JP2014039912A - Treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method capable of effectively recovering a fluorine-containing surfactant from treatment target water without flowing out of a treatment agent from a treatment layer.SOLUTION: A treatment method is for removing a fluorine-containing surfactant from treatment target water including the fluorine-containing surfactant. The treatment method includes a step of causing the treatment target water to have contact with a treatment agent. The treatment agent is particles carrying powdered active carbon, and composing a treatment layer held between a pair of support layers. The support layer is composed of support agent particles. An effective diameter of the support agent particles is within a range of -0.5 mm through +0.5 mm with regard to an effective diameter of the treatment agent.

Description

The present invention relates to a treatment method for removing a fluorine-containing surfactant from water to be treated containing the fluorine-containing surfactant.

Perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS) and the like are used as surfactants in the production process of fluoropolymers.
However, due to recent research results and the like, there are concerns about the environmental load of PFOA.

Various methods using activated carbon have been studied as a method for recovering a fluorine-containing surfactant such as PFOA from waste water or the like.
Patent Document 1 discloses a method for recovering PFOA using granular activated carbon. Patent Document 2 discloses granulated activated carbon which is composed of powdered charcoal, solid powder, and a binder and is activated by heating.

Patent Document 3 discloses a method for removing fluorine-containing surfactants such as PFOA, which is excellent in water permeability and more efficiently, as a treatment agent containing powdered activated carbon and supported particles, and a fluorine-containing agent such as the treatment agent and PFOA. There has been proposed a treatment method including a contact step of bringing a treatment target water containing a surfactant into contact therewith.

US Patent Application Publication No. 2005/0000004 Japanese Patent Laid-Open No. 5-262511 JP 2010-269241 A

However, when a treatment layer using such activated carbon is used to form a treatment layer in the ground and collect the fluorine-containing surfactant for groundwater as shown in FIG. However, there was a problem that the amount of fluorinated surfactant recovered from the treatment layer decreased by flowing out into the groundwater, and the recovery ability of the fluorine-containing surfactant in the treatment layer was lowered.

In view of the above-mentioned present situation, the present invention has an object to provide a treatment method in which the treatment agent does not flow out of the treatment layer and the fluorine-containing surfactant can be efficiently recovered from the water to be treated.

The inventors of the present invention have a configuration in which a treatment layer made of a specific treatment agent containing powdered activated carbon is sandwiched between two support layers, the effective diameter of the treatment agent forming the treatment layer, and the support particles forming the support layer By having a specific relationship with the effective diameter of the treatment, even if the water to be treated comes into contact with the treatment agent, the treatment agent does not flow out of the treatment layer, and maintains the recovery ability of the fluorine-containing surfactant in the treatment layer, The present inventors have found that the water to be treated can be efficiently treated, and have completed the present invention.

That is, the present invention is a treatment method for removing the fluorine-containing surfactant from the water to be treated containing the fluorine-containing surfactant, comprising the step of bringing the treatment object water into contact with the treatment agent, The treatment agent is a particle on which powdered activated carbon is supported, and constitutes a treatment layer sandwiched between a pair of support layers, the support layer is made of support agent particles, and the effective diameter of the support agent particles is The treatment method is characterized in that the effective diameter of the treatment agent is −0.5 mm to +0.5 mm.
The effective diameter of the support particles is preferably −0.3 mm to 0 mm, which is the effective diameter of the treatment agent.
The effective diameter of the support particles is preferably 0.3 to 1.3 mm.

According to the treatment method of the present invention, a fluorine-containing surfactant such as PFOA can be efficiently removed from waste water or groundwater.

FIG. 1 is a schematic view of an example of a conventional groundwater treatment method. FIG. 2 is a schematic cross-sectional view showing an example of a treatment layer sandwiched between a pair of support layers in the treatment method of the present invention. FIG. 3 is a schematic cross-sectional view showing an example of a treatment layer sandwiched between a pair of support layers in the treatment method of the present invention. FIG. 4 is a schematic diagram showing an example of an embodiment of the processing method of the present invention. FIG. 5 is a schematic top view of the treatment tank. FIG. 6 is a schematic diagram showing an example of an embodiment of the processing method of the present invention. FIG. 7 is a schematic diagram showing the processing test apparatus used in the examples.

