Talking about the technology and equipment of livestock and poultry manure composting to produce organic fertilizer

It is more suitable to produce organic fertilizer through aerobic composting of livestock and poultry manure. The traditional composting and fermentation of livestock and poultry manure is mainly based on natural fermentation, which has disadvantages such as long cycle, incomplete fermentation, large pollution, and heavy odor. The production of organic fertilizer by pure manpower is labor-intensive, harsh working environment, and low labor efficiency, which is difficult to adapt to. The current social development situation of high labor costs and efficient production is also difficult to adapt to the development of modern ecological cycle agriculture and efficient animal husbandry. Therefore, it will become particularly necessary to improve the level of organic fertilizer production equipment.

  1. Composting technology

Livestock and poultry manure is generally treated in two forms: liquid manure and solid manure. The treatment methods of liquid manure include anaerobic fermentation technology and natural biological treatment technology, and the main treatment method of solid manure is composting. Composting refers to the process of mineralizing, humifying, and harmless (killing pathogenic bacteria, insect eggs, weed seeds, etc.) of organic matter through high-temperature fermentation under the action of microorganisms to become decomposed fertilizer.

The whole process can be summed up into three links: raw material pretreatment, aerobic fermentation, and granulation. Raw material pretreatment includes solid-liquid separation, auxiliary material pulverization, and adjustment of raw material moisture content, carbon-nitrogen ratio, and pH value. The aerobic fermentation process includes tossing and ventilation

and other measures to supplement oxygen, control temperature, dissipate moisture and restore porosity to raw materials. Pellet molding is a systematic project. Around the core of granulation and molding, there are crushing, batching, mixing and other processes before, followed by drying, screening, cooling and other processes.

  1. Raw material pretreatment and equipment

Raw material pretreatment is mainly to prepare fermentation raw materials that meet the requirements of aerobic fermentation. The main process includes solid-liquid separation of livestock manure, crushing of auxiliary materials and mixing ratio of various raw materials.

2.1 Solid-liquid separation equipment

The raw material for composting is solid manure. The source of solid feces is dry clean feces and solids separated from “bubble feces” by solid-liquid separation method. To achieve solid-liquid separation, the most widely used separation effect is mechanical separation. Mechanical separation equipment can be divided into 4 types: screening separation, centrifugal separation, filter press separation and screw extrusion separation.

1) Screening and separation machinery: The screening machinery used for the separation of livestock and poultry manure mainly includes inclined plate screen and vibrating screen. The cross-sectional shape of the screen bar is a wedge-shaped inclined plate screen, which is used for the separation of feces and has the characteristics of simple structure and no blockage. However, the solid matter removal rate is low, generally

less than 25%.

2) Centrifugal separation machinery: The centrifugal solid-liquid separators used for livestock and poultry manure mainly include filter centrifuges and horizontal screw centrifuges. The advantages of centrifugal separators are fast separation speed and high separation efficiency, but the disadvantages are large investment, complex structure and high energy consumption.

3) Filter press separation machinery: The filter press has the advantages of large processing capacity, simple operation and management, low moisture content of the filter cake, no vibration, no noise, and low energy consumption. Because the filter belt is used to separate the solid and the liquid, in order to prevent the filter belt from clogging, high-pressure water needs to be continuously washed, which increases the sewage treatment volume and costs high.

4) Screw extrusion separation machinery: The screw extrusion separator is a relatively new type of solid-liquid separation equipment, and is currently the most widely used equipment for solid-liquid separation of livestock and poultry manure. The disadvantage is that the raw manure water needs to be stirred evenly with a stirrer before separation, so that a large amount of solid organic matter in the manure water is dissolved in the water, making the post-treatment of the waste water extremely difficult, and the final treated effluent is difficult to meet the discharge standard.

In view of some existing deficiencies, a new type of solid-liquid separator can be researched and designed, the separation mechanism can be improved, the fecal liquid can be prevented from directly rushing into the separation system, the anti-blocking property of the screen can be enhanced, the working efficiency and separation effect of the equipment can be greatly improved, and the reduction of Solid moisture content.

