Method for removing hydrous deposits

Abstract

To effectively remove hydrous deposits by a simple method, with reduced load to the natural environment.SOLUTION: A method for removing hydrous deposits induces foaming at the original location of hydrous deposits and removes the hydrous deposits through the foaming.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for removing water-containing deposits. [Background technology]

[0002] Hydrated sediments that form in culverts and tunnels can stagnate water flow and cause various problems. For example, sludge-like deposits produced by bacteria, especially iron bacterial sludge, not only look unsightly when they form and accumulate in large quantities, but also cause the deposits to be blown around and contaminated by the wind when vehicles pass by. Furthermore, if iron bacterial sludge accumulates in facilities such as collection pipes, drainage ditches, and drainage pipes installed in culverts and tunnels, drainage becomes insufficient, resulting in water retention and flooding, making it impossible for vehicles to pass through, and causing problems such as rusting of metal components such as rails and fixtures.

[0003] Conventionally, as a measure to suppress sludge-like deposits produced by bacteria, compositions using compounds with bactericidal properties to kill the bacteria themselves, and devices for fixing such compositions have been known (Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 48-2775 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-219173 [Patent Document 3] Japanese Patent Application Publication No. 11-246309 [Patent Document 4] Japanese Patent Application Laid-Open No. 2007-021302 Summary of the Invention [Problem to be solved by the invention]

[0005] Periodically removing the water-containing deposits that form in culverts and tunnels requires a great deal of time and effort. While there are methods to mechanically remove the water-containing deposits, this does not eliminate the time-consuming preparation and work involved, as it requires transporting equipment, power sources, and cleaning water to the work site. Furthermore, this method is difficult to implement given the limited work space and time available. While chemicals such as fungicides can be used to kill bacteria and suppress the formation of water-containing deposits, it is desirable to minimize the use of compounds such as fungicides as much as possible due to their impact on the natural environment.

[0006] The present invention provides a method for removing water-containing sediments that can effectively remove water-containing sediments using a simple technique and that places little strain on the natural environment. [Means for solving the problem]

[0007] The present invention relates to a method for removing a water-containing deposit, which comprises generating foam in situ in the water-containing deposit and removing the water-containing deposit by the foaming. [Effects of the Invention]

[0008] According to the present invention, there is provided a method for removing water-containing sediments that can effectively remove water-containing sediments using a simple technique and that places little strain on the natural environment.

[0009] The removal method of the present invention can fluidize and wash away accumulated hydrous sediments in a simple and safe manner. This can prevent water retention caused by stagnation of drainage flow and contamination of vehicles, equipment, the inside of tunnels, etc. due to scattering of sediments. The removal method of the present invention facilitates fluidization of hydrous sediments and facilitates dispersion of sediment particles, thereby preventing redeposition in drainage ditches and pipes and allowing the sediments to be effectively returned to the natural environment. Furthermore, it can reduce the effort required for collecting and treating sediments. In particular, sediments produced by iron bacteria are rich in iron and are therefore preferable as a nutrient source for aquatic organisms. DETAILED DESCRIPTION OF THE INVENTION

[0010] As a result of intensive research to solve the above problems, the present inventors have found that hydrous sediments can be easily removed from the area where they are deposited by softening them in situ, i.e., in the state where they are present on the inner wall of a tunnel or in a culvert, using foamed bubbles, and then leaving them to flow as spring water, leaks, drainage, etc., and / or by simply spraying water on them.

[0011] The hydrous sediments targeted by the present invention may have physical properties and a size that can be removed by foaming. For example, those that require a large mechanical force to move, such as riverbed gravel or geological layers, or those that are inherently highly fluid, are excluded from the hydrous sediments targeted by the present invention. In other words, the hydrous sediments targeted by the present invention are those that can be fluidized and removed by foaming. Examples of hydrous sediments targeted by the present invention include iron bacterial sludge, biofilms, and biomats derived from the metabolism of microorganisms such as bacteria, as well as particles such as sand, clay, and mud, fallen leaves, fragments of animals and plants, and decaying matter, and mixtures thereof are also possible.

