JP2017211374A - Decay degree determination method of compost, and composting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine objectively the decay degree of compost in chemical property, and to perform composting through the decay degree determination.SOLUTION: Composting can be performed by steps for: mixing raw material containing organic waste; fermenting the raw material, while agitating it; aging the fermented raw material; and determining the decay degree based on a decay degree determination method of compost. In determination of the decay degree, it is determined whether prescribed decay conditions in chemical property of the compost are satisfied or not.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for determining the degree of maturity of compost and a method for composting.

  In recent years, recycling of organic waste including food waste has become increasingly important. One effective use of organic waste is composting. Conventionally, composting of organic waste has mainly been managed based on the intuition and experience of composting workers and farmers, but in the future, in order to ensure the safety of crops, compost quality There is a need for rapid and accurate assessment methods.

  One quality of compost is the maturity of compost. When immature compost, which has not progressed in maturity, is applied to soil, it is accompanied by indirect damages such as generation of high-concentration inorganic nitrogen, abnormal reduction of soil, and nitrogen starvation, along with rapid decomposition of organic matter in the soil. There is a risk that the growth of crops may be hindered by a direct hindrance effect due to the release of inhibitors and the like. For this reason, before applying compost to soil, it is necessary to grasp the maturity of compost. For example, Patent Document 1 proposes a method for determining the degree of maturity of compost based on the amount of weak light emitted from the compost extract.

JP-A-2005-274222

  The maturity of compost is evaluated in terms of physical and chemical properties. The determination of the degree of maturity related to physicality is to determine the effect of applying an appropriate amount of air by applying compost to the soil to soften the soil (this is a soil improvement effect and is also referred to as swelling and softening). Determination of the degree of maturity related to chemicals can be achieved by detoxifying growth inhibitors (lower fatty acids, phenols, etc.), which are intermediate products during decomposition, as the degree of decomposition of readily degradable organic matter in the compost progresses. The effect of acting as a nutrient on agricultural products by slowly decomposing organic matter (the effect of supplying fertilizer elements mainly of slow release) is determined. When composting workers and agricultural workers look at the degree of compost completion, the so-called subjective judgment method of checking the degree of chemical maturity by visual and olfactory senses and checking the degree of physical maturity by tactile sense remains. This is the current situation.

  Then, this invention aims at providing the method of judging the maturity of compost objectively in chemical nature, and also providing the method of composting through these maturity judgments. .

In order to solve the above problems, the present invention provides a step of obtaining an integrated temperature after starting fermentation of compost containing organic waste as a raw material, and a step of performing a germination test using compost having different integrated temperatures. And a step of obtaining a correlation between the integrated temperature and a GI value (Germination index) based on the germination test, and applying the integrated temperature of the compost to be determined to the correlation, the degree of maturity in the chemical properties of the compost A method for determining the degree of maturity of compost. Here, in the correlation, the integrated temperature when the GI value is 50% may be 1500 ° C.
The present invention also includes a step of mixing raw materials containing organic waste, a step of fermenting the raw materials, a step of aging the fermented raw materials, and the maturity determination method of at least one of the above composts. A composting method comprising: a step of determining a degree of maturity based on the method.

  According to the present invention, it is possible to objectively determine the degree of maturity of compost in terms of chemistry, and to perform composting through these determinations.

Process drawing which shows the composting method which concerns on embodiment. The process figure which calculates | requires the correlation of integrated temperature and GI value. The graph which shows the relationship between the elapsed days from the time of starting a fermentation process (horizontal axis: composting days [day]) and the daily average temperature (vertical axis: temperature [degrees C]) of the measurement temperature of compost. Elapsed days from the start of the fermentation process (horizontal axis: composting days [days]) and daily average temperature of composted measurement temperature (vertical axis: integrated temperature) [° C./day]). Obtained as a result of the germination test of Komatsuna using samples collected from composted products with different integrated temperatures (horizontal axis: integrated temperature [° C / day]) from the start of the fermentation process. The graph which shows correlation with the obtained GI value (here Zucconi's GI value) (vertical axis: GI [%]). The figure which shows the particle size accumulation curve for every composting days. Process drawing which shows a compression test. Explanatory drawing which shows the specific example of a compression test. The graph which shows the relationship between the maturity of compost (horizontal axis: [%]) and the amount of settlement (vertical axis: [%]). The graph which shows the relationship between the maturity of compost (horizontal axis: [%]) and unit volume weight (vertical axis: [%]). The graph which shows the relationship between the maturity of compost (horizontal axis: [%]) and the weight percentage of 2 mm or less (vertical axis: [%]).