2.2 Crushing equipment

The fermentation process of livestock and poultry manure requires the addition of certain auxiliary materials (straw, branches, rice husks, corn cob, etc.). In order to obtain the particle size of the auxiliary materials suitable for aerobic composting fermentation, the auxiliary materials need to be pulverized, so pulverization equipment is required. There are mainly three kinds of equipment for commonly used material crushing: hammer crusher, large and small guillotine, and branch crusher. The hammer mill has good versatility. When working, the material enters the pulverizing chamber from the feeding port. First, the hammer is driven by the high-speed rotating rotor to strike and rub it, and then it is further affected by the sieves and teeth set around the pulverizing chamber. The impact and rubbing action of the plate realizes the crushing process. When the particle size of the material is smaller than the sieve hole diameter of the sieve, it is discharged from the discharge port through the sieve. The waste after grain processing, such as rice husks, corn cob, etc., can be passed through a hammer mill to achieve satisfactory results. The shredding machine is powered by an electric motor or an internal combustion engine. The power is transmitted to the main shaft, and the gear at the other end of the main shaft transmits the speed-regulated power to the grass pressing roller through the gear box, universal joint, etc. When the material to be processed enters between the upper and lower grass pressing rollers, it is clamped by the grass pressing roller. It is held and fed into the guillotine cutting mechanism at a certain speed. The straw after the crop is harvested can be cut and crushed by a guillotine machine to obtain a satisfactory particle size because it contains long fibers. The branch crusher uses the high-speed relative motion between the movable toothed disc and the fixed toothed disc, and the crushed objects are crushed by the comprehensive action of tooth impact, friction and impact between objects, and the crushed objects can be directly passed through the grinding chamber of the main machine.

The particle size is obtained by replacing mesh screens with different apertures. All kinds of wood, wood scraps, branches and branches, etc. can be crushed by the branch crusher.

The improvement of crushing equipment can start from rationally optimizing the cutting angle of the fixed knife, optimizing the cutting speed of the cutter head, the blade parameters and the arrangement of the blades and hammers on the cutter head, so that the crushing mechanism can quickly cut and rub a variety of materials. At the same time, increase the research on the feeding mechanism to solve the problem of difficult feeding and difficult to enter the crushing cavity.

2.3 Mixing equipment

Mixing refers to the process of uniformly mixing solid feces, auxiliary materials and various conditioners according to the preset formula ratio. Pre-mixing the raw materials can make the required carbon-nitrogen ratio everywhere in the heap to ensure the survival and reproduction of microorganisms. According to the nature of the material to be mixed, it is advisable to use a double-shaft gravity-free mixer. The horizontal simplified machine is equipped with double-shaft rotating and reversed paddles. The paddles are at a certain angle to circulate and stir the materials along the axial and radial directions, so that the materials can be mixed quickly and evenly. The rotation speed of the drive shaft of the reducer and the structure of the paddle will weaken the gravity of the material. Even if the material has a difference in specific gravity and particle size, it can achieve a good mixing effect under the rapid and violent tossing and throwing of the staggered stirring blades. If the machine can automatically control the mixing time according to the properties of the raw materials, better results and efficiency can be achieved.

  1. Fermentation equipment

The fermentation methods of livestock manure to make organic fertilizer include: stack-type fermentation, trough-type fermentation, and tower heating-type fermentation. The strip-stack fermentation is a relatively primitive fermentation method, with a long fermentation period, a general fermentation effect, and a large area, but the production process is simple, the equipment debugging is convenient, and the cost is low. Tank fermentation has strong controllability, can effectively shorten the fermentation period, and has good fermentation effect, but the civil construction cost is relatively high, the equipment often needs to be customized, and the installation cost is high. The tower body heating fermentation has stable sealing performance, strong mobility, and good fermentation effect. The cycle is generally within one week, but the equipment investment cost is high.

3.1 stacking fermentation equipment

The stack-type fermentation equipment mainly refers to the stack-type stacker. The strip stacker is a kind of turning and throwing equipment suitable for strip stack fermentation, which generally requires a larger site. The strip-stack fermentation is to stack the materials into strips of a certain height, without the need to build a fermentation tank. Compost fermentation. The stack-type stacker is mainly composed of a turning device, a walking driving tractor, a transmission system, etc., and is mainly driven by an internal combustion engine. Due to the low stacking height of the material, the stacking type fermentation has a poor heating effect. Due to outdoor accumulation and fermentation, it is easily affected by seasons and rainy days. In addition, its exhaust pollution, odor and water seepage will bring environmental problems. The strip stacker is more suitable for the pretreatment of adhesive materials, small-scale production, farm self-use fertilizer production, no fixed production site or temporary production. The strip stacker turner should increase the research on the self-adaptation of the stacking height, so that the equipment has the self-adaptive control function and enhance the ability of the equipment to adapt to the material. Since it is a manned device, it should be equipped with a cockpit with air conditioning and air filtration and purification system, which is conducive to improving the working environment.

