JP4633222B2 - Organic waste treatment methods - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for composting organic waste such as food waste, sludge and manure mixed with plastic products by fermentation and drying.
[0002]
[Prior art]
Organic waste such as garbage, sludge, manure, etc. can be treated with microorganisms relatively easily and can be reduced by microbial treatment. It is possible to recycle as such. In recent years, microbial treatment of organic waste has been actively performed due to the reduction of waste landfill and the review of organic cultivation in agriculture.
[0003]
In addition, various bags, sheets, tools, etc. that were conventionally manufactured using plastics that cannot be decomposed by microorganisms can also be separated from biodegradable plastics for the purpose of facilitating microbial treatment. What was manufactured as a raw material has come to be used.
[0004]
There are various types of biodegradable plastics, but in general, it is desired that those that are difficult to decompose during use and easily decompose in the process. On the other hand, in the composting treatment, a temperature of 60 ° C. or higher usually lasts for several days, and very active microbial degradation is performed. Therefore, composting organic waste containing biodegradable plastic products can be said to be a very effective treatment method.
[0005]
[Problems to be solved by the invention]
However, some biodegradable plastic products are very slow to decompose at a temperature of about 60 ° C., and depending on the processing conditions for composting, the high temperature may not be sufficiently maintained. Also, in the case of so-called garbage processing machines that are most likely to be mixed with biodegradable products such as garbage bags, and are related to household or commercial waste, the temperature during processing is often 60 ° C or less. In addition, since the processing time is short, there is a problem that the biodegradable plastic product cannot actually be processed sufficiently. When organic waste containing biodegradable plastic products is treated with such a treatment device, not only the biodegradable plastics that are mixed in cannot be treated, but also the biodegradable plastic products are When using garbage bags made of biodegradable plastics, the organic waste in the bags was not treated properly, causing anaerobic decomposition and causing odors. .
[0006]
The object of the present invention is to provide a method for efficiently composting organic waste mixed with biodegradable plastic products.
[0007]
[Means for Solving the Problems]
The present inventors have, when such circumstances result of intensive studies looking Kan, the microbial decomposition treatment at 70 ° C. below the temperature of organic waste garbage or the like including a biodegradable plastic product, 75 ° C. The present inventors have found that the treatment can be suitably performed by incorporating a process for 1 to 48 hours under a high temperature condition of 90 ° C. or less and a high humidity of 100% relative humidity .
[0008]
That is, the present invention relates to a treatment tank for storing organic waste mixed with a biodegradable plastic product, a blower for sending air into the treatment tank, and a heating facility capable of heating the inside of the treatment tank. In a method for treating organic waste mixed with biodegradable plastic products using an organic waste treatment apparatus comprising The gist of the present invention is a method for treating organic waste, characterized by comprising a step of disintegrating a plastic product.
[0009]
Hereinafter, the present invention will be described in detail.
The biodegradable plastic product referred to in the present invention is not particularly limited as long as it is a product formed of a biodegradable resin. Specifically, a film, a sheet, a bag, a string, a band, a box In addition to these, various tableware such as chopsticks, forks, spoons and dishes, and clothing such as clothes and hats.
[0010]
The raw materials for biodegradable plastic products include polypeptides such as collagen, gelatin, fibrin, albumin, synthetic polypeptide, silk and wool, amylose, dextran, alginic acid, chitin, chitosan, cotton, hemp, rayon and cellulose. Sugars, polyglycolic acid, polylactic acid, polyglactin, polymalic acid, poly-ε-caprolactone, poly-3-hydroxybutyric acid, poly-3-hydroxyvaleric acid, poly-4-hydroxybutyric acid, poly-6-hydroxyhexanoic acid, Examples thereof include polyesters such as polybutylene succinate and polyethylene succinate, and are particularly effective for products mainly made of polylactic acid.
[0011]
The organic waste as used in the present invention is not particularly limited as long as it can be microbially decomposed with organic waste, but waste generated from households, restaurants, etc., processing residuals discharged from food processing plants, Examples include organic sludge and livestock excrement generated by wastewater treatment.
[0012]
The organic waste processing apparatus used in the processing method of the present invention may be a so-called garbage processing apparatus. At least a processing tank for storing organic waste, and a blower for sending air into the processing tank And a heating facility capable of heating the inside of the treatment tank, and further preferably provided with a stirring means capable of stirring the inside of the treatment tank.
[0013]
Among these, the treatment tank is not particularly limited as long as it can accommodate organic waste, and the capacity and material are not particularly limited, but in the present invention, it is necessary to heat the inside of the treatment tank. is preferably 10L least 5 m ³ or less, more desirably at 20L than 1 m ³ or less, the material can that withstand high temperatures, it is desirable to use a strong material, such as stainless and heat-corrosion resistant plastic corrosion .
