JPH0798710B2 - Method for producing organic fertilizer - Google Patents

Description

Detailed Description of the Invention

[Field of Industrial Application] The present invention relates to a method for producing an organic fertilizer by fermenting various organic substances such as sludge having a high water content, livestock excrement, and fish and shellfish waste to form a compost. [Prior Art] Sewage, industrial wastewater, sludge such as human waste, and excrement of livestock among organic substances have a water content of 70% by weight or more, and are difficult to ferment as they are, and sufficient composting is difficult. However, if these organic substances are also mixed with porous calcium silicate hydrate to adjust the water content to 50 to 60% by weight and then subjected to fermentation treatment, fermentation is promoted, so that composting can be performed ( For example, JP-A-60-36389). Since sewage, industrial wastewater, human waste, etc. have a water content of 95% by weight or more, use a flocculant such as lime to make sludge with a water content of 80 to 90% by weight, and then mix the porous calcium silicate hydrate. It is common to do. [Problems to be Solved by the Invention] However, when the fermentation treatment as described above is performed, the following problems occur. In order to adjust the high water content of the organic substance to 50 to 60% by weight, it is necessary to mix a large amount of porous calcium silicate hydrate. As a result, since the content of organic substances in the mixture is relatively reduced, the fermentation temperature during the fermentation process is unlikely to rise, and the composting period is extended. In addition, it may not satisfy the manufacturing standards for sewage sludge compost (an index of the Sewage Sludge Resource Utilization Council), "keeping the fermentation temperature at 65 ° C or higher for 48 hours or longer". For the same reason as above, the content of organic matter in the organic fertilizer produced by the fermentation treatment is also very small, and therefore when the organic fertilizer is applied to soil, the effect of compost cannot be expected. When a large amount of calcium-containing organic matter such as sludge dehydrated by using lime as a coagulant is mixed with a large amount of porous calcium silicate hydrate and composted, the calcium content in the organic fertilizer becomes extremely high. Therefore, the continuous use of the organic fertilizer may cause a problem of salt accumulation in soil. Especially, continuous use in the house is a problem. The present invention is intended to provide a high-quality organic fertilizer, which has a high fermentation temperature and can not only perform sufficient fermentation treatment in a short period of time but also is rich in organic matter and does not cause accumulation of salts in soil. There is. [Means for Solving the Problems] In order to achieve the above object, the method for producing an organic fertilizer according to the present invention has a particle size of 3 m with respect to an organic matter having a water content of 70% by weight or more.
Mixing porous calcium silicate hydrate having a porosity of 50% or more and m or more so that the water content of the mixture is 50 to 75% by weight, and a fermentation treatment step of fermenting the organic matter, and the fermentation treatment step. The resulting mixture was screened and classified into an organic matter having a low content of porous calcium silicate hydrate and a porous fertilizer residue porous calcium silicate hydrate. Further, it is possible to provide a returning step for returning the residual porous calcium silicate hydrate recovered in the sizing step to the fermentation processing step. [Function] Even if the organic substance has a water content of 70% by weight or more, if the porous calcium silicate hydrate having a particle size of 3 mm or more and a porosity of 50% or more is mixed as described above, the fermentation temperature is increased in the fermentation process. It is possible to perform sufficient fermentation treatment in a short period of time.
This is due to the following actions. This porous calcium silicate hydrate effectively carries a lot of air into the mixture. This porous calcium silicate hydrate effectively absorbs the water content of organic substances. A large number of voids of this porous calcium silicate hydrate are inhabited by microorganisms, which creates an atmosphere in which it is easy to act. In particular, the surface of the porous calcium silicate hydrate, which is in contact with organic matter, creates the state in which microorganisms are most likely to be active. This porous calcium silicate hydrate neutralizes the organic acid generated during the fermentation process and buffers the pH, so the pH of the mixture is
Is maintained in a slightly alkaline state suitable for fermentation. In addition, since a porous calcium silicate hydrate with a particle size of 3 mm or more is used, the mixture is sieved in the sizing step to reduce the content of porous calcium silicate hydrate in the organic fertilizer and the residual porosity. Easy and reliable sizing with high quality calcium silicate hydrate. This is because the particle size difference between the porous calcium silicate hydrate and the organic substance is large. Although the sized organic fertilizer becomes a product, since the organic fertilizer has a high content of organic substances, the fertilizing effect when applied to soil is enhanced and the fertilizer value is increased. Also, in the organic fertilizer, a small amount of porous calcium silicate hydrate powder crushed in the fermentation treatment process and the sizing process remains, but since the content is low, it may cause salt accumulation in soil. Absent. In addition, since many microorganisms inhabit the residual porous calcium silicate hydrate recovered in the sizing process due to the previous fermentation processing step, this porous calcium silicate hydrate is used in the fermentation processing step. When it is returned to and reused, this microorganism is directly carried into the next mixture. Therefore, in the next fermentation process, the activity of the mixture increases in the early stage,
