JP7495587B1 - Compost production method, control device used therein, compost production system, compost production program, and recording medium - Google Patents

Abstract

[Problem] To provide a compost production method that can appropriately adjust aeration according to the composting conditions and circumstances and can efficiently respond to changes in compost information, and a control device, compost production system, and compost production program and recording medium used therein. [Solution] A compost production method that at least controls aeration of compost material so that the compost material reaches a predetermined temperature or higher (preferably 60°C or higher) in the production of compost, and includes a change amount acquisition step of determining the amount of change in environmental information, which is information regarding the temperature and/or oxygen concentration of the compost material, and an aeration control step of controlling the aeration of the compost material based on the amount of change in the environmental information. [Selected Figure] Figure 3

Description

The present invention relates to a compost production technology that at least controls the aeration of compost materials during compost production.

In composting, which involves decomposing and fermenting organic waste such as livestock waste using aerobic microorganisms to create organic fertilizer, it is necessary to create appropriate environmental conditions that make it easy for the aerobic microorganisms to be active. Environmental conditions include various items such as nutrient sources, air (oxygen), moisture, and temperature, of which air (oxygen) is one of the essential items for composting. Aerobic microorganisms use air to carry out oxidative decomposition, which breaks down the organic waste that is the compost material, generating fermentation heat through the oxidation reaction and promoting the evaporation of moisture in the compost material.

Methods for supplying air to compost materials include turning over the fermenting compost so that it comes into uniform contact with air by stirring and mixing it, as well as a method of blowing air (aeration) through the compost material using a blower or the like (hereinafter referred to as the "aeration method").
Composting is a decomposition reaction caused by aerobic microorganisms, and the amount of air (oxygen) required varies depending on the type of compost material and the fermentation stage of the compost. Therefore, in order to perform proper composting using the aeration method, it is necessary to adjust the amount of air supplied (aeration rate) according to the composting conditions and circumstances.
For example, in the early stages of composting, the activity of all aerobic microorganisms becomes active, so a large amount of aeration is required, whereas in the later stages, the activity of all aerobic microorganisms becomes subdued, so less aeration is required. Also, when aeration is performed using a blower, the increase in power consumption required to operate the blower can be suppressed by appropriately adjusting the amount of aeration.

As a method for adjusting the amount of aeration in the aeration method, a method has been proposed in which the amount of aeration is adjusted based on the temperature of the compost material (hereinafter sometimes referred to as "compost temperature"). Since fermentation heat is generated by the decomposition reaction by aerobic microorganisms, the compost temperature changes depending on the level of fermentation (the activity level of the aerobic microorganisms as a whole). And since the amount of aeration required changes depending on the level of fermentation, it is possible to appropriately adjust the amount of aeration by basing it on the compost temperature.

For example, Patent Document 1 proposes an aeration control method and device for a composting apparatus that uses a forced-air fermentation tank to compost municipal waste and other organic materials, and controls the amount of aeration based on the temperature of the raw material and the amount of temperature change per unit time.
The ventilation rate is controlled by using the temperature pattern change and the amount of change as parameters so that more ventilation is supplied to the high temperature area than to the low temperature area in the temperature distribution in the fermentation tank, and the ventilation rate is increased when the fermentation rate is fast and decreased when the fermentation rate is slow. By performing such control, the fermentation can be made uniform, power consumption can be reduced, and fluctuations in the fermentation rate can be easily followed.

Patent Document 2 proposes a compost production method and apparatus for aerating compost material, in which the aeration is performed at an aeration rate determined based on the temperature of the compost material measured continuously or intermittently.
The specific aeration rate is calculated as the product of the dry weight of the compost material and a coefficient A, which is determined in advance according to the temperature, divided by the volume of the compost material. This coefficient A is an experimentally determined coefficient, which is a function of temperature in the temperature range below 70°C and while the temperature is rising, and is a constant at temperatures above 70°C, a constant in the temperature range below 70°C and while the temperature is falling, and is also a constant in the temperature range below 20°C. By calculating the aeration rate in this way, it is said that the aeration rate can be controlled to an appropriate level according to the fermentation status of the compost material.

Japanese Patent Application Laid-Open No. 62-167278 Patent No. 5565773

The required amount of aeration varies depending on the type and amount of compost material, the pile condition of the compost, etc. (hereinafter, these are collectively referred to as "compost information"), so when adjusting the amount of aeration based on the compost temperature, the setting conditions for adjustment must be changed according to the compost information. The setting conditions are usually determined experimentally with the compost information fixed, so if there are many parameters that make up the setting conditions, changing the setting conditions takes a lot of work.

In the ventilation control method and device proposed in Patent Document 1, the ventilation rate is controlled using the compost temperature and its change as parameters, so if the compost information changes, it may be necessary to change the setting conditions for the two parameters, compost temperature and its change. In the compost production method and device proposed in Patent Document 2, multiple temperature ranges are set and a coefficient A is set for each temperature range, so if the compost information changes, it may be necessary to change both the temperature range setting and the coefficient A setting.

The present invention was made in light of the above-mentioned circumstances, and the object of the present invention is to provide a compost production method that can appropriately adjust ventilation according to the composting conditions and circumstances, and that can efficiently respond to changes in compost information, as well as a control device, a compost production system, a compost production program, and a recording medium used therein.

As a result of extensive research into solving the above problems, the inventors discovered that the following invention meets the above objectives, and thus arrived at the present invention.

