JP2003211134A - Fermentation method for organic waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fermentation method capable of producing good quality compost having high application safety which does no harm to plants when it is applied to green farmland in a shorter fermentation period compared with a conventional method, downsizing a fermentation tank and facility and realizing reduction of a running cost. <P>SOLUTION: The fermentation method for organic waste is a method for fermenting a mixture of organic waste and chaff. The first fermentation first process 2 in which fermentation lasts for 3-10 days is carried out. All the obtained processed materials are transferred to the second fermentation process 3 in which fermentation lasts for 3-10 days. All the obtained processed materials are transferred to the third fermentation process 4 fermentation lasts for is not more than 30 days. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for fermenting and treating sludge, organic waste such as livestock manure, and garbage.

[0002]

2. Description of the Related Art Conventionally, sludge generated by treatment of wastewater such as sewage, human waste, industrial wastewater, and organic waste such as livestock excrement and garbage have been disposed of by incineration or landfill. However, in recent years, due to social circumstances such as prevention of global warming, reduction of fuel cost, the problem of dioxin generation, and difficulty in securing a final disposal site, re-use as compost has attracted attention.

Compost is an ideal treatment and disposal method that is produced by decomposing organic waste with microorganisms and can be effectively reused by being returned to green agricultural land. However, when compost with insufficient decomposition treatment of organic matter is applied to green agricultural land, there is a problem that the decomposition rate of compost in soil is too fast, and oxygen and nitrogen in the soil are deficient, which damages plants.

In order to avoid the distribution of such defective compost, a manufacturing guideline for compost is provided. For example, in the "Indicator of sewage sludge compost (Part 2)" issued by the Sewage Sludge Resource Utilization Council, as the production criteria of sewage sludge compost, the fermentation period is 10 to 14 days, and the primary fermentation period is 1 to 3 days. The second fermentation of more than a month is specified.
By carrying out the fermentation treatment in accordance with such a production guideline, a compost having a low possibility of damaging a plant when applied, that is, a highly safe application is produced.

[0005]

[Problems to be Solved by the Invention] However, when a facility is constructed in accordance with such a manufacturing guideline, the capacity of the fermenter becomes enormous, and it is necessary to secure a large space site, as well as ventilation and turning back. There is a problem that the required operating cost is high.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a fermentation treatment method for producing compost having high application safety even in a short fermentation period.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has completely divided the fermentation treatment step into two or three steps, and batch-transfers the mixture between the steps. According to the present invention, it was found that a compost with high application safety can be obtained even if the fermentation period is shortened, and the present invention has been completed.

That is, the present invention is a method for fermenting a mixture of organic waste and rice husks, wherein the fermentation first step in which the number of days of fermenting treatment is 3 to 10 days is performed, and the total amount of the obtained treated product is obtained. Is a fermentation treatment method for an organic waste, characterized in that the fermentation treatment is carried out for 3 to 10 days, and preferably the treated product obtained in the fermentation second step The total amount of the
It is characterized in that it is transferred to the fermentation third step which is within a day. Further, preferably, the fermentation treatment method, wherein the fermentation first step is performed in the upper stage of the fermentation tank divided into upper and lower two stages by a partition, and then the fermentation second step is performed in the lower stage of the fermentation tank. In the above fermentation treatment method, the organic waste is organic sludge discharged from the wastewater treatment facility.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. The organic waste in the present invention, sewage, human waste, sludge generated by the treatment of wastewater such as industrial wastewater, dehydrated cake obtained by dehydrating those sludge, livestock excreta, garbage, pruned branches, cut grass and various organic It refers to industrial wastes and other wastes whose main components are organic substances that can be decomposed by microorganisms.

These organic wastes are subjected to fermentation treatment as a mixture in which chaffs are mixed in order to control water content and improve air permeability. The properties of the chaff used are not particularly limited, and raw chaffs generated during hulling, dry chaffs that are dry-smashed with a hammer mill, etc. Etc. are preferably used.

Further, when the organic waste and the rice husks are mixed, it is also possible to mix the fermented product after the fermentation process or the fermented product during the fermentation process. By mixing such a fermented product, the amount of rice husk added can be reduced and seeding of fermenting bacteria can be achieved.

[0012] The organic waste, rice husk and fermented product are preferably mixed so that the water content after mixing is 40 to 80%, more preferably 50 to 70%. When the water content is less than 40%, the water content becomes too low during fermentation, and a good fermentation reaction does not proceed, which is not preferable. Further, when the water content exceeds 80%, good high temperature aerobic fermentation may not proceed, which is not preferable.

