output end of the variable frequency stirring motor 3. Multiple stirring impellers 6 are installed on the outside of the rotating rod 13. A flocculant dosing control device is also fixedly installed on one side of the upper part of the flocculation sedimentation tank 2. The flocculant dosing control box 4 is fixedly connected to one side of the flocculant dosing pipe 5, which is connected to the inside of the flocculation sedimentation tank 2. The flocculation sedimentation tank 2 is equipped with an external support 10. The bottom of the flocculation sedimentation tank 2 is equipped with an anti-clogging structure 14, which is used to prevent the processed material from accumulating at the bottom. The upper part of the external support 10 is also fixedly equipped with a heating structure 15, which is used to heat the inside of the flocculation sedimentation tank 2, thereby making the material blend. The flocculation sedimentation tank 2 is also equipped with a supernatant outlet pipe 9 for discharging the supernatant. A sediment outlet 11 for discharging sediment is located at the bottom of the flocculation sedimentation tank 2. A valve 17 is located outside the sediment outlet 11. One end of the supernatant outlet pipe 9 is connected to a decanter 7, which is used to skim the supernatant from the surface. The decanter 7 is raised and lowered via an electrically controlled telescopic pipe 8. The anti-clogging structure 14 includes a filter plate 1401 fixedly installed at the bottom of the flocculation sedimentation tank 2. Multiple cleaning brushes 1402 are fixedly installed at the bottom of the rotating rod 13. All cleaning brushes 1402 are positioned above the filter plate 1401, and each cleaning brush 1402 has an upwardly tilted flap 1403 installed on one side. The heating structure 15 includes multiple heating elements 1501 fixedly installed on the upper part of the outer support 10 of the flocculation sedimentation tank. Each heating element 1501 is provided with a heat-conducting rod 1502. A heat-conducting ring 1503 is provided on the outside of the flocculation sedimentation tank 2. The multiple heat-conducting rods 1502 are all connected to the heat-conducting ring 1503. A temperature sensor 1504 is provided on the outside of the flocculation sedimentation tank 2. The flocculant dosing control box 4 integrates a controller 16. The controller 16 has preset dosing and stirring programs corresponding to the coagulation step, the flocculation growth step, and the densification step.

[0049] Specifically, this invention provides a highly efficient and automated segmented flocculation device for livestock and poultry manure, whose core advantage lies in an intelligent control system integrating advanced control algorithms. The device centers on a flocculation sedimentation tank 2 that integrates reaction and sedimentation, and executes physical and chemical processes through components such as a variable frequency stirring motor 3 and a flocculant dosing control box 4. The core algorithm built into the device is mainly reflected in two aspects. First, a segmented time-series and parameter-coordinated control algorithm precisely governs the entire flocculation process. The controller 16 strictly follows a preset time sequence, instructing the flocculant dosing control box 4 to add specific agents in the three stages of coagulation, flocculation growth, and densification, and simultaneously outputs different frequency signals to the variable frequency stirring motor 3 to achieve gradient stirring. This process strictly follows a slow-to-fast speed-up logic, i.e., the stirring speed in the first stage... r / min, the second stage growth rate reached ,satisfy and r / min, and the third stage maintains .

[0050] The PID-based isothermal valve-loop reaction control algorithm aims to precisely regulate the reaction temperature. The controller 16 continuously monitors the reactant temperature via temperature sensor 1504. and the set target temperature Compare the two and calculate the error between them in real time: ; in, Indicates time Error value at time, This indicates the set target temperature. This indicates the current actual temperature.

[0051] The controller 16 is based on this error The classic PID control algorithm (i.e., proportional-integral-derivative control) is used to intelligently adjust the power of the heating element. The complete expression for its calculation is: ; in, Indicates time Real-time control output, In time Error value at time, Proportional gain constant, Integral gain constant, Differential gain constant, Indicates from time 0 to Error accumulation, Indicates error Rate of change over time.

