Method for producing carbonated sludge water, device for producing carbonated sludge water, and method for producing mortar or concrete

Abstract

A method for producing carbonated sludge water according to the present disclosure comprises: obtaining sludge water that contains carbon dioxide by blowing a gas which contains carbon dioxide into sludge water; and obtaining carbonated sludge water by passing the obtained sludge water that contains carbon dioxide through a reactor configured to be able to generate fine bubbles, wherein the reactor is provided with a cylindrical member inside which a flow path is formed and a plurality of protruding members which are provided so as to protrude inward from the inner peripheral surface of the cylindrical member.

Description

Carbonated sludge water manufacturing method, carbonated sludge water manufacturing device, and mortar or concrete manufacturing method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from Japanese Patent Application No. 2024-054516, the disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a method for producing carbonated sludge water, an apparatus for producing carbonated sludge water, and a method for producing mortar or concrete.

[0003] At ready-mix concrete plants, concrete product plants, construction sites, etc., washing wastewater containing aggregate is generated when transport vehicles, mixer trucks, etc. The water from which the aggregate is separated and recovered from the washing wastewater is separated into supernatant water containing calcium ions and the like eluted from cement, and sludge water containing sludge solids, the majority of which are hydration products such as calcium hydroxide and calcium silicate hydrate.

[0004] Sludge water can be reused as mixing water for concrete. However, sludge solids contained in sludge water solidify due to a hydration reaction between the water and the sludge solids contained in the sludge water, making it difficult to store for long periods of time. For this reason, most sludge water is separated into water and sludge solids using a filter press or other device before being disposed of.

[0005] In recent years, one method for effectively utilizing sludge water has been investigated, which involves injecting carbon dioxide into the sludge water and reacting the calcium oxide contained in the sludge water with the carbon dioxide to produce calcium carbonate, thereby carbonated the sludge water. The carbonated sludge water obtained by this method (hereinafter referred to as carbonated sludge water) is not only reused as mixing water for concrete, but also attempts have been made to separate the carbonated sludge water into calcium carbonate, the hydration product, and water, and reuse the resulting calcium carbonate as a material for, for example, agricultural products such as fertilizer, industrial products such as paper, and building materials.

[0006] As a method for producing carbonated sludge water, for example, Patent Document 1 discloses a method of blowing carbon dioxide into sludge water, and more specifically describes blowing carbon dioxide by simple bubbling, as well as by bubbling with stirring and by bubbling with ultrasonic irradiation. Also, Patent Document 2 discloses a method of precipitating calcium carbonate from sludge liquid using a precipitation reaction apparatus formed in a sealed atmospheric pressure vessel.

[0007] In recent years, growing awareness of environmental issues has led to a demand for reducing carbon dioxide emissions into the atmosphere. However, for example, in the method described in Patent Document 1, the injected carbon dioxide does not react sufficiently with calcium oxide in the sludge water, and a large amount of carbon dioxide may be released into the atmosphere.

[0008] Furthermore, for example, in the method described in Patent Document 2, even if a precipitation reaction apparatus is formed in a sealed atmospheric pressure vessel, the atmospheric pressure vessel must be provided with an agitator, a carbon dioxide inlet, and the like, and therefore it is difficult to completely seal the inside of such an atmospheric pressure vessel, and as a result, there is a risk that a large amount of carbon dioxide supplied into the main body of the precipitation reaction apparatus will be released into the atmosphere.

[0009] Japanese Patent Publication No. 2020-163821 Japanese Patent Publication No. 2009-279552

[0010] The present disclosure has been made in consideration of the above circumstances, and aims to provide a method for producing carbonated sludge water that can easily reduce the release of carbon dioxide into the atmosphere, a carbonated sludge water production apparatus used in the production method, and a method for producing mortar or concrete that uses carbonated sludge water obtained using the production method as a material.

[0011] SUMMARY OF THE INVENTION The following presents a brief summary of the disclosure in order to provide a basic understanding of some aspects of the disclosure. This summary is not an overview of the scope of the disclosure. It is not intended to identify key or critical elements of the disclosure or to limit its scope. Its sole purpose is to present some basic concepts of the disclosure in a simplified form as a prelude to the more detailed description that follows.

[0012] The method for producing carbonated sludge water according to the present disclosure comprises: obtaining sludge water containing carbon dioxide by blowing a gas containing carbon dioxide into sludge water; and obtaining carbonated sludge water by passing the sludge water containing carbon dioxide obtained by obtaining the sludge water containing carbon dioxide through a reactor configured to generate fine bubbles, wherein the reactor comprises a cylindrical member having a flow path formed therein, and a plurality of protrusion members protruding inward from the inner surface of the cylindrical member.

