Hydrated deposit removing agent

Abstract

The present invention provides: a hydrated deposit removing agent which is capable of effectively softening a hydrated deposit by a simple method so as to easily remove the hydrated deposit, especially iron bacteria sludge; and a method for removing a hydrated deposit using the removing agent.　The hydrated deposit removing agent contains 50 mass% to 100 mass% inclusive of an organic acid powder, wherein the median diameter (D50) of the organic acid powder is 0.3 mm or more. The hydrated deposit removing agent is used to remove a hydrated deposit, particularly iron bacteria sludge.

Description

Water-containing sediment remover

[0001] The present invention relates to a water-containing sediment removal agent and a method for removing water-containing sediments. Background Art

[0002] Water-containing deposits that form in culverts and tunnels can cause water stagnation and lead to various problems. For example, sludge-like deposits produced by bacteria, especially iron bacteria sludge, when produced and accumulated in large quantities, are not only unsightly but can also cause scattering and contamination due to wind from passing vehicles. Furthermore, if iron bacteria sludge accumulates in equipment such as water collection pipes, drainage ditches, and drainage pipes installed in culverts and tunnels, insufficient drainage can lead to water stagnation and flooding, making it impossible for vehicles to pass, and causing metal components such as rails and fasteners to rust.

[0003] Japanese Patent Publication No. 59-164398 discloses a solution-type cleaning agent for elevated water tanks or underground water tanks, in which two or more organic acids selected from the group consisting of oxalic acid, lactic acid, tartaric acid, citric acid, gluconic acid, ascorbic acid, and malic acid are used as active ingredients and dissolved in water. Japanese Patent Publication No. 2023-163132 discloses a softening agent for water-containing sediments containing hydroxypolycarboxylic acid, and the examples disclose that a powdered softening agent containing various acids was packed into a rice ball mold and compressed. Summary of the Invention

[0004] Citric acid is a versatile material with many uses, such as being dissolved in a solvent (water) and used as a solution-type cleaning agent, as described in Japanese Patent Publication No. 59-164398. When used as a cleaning agent, it is usually used in solution form. Examples of its use in powder form include lemonade mixed with other materials and acidulants, but there have been no prior disclosures of powdered citric acid being used as a cleaning agent, and no prior examples regarding suitable particle size or particle size distribution for such applications are known.

[0005] Generally, when using powders by scattering them, the selection of particle size is important depending on the application. Larger particle sizes result in better fluidity, but inferior dissolution speed and uniformity of mixing with other powders. Conversely, while smaller particle sizes result in better dissolution speed and uniformity of mixing with other powders, it is known that powder fluidity tends to deteriorate.

[0006] Furthermore, when dispersing powder by hand or with tools, it is considered preferable for the particles to be moderately large (i.e., moderately large in mass) because they are less affected by air resistance and can be dispersed forcefully to the desired area. On the other hand, if the particles are too large, although they may have force, their mass is too great, and they may not adhere effectively to the desired area, sometimes falling due to their own weight.

[0007] Furthermore, when the particle size is small (i.e., has a small mass), it is difficult to accurately apply the substance to the desired area due to dust generation during application and the effects of air resistance.

[0008] As a result of diligent research, the inventors found that citric acid powder with a median diameter (D50) of 0.3 mm or more is suitable for application as a cleaning agent and the like.

[0009] The present invention provides a water-containing sediment removal agent that can effectively soften water-containing sediments, particularly iron bacteria sludge, using a simple method, and a method for removing water-containing sediments using the removal agent.

[0010] The present invention relates to a water-containing deposit remover containing an organic acid powder having a specific median diameter, particularly a hydroxypolycarboxylic acid powder.

[0011] Furthermore, this invention relates to a method for removing water-containing sediments, particularly iron bacteria sludge, by applying a water-containing sediment removal agent to the water-containing sediments.