That is, the present invention relates to the following inventions.
<1> A method for producing compost, comprising at least controlling aeration of a compost material so that the compost material is at or above a predetermined temperature,
a change amount acquisition step of determining a change amount of environmental information, which is information regarding the temperature and/or oxygen concentration of the compost material;
and an aeration control step of controlling aeration of the compost material based on the amount of change in the environmental information.
<2> The temperature of the compost material is used as the environmental information,
The compost producing method according to <1>, wherein the change amount acquisition step determines the amount of change in temperature.
<3> In the ventilation control step,
increasing aeration of the compost material if the change in temperature is equal to or greater than a first threshold;
The compost producing method according to <2>, wherein the amount of ventilation is reduced when the amount of change in temperature is equal to or less than a second threshold value.
<4> The compost producing method according to <3>, wherein the first threshold value and the second threshold value are determined based on at least a state of the compost material.
<5> The method for producing compost described in any one of <1> to <4>, wherein aeration is controlled so that the temperature of the compost material is 60°C or higher.
<6> The method for producing compost according to any one of <1> to <5>, wherein the compost material is cow dung and/or swine feces.
<7> A control device used in the compost production method according to any one of <1> to <6>,
A control device comprising: an amount of change acquisition unit that executes the amount of change acquisition step; and an airflow control unit that executes the airflow control step.
<8> A compost production system including the control device according to <7>,
The compost production system further comprises a fermentation facility having a storage section for storing the compost material and fermenting it, a sensor device for detecting the environmental information, and an aeration device for aerating the compost material based on information output from the control device.

<9> A compost production program for at least controlling aeration of a compost material so that the compost material reaches a predetermined temperature or higher in the production of compost,
On the computer,
a change amount acquisition step of determining a change amount of environmental information, which is information regarding the temperature and/or oxygen concentration of the compost material;
and an aeration control step of controlling aeration of the compost material based on the amount of change in the environmental information.
<10> A computer-readable recording medium having the compost production program according to <9> recorded thereon.

The compost production method and the control device, compost production system, compost production program, and recording medium used therein of the present invention control ventilation based only on the amount of change in environmental information, making it possible to appropriately adjust ventilation according to the composting conditions and circumstances, and efficiently respond to changes in compost information.

1 is a block diagram showing an example of the configuration of a compost production system according to the present invention. FIG. 2 is a front view showing an example of a storage section. FIG. 2 is a block diagram showing a configuration example of a control device. FIG. 1 is a diagram showing a configuration example of a ventilation device. FIG. 4 is an enlarged bottom view of the end of the ventilation pipe. 13 is a diagram showing an example of a state in which a ventilation pipe is fitted into a groove. FIG. 4 is a flowchart showing an example of the operation of the compost producing system according to the present invention. 1 is a graph showing an example of changes in compost temperature etc. over time. 1 is a graph showing an example of changes over time in compost temperature, oxygen concentration, etc. 1 is a graph showing an example of the change in moisture content in compost material over time. 1 is a graph showing an example of the change over time in organic matter decomposition rate.

The present invention relates to a compost production method that at least controls the aeration of the compost material so that the compost material reaches a predetermined temperature or higher during compost production, and the compost production method includes a change amount acquisition step of determining the amount of change in environmental information, which is information about the temperature and/or oxygen concentration of the compost material, and an aeration control step of controlling the aeration of the compost material based on the amount of change in the environmental information (hereinafter, sometimes referred to as the "compost production method of the present invention").

In the present invention, in composting using an aeration method in which air is sent (ventilated) to compost material, when air is supplied to the compost material, aeration control (hereinafter referred to as "change amount aeration control") is performed based on the amount of change (e.g., the amount of change per specified time) in information (environmental information) about the surrounding environment including the compost material.

The environmental information is information relating to the temperature of the compost materials and the oxygen concentration of the compost materials. For example, the compost temperature is used as the environmental information, and if the compost temperature rises above a predetermined level, the aeration rate is increased, and if the compost temperature falls below a predetermined level, the aeration rate is decreased. By controlling the aeration rate in this way based on the amount of change in the compost temperature, the aeration rate can be appropriately adjusted according to the composting situation.

That is, in the early stages of composting, aerobic microorganisms become more active, so a large amount of aeration (oxygen) is required, but the increased activity of aerobic microorganisms causes the compost temperature to rise, so the amount of aeration can be increased accordingly. On the other hand, in the later stages of composting, aerobic microorganisms become less active, so less aeration is required, but the decreased activity of aerobic microorganisms causes the compost temperature to fall, so the amount of aeration can be reduced accordingly.

In addition, the variable aeration control described above prevents fermentation inhibition caused by excessive aeration when the outside temperature is low, maintains high-temperature fermentation, and produces high-quality compost.

In the compost production method of the present invention, high-temperature fermentation, in which the compost temperature is maintained at a high temperature (preferably 60°C or higher), has the advantages of suppressing the germination of weed seeds in the compost, improving the quality of the compost by preventing damage from pathogens, and promoting the activity of aerobic microorganisms. The compost temperature suitable for high-temperature fermentation is preferably 60°C or higher. However, since the activity of aerobic microorganisms may decrease if the temperature is too high, the compost temperature is preferably 100°C or lower, and more preferably 90°C or lower.

High-temperature fermentation is difficult to maintain, especially in winter when the outside temperature is low, and excessive aeration, for example when aeration is performed at a high rate to ensure the required amount of aeration when the aeration rate is not adjusted and is kept constant, cools the compost material and makes it even more difficult to maintain.
However, according to the compost production method of the present invention, the amount of aeration decreases as the compost temperature decreases, thereby suppressing excessive aeration and preventing the resulting inhibition of fermentation, thereby making it possible to maintain high-temperature fermentation.

The present invention may be realized as a control device that performs the above-mentioned change amount ventilation control, or may be realized as a compost production system that includes, in addition to the control device, a sensor device for detecting environmental information such as compost temperature.
That is, the control device of the present invention is a control device for use in the compost production method of the present invention, and includes a change amount acquisition unit that executes the change amount acquisition step and an aeration control unit that executes the aeration control step. The compost production system of the present invention includes the above-mentioned control device, fermentation equipment including a storage unit that stores compost material and performs fermentation, a sensor device that detects environmental information, and an aeration device that aerates the compost material based on information output from the control device.

