JPH0657628B2 - Composting method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for composting plant bodies such as rice straw and water hyacinth.

Conventional technology and its problems Conventionally, when composting a plant such as rice straw, it does not ferment well by itself, so cow dung is added or lime titanate is added for the purpose of adjusting the C / N ratio. It was Since the amount to be added has been empirically determined, there are drawbacks such as insufficient fermentation and a very long time until fermentation is completed.

Means for Solving the Problems When water plants such as water hyacinth are cut and dried, and a readily decomposable organic substance is added for composting, the mixture has a water content of 40 to 63% and a bulk specific gravity of 0.2 to 0. 6 is needed and it is important to provide adequate nutrition.

When BOD ₅ was considered as an indicator of this nutrient source and the effect of BOD _{5 of} the mixture on fermentation was examined, it was found that the mixture B
There is a close relationship between OD ₅ and fermentation temperature, and in order to carry out aerobic fermentation in a short period, the mixture BOD ₅ should be at least 4 times.
It is required to be 5 mg-O ₂ / g-DS or more.

The present invention pays attention to this, and in aerobically fermenting field residues, agricultural wastes, or aquatic plants in a short period of time, when mixing raw material plants and additives, the respective water contents and BO
Based on the value of D ₅ , the water content of the mixture is 40 to 63% (preferably 45 to 60%), and the BOD _{5 of} the mixture is 45 m.
The mixing ratio is set so as to be g / g or more, and the bulk specific gravity of the mixture at the time of mixing is 0.2 to 0.6 (preferably 0.2).
After mixing so as to be 5 to 0.5), the essential point is to ferment by performing forced aeration. Hereinafter, the present invention will be described with reference to examples.

Example 1 Water hyacinth that was dried after cutting was used as a raw material, and as additives, sludge and sludge compost, chicken dung, beef dung, and rice bran were mixed at various ratios and charged into a 500-volume fermenter. Aeration was carried out from the lower part of the fermenter with upward flow, and fermentation was carried out for about 3 weeks. Based on the fermentation process for each condition, the relationship between the water content of the mixture and the maximum temperature during the fermentation period is summarized in FIG. Further, FIG. 2 shows the relationship between the mixture BOD ₅ and the time for which a high temperature of 50 ° C. or higher was maintained.

When composting, it is necessary to achieve (1) sterilizing pathogens and parasites and sanitizing them, and (2) promoting and stabilizing the decomposition of organic substances to improve their handleability. I have to. The most obvious indicator for these two purposes is the fermentation temperature, which is generally (1)
For, high-temperature fermentation of 60 ~ 65 ℃ or more,
Regarding (2), it is considered that the object can be achieved by keeping 50 to 65 ° C., which has high microbial activity, for a long time (120 hours or more).

From FIG. 1, it is possible to achieve high temperature fermentation at 60 ° C. or higher by setting the water content of the mixture to 40 to 63%. In particular, when an organic matter containing pathogens such as sludge and animal dung or a large amount of parasites is added as an additive, the water content of the mixture is preferably 45 to 60% from the viewpoint of maintaining the high temperature.

Next, from FIG. 2, the mixture BOD ₅ was 45 mg-O _2.
/ G-DS or more, all above 50 ℃ 120hr
It is understood that sufficient fermentability can be obtained by maintaining the above. On the contrary, when the mixture BOD ₅ is 45 mg-O ₂ / g-DS or less, fermentability rapidly deteriorates, and it becomes difficult to reach a fermentation temperature of 50 ° C or higher. And these trends are
Both FIG. 1 and FIG. 2 have no relation to the types of raw materials and additives.

Due to the above, when the plant material and the additive are mixed, the water content of the mixture is 40 to 63%, preferably 45 to 60%, and the mixture ratio is adjusted so that the mixture BOD ₅ is 45 mg-O ₂ / g-DS or more. By setting, active aerobic fermentation can be performed in a short period of time.

Example 2 Water hyacinth that was dried after cutting was mixed with 10% by volume of sludge dewatering cake as an additive, the degree of compaction was changed in several stages, and the mixture was put into a 500-volume fermenter and fermented for 2 weeks. Table 1 shows the results of the test.

All the charged mixtures had a water content of 59.8% and a BOD ₅ of 70.5 mg-O ₂ / g-DS, which satisfied the optimum conditions described in Example 1. From Table 1, even under the same mixing conditions, the degree of compaction is small, and therefore, when the mixture has a low bulk specific gravity, sufficient fermentability is obtained even if the water content and BOD ₅ of the mixture satisfy the optimum conditions. I know I can't. That is, it is necessary that the value of the bulk specific gravity is at least 0.2 or more, preferably 0.25 or more.

It is considered that this is because as the bulk specific gravity increases, the amount of heat generated per unit volume increases and the heat storage property improves, but if the bulk specific gravity is too large, the air permeability deteriorates and the mixture Oxygen is no longer supplied to every corner. As the limit of the bulk specific gravity, from the example of composting sludge and the like, the compaction state must be adjusted so that the limit is about 0.6 and preferably 0.5 or less.

When composting a dry plant having a bulk specific gravity of 0.1 or less, such as dried water hyacinth, a bulk specific gravity of 0.2 to 0.6 when the additives are mixed,
It was possible to obtain sufficient fermentability by adjusting the compaction state so that it is preferably 0.25 to 0.5.