The present invention is a method for fermenting a mixture of this organic waste and rice husk, and first, as the first step of fermentation, fermenting treatment is carried out for 3 to 10 days. This fermentation first
In the process, the easily decomposable organic matter contained in the organic waste is rapidly microbially decomposed, so that the temperature of the mixture becomes 65 ° C. or higher. This high temperature environment kills or inactivates pathogenic fungi, parasite eggs, plant seeds, and the like.

The fermentation treatment time required for the first fermentation step varies depending on the organic waste used as a raw material, but is 3 to 1
0 days. If the treatment time is less than 3 days, the process proceeds to the second step of fermentation while leaving a large amount of easily decomposable organic substances, and the fermentation is insufficient and the quality of the product deteriorates. If the treatment time exceeds 10 days, the product quality is not affected, but the treatment tank volume becomes unnecessarily large and it cannot be used.

The fermentation treatment method used in the first fermentation step is not particularly limited, and may be a sedimentation type, a rotary kiln type,
Auger type, vertical multistage type, silo type, bottle type and the like are preferably used.

Fermentation treatment proceeds by leaving a mixture of organic waste and rice husk in a fermentation tank employing these fermentation treatment methods, but for the purpose of promoting the progress of fermentation reaction,
It is preferable to perform stirring and aeration. The stirring method is not particularly limited, in the case of a stacking type, stirring by a shovel car, a conveyor, a crane, etc., in the case of a rotary kiln type, stirring by rotation, etc., in the case of an auger type, stirring by an auger, etc., a vertical multi-stage type In the case of agitating blades that are projected horizontally on the rotating shaft, or by means of agitation such as rake, paddle, gate, etc. and gravity drop, in the case of silo type, crane, pin mixer, agitation by gravity drop, bottle type, etc. In this case, stirring with a scoop or paddle is preferably used.

Aeration is for maintaining the mixture in an aerobic state. As the aeration method, air is sent to the inside of the fermentation tank in which the mixture is stored, exhausted from the inside of the fermentation tank, or inside the fermentation tank. Air supply and exhaust are preferably used. The air flow rate depends on the organic waste to be treated,
Mixture of 1 m ³ to per minute 0.01～2.0M ³
Is preferred. If it is less than 0.01 m ³ per minute, the mixture may not be in a good aerobic state, and if it exceeds 2.0 m ³ per minute, the fermentation temperature of the mixture may be low, which is not preferable.

According to the present invention, a new mixture is not added and mixed during the fermentation process of the first fermentation step, and the mixture is completely treated for a predetermined period of time. After the first fermentation step, the total amount of the mixture is changed. Batch transfer to the second fermentation step. Therefore, the fermentation process time does not shift to the second step of the mixture, which is shorter than the predetermined time, that is, the short pass does not occur, and the quality is stable.

In the second fermentation step of the present invention, the first fermentation step is used.
It is treated for 3 to 10 days in the same manner as the process. In the second fermentation step, the organic substances contained in the organic waste, which are relatively easily decomposed, are decomposed and stabilized by the microorganisms.

The fermentation treatment time required for the second fermentation step varies depending on the organic waste used as a raw material, but it is 3 to 1
0 days. If the treatment time is less than 3 days, decomposition and stabilization of organic substances will be insufficient and the quality of the product will be deteriorated, so that it cannot be used. If the treatment time exceeds 10 days, the product quality is not affected, but the treatment tank volume becomes unnecessarily large and it cannot be used.

The fermentation treatment system used in the second fermentation step is not particularly limited as in the first fermentation step. Also,
As in the first fermentation step, stirring and aeration are preferably performed for the purpose of promoting the progress of the fermentation reaction.

In the present invention, since the mixtures having different treatment times do not mix with each other during the fermentation process of the second fermentation step, the treatment is completely performed for a predetermined time, and after the second fermentation step is completed, The whole amount is batch-transferred to the fermentation third step. Therefore, a transition to the third step of fermentation of the mixture, that is, a short pass does not occur in the mixture in which the fermentation treatment time is shorter than a predetermined time, so that the quality is stable.

The first fermentation step and the second fermentation step in the present invention correspond to the treatment period commonly called the primary fermentation treatment. As described above, the fermenter serving as a reaction field of these steps is not particularly limited, but these steps are performed in a fermenter divided into upper and lower two stages by a partition, that is, a vertical two-stage fermentor. Is especially preferable. The vertical two-stage fermenter has a small installation space because it is a vertical type, and because it is a closed box type, it is possible to suppress the dissipation of fermentation heat to the outside,
The strong odor generated during the fermentation reaction can be collected without leaking to the outside. By introducing the collected odor into the deodorization processing device and performing deodorization processing, the work environment and the environment around the facility can be maintained well.