The present invention also relates to a compost production program (hereinafter sometimes referred to as the "compost production method of the present invention") that at least controls the aeration of compost material so that the compost material reaches a predetermined temperature or higher (preferably 60°C or higher) in the production of compost, and causes a computer to execute a change amount acquisition step of determining the amount of change in environmental information, which is information regarding the temperature and/or oxygen concentration of the compost material, and an aeration control step of controlling the aeration of the compost material based on the amount of change in the environmental information. The present invention also relates to a computer-readable recording medium having the compost production program of the present invention recorded thereon.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In each drawing, the same components are given the same reference numerals, and the description may be omitted. Also, the configurations in the following description are examples, and the present invention is not limited to these. Furthermore, the following description focuses on the main configurations and operations for implementing the present invention, and the description of general-purpose processing required for implementing the present invention, such as data transmission and reception processing, is simplified or omitted.

FIG. 1 shows an example of the configuration of a compost production system equipped with a control device according to the present invention.
The compost production system 1 of this embodiment targets livestock waste from cows, pigs, etc., and composts by using compost temperature as environmental information and implementing change-rate aeration control to adjust the amount of aeration based on the amount of change in the compost temperature. The compost production system 1 includes a fermentation facility 10 that stores compost material made from livestock waste and ferments the compost material with aerobic microorganisms, a sensor device 20 that detects the temperature of the compost material stored in the fermentation facility 10 (compost temperature), a control device 30 that controls the amount of aeration for the compost material, and an aeration device 40 that aerates the compost material.

The sensor device 20 is connected to the fermentation equipment 10 by being inserted into the compost material in the fermentation equipment 10. The sensor device 20 and the control device 30 are connected by a communication cable 51, and the control device 30 and the aeration device 40 are connected by a communication cable 52, and data is transmitted and received by wired communication.

The aeration device 40 is provided with an aeration pipe 44 that is installed inside the fermentation equipment 10 and supplies air to the compost material, and an inlet pipe 43 that sends air into the aeration pipe 44, and is connected to the fermentation equipment 10 via the inlet pipe 43 and the aeration pipe 44. The sensor device 20 and the control device 30, and/or the control device 30 and the aeration device 40 may transmit and receive data via wireless communication. In this case, a communication cable is not required.

The fermentation equipment 10 is configured as a compost building and has multiple storage sections 11 for storing compost material.

2 is a front view of the storage unit 11. In this embodiment, the fermentation equipment 10 includes two storage units 11a and 11b (hereinafter, the storage units 11a and 11b may be referred to as "storage unit 11" without distinction).
The storage section 11 has a structure in which both sides and the back are surrounded by concrete walls, and the front and top are open. Storage sections 11a and 11b are approximately 300 cm wide (length in the left-right direction in FIG. 2) and approximately 270 cm deep, and the height of the concrete wall separating storage sections 11a and 11b (length in the up-down direction in FIG. 2) is approximately 200 cm. Compost material is piled up in this storage section 11 to a height of approximately 150 cm. A roof (not shown) is provided above storage section 11 to protect it from rain and snow.
The number of storage sections is not limited to two, and the fermentation equipment 10 may be provided with any other number of storage sections, and the size of the storage sections is not limited to the above.

A groove 12 is provided on the bottom surface of the storage section 11 for fitting the ventilation pipe 44 extending from the ventilation device 40. The depth of the groove 12 is set so that the ventilation pipe 44 can be completely fitted into the groove 12 without protruding, for example, the depth is 11 to 12 cm. The width of the groove 12 is also set according to the size of the ventilation pipe 44, for example, 11 to 12 cm. The groove 12 has an open upper surface so that the ventilation pipe 44 can be fitted from above, and the shape of the lower surface may be a flat surface or a concave curved surface.
The depth and/or width of the groove 12 may be greater than 11-12 cm, but is preferably large enough to allow the ventilation pipe 44 to be easily fitted therein and to allow air discharged from the ventilation pipe 44 to be adequately supplied to the compost material.

The grooves 12 are formed from the back surface of the storage section 11 in parallel to the side surface, with a length (approximately 270 cm) that is approximately the same as the depth of the storage section 11. Four grooves 12a, 12b, 12c, and 12d are formed at intervals of approximately 50 cm on the bottom surface of each of the storage sections 11a and 11b (hereinafter, grooves 12a to 12d may be referred to as "groove 12" without distinction). A hole is drilled in the back surface of the storage section 11 that contacts the groove 12, for inserting the feed pipe 43. Note that the number of grooves 12 is not limited to four, and other numbers of grooves may be provided, and grooves may be provided parallel to the back surface instead of the side surface.

In addition to the aeration method using the aeration device 40, air may also be supplied to the compost material stored in the fermentation equipment 10 by turning over, if necessary. Turning over is performed by breaking down the fermenting compost material, stirring it, and redepositing it. By turning over, the compost material located at the surface of the piled up material moves inside, and at the same time, air moves in, so that the entire piled up compost material can come into uniform contact with air.

Turning may be performed when the compost temperature has risen and then dropped, or at a specified interval. In this embodiment, turning is performed at one-week intervals. The fermentation equipment 10 may be equipped with a turning means such as a compost turning machine, and turning may be performed using this. Note that turning may not be required in cases where proper composting is possible without turning.

