Foam separation apparatus and foam separation method

Abstract

To provide a foam separation apparatus and a foam separation method that are capable of concentrating a separation target substance and improving the removal rate of a substance to be removed from the separation target substance.SOLUTION: A foam separation apparatus 1 includes: a separation column 2; a treated liquid supply unit 3 that supplies a treated liquid containing a separation target substance into the separation column 2; a foam generation unit 4 that generates foam BL from the treated liquid in the separation column 2; and a hydrophilic solution supply unit 5 that supplies a hydrophilic solution into the separation column 2 for contact with the foam. The separation column 2 includes a column section 21 extending upward, the column section 21 guiding the foam BL upward. The hydrophilic solution supply unit 5 supplies the hydrophilic solution into the column section 21 and allows the hydrophilic solution to flow downward while contacting the foam BL rising in the column section 21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a foam separation apparatus and a foam separation method. [Background technology]

[0002] A foam separation device is known that generates foam (sometimes referred to as foam liquid) in a solution containing a substance to be separated, and separates the substance to be separated by adsorbing it onto the surface of the foam (see, for example, Patent Document 1).

[0003] Foam separators have the advantages of being simple in structure and operation, low in manufacturing and running costs, and low environmental impact. For these reasons, foam separators are used in a variety of fields, including copper flotation, the concentrated removal of toner and oil-based ink dispersed in paper solvents (deinking), the removal of proteins from skin mucus in fish breeding and aquaculture, and for protein separation in the food and pharmaceutical industries.

[0004] In the separation device (foam separation device) described in Patent Document 1, foam is generated in the liquid to be treated, which contains organic compounds containing inorganic salts, and the organic compounds (substances to be separated) are separated from the inorganic salts (substances to be removed) by the foam. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-197650 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in conventional foam separation devices such as those described in Patent Document 1, the amount of the substance to be removed from the substance to be separated is small, and the removal rate of the substance to be removed from the substance to be separated cannot be improved. In addition to foam separation devices, there are separation devices that use ion exchange resins, ion exchange membranes, reverse osmosis membranes (RO membranes), nanofiltration membranes (NF membranes), ultrafiltration membranes (UF membranes), etc., but these devices cannot simultaneously separate and concentrate the substances to be separated and improve the removal rate of the substances to be removed from the substances to be separated.

[0007] An object of the present invention is to provide a foam separation apparatus and a foam separation method that can concentrate a substance to be separated and improve the removal rate of a substance to be removed from the substance to be separated. [Means for solving the problem]

[0008] The foam separation apparatus of the present invention comprises a separation tower, a treated liquid supply section that supplies a treated liquid containing a substance to be separated into the separation tower, a foam generation section that generates foam from the treated liquid in the separation tower, and a hydrophilic solution supply section that supplies a hydrophilic solution for foam contact into the separation tower, wherein the separation tower comprises a tower section that extends upward and guides the foam upward in the tower section, and the hydrophilic solution supply section supplies the hydrophilic solution into the tower section and causes the hydrophilic solution to flow downward while coming into contact with the foam rising in the tower section.

[0009] According to the present invention, a hydrophilic solution is supplied into the column section of a separation column and allowed to flow downward while coming into contact with the foam rising in the column section, so that the hydrophilic solution washes away the substances to be removed along the path of the foam movement in the column section, thereby concentrating the substances to be separated and improving the removal rate of the substances to be removed from the substances to be separated.

[0010] In the foam separation apparatus of the present invention, it is preferable that the separation tower has a hydrophilic solution supply port through which the hydrophilic solution supplied from the hydrophilic solution supply section flows into the tower section, and that the hydrophilic solution supply port is provided at the upper end of the tower section.

[0011] According to the present invention, since the hydrophilic solution supply port is provided at the upper end of the tower section, the distance over which the hydrophilic solution flows while coming into contact with the foam within the tower section can be increased, thereby further improving the removal rate of the substance to be removed from the substance to be separated.