[0013] The carbonated sludge water manufacturing apparatus according to the present disclosure is a carbonated sludge water manufacturing apparatus used in the above-mentioned method for manufacturing carbonated sludge water, and comprises: a flow path for circulating sludge water; an inlet section for injecting a gas containing carbon dioxide into the flow path; and a reactor configured to pass the sludge water containing carbon dioxide and generate fine bubbles, wherein the reactor comprises a cylindrical member having a flow path formed therein, and a plurality of protrusion members protruding inward from the inner surface of the cylindrical member.

[0014] A method for producing mortar or concrete according to the present disclosure includes kneading carbonated sludge water produced by the above-described method for producing carbonated sludge water, cement, and aggregate.

[0015] The above-mentioned and other features of the present disclosure will become apparent from the following description and drawings of the illustrated embodiments of the present disclosure. FIG. 1 is a cross-sectional view of a reactor 1 taken along a flow direction S. FIG. 2 is a schematic diagram showing one aspect of an apparatus M for producing carbonated sludge water according to this embodiment. FIG. 3 is a schematic diagram showing another aspect of an apparatus M for producing carbonated sludge water according to this embodiment. FIG. 4 is a schematic diagram showing the CO ２ The horizontal axis represents supply time, and the ２ 5 is a graph obtained by plotting the CO / CaO and pH of the sludge water on the vertical axis. ２ The horizontal axis represents supply time, and the ２ 6 is a graph obtained by plotting the CO / CaO and pH of the sludge water on the vertical axis. ２ The horizontal axis represents supply time, and the ２ 7 is a graph obtained by plotting the CO / CaO and pH of the sludge water on the vertical axis. ２ The horizontal axis represents supply time, and the ２ 8 is a graph obtained by plotting the CO / CaO and pH of the sludge water on the vertical axis. ２ The horizontal axis represents supply time, and the ２ 9 is a graph obtained by plotting the CO / CaO and pH of the sludge water on the vertical axis. ２ The horizontal axis represents supply time, and the ２ 1 is a graph obtained by plotting CaO and the pH of sludge water on the vertical axis.

[0016] The following describes the method for producing carbonated sludge water, the apparatus for producing carbonated sludge water, and the method for producing mortar or concrete according to this embodiment.

[0017] (Method for producing carbonated sludge water) The method for producing carbonated sludge water according to this embodiment is a method for producing carbonated sludge water by reacting calcium oxide in sludge water with carbon dioxide, and comprises the following steps: Step (1): obtaining sludge water containing carbon dioxide by blowing a gas containing carbon dioxide into sludge water; and Step (2): passing the sludge water containing carbon dioxide obtained in Step (1) through a reactor configured to generate fine bubbles to obtain carbonated sludge water.

[0018] In this specification, sludge water refers to water containing sludge solids, which is obtained by removing aggregate from the wastewater used to wash vehicles, mixers, and other equipment in ready-mix concrete plants. The sludge solids are mostly composed of hydration products and also contain aggregate particles. The hydration products include calcium-based compounds, such as calcium oxide, calcium hydroxide, calcium silicate hydrate, and calcium aluminate hydrate.

[0019] The cement that is a raw material for ready-mixed concrete is not particularly limited, and examples that can be used include Portland cements such as ordinary Portland cement, high-early-strength Portland cement, extra-high-early-strength Portland cement, low-heat Portland cement, moderate-heat Portland cement, sulfate-resistant Portland cement, and white Portland cement, as specified in JIS R 5210:2019; mixed cements such as blast-furnace cement, fly ash cement, and silica cement; extra-rapid-hardening cement, and alumina cement. Note that one type of cement may be used alone, or two or more types may be used in combination.

[0020] <Step (1)> In step (1), sludge water containing carbon dioxide is obtained by blowing a gas containing carbon dioxide into sludge water.

[0021] Examples of the carbon dioxide-containing gas to be blown into the sludge water include industrial carbon dioxide, air, carbon dioxide generated during the burning of cement clinker, and exhaust gases containing nitrogen oxides.

[0022] The concentration of carbon dioxide contained in the carbon dioxide-containing gas is not particularly limited, and may be, for example, 0.004% by volume or more and 100% by volume or less.

[0023] The flow rate of the carbon dioxide-containing gas is not particularly limited, and may be, for example, 1 L / min or more and 1000 L / min or less.

[0024] The molar concentration of carbon dioxide per 1 L of sludge water is not particularly limited, and may be, for example, 0.001 mol / L or more and 0.2 mol / L or less.