Example 3 A slightly dried rice straw was cut into about 20 mm, and either sludge, sludge compost, or dried chicken dung was mixed at various ratios as an additive, and the mixture was put into a 500-volume fermenter and fermented for 8 weeks. The results when the test was conducted are shown in FIGS. 3 and 4.

FIG. 3 shows the relationship between the water content of the mixture and the maximum temperature during the fermentation period. It can be seen that high temperature fermentation is carried out when the water content of the mixture is 40 to 65% (preferably 45 to 60%). Compared to the case of water hyacinth of Example 1, the results show that high temperature fermentation is likely to occur even if the water content is somewhat high. This is because water hyacinth has a water content of 6 in the mixture.
When it exceeds 0%, the volume is rapidly reduced and the air permeability is deteriorated. On the other hand, in the case of rice straw, the fiber is relatively hard and the fiber is not tight, so no rapid volume reduction occurs. , Moisture content 6
It is considered that the air permeability is sufficiently maintained up to about 5%.

FIG. 4 shows the relationship between the mixture BOD ₅ and the time at which the temperature was kept at 50 ° C. or higher. The mixture BOD ₅ was 40 mg-O.
_It can be seen that when the ratio is ₂ / g-DS or more, 50 ° C. or more can be maintained for 120 hours or more.

Compared with the case of water hyacinth of Example 1, it shows a slightly lower limit value, but considering safety, it is preferable that the mixture BOD ₅ is 45 mg-O ₂ / g-DS or more also in the case of rice straw. .

The rice straw used as a raw material has a slightly higher bulk specific gravity than the water hyacinth used in Examples 1 and 2, and has a bulk specific gravity of 0.2 or more when mixed with an additive, and is further consolidated and added. There was no need. However, when the dried chicken dung was used as the additive, the water content of the mixture was 40% or less even if both were mixed, so that water was added for the purpose of adjusting the water content.

Example 4 When fully dried water hyacinth was used as a raw material and slightly dried beef dung was used as an additive, when it was charged into a 500-volume fermenter, Case 1 was mixed by setting a mixing ratio based on the present invention and further consolidated. On the other hand, in Case 2, when fermentation was carried out for 2 weeks without considering the content of the present invention, the fermentation temperature shown in FIG. 5 was obtained. However, the properties of the raw materials and additives are shown in Table 2, and the mixing conditions for cases 1 and 2 are as shown in Table 3.

From FIG. 5, the case 1 in which the mixing was carried out according to the present invention had extremely good fermentability, and it was higher than the case 2 in which 20% (volume ratio) of water hyacinth was simply mixed without considering the content of the present invention. The fermentation temperature is obtained. Regarding the properties of the product, in case 2, the water hyacinth fiber is hard and only 14% of the crude protein is decomposed before the fermentation, whereas in case 1, the water hyacinth fiber is fragile and easily broken. 32% of crude protein due to fermentation
Had decomposed and disappeared.

Although Examples 1 to 4 showed the fermentation state when water hyacinth and rice straw were used as raw materials, when other plant raw materials are used, similarly, according to the present invention, sufficient fermentation can be performed in a short time. It is possible. Especially when using sufficiently dried water hyacinth or straw as a raw material, in order to obtain the optimum conditions of the present invention, water is added to adjust the water content, or compression mixing is performed to adjust the bulk specific gravity, and consolidation is applied. It is necessary to consider taking the measures of.

EFFECTS OF THE INVENTION According to the present invention, therefore, when composting field residues, agricultural wastes, or aquatic plants, fermentation is not carried out by itself, and therefore the water content BOD ₅ of the raw material and the organic additive is used as the basis. , The water content of the mixture is 40 to 63% (preferably 45 to 6).
0%), the mixing ratio is set so that the mixture BOD ₅ is 45 mg / g or more, and the bulk specific gravity of the mixture is 0.2 to 0.6 (preferably 0.25 to 0.5) during mixing. By adjusting the compaction state and performing forced aeration, it is possible to perform sufficient aerobic fermentation in a short period of time.

[Brief description of drawings]

1 is a graph showing the relationship between the water content of the mixture and the maximum temperature, FIG. 2 is a graph showing the relationship between the mixture BOD ₅ and the holding time of 50 ° C. or more, and FIG. 3 is a graph showing the relationship between the water content of the mixture and the maximum temperature. , FIG. 4 shows the mixture BOD ₅ and 50 ° C.
FIG. 5 is a graph showing the relationship between the above holding time and FIG. 5 is a graph showing the relationship between the elapsed days and the fermentation temperature.

Claims (2)

[Claims] 1. The above raw materials and additives in an aerobic fermentation process using field residues such as rice straw and straw, agricultural waste such as mulberry waste tobacco residual stems, and aquatic plants such as water hyacinth and watercress as raw materials. Based on the water content of the easily decomposable organic substance used as a product and the value of BOD ₅ , the water content of the mixture is
40-63%, the mixing ratio is set so that the BOD _{5 of} the mixture is 45 mg-O ₂ / g-DS or more, and the consolidated state is adjusted so that the bulk specific gravity is 0.2-0.6. A method for composting, which comprises performing aerobic fermentation. 2. Claims that use organic waste such as sewage sludge, livestock manure, etc., or compost fermented aerobically from them as raw materials, or bran such as rice, corn, etc. as the easily decomposable organic matter to be added. The method for composting according to item 1.