JP5519069B1 - Method for determining the amount of hydrogen sulfide inhibitor added - Google Patents

Abstract

The present invention provides a technique for determining an addition amount of a hydrogen sulfide inhibitor to be added to soil in order to suppress generation of hydrogen sulfide in the soil and containing zinc oxide.
SOLUTION: A step of extracting a part of soil as a soil sample, a step of measuring a weight X of the soil sample and a weight ΔX of an organic component in the soil sample, and an organic component actually contained in the soil The step of calculating the actual organic component content A and the setting of the weight Y of the part of the soil that is to be stirred and then mixed with the hydrogen sulfide inhibitor after being added with the hydrogen sulfide inhibitor And a step of determining a hydrogen sulfide inhibitor addition amount ΔY so as to have a numerical value equal to or greater than (A · Y · R) / D) (R: reference value, D: zinc oxide in the hydrogen sulfide inhibitor) Actual zinc oxide content actually contained).
[Selection] Figure 19

Description

  The present invention relates to a technique for determining the addition amount of a hydrogen sulfide inhibitor to be added to soil in order to suppress generation of hydrogen sulfide in the soil and containing zinc oxide.

  It is known that hydrogen sulfide is a harmful substance for humans, animals and plants. For example, in certain environments, there are anaerobic microorganisms that are capable of generating hydrogen sulfide from sulfur sources under anaerobic conditions (which are microorganisms that inhabit the natural world and are also referred to as sulfate-reducing bacteria and sulfate-reducing bacteria). Yes. It is also known that hydrogen sulfide is generated when a sulfur source, an organic component serving as a nutrient component of anaerobic microorganisms, and moisture coexist in the environment. Examples of environments in which harmful hydrogen sulfide can be generated include manholes with a large amount of organic components, sewers, underground construction sites, swamps, waste disposal plants, paper mills, and seafood processing plants.

In recent years, waste materials of gypsum board, that is, waste gypsum board, are expected to increase in emissions with an increase in the dismantling of buildings and the like. Waste gypsum board contains a sulfur source (derived from calcium sulfate (CaSO ₄ ) constituting the main component of the core material) in its core material, and an organic component (for example, starch paste) in its adhesive Contains. Therefore, when this waste gypsum board is discarded in a landfill disposal site where soil is in a wet state and satisfies anaerobic conditions, hydrogen sulfide is generated. Therefore, there is a strong demand for suppressing the generation of hydrogen sulfide when landfilling waste gypsum board.

  For waste gypsum board, which is expected to increase in the future, the landfill site is expected to be tight. Therefore, recycling of waste gypsum board is also promoted. Specifically, for example, waste gypsum board has already been crushed and recycled as a soil conditioner. The soil conditioner is added to the soil to solidify or granulate the soil to be regenerated. When this type of soil conditioner is used in the agricultural field or the like, the growth of hydrogen sulfide may cause poor growth due to root rot of plants. Therefore, when trying to recycle waste gypsum board as a soil conditioner, there is a strong demand for suppressing the generation of hydrogen sulfide.

  On the other hand, Patent Document 1 discloses a technique for suppressing the generation of hydrogen sulfide using zinc oxide. Specifically, the document describes an interior material containing gypsum and hydrogen sulfide for the purpose of suppressing the release of hydrogen sulfide from the interior material into the room even when the interior material is placed in a wet state. A surface coating composition containing zinc oxide as a metal compound capable of forming a stable sulfide by reacting with hydrogen sulfide is applied to a building, and the hydrogen sulfide generated by sulfur-containing components contained in the building and the oxidation A technique for reacting with zinc is disclosed.

Japanese Patent Publication No. 1-44737

  In an environment where hydrogen sulfide is likely to be generated due to the coexistence of a sulfur source, organic components, moisture, and anaerobic microorganisms capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions. Research was conducted on the products used to suppress the generation of hydrogen sulfide. Such products include, for example, gypsum board, soil conditioners, sewage pipes, drainage grooves (eg, U-shaped grooves) that contain objects in motion, drainage pits that substantially contain objects Some of them are housed in a static state.

  In order to develop a method for appropriately determining the amount of zinc oxide or zinc to be contained in this type of product (hereinafter referred to as “content of zinc oxide or the like”), An experiment was conducted on a sample of the product having a content such as zinc oxide, and as a result, the relationship between the actual generation amount (concentration) of hydrogen sulfide from the product and the content (content rate) of zinc oxide, etc. Was actually measured.

  As a result, we select the ratio of zinc oxide or zinc to the organic component as an effect control factor, and by controlling the selected effect control factor, the amount of zinc oxide or zinc is It was found that it is desirable to determine relative to the target concentration of the hydrogen sulfide and the amount of the organic component.

  Based on this knowledge, the present invention provides a technique for determining the addition amount of a hydrogen sulfide inhibitor that contains zinc oxide to be added to the soil in order to suppress the generation of hydrogen sulfide in the soil. It was made as an issue.

In order to solve the problem, according to the first aspect of the present invention, hydrogen sulfide can be generated from a sulfur source, an organic component mainly composed of carbon, moisture, and anaerobic conditions. In order to suppress the generation of hydrogen sulfide from the soil that is placed in an environment where hydrogen sulfide is easily generated due to the coexistence of anaerobic microorganisms and contains the organic component, a hydrogen sulfide inhibitor is added to the soil. A method for determining a hydrogen sulfide inhibitor addition amount for determining an addition amount for adding a material containing zinc oxide,
The soil contains a sulfur source such that the ratio of the sulfur source contained in the soil to the weight of the organic component in the soil is 0.54% by weight or more when the weight of the sulfur source contained therein is measured as the weight of calcium sulfate. And
The hydrogen sulfide inhibitor contains substantially no organic component as a hydrogen sulfide generating component, while containing zinc oxide as a hydrogen sulfide suppressing component,
The method for determining the amount of hydrogen sulfide inhibitor added is as follows:
Prior to the addition of the hydrogen sulfide inhibitor to the soil, an extraction step of extracting a part of the soil to which the hydrogen sulfide inhibitor is to be added as a soil sample;
A measuring step of measuring the weight X of the extracted soil sample and the weight ΔX of the organic component contained in the soil sample;
The ratio of the measured value of the weight ΔX of the organic component to the measured value of the weight X of the soil sample is expressed as the actual organic component content A (= ΔX / X) in which the organic component is actually contained in the soil sample . ) As a calculation process,
A setting step of setting a mixed soil weight Y that is the weight of a portion of the soil that is to be stirred and mixed with the hydrogen sulfide inhibitor after the hydrogen sulfide inhibitor is added;
The hydrogen sulfide inhibitor addition amount ΔY, which is the weight of the hydrogen sulfide inhibitor to be added to the soil, is the product of the actual organic component content A, the mixed soil weight Y, and a predetermined reference value R. (= A · Y · R) divided by the actual zinc oxide content D (= ΔZ / Z) in which the zinc oxide is actually contained in the hydrogen sulfide inhibitor (= (A · Y · R) R) / D) and determining to have a numerical value equal to or greater than the divided value (= (A · Y · R) / D) ,
The reference value R is a hydrogen sulfide inhibitor addition amount determining method that means a lower limit value of a range of a ratio of the weight of the zinc oxide to the weight of the organic component .

According to the second aspect of the present invention, a sulfur source, an organic component mainly composed of carbon, moisture, and anaerobic microorganisms capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions coexist. Dissolved dust that determines the amount of addition of dissolved dust to the soil in order to suppress the generation of hydrogen sulfide from the soil containing the organic component, which is placed in an environment where the hydrogen sulfide is easily generated A method for determining the amount of addition,
The soil contains a sulfur source such that the ratio of the sulfur source contained in the soil to the weight of the organic component in the soil is 0.54% by weight or more when the weight of the sulfur source contained therein is measured as the weight of calcium sulfate. And
The dissolved dust does not substantially contain an organic component as a hydrogen sulfide generating component, while containing zinc oxide as a hydrogen sulfide suppressing component,
The dissolved dust addition amount determination method is as follows:
Prior to the addition of the dissolved dust to the soil, a part of the dissolved dust to be added is extracted as a dissolved dust sample, and a part of the soil to which the dissolved dust is to be added is extracted as a soil sample. An extraction process to
The weight Z of the extracted dissolved dust sample, the weight ΔZ of the zinc oxide contained in the dissolved dust sample, the weight X of the extracted soil sample, and contained in the soil sample Measuring step of measuring the weight ΔX of the organic component,
The ratio of the measured value of the zinc oxide weight ΔZ to the measured value of the dissolved dust sample weight Z is expressed as the actual zinc oxide content ratio D (= ΔZ) in which the zinc oxide is actually contained in the dissolved dust. / Z) and the ratio of the measured value of the weight ΔX of the organic component to the measured value of the weight X of the soil sample, the actual organic component containing the organic component actually contained in the soil A calculation step of calculating as a rate A (= ΔX / X);
A setting step of setting a mixed soil weight Y, which is the weight of the portion of the soil that is to be stirred and mixed with the dissolved dust after the dissolved dust is added;
The dissolved dust addition amount ΔY, which is the weight of the dissolved dust to be added to the soil, is obtained by multiplying the actual organic component content A, the mixed soil weight Y, and a predetermined reference value R (= A · Y · R) is compared with the value (= (A · Y · R) / D) divided by the actual zinc oxide content D, and the divided value (= (A · Y · R) / D) or more look including a determination step of determining to have certain numbers,
The reference value R is provided as a method for determining the amount of dissolved dust added, which means the lower limit of the range of the ratio of the weight of the zinc oxide to the weight of the organic component .

  In one specific example, the measuring step removes the organic component from the soil sample by burning the soil sample as an organic component measuring method, and the weight of the soil sample after the burning is calculated. When adopting a combustion removal method for measuring the weight ΔX of organic components contained in the soil sample before combustion as a decrease from the weight, the reference value R is 4% to 6%. When the measurement process adopts a method different from the combustion removal method as the organic component measurement method, the reference value R is compatible with the other method. Thus, it is a value converted from the previously selected numerical value.

  In one specific example, the dissolved dust contains a plurality of components including zinc oxide, and among these components, zinc oxide is contained in a higher ratio than the other components.

  In yet another embodiment, the dissolved dust contains zinc oxide in a proportion in the range of 5% to 85% by weight.

According to the third aspect of the present invention, the hydrogen sulfide is generated because a sulfur source, an organic component, moisture, and an anaerobic microorganism capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions coexist. A method for producing a soil conditioner that is added to soil in order to modify the soil in an easy environment,
The soil conditioner contains a raw material containing gypsum and zinc oxide as an additive,
The method is
Prior to the production of the soil conditioner, an extraction process for extracting a part of the soil to which the soil conditioner is to be added as a sample;
A measurement step of measuring the weight X of the extracted sample and the weight ΔX of the organic component contained in the sample;
The ratio of the measured value of the organic component weight ΔX to the measured value of the sample weight X is defined as the actual organic component content A (= ΔX / X) in which the organic component is actually contained in the sample. A calculation process to calculate,
The ratio of the weight ΔY of the soil conditioner to be added to the soil to the weight Y of the part of the soil that is scheduled to be mixed with the soil conditioner after the addition of the soil conditioner is the target mixing ratio B A setting step for setting as (= ΔY / Y);
A determination step of determining a target zinc oxide content C, which is a target value of the zinc oxide content contained in the soil conditioner, wherein the target zinc oxide content C is determined as the target zinc oxide. The product (= (C / A) · B) of the value (= C / A) obtained by dividing the content rate C by the actual organic component content rate A (= C / A) and the target mixing ratio B is determined to be within a predetermined range. things and,
And a step of adding the zinc oxide to the raw material under the determined target zinc oxide content C and stirring to thereby produce the soil improver. The

  In one specific example, the predetermined range is a range in which 1% is a lower limit value and 21.1% is an upper limit value.

According to a fourth aspect of the present invention, there is provided a method for producing a gypsum board in which a platy core material containing gypsum is coated with a base paper for board on at least one side thereof.
A slurry preparation step of preparing a slurry by mixing pulp fiber raw material, water, starch paste, zinc oxide powder, and sulfuric acid band;
Paper making from the slurry using a paper machine, press dewatering the paper using a press machine, drying the paper using a dryer, thereby completing the paper,
Using the completed paper as the board base paper, and assembling the gypsum board by covering at least one side of the core; and
A content rate determination step executed prior to the slurry preparation step, wherein the zinc oxide content rate is a ratio of the weight of the zinc oxide powder contained in the board base paper to the total weight of the same board base paper A gypsum board manufacturing method is provided that includes: determining a value to be within a predetermined range.

  In one embodiment, the slurry preparation step includes an aqueous system that promotes dispersion of the pulp fiber raw material, the water, the starch paste, the zinc oxide powder, and the zinc oxide powder in the water. The slurry is prepared by mixing with a dispersant.