[0025] The molar concentration of carbon dioxide can be calculated from the concentration of carbon dioxide, the flow rate of the gas containing carbon dioxide, the gas injection time, and the gas volume per mole under standard conditions (0°C, 1 atmosphere) using the following formula (1): Molar concentration of carbon dioxide (mol / L) = [{(carbon dioxide concentration (vol %) / 100) × gas flow rate (L / min) × gas injection time (min)} / 22.4] / amount of sludge water (L) ... (1)

[0026] The ratio of the mass of sludge solids in the sludge water to the volume of carbon dioxide injected into the sludge water per minute is preferably 0.0200 kg / L or more, and more preferably 0.0400 kg / L or more, from the viewpoint of preventing excessive injection of carbon dioxide-containing gas into the sludge water.

[0027] From the viewpoint of reducing carbon dioxide emissions into the atmosphere, the concentration of the sludge water is preferably 3% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 40% by mass or less. The concentration of the sludge water can be determined based on JIS A 1806:2011.

[0028] The content of calcium oxide contained in the sludge solid content is not particularly limited, but may be, for example, 10 mass % or more and 90 mass % or less relative to the total amount of the sludge solid content.

[0029] The calcium oxide content can be a value obtained by measurement using an X-ray fluorescence analyzer (for example, ZSX Primus IV manufactured by Rigaku Corporation) based on the method specified in JIS R 5204:2019.

[0030] The molar concentration of calcium oxide contained in 1 L of sludge water is not particularly limited, but may be, for example, 0.06 mol / L or more and 4.50 mol / L or less.

[0031] The molar concentration of calcium oxide can be calculated from the calcium oxide content (mass%), the molecular weight of calcium oxide, and the mass of the sludge solid content using the following formula (2): Molar concentration of calcium oxide (mol / L) = [{amount of sludge water (g) × (sludge concentration (mass%) / 100) × 0.8 × (calcium oxide content (mass%) / 100)} / 56] / amount of sludge water (L) ... (2)

[0032] Step (1) can be carried out in a flow path that circulates sludge water through a reactor. In this case, the flow rate of the sludge water is not particularly limited and may be, for example, 1 L / min or more and 1000 L / min or less.

[0033] <Step (2)> In step (2), the sludge water containing carbon dioxide obtained in step (1) is passed through a reactor configured to generate fine bubbles to obtain carbonated sludge water.

[0034] In this specification, fine bubbles are bubbles with a volume-equivalent diameter of less than 100 μm, as defined in JIS B 8741-1:2019 and ISO 20480-1:2017. Fine bubbles are classified into two types, microbubbles and ultrafine bubbles, depending on the diameter of the bubbles. As defined in JIS B 8741-1:2019 and ISO 20480-1:2017, microbubbles are fine bubbles with a volume-equivalent diameter in the range of 1 μm or more and less than 100 μm, and ultrafine bubbles are fine bubbles with a volume-equivalent diameter of less than 1 μm.

[0035] From the viewpoint of sufficiently reacting carbon dioxide with calcium oxide in the sludge water, the volume-equivalent diameter of the fine bubbles is preferably 0.001 μm or more and 100 μm or less, more preferably 1 μm or more and 100 μm or less. The volume-equivalent diameter of the fine bubbles can be determined by dynamic image analysis using, for example, a flow-type image analysis particle size / shape measurement device (Particle Insight, manufactured by Shimadzu Science East Japan Co., Ltd.).

[0036] The reactor, which is configured to generate fine bubbles, is provided with a cylindrical member having a flow path formed therein and a plurality of protrusion members protruding inward from the inner peripheral surface of the cylindrical member, from the viewpoint of reducing the release of carbon dioxide into the atmosphere.

[0037] Fig. 1 is a diagram showing an example of a reactor 1, and is a cross-sectional view taken along a flow direction S. The flow direction is the direction in which sludge water flows, and is the direction indicated by the arrow S in Fig. 1.

[0038] As shown in Figure 1, the reactor 1 includes a cylindrical member 11 having a flow path formed therein, and a plurality of protruding members 12 provided so as to protrude inward from the inner peripheral surface of the cylindrical member 11. The protruding members 12 are blade members having a shape twisted by 180° in a spiral shape around the axis of the cylindrical member 11, and six of them are arranged consecutively along the flow direction S. Adjacent blade members may be arranged so as to be offset by a predetermined angle around the axis of the cylindrical member 11, and may be configured to be discontinuous overall. Adjacent blade members may also be arranged so as to rotate in opposite directions around the axis of the cylindrical member 11.

[0039] The number of protrusion members 12 is not particularly limited as long as it is capable of generating fine bubbles, and may be, for example, 8 or more or 58 or less.

[0040] From the viewpoint of facilitating the reaction between carbon dioxide and calcium oxide in the sludge water, such a reactor is preferably a static mixer. Examples of the static mixer include a static mixer.

