What Is In-Vessel Composting?

Also called composting. Refers to the biochemical process that utilizes microorganisms widely existing in nature to controllably promote the conversion of degradable organic matter in solid waste into stable humus. [1] Composting is a process of producing organic fertilizers, which contains rich nutrients and long-term and stable fertilizer effects. At the same time, it is conducive to the formation of solid particle structure of the soil, and can increase the ability of the soil to retain water, heat, breath, and fertilizer In addition, mixed use with chemical fertilizers can make up for the shortcomings of single nutrients in fertilizers and long-term single use of chemical fertilizers to compact the soil and reduce water and fertilizer performance. Composting uses various organic wastes (such as crop straws, weeds, leaves, peat, organic household waste, kitchen waste, sludge, human and animal waste, lees, fungus bran, and other wastes) as the main raw materials. Composted organic fertilizer.
Composting generally refers to composting

Also called composting. Refers to the biochemical process that utilizes microorganisms widely existing in nature to controllably promote the conversion of degradable organic matter in solid waste into stable humus. [1] Composting is a process of producing organic fertilizers, which contains rich nutrients and long-term and stable fertilizer effects. At the same time, it is conducive to the formation of solid particle structure of the soil, and can increase the ability of the soil to retain water, heat, breath, and fertilizer. In addition, mixed use with chemical fertilizers can make up for the shortcomings of single nutrients in fertilizers and long-term single use of chemical fertilizers to compact the soil and reduce water and fertilizer performance. Composting uses various organic wastes (such as crop straws, weeds, leaves, peat, organic household waste, kitchen waste, sludge, human and animal waste, lees, fungus bran, and other wastes) as the main raw materials. Composted organic fertilizer.

Chinese name

compost

Foreign name

Composting; Manure mixture for fertilizing;

Attributes

Organic fertilizer

Contains

Contains rich nutrients

Maturity

Important indicators of composting

Introduction to composting

Composting is a biochemical process that utilizes microorganisms such as bacteria, actinomycetes, and fungi that are widely distributed in nature to controlly promote the conversion of biodegradable organic matter to stable humus under certain artificial conditions. Kind of fermentation process. Composting

During the process, organic carbon is metabolized by microorganisms, which reduces the carbon-to-nitrogen ratio. The heat generated can make the compost temperature reach above 70 ° C, which can kill germs, eggs and weed seeds. After being piled up, it is relatively soft and easy to spread; after composting, it has no odor and has the aroma of earth.

High temperature compost

Principle of composting aerobic composting

According to the degree of oxygen demand during the composting process, it can be divided into aerobic compost and anaerobic compost. Aerobic composting is carried out under aerobic conditions with the help of aerobic microorganisms. During the composting process, the soluble organic matter in organic waste is absorbed by the microorganisms through the cell walls and cell membranes of the microorganisms; solid and colloidal organic matter first attaches to the outside of the microorganisms, and then breaks down into the action of extracellular enzymes secreted by the microorganisms. Soluble substances penetrate into the cells. Microorganisms oxidize part of the absorbed organic substances into simple inorganic substances through their own life activities, redox and biosynthetic processes, and release the energy required for microbial growth and activities to convert another part of the organic substances into new cellular material. Microorganisms are allowed to grow and multiply, producing more organisms, while the remaining organic matter that has not been degraded is partially converted into humus. Finally, the organic waste is mineralized and humified. At the same time, the high temperature (60-70 ° C) generated during the stacking is used to kill the germs, eggs and weed seeds brought by the raw materials to achieve harmlessness. . Therefore, in order to obtain high-quality compost, in the process of composting, every effort to create good conditions for the life activities of microorganisms is the key to accelerating compost maturation and improving fertilizer efficiency.

Compost classification

Compost can be divided into two types: general compost and high-temperature compost. The former fermentation temperature is lower, and the latter fermentation temperature is higher in the early stage, and compaction measures are generally adopted in the later stage. High-temperature composting has certain effects on promoting the maturation of crop stalks, human and animal manure, weeds, garbage sludge, and the killing of germs, eggs, and weed seeds. Simple high-temperature compost can use semi-pit stacking method and ground stacking method

Heap. The former has a pit depth of about 1 m, while the latter requires no pits. Both need ventilation channels to facilitate the growth and reproduction of aerobic microorganisms. Both need to be covered with a layer of crop stalks, etc., then a layer of human and animal dung, and poured with some lime water (the alkaline soil area does not need lime water), and then cover with a layer of soil. Generally, fermentation is performed at 55 ° C for 5-7d, and high temperature 70 ° C for 3-5d. If the temperature of the compost rises suddenly, it should be replenished in time. When the temperature of the compost is lowered below 40 ° C, most of the organic matter in the high-temperature compost will form humus.