[0012] The present invention provides a water-containing sediment remover containing a hydroxypolycarboxylic acid that can effectively soften water-containing sediments, particularly iron bacteria sludge, to facilitate their removal. Furthermore, the present invention provides a simple method for effectively removing water-containing sediments, particularly iron bacteria sludge. [Description of modes for carrying out the invention]

[0013] The present invention provides a method for removing water-containing sediments (hereinafter referred to as the "removal method") that uses a water-containing sediment removal agent containing organic acid powder (hereinafter referred to as the "removal agent") to break down the coagulation structure of accumulated water-containing sediments, particularly iron bacteria sludge, thereby promoting solid-water separation. This makes the separated solid components easily fluid, and after applying the removal agent, they can be easily washed away, for example, by a washing operation that reduces water flow and energy load. This prevents water stagnation caused by stagnant drainage flow, contamination of vehicles, equipment, tunnel interiors, etc., by scattered sediment, and rusting of metal components such as rails and fasteners. Using the removal method of the present invention makes water-containing sediments more fluid and sediment particles more easily dispersed, thus suppressing redeposition in drainage ditches and pipes and allowing them to be effectively returned to nature. Furthermore, it reduces the effort required for sediment collection and treatment, and the sludge produced by iron bacteria is particularly desirable because it is rich in iron, making it a nutrient source for aquatic organisms.

[0014] The removal agent of the present invention contains organic acid powder as an active ingredient. In the present invention, "powder" refers to an aggregate of particles that can be recognized as isolated particles, and does not have to consist of particles of a single composition as long as it has the following predetermined average particle size, and may be a mixture of multiple types of particles with different compositions.

[0015] From the viewpoint of improving the removal effect, the content of organic acid powder in the removal agent of the present invention is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and from the same viewpoint, 100% by mass or less, preferably 95% by mass or less, and more preferably 80% by mass or less.

[0016] The content may be 100% by mass; in other words, the removal agent of the present invention may consist solely of organic acid powder.

[0017] The median diameter (D50) of the organic acid powder is preferably 0.3 mm or more, more preferably 0.35 mm or more, and more preferably 0.4 mm or more, from the viewpoint of improving the removal effect, and also preferably 2.0 mm or less, more preferably 1.8 mm or less, and even more preferably 1.5 mm or less. The median diameter (D50) of the organic acid powder can be measured using sieving by the method of the example.

[0018] Furthermore, from the viewpoint of improving the removal effect, the organic acid powder preferably contains 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less of powder smaller than 0.3 mm.

[0019] From the viewpoint of improving the removal effect, hydroxypolycarboxylic acids are preferred as the organic acids constituting the organic acid powder. Examples of hydroxypolycarboxylic acids include compounds having one or more hydroxyl groups and two or more carboxyl groups. From the viewpoint of improving the removal effect, the total number of carbon atoms in the hydroxypolycarboxylic acid is preferably 3 or more, more preferably 4 or more, and from the same viewpoint, preferably 8 or less, and more preferably 6 or less. From the viewpoint of improving the removal effect, the number of hydroxyl groups in the hydroxypolycarboxylic acid is preferably 1 or more, and from the same viewpoint, preferably 4 or less, and more preferably 2 or less. From the viewpoint of improving the removal effect, the number of carboxyl groups in the hydroxypolycarboxylic acid is preferably 2 or more, and from the same viewpoint, preferably 4 or less, and more preferably 3 or less.

[0020] Examples of hydroxypolycarboxylic acids include those represented by the following general formula (1). [In the formula, n is an integer from 0 to 3. The dotted line indicates no connection or a single connection when n is 1, and no connection when n is 0, 2, or 3. When the dotted line indicates no connection, R １ , R ２ and R ３ Each of these independently consists of a hydrogen atom, a methyl group, a hydroxyl group, or -R. ４ -COOH[R ４represents an alkylene group having 1 to 4 carbon atoms. ] represents a carboxyalkyl group. When the dotted line is a single bond, R １ and R ２ are absent, and R ３ is a hydrogen atom, a methyl group, a hydroxyl group or -R ４ -COOH [R ４ represents an alkylene group having 1 to 4 carbon atoms. ] represents a carboxyalkyl group. ]

[0021] For the hydroxy polyvalent carboxylic acid of the general formula (1), a compound in which a part of the carboxyl group is in the form of a salt with an alkali metal ion, an alkaline earth metal ion, an ammonium ion, etc. may be used, but from the viewpoint of improving the removal effect, it is preferable to use a compound in which all the carboxyl groups are in the acid form.

[0022] Among the hydroxy polyvalent carboxylic acids of the general formula (1), those containing an asymmetric carbon can be used alone as an optical isomer or as a mixture. A mixture is preferable from the viewpoints of easy availability and economy.