The sensor device 20 detects the compost temperature and outputs a compost temperature (signal) Tc. The sensor device 20 includes a temperature sensor, and uses a sheathed thermocouple as the temperature sensor.
A thermocouple is a temperature sensor that is made up of two different metal conductors and uses the Seebeck effect to measure temperature, and a sheathed thermocouple is processed by filling and sealing powdered inorganic insulation between the metal covering and the pair of thermocouple wires to insulate the thermocouple wires from the outside air. The thermocouple wires are sealed in a thin tube of a specified length (e.g. 30 cm), and the compost temperature is measured by inserting the tube into the compost material.

The sensor device 20 may be equipped with multiple temperature sensors, and the average value of the compost temperatures detected by each temperature sensor may be output as the compost temperature Tc. A bimetal thermometer or the like may be used as the temperature sensor instead of a sheathed thermocouple. A bimetal thermometer is a thermometer that measures temperature using the properties of a bimetal, which is made by bonding two metal plates with different thermal expansion coefficients together. Since bimetals have the property of changing the way they bend with temperature changes, this property is used to measure temperature.

The temperature sensor of the sensor device 20 is inserted horizontally into the piled compost material at a predetermined height (e.g., 30 cm) from the bottom surface of the storage section 11. Note that the temperature sensor may also be inserted vertically instead of horizontally.

The sensor device 20 measures the compost temperature at a predetermined time interval (hereinafter referred to as the "measurement interval") and outputs the compost temperature Tc. The compost temperature Tc is input to the control device 30 via a communication cable 51 that connects the sensor device 20 and the control device 30. Note that the sensor device 20 may output the compost temperature Tc at other times, for example, in response to a request (signal) from the control device 30, rather than at the measurement interval.

The control device 30 inputs the compost temperature Tc output from the sensor device 20 and performs change-rate aeration control, which controls the amount of aeration for the compost material stored in the fermentation equipment 10 based on the amount of change in the compost temperature.

The control device 30 is configured as a PLC (Programmable Logic Controller) and is equipped with input means, output means, calculation means, storage means, etc. that are included in a normal PLC. A PLC is a control device that controls devices and equipment, etc., and performs sequence control (control in which each control stage proceeds sequentially according to a predetermined order or procedure) using a program. The control device 30 uses a program created using a ladder method (ladder program).

The programs used by the control device 30 may be programs created in a method or programming language other than the ladder method, the control device 30 may be configured with a general-purpose computer other than a PLC, and some or all of the control by the control device 30 may be realized by hardware.

An example of the configuration of the control device 30 is shown in Fig. 3. Fig. 3 shows components that are mainly realized by a program.
The control device 30 includes a change amount acquisition unit 31 and a ventilation control unit 32 .

The change amount acquisition unit 31 inputs the compost temperature Tc output from the sensor device 20, calculates the amount of change in the compost temperature, and outputs the amount of temperature change (signal) dTc. The difference in the compost temperature Tc over a predetermined time interval (hereinafter referred to as the "control interval") is calculated as the amount of change in the compost temperature.

For example, the difference in compost temperature Tc over a 30-minute period is taken as the temperature change amount dTc. Since the compost temperature Tc is input at measurement intervals, if the measurement interval and control interval are the same, the change amount acquisition unit 31 stores the compost temperature input immediately before each input of the compost temperature Tc as the previous compost temperature Tcp, and the difference between them (Tc-Tcp) is taken as the temperature change amount dTc. If the measurement interval is shorter than the control interval, the compost temperature Tc at the timing that matches the control interval is used to calculate the temperature change amount dTc.

In addition, instead of the difference in compost temperature, the rate at which the compost temperature increases or decreases may be used as the amount of change in compost temperature. In addition, if the sensor device 20 is equipped with multiple temperature sensors, the control device 30 may input the compost temperatures detected by each temperature sensor, and the average value of the amounts of change in the compost temperatures may be used as the amount of temperature change dTc.

The ventilation control unit 32 determines the ventilation amount based on the temperature change amount dTc, and outputs the ventilation amount (signal) Am as information.
Aeration is standardized as the amount of air delivered per unit time per unit volume of compost material, for example, the amount of air (liters) delivered per minute per cubic meter.

The ventilation control unit 32 changes the ventilation amount stepwise in a predetermined range. For example, the ventilation amount range is 10 to 160 L/min/ ^m3 , the predetermined range is 10 L/min/ ^m3 , and the ventilation amount is changed in 16 steps (10, 20, ..., 160 L/min/ ^m3 ). In the following, the minimum ventilation amount is level 0, and each step up is level 2, level 3, .... In the case of 16 steps, the ventilation amount is level 0 to level 15, and the ventilation amount at level 0 is 10 L/min/ ^m3 , and the ventilation amount at level 15 is 160 L/min/ ^m3 . The ventilation control unit 32 holds information defining the ventilation amount at each level (hereinafter referred to as "level-specific ventilation amount information") in advance.

The ventilation control unit 32 sets a threshold value for the temperature change dTc, determines the ventilation level by threshold judgment, and outputs the ventilation level Am corresponding to the determined ventilation level using the level-specific ventilation level information.

The thresholds are set as follows: a threshold (first threshold) Th1 when the temperature change dTc is a positive number, i.e., when the compost temperature rises, and a threshold (second threshold) Th2 when the temperature change dTc is a negative number, i.e., when the compost temperature drops. If the temperature change dTc is equal to or greater than the threshold Th1, the ventilation rate is increased by one level, and if the temperature change dTc is equal to or less than the threshold Th2, the ventilation rate is decreased by one level. For example, the thresholds Th1 is set to 1.0°C, and Th2 is set to -0.1°C.
The threshold value can be determined by a preliminary experiment based on at least the state (type, amount, heat capacity, moisture content, aerobic microorganisms, etc.) of the compost material in the fermentation apparatus 10. The preliminary experiment may be performed using the above-mentioned compost production system, or a test system similar to the above-mentioned compost production system (for example, one that can simulate compost production conditions with a smaller amount of compost material than the above-mentioned compost production system).