[0052] Through this algorithm, the controller 16 can predict temperature change trends, effectively suppress temperature overshoot and fluctuations, and smoothly and accurately maintain the reaction system within the optimal temperature range, thereby ensuring the stability and efficiency of the flocculation reaction. In addition, the controller 16 also includes an anti-clogging collaborative operation algorithm. During sludge discharge, it first instructs the variable frequency stirring motor 3 to rotate at low speed to activate the cleaning brush 1402 in the anti-clogging structure 14, stirring the sediment. Then, it opens the valve 17. Through the sequential coordination of these actions, the problem of high-solids-content materials clogging the outlet is solved.

[0053] In this embodiment, the inorganic flocculant A is strong acid-modified vermiculite, and the inorganic flocculant B is strong alkali-modified montmorillonite. The preparation methods are as follows: Preparation method of inorganic flocculant A: The drug appears as yellowish-white granules and is prepared using ultrasound-microwave synergistic enhancement technology. The specific steps are as follows: (1) Precursor preparation: Pre-dried (80-100℃, 30-60min) ferrous sulfate and ferric sulfate powders were mixed according to Fe... 2+ :Fe 3+ Mix in a molar ratio of 1.5:1. First, dissolve ferrous sulfate in ultrapure water containing 0.1-0.3% ascorbic acid, then dissolve ferric sulfate in ultrapure water containing 0.05-0.15% hydroxyethylidene diphosphonic acid (a structure-directing agent). Both solutions are then ultrasonically treated separately at 200-400W before mixing to achieve a total Fe concentration of 10-15%.

[0054] (2) Ultrasonic-Microwave Synergistic Hydrolysis: The mixture was placed in a composite reactor. Ultrasonic (20-40kHz, 300-600W) and microwave (2450MHz, 500-1000W) were activated, and the temperature was increased to 65-75℃ at a rate of 5℃ / min. Oxygen microbubbles (<100μm) were introduced for in-situ oxidation until Fe... 2+ Conversion rate reaches 30-50%.

[0055] (3) Intelligent pH gradient controlled polymerization: A composite alkalizing agent (NaOH + Na2CO3 + a small amount of polyacrylamide) is added dropwise using an intelligent pH feedback system. The pH is controlled to rise in three stages: 2.5-3.0 → 3.5-4.0 → 3.8-4.3. At the same time, the microwave power is increased to 800-1200W (pulse mode), the ultrasonic power is adjusted to 400-800W, the temperature is 80-95℃, and the polymerization time is 1.5-3 hours.

[0056] (4) Frequency conversion curing and separation drying: Stop heating and perform frequency conversion ultrasonic curing (20-60kHz periodic change) at 70-80℃, adding sodium silicate stabilizer. After curing, program the temperature to drop, then centrifuge at high speed and filter through a 0.45μm membrane. Finally, spray dry (inlet air 150-200℃) or freeze dry (-20℃ to 0℃ sublimation), and then screen out 1-2mm particles by air jet milling to obtain the final product.

[0057] Preparation method of inorganic flocculant B: The reagent appears as grayish-white granules and is prepared using a magnetic field-assisted dynamic rheological control technique. The specific steps are as follows: (1) Silicon source activation: Take sodium silicate with a modulus of 3.0-3.8, prepare an 8-18% SiO2 solution, add 0.05-0.2% silane coupling agent, and then dissolve it by ultrasound and pretreat it with ultraviolet ozone. A two-stage dissolution (room temperature / high temperature) and mixing method is adopted to ensure complete activation of the monomer.

[0058] (2) Magnetic field-directed acidification: Under a helical magnetic field with a magnetic induction intensity of 0.3-0.8T, a composite acidifying agent (hydrochloric acid + buffer or CO2 microbubbles) is added dropwise to the sodium silicate solution. Four-stage pH control is performed (11.0→9.5→8.5→7.8→7.2), and the viscosity is monitored in real time using an online rheometer (controlled at 15-50 mPa·s) to prevent gelation.