[0012] The removal method of the present invention is suitable for removing hydrous sediments containing metabolites of iron bacteria. Hydrous sediments containing metabolites of iron bacteria contain divalent iron ions (Fe ) in order for iron bacteria (also called iron-oxidizing bacteria, iron-oxidizing bacteria, iron bacteria, etc.) to obtain their own energy. 2+ ) to trivalent iron ions (Fe 3+ It is a deposit containing poorly water-soluble iron compounds (hydroxides, oxides, etc.) that are formed from trivalent iron ions after oxidation to iron (III) and is also called slime, gel, biomat, brown agar-like substance, red water, red mud, or sob. In other words, the life activity of iron bacteria results in the formation of hydrous deposits containing the metabolic products of iron bacteria.

[0013] The hydrous deposit may be a hydrous deposit that includes a portion exposed to the atmosphere.

[0014] The aqueous deposit may, for example, contain 50% by weight or more, even 60% by weight or more, even 70% by weight or more, and 99.5% by weight or less, even 97% by weight or less, even 95% by weight or less of water.

[0015] The hydrous sediment may have a solids content of, for example, 0.5% by mass or more, further 3% by mass or more, further 5% by mass or more, and 50% by mass or less, further 40% by mass or less, further 30% by mass or less. Here, the solids content of the hydrous sediment may be components other than water, and may also include liquid components.

[0016] The hydrous sediment may contain iron. The iron content in the solid content of the hydrous sediment may be, for example, 0.1% by mass or more, further 1% by mass or more, further 5% by mass or more, and 77% by mass or less, further 60% by mass or less, or further 50% by mass or less. In the hydrous sediment, iron exists as an iron compound such as a hydroxide or oxide. In the present invention, the iron content in the hydrous sediment refers to the amount of iron present as an element. This iron content can be measured, for example, by atomic absorption spectrometry.

[0017] From the viewpoint of the foaming removal effect, the flow value of the hydrous sediment may be, for example, 21 mm or more and 45 mm or less. Here, the flow value of the hydrous sediment is determined by placing a cylinder with an inner diameter of 20 mm and a height of 20 mm on a horizontal surface, gently filling the space inside the cylinder with the hydrous sediment without any gaps, smoothing the top surface with a smooth metal plate, and then gently lifting the cylinder vertically. If the shape is not a perfect circle, the average of the major and minor axes is used as the diameter. Furthermore, if water separates and seeps out of the hydrous sediment after the flow has stopped, the portion of the sediment remaining as solid matter is measured.

[0018] Examples of hydrous sediments having the above-mentioned flow values ​​include sediments derived from the metabolism of bacteria, etc., hydrous sediments derived from microorganisms such as biofilms and biomats, inorganic matter containing water such as sand, clay, mud, etc., and organic matter such as fallen leaves, animal and plant debris and / or decayed matter, and mixtures thereof are also possible. Hydrous sediments containing water and solids in the above-mentioned ranges are preferred because they are likely to have the above-mentioned flow values.

[0019] From the viewpoint of the removal effect by foaming, the thickness of the hydrous deposit may be, for example, 0.1 cm or more, further 1 cm or more, further 3 cm or more, and 50 cm or less, further 30 cm or less, and further 20 cm or less. Here, the thickness of the hydrous deposit is the thickness at the point determined to be the thickest by visual inspection. The thickness is measured using a vernier caliper, a ruler, or the like.

[0020] In the present invention, foaming is caused in situ in the hydrous sediment. In the present invention, foaming may be caused on the surface of the hydrous sediment or inside the hydrous sediment. That is, in the present invention, foaming may be caused on the surface and / or inside the hydrous sediment. In the present invention, foaming may be caused by the generation of a gas. From the viewpoint of safety, carbon dioxide or oxygen is preferred, and carbon dioxide, which does not support combustion, is more preferred.

[0021] In the present invention, foaming can be carried out using a foaming agent that foams upon contact with water. Examples of the foaming agent include foaming agents containing the following components (a) and (b): Component (a): one or more compounds selected from organic acids and inorganic acids Component (b): one or more compounds selected from carbonates and bicarbonates

[0022] Component (a) may be either an inorganic acid or an organic acid. From the viewpoint of easily matching the dissolution rate of component (b) and effectively causing reaction and foaming, component (a) is preferably an organic acid, and more preferably one or more compounds selected from organic acids having from 1 to 18 carbon atoms. The number of carbon atoms in the organic acid may be, for example, 2 or more, or even 3 or more, and 14 or less, or even 10 or less.