[0041] The reaction temperature in the reaction between carbon dioxide and calcium oxide is preferably 1°C or higher and 50°C or lower, more preferably 1°C or higher and 35°C or lower, from the viewpoint of reducing the release of carbon dioxide into the atmosphere.

[0042] The reaction temperature can be adjusted, for example, by adjusting the temperature of the sludge water, for example, by leaving the sludge water in a thermostatic chamber or in the natural environment, by using a cooler in a water storage tank for storing the sludge water, or by arranging a cooler in the flow path of the sludge water.

[0043] <Step (3)> The method for producing carbonated sludge water according to this embodiment preferably further includes the following step (3), from the viewpoint of easily managing the gas containing carbon dioxide so that it is not blown into the sludge water in excess.

[0044] In step (3), the pH of the carbonated sludge water obtained in step (2) can be measured.

[0045] The pH can be measured using a pH meter (for example, a glass electrode type hydrogen ion concentration indicator manufactured by Toko Scientific Research Institute Co., Ltd.).

[0046] In the method for producing carbonated sludge water according to this embodiment, steps (1) to (3) can be repeated until the pH measured in step (3) is in the range of 6.0 or more and 7.0 or less, preferably 6.3 or more and 6.8 or less, from the viewpoint of easily controlling the amount of carbon dioxide-containing gas that is not blown into the sludge water in excess.

[0047] The method for producing carbonated sludge water according to this embodiment includes step (1) for obtaining sludge water containing carbon dioxide, and step (2) for obtaining carbonated sludge water. The reactor includes a cylindrical member having a flow path formed therein and a plurality of protruding members protruding inward from the inner circumferential surface of the cylindrical member, thereby reducing the release of carbon dioxide into the atmosphere. Furthermore, the method for producing carbonated sludge water according to this embodiment does not require complex equipment such as a sealed atmospheric pressure vessel, and can easily reduce the release of carbon dioxide into the atmosphere. Therefore, the method for producing carbonated sludge water according to this embodiment can easily reduce the release of carbon dioxide into the atmosphere, especially in an open system.

[0048] Furthermore, the method for producing carbonated sludge water according to this embodiment includes step (1) for obtaining sludge water containing carbon dioxide, step (2) for obtaining the carbonated sludge water, and further step (3) for measuring the pH. By repeating steps (1) to (3) until the pH measured in step (3) falls within the range of 6.0 or more and 7.0 or less, it is possible to easily prevent excessive injection of gas containing carbon dioxide into the sludge water, and thus it is possible to easily further reduce the release of carbon dioxide into the atmosphere.

[0049] (Carbonated sludge water manufacturing apparatus) Hereinafter, a carbonated sludge water manufacturing apparatus M according to an embodiment of the present disclosure will be described with reference to the drawings. Note that in the following drawings, the same or corresponding parts are given the same reference numerals, and their description will not be repeated.

[0050] The carbonated sludge water production apparatus M according to this embodiment will be described with reference to Figure 2. Figure 2 is a schematic diagram showing one embodiment of the carbonated sludge water production apparatus M according to this embodiment. As shown in Figure 2, one embodiment of the carbonated sludge water production apparatus M according to this embodiment comprises a flow path 2 for circulating sludge water, an inlet section 3 for injecting a gas containing carbon dioxide into the flow path, and a reactor 1 configured to pass the sludge water containing carbon dioxide and generate fine bubbles. In Figure 2, the flow direction is indicated by an arrow S.

[0051] The flow path 2 is configured to allow a gas containing carbon dioxide to be blown in from an inlet section 3 described later, and is connected to the lower part of a water storage tank 4 that stores sludge water on the upstream side in the flow direction S, and is connected to a reactor 1 described later on the further downstream side in the flow direction S, so that sludge water can be supplied to the reactor 1. A pump (not shown) is provided in the flow path 2 to allow the sludge water to flow. The shortest distance between the inlet section 3 and the reactor 1 in the flow path 2 may be 0.5 cm or more and 5000 cm or less.

[0052] The blowing section 3 is configured to be able to blow a gas containing carbon dioxide into the flow path 2 upstream of the reactor 1 (described later) in the flow direction S. The blowing section 3 has an adjusting section (not shown) configured to be able to adjust the flow rate of the gas. Examples of the adjusting section include a valve and a regulator.

[0053] The reactor 1 is the same as that used in the carbonated sludge water production method according to the present embodiment. The reactor 1 is connected to the upper side of the water storage tank 4 on the downstream side in the flow direction S, and is configured so that the carbonated sludge water obtained by passing through the reactor 1 can be stored in the water storage tank 4. As a result, the carbonated sludge water production apparatus M according to the present embodiment is configured so that sludge water and / or carbonated sludge water can be circulated.