The third fermentation step in the present invention is so-called secondary fermentation treatment, and in the present invention, the secondary fermentation treatment time is within 30 days. In the third fermentation step, microorganisms decompose the organic substances contained in the organic waste that are relatively difficult to decompose and the organic substances derived from rice husk.

The processing time required for the third fermentation step depends on the type of organic waste used as a raw material. It is necessary to set a long treatment time for organic wastes containing a large amount of fats and oils, which require a relatively long time to decompose, or organic wastes having a high degradable organic matter ratio and requiring a long time for stabilization. On the other hand, in the case of, for example, organic sludge discharged from the wastewater treatment facility that is relatively easily decomposed and stabilized, the third fermentation step may be skipped on day 0, that is, the production step may be performed.

The fermentation treatment method used in the fermentation third step is not particularly limited as in the fermentation first step and the fermentation second step, and in the same manner as the fermentation first step and the fermentation second step, the fermentation reaction It is preferable to carry out stirring and aeration for the purpose of promoting the progress.

The mixture treated in the third fermentation step for a predetermined time is taken out and commercialized. At the time of commercialization, in consideration of the user's request, it is possible to carry out a drying treatment for removing water to a water content which is easy to handle as compost or a granulating treatment by a pelletizer or the like.

The quality of the product produced according to the present invention, namely compost, is comparable to the quality of the product treated for more than 60 days by the conventional fermentation treatment method, and when applied to green farmland,
There is no fear of damaging the growth of plants.

An example of the embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a diagram showing an example of a process of a method for fermenting an organic waste according to the present invention. First, organic waste and rice husks are mixed in the mixing step 1, and then the mixture is transferred to the first fermentation step 2. After completion of fermentation treatment for a predetermined time in the first fermentation step 2, the whole amount of the mixture is fermented in the second step 3
Batch transfer to. After completion of the fermentation treatment for a predetermined time in the second fermentation step 3, the entire amount of the mixture is batch-transferred to the third fermentation step 4. The mixture that has undergone the fermentation treatment for a predetermined time in the third fermentation step 4 is commercialized in the commercialization step 5. Further, at the time of transfer from each fermentation process to the next process or in the commercialization process 5, a part of the mixture can be returned to the mixing process 1 through the return line 6.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 A mixture obtained by mixing dehydrated sludge discharged from a sewage treatment plant, rice husk and fermented material after fermentation treatment was put into the upper stage of a cylindrical vertical two-stage fermenter partitioned into upper and lower stages. According to the method of the present invention, after the upper stage was treated for 6 days (fermentation first step), the whole amount was transferred to the lower stage, and the lower stage was subjected to fermentation treatment for 6 days (fermentation second step). Venting of the upper and lower fermentor outside air was carried out 0.1 m ³ air per minute to a mixture of 1 m ^3. The stirring was performed by rotating the stirring blade horizontally projected on the vertical rotating shaft once for 15 minutes. After completion of the fermentation treatment for a predetermined time, the whole amount of the fermented product was taken out and further treated in a sedimentary fermenter for 30 days (fermentation third step). Venting the deposition type fermenter, outside air was carried out 0.1 m ³ air per minute to a mixture of 1 m ^3. Moreover, it cut back once every 10 days using a shovel.

The fermented product obtained by the fermentation treatment for a total of 42 days was dried to a water content of 35%, and then the ignition loss, p
H, nitrate nitrogen, total nitrogen, BOD and Komatsuna germination index were measured. In addition, these measurement items are the items that determine the quality standard of the sewage sludge compost in "Indicator of sewage sludge compost (Part 2)" (published by Sewage Sludge Resource Utilization Council, 1985). Loss on ignition, pH, nitrate nitrogen,
Total nitrogen and BOD were measured according to the “Sewage Sludge Analysis Method” (issued by the Sewage Sludge Resource Utilization Council, 1996) or the “Fertilizer Analysis Method” (issued by Yokendo, 1988). The Komatsuna germination index was measured by the following method.

Komatsuna germination index measuring method: Dry weight 1 g
20 ml of distilled water was added to the fermented product corresponding to and the extraction treatment was performed at 60 ° C. for 3 hours. After filtering this extract with gauze, 10 ml of the filtrate was poured into a petri dish lined with two filter papers. 50 Komatsuna seeds were sown on the filter paper, covered with a Petri dish, and then cultivated at room temperature without light irradiation. As a control, the same cultivation was performed using distilled water. The germination number of the seeds on the 3rd day of cultivation was measured and evaluated by the relative value (germination index:%) when the value of the control was 100. The measurement results are shown in Table 1.

