JP7560396B2 - Bedding for pets - Google Patents

Description

The present invention relates to bedding for captive animals.

For livestock, pets, zoo animals, and other animals kept in captivity, bedding such as rice straw, wheat straw, and sawdust is laid on the floors of the facilities to improve the environment. The bedding has the functions of absorbing feces and urine, and of providing cushioning and anti-slip properties to protect the legs of the animals. However, if the amount of feces and urine absorbed exceeds the limit, not only will the odor from the feces and urine increase the risk of stress and illness, but it will also worsen the working environment, making it impossible to maintain a safe environment for the animals. In addition, environmentally friendly disposal is being promoted, such as reuse through composting after use, but there is a limit to the amount that can be disposed of. Furthermore, sawdust is becoming more difficult to obtain because the amount produced is decreasing due to various factors such as the expansion of demand for biomass fuel, the decline of domestic forestry and lumber industries, the increase in lumber imports, the sluggish rate of housing starts, and the decrease in the proportion of wooden buildings.

In light of this, the water-absorbing properties of paper sludge have been focused on, and its application as a bedding material has been considered. For example, a material for treating animal waste has been proposed in which a mixed pulp produced by mixing pulp and paper sludge is used as a base material, which is then granulated and dried (Patent Document 1). In addition, a water-absorbing treatment material has also been proposed that comprises granulated material whose main material is paper sludge that has been pulverized when its moisture content is 40% by weight or more (Patent Document 2).

Japanese Patent Application Publication No. 7-313010 JP 2016-41039 A

Paper sludge contains cellulose, a biomass component, and when it absorbs water and becomes wet, its pH becomes around 8, making it easy for bacteria such as E. coli to grow. As a result, the following problems arise. For example, dairy cows spend most of their time lying down in breeding facilities, with their udders in contact with the ground for long periods of time. If E. coli or other bacteria enter the udders during this contact, they will develop mastitis, resulting in a decrease in milk volume and quality (contamination with foreign bacteria). Antibiotics are taken to cure mastitis, but after administration, raw milk cannot be shipped until antibiotics are no longer detectable in the milk, resulting in a decrease in raw milk production.
An object of the present invention is to provide a bedding material for farm animals in which bacterial growth is inhibited despite the inclusion of papermaking sludge.

As a result of research conducted in light of the above problems, the inventors have discovered that by adding crushed lightweight cellular concrete to paper sludge so that the pH, measured by a specified method, falls within a specific range, it is possible to obtain bedding for captive animals in which bacterial growth is suppressed, despite the inclusion of paper sludge.

That is, the present invention provides the following [1] to [6].
[1] Papermaking sludge;
and crushed lightweight cellular concrete.
The litter for farmed animals has a pH of 9 to 11 when a suspension containing 2.5 times the mass of the litter for farmed animals and distilled water is added thereto.
[2] The bedding material for pet animals according to the above [1], wherein the crushed lightweight cellular concrete has a particle diameter _D10 of 1 mm or more and a particle diameter _D90 of 4 mm or less.
[3] The bedding material for farmed animals according to [1] or [2] above, further comprising biomass ash.
[4] Papermaking sludge;
A method for producing bedding for captive animals includes a step of preparing a mixture containing crushed lightweight cellular concrete, the mixture having a pH of 9 to 11 when suspended in distilled water in an amount 2.5 times the mass of the mixture.
[5] Papermaking sludge;
and crushed lightweight cellular concrete, wherein the pH of a suspension obtained by adding 2.5 times the mass of distilled water to the mixture is 9 to 11.
A method for inhibiting bacterial growth in animal bedding containing paper sludge.
[6] The method for inhibiting according to [5] above, wherein the bacteria is one or more bacteria selected from gram-positive bacteria and gram-negative bacteria.

The present invention provides bedding for captive animals that inhibits bacterial growth despite containing paper sludge.

The bedding material for farm animals of the present invention will be described in detail below.
The litter for farm animals of the present invention contains papermaking sludge. Here, in this specification, "papermaking sludge" refers to wastewater treatment sludge (dehydrated sludge) from a papermaking factory, and includes sludge generated from a pulp manufacturing process, a paper manufacturing process, a wastepaper processing process, etc. Specific examples of the sludge include mixed sludge obtained by mixing all wastewater treatment sludge generated in a factory, sludge mainly composed of fibrous material recovered from pulp-related wastewater in a pressurized flotation device, a simple sedimentation tank, a coagulation sedimentation tank, a fiber recovery device, etc. (DIP sludge), and excess sludge generated in an activated sludge device.