[0054] The water storage tank 4 may be provided with a pH measuring unit (not shown). The pH measuring unit may be provided above the sludge water storage tank 4 or below the sludge water storage tank 4. The pH measuring unit may use a pH meter similar to that used in the method for producing carbonated sludge water according to the present embodiment.

[0055] The carbonated sludge water manufacturing apparatus M according to this embodiment is used in the method for manufacturing carbonated sludge water according to the above embodiment.

[0056] Specifically, the carbonated sludge water manufacturing apparatus M performs the above step (1) by blowing gas containing carbon dioxide from the blowing section 3 into the sludge water flowing through the flow path 2 to obtain sludge water containing carbon dioxide.

[0057] In addition, the carbonated sludge water manufacturing apparatus M performs step (2) by passing the sludge water containing carbon dioxide obtained in step (1) through reactor 1, generating fine bubbles of carbon dioxide, and obtaining carbonated sludge water.

[0058] In the carbonated sludge water manufacturing apparatus M of this embodiment, the water tank 4 is connected to the reactor 1 above the water tank 4 and to the flow path 2 below the water tank 4, so that the pH of the carbonated sludge water obtained in the step (2) is measured in the pH measuring unit to perform the step (3), and the steps (1) to (3) can be repeated until the pH measured in the step (3) falls within the range of 6.0 to 7.0.

[0059] In addition, as another aspect of the carbonated sludge water manufacturing apparatus M of this embodiment, as shown in Figure 3, the flow path 2 may be connected to a water storage tank 4 on the upstream side of the flow direction S, and the reactor 1 may be connected to a carbonated sludge water storage tank 4' capable of storing carbonated sludge water on the downstream side of the flow direction S.

[0060] The carbonated sludge water production apparatus M according to this embodiment may include a swirling flow section (not shown) configured to extend the reaction time between carbon dioxide and sludge water by adding a swirling flow to the carbonated sludge water obtained in step (2) downstream of the reactor 1 in the flow direction S. The carbonated sludge water production apparatus M may also include a pressure vessel (not shown) configured to apply pressure to the carbonated sludge water downstream of the reactor 1 in the flow direction S.

[0061] In addition, when the carbonated sludge water manufacturing apparatus M is equipped with a swirling flow section, the pressure vessel may be arranged downstream of the swirling flow section in the flow direction S, or upstream of the swirling flow section in the flow direction S.

[0062] The carbonated sludge water production apparatus M according to this embodiment may also include a temperature adjustment unit (not shown) to adjust the temperature of the sludge water and / or the carbonated sludge water. The temperature adjustment unit may be provided in at least one of the reactor 1, the flow path 2, and the water storage tank 4.

[0063] The temperature adjustment unit may be, for example, a cooler such as a chiller.

[0064] In the carbonated sludge water production apparatus M according to this embodiment, the reactor 1 includes a cylindrical member 11 having a flow path formed therein and a plurality of protruding members 12 protruding inward from the inner circumferential surface of the cylindrical member 11. By passing carbon dioxide-containing sludge water through the reactor 1, the sludge water comes into contact with the plurality of protruding members 12 provided on the reactor 1, generating fine carbon dioxide bubbles. By generating fine carbon dioxide bubbles while passing carbon dioxide-containing sludge water through the reactor 1, the carbon dioxide can sufficiently react with calcium oxide in the sludge water, thereby reducing the release of carbon dioxide into the atmosphere. Furthermore, by including the reactor 1, the carbonated sludge water production apparatus M according to this embodiment can easily reduce the release of carbon dioxide into the atmosphere without requiring complex equipment such as a sealed atmospheric pressure vessel.

[0065] (Method for Producing Mortar or Concrete) The method for producing mortar or concrete according to this embodiment includes kneading the carbonated sludge water produced by the above-described method for producing carbonated sludge water, cement, and aggregate.

[0066] The method for producing mortar or concrete according to this embodiment includes carbonated sludge water produced by the method for producing carbonated sludge water. Note that the method for producing mortar or concrete according to this embodiment may also include mixing the carbonated sludge water with other water, such as tap water, industrial water, recycled water, groundwater, river water, or rainwater.

[0067] The amount of the carbonated sludge water to be blended is, for example, a unit amount (kg / m ３ : 1 m of cement composition ３ Mass per unit mass) is 0.5 kg / m ３ More than 300kg / m ３ It is possible to set the amount as follows: When the other water is mixed with the carbonated sludge water, the amount of water blended is the total amount of water blended.

[0068] The cement is not particularly limited, and may be any of the above cements.