The fermentation process can be performed for a shorter period of time. [Examples] The present invention uses an organic substance having a water content of 70% by weight or more as one of the raw materials, and examples of such an organic substance include sewage, industrial wastewater, sludge such as human waste, cow manure, pig manure, chicken manure and the like. Examples include livestock excrement, seafood waste, and various other organic substances. When sewage, factory wastewater, human waste, etc. are used here, the water content of these is high at 95% or more, so as a pretreatment, a coagulation treatment that weakens the freshness of solids and water to coagulate and dehydrate. is necessary. This aggregation step can be performed by a known method and device. Examples of the aggregating agent used for the aggregating treatment include inorganic aggregating agents such as lime and iron, and organic aggregating agents such as polyacrylamide. As the porous calcium silicate hydrate used in the present invention, for example, a silicic material such as silica and a calcium oxide material such as lime cement are mixed, hardened, and cured under high pressure and high temperature steam by a known method. An inorganic porous artificial mineral can be mentioned. As a specific component, one or two of tobermorite, xonotlite, C-S-H gel, fossiajite gyrolite or hireptandate.
The thing which has a seed or more as a main component can be mentioned. However, the composition ratio of the SiO ₂ content to the CaO content and other trace components are not limited. The above-mentioned porous calcium silicate hydrate is required to have a particle size of 3 mm or more, preferably 3 to 20 mm. This is because if the particle size is less than 3 mm, the fermentation temperature does not rise so much in the fermentation treatment process, the sizing process becomes difficult, and the yield of the porous calcium silicate hydrate deteriorates. On the other hand, when the particle size exceeds 20 mm, the contact area with the organic matter decreases in the fermentation treatment step, and the water content adjusting function deteriorates, which makes fermentation difficult. The above-mentioned porous calcium silicate hydrate is a porous one having a large number of fine voids with a porosity of 50% or more, preferably 65 to 80%. This is because microorganisms inhabit the large number of voids to create an atmosphere in which it is easy to activate. The mixing ratio of the porous calcium silicate hydrate is such that the water content of the mixture of the organic substance and the porous calcium silicate hydrate is 50 to 75.
The ratio is such that it becomes weight%. Moisture content of 50 to 60 for fermentation
Needless to say, weight% is suitable, but in the present invention, since porous calcium silicate hydrate having a particle size of 3 mm or more is mixed, sufficient fermentation is possible even at a high water content of 60 to 75% by weight. It can be performed. The organic substance and porous calcium silicate hydrate are mixed by a known method. The mixing conditions are not limited, but it is general to mix at a room temperature for 5 minutes to 5 hours, preferably 30 minutes to 3 hours by using various known mixers such as a ribbon blender and a rotary mixer. Although the mixing mode is not limited, for example, it is common to gradually add the organic substance to the porous calcium silicate hydrate charged in the mixer all the way under stirring. The mixture of organic matter and porous calcium silicate hydrate is then subjected to a fermentation treatment. Fermentation conditions are not limited, but it is common to ferment using a known fermenter or to deposit on the ground to ferment. In addition, performing aeration or turning back during the fermentation process is also effective in promoting fermentation. However, since the porous calcium silicate hydrate carries a large amount of air through the voids, the frequency of aeration and the like may be low. When the fermentation process is started, the fermentation temperature rises, and sufficient fermentation process can be carried out in a short period of time. This is the next ~
By the action of. This porous calcium silicate hydrate effectively carries a lot of air into the mixture. This porous calcium silicate hydrate effectively absorbs the water content of organic substances. A large number of voids of this porous calcium silicate hydrate are inhabited by microorganisms, which creates an atmosphere in which it is easy to act. In particular, the surface of the porous calcium silicate hydrate, which is in contact with organic matter, creates the state in which microorganisms are most likely to be active. This porous calcium silicate hydrate neutralizes the organic acid generated during the fermentation process and buffers the pH, so the pH of the mixture is
Is maintained in a slightly alkaline state suitable for fermentation. Then, the mixture that has been subjected to the fermentation treatment is subjected to a sizing step, and is classified by sieving into an organic fertilizer having a low content of porous calcium silicate hydrate and the remaining porous calcium silicate hydrate. Here, in the present invention, since the porous calcium silicate hydrate having a particle size of 3 mm or more is used, the particle size difference between the porous calcium silicate hydrate and the organic substance is large, and the mixture can be easily and surely separated. Can be granulated. The sized organic fertilizer becomes a product, but since the content of organic substances in the organic fertilizer is high, the fertilizing effect when applied to soil is enhanced and the fertilizer value is increased. Also, in the organic fertilizer, a slight powder of porous calcium silicate hydrate crushed in the fermentation process and the sizing process remains,
Since its content is low, it does not cause salt accumulation in soil. Then, a return step of returning the residual porous calcium silicate hydrate (hereinafter referred to as recovered calcium silicate hydrate) recovered in the sizing step to the fermentation treatment step and reusing it can be added. The recovered calcium silicate hydrate has many microorganisms inhabited by the previous fermentation treatment step, so when this porous calcium silicate hydrate is reused by returning it to the fermentation treatment step, it becomes the next mixture. This microorganism is brought in as it is. Therefore, since the activity of the mixture is increased in the initial stage of the next fermentation treatment, the fermentation treatment can be carried out in a shorter period of time. Next, examples embodying the present invention will be described with reference to the drawings in comparison with comparative examples.