The papermaking sludge may be dry papermaking sludge with low moisture content or wet papermaking sludge with high moisture content, but dry papermaking sludge is preferred from the viewpoint of the pH adjustment effect and reduced thermal conductivity by lightweight aerated concrete (hereinafter also referred to as "ALC") described later. Here, "dry papermaking sludge" in this specification refers to papermaking sludge with a moisture content of less than 20% by mass, and papermaking sludge with a moisture content of more than 20% by mass is referred to as "wet papermaking sludge." In this specification, the "moisture content" is calculated from the mass loss when 100 g of papermaking sludge is dried at 105°C for 24 hours.
The paper sludge may be one type or two or more types, and dry paper sludge and wet paper sludge may be combined.

The bedding for farm animals of the present invention also contains crushed ALC. By including crushed ALC, which is an alkaline porous inorganic material, in the bedding for farm animals, not only can the pH of the bedding for farm animals be made weakly alkaline, making it difficult for bacteria to grow, but it can also provide appropriate breathability and insulation (heat retention) effects.

The crushed ALC is obtained by crushing ALC obtained by autoclaving silica stone, cement, quicklime, aluminum powder, etc. (for example, curing for 10 hours in high-pressure steam at 180° C. and 1 MPa).
Waste ALC may be used as the ALC. Examples of waste ALC include used ALC and scraps and defective products generated during the production and processing of ALC in factories, etc.
One or more types of ALC may be contained, and ALC and waste ALC may be combined.

The crushed ALC material can be obtained, for example, by crushing the ALC with a crusher. Examples of the crusher include a jaw crusher, an impact crusher, a hammer crusher, a roll crusher, and a rotary crusher. The crusher may be equipped with a screen with a desired mesh size for the purpose of adjusting the particle size.

If the particle size of the crushed ALC is too fine, it may generate smoke (dust) or become lumpy when mixed with paper sludge, and if the particle size is too coarse, it may get stuck between the hooves. Therefore, in the present invention, crushed ALC having a particle size distribution of 1 mm or more and a particle size D ₉₀ of 4 _mm or less is preferably used. From the viewpoint of suppressing smoke generation and lumps during mixing, the particle size D ₁₀ is preferably 1.2 mm or more, and more preferably 1.5 mm or more. Also, from the viewpoint of preventing damage to the hooves, the particle size D ₉₀ is preferably 3.9 mm or less, and more preferably 3.8 mm or less. Here, in this specification, "particle size distribution" refers to a volume-based particle size distribution measured based on a sieving method using a sieve specified in JIS Z 8801-1:2019 "Test sieves - Part 1: Metal mesh sieves" and JIS R 1629 "Method for measuring particle size distribution by laser diffraction and scattering method for fine ceramic raw materials". The particle size distribution is represented by a distribution curve with the horizontal axis representing particle size (μm) and the vertical axis representing the volume-based frequency (%). As a laser diffraction and scattering method particle size measuring device, for example, Microtrack (manufactured by Nikkiso Co., Ltd.) can be used. In addition, in this specification, "particle size D ₁₀ " refers to the cumulative 10% particle size in the volume-based particle size distribution, and "particle size D ₉₀ " refers to the cumulative 90% particle size in the volume-based particle size distribution. In order to collect crushed material having the above particle size distribution, a sieve separator such as a vibrating sieve or a rotary sieve can be used, and it is sufficient to install a desired sieve size.