  In another specific example, the predetermined range is a range in which 0.05% is the lower limit and 1% is the upper limit.

According to a fifth aspect of the present invention, there is provided a gypsum board in which a platy core material containing gypsum is coated with a base paper for board on at least one side thereof,
A gypsum board is provided in which zinc oxide powder is added to at least the back surface of the base paper for board that contacts the front surface of the core material.

  In one specific example, the zinc oxide powder is added only to the back surface of the board base paper without being added to the core material.

In one embodiment, the board base paper, if it does not contain a sulfate band, the board base paper acts substantially as an organic component, while the board base paper is sulfuric acid. In the case of containing a band, the portion of the board base paper excluding the sulfate band substantially acts as an organic component,
The zinc oxide powder is added to the back surface of the board base paper at a ratio of 0.05% or more per 4 cm ^{2 with} respect to the total weight of the board base paper.

  In one specific example, the zinc oxide powder is added to the whole base paper for board without being added to the core material.

In one embodiment, if the board base paper does not contain a sulfate band, the board base paper acts substantially as an organic component, while the board base paper is sulfuric acid. In the case of containing a band, the portion of the board base paper excluding the sulfate band substantially acts as an organic component,
The zinc oxide powder is added to the whole board base paper at a ratio of 1% or more per 4 cm ^{2 with} respect to the total weight of the board base paper.

  In one embodiment, the board base paper contains a sulfate band.

  In one embodiment, the gypsum board as a whole contains a sulfur source at a weight percentage above the saturation region starting point where the hydrogen sulfide generation from the gypsum board begins to saturate.

  According to the sixth aspect of the present invention, there is provided paper made using a slurry prepared by mixing pulp fiber raw material, water, starch paste, zinc oxide powder, and sulfuric acid band. The The paper itself is a hydrogen sulfide source, and at the same time acts as a hydrogen sulfide inhibitor due to the inclusion of zinc oxide.

According to a seventh aspect of the present invention, there is provided a method for producing a gypsum board containing zinc oxide,
A slurry preparation step of mixing a pulp fiber raw material, water, starch paste, zinc oxide powder, and a sulfuric acid band in a container, thereby preparing a slurry;
A paper making process for making paper from the slurry using a paper machine;
A dehydration step of press dewatering the paper using a press;
Using a dryer, drying the press-dehydrated paper, thereby completing a base paper for board of the gypsum board; and
The finished board base paper covers at least one side of the both sides of the core of the gypsum board, thereby assembling the gypsum board, thereby providing a gypsum board manufacturing method.

  According to the present invention, the following embodiments are also obtained. Each aspect is divided into sections, each section is numbered, and is described in the form of quoting the section numbers of other sections as necessary. In this way, each section is referred to the section number of the other section. By describing in the format, the technical features described in each section can be appropriately made independent according to the properties.

(1) It is used in an environment where hydrogen sulfide is likely to be generated due to the coexistence of a sulfur source, an organic component, moisture, and an anaerobic microorganism capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions. A product that suppresses the generation of hydrogen sulfide,
Either or both of the sulfur source and the organic component are provided from the product or another object or both;
The product contains zinc oxide or zinc,
The zinc oxide or zinc content is reached by controlling the generation of hydrogen sulfide by adjusting the ratio of the zinc oxide or zinc to the organic component within a predetermined numerical range. A product determined relative to the target concentration of hydrogen sulfide and the amount of said organic component.

(2) The product according to item (1), wherein the numerical range has a lower limit value of about 0.1% and an upper limit value of about 21%.

(3) The product includes a first structure in which the base paper for board is directly fixed to the core material so that the plate-like core material is covered with the base paper for board on at least one side thereof, or the board A gypsum board having a second structure in which a base paper is bonded to the core by an adhesive;
The core material contains the sulfur source,
The adhesive contains the organic component,
When the gypsum board adopts the first structure, at least one of the core material and the base paper for board contains the zinc oxide or zinc, and the gypsum board adopts the second structure. In the case, the product according to (1) or (2), wherein at least one of the core material, the base paper for board, and the adhesive contains the zinc oxide or zinc.

(4) The product according to (3), wherein the numerical range has a lower limit value of about 0.1% and an upper limit value of about 2%.

(5) The product according to (1) or (2), which is a soil conditioner added to the soil to solidify or granulate the soil to be regenerated.

(6) The product according to (5), wherein the numerical range has a lower limit value of about 1% and an upper limit value of about 21%.

(7) Sulfurization in an environment where hydrogen sulfide is easily generated due to the coexistence of sulfur source, organic components, moisture, and anaerobic microorganisms capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions. A method for suppressing the generation of hydrogen,
Selecting the ratio of zinc oxide or zinc to the organic component as an effect control factor;
By controlling the selected effect control factor, the amount of zinc oxide or zinc is relative to the target concentration of hydrogen sulfide and the amount of organic component to be reached by inhibiting the generation of hydrogen sulfide. A process to determine automatically,
Reacting the determined amount of the zinc oxide or zinc with the sulfur source, the organic component, the moisture and the anaerobic microorganism, thereby inhibiting the generation of the hydrogen sulfide.

(8) Sulfurization in an environment where hydrogen sulfide is easily generated due to the coexistence of sulfur source, organic components, moisture, and anaerobic microorganisms capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions. A method for generating hydrogen while suppressing generation of hydrogen,
A method of reacting zinc oxide or zinc with the sulfur source, the organic component, the moisture and the anaerobic microorganism.

FIG. 1 is a cross-sectional view showing a sewer pipe according to the first embodiment of the present invention. FIG. 2A is a conceptual diagram for explaining a mechanism in which hydrogen sulfide is generated from sewage sludge when a conventional sewage pipe is used, and FIG. 2B is a diagram illustrating sewage sludge when the sewage pipe shown in FIG. 1 is used. It is a conceptual diagram for demonstrating the mechanism in which generation | occurrence | production of hydrogen sulfide is suppressed. FIG. 3 is a cross-sectional view showing a gypsum board according to the second embodiment of the present invention. FIG. 4 shows the hydrogen sulfide generation amount in Experiments 1 to 8 for confirming the hydrogen sulfide generation suppression effect by the sewage pipe shown in FIG. 1, the gypsum board shown in FIG. 3, and the soil conditioner according to the third embodiment of the present invention. It is a figure which shows the experimental instrument for measuring. FIG. 5A is a table for explaining types of zinc oxide used in the plurality of experiments or a material containing the same, and FIG. 5B is a diagram for explaining types of sewage sludge used in the plurality of experiments. It is a table. FIG. 6 is a graph showing the results of Experiment 1. FIG. 7 is a graph showing the results of Experiment 2. FIG. 8 is a graph showing the results of Experiment 3. FIG. 9 is a graph showing the results of Experiment 4. FIG. 10 is a graph showing the results of Experiment 5. FIG. 11 is a graph showing the results of Experiment 6. FIG. 12 is a graph showing the results of Experiment 7. FIG. 13 is a graph showing the results of Experiment 8. FIG. 14 is a graph showing a part of the results of Experiments 6 to 8 in contrast. FIG. 15 is a graph that compares the experimental results supporting the hydrogen sulfide generation suppressing effect of zinc oxide with the experimental results supporting the hydrogen sulfide generation suppressing effect of zinc. FIG. 16 is a process diagram showing a soil improver manufacturing method according to the fifth embodiment of the present invention. FIG. 17 is a cross-sectional view of the soil for explaining how the soil conditioner is added to the soil in order to explain Step S5 shown in FIG. FIG. 18 is a plurality of graphs for explaining a plurality of parameters in step S5 shown in FIG. FIG. 19 is a process diagram showing a soil improvement method according to the sixth embodiment of the present invention. FIG. 20 is a process diagram showing a gypsum board manufacturing method according to the seventh embodiment of the present invention. FIG. 21 is a partially enlarged sectional view showing a gypsum board according to the eighth embodiment of the present invention. FIG. 22 is a graph showing the results of a plurality of types of experiments conducted to consider the optimum method, position, and ratio of adding zinc oxide powder to the base paper for gypsum board shown in FIG. FIG. 23 is another graph showing the results of a plurality of types of experiments conducted to consider the optimum method, position, and ratio of adding zinc oxide powder to the base paper for the gypsum board shown in FIG. FIG. 24 is still another graph showing the results of a plurality of types of experiments conducted in order to consider the optimum method, position and ratio of adding zinc oxide powder to the base paper for gypsum board shown in FIG. FIG. 25 is still another graph showing the results of a plurality of types of experiments conducted in order to consider the optimum method, position and ratio of adding zinc oxide powder to the base paper for gypsum board shown in FIG. FIG. 26 shows a case where the amount of hydrogen sulfide generated from the base paper for board as a sample varies in accordance with the amount of gypsum added to the sample, as in FIG. It is a graph showing the result of that experiment. FIG. 27 is similar to FIG. 26 and is performed to confirm that the amount of hydrogen sulfide generated from the sludge as a sample has a saturation region and changes according to the amount of gypsum added to the sample. It is a table | surface showing the conditions and result of another experiment. FIG. 28 is a graph showing the results of the experiment shown in FIG.

  Hereinafter, some of the more specific embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment of the Present Invention>

  FIG. 1 shows a cross-sectional view of a sewer pipe 10 according to a first exemplary embodiment of the present invention. As is well known, this sewer pipe 10 is buried in the ground and used. The sewage pipe 10 has a pipe wall 12 having a hollow circular cross section, and an inner surface 14 of the pipe wall 12 accommodates a fluid (an example of a hydrogen sulfide generation source) such as sludge and sewage while it is upstream. An inner chamber 16 is defined that allows flow downstream from the interior. The material constituting the tube wall 12 may be cement, synthetic resin, metal, or other similar material.

  When the sewage pipe 10 is in use, sludge is usually stored in the inner chamber 16 in a fluidized state in the lower portion thereof, but may be stored in some cases. The inner surface 14 normally contacts the sludge locally in the circumferential direction, but may also contact the sludge as a whole in the circumferential direction. In addition, when the sewage pipe 10 is buried in the ground, the angle around the center line (for example, which part is buried so as to be directly above) is not normally specified. It is thought that the whole area | region in the circumferential direction is a contact surface with sludge.

  Sludge usually contains a sulfur source and organic components. Here, “sludge” is a broad term and includes a wide range of sludge, for example, wastewater sludge, sewage sludge, livestock manure, and the like.

  In the sludge, there are anaerobic microorganisms (microorganisms that inhabit the natural world) that can generate hydrogen sulfide from sulfur sources under anaerobic conditions. This anaerobic microorganism propagates in the presence of moisture, that is, in a wet state.

Therefore, unless special measures are taken for the sewage pipe 10, harmful hydrogen sulfide (H ₂ S) is generated from the sludge as conceptually shown in FIG. 2A. There are various theories about the mechanism of hydrogen sulfide generation. According to one theory, when anaerobic microorganisms decompose organic components, they take in a sulfur source and generate hydrogen sulfide.

  On the other hand, the sewage pipe 10 according to the present embodiment has a high-purity zinc oxide (ZnO) powder commercially available as an industrial product on the entire inner surface 14, that is, a contact surface with sludge, or cast iron such as a foundry. Dissolved dust (casting dissolution byproduct) discharged from the melting furnace is applied.

  Since the dissolved dust contains zinc oxide, it becomes a supply source of zinc oxide. The dissolved dust is a waste (industrial waste) containing zinc oxide, but attention is paid to the fact that it contains zinc oxide. In this embodiment, the dissolved dust is used as a hydrogen sulfide generation inhibitor. When dissolved dust is used as a hydrogen sulfide generation inhibitor, the dissolved dust is turned into resources, which promotes effective use of resources, and as a result, is more rational than using commercially available high-purity zinc oxide. Is.

  There are various examples of methods for applying the powder to the inner surface 14.

  In one example, a liquid adhesive is first applied on the inner surface 14, thereby forming an adhesive layer on the surface of the inner surface 14. Next, the powder is sprayed onto the surface of the adhesive layer before the adhesive layer is dried. As a result, the powder is exposed on the inner surface 14 of the sewer pipe 10, thereby allowing the powder to come into contact with the sludge accommodated in the sewer pipe 10.

  In another example, the liquid adhesive and the material containing the powder are first mixed, thereby preparing a paint and then applying the paint to the inner surface 14. As a result, the powder is exposed on the inner surface 14 of the sewer pipe 10, thereby allowing the powder to come into contact with the sludge accommodated in the sewer pipe 10. In this case, when the tube wall 12 is made of cement, the liquid adhesive can be made of cement, and when the tube wall 12 is made of synthetic resin, an acrylic resin, It can be composed of a synthetic resin such as a chlorinated resin.