[0023] Examples of the inorganic acid of component (a) include hydrochloric acid, sulfuric acid, sulfurous acid, nitric acid, phosphoric acid, phosphorous acid, diphosphorous acid, and boric acid.

[0024] Examples of the organic acid of component (a) include: (1) sulfamic acid, sulfanilic acid, p-toluenesulfonic acid, p-toluenesulfonic acid hydrate, m-xylenesulfonic acid, m-xylenesulfonic acid hydrate, benzenesulfonic acid, naphthalenesulfonic acid, alkylnaphthalenesulfonic acid (e.g., butylnaphthalenesulfonic acid), alkylbenzenesulfonic acid (e.g., dodecylbenzenesulfonic acid), phenolsulfonic acid, alkanesulfonic acid (e.g., hexanesulfonic acid, heptanesulfonic acid, tetradecanesulfonic acid), α-olefinsulfonic acid, hydroxyapatite ... (2) organic sulfonic acids such as lucansulfonic acid, taurine, N-methyltaurine, and isethionic acid; (3) monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, octanoic acid, oleic acid, stearic acid, benzoic acid, hydroxybenzoic acid, and salicylic acid, partial neutralization products of the monocarboxylic acids, acid anhydrides of the monocarboxylic acids, and mixtures of esters of the monocarboxylic acids; (4) oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, malic acid, tartaric acid, oxaloacetic acid, aconitic acid, isocitric acid, oxalosuccinic acid, and α-ketoglutaric acid; Dicarboxylic acids such as itaconic acid, citraconic acid, citramalic acid, glutaric acid, diethylglutaric acid, adipic acid, pimelic acid, suberic acid, 2-butyloctanedioic acid, azelaic acid, sebacic acid, dodecanedioic acid, nonenylsuccinic acid, dodecenylsuccinic acid, alkenylsuccinic acid, phthalic acid, isophthalic acid, terephthalic acid, sulfophthalic acid, sulfoisophthalic acid, sulfoterephthalic acid, cyclohexanedicarboxylic acid, and cyclohexenedicarboxylic acid, partially neutralized products of the above dicarboxylic acids, acid anhydrides of the above dicarboxylic acids, and partially esterified products of the above dicarboxylic acids, (4 (5) tetravalent or higher polycarboxylic acids such as butanetetracarboxylic acid, pyromellitic acid, poly(meth)acrylic acid, polymaleic acid, polyepoxysuccinic acid, etc., partial neutralization products of the polycarboxylic acids, acid anhydrides of the polycarboxylic acids, and partial esterification products of the polycarboxylic acids; (6) acids other than those in (1) to (5);Examples include compounds having a phenol skeleton and exhibiting acidity in water, such as phenol, resorcinol, and pyrogallol, and polyphosphates such as phytic acid. Component (a) can be used alone or in combination of two or more.

[0025] As component (a), in addition to so-called protonic acids that exhibit acidity by dissociating hydrogen ions, substances that become protonic acids by hydrolysis or thermal decomposition, Lewis acids that exhibit acidity by hydrolysis, etc. can also be used. Examples of substances that become protonic acids through hydrolysis or thermal decomposition include sodium persulfate, potassium persulfate, ammonium persulfate, potassium monopersulfate (oxone), and aluminum chloride, and examples of Lewis acids include boron trifluoride.

[0026] Component (a) is preferably used in an unneutralized state because it can increase the amount of the active acid required for effervescence, but it can also be used as a partially neutralized product neutralized with an appropriate base for the purpose of improving the dissolution rate and powder properties, or as a mixture of a separately prepared partially neutralized product and a completely neutralized product. Examples of partially neutralized products include monosodium citrate, monosodium fumarate, monosodium maleate, sodium hydrogen sulfate, potassium hydrogen sulfate, ammonium hydrogen sulfate, sodium hydrogen sulfite, potassium hydrogen sulfite, and ammonium hydrogen sulfite.