[0014]
The blower need not be special, as long as the contents are not anaerobic and have sufficient capacity for drying. The amount of air supply varies between the process that mainly focuses on the degradation of biodegradable plastics and the process that mainly fermentations and decomposes organic waste, but it is 0.1 to 10 m ³ / min per 1 m ³ treatment tank. If it is.
[0015]
As the heating equipment, the tank itself may be heated or heated, or the air in the tank may be heated to raise the temperature in the tank.
[0016]
The stirring means is not particularly limited as long as the contents can be sufficiently stirred, and may be those generally used in organic waste treatment apparatuses. Specifically, an apparatus in which a stirring blade is provided on the rotary shaft of the rotary motor can be mentioned. By stirring by this stirring means, the contents are stirred, aerobic fermentation occurs, and suitable drying is performed.
[0017]
In addition, a special degrading bacterium may be added to the treatment, but even if it is not particularly added, the treatment can be sufficiently performed by the bacteria attached to the garbage or the floating bacteria in the air. In particular, in the case of so-called continuous processing in which the next treatment is performed in a state where the processed material left in the processing tank remains in the processing tank, the effect of adding degrading bacteria is small.
[0018]
In addition, sawdust, bark, rice husk, zeolite, wood chips, rice bran, or other special agents may be used as a water conditioner, fermentation base, or fermentation aid, but it is also possible to treat with only garbage. is there.
[0019]
In the present invention, the step of mainly disintegrating the biodegradable plastic product is a step of setting the internal temperature of the tank to 75 ° C. or higher and 90 ° C. or lower while maintaining the relative humidity at 100% . The main purpose of this process is to break down the biodegradable plastics that are mixed in, and to facilitate microbial degradation in the process of mainly decomposing organic waste. When processing ordinary organic waste, the relative humidity in the tank at the initial stage of processing is 90% or more, and it is not necessary to add water. However, when processing a fairly dry one or when performing a process of mainly decomposing organic waste first, it may be necessary to add moisture to increase the relative humidity.
[0020]
It is desirable to keep in mind that the amount of air supplied in this process maintains a relative humidity of 90% or more and does not become anaerobic. Preferably the processing tank per 0.1~2m ³ / min of 1 m ³ in particular, 0.2~1m ³ / min is more preferable. In addition, air can be supplied from anywhere as long as it is in the tank, but it is desirable to perform air supply from the bottom of the tank or the back side of the stirring blade in order to spread the air throughout. By performing such high-temperature and high-humidity treatment, the biodegradable plastic is efficiently disintegrated.
[0021]
The processing time of the step of mainly disintegrating the biodegradable plastic product requires 1 to 48 hours . Long-term treatment at high temperatures is effective for the degradation of biodegradable plastics, but it hinders the degradation of organic waste by microorganisms and the degradation of biodegradable plastics mainly in the process of decomposing organic waste. It is for bringing about.
[0022]
The term “collapse” as used herein means that the biodegradable plastic has a low molecular weight due to hydrolysis or the like, the strength is remarkably lowered, and the shape cannot be maintained, and does not mean degradation of the monomer itself.
[0023]
In the present invention, the step of mainly decomposing organic waste requires a temperature suitable for a microbial reaction of 70 ° C. or lower, specifically 30 ° C. or higher and 70 ° C. or lower , preferably 40 ° C. or higher and 65 ° C. or lower. This is a step of degrading the biodegradable plastic that has collapsed in the step of collapsing organic waste and mainly biodegradable plastic products at a temperature of ℃ or lower. Since the biodegradable plastic collapses and has a low molecular weight mainly in the process of disintegrating the biodegradable plastic product, it is easily decomposed in this process. Moreover, since organic waste is also susceptible to microbial degradation by treatment under high-temperature and high-humidity conditions, the treatment becomes easy.
[0024]
Air amount in this step is slightly raised, preferably 0.2 to 10 m ³ / min per treatment tank 1 m ^3, more preferably to 0.5 to 5 m ³ / min. However, when a drying step is provided as a third step, the operation may be performed in the same manner as the step of mainly disintegrating the biodegradable plastic product. In addition, when the moisture content of the processed product is sufficiently high, or when the moisture content in the tank is not significantly reduced even if the air supply amount is increased, the air supply amount may be further increased.
[0025]
The microbial decomposition treatment time in this step is preferably 6 hours or more, and more preferably 8 hours or more when the moisture content of the treated product is 80% or less, desirably 70% or less and not less than 30%. desirable. This is because if the water content of the treated product is high, good aerobic treatment cannot be performed, and if it is less than 30%, the microbial activity is significantly reduced.
[0026]
In the present invention, it is necessary to mainly perform a step of decomposing organic waste after performing a step of disintegrating the biodegradable plastic product. When processing garbage containing biodegradable plastic products continuously, it may be performed in reverse.