[0023] Specific examples of the hydroxy polyvalent carboxylic acid include citric acid, malic acid, tartaric acid, 2-hydroxycitric acid, 2-methylcitric acid, isocitric acid, 2-hydroxyglutaric acid, citramalic acid, tartronic acid, 2-methyltartronic acid, hydroxymaleic acid, hydroxymaleic acid, hydroxymethanetricarboxylic acid, aldic acid and its isomers. Further, hydrates thereof can be used.

[0024] From the viewpoint of improving the removal effect, one or more selected from citric acid, malic acid, and tartaric acid are preferable as the hydroxy polyvalent carboxylic acid, and citric acid is more preferable from the same viewpoint.

[0025] From the viewpoint of improving the removal effect, one or more selected from citric acid, malic acid, and tartaric acid are preferable as the organic acid constituting the organic acid powder of the present invention, and citric acid is more preferable from the same viewpoint.

[0026] The form of the removal agent of the present invention is not particularly limited, but from the viewpoint of convenience, it is preferably a solid. If the removal agent consists only of organic acid powder, the powder can be used as is. Furthermore, if it contains optional components as described later, it can be used in the form of powder, particles, granules, pellets, rods, or other tablet-like forms.

[0027] When the remover of the present invention is a solid, the median diameter (D50) of the remover is preferably 0.3 mm or more, more preferably 0.35 mm or more, and even more preferably 0.4 mm or more, from the viewpoint of improving the removal effect. Also from the same viewpoint, it is preferably 2.0 mm or less, more preferably 1.8 mm or less, and even more preferably 1.5 mm or less.

[0028] The removal agent of the present invention may contain one or more compounds selected from carbonates and bicarbonates as optional components to improve the removal effect. Alternatively, hydrogen peroxide adducts (percarbonates) to carbonates can also be used. Specifically, sodium carbonate, potassium carbonate, ammonium carbonate, calcium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium percarbonate, potassium percarbonate, etc., can be used. These may be used individually or in combination.

[0029] When using one or more compounds selected from carbonates and bicarbonates, the content of the compound in the removal agent may be preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the removal agent.

[0030] Other optional components that may be contained in the removal agent of the present invention include inorganic salts such as sodium sulfate, magnesium sulfate, and sodium chloride, colorants, preservatives, rust inhibitors, fragrances, disinfectants, rodenticides, and bittering agents to prevent accidental ingestion. The content of these components can be appropriately set depending on the component, but it is preferable to have 5 parts by mass or less per 100 parts by mass of the removal agent.

[0031] The removal agent of the present invention may be granulated, or optionally, as needed, used as a molded powder with appropriate additives (excipients, etc.), or it may be subjected to operations such as pulverization and sieving after molding. As excipients for molding, hydrophilic polymers such as polyethylene glycol, polyvinyl alcohol, and celluloses, or naturally derived polymers such as agar and gelatin can be used. It may also be used wrapped in a water-soluble or water-soluble film or paper.

[0032] When the material is crushed and sieved after molding, the excipient containing the organic acid is preferably a powder with a median diameter (D50) of 0.3 mm or more and 2.0 mm or less, similar to the organic acid powder. Similarly, when the material is wrapped in a water-soluble or hydrolyzable film or paper, it is preferable that the median diameter (D50) is 0.3 mm or more and 2.0 mm or less, similar to the organic acid powder.

[0033] When additives (such as excipients) are used, the amount contained in the remover is preferably 5 parts by mass or less per 100 parts by mass of the remover.

[0034] The removal agent of the present invention may be used as a dispersion containing organic acid powder and optional components. From the viewpoint of safety, water, ethanol, and isopropyl alcohol are preferred as the dispersion medium for the dispersion. A dispersion containing organic acid powder can be obtained by saturating the organic acid and optional components in these dispersion mediums and then adding the organic acid and optional components to the resulting saturated solution.

[0035] The removal agent of the present invention may take the form of organic acid powder, powder molded by adding an excipient to an organic acid, or the above-mentioned dispersion liquid, but from the viewpoint of improving the removal effect, it is preferable to use it as a powder.