Composting raw material composition

(1) A mixture of urine and feces excreted by the human body

Human feces contain about 70% to 80% moisture, 20% organic matter (fibers, fats, proteins, and salts such as silicon, phosphorus, calcium, magnesium, potassium, sodium and chlorides), a small amount of fecal odor, fecal bile Quality and pigment. Human urine moisture and urea, table salt, uric acid, hippuric acid, phosphate, ammonium salt, trace elements and auxin. Human feces and urine are often mixed with germs and parasite eggs, and should be harmless before application to avoid polluting the environment. Human urinary urine carbon-nitrogen ratio (C / N) is low, and it is easy to decompose; it contains more nitrogen, and can be used as quick-acting nitrogen fertilizer after maturity. It can be used as base fertilizer or topdressing fertilizer. It should be applied in combination with phosphorus and potassium fertilizers. However, it should not be mixed with alkaline fertilizer (grass ash, lime); it should not be used too much each time; dry land should be diluted with water and re-soiled after application; paddy fields should be combined with ploughing and shallow water should be poured to prevent volatilization, loss, and crops becoming too long. Avoid chlorine crops, so as not to affect the quality.

(2) Fertilizer made by mixing and stacking livestock manure and washer materials and feed residues and acting on microorganisms

Rich in organic matter and various nutrients. Among all kinds of animal manure, sheep manure has high nitrogen, phosphorus, and potassium content, followed by pig and horse manure, and cow manure is the lowest; excretion amount is the most, followed by pig and horse, and the sheep manure is the least. Gasket materials include straw, weeds, fallen leaves, peat and dry soil. The manure is divided into the inner ring system (the washer material is directly sprinkled into the pen to absorb feces and urine) and the outer ring system (the livestock manure is cleared out of the pen and the washer material is stacked one by one). Decomposes after being decomposed. During the production process, its chemical composition changes due to the action of microorganisms. The role of manure: Provide plant nutrients. Includes essential nutrients such as nitrogen, phosphorus, potassium, calcium, magnesium, sulfur and trace elements iron, manganese, boron, zinc, molybdenum, copper and other inorganic nutrients; amino acids, amides, nucleic acids and other organic nutrients and active substances such as vitamins B1, B6 Wait. Maintain a relative balance of nutrients. Improve the effectiveness of soil nutrients. The manure contains a large number of microorganisms and various enzymes (protease, urease, phosphorylase), which promotes the organic nitrogen and phosphorus to become inorganic for the crops to absorb. And can make calcium, magnesium, iron, aluminum and other stable complexes in the soil, reduce the fixation of phosphorus, and increase the effective phosphorus content. Improve the soil structure. Humus colloids promote the formation of soil aggregate structure, reduce bulk density, improve soil permeability, and coordinate water and air contradictions. It can also improve soil buffering and improve mine poisoning fields. Fertilize soil fertility to improve soil fertility and water retention. The manure is mainly used as a base fertilizer after decomposing. The nutrients of fresh manure are mostly organic, and the carbon / nitrogen ratio (C / N) value is large, so it should not be applied directly, especially not directly into the rice field.

(3) Plant stalks, green manure, weeds, and other plant materials are mixed with soil, human waste, garbage, etc.

Most of the piled fertilizers are used as base fertilizers, and large application rates can provide nutrients and improve soil properties, especially for improving sand, clay and saline soil.

(4) Fertilizers of crop stalks, green manure, weeds, and other plant matter, which are placed in ponds with river, pond mud, and human feces, and are anaerobic fermented by microorganisms.

Generally used as basal fertilizer into rice fields. Manure can be divided into two types: manure and grass pond mud. Manure can be accumulated at any time, and grass pond mud is accumulated in winter and spring. Due to the lack of oxygen during the accumulation, a large amount of intermediates of divalent iron, manganese and various organic acids are accumulated, and the excessively high carbon-nitrogen ratio and insufficient calcium and magnesium nutrients are not conducive to microbial activity. Ponds should be turned and added with green manure and appropriate amount of human urine, lime, etc. to supplement oxygen, reduce the ratio of carbon and nitrogen, improve the nutritional status of microorganisms, and accelerate maturation.

Biogas fertilizer: crop straw, grass, human waste and other residues after biogas fermentation in a biogas tank. Rich in organics and essential nutrients. Biogas fermentation is slow, organic matter is consumed less, nitrogen, phosphorus, and potassium losses are small. Nitrogen recovery is 95% and potassium is above 90%.