[0027] Since the combined component (b) is preferably a solid, the component (a) is more preferably a solid acid from the viewpoint of ease of handling. Also, from the viewpoint of safety in use, a carboxylic acid, which is a weak acid, is more preferred.

[0028] From the viewpoint of increasing the foaming amount, the foaming agent used in the present invention may contain component (a) in a proportion of, for example, 35% by mass or more, further 40% by mass or more, further 45% by mass or more, and 80% by mass or less, further 75% by mass or less, or further 70% by mass or less, of the total content of components (a) and (b) (however, when component (c) described below is contained, the content of component (c) is also included in this total).

[0029] Component (b) is one or more compounds selected from carbonates and hydrogen carbonates, and hydrogen peroxide adducts of carbonates (percarbonates) can also be used. Examples of component (b) include sodium carbonate, potassium carbonate, ammonium carbonate, calcium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium percarbonate, and potassium percarbonate. These may be used alone or in combination. In view of availability and ease of handling, component (b) is preferably a compound selected from sodium carbonate and sodium bicarbonate.

[0030] From the viewpoint of increasing the foaming amount, the foaming agent used in the present invention may contain component (b) in a proportion of, for example, 25% by mass or more, further 30% by mass or more, further 35% by mass or more, and 60% by mass or less, further 55% by mass or less, or further 50% by mass or less, of the total content of components (a) and (b) (however, when component (c) described below is contained, the content of component (c) is also included in this total).

[0031] The form of the foaming agent used in the present invention is not particularly limited, but is preferably solid. Specific examples include powder, granules, granules, tablets, and the like. In the case of a solid, it may be molded with an appropriate additive (such as an excipient) as needed, or may be wrapped in a soluble film or paper. The foaming agent used in the present invention may be liquid, but preferably does not contain both component (a) and component (b) in a liquid state in order to avoid reaction (performance deterioration) before use. Furthermore, the foaming agent used in the present invention may be added to the deposit as component (a) and component (b) separately.

[0032] The blowing agent used in the present invention is preferably one that foams upon contact with water, for example, moisture in a hydrous sediment. More specifically, the blowing agent used in the present invention is preferably one that generates gas upon contact with water and forms foam through foaming. More preferably, it is one that generates highly safe carbon dioxide or oxygen through a neutralization reaction or an oxidation-reduction reaction. Even more preferably, it is one that generates carbon dioxide that does not support combustion.

[0033] In the blowing agent used in the present invention, the combination of component (a) and component (b) is not particularly limited, but as described above, a combination that generates carbon dioxide upon contact with water is preferred. From the viewpoint of efficiently generating carbon dioxide upon contact with water, the blowing agent used in the present invention is preferably a combination in which component (a) is a compound selected from dicarboxylic acids and tricarboxylic acids, and component (b) is a compound selected from sodium carbonate and sodium hydrogencarbonate.

[0034] An example of a combination of the foaming agent used in the present invention that generates oxygen and carbon dioxide is a combination in which component (a) is one or more compounds selected from persulfates and monopersulfates, and component (b) is a percarbonate. Among these, the combination of potassium monopersulfate (Oxone) and sodium percarbonate is preferred.

[0035] An example of a combination of the blowing agent used in the present invention that generates oxygen is a combination in which component (a) is one or more compounds selected from persulfates and monopersulfates, and component (b) is hydrogen peroxide. Among these, the combination of sodium persulfate and hydrogen peroxide is preferred.

[0036] Components (a) and (b) are preferably used in a molar ratio that theoretically allows complete reaction, so that no unreacted substances remain and the reaction is complete without waste, and the pH after the reaction is near neutral. In the blowing agent used in the present invention, the molar ratio of components (a) to (b), component (a) / component (b), may be, for example, 0.02 or more, further 0.04 or more, further 0.1 or more, further 0.2 or more, and 50 or less, further 25 or less, further 10 or less, or further 5 or less. The molar ratio of components (a) / component (b) is preferably selected taking into consideration the pH of the environment in which the component is used, etc.