  In yet another example, prior to manufacturing the tube wall 12 with the raw material, the powder is added as an additive to the raw material, and the entire tube wall 12 is manufactured using the added raw material. Thereby, a part of the powder added to the raw material is exposed on the inner surface 14 of the sewer pipe 10, whereby the powder comes into contact with the sludge accommodated in the sewer pipe 10. Is possible.

According to this embodiment, as conceptually shown in FIG. 2B, a reaction occurs in which anaerobic microorganisms act on zinc oxide (ZnO) to generate hydrogen (H ₂ ). Since this reaction is preferentially performed over generation of hydrogen sulfide by anaerobic microorganisms, hydrogen sulfide is apparently absorbed by zinc oxide, and as a result, generation of hydrogen sulfide is suppressed. It is presumed that anaerobic microorganisms (such as sulfate-reducing bacteria) act on the surface of zinc oxide powder to selectively ionize zinc Zn and generate hydrogen gas.

  According to the present embodiment, once the sewage pipe 10 to which zinc oxide is fixed as described above is once installed in the ground, there is no need to replenish the sewage pipe 10 with zinc oxide for a long time thereafter. is there. On the other hand, instead of this method, it is also possible to employ a method of suppressing generation of hydrogen sulfide by directly adding dissolved dust powder to the sludge in the sewage pipe 10. However, in this case, since the dissolved dust does not remain at the same position, it is necessary to add the dissolved dust periodically. Therefore, according to the present embodiment, the labor of the operator is small, and as a result, the total substantial cost is low.

  The sewage pipe 10 is an example of a structure that allows contaminated water to flow or be stored. Other structures of this type include wastewater pits, side grooves (for example, U-shaped grooves). and so on.

<Second Embodiment of the Present Invention>

  FIG. 2 shows a cross-sectional view of a gypsum board 20 according to a second exemplary embodiment of the present invention. The gypsum board 20 is configured such that a plate-like core material 22 is covered with a base paper for board 24 on both sides thereof, and the core material 22 and the base paper for board 24 are bonded to each other by an adhesive layer. Yes. An example of the total thickness of the gypsum board 20 is 9.5 mm.

Since the core material 22 is mainly composed of gypsum (calcium sulfate CaSO ₄ ), the core material 22 contains a sulfur source.

  Since the adhesive layer 26 is composed of starch paste, it contains organic components such as starch, cellulose, paraffin, and wax.

  When the gypsum board 20 is left outdoors as a waste material, it absorbs rainwater and consequently contains moisture. As in the case of the sewage pipe 10, the gypsum board 20 is inhabited by anaerobic microorganisms that can generate hydrogen sulfide from a sulfur source under anaerobic conditions.

  When this gypsum board 20 has been used and converted into waste material (hereinafter referred to as “waste gypsum board”), the waste material is usually crushed by a specific machine into a group of a plurality of gypsum pieces. Landfilled. At this time, each gypsum piece includes a plurality of pieces generated by crushing a part of the base paper 24 for board and a plurality of pieces generated by crushing a part of the adhesive layer 26 attached to the pieces. And a plurality of fragments produced by crushing a part of the core material 22 attached to the fragments are aggregated.

Therefore, if the gypsum board 20 is disposed in a landfill without taking any special measures, harmful hydrogen sulfide (H ₂ S) is generated from the gypsum board 20.

  On the other hand, the gypsum board 20 according to the present embodiment is impregnated or impregnated with zinc oxide (ZnO) powder or dissolved dust powder in at least one of the core material 22, the base paper 24 for board, and the adhesive layer 26. It has been applied. Since the dissolved dust contains zinc oxide (the content ratio can be measured), it becomes a supply source of zinc oxide. In any case, the gypsum board 20 acts as a hydrogen sulfide generation inhibitor at the same time as a hydrogen sulfide generation source.

  In this embodiment, the gypsum board 20 is configured by adhering the board base paper 24 to the surface of the core material 20 with an adhesive so that the core material 22 is covered with the board base paper 24. However, the gypsum board 20 has another structure, for example, a structure in which the board base paper 24 is mechanically fixed directly to the core material 22, that is, a throwing effect between the core material 22 and the board base paper 24. It is also possible to adopt the structure used.

  The method for manufacturing the gypsum board 20 containing zinc oxide in the board base paper 24 will be described in detail later.

<Third embodiment of the present invention>

  Although not shown, the soil conditioner according to the third exemplary embodiment of the present invention is derived from waste material of gypsum board 20 containing zinc oxide (hereinafter referred to as “waste gypsum board”), that is, waste gypsum. This soil conditioner is obtained by baking and drying the dihydrate gypsum powder obtained by pulverizing the waste gypsum board to make hemihydrate gypsum or anhydrous gypsum. Used for solidification and stabilization of sludge and soft ground, and as roadbed material.

  In this soil improver, the gypsum of the core material 22 and the gypsum portion of the board base paper 24 have a property of acting to solidify the soil when added to the soil.

  Since this soil conditioner is derived from the waste gypsum board, it itself acts as a hydrogen sulfide generation inhibitor at the same time as a hydrogen sulfide generation source, like the gypsum board 20. When this soil conditioner is used for soil improvement of field soil such as paddy fields, it is possible to avoid poor growth due to plant root rot due to generation of hydrogen sulfide.

<Experiment to confirm the suppression effect of hydrogen sulfide generation by zinc oxide>

  The present inventors conducted Experiment 1 to Experiment 8 in order to confirm the effect of suppressing hydrogen sulfide generation by the sewer pipe 10 shown in FIG. 1, the gypsum board 20 shown in FIG. 3, and the soil improver.

1. Explanation of experimental equipment (see Fig. 4)

  A plurality of samples (materials) to be mixed were stirred (kneaded) using a mixer (not shown) operating at 26 rpm. Further, the particle diameters of the dissolved dust powder and the zinc oxide powder were measured by a laser method using a laser diffraction particle size measuring device.

  Moreover, in order to measure the content rate of the organic component (organic carbon) in sludge, the combustion type organic carbon measuring method is implemented. In this measurement method, first, a sludge sample in a wet state was collected, and its weight was measured as an initial weight A. Next, the sludge sample was dried by heating at 105 ° C. using an infrared moisture meter (not shown), and the weight B of the sludge sample after the drying was measured. Thereafter, the dried sludge sample was heated at 600 ° C. for 3 hours, thereby burning most of the organic components in the sludge sample and converting it to carbon dioxide. Thereby, almost most of the organic components disappeared from the sludge sample, and in this state, the weight C of the sludge sample was measured.

  Since the value obtained by subtracting the weight C from the weight B is the weight of the organic component in the sludge sample, the content of the organic component in the sludge sample was calculated by dividing the value by the initial weight A. In this specification, for convenience, this measurement method is referred to as a combustion removal method or a combustion removal type organic carbon measurement method.

  This organic carbon measurement method is merely an example of an organic carbon measurement method that can be employed in the present embodiment, and other methods, for example, the amount of carbon dioxide generated by the combustion of a sample is measured, and the sludge is obtained from the measured value. It is possible to measure the amount of organic components (organic carbon) therein.

  Moreover, the sample was administered into the sample container 50, thereby realizing an environment in which hydrogen sulfide gas can be generated from the sample.

  The concentration (ppm) of hydrogen sulfide gas generated from the sample was measured as the amount of hydrogen sulfide generated by the iodine titration method specified in JIS K 0102 39.2. However, this time, in order to measure only hydrogen sulfide gas in the head space in the sample container 50, the work of adding sulfuric acid to the sample and the work of heating were omitted.

  Specifically, as shown in FIG. 4, two impingers 52 and 54 connected in series are connected to the sample container 50, and the zinc acetate solution is administered into each impinger 52 and 54 as an absorbing solution. did.

  In order to establish anaerobic conditions in the sample container 50, argon gas (indicated as “Ar gas” in FIG. 4) is administered into the sample container 50 at a flow rate of 100 mL / min for 15 minutes, thereby The hydrogen sulfide gas generated from the sample in the container 50 was expelled from the sample container 50 into the impingers 52 and 54, and the hydrogen sulfide gas was trapped in the impingers 52 and 54 by the absorbing solution. The concentration of the trapped hydrogen sulfide gas was measured by the iodine titration method.

2. Explanation of the sample used in the experiment (see Fig. 5)

(1) Zinc oxide source: As a zinc oxide source, one type of dissolved dust powder and three types of commercially available high-purity zinc oxides S, M and L were selectively used. . The dissolved dust and the three types of zinc oxides S, M, and L each have the characteristics shown in FIG. 5A.

The dissolved dust used in this experiment is mainly composed of zinc oxide, the content is about 40% by weight, and the sulfur source is about 0.8% by weight (the weight of the sulfur source is equal to the weight of SO ₃ ). Converted). In addition, the melt | dissolution dust considered as the implementation object of this invention contains a zinc oxide in the ratio within the range from 5 weight% to 85 weight%.

(2) Supply source of organic component mainly composed of carbon (organic carbon): As a supply source of organic component, board base paper 24 peeled from the waste gypsum board (board base paper 24 is after peeling, 3 types of sewage sludges A, B, and C were selectively used, respectively.

  The board base paper 24 is composed entirely of paper (acting as an organic component) and does not contain gypsum (acting as a sulfur source) before being attached to the core member 22. However, since the board base paper 24 used in this experiment was obtained by peeling off the waste gypsum board, the side of the board base paper 24 that was attached to the core member 22 was the side of the board base paper 24. The gypsum which is one component of the core material 22 has adhered to the back surface. Therefore, the board base paper 24 used in this experiment, excluding zinc oxide, contained 95% by weight of paper (acting as an organic component) and 5% by weight of gypsum (acting as a sulfur source).

  In this experiment, in the board base paper 24, it is practically possible to regard the paper as a whole as an organic component and the plaster as a source of sulfur. Therefore, in the board base paper 24, the weight of the organic component can be practically measured as the weight of the paper, and similarly, the weight of the sulfur source can be practically measured as the weight of the gypsum. It is.

  Each of the three types of sewage sludges A, B, and C has the characteristics shown in FIG. 5B.

(3) Sulfur source: As the sulfur source, sewage sludge (hereinafter simply referred to as “sludge”) A, B and C contained in itself, and gypsum pieces were used for the waste gypsum board. The gypsum piece was obtained by taking out only gypsum from the waste gypsum board, and formed a lump, and each gypsum piece had a diameter of about 3 to about 10 mm.

(4) Moisture: As the moisture, moisture contained in the sludges A, B and C was added, and 130 ml of pure water was added to the waste gypsum board.

(5) Anaerobic microorganism: In order to add anaerobic microorganisms, an aqueous solution containing anaerobic microorganisms was added.

3. Specific contents of various experiments

(1) Experiment 1 (Comparative Example 1)

  The purpose of the experiment: To know the relationship between the amount of sulfur source and the amount of hydrogen sulfide generated without adding zinc oxide.

  Experimental Method: Gypsum pieces (sulfur source) were added in variable addition amounts to base paper 24 for board having a constant weight (30 g) (because it is a source of organic components and sulfur source because it is a gypsum paper). A sample (mixture) obtained by adding gypsum pieces to the board base paper 24 was stirred for 60 seconds using a mixer. After stirring, the concentration (ppm) of the generated hydrogen sulfide (the higher the amount generated, the higher the concentration) was measured as a physical quantity reflecting the amount of hydrogen sulfide generated for each added amount of gypsum pieces.

  Results of experiment: As shown in the graph of FIG. 6, the hydrogen sulfide generation amount (ppm) is at least within the range where the ratio of the amount of gypsum piece added to the amount of the base paper for board 24 is from 5 wt% to 50 wt% Was confirmed to be almost constant even when the amount of gypsum piece added changed.

  Findings: The amount of hydrogen sulfide generated is almost independent of the amount of sulfur source.

  To further support this finding, the Applicant conducted two additional experiments.

First additional experiment

1. Experimental conditions

  Four types of samples are prepared. In these samples, 200 ml of pure water and 1 ml of hydrogen sulfide generating seeds (sulfate-reducing bacteria) are added to the base paper for board 24 containing organic components (starch, etc.). These components were put into a container (500 mL capacity) for each sample. Thereafter, the sample in the container was stirred. For all samples, the board base paper 24 had a thickness of 180 μm, a size of 1 cm × 1 cm, and a weight of 1.7 g.

  In these samples, calcium sulfate dihydrate (special grade reagent, Kanto Chemical Co., Inc.) was added as a sulfur source in different amounts. Specifically, the weight percent of the sulfur source addition amount with respect to the base paper for board 24 is 0.17% for the first sample, 0.29% for the second sample, and for the third sample, 1.37% and for the fourth sample was 6.07%.