Biogas slurry can be used as topdressing fertilizer on dry land; biogas residue is used as paddy field fertilizer, and soil should be reconstituted if applied as dry land base fertilizer. Biogas fertilizer should be stacked for several days after it is used out of the pond.

In addition, the composting process is closely combined with other methods for comprehensive utilization of compost products. For example, the combination of earthworm breeding and composting, the use of organic waste to raise earthworms, and the use of earthworms to make compound feeds, and the use of earthworm dung as a high-quality fertilizer for the cultivation of pollution-free vegetables.

Composting process

Compost material

The materials used to make compost can be roughly divided into three categories according to their properties:

The first category: basic materials that are not easily decomposed, such as various crop straws, weeds, fallen leaves, vines, peat, garbage, vegetable waste, etc.

The second category: substances that promote decomposition are generally substances that contain more nitrogen and are rich in high-temperature fiber-decomposing bacteria, such as human and livestock urine, sewage, silkworm sand, horse dung, sheep dung, old compost, plant ash, and lime.

The third type: adding a small amount of peat, fine soil and a small amount of superphosphate or phosphate rock during the accumulation process can prevent and reduce the volatilization of ammonia and improve the fertilizer efficiency of compost.

Material handling

To accelerate decay, different materials are processed before being stacked.

(1) Municipal garbage should be sorted. Broken glass, stones, tiles, plastics and other debris should be selected. Especially, heavy metals and toxic organic and inorganic substances should be prevented from entering.

(2) In principle, it is better to crush all kinds of stacked materials. Increasing the contact area is good for decay, but it requires more energy and manpower and is difficult to promote. Generally, it is better to cut various stacked materials into 2-5 inches long.

(3) For hard and waxy materials, such as corn and sorghum rods, the water absorption is low. It is best to soak the material powder with sewage or 2% lime water to destroy the waxy layer on the surface of the straw and use water absorption. Promote decay.

(4) Aquatic weeds, due to excessive water content, should be allowed to dry slightly before being stacked.

Composting site

The stacking site should be selected where the terrain is high, the leeward is sunny, the water is near, and the transportation is convenient. For transportation convenience, the stacking sites can be appropriately dispersed. After selecting the stacking site, level the ground.

Ventilation holes for composting

On the leveled and compacted site, excavate T -shaped or Well -shaped trenches, each about 15-20 cm deep and wide. The trenches are covered with hard and strong crop straws vertically and horizontally to serve as ventilation trenches at the bottom of the compost. At the intersection of two small trenches, wooden sticks or long thick straws bundled in bundles are placed perpendicular to the ground to serve as a vent hole for composting.

Formulation ratio of composting composting materials

The general proportion of stacked materials is: about 1000 kg of various crop straws, weeds, fallen leaves, etc., adding 200-300 kg of feces and 100-200 kg of water (the amount of water depends on the wet and dry of the raw materials), each layer can Appropriately cover a thin layer of soil, mainly to play the role of limestone, peat and so on. In order to accelerate the maturation, each layer can be inoculated with high-moisture decomposing fiber bacteria (such as enzyme bacteria). If it is lacking, you can add an appropriate amount of horse dung or old compost, deep underground ditch mud and fertile soil to promote decomposition. But the soil should not be too much, so as not to affect the quality of compost and compost. So the farm proverb says: grass is not rotten without mud, mud is not fat without grass. This fully shows that adding the right amount of fertilizer not only has the effect of absorbing and retaining fertilizer, but also has the effect of promoting the decomposition of organic matter. ^[1]

Compost

A layer of sludge, fine soil or turf soil with a thickness of about 20 cm is laid on the ventilation ditch of the dumping site as a bottom pad for absorbing infiltration fertilizer. Then the processed materials (after being thoroughly mixed) are stacked layer by layer and solid. Spread manure, urine, and water on each layer, and then evenly sprinkle a small amount of lime, phosphate rock powder or other phosphate fertilizers (the pile materials have not been treated with lime water), as well as sheep and horse feces, old compost or inoculation High-temperature fibers break down bacteria. Each floor needs to be "full, drink enough, and tightly closed." The so-called "satisfaction" means that the straw and urea or soil fertilizer and wheat bran to adjust the carbon-nitrogen ratio should be added to the required amount to ensure the quality of compost. "Drinking enough" means that the straw must be saturated with water. Adding enough water is the key to composting. "Strictly closed" means that after the pile is sealed with soil, it can play the role of heat preservation and water retention. Stacked layer by layer until it reaches 4-6 feet (between 1.2 meters / 1.5 meters). The thickness of each layer is usually 1-2 (15 / 25cm) feet. The upper layer should be thin, and the middle and lower layers are slightly thicker. The amount of manure, urine, and water added to each layer should be more in the upper layer and less in the lower layer. Below, it is evenly distributed from top to bottom. The pile width and length depend on the amount of material taken and the convenience of operation. The pile shape can be made into a bun shape or other shapes. After being piled up, it should be sealed with 2-inch thick mud, fine soil and old plastic film in time, which is beneficial to heat preservation, water retention and fertilizer retention. A circular groove is then opened around to facilitate drainage. ^[2]