  An example for carrying out the present invention will be described. In the following description, “compost” is an agricultural production material used in expectation of soil improvement effect and fertilizer element supply effect. “Maturation of compost” means that when compost is applied to the soil, the obstacle to the growth of the crop is small, and by applying the compost, energy is given to microorganisms in the soil to activate the activity directly or indirectly. In particular, the organic matter in the compost must be rotted in advance to such an extent that it is linked to the maintenance of geological strength and does not cause adverse changes in the soil environment. And when it ripens to such a state, it is the end of ripening, that is, final ripening, and the degree of ripening until it reaches such a state is called “maturity”. The maturity degree related to physical properties mainly contributes to the soil improvement effect, and the maturity degree related to chemical properties mainly contributes to the supply effect of fertilizer elements.

(1) Overview of Composting Method FIG. 1 is a process diagram showing a composting method according to the present embodiment. In FIG. 1, the main steps for composting will be described. First, a pretreatment / mixing step is performed (step S1). Specifically, organic waste such as food waste received by a worker from a food factory or the like is used as a raw material, and this is mixed with auxiliary materials such as wood chips. This mixture is hereinafter referred to as “compost”.

  Next, a fermentation process is performed (step S2). Specifically, the worker moves the inside of the fermentation facility while periodically stirring the compost by, for example, an automatic stirring and conveying machine or other working machines. In addition, air may be supplied by a blower from the bottom side of the fermentation facility. The period required for this fermentation process is, for example, about 25 days.

  Next, an aging process is performed (step S3). Specifically, an operator piles up compost in a maturation facility up to a height of several meters, and periodically performs a work such as turning over with a wheel loader or other work machine in units of one pile. In addition, air may be supplied by a blower from the bottom side of the fermentation facility. The period required for this aging step is, for example, about 95 days. In the present embodiment, the mixing and stirring work of the composted product in the fermentation process is referred to as “stirring”, and the mixing and stirring work of the composted product in the aging process is referred to as “turning back” to distinguish them.

  Next, a maturity determination process is performed for determining whether the composted material satisfies predetermined maturation conditions in physical properties and chemical properties as compost (step S4). Steps S10 and S20 relating to the maturity determination process will be described in detail later.

  When it is determined that the ripening conditions are satisfied (step S4; YES), a commercialization process such as sieving and storage is performed by the worker (step S5). Thereby, it will be in the state which can be shipped as a compost as a product.

(2) Chemical ripening conditions for step S10 In the fermentation and ripening process, the temperature rises with the decomposition of organic matter by microorganisms, but generally this temperature can be measured and recorded for the management of composting work. Has been done. However, the temperature measured at this time is data that assists the intuition and experience in confirming the degree of maturity of the compost, but based on this, it is necessary to quantify the progress of composting. Has not reached so far. The present inventors made a hypothesis that there is some correlation between the accumulated temperature of compost and a so-called GI (Germination index) value, and determined the degree of maturity in compost chemistry based on the accumulated temperature. Tried to establish a method.

  In the fermentation and aging process, stirring or turning is performed so that the compost is uniform, but some properties (temperature, etc.) of the compost are affected by the atmosphere (temperature) in the vicinity of the surface layer. For this reason, a temperature of 30 cm 2 from the surface of the compost is listed as one of the quality confirmation criteria for the compost. In order to grasp the depth that is not affected by the atmosphere, the present inventors measured the temperature of the compost at different depths throughout the composting process in time series (specifically, approximately 10 minutes apart). 8 months). As a result, it was found that the temperature was stable at a depth of 70 cm or more from the surface, so the measurement depth of the temperature of the compost was set to 70 cm.

