JP5565773B2 - Compost manufacturing method and apparatus - Google Patents

Description

  The present invention relates to a compost manufacturing method and apparatus.

Composting is a technique for producing organic fertilizers by decomposing and stabilizing livestock excreta and the like by the action of aerobic microorganisms. However, the compost production process generates powerful greenhouse gases such as dinitrogen monoxide (N ₂ O) and 23 times more methane (CH ₄ ), which have 296 times the greenhouse effect compared to carbon dioxide (CO ₂ ). doing.

Non-patent document 1 describes that Japan's agricultural greenhouse gas emissions are about 3% of total emissions, of which CH ₄ and N ₂ O derived from livestock are CH generated from the gastrointestinal tract during livestock breeding. ₄ and CH ₄ and N ₂ O generated from the handling of waste. Emissions of 709,000 tons of carbon dioxide (CO ₂ eq) are calculated mainly for ruminant livestock (cattle, sheep, goats, etc.), and 7261 thousand tons of CO ₂ eq of greenhouse gas emissions from livestock waste management. Non-patent document 1 describes the characteristics of greenhouse gas generation originating from livestock excreta treatment, the main livestock excreta treatment in Japan, the concentration of greenhouse gases (CH ₄ , N ₂ O) by gas chromatography and Fourier transform infrared spectroscopy. It explains the measurement method, the grasp of the generation coefficient of each treatment system of livestock excrement, and the evaluation of greenhouse gas generation from sedimentary composting treatment facility, forced ventilation composting treatment facility, sewage purification treatment facility and slurry storage.

Patent Document 1 discloses a method for suppressing N ₂ O generation in composting. In this method, after dewatering sludge with an electroosmotic dehydrator, when producing compost by fermenting sludge in a fermenter, in addition to the lower air supply part provided at the lower part, the upper air supply part provided at the upper part is used. Blowing is performed to suppress N ₂ O production.

JP 2010-208932 A

Bunseki: No.2, Page.79-83 (2010.02.05)

  Beginning with the forced ventilation type composting treatment facility introduced in Non-Patent Document 1, in general composting facilities, air is sent from the bottom of the compost from the blower to activate aerobic microorganisms in the compost. It activates microorganisms and promotes composting. However, about 90% of the running cost of composting facilities is the electricity charge of the blower, and the monthly charge per blower is about 20,000 to 30,000 yen. Usually, composting facilities use several blowers, which increases the weight of electricity bills.

  In the method described in Patent Document 1, when producing compost by fermenting sludge in a fermenter, air is also blown from the upper air supply unit provided at the top, and the amount of air supplied is increased to suppress N2O production. It is. However, air is also supplied from the lower air supply unit provided in the lower part, and air is blown from the upper air supply unit in addition thereto, and it is difficult to reduce the energy cost for supplying air.

Although CH ₄ and N ₂ O are greenhouse gases and their reduction is desired, the actual situation is that no concrete and effective proposal has been made so far.

Accordingly, the present invention can reduce the power cost of the blower, and an object of the invention to provide a new composting techniques can also be reduced emissions of CH ₄ and N ₂ O.

The present invention is as follows.
[1]
A method for producing compost comprising aeration of compost material,
The aeration is performed according to the aeration amount with respect to the unit amount of the compost material determined according to the temperature of the compost material, and the temperature of the compost material is measured continuously or intermittently, and based on the obtained measurement temperature The said manufacturing method which determines the ventilation | gas_flowing amount with respect to the unit amount of compost material continuously or intermittently.
[2]
The manufacturing method according to [1], wherein the aeration amount with respect to the unit amount of compost material is calculated as a product of coefficients determined in advance according to the dry weight and temperature of the compost material.
[3]
The coefficient determined according to the temperature is a function of the temperature in the temperature range of 70 ° C or lower and while the temperature is rising, and is a constant at a temperature exceeding 70 ° C, and the temperature range of 70 ° C or lower And the production method according to [1] or [2], wherein the constant is constant while the temperature is lowered.
[Four]
The manufacturing method according to any one of [1] to [3], wherein the temperature of the compost material is measured in the vicinity of the central portion of the compost material being ventilated.
[Five]
The manufacturing method according to any one of [1] to [4], wherein the compost material has a moisture content of 40 to 80%.
[6]
The manufacturing method according to any one of [1] to [5], wherein aeration of the compost material is performed so that air is uniformly supplied to the compost material.
[7]
The manufacturing method according to any one of [1] to [6], wherein aeration with respect to the compost material is performed while turning back at predetermined intervals.
[8]
Compost material fermenter,
Aeration means to compost material provided in the fermenter,
A thermometer for measuring the temperature of the compost material, and means for determining the air volume of the aeration device based on the temperature measured by the thermometer,
A compost manufacturing apparatus comprising: means for controlling the air volume of the ventilation means with the air volume determined by the air volume determining means.
[9]
The manufacturing apparatus according to [8], wherein the air volume determining means and the air volume control means are inverter control devices, and the inverter control device controls the ventilation means via the inverter.