The pH of the litter for farmed animals of the present invention, when measured by a predetermined method, falls within the range of 9 to 11. This makes it possible to inhibit bacterial proliferation in the litter for farmed animals.
The bacteria is preferably one or more bacteria selected from gram-positive bacteria and gram-negative bacteria. Examples of gram-positive bacteria include Staphylococcus aureus, Bacillus subtilis, and Streptococcus. Examples of gram-negative bacteria include Pseudomonas aeruginosa, Escherichia coli, Legionella, Salmonella, and Shigella. In particular, it is effective against Escherichia coli and Staphylococcus aureus. For example, it is known that mastitis in dairy cows is caused by Escherichia coli and Staphylococcus aureus, and the optimal pH for Escherichia coli is 7 to 8, and the optimal pH for Staphylococcus aureus is 6.5 to 8. On the other hand, paper sludge contains cellulose, which is a biomass component, and has a pH of about 8 in a wet state, so that when paper sludge is used as a bedding material for livestock, bacteria such as Escherichia coli and Staphylococcus aureus are likely to grow. Therefore, in the present invention, the lower limit of the pH of the bedding material for captive animals is set to 9 or higher, at which bacteria such as Escherichia coli and Staphylococcus aureus are unlikely to grow, and the upper limit of the pH is set to 11 or lower, at which the captive animals are unlikely to suffer from alkali burns (skin tanning).

The pH of the litter for farmed animals of the present invention is preferably 9.1 to 10.8, more preferably 9.2 to 10.5, from the viewpoint of further suppressing bacterial proliferation and alkali burn.
The pH of the litter for farm animals is measured using a pH meter for a suspension obtained by adding 2.5 times the mass of the litter for farm animals to distilled water, in accordance with "2-1 Soil pH" under "I Soil Analysis Method" in the "Ibaraki Prefecture Soil and Crop Nutrition Diagnostic Manual" published by the Ministry of Agriculture, Forestry and Fisheries. For example, a Standard Tou pH Electrode Set (manufactured by HORIBA) can be used as the pH meter. Specifically, the procedure is as follows:

[pH Measurement]
Distilled water is added in an amount 2.5 times by mass of the animal litter, and the mixture is shaken for 30 minutes. A glass electrode is immersed in the resulting suspension, and the pH is measured after 30 seconds.

The suspension is shaken at any speed that allows the animal litter to be sufficiently mixed with the distilled water, for example, at 100 rpm. The measurement temperature is usually room temperature, for example, 23°C.

The thermal conductivity of the bedding for farm animals of the present invention is preferably 0.3 W/m·K or less, and more preferably 0.15 to 0.25 W/m·K, from the viewpoint of preventing a decrease in milk yield due to the coldness of the udders of dairy cows. The thermal conductivity of the bedding for farm animals is measured in accordance with JIS A 1412-2:1999 "Method of measurement of thermal resistance and thermal conductivity of thermal insulating materials - Part 2: Heat flow meter method (HFM method)".

The contents of paper sludge and crushed ALC in the animal litter of the present invention can be appropriately selected so that the pH of the animal litter falls within the above range, for example, as follows.
When wet papermaking sludge is contained as the papermaking sludge, the content of crushed ALC material in the pet animal litter of the present invention is usually 45 mass%, preferably 50 to 99 mass%, more preferably 53 to 97 mass%, and even more preferably 55 to 95 mass%, based on the total amount of the papermaking sludge and the crushed ALC material being 100 mass%.
When dried papermaking sludge is contained as the papermaking sludge, the content of crushed ALC material in the pet animal litter of the present invention is usually 15 mass%, preferably 18 to 99 mass%, more preferably 20 to 97 mass%, and even more preferably 20 to 95 mass%, based on the total amount of the papermaking sludge and the crushed ALC material being 100 mass%.
By setting the content in this range, it is possible to sufficiently suppress the proliferation of bacteria while maintaining sufficient heat insulating performance and water absorbing performance.

In the present invention, a pH adjuster may be contained in order to adjust the pH of the litter for farm animals to fall within the above range.
Examples of pH adjusters include slaked lime, quicklime, magnesium hydroxide, paper sludge incineration ash (PS ash), coal ash, and volcanic ash. Among them, slaked lime and quicklime have a high pH, so they can reduce the content of crushed ALC and are useful as pH adjusters for keeping the pH of the pet litter below pH 9 within the above range. The content of the pH adjuster can be appropriately set according to the type so as to achieve the desired pH while maintaining the desired paper sludge content.