[0012] The foam separation method of the present invention includes the steps of supplying a liquid to be treated containing a substance to be separated into a separation tower, generating foam from the liquid to be treated in the separation tower and guiding the foam in a tower section that extends upward in the separation tower, and supplying a hydrophilic solution into the tower section of the separation tower and allowing the hydrophilic solution to flow downward while coming into contact with the foam rising in the tower section.

[0013] According to the present invention, the same effects as those of the foam separation device described above can be obtained. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of a foam separation device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will be described below with reference to FIG. In the following description, when directions are indicated, the state in which the foam separation device 1 is positioned as shown in Figure 1 is used as the reference, with the top being the direction of the Z-axis arrow and the bottom being the opposite direction, the left being the direction of the X-axis arrow and the right being the opposite direction, and the front being the direction toward you in Figure 1 parallel to the Y-axis and the rear being the opposite direction.

[0016] The foam fractionation device 1 is a device for separating a substance to be separated from a liquid to be treated that contains the substance to be separated, and concentrates the substance to be separated and removes the substance to be removed. In this embodiment, the liquid to be treated is a protein solution containing protein as a surfactant, and inorganic salts are used as the substance to be removed, and proteins are separated as the substance to be separated from the protein solution. If the substance to be separated is not a surfactant, a surfactant can be added to the water to be treated.

[0017] In addition to proteins, surfactants include, for example, phenols, anionic, cationic, and nonionic synthetic surfactants, fatty acids, polyhydric alcohols, etc., which can themselves be separated as separation target substances. On the other hand, surfactants are substances having hydrophilic and lipophilic groups, and examples thereof include, but are not limited to, anionic surfactants such as fatty acid salts, higher alcohol sulfate salts, liquid fatty oil sulfate salts, sulfate salts of fatty amines and fatty amides, fatty alcohol phosphate salts, sulfonic acid salts of dibasic fatty acid esters, fatty acid amide sulfonates, alkylarylsulfonates, and formalin condensed naphthalene sulfonic acid; cationic surfactants such as fatty amines, quaternary ammonium salts, and alkylpyridinium salts; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters; and amphoteric surfactants. In addition to inorganic salts, the substances to be removed include organic salts and fine particles. Examples of inorganic salts include sodium salts, calcium salts, magnesium salts, silicates, iron compounds, chlorides, and nitrates. Examples of organic salts include substances that dissociate easily and substances with short alkyl chains, such as sodium acetate and acetylsalicylic acid. Examples of fine particles include hydrophilic particles that are smaller than the plateau boundaries in the foam layer (the liquid channels that connect the bubbles in the foam), such as silica and cellulose particles. The solvent for the liquid to be treated may be, for example, water, alcohol, or a mixture thereof.

[0018] The foam fractionator 1 includes a separation tower 2, a treatment liquid supply section 3, a foam generating section 4, a hydrophilic solution supply section 5, and a residual liquid recovery section 6.

[0019] The separation tower 2 is a cylindrical member made of a transparent or translucent material such as glass or plastic, and has a hollow interior. The separation tower 2 comprises a tower section 21 extending upward, a foam recovery section 22 extending from the upper end of the tower section 21 to the outside of the tower section 21 and recovering foam BL, a hydrophilic solution supply port 23 provided at the upper end of the tower section 21 and through which the hydrophilic solution for foam contact supplied from the hydrophilic solution supply section 5 flows into the tower section 21, a gas supply port 24 and a residual liquid recovery port 25 respectively provided at the lower end of the tower section 21, and a treated liquid supply port 26 provided on the side of the tower section 21.

[0020] The treated liquid supply section 3 includes a treated liquid storage section 31 such as a tank for storing the treated liquid, a pump 33 connected to the treated liquid storage section 31 via piping 32, and piping 34 connecting the pump 33 to the treated liquid supply port 26.

[0021] The foam generating section 4 includes a gas storage section 41 such as a tank or gas cylinder that stores gases such as nitrogen gas or argon gas, a pump 43 connected to the gas storage section 41 via piping 42, a piping 44 connected to the pump 43 and inserted into the gas supply port 24, and a disperser 45 provided at the end of the piping 44 and arranged inside the separation tower 2. The disperser 45 is composed of a porous filter made of glass, metal, ceramic, plastic, resin, or the like, such as a glass filter, so-called air stone, or wood stone.