  After the sample was prepared, dissolved oxygen was removed from the sample in the container, and all the gas in the head space in the container was replaced with nitrogen. The container was then closed.

  The samples were allowed to stand for 80 days in a temperature-controlled room set at 35 ° C. Hydrogen sulfide generated from each sample during the experiment is confined in the head space in the corresponding container. As a result, the larger the volume of generated hydrogen sulfide, the higher the concentration of the hydrogen sulfide. Therefore, it means that the higher the concentration of hydrogen sulfide, the more hydrogen sulfide is generated.

  After culturing for 80 days, the concentration (ppm) of hydrogen sulfide existing in the head space of each container was measured as a physical quantity reflecting the amount of hydrogen sulfide generated.

2. results of the experiment

FIG. 26 is a graph showing the measurement results of the amount of hydrogen sulfide generated. In this graph, the ratio (%) of the weight of the sulfur source (represented by “gypsum weight” in FIG. 26) to the weight of the base paper 24 for board (represented by “paper weight” in FIG. 26) is plotted on the horizontal axis. Has been taken. Here, “gypsum weight” means the weight of the sulfur source, but was measured not as the weight of the sulfur atom S but as the weight of calcium sulfate CaSO ₄ . This is because a situation where a sulfur atom exists as a compound called calcium sulfate constituting the main component of gypsum is assumed, not a situation where a sulfur atom exists alone.

  As described above, in the graph of FIG. 26, the ratio (%) is plotted on the horizontal axis. However, in this experiment, the weight of the board base paper 24 is constant throughout. Therefore, the graph of FIG. 26 substantially represents the relationship between the gypsum weight (amount of sulfur source) and the amount of hydrogen sulfide generated.

  According to the graph of FIG. 26, the hydrogen sulfide generation amount increases as the amount of the sulfur source increases until the ratio reaches 0.29%. However, when the ratio reaches 0.29%, thereafter, even if the amount of sulfur source increases, the amount of hydrogen sulfide generated does not increase.

  Thus, when the sample is the base paper for board 24, when the amount of sulfur source reaches a certain value between the amount of sulfur source and the amount of hydrogen sulfide generated, the amount of hydrogen sulfide generated is saturated, and thereafter There is a relationship that the amount of hydrogen sulfide generated does not increase even if the amount of sulfur source increases.

  Therefore, when the condition that the amount of the sulfur source is equal to or greater than a specific value is satisfied, the amount of hydrogen sulfide generated does not depend on the amount of the sulfur source and is constant. Therefore, the numerical value of 0.29% means the saturation region start point of the hydrogen sulfide generation amount when the board base paper 24 is a hydrogen sulfide generation source.

  During the experiment, the pH of each sample was 6.4.

Second additional experiment

1. The purpose of the experiment

  The same experiment as FIG. 26 was performed on the sludge (sewage sludge) as a sample. This experiment was conducted to confirm whether the amount of hydrogen sulfide generated from the sludge is saturated with the increase in the amount of sulfur source when the sludge is a hydrogen sulfide source.

2. Characteristics of the sample used

The sludge as a sample contained an organic component, but the sulfur source contained only a very small amount. Therefore, the sulfur source as a whole sample was substantially only gypsum added to the sludge (sometimes referred to as “CaSO ₄ ” for convenience).

  However, when gypsum acts as a hydrogen sulfide generator, the action of gypsum does not change between when gypsum is originally contained in sludge and when gypsum is added to sludge. The difference between whether the gypsum used in the experiment was originally present in the sludge or later added to the sludge does not affect the results of this experiment.

3. Composition of sludge used (sewage sludge)

(1) Moisture content: 72.0% by weight (measured using an infrared moisture meter)

(2) Organic component content: 6.0% by weight (measured using the aforementioned combustion removal method in which sludge is heated at 600 ° C. for 3 hours)

(3) Content of sulfur source: 0.01% by weight (measured using a fluorescent X-ray analyzer)

When this sulfur source content is converted to the CaSO ₄ content (multiplied by the molecular weight ratio between the two), it is 0.04 wt%. Hereinafter, for convenience of explanation, the weight of the sulfur source was all measured as a converted value to the weight of CaSO ₄ .

4). Sample preparation

  As shown in FIG. 27, four types of samples are prepared, and these samples commonly include sand (containing no organic component or sulfur source), starch (an added organic component), and 250 ml of pure water. Then, 1 ml of a hydrogen sulfide-producing inoculum (sulfuric acid-reducing bacteria) was added, and these components were put into a container (500 mL capacity) for each sample. Thereafter, the sample in the container was stirred.

  In each sample, dry sand was added, which intentionally created a situation where the sulfur source content in each sample was less than the sulfur source content in normal sludge, This is for confirming how hydrogen sulfide is generated over a wide range in which the content of the sulfur source varies.

  In this experiment, as described above, since organic components were originally present in the sludge, it was not indispensable to intentionally add organic components to generate hydrogen sulfide. However, in order to ensure that the content of the original organic component does not become insufficient in order to reliably achieve the purpose of this experiment, starch as a supplemental organic component is converted into an organic component in the sludge. It added to.

5. Sample composition

(1) Sample 1: Sludge was not contained, and a sulfur source (CaSO ₄ ) was not added, but 1.30 g of starch (an organic component for supplementation) was added. As a result, the weight ratio of the sulfur source to the total organic components (this time only starch) in the sample 1 was 0%. The sulfur source added was calcium sulfate dihydrate (reagent special grade, Kanto Chemical Co., Inc.) for the other samples as well.

(2) Sample 2: Since 5.00 g of sludge and 95.00 g of sand were contained, and the sulfur source (CaSO ₄ ) was not added to the sludge, the total sulfur source of sample 2 was 0.002 g (this time Was the only sulfur source in the sludge), and the added starch was 1.00 g. As a result, the weight ratio of the sulfur source to the total organic components in Sample 2 (both organic components in sludge 0.30 g and added starch 1.00 g) was 0.15%.

(3) Sample 3: Since 5.00 g of sludge and 95.00 g of sand were contained, and the added sulfur source (CaSO ₄ ) was 0.005 g, the total sulfur source of sample 3 was 0.007 g. And the added starch was 1.00 g. As a result, the weight ratio of the sulfur source relative to the total organic components in Sample 3 (both 0.30 g of organic components in sludge and 1.00 g of added starch) was 0.54%.

(4) Sample 4: Since 5.00 g of sludge and 95.00 g of sand were contained, and the added sulfur source (CaSO ₄ ) was 0.02 g, the total sulfur source of Sample 4 was 0.022 g. And the added starch was 1.00 g. As a result, the weight ratio of the sulfur source to the total organic components in Sample 4 (both 0.30 g of organic components in sludge and 1.00 g of added starch) was 1.69%.

6). Experimentation

  After the sample was prepared, dissolved oxygen was removed from the sample in the container, and all the gas in the head space in the container was replaced with nitrogen. The container was then closed. The four samples were allowed to stand for 10 days in a temperature-controlled room set at 35 ° C. After culturing for 10 days, the concentration (ppm) of hydrogen sulfide existing in the head space of each container was measured as a physical quantity reflecting the amount of hydrogen sulfide generated.

7). results of the experiment

FIG. 27 is a table, and FIG. 28 is a graph showing the measurement results of the amount of hydrogen sulfide generated. In the graph of FIG. 28, the weight of the sulfur source (represented by “sulfur weight (converted to CaSO ₄ )” in FIG. 28) with respect to the weight of the total organic component (represented by “organic component weight” in FIG. 28). Ratio (%) is taken on the horizontal axis. However, in this experiment, the weight of the whole organic component is constant throughout. Therefore, the graph of FIG. 28 substantially represents the relationship between the sulfur weight (amount of sulfur source) and the amount of hydrogen sulfide generated.

  According to the graph of FIG. 28, the amount of hydrogen sulfide generated increases as the amount of sulfur source increases until the ratio reaches 0.54%. However, when the ratio reaches 0.54%, the amount of hydrogen sulfide generated does not increase thereafter even if the amount of sulfur source increases.

  Thus, even when the sample is sludge, when the amount of sulfur source reaches a certain value between the amount of sulfur source and the amount of hydrogen sulfide generated, the amount of hydrogen sulfide generated is saturated. There is a relationship that even if the amount of sulfur source increases, the amount of hydrogen sulfide generated does not increase.

  Therefore, when the condition that the amount of the sulfur source is equal to or greater than a specific value is satisfied, the amount of hydrogen sulfide generated does not depend on the amount of the sulfur source and is constant. Therefore, the numerical value of 0.54% means a saturation region start point of the amount of hydrogen sulfide generated from the sludge when the sludge is a hydrogen sulfide generation source.

  During the experiment, the pH of each sample was 6.5.

(2) Experiment 2 (Comparative Example 2)

  The purpose of the experiment: To know the relationship between the amount of organic matter and the amount of hydrogen sulfide generated without adding zinc oxide.

  Experimental method: Sludge having a constant weight (100 g) (source of organic components) was selected in order from the above-mentioned three types of sludges A, B and C having different organic component ratios. Each sludge A, B, C was stirred for 60 seconds using a mixer. After stirring, the amount of hydrogen sulfide generated was measured for each type of sludge A, B and C.

  Results of experiment: As shown in the graph of FIG. 7, it was confirmed that the amount of hydrogen sulfide generated increased almost proportionally to the amount of organic matter.

  Findings: The amount of hydrogen sulfide generated depends on the amount of organic matter, and there is a direct proportional correlation between the two.

(3) Experiment 3 (Example 1)

  Purpose of experiment: When the hydrogen sulfide generation source is sludge A and the hydrogen sulfide generation inhibitor is dissolved dust (containing zinc oxide), the ratio of the amount of zinc oxide to the amount of organic matter (hereinafter, Know the relationship (hereinafter also referred to as “hydrogen sulfide generation amount curve”) between “zinc oxide / organic matter ratio (%)” and hydrogen sulfide generation amount. Furthermore, the degree to which the hydrogen sulfide generation amount curve depends on the degree to which the dissolved dust powder is dispersed in the sludge A (hereinafter referred to as “dispersion degree”) is known.

  In this experiment 3, as in other experiments 6, 7, and 8 described later, the hydrogen sulfide generation source is sludge A, and the hydrogen sulfide generation inhibitor is dissolved dust (containing zinc oxide). The situation simulates the use situation of the sewage pipe 10 to which the dissolved dust powder or zinc oxide is applied, or the soil conditioner to which the dissolved dust powder or zinc oxide is added. Therefore, the result of this experiment 3 represents the performance of the sewer pipe 10 and the soil conditioner.

  In addition, when the soil improving agent is the board base paper 24, the board base paper 24 also contains a sulfur source, but even if the sulfur source is added to the sludge A accordingly. Since the sulfur source content in the sludge A exceeds the saturation region start point shown in FIG. 27, the amount of hydrogen sulfide generated does not increase.

  Method of experiment: Sludge A shown in FIG. 5B (the weight used is constant over a plurality of experiments belonging to Experiment 3 and is 100 g. The organic content ratio is 9.5% by weight). The content was 40%) with variable addition amount, and the hydrogen sulfide generation amount was measured for each addition amount.

  In the sludge A, the weight content of the organic component is 9.5% in any experiment. Therefore, the weight of the organic component in the sludge A is multiplied by the measured value of the sludge A by 9.5%. Was measured by

  Similarly, since the zinc oxide content in the dissolved dust powder is 40%, the weight of zinc oxide in the dissolved dust powder is obtained by multiplying the measured value of the weight of the dissolved dust powder by 40%. Was measured by

  Two sets of experiments were performed, and in the first set of experiments, a mixture obtained by adding dissolved dust powder to sludge A was stirred for 20 seconds using a mixer, while in the two sets of experiments, The mixture was stirred for 180 seconds using a mixer. It is expected that the dispersibility of the dissolved dust powder is lower in the mixture used in the first set of experiments than in the mixture used in the second set of experiments.

  In each set of experiments, in order to change the zinc oxide / organic matter ratio, the addition amount (g) of the dissolved dust powder was set to “0”, “0.3”, “0.5”, “1. It was changed in order to “0”, “1.5”, “2.0” and “5.0”.

The dissolved dust contains not only ZnO that can be isolated, but also a complex metal oxide that can be expressed by a formula of (Fe, Zn, Mn) _x O _y . Although the value obtained by converting the fluorescent X-ray measurement value into an oxide does not exactly match the amount of zinc oxide, there is no difference in practically observing both, so the fluorescent X-ray measurement value of dissolved dust is It was adopted as the amount of zinc oxide in dissolved dust.