  According to the present invention, the amount of air blown to the compost material is controlled to an appropriate amount of air blown according to the fermentation status of the compost material, thereby reducing wasteful ventilation and reducing power costs, and in addition, compost By sending an appropriate amount of ventilation according to the fermentation status, greenhouse gas emissions can be suppressed.

The temperature transition, oxygen consumption and supply rate in general forced-air composting (composting using a blower) are shown. An example of the temperature change of the compost material in the compost manufacturing method of this invention is shown. The temperature change of the composting period in the compost manufacturing method of an Example is shown. The simulation value of the ventilation | gas_flowing amount output with the inverter control apparatus and the inverter from the ventilation | gas_flowing amount information of the coefficient A in the compost manufacturing method of an Example is shown. The time-dependent change of the integrated power consumption of a fan in the compost manufacturing method of an Example is shown. In composting process of Example illustrates the time course of dinitrogen monoxide (N ₂ O). In composting process of Example illustrates the time course of methane (CH _4). An example of the compost manufacturing apparatus of this invention is shown.

<Compost production method>
The present invention relates to a method for producing compost comprising aeration of compost material. In the production method of the present invention, the aeration is performed with the aeration amount for the unit amount of the compost material determined according to the temperature of the compost material. Further, the temperature of the compost material is measured continuously or intermittently, and the ventilation rate for the unit amount of compost material is determined continuously or intermittently based on the obtained measurement temperature.

  In the method for producing compost of the present invention, the air flow rate for the compost material is determined as the air flow rate for the unit amount of the compost material according to the temperature of the compost material. Specifically, the ventilation amount f for the unit amount of compost material is calculated as a value obtained by dividing the product of the coefficient A determined in advance according to the dry weight Ws of compost material and the temperature by the volume V of the compost material.

  In general forced-air composting (composting using a blower), the temperature transition and oxygen consumption / supply rate as shown in FIG. 1 are shown. Composting is a biodegradation reaction by aerobic microorganisms, and its temperature conditions and required air volume (oxygen volume) always change. Normally, a large amount of air (oxygen) is consumed when the compost temperature rises, and after the temperature rises above 60 ° C, the amount of air (oxygen) used in composting starts to decrease, 70 ° C If it exceeds, the required amount of air (oxygen amount) is significantly reduced. However, in an actual compost house, the amount of air supplied by the blower (oxygen amount) is normally constantly sending an excessively large ventilation amount so as not to run out of oxygen.

  In the present invention, the temperature of the compost material is measured continuously or intermittently, and the ventilation rate for the unit amount of compost material is determined continuously or intermittently based on the obtained measurement temperature. At that time, a predetermined coefficient A is used according to the temperature. The coefficient A is a coefficient that can be obtained experimentally, and is a coefficient that varies depending on the temperature (which is a function of temperature) but is substantially determined regardless of the type of compost material.

  More specifically, the coefficient A determined in advance according to the temperature is a function of temperature in a temperature range of 70 ° C. or lower and while the temperature is rising. Further, it is a constant at a temperature exceeding 70 ° C., and is a constant in a temperature range of 70 ° C. or lower and while the temperature is decreasing. The coefficient A is a constant even in a temperature range of 20 ° C. or lower. As the coefficient A determined in advance according to the temperature, for example, the functions and constants shown in Table 1 below can be used. This function calculates the change in oxygen consumption by microorganisms observed during the composting process by applying the least squares method from multiple measurement results for each moisture content in the temperature range shown in Table 1. Is done. However, the functions and constants shown in Table 1 are examples, and can be determined experimentally and appropriately set according to the structure of the compost manufacturing apparatus, particularly the structure and capacity of the blower.

  The dry weight Ws of the compost material is the wet weight W and the moisture content M.I. W. It is obtained as a value multiplied by (%). The volume V of the compost material is the total volume of the compost material used as a raw material for composting.

  The temperature of the compost material can be measured near the center of the aerated compost material. Alternatively, the temperature of the compost material may be measured at a location where the temperature is detected relatively high near the top of the compost in the case of pressure-venting aeration composting, and near the suction port on the bottom of the compost in the case of suction aeration. it can. In addition, when the total volume of the compost material is large, the temperature of the compost material is measured at a plurality of locations in the horizontal and / or vertical directions, and the measured temperatures at the plurality of locations are calculated by, for example, calculating the coefficient A from the average value. It can also be determined.