[0037] The blowing agent used in the present invention preferably further contains the following component (c). Ingredient (c): Foam enhancer

[0038] Component (c) is present at and / or near the solid-liquid, gas-liquid, or liquid-liquid interface and is added to exhibit functions such as dispersing solids, emulsifying liquids, reducing interfacial tension at the interface, forming an adsorption layer, and stabilizing bubbles. Component (c) is a preferred component from the viewpoint of enhancing the removal effect of components (a) and (b) through foaming. Regarding component (c), a foam-increasing agent is a substance that has the effect of delaying the coalescence of continuously generated bubbles, thereby suppressing the rapid disappearance of bubbles, and at the same time, increasing the amount of foam by forming stable foam.

[0039] Component (c) may be, for example, a foam-boosting agent having a molecular weight of 700,000 or less. Examples of the component (c) include foam boosters selected from polymer compounds having a molecular weight of 5,000 or more and 700,000 or less, and surfactants having a molecular weight of less than 2,000. The polymeric compound having a molecular weight of 5,000 to 700,000 includes a polymeric compound selected from natural polymers having a molecular weight of 5,000 to 700,000, and semi-synthetic polymers having a molecular weight of 5,000 to 700,000 that are chemically modified natural polymers. Examples of the polymeric compound having a molecular weight of 5,000 to 700,000 include polymeric compounds selected from proteins having a molecular weight of 5,000 to 700,000, protein derivatives having a molecular weight of 5,000 to 700,000, polysaccharides having a molecular weight of 5,000 to 700,000, and polysaccharide derivatives having a molecular weight of 5,000 to 700,000.

[0040] The polymer compound of component (c) may be either a synthetic polymer or a natural polymer, as long as it has the above-mentioned molecular weight, and may further be a semi-synthetic polymer obtained by chemically modifying a natural polymer.

[0041] Among the polymer compounds of component (c), natural polymers and semi-synthetic polymers obtained by chemically modifying natural polymers include proteins, polysaccharides, and derivatives thereof.

[0042] Examples of polysaccharides of component (c) include agar, curdlan, biopoly, gum arabic, alginic acid, cellulose, starch, saccharin, guar gum, galactomannan, xanthan gum, and carrageenan. Examples of the polysaccharide derivative of component (c) include carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, and propylene glycol alginate. From the viewpoint of the effect of removing deposits by foaming, the polysaccharide and its derivative are preferably a polysaccharide and its derivative having a β bond and a molecular weight of 700,000 or less.

[0043] Examples of the protein component (c) include casein, gelatin, peptone, egg white protein, collagen, pea protein, and soy protein. Examples of the protein derivative of component (c) include sodium caseinate, protein hydrolysates, and enzyme-decomposed protein products.

[0044] Examples of the synthetic polymer of component (c) include polyethylene glycol, polypropylene glycol, polyvinyl alcohol, partially saponified polyvinyl acetate, polystyrene sulfonate, poly(meth)acrylic acid-g-polyalkylene glycol, poly(meth)acrylic acid-g-alkoxypolyalkylene glycol, styrene-maleic acid copolymer salt, isobutylene-maleic acid copolymer salt, acrylic acid-maleic acid copolymer salt, and poly(meth)acrylic acid salt.

[0045] The molecular weight of the polymer compound of component (c) may be 5,000 or more, further 10,000 or more, further 15,000 or more, and may be 700,000 or less, further 500,000 or less, or further 300,000 or less, from the viewpoint of achieving a large amount of foaming and an excellent effect of removing deposits.

[0046] Examples of the surfactant of component (c) include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. The surfactant of component (c) is preferably one or more surfactants selected from anionic surfactants and nonionic surfactants. The surfactant of component (c) is preferably a surfactant with a molecular weight of less than 2000.

[0047] Examples of anionic surfactants include alkyl sulfates, alkyl ether sulfates, alkanesulfonates, hydroxyalkanesulfonates, fatty acid salts, and alkyl ether carboxylates. The anionic surfactant may be an anionic surfactant having a molecular weight of less than 2000. Examples of salts of anionic surfactants include alkali metal salts. The anionic surfactant may have a hydrocarbon group having 8 to 18 carbon atoms, such as an alkyl group or an alkenyl group.