3.2 Tank fermentation equipment

The trough fermentation equipment mainly refers to the trough flipping machine. The trough turning machine is a turning equipment matched with the fermentation tank. Tracks are installed on the tops of both sides of the fermentation tank, and the turner can run back and forth on the tracks. Generally, the trough type turning machine is equipped with one machine with multiple troughs, and the transfer of the turning machine between the fermentation tanks can be realized by the transfer machine. The trough turning machine is mainly composed of a frame, a turning device, a traveling mechanism, a cable reel device, an electric control system, etc., and is mainly driven by electric power. The trough fermentation system has the advantages of small footprint, high composting depth (0.8~2.5 m), fast temperature rise and large processing capacity. It is widely used in China and is the main turning equipment for livestock and poultry manure composting in my country. In the process of tank fermentation, it can maintain and ensure the alternating state of medium temperature – high temperature – medium temperature – high temperature, and effectively shorten the fermentation period. A device for adding bacteria is installed on the turning machine, which can be sprayed evenly and proportionally during the fermentation process. At the same time, a ventilation pipe can be laid at the bottom of the tank to increase the ventilation volume. There are also equipment using electricity, no exhaust pollution, odor and water seepage can also be effectively controlled. The trough type turning and polishing machine is suitable for refined and large-scale production, which is conducive to production management and production cost control.

The trough turning machine can be improved and studied in the aspects of walking safety, reliability of turning system, adaptability to composting materials and automation degree of operation. The product is produced with high efficiency, stable and reliable operation, sturdy and durable, and evenly flipping, which is well received by the market.

3.3 Tower heating fermentation equipment

The tower heating fermentation equipment adopts closed operation. The livestock and poultry manure, auxiliary materials, bacterial agents and reflux materials are mixed uniformly according to a certain proportion, so that the moisture content reaches the requirement of 60%~65%, and then enters the three-dimensional aerobic system. Carry out sufficient aerobic fermentation and decomposition, the heat released during the decomposition process can increase the temperature of the material itself, the highest temperature can reach 80 ° C, the moisture in the material is evaporated with the increase of temperature, and part of the organic matter is decomposed, so that the material pile The volume is reduced, and the reduction of the material is reached. The equipment can be equipped with detection and control devices, which can realize precise control of different fermentation stages in the fermentation process, which is beneficial to the reproduction, expansion, fermentation and decomposition of livestock and poultry manures of target organisms. Auxiliary heating of the equipment ensures proper operation in low temperature environments. However, the fermentation tower has high requirements for production materials and correspondingly high manufacturing costs. Moreover, it is also equipped with automatic detection and control devices, and the maintenance costs are also high. In order to achieve rapid development of tower fermentation equipment, efforts should be made to reduce prices, realize convenient operation, good maintenance and low energy consumption.

  1. Pelletizing and forming equipment

Granulation molding is a unique link in China compared to Europe and the United States. Granular fertilizers have good commodity properties, and they will not be automatically graded during storage and transportation. They have slow-release properties and can create agglomerate structure for soil. At present, the main organic fertilizer granulation methods on the market mainly include extrusion granulation and agglomeration granulation. The commonly used equipment for extrusion granulation is the counter-roll extrusion granulator, which is the most widely used granulator in the organic fertilizer granulator. The material is added from the feed hopper, extruded by the rollers, demolded to form a ball, and then sent to the crushing screen working room to screen and separate the finished particles, and then the returned material is mixed with the new material, and then granulated. In addition, extrusion granulation equipment includes flat die granulator and ring die granulator. Commonly used equipment for agglomeration and granulation is disc granulator and drum granulator. The disc granulator is a mature organic fertilizer granulation equipment. The angle of the granulation disc adopts an overall arc structure. The material entering the disc is sprayed with an appropriate amount of liquid by the atomizing nozzle, and is rotated by the granulation disc to make The finished particles are formed into a certain amount and then thrown out with the inertia of the disc rotation. The granulation tray is equipped with three discharge ports, which is convenient for intermittent production operations. There is a special structure inside the drum body of the drum granulator. The material to be granulated is passed through the rotary motion of the drum body to generate rolling rotation in the simplified body, and aggregate into balls under a certain humidity and temperature to complete the ball making process.

Drying and cooling are generally required after granulation. Common drying equipment includes drum dryer, fluidized bed dryer, airflow dryer, etc. At present, drum dryers are used more. If it is a bio-organic fertilizer, it is generally limited by the bacterial agent to choose low-air volume multi-stage low-temperature drying. The granulating and forming equipment can be added with a drying module and a cooling module, making it a multi-functional integrated machine, which can simplify the process flow and save equipment costs.