  Results of experiment: As shown in the graph of FIG. 8, the dissolved dust has an effect of suppressing the generation of hydrogen sulfide such that if the zinc oxide / organic matter ratio increases with respect to the sludge A, the amount of generated hydrogen sulfide decreases accordingly. Have

  In addition, when the zinc oxide / organic matter ratio is 1.3%, the amount of hydrogen sulfide generated is reduced by about 50% than when no dissolved dust is added, and when the zinc oxide / organic matter ratio is 2.1%, it is reduced by about 65%. In addition, it decreases by about 80% at 4.2%, decreases by about 89% at 6.3%, decreases by about 90% at 8.4%, and 21.1 %, A 100% decrease was confirmed.

  It was also confirmed that the higher the dispersibility of the dissolved dust powder, the greater the effect of suppressing the generation of hydrogen sulfide than the lower one, but the difference between the two is not so significant.

  Findings: When the source of hydrogen sulfide is sludge, use dissolved dust so that the lower limit of the allowable numerical range of the zinc oxide / organic matter ratio is about 1%, or about 2%. Or about 6% is preferable from the viewpoint of securing the effect of suppressing the generation of hydrogen sulfide.

  As described above, as shown in FIG. 7, it was confirmed that the amount of hydrogen sulfide generated increased substantially in proportion to the amount of organic matter.

  On the other hand, as shown in FIG. 8, the hydrogen sulfide generation amount curve is a downward convex curve as a whole, and for each part, it first decreases with a large gradient as the zinc oxide / organic matter ratio increases from zero. Thereafter, the gradient becomes gentle, and eventually the gradient becomes almost horizontal.

  That is, the graph of FIG. 8 differs from the graph of FIG. 7 in that the gradient of the graph is remarkably different between the lower region and the upper region of the variable range taken on the horizontal axis. An inflection point exists in the middle of the two areas.

  In view of this characteristic, the lower limit of the allowable numerical range of the zinc oxide / organic matter ratio is, for example, the first half steep decrease region (sensitive zone) and the second half metastable region (slow gradient reduction region, insensitive zone or semi-dead zone). A zinc oxide / organic ratio value corresponding to the inflection point between and about 4% and about 6%, for example, is desirable.

  Each of these lower limit values can be combined with any of the plurality of upper limit values described below.

  In addition, when the hydrogen sulfide generation source is sludge, the dissolved dust is used so that the upper limit value of the allowable numerical range of the zinc oxide / organic matter ratio is about 20% or about 8%. It is desirable from the viewpoint of preventing use of dissolved dust. Each of these upper limit values can be combined with any of the plurality of lower limit values described above.

(4) Experiment 4 (Example 2)

  Objective of the experiment: The hydrogen sulfide generation source is board base paper 24 (gypsum paper. However, as will be described later, for convenience of experiment, it does not contain zinc oxide), and the hydrogen sulfide generation inhibitor is dissolved dust (zinc oxide). The relationship between the zinc oxide / organic matter ratio (%) and the amount of hydrogen sulfide generated is known. Furthermore, the degree to which the relationship depends on the degree of dispersion of the dissolved dust powder is known.

  In this experiment 4, like the other experiment 5 described later, the board base paper 24 itself does not contain zinc oxide and is added for the convenience of the experiment to change the zinc oxide content relatively freely. Dissolved dust whose amount can be controlled relatively freely supplies zinc oxide.

  In this experiment 4, as in other experiments 5 described later, the hydrogen sulfide generation source is board base paper 24 (does not contain zinc oxide), and the hydrogen sulfide generation inhibitor is dissolved dust (containing zinc oxide). The experimental situation is to simulate the use situation of the base paper for board 24 to which dissolved dust powder or zinc oxide is added. Therefore, the result of Experiment 4 represents the performance of the base paper 24 for board.

  Method of experiment: The base paper for board 24 (the weight used is constant 30 g throughout a plurality of experiments belonging to Experiment 3), the dissolved dust powder (zinc oxide content 40% by weight) shown in FIG. It added by the variable addition amount like the case, and the hydrogen sulfide generation amount was measured for every addition amount.

  In the base paper for board 24 (however, for convenience of experiment, zinc oxide is not included), the content of the paper is 95% by weight in any of the experiments. Therefore, the weight of the organic component in the base paper for board 24 is It was measured by multiplying the measured value of the weight of the board base paper 24 by 95%.

  Similarly, in the dissolved dust powder, since the zinc oxide content is 40% by weight, the weight of zinc oxide in the dissolved dust powder is 40% of the measured value of the weight of the dissolved dust powder. Measured by multiplication.

  Experimental results: As shown in the graph of FIG. 9, the dissolved dust generates hydrogen sulfide as the amount of hydrogen sulfide generated decreases as the zinc oxide / organic matter ratio increases with respect to the base paper 24 for board. Has a suppressive effect.

  In addition, when the zinc oxide / organic matter ratio is 0.1%, the amount of hydrogen sulfide generated is reduced by about 40% than when no dissolved dust is added, and when it is 0.2%, it is reduced by about 50%. In addition, when it is 0.4%, it decreases by about 65%, when it is 0.6%, it decreases by about 75%, when it is 0.8%, it decreases by about 80%, %, A 100% decrease was confirmed.

  It was also confirmed that the higher the degree of dispersion of the dissolved dust powder, the greater the effect of suppressing the generation of hydrogen sulfide than the lower one, but the difference between the two is not so significant.

  Knowledge: When the hydrogen sulfide generation source is the base paper 24 for board, the dissolved dust is used so that the lower limit of the allowable numerical range of the zinc oxide / organic matter ratio is about 0.1%, or about 0.2 From the viewpoint of ensuring the effect of suppressing the generation of hydrogen sulfide, it is desirable to use it so that it is approximately 0.4%.

  As shown in FIG. 9, the hydrogen sulfide generation amount curve is a downward convex curve as a whole, and for each part, it first decreases with a large gradient as the zinc oxide / organic matter ratio increases from 0, and thereafter, It has a characteristic that the gradient becomes gentle and eventually the gradient becomes almost horizontal. In view of this characteristic, the lower limit value of the allowable numerical range of the zinc oxide / organic matter ratio is, for example, the value of the zinc oxide / organic matter ratio corresponding to the inflection point between the first large gradient region and the next small gradient region. For example, about 0.2%, or a value of the zinc oxide / organic matter ratio corresponding to the inflection point between the small gradient region and the next quasi-horizontal region, for example, about 0.8%. Is possible.

  Each of these lower limit values can be combined with any of the plurality of upper limit values described below.

  Further, when the hydrogen sulfide generation source is the base paper 24 for board, the dissolved dust is used so that the upper limit value of the allowable numerical range of the zinc oxide / organic matter ratio is about 2%, or about 1%. It is desirable from the viewpoint of preventing wasteful use of dissolved dust. Each of these upper limit values can be combined with any of the plurality of lower limit values described above.

(5) Experiment 5 (Example 3)

  Purpose of experiment: When the hydrogen sulfide generation source is board base paper 24 (gypsum paper, does not contain zinc oxide), and the hydrogen sulfide generation inhibitor is a commercially available zinc oxide powder (ie, commercially available). The relationship between the zinc oxide / organic matter ratio (%) and the amount of hydrogen sulfide generated is known in the case of simulating the use of the gypsum board 20 to which the zinc oxide powder is added. Specifically, it is confirmed that even when a commercially available zinc oxide powder is used instead of the dissolved dust powder, it has an effect of suppressing hydrogen sulfide generation. Furthermore, the degree to which the hydrogen sulfide generation amount curve depends on the degree of dispersion of the zinc oxide powder is known.

  Experimental Method: An experiment similar to Experiment 4 was performed using a commercially available zinc oxide powder M (particle size D50, particle size 0.79 μm) instead of dissolved dust powder.

  Results of experiment: As shown in the graph of FIG. 10, even when a commercially available zinc oxide powder was used, it was confirmed that it had an effect of suppressing hydrogen sulfide generation in the same manner as the dissolved dust powder. In addition, the commercially available zinc oxide powder has an effect of suppressing hydrogen sulfide generation when the zinc oxide / organic matter ratio is 0.1% or more with respect to the base paper 24 for board. For the first time, it was confirmed that the hydrogen sulfide generation amount became zero and the hydrogen sulfide generation suppression effect was maximized.

  It was also confirmed that the higher the degree of dispersion of the zinc oxide powder, the greater the effect of suppressing the generation of hydrogen sulfide than the lower one, but the difference between the two is not so significant.

  Knowledge: When the hydrogen sulfide generation source is the base paper for board 24, the commercially available zinc oxide powder may be used within the range of the zinc oxide / organic matter ratio of 0.1% to 2.1%. This is desirable from the viewpoint of the effect of suppressing hydrogen sulfide generation.

(6) Experiment 6 (Example 4)

  Purpose of experiment: When the hydrogen sulfide generation source is sludge and the hydrogen sulfide generation inhibitor is a commercially available zinc oxide powder (that is, a sewage pipe 10 to which a commercially available zinc oxide powder is added, In addition, the relationship existing between the zinc oxide / organic matter ratio (%) and the amount of hydrogen sulfide generated is known in the case of simulating the use situation of the soil improver to which commercially available zinc oxide powder is added. Specifically, even when a commercially available zinc oxide powder is used for sludge instead of the base paper for board 24 (gypsum paper), the commercially available zinc oxide powder is used for the base paper for board 24 (gypsum paper). It is confirmed that it has the effect of suppressing hydrogen sulfide generation as in the case of). Furthermore, the degree to which the hydrogen sulfide generation amount curve depends on the degree of dispersion of the zinc oxide powder is known.

  Method of experiment: An experiment similar to Experiment 5 was carried out by replacing the base paper for board 24 (gypsum paper) with sludge A using commercially available zinc oxide powder S (particle size D50, particle size 0.47 μm). Done using.

  Results of experiment: As shown in the graph of FIG. 11, even when the commercially available zinc oxide powder is used for sludge, the effect of suppressing the generation of hydrogen sulfide is the same as in the case of the base paper for board 24 (gypsum paper). It was confirmed to have In addition, commercially available zinc oxide powder has an effect of suppressing the generation of hydrogen sulfide if the zinc oxide / organic matter ratio is 1.1% or more with respect to sludge, and only when it is 21.1%, It was also confirmed that the amount of hydrogen sulfide generation was zero and the effect of suppressing hydrogen sulfide generation was maximized.

  It was also confirmed that the higher the degree of dispersion of the zinc oxide powder, the greater the effect of suppressing the generation of hydrogen sulfide than the lower one, but the difference between the two is not so significant.

  Findings: When the source of hydrogen sulfide is sludge, commercially available zinc oxide powder can be used in a state where the zinc oxide / organic matter ratio is 1.1% or more and 21.1% or less. It is desirable from the viewpoint of suppressing the generation of hydrogen.

  Further, in view of the characteristics of the graph shown in FIG. 11, the lower limit value of the allowable numerical range of the zinc oxide / organic matter ratio is, for example, the first-half steep slope decreasing region (sensitive band) and the second-half metastable region (slow slope decreasing region). The zinc oxide / organic matter ratio corresponding to the inflection point between the insensitive zone and the insensitive zone, for example, a value in the range of about 4% and about 6%.

(7) Experiment 7 (Example 5)

  Purpose of experiment: When the hydrogen sulfide generation source is sludge and the hydrogen sulfide generation inhibitor is a commercially available zinc oxide powder, the ratio between the zinc oxide / organic matter ratio (%) and the amount of hydrogen sulfide generated To know the degree to which the relationship existing in each depends on the particle size and the degree of dispersion of the zinc oxide powder.

  Experimental method: An experiment similar to that in Experiment 6 was carried out. The zinc oxide powder used was changed from zinc oxide S (particle size D50, particle size 0.47 μm) to zinc oxide M (particle size D50, particle size 0.79 μm). I went to. In Experiment 7, the particle diameter of the zinc oxide powder to be used was made larger than that in Experiment 6.

  Results of the experiment: As shown in the graph of FIG. 12, the commercially available zinc oxide powder has the same effect of suppressing the generation of hydrogen sulfide even when the particle size thereof is larger than that in the case of Experiment 6. confirmed. It was also confirmed that the higher the degree of dispersion of the zinc oxide powder, the greater the effect of suppressing the generation of hydrogen sulfide than the lower one, but the difference between the two is not so significant.

  Findings: The relationship that exists between the zinc oxide / organic matter ratio (%) and the amount of hydrogen sulfide generated is less dependent on the particle size of the zinc oxide powder and on the degree of dispersion of the zinc oxide powder.

(8) Experiment 8 (Example 6)

  Purpose of experiment: When the hydrogen sulfide generation source is sludge and the hydrogen sulfide generation inhibitor is a commercially available zinc oxide powder, the ratio between the zinc oxide / organic matter ratio (%) and the amount of hydrogen sulfide generated To know the degree to which the relationship existing in each depends on the particle size and the degree of dispersion of the zinc oxide powder.