Furthermore, the animal litter of the present invention may contain biomass ash. This not only suppresses the formation of lumps that tend to occur when using paper sludge with a high moisture content, but also has the effect of adjusting the pH. In addition, since it contains a large amount of calcium and potassium, it is possible to produce compost from the used animal litter, thereby adding value.
Here, in this specification, "biomass ash" refers to the incineration ash of biomass, and is a concept that includes, for example, the incineration ash of plants and bamboo, the incineration ash of food waste, and the incineration ash of biomass and coal mixed in a biomass power plant, etc. It may be fly ash or bottom ash obtained by collecting soot dust suspended as a gas in the combustion exhaust gas in a dry state using a dust collector. Among them, the combustion ash of plants and bamboo is preferred because it has a relatively high K ₂ O content and can be used as a useful compost. The K ₂ O content is preferably 2% by mass or more, more preferably 3% by mass or more, and even more preferably 3% by mass or more. In addition, the incineration ash of biomass and coal mixed is preferably one having a biomass ratio of 50% by mass or more.
Generally, combustion furnaces for biomass power generation are of the stoker type and the fluidized bed type, and in the case of the circulating fluidized bed type and the pressurized fluidized bed type, limestone is added to the combustion furnace for desulfurization. Biomass ash from such combustion furnaces contains a large amount of calcium components, and the CaO content is generally 5 to 45 mass %. In addition, calcium compounds derived from the added limestone include quicklime, slaked lime, calcium carbonate, and the like. Fly ash of biomass ash contains more of these calcium compounds than bottom ash. Therefore, fly ash discharged from a fluidized bed type combustion furnace is preferable as biomass ash from the viewpoint of suppressing the generation of lumps and adjusting the pH.

The amount of biomass ash used is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more, based on the total amount of paper sludge and crushed ALC material being 100% by mass, from the viewpoints of suppressing lumps and increasing the concentration of calcium and potassium, and is preferably 10.0% by mass or less, more preferably 9.0% by mass or less, and even more preferably 8.0% by mass or less, from the viewpoint of suppressing alkali burning.

Furthermore, the bedding material for farm animals of the present invention may contain paper sludge incineration ash. Here, in this specification, "paper sludge incineration ash" refers to the incineration ash of the paper sludge described above. This not only makes it possible to suppress the formation of lumps that tend to occur when using paper sludge with a high moisture content, but also has the potential to adjust the pH. In addition, because the paper sludge and the paper sludge incineration ash are discharged from the same source, they are easy to mix and transport, and have the advantage that they can be dried using the residual heat of the incineration equipment or the incineration ash immediately after collection.

The bedding material for farmed animals of the present invention is used exclusively as bedding material for treating feces and urine of farmed animals such as dairy cows, cows, pigs, laying hens, broilers, and other livestock, as well as pets and zoo animals, and for maintaining the farming environment, and is particularly effective when used for dairy cows.
The animal litter of the present invention may be spread over the entire area or a part of the area where animals are kept. For example, in the case of tethered cattle, it may be spread only around the hooves or milk.
The time of application is not particularly limited, but it is more effective to apply after removing feces or cleaning. If the amount of bedding for pets decreases, new bedding for pets may be added as necessary.

Used animal litter containing manure and feces is easy to filter because it contains crushed ALC, and solid-liquid separation is possible using a filter press or the like.
The ALC contained in the bedding material for farm animals of the present invention has a high phosphorus absorption coefficient, so phosphorus in the feces and urine is adsorbed. Therefore, the collected liquid portion can be disposed of without the need for new wastewater treatment, since the phosphorus concentration, which is a substance that causes water pollution, is reduced by the ALC. The collected solid portion can be disposed of like normal bedding materials, but can be used as compost due to the characteristics of the ALC, such as water absorption, low specific gravity, breathability, weak alkalinity, high specific surface area, cation adsorption capacity (CEC), and fermentability. That is, the water absorption of the ALC can promote composting of highly water-containing materials. The breathability and porous structure of the ALC promote aerobic fermentation, and by maintaining the weak alkalinity, aerobic bacteria are activated, which shortens the fermentation period and further promotes the composting of difficult-to-decompose wood-based materials. Furthermore, due to the high specific surface area, it can adsorb odorous components such as ammonia, and can retain fertilizer components such as cationic substances and phosphoric acid to prevent them from flowing out. In addition, the aerobic fermentation can prevent the occurrence of sanitary pests.