[0069] The blending amount of the cement is, for example, a unit amount (kg / m ３ : 1 m of cement composition ３ Mass per unit mass) is 200 kg / m ３ More than 500kg / m ３ When two or more cements are contained, the above blending amount is the total blending amount of the cements.

[0070] The aggregate may be fine aggregate and / or coarse aggregate. Fine aggregate refers to aggregate that passes entirely through a 10 mm mesh sieve and 85% or more by mass passes through a 5 mm mesh sieve, and coarse aggregate refers to aggregate that remains on a 5 mm mesh sieve at 85% by mass (JIS A 0203:2019).

[0071] Examples of fine aggregates include natural sands such as river sand, land sand, mountain sand, sea sand, crushed sand, and crushed limestone sand, as specified in JIS A 5308:2019 Appendix A Aggregates for Ready-Mixed Concrete, and blast furnace slag. Silica sand produced by crushing and classifying silica may also be used. One type of fine aggregate may be used alone, or two or more types may be used in combination.

[0072] The amount of the fine aggregate to be mixed is, for example, a unit amount (kg / m ３ : 1 m of cement composition ３ Mass per unit mass) is 600 kg / m ３ More than 1300kg / m ３ When two or more types of fine aggregate are contained, the above blending amount is the total blending amount of the fine aggregate.

[0073] Examples of coarse aggregates include natural aggregates such as river gravel, mountain gravel, and sea gravel, as specified in JIS A 5308:2019 Appendix A Aggregates for Ready-Mixed Concrete, artificial aggregates such as crushed stone such as sandstone, hard limestone, basalt, and andesite, and recycled aggregates. One type of coarse aggregate may be used alone, or two or more types may be used in combination.

[0074] The amount of the coarse aggregate to be mixed is, for example, a unit amount (kg / m ３ : 1 m of cement composition ３ Mass per unit mass) is 600 kg / m ３ More than 1300kg / m ３ When two or more types of coarse aggregate are contained, the above blending amount is the total blending amount of the coarse aggregate.

[0075] In the method for producing mortar or concrete according to this embodiment, mortar or concrete can be obtained by kneading the carbonated sludge water, cement, and aggregate.

[0076] The method for producing mortar or concrete according to this embodiment includes carbonated sludge water produced from the above-mentioned carbonated sludge water, thereby making it possible to produce mortar or concrete while easily reducing the release of carbon dioxide into the atmosphere.

[0077] The carbonated sludge water production method, carbonated sludge water production apparatus, and mortar or concrete production method of this embodiment are as described above, but the present disclosure is not limited to the above embodiments and various modifications are possible within the scope of the present disclosure. Furthermore, the packaging bag according to the present disclosure is not limited by the effects of the above embodiments. In other words, the disclosed embodiments should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description. Furthermore, the scope of the present disclosure is intended to include all modifications within the meaning and scope of the claims.

[0078] The present disclosure includes the following aspects: [1] A method for producing carbonated sludge water by reacting calcium oxide in sludge water with carbon dioxide, comprising: Step (1): blowing a gas containing carbon dioxide into the sludge water to obtain sludge water containing carbon dioxide, and Step (2): passing the sludge water containing carbon dioxide obtained in Step (1) through a reactor configured to generate fine bubbles to obtain carbonated sludge water, wherein the reactor comprises a cylindrical member having a flow path formed therein and a plurality of protruding members protruding inward from the inner circumferential surface of the cylindrical member. [2] The method for producing carbonated sludge water according to [1] further comprises Step (3): measuring the pH of the carbonated sludge water obtained in Step (2), wherein Steps (1) to (3) are repeated until the pH measured in Step (3) is in the range of 6.0 to 7.0. [3] A method for producing carbonated sludge water according to [1] or [2], wherein in step (1), the ratio of the mass of sludge solids in the sludge water to the volume of carbon dioxide blown into the sludge water per minute is 0.0200 kg / L or more. [4] A method for producing carbonated sludge water according to any one of [1] to [3], wherein the reactor is a static mixer. [5] An apparatus for producing carbonated sludge water used in the method for producing carbonated sludge water according to any one of [1] to [4], comprising: a flow path for circulating sludge water; an inlet for blowing a gas containing carbon dioxide into the flow path; and a reactor configured to pass the sludge water containing carbon dioxide and generate fine bubbles, wherein the reactor comprises a cylindrical member having a flow path formed therein and a plurality of protruding members protruding inward from the inner surface of the cylindrical member. [6] A method for producing mortar or concrete, comprising a step of kneading carbonated sludge water produced by the method for producing carbonated sludge water described in any one of [1] to [4], cement, and aggregate.

[0079] Examples of the present disclosure will be described below, but the present disclosure is not limited to the following examples.