[0059] (3) Microwave and ultrasonic synergistic polymerization and crosslinking: Start microwave (600-1000W pulse) and ultrasonic (300-600W) and program the temperature to 75℃. Add crosslinking enhancer in batches: add aluminum salt (PAC) in the early stage, add borate in the middle stage, and add rare earth modifier (lanthanum nitrate / cerium) in the later stage to construct a multi-element crosslinking network.

[0060] (4) Dynamic aging and post-treatment: A variable temperature aging program (50℃→30℃→15℃) was adopted, during which periodic high-shear dispersion was performed. After aging, the pH was adjusted to 6.8-7.5. The solution was concentrated by nanofiltration (1000-5000 Da cutoff) and desalted by reverse osmosis. Finally, the product was obtained by freeze drying or low-temperature spray drying, chitosan / nano-SiO2 microcapsule encapsulation, and air-jet fractionation.

[0061] Using the flocculation sedimentation tank 2 of the present invention, in conjunction with the flocculant prepared above, livestock and poultry manure is treated: Control Phase 1 (Coagulation): After the water enters the system, the controller instructs the dosing tank 4 to add inorganic flocculant A. Because this flocculant possesses a directional three-dimensional structure co-constructed by ultrasound and microwaves, it rapidly neutralizes the colloidal charge of the fecal matter under the medium-speed stirring of motor 3, forming micro-flocs.

[0062] Phase Two (Denseization): The controller instructs the addition of inorganic flocculant B. Because this flocculant is a highly polymerized chain molecule grown under magnetic field guidance and contains aluminum / boron / rare earth multi-element crosslinking points, under the low-speed stirring of motor 3, it strongly traps and adsorbs the micro-flocs, forming large and dense flocs.

[0063] Performance data: The COD removal rate of the supernatant discharged through decanter 7 is more than 20% higher than that of commercially available ordinary agents, the water content of the precipitate is reduced by 15%, and due to the anti-gelling properties of the flocculant, there is no clogging during the sludge discharge process.

[0064] Working principle: First, the livestock and poultry manure undergoes pretreatment with solid-liquid separation to remove coarse impurities, resulting in raw manure liquid to be treated. The raw liquid is transported through the inlet pipe 1 to the flocculation sedimentation tank 2, which is installed on the outer support 10 of the flocculation sedimentation tank. The feed height is controlled at three-quarters of the tank to prevent liquid overflow during subsequent stirring. At this time, the controller 16 integrated in the flocculant dosing control box 4 starts the preset program, first entering the coagulation step: the controller 16 instructs the flocculant dosing control box 4 to add 13% PAC solution into the tank through the flocculant dosing pipe 5 at a rate of 1.3 kg / m³ of manure. At the same time, the variable frequency stirring motor 3 is started, and the rotating rod 13 connected to its output end drives the stirring impeller 6 to perform the first stage of stirring at a speed not exceeding 600 r / min. The aluminum ions released by PAC quickly neutralize the negative charge of colloidal particles in the manure, causing the colloids to destabilize and form micro flocs.

[0065] After the coagulation step lasts for 3 minutes, the device automatically enters the flocculation growth step: the controller 16 adjusts the flocculant addition control box 4, adding 13% inorganic flocculant A at a rate of 2.6 kg / m³ of manure, while simultaneously increasing the speed of the variable frequency stirring motor 3 to no more than 1000 r / min for the second stage of stirring. Strong acid-modified vermiculite, with its porous structure and charge characteristics, gradually connects the tiny flocs through adsorption bridging, promoting floc volume increase. During this process, the heating structure 15 on the outer support 10 of the flocculation sedimentation tank works synchronously, and the temperature sensor 1504 monitors the manure temperature inside the tank in real time. If the temperature is below 15℃, multiple heating elements 1501 are triggered, and heat is transferred through the heat-conducting rod 1502 to the heat-conducting ring 1503 on the outside of the tank, and then evenly conducted into the tank, maintaining the manure temperature at 20-25℃ to ensure the adsorption activity of flocculant A and prevent slow floc growth due to low temperatures.

