10 Question 10 Answer the most headache problem of livestock and poultry manure disposal!

1. What is manure?

As the name suggests, manure refers to the waste such as manure and sewage produced in the process of livestock and poultry breeding. Broadly speaking, manure includes manure, urine, bedding, rinsing water, animal carcasses, feed residues and odors generated in the process of livestock and poultry breeding; In a narrow sense, manure refers to livestock and poultry manure, urine excrement and its mixture with rinsing water. In this paper, the treatment and utilization of feces and their flushing water mixtures are mainly introduced.

2. What are the main forms of manure?

The morphology of manure is distinguished according to the solid and moisture content in it: intuitively, manure mainly exists in two different forms: solid and liquid; If the solid content in the manure can be further subdivided into solid, semi-solid, slurry and liquid, the solid content of these four forms is >20%, 10%~20%, 5%~10% and <5% respectively. Due to the different types of livestock and poultry, the physiological and metabolic processes are different, the degree of dryness and wetness of the excreted feces and the amount of urine are also different, so the state of the excretion is also different (as shown in the figure below). There is not always a clear dividing line between adjacent forms of manure, such as slurry and semi-solids.

When the manure is affected by the external environment, the solid content or moisture content in it changes, it may change from one form to another, and factors such as animal breed, feeding diet, type and quantity of bedding may affect the form of manure.

3. What factors affect the excretion of livestock and poultry manure and urine?

Different livestock and poultry due to individual differences, their fecal volume is very different, such as adult cattle daily fecal volume of 20 kg ~ 35 kg, while the daily fecal volume of laying hens is only 0.14 kg ~ 0.16 kg. Even for the same type of animal, the amount of manure excreted by animals will vary depending on their sex, age, weight, growth stage and the nature of the diet they are fed. The results showed that the amount of fecal excretion of sheep was significantly positively correlated with feed intake and body weight, and the fecal amount of the same breed of ram was greater than that of ewes.

The amount of urine excreted by livestock and poultry is affected by factors such as breed, age, type of production, feed, service status, season and outside temperature, and any change in factors will change the amount of urine produced by animals. Poultry urine volume is less, adult chickens urine volume 60 ml ~ 180 ml day and night, because poultry urine is mixed with feces in the cloaca and excreted, generally not measured separately. In the case of the same individual, the amount of urine in the animal depends mainly on the amount of water ingested and the amount of water excreted by other means, and when the protein or salt content of the diet is high, the amount of water consumed increases and the amount of urine increases; When the outside temperature is high and the amount of activity is high, the amount of water excreted by the lungs or skin increases, resulting in a decrease in urine output; Certain pathologic causes often cause significant changes in urine output.

4. What are the main sources of aquaculture sewage?

Farm sewage mainly comes from livestock and poultry house flushing water, dripping drinking water, cooling water and farm domestic sewage. The amount of water used for flushing depends on the manure removal process, and the amount of water used for flushing varies greatly from different manure removal processes, so the amount of aquaculture wastewater also varies greatly. For pig farms, if the fermentation bed pig production process is adopted, the amount of water used in the production process is very little or even not flushed, so the amount of breeding sewage is little or even none; However, if the water flushing process is adopted, the manure excreted by livestock and poultry is all collected by water flushing, and the amount of water used for flushing is large, and the amount of sewage is also very large. The drip drinking water mainly comes from the joint of the drinking water or drinking water system, if the drinking water is not closed tightly or the joint of the drinking water system is damaged or loose because of the quality problem, there will be water continuous dripping, in addition the installation height of the drinking water is not suitable, and the dripping phenomenon will also occur in the process of animal drinking water, and the drinking water of these drips will also be mixed with manure.

5. Why is cleaning important?

In modern livestock and poultry farms, especially large-scale farms, livestock and poultry are raised in livestock and poultry houses, their production, reproduction and other life activities are completed in livestock and poultry houses, and the feces and urine generated by their life metabolism are also excreted to livestock and poultry houses. If the feces and urine excreted by livestock and poultry are not cleaned out in time, the feces and urine waste will be degraded to a certain extent under the action of microorganisms. Volatilized ammonia, hydrogen sulfide and other harmful gases, these harmful gases accumulate in the livestock house, resulting in a decline in the quality of the air environment in the livestock house, livestock will feel uncomfortable, their growth and reproductive performance will be affected, and may even cause disease and death in serious cases.

Not only that, livestock feces and urine also contain a variety of microorganisms, including pathogenic microorganisms, if the feces and urine with pathogenic microorganisms remain in the livestock and poultry house for a long time, it may also appear the spread of pathogenic microorganisms. It can be seen that manure removal is an important link in the livestock and poultry breeding process, which not only helps to keep the environment in the livestock and poultry house clean, but also helps to reduce the occurrence of diseases. Therefore, in the process of livestock and poultry breeding, appropriate ways should be taken to clean up the feces in the livestock and poultry house in time, so as to facilitate harmless treatment in the later stage.