[0048] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylamines, polyoxyethylene fatty acid esters, polyoxyethylene hydrogenated castor oil, polyoxyethylene castor oil, glycerin fatty acid esters, polyoxyethylene sorbitol fatty acid esters, sorbitan fatty acid esters, and alkyl monoglycerin ethers. The nonionic surfactant may be a nonionic surfactant having a molecular weight of less than 2000. The nonionic surfactant may have a hydrocarbon group having 8 to 18 carbon atoms, such as an alkyl group or an alkenyl group.

[0049] Examples of cationic surfactants include alkylamine salts, alkyltrimethylammonium salts, and dialkyldimethylammonium salts. The cationic surfactant may have a molecular weight of less than 2000. The cationic surfactant may have a hydrocarbon group having 8 to 18 carbon atoms, such as an alkyl group or an alkenyl group.

[0050] Examples of amphoteric surfactants include alkylbetaine and alkylamine oxide. The amphoteric surfactant may be an amphoteric surfactant having a molecular weight of less than 2000. The amphoteric surfactant may have a hydrocarbon group having 8 to 18 carbon atoms, such as an alkyl group or an alkenyl group.

[0051] From the viewpoint of the effect of removing deposits by foaming, component (c) is preferably one or more foam-boosting agents selected from proteins and derivatives thereof, polysaccharides and derivatives thereof having a β-bond with a molecular weight of 700,000 or less, anionic surfactants, and nonionic surfactants, and more preferably one or more foam-boosting agents selected from proteins and derivatives thereof, and polysaccharides and derivatives thereof having a β-bond with a molecular weight of 700,000 or less.

[0052] From the viewpoint of biological and environmental safety, component (c) is preferably a foam enhancer selected from casein, sodium caseinate, propylene glycol alginate, hydroxyethyl cellulose, and the like, which are also designated as food additives, and each of these preferably has a molecular weight of 700,000 or less.

[0053] The molecular weight of the polymer compound in component (c) is a weight average molecular weight, and for commercially available products, it may be the molecular weight based on the information accompanying the product (e.g., catalog values, etc.). When measuring, it can be measured by a known method, for example, GPC (gel permeation chromatography) method. When measuring, for example, the following conditions can be adopted depending on the object. Furthermore, the molecular weight of the surfactant of component (c) can usually be calculated from the structure. <Polysaccharides and their derivatives> Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated) Column: GMPWXL + GMPWXL (anion) Eluent: 0.2M phosphate buffer / CH3CN=9 / 1 Flow rate: 0.5mL / min. Column temperature: 40℃ Detector: Shodex RI SE-61 differential refractive index detector Standard: Monodisperse polyethylene glycol with known molecular weight <Proteins and their derivatives> Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated) Column: Agilent Bio SEC-5 Eluent: 150 mM phosphate buffer, pH 7.0 Flow rate: 0.3mL / min. Eluent gradient conditions: Isocratic for 10 to 30 minutes Column temperature: 30°C Detector: Shodex RI SE-61 differential refractive index detector Standard: Monodisperse polyethylene glycol with known molecular weight

[0054] The foaming agent used in the present invention contains component (c) in an amount of preferably 0.1 part by mass or more and preferably 200 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 50 parts by mass or less, and still more preferably 25 parts by mass or less, per 100 parts by mass of the total of components (a) and (b), from the viewpoint of preventing residual foam from remaining indefinitely after completion of foam removal and allowing it to disappear within an appropriate time.

[0055] The foaming agent used in the present invention may contain surfactants other than anionic surfactants and nonionic surfactants in an amount of 0.5% by mass or less, preferably 0.3% by mass or less, further preferably 0.1% by mass or less, or even 0% by mass. While the surfactants are components that enhance foaming, the foaming agent used in the present invention is typically discharged into rivers and other locations together with the hydrous sediments after application to the hydrous sediments. Therefore, it is desirable to reduce the surfactant content as much as possible in terms of environmental impact. In the present invention, excellent removal effects are achieved even when the surfactant content in the foaming agent is reduced in this manner.