The aeration control unit 32 determines the initial value of the aeration rate stage, i.e., the aeration rate stage at the start of composting, based on the compost temperature Tc at the start. For example, if the compost temperature Tc at the start is less than 10° C., the aeration rate stage is set to level 1 (20 L/min/m ³ ), if the compost temperature Tc is 10° C. or more and less than 20° C., the aeration rate stage is set to level 2 (30 L/min/m ³ ), if the compost temperature Tc is 20° C. or more and less than 30° C., the aeration rate stage is set to level 3 (40 L/min/m ³ ), and if the compost temperature Tc is 30° C. or more, the aeration rate stage is set to level 4 (50 L/min/m ³ ). The initial value of the aeration rate stage may be determined using settings other than these.

When changing the aeration amount based on a threshold judgment, rather than setting stages for the aeration amount, the aeration control unit 32 may directly change the aeration amount by increasing or decreasing the aeration amount by a predetermined amount (e.g., 10 L/min/ ^m3 ) relative to the aeration amount at that time. In this case, level-specific aeration amount information is not necessary, and the aeration amount is determined at the start of composting, rather than the aeration amount stage. The aeration control unit 32 may also change the aeration amount Am continuously rather than in stages, and when changing continuously, the aeration amount Am may be changed linearly or curvilinearly. The initial value of the aeration amount stage may be determined based on other information, such as the outside air temperature, rather than the compost temperature Tc, and the aeration amount stage may be reset at a predetermined time interval.

The aeration device 40 inputs the aeration volume Am output from the control device 30 and sends air according to the aeration volume Am to the compost material stored in the fermentation equipment 10.

An example of the configuration of the aeration device 40 is shown in Figure 4. The aeration device 40 includes a driving machine 41, a blower 42, an inlet pipe 43, an aeration pipe 44, and a communication cable 45. In order to supply air sent out from the blower 42 to the compost material in the fermentation equipment 10, the driving machine 41 controls the blower 42, and the air from the blower 42 is sent to the compost material via the inlet pipe 43 and the aeration pipe 44.

The driver 41 includes an inverter and outputs a control signal Sc for driving the blower 42 according to the input airflow Am. The inverter can convert DC or AC to AC of any frequency and voltage, so that power according to the airflow Am is output to the blower 42 as a control signal Sc to cause the blower 42 to blow out air corresponding to the airflow Am.

For example, the driver 41 holds in advance information that defines the frequency corresponding to the airflow volume based on the specifications and characteristics of the blower 42, and when the airflow volume Am is input, the driver 41 uses the information to determine an appropriate frequency. Then, it outputs a control signal Sc according to the determined frequency. The control signal Sc is input to the blower 42 via a communication cable 45. The inverter of the driver 41 performs modulation using a PWM (Pulse Width Modulation) method that varies the output by changing the pulse width, but other methods of modulation may also be used.

The frequency may be determined by the control device 30, rather than the driver 41. In this case, the control device 30 will output to the ventilation device 40 a frequency corresponding to the airflow volume Am, rather than the airflow volume Am. Also, rather than defining a frequency corresponding to the airflow volume, the frequency may be defined corresponding to the airflow volume stage. In this case, the control device 30 will output to the ventilation device 40 a stage of airflow volume, rather than the airflow volume Am.

The blower 42 draws in outside air, compresses it by the rotational motion of the impeller, etc., and sends it out. The blower 42 sends out an appropriate amount of air (airflow amount Am) by changing the strength of the rotational motion, etc., according to the input control signal Sc.

The supply pipe 43 is a pipe open at both ends, with one end fitted into the outlet (the port from which air is sent out) of the blower 42 and the other end fitted into the end of the ventilation pipe 44. The supply pipe 43 allows the air sent out from the blower 42 to flow into the ventilation pipe 44.

The ventilation pipe 44 is fitted into a groove 12 provided on the bottom surface of the storage section 11 of the fermentation equipment 10, and air sent from the ventilation pipe 44 is supplied to the compost material stored above the ventilation pipe 44. The length of the ventilation pipe 44 corresponds to the depth of the storage section 11 so that air is supplied to the entire compost material stored in the storage section 11. For example, if the depth of the storage section 11 is 270 cm, the length of the ventilation pipe 44 is approximately 260 cm. The outer diameter of the ventilation pipe 44 is set taking into consideration the appropriate supply of air to the compost material whether the amount of ventilation is large or small. For example, in this embodiment, the outer diameter of the ventilation pipe 44 is 10 cm.

The vent pipe 44 is a pipe that is open at one end and closed at the other end, and the open end is fitted into the end of the supply pipe 43. In addition, the vent pipe 44 has two parallel rows of vent holes 46 that are spaced at regular intervals in the axial direction (longitudinal direction).

Figure 5 is an enlarged view of the closed end of the ventilation pipe 44 as seen from the side where the ventilation holes 46 are drilled. As shown in Figure 5, two rows of ventilation holes 46 drilled in the axial direction at intervals of W1 are provided on the side of the ventilation pipe 44, with an interval of W2 between them. The diameter of the ventilation holes 46 and the intervals W1 and W2 are appropriately set taking into consideration the size (outer diameter, length) of the ventilation pipe 44 and the amount of air flow. In this embodiment, the diameter of the ventilation hole 46 is 5 mm, and the intervals W1 and W2 are 10 cm and 4 cm, respectively. In Figure 5, the ventilation holes 46 are drilled in a circumferentially aligned arrangement, but they may be drilled in a staggered arrangement in the circumferential direction. The ventilation pipe 44 may have one row or three or more rows.