[0022] The hydrophilic solution supply unit 5 is configured to supply the hydrophilic solution into the tower unit 21 and cause the hydrophilic solution to flow downward while coming into contact with the foam BL rising in the tower unit 21. In the present embodiment, the hydrophilic solution supply unit 5 supplies deionized water as the hydrophilic solution. The hydrophilic solution supply section 5 includes a hydrophilic solution storage section 51 such as a tank for storing a hydrophilic solution, a pump 53 connected to the hydrophilic solution storage section 51 via piping 52, and piping 54 connecting the pump 53 to the hydrophilic solution supply port 23.

[0023] The residual liquid recovery section 6 includes a pipe 61 connected to the residual liquid recovery port 25 and a water level adjuster 62 connected to the pipe 61, and recovers the residual liquid remaining in the separation column 2.

[0024] A method for separating the target substance using the foam fractionator 1 described above will now be described. First, the liquid to be treated is supplied from the liquid storage section 31 into the separation tower 2 by the pump 33. Next, gas is supplied from the gas storage section 41 into the separation tower 2 by the pump 43, and the gas is dispersed by the disperser 45 and blown into the liquid to be treated in the separation tower 2. The blown gas then turns into bubbles AB in the liquid to be treated. If the substance to be separated is a surfactant, the substance to be separated is adsorbed onto the surface of the bubbles AB, which is the gas-liquid interface. If the substance to be separated is not a surfactant, the substance to be separated is adsorbed onto the surfactant adsorbed onto the surface of the bubbles AB and moves upward in the solution. Note that, since proteins, which are the substance to be separated in this embodiment, are also surfactants, they adsorb onto the surface of the bubbles AB and rise in the liquid to be treated. The bubbles AB then become foams BL, separate from the liquid surface FL of the liquid to be treated, and rise upward in the tower section 21, still adsorbing the substance to be separated.

[0025] When the hydrophilic solution is supplied from the hydrophilic solution storage section 51 into the separation column 2 by the pump 53, the hydrophilic solution flows downward while coming into contact with the foam BL rising in the column section 21. At this time, the proteins contained in the foam BL are irreversibly adsorbed to the interface between the foam BL and the air and do not desorb from the foam BL, whereas the inorganic salts contained in the foam BL and in the liquid between the foam BL are washed away by the supplied hydrophilic solution and fall down the column section 21 together with the hydrophilic solution due to their own weight. As a result, the proteins, which are the substances to be separated, are concentrated and the inorganic salts are removed, and they are recovered together with the foam BL from the foam recovery section 22. The residual liquid containing salts in the separation column 2 is recovered through the water level regulator 62.

[0026] As an example of foam separation using the foam fractionator 1, foam separation was performed on a liquid to be treated, in which 0.05 wt% lactoferrin (a protein) and 0.5 M sodium chloride (an inorganic salt) were dissolved in water, with lactoferrin as the target substance, both when a hydrophilic solution was supplied to the separation tower 2 and when no hydrophilic solution was supplied. As a result, when water was supplied as the hydrophilic solution, the lactoferrin concentration rate was the same as when no hydrophilic solution was supplied, but the sodium chloride concentration rate was significantly lower. In other words, while the protein was concentrated, the inorganic salt was removed without being concentrated, resulting in an improved inorganic salt removal rate. The concentration rates were calculated using the following formula (1), with lactoferrin and inorganic salt as the target substances. Concentration rate = concentration of target substance in foam liquid ÷ concentration of target substance in supplied treated liquid (1)

[0027] According to the above-described embodiment, a hydrophilic solution is supplied into the column section 21 of the separation column 2, and the hydrophilic solution is caused to flow downward while coming into contact with the foam BL rising in the column section 21, so that the hydrophilic solution washes away inorganic salts along the movement path of the foam BL in the column section 21. This makes it possible to concentrate the substance to be separated and improve the removal rate of inorganic salts from the substance to be separated.