  There are no particular restrictions on the compost material. , A material containing auxiliary materials such as rice straw, or a material obtained by mixing them. Further, the compost material can have a moisture content of about 40% to 80%, but is preferably about 50 to 70%. Generally, in order for fermentation to proceed well, it is appropriate that the compost material has a moisture content of about 50 to 70%. Therefore, even in the present invention, the compost material has a moisture content of about 50 to 70%. Is appropriate. The upper limit of the moisture content of the compost material is not particularly limited, but is, for example, 80% or less.

  Aeration of the compost material is performed so that air is uniformly supplied to the compost material. By uniformly supplying air to the compost material, fermentation in the compost material also proceeds uniformly, the temperature distribution of the compost material becomes relatively uniform, and control becomes easy. For the uniform supply of air to the compost material, for example, a method of composting while dividing the compost material into comparatively small sections and continuously moving the compost material can be employed. Alternatively, the air can be uniformly supplied to the compost material by composting with a composting apparatus provided with a plurality of air supplies.

  The compost material can be turned back at a predetermined interval. Cut-back is also called top-and-bottom turning, and is an operation such as mixing composting materials being fermented or adding a part of new composting materials. The temperature of the compost material generally rises to 70 ° C or higher as the fermentation progresses, and generally decreases after maintaining the temperature of 70 ° C or higher for a certain period. Switching is preferably performed when the temperature of the compost material shows a downward trend, for example, in the range of 30 to 60 ° C. The downward trend indicates that the fermentation is losing momentum. By performing the turn-back at that timing, the fermentation can be activated again and composting can be promoted. Since the temperature of the compost material starts to rise after switching, the coefficient at the time of temperature rise is used as the coefficient A. An example of temperature change of compost material is shown in Fig.2.

  The composting material is ventilated to allow composting to proceed, and if the temperature does not rise to a high temperature even after turning over, composting is terminated. The compost produced by the method of the present invention can be used, for example, as an organic fertilizer, a soil conditioner, a moisture conditioner, a livestock litter, a deodorizing material, a biofuel, and the like.

<Compost production equipment>
The present invention includes a compost production apparatus. The compost production apparatus of the present invention includes a compost material fermenter, a vent means for compost material provided in the fermenter, a thermometer for measuring the temperature of the compost material, and aeration based on the temperature measured by the thermometer. Means for determining the air volume of the apparatus, and means for controlling the air volume of the ventilation means with the air volume determined by the air volume determining means. An example of the compost production apparatus of the present invention is shown in FIG.

  The compost material fermenter may be a fermenter composed of a single room or a fermenter composed of a plurality of rooms (sections). The fermenter is provided with a ventilation means for the compost material. The ventilation means to the compost material can include, for example, a blower and a vent pipe connected to the blower. A single or a plurality of aeration tubes can be provided in the lower part of the fermenter. It is preferable that the ventilation pipe has a structure capable of uniformly ventilating the entire compost material. For example, such a structure is obtained by processing a plurality of holes in a straight pipe made of vinyl chloride, and forming a single or a plurality of pipes. It is a structure in which a single or a plurality of effective pipes such as an installed structure or a corrugated pipe are installed. Existing fermenters and aeration means can be used as they are.

  The thermometer for measuring the temperature of the compost material may be any one that can transmit the measured temperature to the means for determining the air volume of the ventilator by means of an electrical signal. For example, a thermocouple, a resistance temperature detector, infrared radiation, etc. A thermometer etc. can be mentioned. An electrical signal converter or the like can be used for the electrical signal conversion. A plurality of thermometers can be provided. The thermometer may be fixed or movable so that it can be installed at a predetermined position of the compost material.

The air volume determining means and the air volume control means can be, for example, an inverter control device, and the inverter control device can control the ventilation means via the inverter. In this case, the voltage output to the blower included in the ventilation means based on the temperature measured by the thermometer is performed by the inverter control device and the inverter. The electrical signal of the temperature measured by the thermometer is input to the input / output terminal block of the inverter control device. In accordance with the input value, an electric signal is output from the inverter control device to the inverter so as to vary the frequency to an appropriate value for the inverter. By determining the frequency output from the inverter, power corresponding to the frequency is output from the inverter to the blower. By this series of operations, it is possible to supply an appropriate amount of air to the compost material according to the fermentation status of the compost. In the inverter control device, the dry weight Ws of the compost material, the coefficient A, and the volume V of the compost material are input in advance to determine the air volume, and the ventilation amount f is calculated based on the temperature electrical signal. Further, the frequency corresponding to the air flow f can be determined from the specifications and characteristics of the blower. By inputting output signal values giving these frequencies to the inverter control device, it is possible to determine the air volume based on the temperature measured by the thermometer. The output voltage value from the inverter control device to the inverter is input to the control circuit terminal block of the inverter in a stepped manner, and the power corresponding to the input value is output from the main circuit terminal block to the ventilation device in a stepped manner. . By using these inverter control devices and inverters, it becomes possible to control the ventilator, always supply air to the compost material with the optimum air flow, and suppress electricity consumption, as well as CH ₄ and N ₂ O emissions can also be reduced.

