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Powdered organic fertiliser occupies an important position in the organic fertiliser market due to its advantages of low production cost, ease of use and balanced fertiliser effect. In this paper, the production process of powdered organic fertiliser will be discussed in depth, including raw material selection, production process, equipment use and quality control, etc., to provide detailed references for organic fertiliser producers and agricultural practitioners.
What is powdered organic fertiliser?
Concept of powdered organic fertiliser
Powdered organic fertiliser refers to powdered organic fertiliser made from organic raw materials after fermentation, crushing, drying and other treatment processes through physical or chemical methods. Compared with granular or liquid organic fertiliser, powdered organic fertiliser is more suitable for large-scale spreading, and the production process is relatively simple, saving the granulation and other processes, so the cost is lower.
Selection of raw materials for powdered organic fertiliser
Animal manure
Livestock manure such as pig manure, chicken manure and cow manure are rich in basic fertiliser components such as nitrogen, phosphorus and potassium, and are one of the main raw materials for the production of powdered organic fertiliser. However, these manures may also contain harmful substances such as pathogenic bacteria, parasite eggs, etc., so they need to undergo harmless treatment, such as composting and fermentation, high temperature disinfection, etc., before use.
Crop straw
Crop straws such as straw, rice straw, corn stover and so on contain a large amount of carbon and can provide soil organic matter. The straw can be crushed and then fermented, which can be converted into high-quality organic fertiliser raw materials.
Food waste
Food waste is rich in organic matter and can be used as one of the high quality raw materials for organic fertiliser. However, food waste contains high levels of moisture and impurities and must be crushed, dehydrated and screened for impurities before it can be used.
Food Processing Waste
Food processing wastes such as sugar factory waste, beer dregs, sauce residue, etc. are rich in organic substances and trace elements. These wastes can also become raw materials for powdered organic fertiliser after proper treatment.
Municipal sludge
Municipal sludge after harmless treatment can also be used as raw material for organic fertiliser. However, sludge contains a high level of heavy metals and pathogens, and must undergo rigorous high-temperature disinfection and heavy-metal-removal treatment to ensure that it is safe and harmless.
Nutritional composition of powdered organic fertiliser
The main nutrients of powdered organic fertiliser include macronutrients such as nitrogen, phosphorus and potassium, and it also contains rich organic matter, humus and a variety of microelements such as calcium, magnesium, sulphur, zinc and copper. These nutrients can be gradually decomposed in the soil and absorbed by the plant root system, which plays a long-term effective fertiliser effect. At the same time, organic matter and humus can also improve soil structure, improve soil fertility and water retention capacity.
Production process of powdered organic fertiliser
Raw material collection and handling
Livestock and poultry manure treatment
Livestock manure needs to be dewatered using a liquid separator to reduce the moisture content in the raw material for subsequent fermentation. Dewatered livestock manure should be stored in a well-ventilated area to avoid secondary contamination.
Crop residue treatment
Crop straw is drier and needs to be processed into smaller particles using a straw crusher to increase its surface area for fermentation and improve fermentation efficiency.
Disposal of food waste and food processing waste
These raw materials contain a lot of moisture and impurities. Firstly, food waste and food processing waste are crushed using a wet material crusher to reduce the particle size. Then, excess water is removed using dewatering equipment to reduce the moisture content to a suitable range. Finally, impurities such as plastics and metals are removed by screening equipment.
Municipal sludge treatment
Municipal sludge contains high levels of heavy metals and pathogens and must be treated with high-temperature disinfection and heavy metal removal to ensure that it is safe and harmless. High-temperature steam disinfection and chemical treatment can be used to remove pathogens, while physical or chemical methods are used to remove heavy metals from sludge.
Fermentation process
Palletised fermentation
The treated raw materials are stacked into pallets, and through natural ventilation or artificial turning of the pile, the raw materials are in full contact with the air, so as to carry out aerobic fermentation. During the fermentation process, attention should be paid to controlling the temperature, humidity and ventilation conditions. Generally speaking, the temperature rises quickly at the beginning of fermentation, reaching 50 – 60 degrees Celsius, and then gradually decreases. Humidity should be controlled between 50% – 60%, too high humidity will affect the fermentation effect, too low humidity will easily lead to stagnation of fermentation. Stack fermentation usually takes about 7 – 15 days.
Tank fermentation
The raw materials are put into the fermentation tank, and the suitable fermentation environment is provided by the mixing and ventilation equipment of machine composter, and the fermentation time is relatively short, about 5-10 days. Fermentation tanks are generally made of concrete or steel structure, with a certain depth and width, which is convenient for stacking and fermentation of raw materials. During tank fermentation, it is important to ensure that the ventilation equipment operates properly to ensure oxygen supply and uniform temperature inside the heap.
Crushing process
After fermentation of organic fertiliser raw materials need to be crushed to get fine, uniform particles of powdered fertiliser. Crushing equipment generally choose high-efficiency crusher, can be crushed to more than 40 mesh fineness of the material. In the crushing process, attention should be paid to avoid excessive crushing caused by excessive fertiliser dust.
Drying process
The crushed organic fertiliser still contains a certain amount of moisture, and usually needs to be further dried to a moisture content of less than 15% for storage and use. Drying equipment is generally used rotary dryer or flash dryer, drying temperature control at 80 – 100 degrees Celsius. During the drying process, the material should be turned evenly to ensure uniform drying and prevent localised overheating or over-wetting.
Packaging & Storage
Powdered organic fertiliser can be packed directly after drying is completed. Packaging materials usually choose plastic bags with good moisture-proof performance to avoid the fertiliser from moisture caking in the storage process. After packing, the organic fertiliser needs to be placed in a dry, well-ventilated warehouse to prevent the influence of direct sunlight, humid environment and harmful gases. The storage time should not exceed one year, so as not to affect the quality and effectiveness of organic fertiliser.