The bedding for farm animals of the present invention is a mixture containing paper sludge and the above-mentioned crushed ALC material, and is manufactured by preparing a mixture whose pH, measured by a specified method, falls within the above-mentioned range. Furthermore, by preparing such a mixture, bacterial growth in the bedding for farm animals containing paper sludge can be suppressed. The bedding for farm animals may contain other components in addition to the paper sludge and crushed ALC material. The specific composition of the paper sludge, crushed ALC material, other components, and pH are as described above.

The following examples are provided to further explain the embodiments of the present invention. However, the present invention is not limited to the following examples.

1. pH
Measurements were made using a pH meter in accordance with "2. Soil chemistry 2-1. Soil pH" in the Ministry of Agriculture, Forestry and Fisheries'"Ibaraki Prefecture Soil and Crop Nutrition Diagnostic Manual I. Soil Analysis Methods." Specifically, the following is done:

[pH Measurement]
Distilled water was added in an amount 2.5 times the mass of the animal litter in a thermostatic chamber at 23° C., and the mixture was shaken at 100 rpm for 30 minutes. A glass electrode was immersed in the resulting suspension, and the pH was measured 30 seconds later.

2. Moisture content: 100 g of paper sludge was dried at 105° C. for 24 hours, and the moisture content was calculated from the mass loss.

3. Water absorption rate: Measured according to the "C. Hilgard method" in "New revised edition of Agricultural Chemistry Experiment Book (revised edition), Vol. 1, Part 4, Soil Experiment Methods, Section 7, Soil Moisture, 4. Water Capacity."

4. Bulk specific gravity: Using a 100 mL measuring cylinder with a 1 mL graduation, the bulk specific gravity was calculated from the mass of the animal litter filled into the measuring cylinder.

5. Thermal Conductivity: Measured in accordance with JIS A 1412-2:1999 "Method of measuring thermal resistance and thermal conductivity of thermal insulation materials - Part 2: Heat flow meter method (HFM method)".

6. Moisture release property A sample was saturated by absorbing water for 1 hour, and then left to stand for 5 days in a thermostatic chamber at 23° C. and a humidity of 50%. The moisture release property was calculated from the amount of moisture lost.

The raw materials used in this example are as follows:
1) Crushed ALC: Crushed ALC having a _D10 of 1.0 mm and a _D90 of 3.7 mm 2) Wet papermaking sludge (wet PS)
3) Dried paper sludge (dried PS)
4) Biomass ash: Fly ash (pH 12.97) from a biomass power generation facility that uses a circulating fluidized bed furnace.
5) Sawdust: used on farms

The physical properties of the raw materials used in this example are shown in Table 1.

Examples 1 to 11 and Comparative Example 1
The components shown in Table 1 were mixed in a 5-liter Hobart mixer (manufactured by Hobart Japan Co., Ltd.) at low speed for 1.5 minutes and high speed for 1.5 minutes to obtain samples. The physical properties of the samples were then measured. The results are shown in Table 2. In Table 2, the "inner proportion" of the crushed ALC material refers to the proportion of the material in the total amount of the crushed ALC material and PS, and the "outer proportion" of the additive refers to the proportion of the material added in the total amount of the crushed ALC material and PS.

From Table 2, it can be seen that all of the pet bedding materials in this example have a pH in the range of 9 to 11, and not only do they inhibit bacterial growth, they also have sufficient water absorption properties.

Claims (6)

Dried paper sludge;
and crushed lightweight cellular concrete.
The litter for farmed animals has a pH of 9 to 11 when a suspension containing 2.5 times the mass of the litter for farmed animals and distilled water is added thereto. 2. The bedding material for farm animals according to claim 1, wherein the crushed lightweight cellular concrete has a particle diameter _D10 of 1 mm or more and a particle diameter _D90 of 4 mm or less. The bedding material for farmed animals according to claim 1 or 2, further comprising biomass ash. Dried paper sludge;
and crushed lightweight cellular concrete, wherein the mixture is added with 2.5 times the mass of distilled water to produce a suspension having a pH of 9 to 11. Dried paper sludge;
and crushed lightweight cellular concrete, wherein the pH of a suspension obtained by adding 2.5 times the mass of distilled water to the mixture is 9 to 11.
A method for inhibiting bacterial growth in animal bedding containing paper sludge. The method of claim 5, wherein the bacteria is one or more bacteria selected from gram-positive bacteria and gram-negative bacteria.