[0080] (Materials used) Cement: Ordinary Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd.) Water: Tap water was used.

[0081] (Preparation of Sludge Water) Cement (1.5 kg, 4.0 kg, 7.9 kg, 16.7 kg, or 26.5 kg) was added to 150 L of tap water, mixed, and left to stand for 30 minutes to obtain sludge water so that the concentration of the sludge water reached the predetermined concentration shown in each Example and Comparative Example in Tables 1 and 2 below.

[0082] (Reactor) A static mixer (1-N33-131-F manufactured by Noritake Co., Ltd., protruding member: spirally twisted shape, number of blades: 6) was used as the reactor. The static mixer was the same as that shown in FIG.

[0083] Furthermore, it was confirmed that the reactor was capable of generating microbubbles by the following method. First, carbon dioxide gas with a concentration of 100% by volume was blown into tap water (flow rate: 25 L / min) at 20 L / min, and the resulting carbon dioxide-containing water was passed through the reactor to generate microbubbles. Then, the bubble size and number ratio of the microbubbles were measured by dynamic image analysis using a flow-type image analysis particle size and shape device (Particle Insight manufactured by Shimadzu Science East Japan Co., Ltd.). As a result, the average bubble size was 57.1 μm and the bubble number concentration was 940 bubbles / mL, confirming that microbubbles were generated. Furthermore, it was confirmed that microbubbles were generated even when the carbon dioxide-containing water was passed through the reactor and then further passed through a swirling flow section and a pressure vessel and subjected to a pressure of 0.2 MPa.

[0084] (Test 1) <Examples 1-1 to 1-7, 1-9 to 1-10, Comparative Example 1> Using a carbonated sludge water production apparatus M in another aspect of this embodiment as shown in Figure 3, carbon dioxide gas with a concentration of 100% by volume was blown into 150 L of sludge water according to the conditions listed in Table 1, and the resulting sludge water containing carbon dioxide was passed through a reactor to obtain carbonated sludge water.

[0085] The carbonated sludge solids obtained by dehydrating the resulting carbonated sludge water were subjected to differential thermal analysis (TG-DTA) to determine the amount of carbon dioxide (unit: mass%) that had been immobilized in the carbonated sludge solids through reaction with calcium oxide. The amount of carbon dioxide released was calculated using the following formula (I) and evaluated based on the following criteria. The results are shown in Table 1. ⊚: The amount of carbon dioxide released was less than 1.0 L / min. ◯: The amount of carbon dioxide released was 1.0 L / min or more and 10.0 L / min or less. ×: The amount of carbon dioxide released exceeded 10.0 L / min.

[0086] In the formula (I), A represents the amount of carbon dioxide blown in (L / min), B represents the flow rate of the sludge solids (kg / min), and C represents the amount of carbon dioxide immobilized in the carbonated sludge solids (% by mass). 1.97 in the formula (I) represents the density of carbon dioxide gas (kg / m ３ )

[0087] Example 1-8 The same procedure as in Example 1-1 was carried out, except that the sludge water containing carbon dioxide was passed through a reactor and then passed through a swirl section and a pressure vessel to apply a pressure of 0.2 MPa. The results are shown in Table 1.

[0088] Comparative Example 1 The same procedure as in Example 1-1 was carried out, except that the sludge water containing carbon dioxide was not passed through the reactor. The results are shown in Table 1.

[0089]

[0090] As can be seen from the results in Table 1, the methods for producing carbonated sludge water in each example that satisfied all of the configurations of the present disclosure released less than 10 L / min of carbon dioxide, meaning that most of the supplied carbon dioxide was carbonated. From this, it can be said that the methods for producing carbonated sludge water in each example can easily reduce the release of carbon dioxide into the atmosphere.

[0091] (Test 2) <Examples 2-1 to 2-5> Using a carbonated sludge water production apparatus M according to one aspect of the present embodiment as shown in Figure 2, carbon dioxide gas with a concentration of 100% by volume was blown into 150 L of sludge water, and the resulting sludge water containing carbon dioxide was passed through a reactor, and the resulting carbonated sludge water was discharged into a water tank, and the pH in the water tank was measured using a pH meter (a glass electrode hydrogen ion concentration indicator manufactured by Toko Scientific Research Institute Co., Ltd.). This procedure was repeated until the pH of the carbonated sludge water fell within the range of 6 or more and 7 or less.

[0092] Carbon dioxide measuring instrument (T&D CO ２ Using a concentration / temperature / humidity data logger, the carbon dioxide concentration in the atmosphere was measured at a point approximately 30 cm from the outlet of the reactor when the pH of the carbonated sludge water reached 6 or more and 7 or less, and the results were evaluated based on the following criteria. The results are shown in Table 2. ○: Carbon dioxide concentration is less than 1500 ppm. ×: Carbon dioxide concentration is 1500 ppm or more.