  Experimental method: An experiment similar to that in Experiment 7 was carried out. The zinc oxide powder used was changed from zinc oxide M (particle size D50, particle size 0.79 μm) to zinc oxide L (particle size D50, particle size 4.14 μm). Changed from to. In Experiment 7, the particle diameter of the zinc oxide powder to be used was made larger than that in Experiment 7.

  Results of experiment: As shown in the graph of FIG. 13, the commercially available zinc oxide powder has the same effect of suppressing the generation of hydrogen sulfide even when the particle size of the powder is larger than that of Experiment 7. confirmed. It was also confirmed that the higher the degree of dispersion of the zinc oxide powder, the greater the effect of suppressing the generation of hydrogen sulfide than the lower one, but the difference is not so significant.

  Findings: The relationship that exists between the zinc oxide / organic matter ratio (%) and the amount of hydrogen sulfide generated is less dependent on the particle size of the zinc oxide powder and on the degree of dispersion of the zinc oxide powder.

  In view of the characteristics of the graph shown in FIG. 13, the lower limit value of the allowable numerical range of the zinc oxide / organic matter ratio is, for example, the first half steep slope decreasing region (sensitive band) and the second half metastable region (slow slope decreasing region). The zinc oxide / organic matter ratio corresponding to the inflection point between the insensitive zone and the insensitive zone, for example, a value in the range of about 4% and about 6%.

  FIG. 14 is a hydrogen sulfide generation amount curve (curve representing the relationship between the hydrogen sulfide generation amount and the zinc oxide / organic matter ratio) obtained by each of Experiments 6, 7 and 8. What is 180 seconds is represented on the same graph. It is clear from this that the hydrogen sulfide curve is hardly dependent on the particle size of the zinc oxide powder.

  As described above, the effect of suppressing the generation of hydrogen sulfide by zinc oxide has been described with reference to some experimental results. However, it is easily assumed that even when zinc is used instead of zinc oxide, the effect of suppressing the generation of hydrogen sulfide is equivalent. Is done.

  FIG. 15 is a graph showing experimental results supporting the effect of suppressing the generation of hydrogen sulfide by zinc oxide and experimental results supporting the effect of suppressing the generation of hydrogen sulfide by zinc. As is clear from this graph, it is understood that both zinc oxide and zinc (metal zinc) have an effect of suppressing hydrogen sulfide generation. According to this graph, the concentration of generated hydrogen sulfide is almost equal in a situation where the addition rates of zinc oxide and zinc to the same kind of organic matter are different from each other.

  Therefore, the appropriate range of the ratio of the zinc content of the product that suppresses the generation of hydrogen sulfide by zinc to the amount of organic matter that the zinc reacts with is the zinc oxide content of the product that suppresses the generation of hydrogen sulfide by zinc oxide. It may seem that the amount is in the proper range of the ratio of the zinc oxide to the amount of organics to which it reacts and is not consistent with that derived from the above-mentioned experimental results.

  However, the present inventors also added an experiment for testing the effect of suppressing hydrogen sulfide by adding zinc oxide to an organic substance, and an experiment for testing an effect of suppressing hydrogen sulfide by adding zinc to an organic substance. It was confirmed that zinc was dissolved in the aqueous solution collected after the end of the experiment. This means that zinc is used as an intermediate regardless of whether zinc oxide is used or zinc is used. Therefore, it is easily inferred that the mechanism for suppressing hydrogen sulfide generation is the same regardless of whether zinc oxide is used or zinc is used. As a result, the hydrogen sulfide generation amount curves are also easily shared by each other. Inferred.

  Therefore, the appropriate range of the ratio of the zinc content of a product that suppresses the generation of hydrogen sulfide by zinc to the amount of organic matter that the zinc reacts with is the zinc oxide content of the product that suppresses the generation of hydrogen sulfide by zinc oxide. It is easily inferred that the amount corresponds to an appropriate range of ratios relative to the amount of organics with which the zinc oxide reacts.

<Fourth embodiment of the present invention>

  Next, a method for suppressing hydrogen sulfide generation according to the fourth embodiment of the present invention will be described.

  In order to obtain the effect of suppressing the generation of hydrogen sulfide using the sewer pipe 10 shown in FIG. 1, the gypsum board 20 shown in FIG. 3, and the soil improver, the following method is carried out. In an environment where the hydrogen sulfide is likely to be generated due to the coexistence of a sulfur source, an organic component, moisture, and an anaerobic microorganism capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions, This is a method for suppressing the generation of hydrogen sulfide.

  This method includes the step of (a) selecting a ratio of zinc oxide to the organic component as an effect control factor (the aforementioned zinc oxide / organic matter ratio). This step is also a step of defining an effect control factor for controlling the degree of the effect of suppressing the generation of hydrogen sulfide using zinc oxide.

  The method further includes (b) controlling the selected effect control factor to reduce the amount of the zinc oxide to the target concentration of the hydrogen sulfide (the effect of suppressing the generation of hydrogen sulfide using the zinc oxide). Reflecting the degree of its effect, such that the higher the degree is, the lower the effect is) and the relative determination of the amount of the organic component. Here, the “target concentration of hydrogen sulfide” is the target concentration of hydrogen sulfide that should be reached by suppressing the generation of hydrogen sulfide using zinc oxide.

  The method further comprises (c) reacting the determined amount of the zinc oxide with the sulfur source, the organic component, the moisture and the anaerobic microorganism, thereby inhibiting the generation of the hydrogen sulfide. And a step of generating hydrogen.

  In addition, when suppressing generation | occurrence | production of hydrogen sulfide using the gypsum board 20 shown in FIG. 3 and the said soil improvement agent, these gypsum board 20 and a soil improvement agent are embed | buried in or added to soil, Even so, the soil does not have fluidity to the gypsum board 20 and the soil conditioner and is stationary. Accordingly, it is possible to measure the weight of the portion of the soil that comes into contact with the gypsum board 20 and the soil conditioner, and thus the “amount of organic component” can also be measured.

  On the other hand, in the case of the sewage pipe 10 shown in FIG. 1, it may seem that the “amount of organic component” cannot be measured because the sewage sludge in contact therewith has fluidity. However, if the average value of the area of the inner surface 14 of the sewage pipe 10 in contact with the sewage sludge is statistically known, the average value of the amount of sewage sludge that instantaneously contacts the inner surface 14 is also statistically known. The amount of the “organic component” can be measured using the amount.

<Fifth embodiment of the present invention>

  In FIG. 16, the soil improvement agent manufacturing method according to 5th Embodiment of this invention is shown with process drawing.

  Briefly described, this method for producing a soil conditioner is produced by adding the above-described soil conditioner, which is an example of a product that suppresses the generation of hydrogen sulfide by zinc oxide, without excess or deficiency as much as possible. It is a specific example of the method to do.

  In the environment where the hydrogen sulfide is easily generated because the soil improver coexists with a sulfur source, organic components, moisture, and anaerobic microorganisms capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions. It is added to soil to modify it. This soil conditioner contains a raw material containing gypsum (for example, a substance called gypsum itself or a substance containing gypsum like waste gypsum board) and zinc oxide as an additive.

  The target soil in the present embodiment contains a sulfur source at a weight% that is equal to or higher than the saturation region start point at which the amount of hydrogen sulfide generated from the soil begins to saturate. Therefore, when determining the amount of zinc oxide to be added to the soil in order to suppress the generation of hydrogen sulfide from the soil, the content of the sulfur source in the soil can be ignored.

  Furthermore, the soil which becomes object in this embodiment also contains the organic component which has carbon as a main component.

  By the way, “soil” in the present specification is produced by the biological action of fine crushing substances and plant remains (organic matter) that are weathered products of rocks. On the other hand, “sludge” in the present specification is a mud-like waste having intermediate properties between solid and liquid, and is generated not only in the production activities of the mining industry and agricultural / fishery industry, but also in sewage and sewage treatment. It occurs from various environments such as pollution prevention facilities such as wastewater treatment.

  In order to examine the relationship between each defined soil and sludge, there is a generation process in which sludge is generated as the final material when soil is used as a starting material and moisture and other components are added to it. To do. If attention is paid to this, as long as the soil contains the sulfur source and the organic component, the sludge naturally contains the sulfur source and the organic component. Therefore, if attention is paid to the above-described generation process and the presence of a sulfur source and an organic component as common components, sludge is considered to belong to soil.

  Therefore, “soil” in this specification includes those that belong to “sludge” and those that do not belong, but in any case, as long as the soil contains organic components and a sulfur source, The above-mentioned several experimental results hold similarly.

  Moreover, even if the soil conditioner which is the object in this embodiment does not contain any organic component or contains it at all, it is a trace amount, and even if the organic component is added to the soil, It is assumed that it does not affect the amount of hydrogen sulfide generated. The case where the amount of the organic component contained in the soil conditioner is not trace and the amount of hydrogen sulfide generated from the soil may increase when the organic component is added to the soil will be described later.

  In this soil conditioner, gypsum has the property of acting to solidify the soil when added to the soil (including the aforementioned sludge). In addition, in this soil conditioner, zinc oxide acts to suppress generation of hydrogen sulfide that may be generated from the soil because the soil conditioner contains gypsum and is added to the soil. It has the property to do.

  FIG. 16 is a process diagram showing this soil improver manufacturing method.

  In this soil improver manufacturing method, first, extraction process S1 is performed prior to manufacture of the soil improver which is the target product. In this extraction step S1, a part of the soil (sludge as a lot) to which the soil improver is to be added is extracted as a soil sample. The extracted soil sample is stored and stored in a container, for example, by an operator.

  This soil sampling can be performed multiple times for the same target area or the same mass within the same target area. In that case, first, a plurality of soil samples are collected. As for the soil samples, for example, by using a method called reduction, it is possible to prepare a single representative sample as a result.

  Next, measurement process S2 is performed. In this measurement step S2, the weight X of the extracted soil sample is measured by using a weight measuring device, and the weight ΔX of the organic component contained in the soil sample is further determined as the sludge described above. It is measured by the combustion removal method in the same manner as in the case of measuring the content of the organic component therein.

  Then, calculation process S3 is performed. In this calculation step S3, the ratio of the measured value of the organic component weight ΔX to the measured value of the soil sample weight X is such that the organic component content A (where the organic component is actually contained in the soil sample). = ΔX / X).

  Thereafter, the setting step S4 is executed. In this setting step S4, as shown schematically in FIG. 17, the weight of the soil conditioner ΔY to be added to the soil is mixed with the soil conditioner after the addition of the soil conditioner in the soil. The ratio of the planned portion (soil to be improved) to the weight Y is set as the target mixing ratio B (= ΔY / Y).

  Subsequently, the determination step S5 is performed. In this determination process S5, the target zinc oxide content rate C which is the target value of the zinc oxide content rate in which zinc oxide is contained in the soil conditioner is determined.

  Here, the relationship between the target zinc oxide content C, the actual organic component content A, the amount of added soil improvement agent ΔY, and the weight Y of the soil to be improved will be briefly described with reference to the graph of FIG. The weight (total weight) P of zinc oxide in the total amount of the soil conditioner to be added increases as the target zinc oxide content C increases, and as the amount of added soil conditioner ΔY increases. Therefore, the total weight P of zinc oxide is proportional to the product of the target zinc oxide content C and the addition amount ΔY of the soil conditioner.

  In addition, the weight (total weight) Q of the organic component in the entire soil to be improved mixed with the soil improver to be added increases as the actual organic component content A increases, and the weight Y of the soil to be improved increases. The more it is, the more it is. Therefore, the total weight Q of the organic component is proportional to the product of the actual organic component content A and the weight Y of the soil to be improved.

  Against the background described above, in step S5 shown in FIG. 16, when the reference value (lower limit value of the appropriate numerical range) predetermined for the zinc oxide / organic component ratio is represented by R, the target zinc oxide content C Is determined to be equal to or greater than the value of A · R / B.

  An example of the reference value R is a numerical value within the range of 4% and 6% (for example, 5%). Here, an example of the reference value R is set based on the results of the experiments 3, 6, 7, and 8 described above.

  Then, manufacturing process S6 is performed. In this production step S5, zinc oxide is added as an additive to the raw material of the soil conditioner (for example, gypsum, waste gypsum board, etc.) based on the determined target zinc oxide content C, and stirred. As a result, a soil conditioner is completed.

  The soil improver thus produced is transported to the site, where it is added by the operator to the surface of the soil at a target addition density.

  In the present embodiment, the soil conditioner contains gypsum and zinc oxide, but does not contain any organic components or has a composition containing only a trace amount. Therefore, it is possible to determine the target zinc oxide content C, completely ignoring the amount of organic components contained in the soil conditioner.

  On the other hand, in the case where the soil conditioner contains organic components in a non-trace amount in addition to gypsum and zinc oxide, for example, it is desirable to change the above-described method for producing a soil conditioner as follows. .