[0028] In addition, since the hydrophilic solution supply port 23 is provided at the upper end of the tower section 21, the distance over which the hydrophilic solution flows within the tower section 21 while coming into contact with the foam BL can be made longer, thereby further improving the removal rate of inorganic salts from the substance to be separated.

[0029] As described above, the best configurations, methods, and the like for implementing the present invention have been disclosed in the above description, but the present invention is not limited thereto. That is, although the present invention has been particularly illustrated and described mainly with reference to specific embodiments, those skilled in the art can make various modifications to the above-described embodiments in terms of shape, material, quantity, and other detailed configurations without departing from the scope of the technical idea and purpose of the present invention. Furthermore, the above-disclosed descriptions limiting the shape, material, and the like are provided as examples to facilitate understanding of the present invention and are not intended to limit the present invention. Therefore, descriptions using names of components that are free from some or all of the limitations on shape, material, and the like are included in the present invention.

[0030] For example, the separation tower 2 may be formed of a transparent or translucent material, or may be formed of an opaque material, or may be formed of a metal, ceramic, or the like, and the material, height, diameter, and other dimensions of the separation tower 2 are not particularly limited. The tower section 21 may be provided so as to extend upward so as to guide the foam BL upward, and may be provided so as to extend upward at an angle to the vertical direction, for example. The foam collection section 22 may extend in any direction from the tower section 21; for example, it may extend horizontally from the upper end of the tower section 21, or it may extend above the tower section 21. The hydrophilic solution supply port 23 may be provided above the liquid surface FL of the liquid to be treated in the tower section 21, for example, on the side surface of the tower section 21.

[0031] The liquid to be treated supply section 3 may be connected to the lower end of the tower section 21, for example, and the liquid to be treated may be supplied into the tower section 21 from the lower end.

[0032] The foam generating section 4 may include an agitating blade provided in the separation tower 2, and may generate foam BL from the liquid to be treated by agitating the liquid to be treated with the agitating blade. The foam generating section 4 may be provided with, for example, a self-priming air ejector having a Venturi tube instead of or in combination with the disperser 45, and the air bubbles AB may be generated by the ejector. The gas supplied by the foam generator 4 may or may not be an inert gas. The distributor 45 may be provided detachably on the pipe 44 .

[0033] When supplying the hydrophilic solution into the tower section 21, the hydrophilic solution supply section 5 may pour the hydrophilic solution in to an extent that does not destroy the foam BL, or may drop the hydrophilic solution, or may spray the hydrophilic solution in the form of a mist. The hydrophilic solution supplied by the hydrophilic solution supply unit 5 may be any hydrophilic solution (containing a soluble component), and may be, for example, a solution containing water. [Explanation of symbols]

[0034] 1... foam separation device, 2... separation tower, 3... treated liquid supply section, 4... foam generation section, 5... hydrophilic solution supply section, 6... residual liquid recovery section, 21... tower section, 23... hydrophilic solution supply port, BL... foam.

Claims

1. A separation tower; a liquid to be treated supply unit that supplies a liquid to be treated containing a substance to be separated into the separation tower; a foam generating section that generates foam from the liquid to be treated in the separation tower; a hydrophilic solution supply unit for supplying a hydrophilic solution for foam contact into the separation tower, The separation tower includes a tower section extending upward, and the foam is guided upward in the tower section. The hydrophilic solution supply section supplies the hydrophilic solution into the tower section and causes the hydrophilic solution to flow downward while contacting the foam rising in the tower section.

2. The separation tower is provided with a hydrophilic solution supply port through which the hydrophilic solution supplied from the hydrophilic solution supply section flows into the tower section, and the hydrophilic solution supply port is provided at the upper end of the tower section. The foam separation apparatus according to claim 1,

3. A step of supplying a liquid to be treated containing a substance to be separated into a separation tower; generating foam from the liquid to be treated in the separation tower and guiding the foam through a tower section extending upward in the separation tower; A foam separation method characterized by carrying out a step of supplying a hydrophilic solution into the tower section of the separation tower and flowing the hydrophilic solution downward while contacting the foam rising in the tower section.

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