[0093] Example 2-6 The same procedure as in Example 2-1 was carried out, except that the temperature of the sludge water was set to 5° C. The results are shown in Table 2.

[0094] The time during which carbon dioxide was injected into the sludge water was defined as the carbon dioxide supply time (hereinafter, CO ２ (also referred to as supply time) for Examples 2-1 to 2-6. ２ The horizontal axis represents the ratio of the molar mass of carbon dioxide reacted with calcium oxide to the molar mass of calcium oxide in the sludge water (hereinafter, CO ２ A graph was created in which the CO2 / CaO ratio and the pH of the sludge water were plotted on the vertical axis. ２ For the calcium oxide / CaO, the values ​​obtained using the molar mass of carbon dioxide obtained in an actual test were taken as the measured values, and the values ​​obtained using the molar mass of carbon dioxide that had theoretically reacted with calcium oxide were taken as the theoretical values, and the respective values ​​were plotted. The results are shown in Figures 4 to 9.

[0095]

[0096] As can be seen from the results in Table 2, the methods for producing carbonated sludge water in each example that satisfied all of the configurations of the present disclosure had a carbon dioxide concentration of less than 1,500 ppm, and therefore reduced the amount of carbon dioxide released. This shows that the methods for producing carbonated sludge water in each example allow the injected carbon dioxide to sufficiently react with the calcium oxide in the sludge water, thereby easily reducing the release of carbon dioxide into the atmosphere.

[0097] 4 to 9, in the carbonated sludge water production methods of Examples 2-1 to 2-6, the pH gradually decreases when carbon dioxide is injected into the sludge water, and by injecting carbon dioxide into the sludge water until the pH of the carbonated sludge water reaches a range of 6 to 7, the release of large amounts of carbon dioxide can be suppressed. From this, the present inventors discovered that the pH decreases as the amount of calcium oxide that reacts with carbon dioxide decreases, and that when the pH reaches a range of 6.0 to 7.0, the injected carbon dioxide hardly reacts at all. Therefore, in the carbonated sludge water production methods of each Example, by repeating the above steps (1) to (3) until the pH reaches a range of 6.0 to 7.0, it is possible to easily prevent excessive injection of carbon dioxide-containing gas into the sludge water, thereby further easily reducing the release of carbon dioxide into the atmosphere.

[0098] Furthermore, since the carbonated sludge water produced using the carbonated sludge water of each example can reduce the release of carbon dioxide into the atmosphere, it can be said that the carbonated sludge water can be used to produce mortar or concrete while easily reducing the release of carbon dioxide into the atmosphere.

[0099] REFERENCE SIGNS LIST 1 reactor 11 cylindrical member 12 protruding member 2 flow path 3 blowing section 4 water storage tank 4' carbonated sludge water storage tank M carbonated sludge water manufacturing device S flow direction

Claims

1. A method for producing carbonated sludge water, comprising: blowing a gas containing carbon dioxide into sludge water to obtain sludge water containing carbon dioxide; and passing the sludge water containing carbon dioxide obtained by obtaining the sludge water containing carbon dioxide through a reactor configured to generate fine bubbles to obtain carbonated sludge water, wherein the reactor comprises a cylindrical member having a flow path formed therein and a plurality of protrusion members protruding inward from the inner surface of the cylindrical member.

2. The method for producing carbonated sludge water described in claim 1, further comprising measuring the pH of the carbonated sludge water obtained by obtaining the carbonated sludge water, and repeating the steps of obtaining the sludge water containing carbon dioxide, obtaining the carbonated sludge water, and measuring the pH until the pH measured by measuring the pH is in the range of 6.0 or more and 7.0 or less.

3. A method for producing carbonated sludge water as described in claim 1 or 2, wherein, in obtaining the sludge water containing carbon dioxide, the ratio of the mass of sludge solids in the sludge water to the volume of carbon dioxide blown into the sludge water per minute is 0.0200 kg / L or more.

4. A method for producing carbonated sludge water according to claim 1 or 2, wherein the reactor is a static mixer.

5. An apparatus for producing carbonated sludge water, comprising: a flow path for circulating sludge water; an inlet section for injecting gas containing carbon dioxide into the flow path; and a reactor configured to pass the sludge water containing carbon dioxide and generate fine bubbles, wherein the reactor comprises a cylindrical member having a flow path formed therein and a plurality of protrusion members protruding inward from the inner surface of the cylindrical member.

6. A method for producing mortar or concrete, comprising kneading carbonated sludge water produced by the method for producing carbonated sludge water according to claim 1, cement, and aggregate.

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