  The present invention will be further described below based on examples. However, these examples are illustrative and do not limit the scope of the present invention.

The following composting experiment was conducted using the compost manufacturing apparatus of the present invention shown in FIG. About 40 cubic meters of a mixture of dairy cow dung and wheat straw was put into a fermenter having a volume of about 53 cubic meters per tank, and composting was carried out by pumping aeration from the bottom of the compost material. The initial moisture content of the input compost material was about 80%, and the test period was conducted in an extremely difficult composting environment in the winter period from February to March. Composting was based on the conventional method with one introducing this compost production system and the other with constant air flow, and composting was performed at the same time. During the composting period, the compost temperature is measured with a temperature meter, the energy consumption of the blower is measured with an energy monitor, and the greenhouse gases nitrous oxide (N ₂ O) and methane (N ₂ O) and methane ( CH ₄₎ were measured.

  Figure 3 shows the temperature change during the composting period. As for the temperature change during the composting period, in the test zone where the present compost production system is introduced, the temperature rises faster and the temperature is maintained higher than the conventional practice zone. This means that composting is promoted by the introduction of this compost production system.

  FIG. 4 shows a simulation value of the air flow output from the inverter control device and the inverter from the air flow information of the coefficient A. In this embodiment, the output is stepped in order to prevent the inverter from tripping. In the customary zone, a constant air flow rate is applied as in the conventional method, but in the zone where the compost production system is introduced, the air flow rate fluctuates. This is because the coefficient A is calculated according to the fermentation status, and the blower is controlled by the inverter control device and the inverter based on the aeration amount information. In addition, from the demonstration test of this compost production system, the following three results have been obtained for energy saving and reduction of greenhouse gas emissions.

The first point is to reduce the power consumption of the blower. As shown in FIG. 5, when this compost production system was also introduced, it was possible to reduce the power consumption to a maximum of about 90% compared to the conventional practice zone. This also means that carbon dioxide (CO ₂ ) emissions associated with power production can be reduced by up to about 90%.

The second point is reduction of nitrous oxide (N ₂ O), a greenhouse gas. As shown in FIG. 6, in the compost production system introduction zone, the total emission of N ₂ O during the composting period could be reduced by about 50% compared to the conventional district.

The third point is the reduction of methane (CH ₄ ), a greenhouse gas. As shown in FIG. 7, in the compost production system introduction district, the total CH ₄ emissions during the composting period could be reduced by about 80% compared to the customary district.

From the results of the above three points, it can be seen that the compost production technology of the present invention can save energy and reduce CO ₂ emissions accompanying power consumption. In addition, we can see that N ₂ O and CH ₄ , which are extremely powerful greenhouse gases, can be reduced.

  INDUSTRIAL APPLICABILITY The present invention is a compost production technique that can satisfy both energy saving and greenhouse gas emission suppression at the same time, and is useful in various fields related to compost production.

Claims (6)

A method for producing compost comprising aeration of compost material,
The aeration is performed according to the aeration amount with respect to the unit amount of the compost material determined according to the temperature of the compost material, and the temperature of the compost material is measured continuously or intermittently, and based on the obtained measurement temperature Continuously or intermittently determine the ventilation rate for a unit amount of compost material,
However, the ventilation rate for the compost material of the unit amount is calculated as a product of a coefficient predetermined according to the dry weight and temperature of the compost material, and the coefficient predetermined according to the temperature is a temperature range of 70 ° C. or less. And while the temperature is rising, it is a function of temperature, constant at temperatures above 70 ° C., constant in the temperature range below 70 ° C. and while the temperature is falling, and
Including turning compost material when the measured temperature shows a downward trend ,
The manufacturing method. 2. The production method according to claim 1 , wherein the temperature of the compost material is measured in the vicinity of the center of the compost material being ventilated. The production method according to claim 1 or 2 , wherein the compost material has a moisture content of 40 to 80%. The manufacturing method according to any one of claims 1 to 3 , wherein aeration of the compost material is performed so that air is uniformly supplied to the compost material. Compost material fermenter,
Aeration means to compost material provided in the fermenter,
A thermometer for measuring the temperature of the compost material, and means for determining the air volume of the aeration device based on the temperature measured by the thermometer,
Means for controlling the air volume of the ventilation means with the air volume determined by the air volume determining means,
The air volume determining means and the air volume control means are inverter control devices, and the inverter control device controls the ventilation means via the inverter.
The compost manufacturing apparatus used for the method in any one of Claims 1-4 . The aeration means is controlled by the inverter control device so as to realize a ventilation amount for a unit amount of compost material calculated as a product of a predetermined coefficient according to a dry weight and a temperature of the compost material. 5. The manufacturing apparatus according to 5 .