[Raw materials]

Sewage sludge with a water content of 84% by weight was used as the organic matter. This sewage sludge has a water content of 95-97 as shown in FIG.
The sewage (weight%) is put into the aggregator 1 together with the aggregating agent (lime), and the agglomerates are passed through the dehydrator 2 to prevent dehydration up to a water content of 84%. As the porous calcium silicate hydrate, Escariu (trade name of the same company) of Onoda STEC Co., which contains tobermorite as a main component, was used. Its water content is about 15%.

[Mixing ratio]

100 kg of sewage sludge was mixed with 20 kg of Escariu having different particle sizes as shown in Table 1, and Comparative Example 1, Comparative Example 2 and Example 1
And Example 2 were set. Therefore, the water content of each of these mixtures is about 72.5%.

【mixture】

As shown in FIG. 1, mixer 3 (rotary mixer)
The porous calcium silicate hydrates (Escariu) of the respective Examples and Comparative Examples were separately added to the above, and sewage sludge was gradually added to them under stirring and kneading.

[Fermentation process]

Fermenter with an internal volume of 200 lined with Styrofoam 4
Then, each of the above-mentioned mixtures was immediately added after kneading to start the fermentation treatment. In addition, using the stirring device provided in the fermentation tank, cutting was performed once a week from the day when the fermentation treatment was started. This fermentation treatment period is about one month.