[0036] When the removal agent of the present invention is used in powder form, the median diameter (D50) of the removal agent is preferably 0.3 mm or more, more preferably 0.35 mm or more, and even more preferably 0.4 mm or more, from the viewpoint of improving the removal effect. Also from the same viewpoint, it is preferably 2.0 mm or less, more preferably 1.8 mm or less, and even more preferably 1.5 mm or less.

[0037] Next, a method for removing water-containing sediment using the remover of the present invention will be described. The water-containing sediment targeted by the removal method of the present invention may have physical properties and scales that can exhibit the removal effects of the remover of the present invention, such as the ability to break the aggregated structure and the ability to separate solid-water. For example, those represented by gravel on a riverbed or a formation that require a large mechanical force to move or those that originally have high fluidity are excluded from the water-containing sediment targeted by the present invention. That is, the water-containing sediment targeted by the present invention is a sediment in which solid-water can be separated by the remover according to the present invention and further fluidized and removed. Examples of the water-containing sediment targeted by the removal method of the present invention include sludge, and preferably sludge containing organic substances. Examples of sludge containing organic substances in sludge include iron bacteria sludge derived from the metabolism of microorganisms such as bacteria, biofilms, biomatts, etc., and sludge containing fallen leaves, fragments of animals and plants, and decomposed substances, and mixtures thereof may also be used. In addition, sludge containing particles such as sand, clay, and mud is also included as sludge. The organic substances in the sludge containing organic substances are preferably sludge containing one or more selected from iron oxide and iron hydroxide, more preferably iron bacteria sludge, from the viewpoint of sludge with low fluidity. The content in the sludge containing one or more selected from iron oxide and iron hydroxide is preferably 5% by mass or more, more preferably 30% by mass or more, and preferably 70% by mass or less in terms of iron in the solid content.

[0038] The removal method of the present invention is a method for removing water-containing sediment by applying a remover containing an organic acid powder at the in-situ location of the water-containing sediment. Further, the remover of the present invention can be used in a method for removing water-containing sediment that is applied at the in-situ location of the water-containing sediment and promotes solid-water separation to fluidize and remove the water-containing sediment. The application of the remover is preferably carried out on the surface and / or inside of the water-containing sediment.

[0039] Examples of the method for adding the remover in the removal method of the present invention include spraying a solid remover on the surface of the water-containing sediment, placing a tablet-shaped remover on the surface of the water-containing sediment, embedding a solid, for example, granular remover inside the water-containing sediment, embedding a tablet-shaped remover inside the water-containing sediment, and the like. In addition, when the remover is a dispersion liquid, general methods such as spraying can be used.

[0040] From the perspective of the removal effect, the water content of the water-containing sediment targeted by the removal method of the present invention is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 94% by mass or more in the water-containing sediment, and is preferably 99.5% by mass or less, more preferably 99% by mass or less, still more preferably 98% by mass or less.

[0041] From the perspective of the removal effect, the content of the solid matter of the water-containing sediment targeted by the removal method of the present invention is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 2% by mass or more in the water-containing sediment, and is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 6% by mass or less. The solid matter of the water-containing sediment refers to the residue when water is evaporated.

[0042] The water-containing sediment targeted by the removal method of the present invention may contain iron. The content of iron in the solid matter in the water-containing sediment may be, for example, preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 5% by mass or more, and is preferably 77% by mass or less, more preferably 60% by mass or less, still more preferably 50% by mass or less. In the water-containing sediment, iron exists, for example, as iron compounds such as hydroxides and oxides. In the present invention, the content of iron in the water-containing sediment indicates the amount of iron present as an element. Also, this iron content can be measured, for example, by atomic absorption spectrometry.

[0043] The removal method of the present invention is suitable for the removal of sludge containing metabolites of iron bacteria (hereinafter abbreviated as iron bacteria sludge). The sludge containing metabolites of iron bacteria is a sediment containing poorly water-soluble iron compounds (hydroxides, oxides, etc.) generated from trivalent iron ions after iron bacteria (also called iron-oxidizing bacteria, iron-oxidizing bacteria, iron bacteria, etc.) oxidize divalent iron ions (Fe ２＋ ) to trivalent iron ions (Fe ３＋ ), and is also called slime, gel, biofilm, brown agar-like substance, red water, red mud, sob, etc. That is, as a result of the life activities of iron bacteria, sludge containing metabolites of iron bacteria has occurred.