[0056] In the present invention, examples of methods for adding a foaming agent to a wet sediment, when used to remove iron bacterial sludge generated in a tunnel, include sprinkling a powder mixture on the surface of the wet sediment, placing tablets on the surface of the wet sediment, spraying a liquid on the surface of the wet sediment, embedding powder inside the wet sediment, embedding tablets inside the wet sediment, etc. These methods can cause foaming and remove the wet sediment.

[0057] From the viewpoint of effective removal of water-containing deposits, the foaming agent used in the present invention preferably has a maximum foaming volume of 160 mL or more and 1000 mL or less, further 900 mL or less, further 800 mL or less, or further 700 mL or less when 10 g of the foaming agent is contacted with 40 g of water at 20° C., and the maximum foaming volume is reached in 1 second or more, further 2 seconds or more, further 3 seconds or more, further 500 seconds or less, further 460 seconds or less, further 300 seconds or less, or further 200 seconds or less. As described in the Examples below, this maximum foaming volume is the maximum volume of foam generated (the highest point on the graduated cylinder) when 10 g of the foaming agent is placed in a 1000 mL measuring cylinder (inner diameter 63 mm, made of plastic) and 40 g of water adjusted to 20° C. is added all at once.

[0058] In the present invention, the hydrous sediment can be removed at a removal rate of 30% or more, further 40% or more, and even 50% or more. Here, the removal rate (%) is calculated by [1-(T1 / T0)] × 100, where T0 is the thickness of the hydrous sediment before the hydrous sediment removal process and T1 is the thickness of the hydrous sediment after the hydrous sediment removal process. Furthermore, even if the hydrous sediment removal rate in a single process is, for example, less than 30%, the hydrous sediment removal rate can be further increased by repeating the foaming removal process.

[0059] In the present invention, when removing the water-containing deposit by foaming, an external force other than foaming may be applied to the water-containing deposit, such as a water jet, brush cleaning, or scraping. After removing the water-containing deposits by foaming, the product may be left as it is, or may be washed with water as necessary. [Example]

[0060] <Experimental Example> The powdered foaming agent shown in Table 1 was prepared using the components (A) to (C) shown in Table 1 as shown in Table 1. 10 g of the powdered foaming agent was placed in a 1000 mL measuring cylinder (inner diameter 63 mm, plastic), and 40 g of water adjusted to 20°C was added all at once from above. The volume scale at the top of the foam that was generated and rose was observed, and the maximum foam volume and the time until the maximum foam volume was reached (referred to as the arrival time in the table) were recorded. The results are shown in Table 1.

[0061] [Table 1]

[0062] Sodium caseinate: Tokyo Chemical Industry Co., Ltd., reagent Carboxymethyl cellulose: Daicel Miraize Co., Ltd., CMC Daicel 1190, weight average molecular weight 820,000 Hydroxyethyl cellulose: Daicel Miraize Co., Ltd., HEC Daicel SP400, weight average molecular weight 250,000

[0063] Example 1 (1) Iron bacteria sludge The following tests were carried out on the iron bacteria sludge used in this example. In this example, iron bacteria sludge that had grown in a drainage outlet with an inner diameter of 5 cm installed in a retaining wall (Hannan City, Osaka Prefecture) was randomly selected and used.

[0064] (1-1) Flow value measurement test of iron bacteria sludge A vinyl chloride cylinder with an inner diameter of 20 mm and a height of 20 mm was placed on a horizontal surface, and the space inside the cylinder was gently filled with iron bacteria sludge without leaving any gaps. After smoothing the top surface with a smooth metal plate, the cylinder was gently pulled up vertically and the diameter of the remaining sediment on the horizontal surface was measured. If the diameter was not a perfect circle, the average of the major and minor diameters was used as the diameter. The results are shown in Table 2.

[0065] (1-2) Iron Bacteria Sludge Solids Content Measurement Test Approximately 3 g of the iron bacteria sludge was homogenized by stirring and weighed into a 100 mL beaker and dried at 105°C for 2 hours. The solid content of the iron bacteria sludge was calculated from the difference in mass before and after drying. The results are shown in Table 2.