Post- compost management

Generally, 3-5 days after the heap, the organic matter begins to be decomposed by the microorganisms to release heat, and the temperature in the heap slowly rises. After 7-8 days, the temperature in the heap rises significantly to 60-70 ° C. The high temperature easily causes the lack of moisture in the heap, which makes the microorganism The activity is weakened, and the decomposition of raw materials is incomplete. Therefore, during the stacking process, the moisture and temperature changes in the upper, middle and lower parts of the stack must be checked frequently. Inspection methods can be tested with a compost thermometer. If you don't have a compost thermometer, you can insert a long iron rod into the heap, leave it for 5 minutes, and pull it out and try it by hand. The temperature of the hand is about 30 ° C, the temperature is about 40-50 ° C, and the temperature is about 60 ° C. Check the moisture to observe the wet and dry condition of the surface where the iron rod is inserted. If it is in a wet state, it means an appropriate amount of water; if it is in a dry state, it means that there is too little water. If the moisture and ventilation in the reactor are adapted, the temperature will gradually increase in the first few days after the reactor, and the highest temperature can be reached in one week. The high temperature stage should be maintained for no less than 3 days, and the temperature will slowly decrease after 10 days. Under this normal situation, the pile is turned once in 20-25 days, the outer layer is turned to the middle, the middle is turned to the outside, and an appropriate amount of feces and urine is added to re-accumulate as needed to promote rot. After re-stacking, in another 20-30 days, the raw materials are nearly black, rotten, and odorous, indicating that they are basically rotten. You can use it, or compact the cover soil and save it for future use. ^[3]

Good conditions for composting

(1) Moisture. Maintaining proper water content is the first condition for promoting microbial activity and compost fermentation. Generally, 60% to 75% of the maximum water holding capacity of the compost material is appropriate.

(2) Ventilation. Maintaining proper air in the reactor is conducive to the reproduction and activity of aerobic microorganisms, and promotes the decomposition of organic matter. When composting at high temperature, we should pay attention to the moderate tightness of the pile to facilitate ventilation.

(3) Maintain a neutral or slightly alkaline environment. Appropriate amount of lime or calcareous soil can be added to neutralize and adjust acidity to promote microbial reproduction and activity.

(4) Carbon-nitrogen ratio. The carbon-to-nitrogen ratio of microorganisms to the normal decomposition of organic matter is 25: 1. The leguminous green manure has a carbon-nitrogen ratio of 15-25: 1, weeds of 25-45: 1, and gramineous crop stalks of 60-100: 1. Therefore, according to the type of compost material, an appropriate amount of a higher nitrogen-containing substance is added to reduce the carbon-nitrogen ratio and promote microbial activity ^[4] .

Inspection standards for composting and maturity

Compost maturity is a comprehensive indicator to identify compost quality. It can be judged according to its color, odor, straw hardness, compost leachate, compost volume, carbon-nitrogen ratio and humus coefficient.

(1) From the perspective of color and odor, the stalks of rotten compost turned brown or dark brown with black juice and ammonia smell. The ammonium nitrogen content was significantly increased by the rapid measurement with ammonium reagent.

(2) Straw hardness, holding compost with hands, soft and elastic when warm; brittle when dry, easily broken, organic matter loses elasticity.

(3) Compost leaching solution, take rotten compost, stir with fresh water (fertilizer-water ratio 1: 5-10), leave it for 3-5 minutes, and its leaching solution is pale yellow.

(4) The compost volume is reduced by 2 / 3-1 / 2 compared with the time of composting.

(5) Carbonitriding, generally 20-30: 1 (25: 1 is best)

(6) Humicification coefficient is about 30%.

Compost that meets the above-mentioned indicators is a high-quality compost with good fertilizer efficiency, and can be applied to various soils and crops. Adhere to long-term application, not only can obtain high yield, but also have significant effects on improving soil and improving soil fertility.