[0066] After the flocculation growth step lasts for 3 minutes, the densification step begins: Controller 16 continues to instruct the flocculant addition control box 4 to add 13% inorganic flocculant B at a rate of 2.6 kg / m³ of manure. The variable frequency stirring motor 3 maintains a speed not exceeding 1000 r / min for the third stage of stirring. Strong alkali-modified montmorillonite has a strong trapping ability, quickly encapsulating the enlarged flocs, filling the gaps between the flocs, and enhancing structural stability, ultimately forming dense and easily settling large-sized flocs. After stirring for 5 minutes, the variable frequency stirring motor 3 stops working, and the device enters a 10-minute settling stage.

[0067] After settling, the separation process begins: Controller 16 controls the decanter's electrically controlled telescopic tube 8 to descend the decanter 7 at a speed not exceeding 10 cm / min. The turbidity probe on the decanter 7 detects the liquid turbidity in real time. When the probe contacts the sediment layer, the telescopic tube immediately stops descending, and the supernatant is discharged through the supernatant outlet pipe 9 via the decanter 7 and enters the subsequent treatment system. Five minutes after decanting, controller 16 opens the valve 17 outside the sediment outlet 11. At this time, the anti-clogging structure 14 at the bottom of the tank comes into play. Multiple cleaning brushes 1402 at the bottom of the rotating rod 13 rotate slowly with the rotating rod 13 to clean the sediment accumulated on the surface of the filter plate 1401. At the same time, the upward-tilting flipping plate 1403 on one side of the cleaning brush 1402 breaks up the clumps of sediment, preventing the sediment from clogging the filter plate 1401 and the outlet, ensuring smooth discharge of the sediment. The discharged sediment can be directly composted with auxiliary materials such as rice bran and mushroom bran, or further processed after plate and frame filtration. Once the sediment is completely discharged, the inlet pipe 1 is restarted to begin the next batch of manure treatment process. The entire process is fully automated and intelligently controlled, requiring no frequent manual intervention. This ensures flocculation efficiency and, through the use of non-toxic agents and resource recovery design, broadens the utilization pathways of manure treatment residues and reduces overall operating costs.

Claims

1. A segmented flocculation method for livestock and poultry manure, characterized in that, Includes the following steps: S1. Pretreatment steps: solid-liquid separation of livestock and poultry manure is carried out to obtain raw manure liquid to be treated, and the raw manure liquid is sent into the flocculation sedimentation tank (2) through the water inlet pipe (1); S2, Coagulation step: Polyaluminum chloride is added to the original sewage liquid through the flocculant addition control box (4) and the flocculant addition pipe (5). At the same time, the variable frequency stirring motor (3) is started, and the rotating rod (13) connected to its output end drives the stirring impeller (6) to carry out the first stage of stirring, so that the colloidal particles in the sewage are destabilized and form micro flocs. S3, Flocculation Growth Step: Subsequently, inorganic flocculant A, which serves as the core of flocculation, is added through the flocculant addition control box (4), and the variable frequency stirring motor (3) drives the stirring impeller (6) to carry out the second stage of stirring, so that the tiny flocs gradually increase in size through the adsorption bridging effect. S4, Densification step: Next, inorganic flocculant B for enhancing the density of flocs is added through the flocculant addition control box (4), and the variable frequency stirring motor (3) drives the stirring impeller (6) to carry out the third stage of stirring to form a dense and easily settled large-sized flocs. Wherein, inorganic flocculant A is strong acid-modified vermiculite, and inorganic flocculant B is strong alkali-modified montmorillonite; The variable frequency stirring motor (3) is controlled by the controller (16) integrated in the flocculant addition control box (4), so that the stirring speed of the first stage stirring is no greater than 600 r / min, the stirring speed of the second stage stirring is no greater than 1000 r / min, and is higher than the stirring speed of the first stage stirring; the stirring speed of the third stage stirring is the same as the stirring speed of the second stage stirring.