[0066] (1-3) Iron content measurement test in the solids of iron bacteria sludge The solids obtained in (1-2) above were analyzed by atomic absorption spectrometry to determine the iron content in the solids of the iron bacterial sludge. The results are shown in Table 2.

[0067] [Table 2]

[0068] (2) Example 1-1 20g of foaming agent from Experimental Example 2 in Table 1 was moistened with 2g of polyethylene glycol 400, rolled into balls, and buried in a 31mm thick iron bacteria sludge that had formed in a 5cm diameter drainage outlet (Hannan City, Osaka Prefecture) installed in a retaining wall. Foaming began immediately, and the foam and iron bacteria sludge mixed together and began to flow, gradually being discharged from the drainage outlet. When the inside of the drainage outlet was checked after foaming had stopped, it was confirmed that the iron bacteria sludge had been reduced to a thickness of 3mm (removal rate of 90%).

[0069] (3) Example 1-2 20g of foaming agent from Experimental Example 1 in Table 1 was moistened with 2g of polyethylene glycol 400, rolled into balls, and buried in a 29mm thick iron bacteria sludge that had formed in a 5cm diameter drainage outlet (Hannan City, Osaka Prefecture) installed in a retaining wall. Foaming began immediately, and the foam and iron bacteria sludge mixed together and began to flow, gradually being discharged from the drainage outlet. When the inside of the drainage outlet was checked after foaming had stopped, it was confirmed that the iron bacteria sludge had been reduced to a thickness of 5mm (removal rate of 83%).

[0070] (4) Examples 1-3 20g of foaming agent from Experimental Example 3 in Table 1 was moistened with 2g of polyethylene glycol 400, rolled into balls, and buried in a 32mm thick iron bacteria sludge that had formed in a 5cm diameter drainage outlet (Hannan City, Osaka Prefecture) installed in a retaining wall. Foaming began immediately, and the foam and iron bacteria sludge mixed together and began to flow, gradually being discharged from the drainage outlet. When the inside of the drainage outlet was checked after foaming had stopped, it was confirmed that the iron bacteria sludge had been reduced to a thickness of 20mm (removal rate of 37%).

[0071] From the results of the Examples, it is possible to predict the iron bacteria sludge removal effect of the foaming agents in Table 1 that were not used in the Examples by comparing the maximum foam volume and maximum arrival time with those of the foaming agents used in the Examples.

Claims

1. A method for removing a water-containing deposit, comprising generating foaming in situ of the water-containing deposit and removing the water-containing deposit by the foaming.

2. The method for removing a water-containing deposit according to claim 1 , wherein the water-containing deposit includes a portion exposed to the atmosphere.

3. The method for removing a water-containing deposit according to claim 1 , wherein the water-containing deposit contains water in an amount of 50% by mass or more and 99.5% by mass or less.

4. The method for removing a water-containing deposit according to claim 1 , wherein the water-containing deposit has a solid content of 0.5 mass % or more and 50 mass % or less.

5. The method for removing water-containing deposits according to claim 1 , wherein the water-containing deposits contain iron.

6. The method for removing water-containing deposits according to claim 1 , wherein the water-containing deposits contain metabolites of iron bacteria.

7. The method for removing water-containing deposits according to claim 1 , wherein the flow value of the water-containing deposits is 21 mm or more and 45 mm or less.

8. 2. The method for removing water-containing deposits according to claim 1, wherein the thickness of the water-containing deposits is 0.1 cm or more and 50 cm or less.

9. 2. The method for removing water-containing deposits according to claim 1, wherein carbon dioxide is generated by foaming.

10. The method for removing water-containing deposits according to claim 1 , wherein foaming is carried out on the surface and / or inside of the water-containing deposits.

11. 2. The method for removing water-containing deposits according to claim 1, wherein the foaming is carried out using a foaming agent that foams upon contact with water.

12. The method for removing water-containing deposits according to claim 11, wherein the foaming agent contains the following components (a) and (b): Component (a): One or more compounds selected from organic acids and inorganic acids Component (b): one or more compounds selected from carbonates and hydrogen carbonates.

13. The method for removing water-containing deposits according to any one of claims 1 to 12, wherein the water-containing deposits are removed at a removal rate of 30% or more.