  Moreover, in the composting process, the temperature of the composted material is lowered, raised, and stabilized by stirring or turning over. The present inventors considered the time when the temperature of the compost is stable as the time when the property of the compost is stable, and examined the time zone suitable for the investigation in the work time zone in the composting process. Specifically, for the measured temperature of 70 cm in depth, the daily average temperature and the average temperature for every hour are calculated and compared, and a significant difference (here, 1) It was confirmed that the time zone without the (% rejection area) was 0-8 o'clock, 18: 00-23: 00. This is because the composting process usually involves stirring or turning in the morning, so the temperature was assumed to be stable after 18:00 after a certain period of time had elapsed from that work. Therefore, a time zone suitable for temperature measurement for grasping the properties of compost was set after 8 hours had passed after the stirring or turning operation until the next stirring or turning operation.

  In the composting process, a moderately high temperature is required to kill pathogenic bacteria and weed seeds. However, if the temperature is too high, microorganisms effective for composting are also affected. Considering these things, the management target value of the temperature of the compost was set to 60 to 75 ° C. in the fermentation process and 50 to 75 ° C. in the aging process.

  Here, FIG. 2 is a process diagram for obtaining the correlation between the integrated temperature and the GI value. First, an operator calculates | requires the integrated temperature after starting fermentation of a compost | cure material (step S11), performs a germination test using each compost from which integrated temperature differs (step S12), and is based on integrated temperature and a germination test. A correlation with the value (Germination index) is obtained (step S13).

  FIG. 3 shows the relationship between the number of days elapsed since the start of the fermentation process (horizontal axis: composting days [days]) and the daily average temperature of the composted measurement temperature (vertical axis: temperature [° C.]). It is a graph. Moreover, FIG. 4 shows the integrated result (vertical axis) of the number of days elapsed since the start of the fermentation process (horizontal axis: days of composting [days]) and the daily average temperature of the measured compost from the start of the fermentation process. : Accumulated temperature [° C./day]). In addition, FIG. 5 shows a germination test using samples collected from compost having different integrated temperatures (horizontal axis: integrated temperature [° C./day]) from the start of the fermentation process. It is a graph which shows correlation with the GI value (here, the GI value of zucchini) (vertical axis: GI [%]) obtained from the result of having performed the seed of Komatsuna. 3 to 5 are graphs obtained by steps S11 to S13 of FIG.

  3 and 4, the temperature at the time of measurement was generally within the range of the management target value, but the integrated temperature was slightly higher than the management target value. In addition, when the composting period was 120 days, the trend of increase in accumulated temperature slowed down, and the accumulated temperature at that time was about 8,800 [° C./day]. 4 and 5, it was found that the GI value exceeded 50%, which is the minimum standard at which compost can be shipped as a product, at 21 days of composting. The accumulated temperature at this time is about 1,500 [° C./day].

  Therefore, it can be said that the compost maturity condition in the chemical nature is satisfied when the composting days of 21 days, that is, when the cumulative temperature exceeds 1,500 [° C. · day]. That is, if the integrated temperature of the compost that is the target for determining the maturity level is applied to the correlation between the integrated temperature and the GI value shown in FIG. 5, the maturity level in chemistry can be determined.

Therefore, in step S10 of FIG. 1 described above, temperature measurement and integration are performed on the compost that is the target of maturity determination. Then, in step S4, using the accumulated temperature, the determination regarding the maturity condition of compost in the above-described chemistry (whether the accumulated temperature exceeds 1,500 degrees) is performed. Here, when the integrated temperature exceeds 1,500 degrees, it is determined that the compost maturity condition in chemical properties is satisfied.
The above embodiment is only an example of the present invention, and various modifications can be made in the implementation of the present invention. For example, the relationship between the integrated temperature and the GI value may be corrected according to, for example, the compost material.

(3) About physical maturation conditions regarding step S20 The maturity regarding physicality mainly contributes to the soil improvement effect (so-called swelling and softening). The present inventors have hypothesized that the compost is decomposed and the particle size is reduced in the ripening process, so that when mixed with the soil, it enters the gap between the soils, and as a result, the soil becomes soft.