[0033]

[Table 1]

Example 2 The same mixture as in Example 1 was added to the upper stage of the same vertical two-stage fermentation tank as in Example 1 and treated for 6 days in the upper stage (fermentation according to the method of the present invention). After the first step), the whole amount was transferred to the lower stage, and the fermentation treatment (fermentation second step) was performed for 6 days in the lower stage. Aeration and stirring conditions were the same as in Example 1.
The fermented product obtained by the fermentation treatment for a total of 12 days was dried to a water content of 35%, and then the loss on ignition, pH, nitrate nitrogen, total nitrogen, BOD and komatsuna germination index were measured. The measuring method is the same as that of the first embodiment. Table 1 shows the measurement results
Shown in.

Comparative Example 1 The same mixture as in Example 1 was placed in a silo fermenter in which the mixture was taken out once a day and a new mixture was placed, and a fermentation treatment was carried out for 12 days. . The aeration conditions were the same as in Example 1, and the stirring was performed by rotating the pin mixer at the time of taking out once a day. This method is different from the method of the present invention in that the mixtures having different treatment times are mixed in the fermenter. The mixture taken out was further treated in the same sedimentary fermenter as in Example 1 for 60 days.

After the fermented product obtained by the fermenting process for a total of 72 days was dried to a water content of 35%, the loss on ignition,
pH, nitrate nitrogen, total nitrogen, BOD and komatsuna germination index were measured. The measuring method is the same as that of the first embodiment. The measurement results are shown in Table 1.

Comparative Example 2 The same mixture as in Example 1 was put into the same silo type fermenter as in Comparative Example 1 to carry out fermentation treatment for 12 days. Aeration was performed as in Example 1, and stirring was performed as in Comparative Example 1.
The fermented product obtained by the fermentation treatment for a total of 12 days was dried to a water content of 35%, and then the loss on ignition, pH, nitrate nitrogen, total nitrogen, BOD and komatsuna germination index were measured. The measuring method is the same as that of the first embodiment. Table 1 shows the measurement results
Shown in.

The properties of the fermented product of Example 1 (42 days treated by the method of the present invention) and the fermented product of Example 2 (12 days treated by the method of the present invention) are comparative examples in all items. It was judged that the ripening was sufficient as it was about the same as the fermented product of No. 1 (72-day treatment by a general fermentation method different from the method of the present invention). On the other hand, Comparative Example 2
The properties of the fermented product (treated for 12 days by a general fermentation method different from the method of the present invention) are, in particular, pH, BOD and Komatsuna germination index in Example 1, Example 2 and Comparative Example 1.
It was judged to be inferior to the fermented product of No. 1, and the ripening was insufficient.

[0039]

EFFECTS OF THE INVENTION According to the present invention, it is possible to produce a high-quality compost that does not harm plants when applied to green agricultural land in a shorter fermentation period as compared with conventional methods, that is, has high application safety. It is possible to make fermentation tanks and facilities compact,
Furthermore, the operating cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a process of a fermentation treatment method for organic waste of the present invention.

[Explanation of symbols]

1 mixing process 2 Fermentation first step 3 Second fermentation process 4 Fermentation 3rd process 5 Commercialization process 6 Return line

Claims (4)

[Claims] 1. A method of fermenting a mixture of organic waste and rice husk, which comprises performing a fermentation first step in which the number of days of fermenting treatment is 3 to 10 days, and the total amount of the obtained treated product is the number of days of fermenting treatment. The method for fermentation treatment of organic waste, comprising transferring to a second fermentation step for 3 to 10 days. 2. A method of fermenting a mixture of organic waste and rice husk, which comprises performing a fermentation first step in which the number of days of fermentation treatment is 3 to 10 days, and the total amount of the obtained treated product is determined by the number of days of fermentation treatment. Is transferred to the second fermentation step, which is 3 to 10 days, and the entire amount of the obtained processed product is transferred to the third fermentation step, which has a fermentation processing time of 30 days or less. . 3. The fermentation treatment according to claim 1, wherein the fermentation first step is performed in the upper stage of the fermentation tank divided into upper and lower two stages by the partition, and then the fermentation second step is performed in the lower stage of the fermentation tank. Method. 4. The fermentation treatment method according to claim 1, wherein the organic waste is organic sludge discharged from a wastewater treatment facility.