  That is, the extraction step S1 further includes a step of obtaining a soil improvement agent sample, and the measurement step S2 is further included in the weight S of the soil improvement agent sample and the soil improvement agent sample. A step of measuring the weight ΔS of the organic component.

  In addition, the calculation step S3 further calculates the ratio of the measured value of the organic component weight ΔS to the measured value of the weight S of the soil conditioner sample, in which the organic component is actually contained in the soil conditioner sample. And calculating the organic component content E (= ΔS / S).

  By the way, in this example, the total weight P of zinc oxide is proportional to the product of the target zinc oxide content C and the addition amount ΔY of the soil improver, as in the above-described embodiment, but the soil improvement to be added The weight (total weight) Q of the organic component in the soil to be improved mixed with the agent is different from the above-described embodiment, and the weight of the actual organic component in the soil, that is, the actual organic component content A and the improvement It is proportional to the product of the weight Y of the planned soil and the weight of the actual organic component in the soil improver, that is, the product of the actual organic component content E and the added amount ΔY.

  Therefore, in this example, the determination step S5 determines the target zinc oxide content C to be equal to or greater than the value of (A · R / B + E · R).

  In any example, the soil conditioner can be added to the soil by various methods. For example, the soil conditioner is added to the soil, and the soil surface layer is stirred after the addition, This soil conditioner can be introduced into a plurality of holes formed in the soil surface layer.

As is clear from the above description, according to this embodiment, when it is necessary to add zinc oxide to the soil conditioner so that the soil conditioner has a hydrogen sulfide suppression effect, It is possible to determine the amount of addition without excess or deficiency in consideration of the weight of the organic component in the soil (in some cases, also in consideration of the weight of the organic component in the soil improver).
<Sixth Embodiment of the Present Invention>

  FIG. 19 is a process diagram showing a soil improvement method according to the sixth embodiment of the present invention.

  In this soil improvement method, the sulfur source, the organic component, the moisture, and the anaerobic microorganism capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions coexist, so that the hydrogen sulfide is easily generated. This is a method for modifying soil by adding dissolved dust to a certain soil (including the aforementioned sludge). The dissolved dust contains zinc oxide but does not contain an organic component.

  The target soil in the present embodiment contains a sulfur source at a weight% that is equal to or higher than the saturation region start point at which the amount of hydrogen sulfide generated from the soil begins to saturate. Therefore, when determining the amount of zinc oxide to be added to the soil in order to suppress the generation of hydrogen sulfide from the soil, the content of the sulfur source in the soil can be ignored.

  In this soil improvement method, first, extraction process S51 is performed prior to the addition of dissolved dust to the soil. In this extraction step S51, a part of the dissolved dust is extracted as a dissolved dust sample, and a part of the soil to which the dissolved dust is to be added is extracted as a soil sample.

  Next, a measurement process is performed in step S52. In this measurement step S52, the weight Z of the extracted dissolved dust sample, the weight ΔZ of zinc oxide contained in the dissolved dust sample, the weight X of the extracted soil sample, and The weight ΔX of the organic component contained in the soil sample is measured. The weight ΔZ of zinc oxide contained in the dissolved dust sample is measured using, for example, an X-ray fluorescence analyzer as described above, and the weight ΔX of the organic component contained in the soil sample is used. Is measured by the combustion removal method described above.

  Subsequently, in step S53, a calculation process is performed. In this calculation step S53, the ratio of the measured value of the zinc oxide weight ΔZ to the measured value of the dissolved dust sample weight Z in the same manner as in step S3 shown in FIG. The ratio of the measured value of the organic component weight ΔX to the measured value of the weight X of the soil sample is calculated as the actual zinc oxide content D (= ΔZ / Z) contained in the The actual organic component content A (= ΔX / X) actually contained in

  Thereafter, a setting step is performed in step S54. In the setting step S54, the mixed soil weight Y of a portion (soil to be improved) scheduled to be mixed with the dissolved dust after the addition of the dissolved dust is set in the soil.

  By the way, in this embodiment, the total weight P of zinc oxide is proportional to the product of the actual zinc oxide content D and the addition amount ΔY of the soil improver, but is planned to be mixed with the added soil improver. The weight (total weight) Q of the organic component in the entire soil is proportional to the weight of the actual organic component in the soil, that is, the product of the actual organic component content A and the weight Y of the soil to be improved.

  Subsequently, a determination process is performed in step S55. In this determination step S55, the target dissolved dust addition amount ΔY, which is the weight of the dissolved dust to be added to the soil, is determined to be equal to or greater than the value of ((A · Y · R) / D).

  In the measurement step S52, the organic component to be measured is removed from the soil sample by burning the soil sample as an organic component measurement method, and the weight of the soil sample after combustion is calculated from the weight of the soil sample before combustion. When adopting a method (combustion removal method) that measures the weight ΔX of the organic components contained in the soil sample as the decrease, the reference value R is preselected within the range of 4% to 6%. Number.

  On the other hand, when the measurement step S52 employs another method as an organic component measurement method (for example, a combustion extraction method that measures the organic component content from carbon dioxide generated by combustion of a soil sample), a reference value is used. R is a value converted from the previously selected numerical value so as to conform to the other method.

  By the way, if the organic component content rate is measured by the combustion removal method for a certain soil sample and then the organic component content rate is measured by another method for the same soil sample, a measured value different from the first measured value is obtained. there is a possibility. However, these two measurement values are the measurement results for the same soil sample, although the measurement methods employed are different, and, regardless of which measurement method is employed, the soil sample is caused by combustion. Since no chemical reaction other than a chemical reaction occurs, a certain correlation is established between the two measured values.

  Regardless of the type of the other method, as long as the reference value R when the combustion removal method is adopted is unambiguous, the reference value R when the other method is adopted is also unambiguously, and It will be decided in advance.

  Thereafter, in step S56, a spraying process is executed. In the spraying step S56, the dissolved dust is sprayed on the soil based on the determined target dissolved dust addition amount ΔY, and then the sprayed dissolved dust is mixed with the soil.

  As is clear from the above description, according to this embodiment, when it is necessary to suppress the generation of hydrogen sulfide from the soil using dissolved dust containing zinc oxide as a hydrogen sulfide inhibitor, the oxidation is performed. It is possible to determine the weight of dissolved dust to be added to the soil without excess or deficiency so that the amount of zinc added to the soil is appropriate in relation to the weight of the organic component in the soil.

  The method according to the present embodiment is a method for determining the amount of dissolved dust that is an example of a hydrogen sulfide inhibitor containing zinc oxide at a ratio of less than 100% by weight, but this method requires a necessary change. In addition, it can be used to determine the amount of addition of a hydrogen sulfide inhibitor containing only zinc oxide, i.e., the amount of addition when adding zinc oxide to the soil as a hydrogen sulfide inhibitor. is there.

  In the specific example, the above-described method for determining the amount of dissolved dust added is changed as follows.

  In the extraction step S51, a part of soil to which zinc oxide is to be added is extracted as a soil sample. Since zinc oxide is a hydrogen sulfide inhibitor whose actual zinc oxide content is known to be 1, it is not necessary to obtain a sample of zinc oxide.

  In the measurement step S52, the weight X of the extracted soil sample and the weight ΔX of the organic component contained in the soil sample are measured.

  In the calculation step S53, the ratio of the measured value of the organic component weight ΔX to the measured value of the soil sample weight X is the actual organic component content ratio A (= ΔX / X).

  In the setting step S54, the mixed soil weight Y of the portion (soil to be improved) to be mixed with the zinc oxide after the addition of zinc oxide is set in the soil.

  In the determination step S55, it is determined that the target zinc oxide addition amount ΔY, which is the weight of zinc oxide to be added to the soil, is equal to or greater than the value of (A · Y · R). Here, (A · Y · R) is derived by substituting 1 into the actual zinc oxide content D in the above-mentioned ((A · Y · R) / D).

In the spraying step S56, zinc oxide is added to the soil based on the determined target zinc oxide addition amount ΔY.

<Seventh embodiment of the present invention>

  FIG. 20 is a process diagram showing a gypsum board manufacturing method according to the seventh embodiment of the present invention.

  Briefly described, this gypsum board manufacturing method oxidizes gypsum board 20 (containing zinc oxide in this description), which is an example of a product that suppresses the generation of hydrogen sulfide by zinc oxide. It is an example of the method of manufacturing by adding zinc as much as possible without excess and deficiency.

  FIG. 20 is a process diagram showing this gypsum board manufacturing method. As shown in FIG. 3, the gypsum board 20 manufactured by this gypsum board manufacturing method is configured by covering a platy core material 22 containing gypsum with board base paper 24 on both sides thereof. However, this gypsum board manufacturing method can also be applied to manufacture a gypsum board in which the core material 22 is coated with the base paper 24 for board only on one side.

  As shown in FIG. 20, in this gypsum board manufacturing method, first, the content rate determining step S101 is executed, which will be described later.

  Next, slurry preparation process S102 is performed. In the slurry preparation step S102, the pulp fiber raw material, water, starch paste, zinc oxide powder, sulfuric acid band, and necessary additives are mixed in a container (not shown), whereby the slurry Is prepared. Here, the sulfuric acid band is an example of a cationic compound, and acts to promote fixing of zinc oxide powder as inorganic particles to the pulp fiber material.

  Subsequently, the paper making process S103 is performed. In the paper making step S103, paper is made from the slurry using a paper machine (not shown, but having, for example, a bat and a mesh wire). The paper (wet paper) is then press dehydrated using a press (not shown, but has a press roll, for example). The paper is then dried using a dryer (not shown, but has, for example, a rotating drum dryer). Thus, the paper is completed.

  Thereafter, the assembly step S104 is executed. In the assembling step S104, the finished paper is used as the base paper for board 24 to cover both surfaces of the core material 22, whereby the gypsum board 20 is assembled.

  Here, the content rate determining step S101 will be described. In the content rate determining step S101, the ratio of the weight of the zinc oxide powder contained in the board base paper 24 to the total weight of the same board base paper 24 is shown. The zinc oxide content rate (weight ratio of zinc oxide added to the base paper for board 24) is determined to be within a predetermined range.

  An example of the predetermined range is a range in which 0.05% is the lower limit and 1% is the upper limit. Here, an example of the predetermined range is set based on a plurality of experimental results shown in FIGS. 22 and 23 described later.

  Therefore, in the slurry preparation step S102 subsequent to the content rate determination step S101, the zinc oxide powder is mixed with, for example, pulp fiber material, water and starch paste under the determined zinc oxide content rate. To be added.

  In one specific example, in the slurry preparation step S102, the pulp fiber raw material, the water, the starch paste, the zinc oxide powder, the sulfate band, and the zinc oxide powder are dispersed in the water. The slurry is prepared by mixing an aqueous dispersant that facilitates this and the necessary additives.

  In addition, although the manufacturing method according to this embodiment is implemented in order to manufacture the kind of paper called the board base paper 24 for the gypsum board 20, it can also be implemented in order to manufacture other kinds of paper. .

<Eighth Embodiment of the Present Invention>

  FIG. 21 shows a partially enlarged cross-sectional view of a gypsum board according to an eighth embodiment of the present invention. However, since this embodiment has many elements in common with the second embodiment shown in FIG. 3, common elements are referred to by using the same reference numerals or names, and redundant description is omitted, and different elements. Only will be described in detail.

  As described above, in the gypsum board 20 according to the second embodiment, at least one of the core material 22, the board base paper 24, and the adhesive layer 26 is made of zinc oxide (ZnO) powder or the dissolved dust powder ( Hereinafter, it is simply referred to as “zinc oxide powder”).

  On the other hand, in the gypsum board 100 according to this embodiment, as shown in FIG. 21, the zinc oxide powder is applied only on the base paper 24 for board.

  Specifically, prior to the board base paper 24 being mounted on the core material 22, the front surface (surface that does not contact the core material 22) 24a and the back surface 24b (surface that contacts the core material 22) of the board base paper 24, Among them, the zinc oxide layer 110 coated with zinc oxide powder is formed only on the back surface 24b by, for example, coating means such as brushing or spraying. In other words, the board base paper 24 is coated with the zinc oxide powder only on one side thereof. For example, when brushing is employed, first, zinc oxide powder is dispersed in the starch paste, and then the starch paste is brushed on the surface of one side of the base paper 24 for board.

  When the board base paper 24 is coated with zinc oxide powder on only one side thereof, the board base paper 24 is adhered to both sides of the core material 22 with an adhesive 26 or other attachment means (for example, mechanical fasteners). ) To complete the gypsum board 100.

1. Addition of zinc oxide powder to board base paper 24

  According to the study by the present inventors, the following has been found regarding the method of adding zinc oxide powder to the base paper 24 for board.