[Measurement and analysis results]

FIG. 2 shows the change with time in the fermentation temperature during the fermentation process in Example 1. The fermentation temperature of Example 1 started to increase after about 1 day from the start of the fermentation treatment, reached the maximum temperature after about 3 days, and gradually decreased after the 5th day. FIG. 3 shows the maximum fermentation temperature in Example 1, Example 2, Comparative Example 1 and Comparative Example 2. The maximum fermentation temperature of each of Example 1, Example 2 and Comparative Example 2 exceeded 65 ° C., which satisfied the above-mentioned production standard for sewage sludge compost. On the other hand, in Comparative Example 1, the fermentation temperature started to rise slowly, and the maximum fermentation temperature was low at about 56 ° C. After the fermentation treatment for about 1 month was completed, Example 1, Example 2 and Comparative Example 2 were almost composted after the fermentation was sufficiently completed. However, in Comparative Example 1, the fermentation was insufficient, and the odor was stronger and sticky compared to the others.

[Sizing process]

After air-drying each mixture of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 which has undergone the fermentation treatment step as described above,
As shown in FIG. 1, by sieving with a 3 mm sieve 5, the organic fertilizer having a low content of porous calcium silicate hydrate and the residual porous calcium silicate hydrate were sized. However, in Comparative Example 1 and Comparative Example 2 in which a porous calcium silicate hydrate having a particle size of less than 3 mm was mixed, the sizing was hardly performed. In Example 1 and Example 2 in which a porous calcium silicate hydrate having a particle size of 3 mm or more was mixed, the sizing was easily and reliably performed.

[Fertilizer component]

Table 2 shows the fertilizer components of each organic fertilizer after the sizing. Examples 1 and 2 are rich in total nitrogen and total carbon. This is because the sizing was effectively performed and the content of organic substances was increased. On the other hand, in Comparative Examples 1 and 2, total nitrogen and total carbon are small, and CaO is large. This is because the sizing was hardly performed and the content of organic substances did not increase.

[Return process]

As shown in FIG. 1, the residual porous calcium silicate hydrate obtained by sizing in Example 1 was air-dried to obtain a recovered calcium silicate hydrate having a water content of 15% by weight. Example 3 was set by mixing 20 kg of the recovered calcium silicate hydrate and 5 kg of new porous calcium silicate hydrate (grain size 3 to 5 mm) with 100 kg of the sewage sludge. FIG. 2 shows the change with time in the fermentation temperature when the fermentation treatment was carried out in the same manner as in Example 1 in Example 3. In Example 3,
Fermentation temperature begins to rise 15 hours after the start of fermentation treatment,
It was 10 hours faster than in Example 1. This indicates that the microbes inhabiting the recovered calcium silicate hydrate enhanced the initial activity of the mixture. [Advantages of the Invention] The present invention, which is configured as described above, has the following advantages. According to the method for producing an organic fertilizer according to claim 1, not only can the fermentation temperature increase and a sufficient fermentation treatment can be carried out in a short period of time, but also the content of organic matter is high and the accumulation of salts in the soil does not occur. High-quality organic fertilizer can be produced. According to the method for producing an organic fertilizer according to claim 2, in addition to the above effects, the fermentation treatment period can be further shortened.

[Brief description of drawings]

FIG. 1 is a process chart of an example of the present invention, FIG. 2 is a graph showing the change of fermentation temperature with time, and FIG. 3 is a graph showing the maximum fermentation temperature of Examples and Comparative Examples. 3 ... Mixer, 4 ... Fermenter, 5 ... Sieve.

Claims (2)

[Claims] 1. An organic substance having a water content of 70% by weight or more,
Mixing porous calcium silicate hydrate having a particle size of 3 mm or more and a porosity of 50% or more so that the water content of the mixture is 50 to 75% by weight, and a fermentation treatment step of fermenting the organic matter, and the fermentation treatment. Manufacture of organic fertilizer consisting of sieving the mixture that has passed through the steps and sizing to separate organic fertilizer with low content of other porous calcium silicate hydrate and residual porous calcium silicate hydrate Method. 2. The method for producing an organic fertilizer according to claim 1, further comprising a return step of returning the residual porous calcium silicate hydrate recovered in the sizing step to the fermentation treatment step.