Since compost material is piled up on top of the vent pipe 44, the vent pipe 44 is made of a material having the strength to withstand the weight of the piled compost material.
For example, a PVC pipe (rigid polyvinyl chloride pipe) is used as the ventilation pipe 44. PVC pipes are a piping material made of polyvinyl chloride, a synthetic resin, and are lightweight, impact resistant, chemical resistant, corrosion resistant, etc., and are used in a wide range of fields, such as sewer pipes, electrical conduits, and civil engineering. PVC pipes are broadly divided into VP pipes and VU pipes, and VP pipes, which are thick, are suitable for the ventilation pipe 44. Note that pipes other than PVC pipes, such as polyethylene pipes, may be used as the ventilation pipe 44 as long as they are made of a material that can be drilled with ventilation holes 46 and has the strength to withstand the weight of the compost material.

The vent pipe 44 is fitted into a groove 12 provided on the bottom surface of the storage section 11 of the fermentation equipment 10. Figure 6 shows an example of the state in which the vent pipe 44 is fitted into the groove 12. Since the vent pipe 44 is fitted into the groove 12, the side of the vent pipe 44 facing the groove 12 is not visible, but in Figure 6 the groove 12 is shown as a cross section cut in the vertical direction.

As shown in FIG. 6, the ventilation pipe 44 is fitted into the end of the supply pipe 43 inserted into a hole drilled in the back surface of the storage section 11, and is fitted into the groove 12 so that the ventilation hole 46 faces downward.
If the ventilation hole 46 faces upward, there is a risk that the ventilation hole 46 will be blocked by moisture leaking from the compost material, so to prevent this, the ventilation hole 46 faces downward. As a countermeasure against clogging of the piping, for example, sawdust 60 or the like may be placed on top of the ventilation piping 44, as shown in Figure 6.

A gap is formed between the ventilation pipe 44 and the bottom surface of the trench 12 so that the air sent out from the ventilation hole 46 can reach the compost material. For example, the ventilation pipe 44 is fitted into the trench 12 so that a gap of 5 mm is formed. Air that flows into the ventilation pipe 44 via the supply pipe 43 is sent out from the ventilation hole 46, and the air sent out from the ventilation hole 46 flows from the bottom surface of the trench 12 along the side to reach the compost material.

In this embodiment, the height at which the temperature sensor of the sensor device 20 is inserted, the control interval in the change amount acquisition unit 31 in the control device 30, and the thresholds Th1 and Th2 in the ventilation control unit 32 can be changed as appropriate, but appropriate values are set through experiments, etc. The temperature sensor height of 30 cm, control interval of 30 minutes, threshold Th1 of 1.0°C, and threshold Th2 of -0.1°C given as examples above are values obtained through preliminary experiments using the compost production system used in the examples described below.

An example of the operation of the compost production system 1 configured as above will be described with reference to the flowchart in Figure 7. Note that a description of general operations such as the operation when an error occurs will be omitted.

When the composting operation starts, the sensor device 20 detects the compost temperature Tc of the compost material stored in the fermentation equipment 10 and outputs it to the control device 30 (step S10).

In the control device 30, the compost temperature Tc is input to the change amount acquisition section 31 and the ventilation control section 32, and the change amount acquisition section 31 holds the input compost temperature Tc as the previous compost temperature Tcp (step S20).
The aeration control unit 32 determines the aeration rate level based on the input compost temperature Tc (step S30). That is, when the compost temperature Tc is less than 10° C., the aeration rate level is set to level 1, when the compost temperature Tc is 10° C. or more and less than 20° C., the aeration rate level is set to level 2, when the compost temperature Tc is 20° C. or more and less than 30° C., the aeration rate level is set to level 3, and when the compost temperature Tc is 30° C. or more, the aeration rate level is set to level 4.
Then, the ventilation control unit 32 uses the level-based ventilation amount information to output the ventilation amount Am corresponding to the determined ventilation amount stage to the ventilation device 40 (step S40).

In the ventilation device 40, the driver 41 inputs the ventilation volume Am, determines a frequency corresponding to the ventilation volume Am, and outputs power according to the determined frequency as a control signal Sc to the blower 42 (step S50).

The blower 42 blows out an amount of air based on the input control signal Sc, and the blown out air is supplied to the compost material stored in the storage section 11 of the fermentation equipment 10 via the supply pipe 43 and the ventilation pipe 44 (step S60).

When the measurement interval has elapsed, the sensor device 20 detects the compost temperature Tc of the compost material and outputs it to the control device 30 (step S70).

In the control device 30, the compost temperature Tc is input to the change amount acquisition unit 31. If the input compost temperature Tc is data for a timing that matches the control interval (step S80), the change amount acquisition unit 31 calculates the difference between the compost temperature Tc and the stored previous compost temperature Tcp (Tc-Tcp), outputs this as the temperature change dTc to the ventilation control unit 32 (step S90), and stores the compost temperature Tc as the previous compost temperature Tcp (step S100). If the compost temperature Tc is not data for a timing that matches the control interval (step S80), the change amount acquisition unit 31 does not perform the operations of steps S90 and S100 above, and waits for the input of the next compost temperature Tc.

The ventilation control unit 32 calculates the ventilation amount Am based on the amount of temperature change dTc.
If the temperature change amount dTc is equal to or greater than the threshold Th1 (step S110), the ventilation control unit 32 increases the ventilation level by one (step S120), and if the temperature change amount dTc is equal to or less than the threshold Th2 (step S130), the ventilation control unit 32 decreases the ventilation level by one (step S140). In other cases, the ventilation level remains unchanged. Then, the ventilation control unit 32 uses the level-specific ventilation information to output the ventilation level Am corresponding to the determined ventilation level to the ventilation device 40 (step S150).

Note that step S120 includes an operation of not increasing the ventilation level if the ventilation level is at the maximum ventilation level and cannot be increased any further, and step S140 includes an operation of not decreasing the ventilation level if the ventilation level is zero and cannot be decreased.