(3-1) Particle size analysis Samples from compost are collected every composting period, and particle size analysis (based on JIS A 1204, which defines the soil particle size test method) is performed in order to extract the particle size that varies greatly due to composting. went. FIG. 6 is a diagram showing a particle size accumulation curve for each composting day. From FIG. 6, it was found that the organic waste was subdivided as composting progressed, and the change in particle size was particularly large in the range of 0.85 to 2 mm. From this, it was confirmed that the weight percentage of the sample collected from the compost was passed through a 2 mm mesh sieve could serve as an index for the composting process. This is thought to be due to decomposition and fragmentation of persistent organic substances such as wood (hemicellulose, cellulose) and lignin.

(3-2) Compression test A compression test was conducted to measure the amount of settlement when a load was applied to a sample collected from compost. In this test, as shown in FIG. 7, the sample is packed in a cylindrical container (see FIG. 8) having an inner diameter of 10 cm and a height of 20 cm so that no compaction force is applied (step S21), and 3.2 kg. A weight (0.4 kN / m ² ) was applied with a weight (step S22), the amount of settlement was measured, and the ratio (%) to the total height (20 cm) was calculated (step S23). As a sample at the time of this compression test, a 15 mm mesh screen from which impurities were removed was used. Moreover, the unit volume weight of the sample and the weight percentage [%] below the particle size having a large change obtained by particle size analysis were calculated.

Furthermore, subjective compost maturity was judged based on the experience of skilled composting workers and compared with the results of the compression test described above. The degree of maturity was in the range of 0 to 100% for each pile of compost in the ripening process (0% was the state at the beginning of composting and 100% was composted). As shown in FIG. 9, from the relationship between the degree of compost maturity and the amount of subsidence in the compression test, as the composting, that is, the degree of maturity , the ratio of the amount of subsidence during compression to the total amount of compost before compression tends to decrease. It was. When the degree of maturity was 100%, the ratio of settlement was 15.1% on average (standard deviation σ = 1.536). Further, as shown in FIGS. 10 and 11, the unit volume weight and the weight percentage of 2 mm or less tended to increase as composting, that is, the degree of maturity progressed. The unit volume weight is changed from 0.38 / cm ³ (σ = 0.012) to 0.47 g / cm ³ (σ = 0.005) for the change of compost maturity from 15% to 100%. A change in weight percentage of 2 mm or less from 30.07% (σ = 3.892) to 60.08% (σ = 2.218) was observed.

As described above, when a load is applied to the compost relative to the total amount of the compost when the load is not applied to the compost placed in the container and the compost containing organic waste as a raw material The compost maturity level of the compost is determined by comparing the measured ratio with the target ratio, and determining the maturity level of the compost physical property. Whether or not the condition is satisfied can be determined. In Figure 1 described above, it performs compression tested compost as the maturity of the determination target (step S20), in step S 4, and comparing the ratio to form the ratio and the target of the settlement amount measured by the compression test Then, the maturity in the physical properties of the compost is judged (whether or not the rate of settlement will exceed the target 15%). Here, when the ratio of the sinking amount is less than the target 15%, it is determined that the maturity condition in physical properties is satisfied.

According to the embodiment described above, the maturity of compost can be determined more objectively than conventional in terms of physicality or chemical properties. Furthermore, a step of mixing raw materials containing organic waste, a step of fermenting the raw materials while stirring, a step of aging the fermented raw materials, and a step of determining the maturity based on the method for determining the maturity of compost By this, it becomes possible to perform composting that is sufficiently matured.
The above embodiment is only an example of the present invention, and various modifications can be made in the implementation of the present invention. For example, in the compression test, the load condition due to the weight may be changed according to the material of compost, for example.

1 container, 2 weights.

Claims (3)

A process for obtaining an integrated temperature after starting fermentation of compost containing organic waste as a raw material;
A step of performing a germination test using each of the composts having different integrated temperatures;
Obtaining a correlation between the integrated temperature and a GI value (Germination index) based on the germination test;
Applying the accumulated temperature of the compost to be determined to the correlation, and determining the maturity in the chemical properties of the compost. In the correlation, the integrated temperature when the GI value is 50% is 1500 ° C. Mixing raw materials including organic waste,
Fermenting the raw material;
Aging the fermented raw material;
And a step of determining a maturity level based on the method for determining a maturity level of compost according to claim 1 or 2.

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