In that case, the biodegradable plastic product does not collapse in the first step, that is, mainly the step of decomposing organic waste, but it is collapsed by the next step of mainly degrading the biodegradable plastic product and is continuously In the next cycle, the biodegradable plastic product does not accumulate in the tank, and it can be processed well because it is effectively decomposed mainly by the process of decomposing organic waste. .
[0027]
【Example】
Hereinafter, the present invention will be specifically described.
Reference example 1
The following experiment was conducted to investigate the collapse behavior of biodegradable plastics. A film composed of 80 parts by weight of polylactic acid and 20 parts by weight of Bionole manufactured by Showa Polymer Co., Ltd., 17 parts by weight of acetyltributyl citrate as a plasticizer, and 5 parts by weight of silicon oxide (SiO ₂ ) No. 11-116788 (see Example 1) was allowed to stand at 60 ° C., 70 ° C., and 80 ° C. under conditions of relative humidity of 90% and 100%. After returning to room temperature after 1, 2, 3, 6, 24, and 48 hours and air-drying, the degree of deterioration / disintegration was visually determined, and the molecular weight of the monomer was measured. At 60 ° C. and 70 ° C., there was no change in appearance at all treatment times at both 90% and 100% relative humidity. The molecular weight was almost unchanged at 60 ° C. until 24 hours, but decreased slightly in the treatment at 100% relative humidity, 70 ° C. and 24 hours, and after 48 hours, it decreased slightly in the 60 ° C. treatment. When the treatment temperature is 80 ° C, the flexibility is lost after 2 hours at 100% relative humidity, the deterioration is observed after 6 hours, and the shape of the bag cannot be maintained after 24 hours, and it is broken into pieces. Became. When the relative humidity was 90%, the collapsed state was worse than that of the relative humidity of 100%, and although the deterioration occurred even after 24 hours, the bag shape was maintained. Figure 1 shows the change in molecular weight when treated at 80 ° C with 100% relative humidity. It became clear that hydrolysis occurred with the treatment time and the molecular weight decreased rapidly.
[0028]
Example 1
10 bags containing 1kg of cocoon in a garbage bag made by thermocompression bonding of the film produced in the same way as in the above reference example, have a stirring blade, can be fed from the bottom of the treatment tank, and the inside of the tank is added It was put into a heatable garbage processing machine (processing capacity 20L). 200g of seed compost was added to the treatment tank in advance. After throwing in the soot, air was supplied at 10 L / min with the stirring blade stopped, and the inside of the tank was heated to 80 ° C. At this time, the relative humidity in the tank was 100%. After 5 hours, the treatment tank temperature was lowered to 60 ° C., the air supply amount was changed to 20 L / min, and the treatment was further performed for 24 hours while stirring at 1 rpm. The biodegradable plastics collapsed significantly during the treatment at 80 ° C for 5 hours, and the subsequent agitation at 60 ° C allowed the organic waste and the collapsed biodegradable plastics to mix well, allowing good fermentation. . The water content of the processed product after the test was 40%, which was a smooth fermented processed product.
[0029]
Comparative Example 1
As in Example 1, 10 biodegradable garbage bags containing 1 kg of straw have a stirring blade, can feed air from the bottom of the treatment tank, and can heat the inside of the garbage treatment machine (processing capacity 20L) ). 200g of seed compost was added to the treatment tank in advance. After charging, the air was fed at 10 L / min while the stirring blade was stopped, and the inside of the tank was heated to 60 ° C. At this time, the relative humidity in the tank was 100%. After 5 hours, the air supply rate was changed to 20 L / min, and a further 24 hours of treatment was performed while stirring at 1 rpm. After the test was completed, the garbage bags in the tank remained the original shape, and a part of them was entangled with the stirring blades. In addition, some garbage bags had no contents outside, and the garbage was not treated well among them, causing corruption.
[0030]
【effect】
According to the present invention, organic waste mixed with biodegradable plastics can be efficiently and sufficiently fermented, and the resulting compost is also good.
[Brief description of the drawings]
FIG. 1 is a graph showing changes in molecular weight in a biodegradable film disintegration process (100% relative humidity, 80 ° C. treatment).

Claims (1)

Organic having a treatment tank for storing organic waste mixed with biodegradable plastic products, a blower for sending air into the treatment tank, and a heating facility capable of heating the treatment tank In a method for treating organic waste mixed with biodegradable plastic products using a toxic waste treatment apparatus, the relative humidity in the treatment tank is 100%, and the temperature is between 75 ° C. and 90 ° C. for 1 hour. After performing the step of mainly disintegrating the biodegradable plastic product that is maintained for ˜48 hours, the step of performing the fermentative decomposition of organic waste mainly having a temperature in the treatment tank of 30 ° C. or higher and 70 ° C. or lower is performed. An organic waste processing method characterized by the above.

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