The aeration device 40, which has received the aeration volume Am, supplies air to the compost material stored in the storage section 11 of the fermentation equipment 10 by the same operations as steps S50 and S60 (steps S160, S170).

The operations of steps S70 to S170 described above are repeated at measurement intervals.
Composting ends when the compost temperature does not rise to a high temperature even after turning, when a predetermined period of time (e.g., three months) has passed (step S180), etc., and operation of the compost production system 1 also ends with the end of composting.

In the above operations, the order of steps S20 and S30, steps S90 and S100, steps S110 to S120 and steps S130 to S140, etc. can be changed as appropriate.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications are possible within the scope of the gist of the present invention. Furthermore, matters not explicitly disclosed in the above-mentioned embodiment, such as the size of the blower, do not deviate from the scope of what a person skilled in the art would normally do, and values that a person skilled in the art would be able to easily imagine can be used.

For example, the following modifications are possible to this embodiment.
Compost production system 1 uses compost temperature as environmental information and performs change-rate aeration control based on the amount of change in compost temperature to perform composting, but it is also possible to use the amount of oxygen in the compost material as environmental information and perform change-rate aeration control based on the amount of change in the oxygen amount to perform composting.
Aerobic microorganisms use oxygen in the air to ferment compost materials, and the compost temperature rises due to the heat of fermentation caused by the fermentation of the compost materials, so the amount of oxygen in the compost materials and the compost temperature are closely related. Therefore, variable aeration control can be performed using the amount of oxygen instead of the compost temperature. In this case, the sensor device detects the amount of oxygen (oxygen concentration) in the compost material stored in the storage section of the fermentation equipment. The sensor device is equipped with an oxygen meter (oxygen concentration meter) and measures the amount of oxygen by inserting the oxygen meter into the piled compost material.

The compost production system 1 constantly aerates the compost material, and variable aeration control is performed by increasing or decreasing the amount of aeration, but it is also possible to perform variable aeration control by adjusting the time for aeration rather than increasing or decreasing the amount of aeration. That is, instead of constantly aerating the compost material, variable aeration control is performed by setting a time for aeration and a time for no aeration, and adjusting both times. If a large amount of aeration is required, the time for aeration is lengthened, and if a small amount of aeration is sufficient, the time for no aeration is lengthened. In this case, the control device does not output the amount of aeration to the aeration device, but rather outputs information for adjusting the time for the aeration device to aerate (e.g., the time for aeration).

The compost production system 1 uses ventilation pipes 44 fitted into grooves 12 provided on the bottom surface of the storage section 11 of the fermentation equipment 10 for ventilation, but ventilation may also be achieved by supplying air from above and/or the sides of the piled compost material, or even from inside the piled compost material.

In addition, while the compost production system 1 composts livestock waste from cows, pigs, etc., it is also capable of composting other organic waste such as sludge and food waste.

Although the above-mentioned embodiment has been described in the form of a system or device, the present invention can also take the form of a method or program. In addition, the compost production program of the present invention is stored in the control device 30, but the compost production program of the present invention may be stored in a storage medium readable by an external computer, and the compost production system may be configured to operate via the external computer. In addition, all or part of the fermentation equipment, sensor device, and aeration device may be configured using existing equipment and/or commercially available devices.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these.

A composting experiment (hereinafter referred to as an "experiment with aeration control") was conducted under the following conditions using a composting system having a configuration similar to the composting system 1 according to the embodiment of the present invention shown in Figures 1 to 7.
- Use cow dung as compost material.
- Compost material is piled up to a height of approximately 150 cm, and three temperature sensors are inserted at heights of 120 cm, 60 cm, and 30 cm from the bottom of the storage section 11 (hereinafter referred to as "sensor 1,""sensor2," and "sensor 3" in order of increasing position), and sensor 3 is used as the temperature sensor for the sensor device 20.
The control interval is 30 minutes, and the difference in compost temperature over 30 minutes is the amount of temperature change.
Threshold values Th1 and Th2 for the amount of temperature change are set to 1.0° C. and −0.1° C., respectively (determined through preliminary testing).
- Turn it over once a week.
-Composting takes place in winter (late December to mid-April).

For comparison, an experiment was also conducted in parallel in which the compost materials, compost material height, turning timing, and composting period were adjusted to the above conditions, and an aeration rate of 100 L/min/ ^m3 of air was constantly supplied to the compost materials (hereinafter referred to as the "experiment with conventional aeration"). Of the two storage sections of the fermentation equipment, an experiment with aeration control was conducted in one storage section 11a, and an experiment with conventional aeration was conducted in the other storage section 11b.

The change in compost temperature over the course of five weeks from the start of composting is shown in Figure 8. Figure 8(A) is a graph showing the results of an experiment using conventional aeration, and Figure 8(B) is a graph showing the results of an experiment using controlled aeration.
In addition to the compost temperatures measured by sensors 1, 2 and 3, Figures 8(A) and (B) show the change in air temperature over time, and Figure 8(B) also shows the aeration rate. The horizontal axis of Figure 8 is the period (unit: weeks), the vertical axis of Figure 8(A) is the temperature (unit: °C), and the vertical axis of Figure 8(B) is the temperature and aeration rate (unit: L/min/ ^m3 ).

As shown in Figure 8 (A), in the experiment with conventional aeration, after the start of composting there was a sudden rise and then a large drop in the compost temperature. Thereafter, there were times when the compost temperature rose due to the activation of aerobic microorganisms caused by turning the compost, but overall the compost temperature fell.
In the experiment using conventional aeration, an aeration volume of 100 L/min/ ^m3 of air was constantly supplied to the compost material, resulting in over-aeration, where more aeration than was necessary was ventilated. As the compost temperature measured by sensors 2 and 3 was sometimes lower than the air temperature, it is presumed that the compost temperature was much lower than when aeration was not performed.