6. How to choose the feces cleaning method?

At present, the main methods of feces removal in livestock and poultry breeding include dry feces removal, water flushing feces removal and blister feces removal. The selection of feces removal methods should follow the following principles:

First of all, the method of manure removal should be cross-referenced with the post-treatment process of manure. Manure removal is only a link in the process of manure management, it must be connected with other links in the process of manure management to form a complete management system, in order to achieve effective management of manure. That is to say, the subsequent waste treatment technology can be determined according to the selected waste removal method; It is also possible to determine the matching method of cleaning feces according to the selected feces treatment technology. For example, if a pig farm intends to use biogas engineering to treat the manure, the best way to remove the manure in the pig farm is to choose the blister manure. Similarly, if a pig farm adopts the method of blister manure removal, it is not appropriate to determine the post-treatment of the manure as the standard discharge treatment, because the concentration of organic matter in the feces of the blister feces is very high, and the purification treatment of such feces obviously has to pay a high price and is not worth the loss.

Secondly, the selection of manure removal methods should also consider the types of livestock and poultry, feeding methods, labor costs, farm economic conditions and other factors. Due to the different types of livestock and poultry, their biological habits and production processes are different, and the choice of fecal cleaning method also has an impact, for example, laying hens are mainly raised in laminated cages, because the chicken urine in the cloacal and feces mixed out of the body, the production process almost only produces solid feces, so the dry fecal cleaning method.

7. What is dry cleaning?

Dry manure cleaning is a method of collecting all or most of the solid feces from the ground of the livestock and poultry house manually or mechanically, and washing the residual feces on the ground with a small amount of water to separate the solid and liquid waste.

The main objective of the dry cleaning process is to prevent the mixing of solid faeces with urine and sewage as far as possible by diverting the faeces as soon as they are produced, collecting, cleaning and carrying away the dry faeces mechanically or manually, and disposing of the urine and flushing water separately from the sewers.

The advantages of dry cleaning include: less water for flushing and less water consumption; The low content of organic matter in sewage is conducive to simplifying the process and equipment of sewage post-treatment and reducing the cost of sewage post-treatment. Maintain the nutrients of solid manure, improve the efficiency of organic fertilizer, and facilitate the utilization of manure resources; It can effectively remove the feces and urine in the livestock and poultry house and maintain the environmental health of the livestock and poultry house.

The dry cleaning process is divided into two kinds: manual cleaning and mechanical cleaning.

8. What is manual defecation?

Manual manure removal is one of the dry manure removal methods, which can be completed by manually cleaning the solid feces on the ground of the livestock and poultry house. Most of the solid feces in the livestock and poultry houses are manually cleaned and sent to the manure storage facilities by wheelbarrow for temporary storage; The residual feces and urine on the ground are washed with a small amount of water, and the sewage is discharged into the manure storage tank outside the house through the feces ditch. The advantages of this method are no electricity, less one-time investment, and separation of feces and urine. The disadvantage is the large amount of labor and low production efficiency.

9. What is mechanical manure removal?

Mechanical manure removal is also one of the dry manure removal methods, which uses special mechanical equipment instead of manual cleaning of solid feces on the floor of the livestock and poultry house, and the mechanical equipment directly transport the collected solid feces to the outside of the livestock and poultry house, or directly transport to the manure storage facilities; The residual feces and urine on the ground are also washed with a small amount of water, and the sewage is discharged into the manure storage tank outside the house through the feces ditch.

The advantages of mechanical manure cleaning are fast and convenient, saving labor force and improving work efficiency; Compared with manual stool cleaning, it will not cause stool pollution in the hallway of the house. The disadvantage is that the one-time investment is large, but also spend a certain amount of operation and maintenance costs; The working parts are covered with feces, and maintenance is difficult; The noise of the cleaning machine is large, which is not conducive to the growth of livestock and poultry. In addition, the domestic production of feces cleaning equipment in the use of reliability is still some lack of high incidence of failure. Although there are still some problems in the current use of manure removal equipment, with the progress of livestock mechanical engineering technology, the performance of manure removal equipment will continue to improve, and mechanical manure removal is also an inevitable trend in the development of modern large-scale farming.

10. What is the role of solid-liquid separation?

Solid-liquid separation is a pre-treatment process of manure, through the use of physical or chemical methods and equipment to separate the solid matter in feces from the liquid. This method can separate the suspended solids, long fibers, weeds and so on in the manure, and usually can reduce the chemical oxygen demand in the manure by 14% to 16%.

After the separation of solid and liquid, the solid part is easy to transport, dry, make organic fertilizer or use as cow mattress material. The liquid part is not only easy to transport and store, but also convenient for subsequent treatment due to the low organic content of the liquid part. At present, the main methods of solid-liquid separation are chemical sedimentation, mechanical screening, spiral extrusion, decanter centrifugal dehydration and so on.