1-1. Classification of the method of adding zinc oxide powder to board base paper 24

(1) Impregnation method for impregnating the entire board base paper 24 with zinc oxide powder (2) Application method for applying the zinc oxide powder only to at least one side of the board base paper 24

1-2. Classification of application methods

(1) Double-sided coating method in which zinc oxide powder is applied to both sides of board base paper 24 (2) Single-sided coating method in which zinc oxide powder is applied only to one side of board base paper 24

1-3. Classification of single-sided coating methods

(1) Surface coating method applied only to the front surface 24a of the board base paper 24 (2) Back surface coating method applied only to the back surface 24b of the board base paper 24

  Based on this premise, the present inventors realize that, among these methods, the amount of zinc oxide added to the base paper 24 for board is minimal, but the effect of suppressing hydrogen sulfide by the zinc oxide is maximized. In order to pursue things, the following experiments were conducted.

2. Explanation of the sample used in the experiment

(1) Zinc oxide supply source: The above-described high-concentration commercially available zinc oxide, and the average particle diameter was classified as D50 (0.79 μm).

(2) Board base paper 24: In the experiment, a plurality of board base papers 24 having different zinc oxide addition conditions were used. However, these board base papers 24 were common in thickness and density. Specifically, common to all board base papers 24, the paper thickness is 180 μm, and the paper density (apparent specific gravity, tension) is 1.1 g / cm ³ , The basis weight of the paper was 0.020 g / cm ² . Further, since each board base paper 24 used in the experiment is not attached and peeled off from the core material 22, it does not contain gypsum transferred from the core material 22, but contains a sulfuric acid band as a sulfur source.

(3) Organic component supply source: Paper portion of base paper 24 for board

  The board base paper 24, excluding zinc oxide, contained 98% by weight of paper (acting as an organic component) and 2% by weight of sulfuric acid band (acting as a sulfur source).

(4) Core material 22: In the experiment, a plurality of core materials 22 having the same material characteristics (for example, gypsum content) were used.

(5) Source of sulfur source: gypsum in core material 22 and sulfuric acid band in base paper 24 for board

(6) Gypsum board: A plurality of gypsum boards 100 in which a plurality of types of board base papers 24 having different zinc oxide addition conditions are respectively mounted on both surfaces of a plurality of common core materials 22 are used in the experiment. It was.

(7) Moisture: pure water

(8) Anaerobic microorganisms: Anaerobic microorganisms present in the air in the laboratory where this experiment was conducted

3. Test piece, laboratory instrument and experiment method

(1) Test piece

  Each of the plurality of gypsum boards 100 having different zinc oxide addition conditions was cut into a plurality of 2 cm × 2 cm test pieces.

(2) Laboratory equipment

  Twenty-five test pieces (one set of test pieces) having the same zinc oxide addition conditions were put together into a 500 ml capacity bottle, and 200 ml of pure water was injected into the bottle. . Thereby, 25 test pieces were completely submerged in the bottle.

(3) Experimental method

  One set of test pieces was left for 40 days or more in a submerged state in the bottle under an environmental temperature of 35 ° C. During the standing period, the amount (concentration) of hydrogen sulfide generated from the bottle was measured a plurality of times using the measuring instrument shown in FIG.

4). Specific contents of various test piece sets

(1) First test piece set (indicated by “no zinc oxide” in Comparative Example 1, FIG. 22 and FIG. 23): Same as the gypsum board 100 except that no zinc oxide is added. Corresponds to normal gypsum board.

(2) Second test piece set (Experimental Example 1, indicated by “Zinc oxide 0.1%” in FIG. 22 and also indicated by “Total” in FIG. 24): Zinc oxide is present on the entire board base paper 24 100 gypsum board added by impregnation at a weight ratio of 0.1%

(3) Third test piece set (indicated as “Zinc oxide 0.3%” in Experimental Example 2 and FIG. 22): Zinc oxide is added to the whole board base paper 24 by impregnation at a weight ratio of 0.3%. Plasterboard 100

(4) Fourth test piece set (Experimental Example 3, indicated as “Zinc Oxide 0.5%” in FIG. 22 and also indicated as “Overall” in FIG. 25): Zinc oxide is present on the entire board base paper 24 100 gypsum board added by impregnation at a weight ratio of 0.5%

(5) Fifth test piece set (shown as “Zinc oxide 1%” in Experimental Example 4 and FIG. 22): Gypsum board 100 in which zinc oxide is added to the whole board base paper 24 by impregnation at a weight ratio of 1%.

(6) Sixth test piece set (indicated as “0.05% zinc oxide” in Experimental Example 5 and FIG. 22): Zinc oxide is applied only on the back surface 24b of the board base paper 24 at a weight ratio of 0.05%. Added gypsum board 100

(7) Seventh test piece set (Experimental Example 6, indicated by “Zinc Oxide 0.1%” in FIG. 22 and also indicated by “Back Side” in FIG. 24): Zinc oxide is the back side of board base paper 24 Gypsum board 100 added by coating at a weight ratio of 0.1% only to 24b

(8) Eighth test piece set (Experimental Example 7, indicated by “rear surface” in FIG. 25): Gypsum board in which zinc oxide is added to only the rear surface 24b of the base paper 24 for board at a weight ratio of 0.5%. 100

(9) Ninth test piece set (indicated as “surface” in Experimental Example 8 and FIG. 24): Gypsum in which zinc oxide is added only to the surface 24a of the board base paper 24 at a weight ratio of 0.1% Board 100

(10) Tenth test piece set (Experimental Example 9, indicated as “surface” in FIG. 25): Gypsum board in which zinc oxide is added to only the surface 24a of the board base paper 24 at a weight ratio of 0.5% 100

5. Consideration on experimental results

  From the plurality of graphs shown in FIG. 22, it is understood that when the impregnation method is adopted, it is desirable that the zinc oxide addition rate is 0.1% or more. From these graphs, when the impregnation method is employed, the amount of hydrogen sulfide generated from the gypsum board 100 is maintained at 0 even if the gypsum board 100 is left for a long period of time if the zinc oxide addition rate is 1% or more. I understand that From this, it is understood that when the impregnation method is adopted, it is desirable that the zinc oxide addition rate is 1% or more.

  Further, it can be seen from the plurality of graphs shown in FIG. 23 that when the back surface coating method is adopted, it is desirable that the zinc oxide addition rate is 0.05% or more.

  Further, from the plurality of graphs shown in FIG. 24, when the zinc oxide addition rate is 0.1%, the maximum hydrogen sulfide suppression effect can be obtained with a small zinc oxide addition amount if the back coating method is adopted. I understand. Also, from the plurality of graphs shown in FIG. 25, even when the zinc oxide addition rate is 0.5%, the maximum hydrogen sulfide suppression effect can be obtained with a small zinc oxide addition amount if the back coating method is adopted. I understand.

  In any case, from FIG. 24 and FIG. 25, when the back coating method is adopted, the hydrogen sulfide suppression effect obtained by the same amount of zinc oxide addition is higher than when the front coating method or the impregnation method is operated. I understand that.

  24 and 25, it can be seen that even when the back coating method is adopted, the amount of hydrogen sulfide generated slightly increases as the standing period elapses. Considering this reason, since the base paper for board 24 originally contains a sulfuric acid band that acts as a sulfur source, not only the core material 22 but also the board base paper 24 has a sulfur source. It is thought that it functioned as a hydrogen sulfide generation source.

  However, even though the board base paper 24 itself functions as a hydrogen sulfide generation source in this way, if the backside coating method is employed, the impregnation method is employed rather than the surface coating method. It can also be seen that the effect of suppressing hydrogen sulfide obtained with the same amount of zinc oxide added is high.

6). Specific configuration of gypsum board 100

  Against the background of some of the above findings, in the present embodiment, the gypsum board 100 is configured to adopt a back surface coating method and the zinc oxide addition rate is 0.05% or more, and is more desirable. Is configured such that the zinc oxide addition rate is 0.1% or more.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and those skilled in the art, including the aspects described in the above [Summary of Invention] section, may be used. It is possible to implement the present invention in other forms in which various modifications and improvements are made based on the knowledge.

Claims (3)

Since the sulfur source, the organic component mainly composed of carbon, moisture, and anaerobic microorganisms capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions coexist, the environment is likely to generate hydrogen sulfide. Sulfurization to determine the amount of addition of a hydrogen sulfide inhibitor containing zinc oxide to the soil in order to suppress the generation of hydrogen sulfide from the soil containing the organic component A method for determining the amount of hydrogen inhibitor added,
The soil contains a sulfur source such that the ratio of the sulfur source contained in the soil to the weight of the organic component in the soil is 0.54% by weight or more when the weight of the sulfur source contained therein is measured as the weight of calcium sulfate. And
The hydrogen sulfide inhibitor contains substantially no organic component as a hydrogen sulfide generating component, while containing zinc oxide as a hydrogen sulfide suppressing component,
The method for determining the amount of hydrogen sulfide inhibitor added is as follows:
Prior to the addition of the hydrogen sulfide inhibitor to the soil, an extraction step of extracting a part of the soil to which the hydrogen sulfide inhibitor is to be added as a soil sample;
A measuring step of measuring the weight X of the extracted soil sample and the weight ΔX of the organic component contained in the soil sample;
The ratio of the measured value of the weight ΔX of the organic component to the measured value of the weight X of the soil sample is expressed as the actual organic component content A (= ΔX / X) in which the organic component is actually contained in the soil sample . ) As a calculation process,
A setting step of setting a mixed soil weight Y that is the weight of a portion of the soil that is to be stirred and mixed with the hydrogen sulfide inhibitor after the hydrogen sulfide inhibitor is added;
The hydrogen sulfide inhibitor addition amount ΔY, which is the weight of the hydrogen sulfide inhibitor to be added to the soil, is the product of the actual organic component content A, the mixed soil weight Y, and a predetermined reference value R. (= A · Y · R) divided by the actual zinc oxide content D (= ΔZ / Z) in which the zinc oxide is actually contained in the hydrogen sulfide inhibitor (= (A · Y · R) R) / D) and determining to have a numerical value equal to or greater than the divided value (= (A · Y · R) / D) ,
The reference value R is a method for determining a hydrogen sulfide inhibitor addition amount, which means a lower limit of a range of a ratio of the weight of the zinc oxide to the weight of the organic component . Since the sulfur source, the organic component mainly composed of carbon, moisture, and anaerobic microorganisms capable of generating hydrogen sulfide from the sulfur source under anaerobic conditions coexist, the environment is likely to generate hydrogen sulfide. A method for determining the amount of dissolved dust added to determine the amount of additive to add dissolved dust to the soil in order to suppress the generation of hydrogen sulfide from the soil containing the organic component,
The soil contains a sulfur source such that the ratio of the sulfur source contained in the soil to the weight of the organic component in the soil is 0.54% by weight or more when the weight of the sulfur source contained therein is measured as the weight of calcium sulfate. And
The dissolved dust does not substantially contain an organic component as a hydrogen sulfide generating component, while containing zinc oxide as a hydrogen sulfide suppressing component,
The dissolved dust addition amount determination method is as follows:
Prior to the addition of the dissolved dust to the soil, a part of the dissolved dust to be added is extracted as a dissolved dust sample, and a part of the soil to which the dissolved dust is to be added is extracted as a soil sample. An extraction process to
The weight Z of the extracted dissolved dust sample, the weight ΔZ of the zinc oxide contained in the dissolved dust sample, the weight X of the extracted soil sample, and contained in the soil sample Measuring step of measuring the weight ΔX of the organic component,
The ratio of the measured value of the zinc oxide weight ΔZ to the measured value of the dissolved dust sample weight Z is expressed as the actual zinc oxide content ratio D (= ΔZ) in which the zinc oxide is actually contained in the dissolved dust. / Z) and the ratio of the measured value of the weight ΔX of the organic component to the measured value of the weight X of the soil sample, the actual organic component containing the organic component actually contained in the soil A calculation step of calculating as a rate A (= ΔX / X);
A setting step of setting a mixed soil weight Y, which is the weight of the portion of the soil that is to be stirred and mixed with the dissolved dust after the dissolved dust is added;
The dissolved dust addition amount ΔY, which is the weight of the dissolved dust to be added to the soil, is obtained by multiplying the actual organic component content A, the mixed soil weight Y, and a predetermined reference value R (= A · Y · R) is compared with the value (= (A · Y · R) / D) divided by the actual zinc oxide content D, and the divided value (= (A · Y · R) / D) or more look including a determination step of determining to have certain numbers,
The reference value R means a lower limit value of a range of the ratio of the weight of the zinc oxide to the weight of the organic component .   The said dissolved dust contains the several component containing the said zinc oxide, The dissolved dust addition amount determination method of Claim 2 which contains the said zinc oxide in a ratio higher than another component among those components.