2. The segmented flocculation method for livestock and poultry manure according to claim 1, characterized in that, After step S4, also The separation steps include: stopping the stirring of the variable frequency stirring motor (3), allowing the large-sized flocs to settle, separating the supernatant by starting the decanter (7) connected to the supernatant outlet pipe (9), and separating the precipitate by opening the valve (17) set on the precipitate outlet (11).

3. The segmented flocculation method for livestock and poultry manure according to claim 1, characterized in that, The strong acid-modified vermiculite was prepared by modifying it with a sulfuric acid solution of 1-4 mol / L at 80-100℃ for 2-4 hours.

4. The segmented flocculation method for livestock and poultry manure according to claim 1, characterized in that, The strong alkali modified montmorillonite is prepared by modifying it with a sodium hydroxide solution of concentration of 0.5-2 mol / L at 60-90℃ for 1-3 hours.

5. A segmented flocculation device for livestock and poultry manure, employing the segmented flocculation method for livestock and poultry manure as described in any one of claims 1-4, characterized in that, The system includes a flocculation sedimentation tank (2), an inlet pipe (1) on one side of the flocculation sedimentation tank (2), a feed hopper (12) at the other end of the inlet pipe (1), one end of the inlet pipe (1) being connected to the inside of the flocculation sedimentation tank (2), a variable frequency stirring motor (3) fixedly installed on the upper part of the flocculation sedimentation tank (2), a rotating rod (13) fixedly connected to the output end of the variable frequency stirring motor (3), multiple stirring impellers (6) on the outside of the rotating rod (13), a flocculant dosing control box (4) fixedly installed on one side of the upper part of the flocculation sedimentation tank (2), a flocculant dosing pipe (5) fixedly connected to one side of the flocculant dosing control box (4), the flocculant dosing pipe (5) being connected to the inside of the flocculation sedimentation tank (2), and a flocculation sedimentation tank support (10) on the outside of the flocculation sedimentation tank (2). The bottom of the flocculation sedimentation tank (2) is provided with an anti-clogging structure (14) for placing the processed material to accumulate at the bottom. The upper part of the outer support (10) of the flocculation sedimentation tank is also fixedly installed with a heating structure (15) for heating the inside of the flocculation sedimentation tank (2) so that the material can be fused.

6. A segmented flocculation device for livestock and poultry manure according to claim 5, characterized in that, The flocculation sedimentation tank (2) is also provided with a supernatant outlet pipe (9) for discharging supernatant. The bottom end of the flocculation sedimentation tank (2) is provided with a sediment outlet (11) for discharging sediment. A valve (17) is provided on the outside of the sediment outlet (11). One end of the supernatant outlet pipe (9) is connected to a decanter (7). The decanter (7) is used to skim off the supernatant from the surface of the supernatant. The decanter (7) is raised and lowered by the decanter's electrically controlled telescopic pipe (8).

7. A segmented flocculation device for livestock and poultry manure according to claim 5, characterized in that, The anti-clogging structure (14) includes a filter plate (1401) fixedly installed at the bottom of the flocculation sedimentation tank (2), and a plurality of cleaning brushes (1402) fixedly installed at the bottom of the rotating rod (13). The plurality of cleaning brushes (1402) are all arranged above the filter plate (1401), and a flipping plate (1403) is installed on one side of each of the plurality of cleaning brushes (1402) at an upward tilt.

8. A segmented flocculation device for livestock and poultry manure according to claim 5, characterized in that, The heating structure (15) includes multiple heating elements (1501) fixedly installed on the upper part of the outer support (10) of the flocculation sedimentation tank. Each of the multiple heating elements (1501) is provided with a heat-conducting rod (1502). A heat-conducting ring (1503) is provided on the outside of the flocculation sedimentation tank (2). Each of the multiple heat-conducting rods (1502) is connected to the heat-conducting ring (1503). A temperature sensor (1504) is provided on the outside of the flocculation sedimentation tank (2).

9. A segmented flocculation device for livestock and poultry manure according to claim 5, characterized in that, The flocculant dosing control box (4) integrates a controller (16), which has a preset dosing program and stirring program corresponding to the coagulation step, the flocculation growth step and the densification step.

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