In contrast, in the experiment with aeration control, as shown in Figure 8 (B), the compost temperature rose sharply after composting began, but the extent of this rise was less than in the experiment with conventional aeration. This is presumably because the sudden rise in compost temperature caused a sudden increase in the aeration rate, as shown in Figure 8 (B), which cooled the compost materials and prevented the rise in compost temperature from occurring. Then, as the compost temperature changed from a sudden rise to a decline, the aeration rate decreased, preventing excessive aeration, and as a result, the compost temperature rose again.
After that, the compost temperature drops sharply temporarily when the compost is turned, but then recovers rapidly. This is thought to be because the aeration rate is zero when the compost is turned, and the activity of aerobic microorganisms causes the compost temperature to rise sharply. The sudden rise in compost temperature then causes aeration, but as the compost temperature drops, the aeration rate drops again to zero, preventing excessive aeration and a drop in the compost temperature. In this way, high-temperature fermentation is maintained in the experiment with aeration control.

FIG. 9 shows the time course of the compost temperature and the time course of the oxygen concentration in the compost material in an experiment in which the composting period was extended.
As in the case of FIG. 8, FIG. 9(A) is a graph showing the results of an experiment with conventional ventilation, and FIG. 9(B) is a graph showing the results of an experiment with controlled ventilation, with the oxygen concentration (unit: %) added to the vertical axis.

In the experiment using conventional ventilation, as shown in Figure 9 (A), in the latter half of the composting period, the change in compost temperature was roughly synchronized with the air temperature. This is presumably because the activity of aerobic microorganisms had calmed down, and in this state, aerating the compost at the same rate as in the first half of the composting period would result in unnecessary costs such as increased power consumption. The oxygen concentration did not change significantly throughout the composting period, remaining at a high level similar to that in the atmosphere.

In contrast, in the experiment with aeration control, as shown in Figure 9 (B), the compost temperature generally decreased slowly up to the 10th week, and then generally increased slowly. Since the aeration rate was nearly zero from the 5th week onwards, it is presumed that the change in compost temperature during this period was the same as that observed in general composting where only turning was performed. The oxygen concentration decreased when the compost temperature increased. This is presumed to be due to the increased activity of aerobic microorganisms caused by the increase in compost temperature.

The changes in moisture (moisture content) and organic matter decomposition rate over time in the compost material in the experiment with aeration control and the experiment with conventional aeration are shown in Figures 10 and 11, respectively. The horizontal axis is the period (unit: weeks), and the vertical axis is moisture (unit: %) in Figure 10 and organic matter decomposition rate (unit: %) in Figure 11.

As shown in FIG. 10, the change (decrease) in moisture in the experiment with aeration control was slower than in the experiment with conventional aeration, indicating that composting was taking place appropriately.
As for the organic matter decomposition rate, as shown in FIG. 11, the organic matter decomposition rate in the experiment with aeration control remained higher than in the experiment with conventional aeration, indicating that appropriate composting was taking place.

Furthermore, good results were obtained even when ventilation control experiments were conducted in the summer (late July to early September).

REFERENCE SIGNS LIST 1 compost production system 10 fermentation equipment 11, 11a, 11b storage section 12, 12a, 12b, 12c, 12d groove 20 sensor device 30 control device 31 change amount acquisition section 32 aeration control section 40 aeration device 41 driver 42 blower 43 feed pipe 44 aeration piping 45, 51, 52 communication cable 46 vent 60 sawdust

Claims (11)

A method for producing compost, comprising at least controlling ventilation of a compost material so that the compost material is at least at a predetermined temperature,
a change amount acquisition step of determining an amount of change in environmental information, which is information regarding a temperature or an oxygen concentration of the compost material;
and controlling aeration of the compost material;
A compost production method characterized in that, in the aeration control step, after setting an initial value, a constant control is performed based only on the amount of change in the environmental information, independent of the value of the environmental information . using the temperature of the compost material as the environmental information;
The method for producing compost according to claim 1 , wherein the change amount obtaining step obtains the amount of change in temperature. In the ventilation control step,
increasing aeration of the compost material if the change in temperature is equal to or greater than a first threshold;
The method for producing compost according to claim 2 , further comprising reducing the amount of ventilation when the amount of change in temperature is equal to or less than a second threshold value. The compost production method according to claim 3, wherein the first threshold value and the second threshold value are determined based on at least the state of the compost material. The compost production method according to claim 1, in which aeration is controlled so that the temperature of the compost material is 60°C or higher. The compost production method according to claim 1, wherein the compost material is cow dung and/or swine manure. The compost production method according to claim 2, wherein in the ventilation control step, the initial value is determined based on the temperature. A control device for use in the compost production method according to any one of claims 1 to 7,
A control device comprising: a change amount acquisition unit that executes the change amount acquisition step; and an airflow control unit that executes the airflow control step. A composting system comprising the control device according to claim 8,
A compost production system further comprising a fermentation facility having a storage section for storing the compost material and fermenting it, a sensor device for detecting the environmental information, and an aeration device for aerating the compost material based on information output from the control device. A compost production program for at least controlling ventilation of a compost material so that the compost material reaches a predetermined temperature or higher in the production of compost,
On the computer,
a change amount acquisition step of determining an amount of change in environmental information, which is information regarding a temperature or an oxygen concentration of the compost material;
and controlling aeration of the compost material.
A compost production program characterized in that, in the aeration control step, after an initial value is set, a constant control is performed that is not dependent on the value of the environmental information, but is based only on the amount of change in the environmental information. A computer-readable recording medium having the compost production program according to claim 10 recorded thereon.