Quality control of powdered organic fertiliser
Raw material quality control
Selection of high-quality raw materials
It is important to pay attention to the source and quality of raw materials and to avoid the use of contaminated raw materials. For example, in the case of livestock and poultry manure, it is important to select manure from healthy livestock and poultry and avoid using manure from diseased livestock and poultry.
Testing the nutritional content of ingredients
The nutrient composition of raw materials is tested to understand the content of organic matter, nitrogen, phosphorus, potassium and other nutrients in the raw materials, so as to rationally adjust the formula. Chemical analysis methods or instrumental testing methods can be used to test the nutrient content of raw materials.
Controlling the moisture content of raw materials
High moisture content of raw materials will affect the effect of fermentation and maturation, so it is necessary to control the moisture content of raw materials below 60%. The moisture content of raw materials can be reduced through dehydration and natural drying.
Quality control of the production process
Control of temperature and time of fermentation and putrefaction
The temperature and time of fermentation and maturation are key factors affecting the quality of organic fertiliser. During the fermentation and maturation process, the temperature of the heap needs to be controlled between 50 – 60°C and the time between 20 – 30 days to ensure the maturity and quality of the organic fertiliser. The temperature and time of fermentation can be controlled by installing temperature sensors and turning the heap regularly.
Control of particle size for crushing and screening
The particle size of crushing and screening is an important factor affecting the quality of powdered organic fertiliser. During the crushing and sieving process, the particle size of organic fertiliser needs to be controlled between 0.5 – 1 cm to ensure the uniformity and fluidity of the organic fertiliser. The particle size can be controlled by adjusting the parameters of the crusher and sifter.
Testing quality indicators of powdered organic fertilisers
The quality indicators of powdered organic fertiliser are tested, including organic matter content, nitrogen, phosphorus and potassium content, moisture content, acidity and alkalinity, and heavy metal content. The method of testing can adopt national standards or industry standards. Professional testing organisations can be commissioned to carry out testing to ensure that the product quality meets the requirements.
Finished product quality control
Packaging quality control
Check the packaged powdered organic fertiliser to ensure that the packaging is intact, with no leakage, no breakage and so on. At the same time, attention should be paid to the marking and instructions of the packaging to ensure that the user can use the organic fertiliser correctly. The method of sampling inspection can be used to control the quality of packaging.
Storage quality control
Conduct regular inspections of stored powdered organic fertiliser to ensure that the storage environment is dry, ventilated, cool and free from direct sunlight and rain. At the same time, attention should be paid to the storage time to avoid expiry and failure of organic fertilisers. A storage management system can be established to regularly inspect and maintain the stored organic fertiliser.
Powdered organic fertiliser production equipment
Raw material pre-treatment equipment
It is used to pulverise raw materials such as livestock and poultry manure, crop stalks, etc. to make the particle size smaller for subsequent fermentation and processing. There are many types of pulveriser, such as hammer pulveriser, toothed roller pulveriser and so on. According to different raw materials and production scale, you can choose the right type of crusher.
If the moisture content of the raw material is too high, it needs to be dried with a dryer. The dryer can use hot air drying to reduce the moisture in the raw material to a suitable range. Common dryers include drum dryers, airflow dryers and so on.
Raw materials such as livestock manure may have odours that need to be treated with deodorisation equipment. Deodorisation equipment can use biological deodorisation, chemical deodorisation and other methods to remove odours from raw materials. For example, biofilter deodorisation equipment decomposes odorous substances through the action of microorganisms.
Fermentation and putrefaction equipment
In the process of compost fermentation, the pile needs to be turned regularly to ensure the supply of oxygen and uniform temperature in the pile. Compost turning machine can achieve automatic turning and improve the working efficiency. There are different types such as crawler type turning machine and trough type turning machine, which can be selected according to the production scale and site conditions.
Fermentation tank
If tank fermentation is used, a fermentation tank needs to be constructed. Fermentation tanks are generally made of concrete or steel structures with a certain depth and width to facilitate the stacking and fermentation of raw materials. The fermenter is usually equipped with ventilation and stirring devices to ensure the smooth progress of the fermentation process.
Crushing and screening equipment
The organic fertiliser after fermentation and maturation needs to be crushed again to make its particle size finer and reach the requirement of powder. Compared with the raw material pretreatment stage of the crusher, this stage of the crusher requires higher crushing accuracy and efficiency.
It is used to screen the crushed organic fertiliser to remove the impurities and large particles in it, and get the uniform powdery organic fertiliser. Common screening machines are vibrating screen, tumbler screen, etc., according to the production demand to choose the appropriate screening equipment.
Packaging and storage equipment
Packaging of powdered organic fertiliser for storage, transport and sale. The packaging machine can achieve automatic packaging and improve packaging efficiency and precision. There are different types of packaging machine such as open pocket packaging machine, valve pocket packaging machine, etc., which can be selected according to the packaging specifications and requirements.
In the production process, raw materials, semi-finished products and finished products need to be conveyed between different equipments. Conveying equipment can be belt conveyor, screw conveyor, bucket elevator and so on, according to the production site and material characteristics to choose the appropriate conveying method.
Fertiliser storage equipment
The produced powdered organic fertiliser needs to be stored in a dry and ventilated place. Storage equipment such as silos and warehouses can be used for storage. The storage equipment should have good sealing and moisture-proof performance to ensure the quality of organic fertiliser.
As an environmentally friendly, economical and efficient fertiliser, powdered organic fertiliser has a wide range of application prospects. Through reasonable selection of raw materials, optimisation of the production process, use of appropriate equipment and strict quality control, high quality powdered organic fertiliser can be produced to provide a sustainable source of nutrients for agricultural production.