[0044] Examples of methods for adding a removal agent in the iron bacteria sludge removal method of the present invention include sprinkling a solid, for example, granular, removal agent on the surface of the iron bacteria sludge generated in the tunnel; placing a tablet-shaped removal agent on the surface of the iron bacteria sludge; embedding a solid, for example, granular or powdered, removal agent inside the iron bacteria sludge; and embedding a tablet-shaped removal agent inside the iron bacteria sludge.

[0045] The amount of the removal agent of the present invention used is not particularly limited, but can be appropriately adjusted according to the thickness, hardness, moisture content, and desired level of removal of the water-containing sediment. For example, the amount of the removal agent of the present invention used per liter of water-containing sediment is preferably 1 g or more, more preferably 5 g or more, even more preferably 10 g or more, and may be preferably 600 g or less, more preferably 500 g or less, even more preferably 400 g or less, even more preferably 300 g or less, even more preferably 200 g or less, and even more preferably 100 g or less.

[0046] The removal agent of the present invention, upon contact with the water-containing sediment, disrupts the cohesive structure of the sediment, promoting solid-liquid separation and softening and fluidizing the remaining solid components. After applying the removal agent of the present invention, the water-containing sediment can be easily washed away from the sediment site by applying water to the sediment, for example, by water present in the surrounding environment, such as leaks, springs, or drainage, or by performing simple operations. Examples

[0047] <Water-containing sediment> Sediment collected from a reservoir in Wakayama City, Wakayama Prefecture, as shown in Table 1 below, was used as a model sludge for water-containing sediment. This sediment has a high moisture content of 95.6% by mass and also contains 8.2% by mass of iron, and its properties are similar to those of iron bacteria sludge.

[0048] <Manufacturing of the Removal Agent> Commercially available citric acid powder was sieved using the following method to obtain powder with a predetermined D50. Sieves with mesh sizes of 0.15 mm, 0.30 mm, 0.50 mm, 0.60 mm, 0.71 mm, 1.18 mm, and 2.36 mm were assembled on the bottom of a container in order from the bottom, and 100 g of commercially available citric acid powder was sieved through them. This operation was repeated to obtain citric acid powders having D50 as shown in Examples 1 to 6 and Comparative Example 1 in Table 1. The value of D50 was defined as the average of the mesh size of the sieve through which all the powder passed and the mesh size of the sieve with a smaller mesh size through which no powder passed. For example, in Example 1, the powder that passed through the 3.35 mm sieve but not the 2.36 mm sieve was recovered. In this case, the value of D50 was calculated as (3.55 mm + 2.46 mm) ÷ 2 = 2.86 mm. The granulated sugar, sodium saccharin dihydrate, and sand (mountain sand from Joyo, Kyoto Prefecture) used in Comparative Examples 2 to 4 were similarly sieved, and the value of D50 was calculated.

[0049] Furthermore, if the powder is distributed across two or more sieves, a graph can be created with the average value obtained from the mesh opening of each sieve on the horizontal axis and the sum of the mass percentage of the powder in that sieve and the mass percentage of the powder that passed through the sieve before (cumulative value) on the vertical axis. An approximation curve can then be drawn connecting the cumulative values ​​in order of particle size, and the particle size at which the value of this approximation curve becomes 50% can be determined as D50.

[0050] <Flowability Test Using Model Sludge> 30g of model sludge was placed on a smooth metal plate that was set up horizontally, such that the center of the model sludge was 30cm from the bottom when the plate was placed vertically. Then, the metal plate was gently placed vertically, creating a state where the model sludge adhered to the wall surface. 20g of the removal agent was manually sprinkled onto the model sludge from a distance of 30cm from the metal plate. The time from sprinkling to the start of flow was defined as the flow onset time, and it was evaluated as excellent if it was less than 5 seconds, good if it was between 5 seconds and 15 seconds, and bad if it was 15 seconds or more. The results are shown in Table 2.

[0051] In Examples 1 to 6, which used citric acid powder with a D50 of 0.40 mm or more, flow started in less than 15 seconds in all cases. In Example 1, with a D50 of 2.86 mm, the flow start time was slightly longer than in Examples 2 to 6, where the D50 was 1.77 mm or less. Comparative Example 1, which used citric acid powder with a D50 of 0.23 mm or less, required 15 seconds or more to start flowing. Similarly, Comparative Examples 2 to 4, which were not organic acids, also required 15 seconds or more to start flowing.

[0052] <Measurement of Sediment Removal Rate Using Model Sludge> 30g of model sludge was placed on a smooth metal plate that was set horizontally, such that the center of the model sludge was 30cm from the bottom when the plate was placed vertically. Then, the metal plate was gently placed vertically, creating a state where the model sludge adhered to the wall surface. 20g of the removal agent was manually sprinkled onto the model sludge from a distance of 30cm from the metal plate. Five minutes after the removal agent was sprinkled, the mass of the model sludge remaining attached to the metal plate was measured, and the removal rate was calculated using the following formula. The results are shown in Table 2. Removal rate = [(30g - Amount of residual sediment (g)) ÷ 30g] × 100 (%)

[0053] In Examples 1 to 6, which used citric acid powder with a D50 of 0.40 mm or more, a removal rate of 68% or more was obtained in all cases. In Example 1, where the D50 was 2.86 mm, the removal rate was slightly lower than in Examples 2 to 6, which used citric acid powder with a D50 of 1.77 mm or less. In Comparative Example 1, which used citric acid with a D50 of 0.23 mm, the removal rate was 63%, which was lower than in Examples 1 to 6. Furthermore, in Comparative Examples 2 to 4, which used organic compounds other than organic acids or sand, no sediment was removed at all.

[0054]

Claims

1. A water-containing sediment remover containing 50% by mass or more and 100% by mass or less of organic acid powder, wherein the median diameter (D50) of the organic acid powder is 0.3 mm or more.

2. The water-containing sediment remover according to claim 1, wherein the form is solid.

3. The water-containing sediment remover according to claim 1 or 2, wherein the median diameter (D50) of the organic acid powder is 0.3 mm or more and 2.0 mm or less.

4. The water-containing sediment remover according to any one of claims 1 to 3, wherein the organic acid powder is a powder containing 50% by mass or less of particles smaller than 0.3 mm.

5. The water-containing sediment remover according to any one of claims 1 to 4, comprising 100% by mass of the organic acid powder.

6. The water-containing deposit remover according to any one of claims 1 to 5, wherein the organic acid constituting the organic acid powder is one or more selected from hydroxypolycarboxylic acids.

7. The water-containing deposit remover according to any one of claims 1 to 6, wherein the organic acid constituting the organic acid powder is a hydroxypolycarboxylic acid having 4 to 6 carbon atoms.

8. The aqueous deposit remover according to any one of claims 1 to 7, wherein the organic acid constituting the organic acid powder is one or more selected from hydroxy polyvalent carboxylic acids represented by the general formula (1). [In the formula, n represents an integer of 0 to 3. The dotted line indicates no bond or a single bond when n is 1, and no bond when n is 0, 2, or 3. When the dotted line indicates no bond, R １ , R ２ and R ３ each independently represents a hydrogen atom, a methyl group, a hydroxyl group, or -R ４ -COOH [R ４ represents an alkylene group having 1 to 4 carbon atoms. ] represents a carboxyalkyl group. When the dotted line represents a single bond, R １ and R ２ are absent, and R ３ represents a hydrogen atom, a methyl group, a hydroxyl group, or -R ４ -COOH [R ４ represents an alkylene group having 1 to 4 carbon atoms. ] represents a carboxyalkyl group. ] 9. The water-containing sediment remover according to any one of claims 1 to 8, wherein the organic acid constituting the organic acid powder is one or more selected from citric acid, malic acid, and tartaric acid.

10. The water-containing sediment remover according to any one of claims 1 to 9, wherein the organic acid constituting the organic acid powder is citric acid.

11. The water-containing sediment remover according to any one of claims 1 to 10, further comprising one or more compounds selected from carbonates and bicarbonates.

12. A method for removing water-containing sediment, comprising spraying a water-containing sediment removal agent according to any one of claims 1 to 11 onto the water-containing sediment, wherein the water content of the water-containing sediment is 80% by mass or more and 99.5% by mass or less.

13. The method for removing water-containing sediment according to claim 12, wherein the water-containing sediment is iron bacteria sludge.

14. A method for removing water-containing deposits according to claim 12 or 13, applicable to water-containing deposits adhering to a wall surface.

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