The present invention is a treatment method for removing a fluorine-containing surfactant from water to be treated containing a fluorine-containing surfactant, the method comprising the step of bringing the treatment object water into contact with the treatment agent, Is a particle on which powdered activated carbon is supported, and constitutes a treatment layer sandwiched between a pair of support layers, the support layer is made of support particles, and the effective diameter of the support particles is The effective diameter of the agent is -0.5 mm to +0.5 mm.
For this reason, the treatment agent does not flow out of the treatment layer, and the fluorine-containing surfactant can be efficiently removed from the water to be treated.

The present invention is a treatment method for removing a fluorine-containing surfactant from water to be treated containing the fluorine-containing surfactant.
The fluorine-containing surfactant is preferably at least one selected from the group consisting of perfluorooctanoic acid (PFOA), perfluorooctanoate, perfluorooctane sulfonate, and perfluorooctane sulfonate.
The perfluorooctanoate and perfluorooctanesulfonate may be ammonium salts or alkali metal salts.

The processing method of this invention has the process which makes the said process target water and a processing agent contact.
When the water to be treated and the treatment agent come into contact, the fluorine-containing surfactant contained in the water to be treated is recovered by the treatment agent, and the treated water in which the content of the fluorine-containing surfactant is extremely reduced can be obtained. .
Examples of the method of bringing the treatment target water into contact with the treatment agent include a continuous contact method in which the treatment target water is circulated through the treatment layer formed by filling the treatment agent in a fixed space.

In the treatment method of the present invention, the treatment layer is sandwiched between a pair of support layers.
As a configuration in which the treatment layer is sandwiched between a pair of support layers, for example, as shown in FIG. 2, a treatment layer 12 is laminated on the support layer 11, and a support layer 13 is further laminated on the treatment layer. The configuration (A) made is mentioned.
In the configuration (A), the water to be treated is supplied from the upper part of the support layer 13, circulates through the support layer 13, and then circulates through the treatment layer 12, so that the water to be treated can come into contact with the treatment agent. The water to be treated that has circulated through the treatment layer 12 then circulates through the lower support layer 11.
The upstream support layer 13 can prevent unnecessary solids from flowing into the treatment layer, and can also ensure water permeability. The support layer 11 can prevent the treatment agent forming the treatment layer from flowing out.

Further, as another configuration in which the treatment layer is sandwiched between a pair of support layers, as shown in FIG. 3, the support layer 11, the treatment layer 12, and the support layer 13 are adjacent to each other in the horizontal direction (lateral direction). The formed structure (B) is mentioned.
In the configuration (B), the water to be treated is supplied from the left side of the support layer 11, that is, the side not in contact with the treatment layer 12, circulates through the support layer 11, and then circulates through the treatment layer 12. The water to be treated and the treatment agent can come into contact with each other. Thereafter, the support layer 13 is distributed.
In the configuration (B), the water to be treated can also be supplied from the right side of the support layer 13, that is, the side not in contact with the treatment layer 12. In this case, the water to be treated flows through the support layer 13, and then flows through the treatment layer 12, whereby the water to be treated and the treatment agent come into contact with each other, and then flows through the support layer 11.
In this way, the configuration (B) can distribute the water to be treated from the left side and the right side. For this reason, it is possible to remove the fluorine-containing surfactant without flowing out the treatment agent even in an irregular water flow such as in the ground.

Thus, it is preferable that the processing method of this invention has a process which distribute | circulates the said process target water to a support layer before the process of making the said process target water contact a processing agent.
Furthermore, it is preferable to have the process of distribute | circulating the said process target water to another support layer after the process of making the said process target water contact a processing agent.

The treatment layer and support layer described above will be described in detail below.
(Processing layer)
The treatment layer is composed of a treatment agent.
The treatment agent is a particle on which powdered activated carbon is supported.
That is, the treatment agent is composed of powdered activated carbon and particles (supported particles) as a carrier, and powdered activated carbon is supported on the supported particles.
Here, the term “supporting” refers to supporting the supported particles so as to carry powdered activated carbon.
By supporting the powdered activated carbon on the particles, it is possible to prevent lumps (aggregates) and water permeability from decreasing. Moreover, it becomes difficult to scatter and is excellent in handling property.

The treatment agent is preferably 1 to 100 parts by mass of powdered activated carbon with respect to 100 parts by mass of the supported particles. By setting the amount within the above range, the powdered activated carbon is efficiently supported on the support particles, and thus, the recoverability of the fluorine-containing surfactant is excellent.

The powdered activated carbon preferably has a specific surface area of 100 to 2500 m ² / g. By being the said range, the treatment efficiency of the water containing a fluorine-containing surfactant can be made more excellent. More preferably, it is 500-1000 m < ² > / g. The specific surface area is the sum of the surface area inside the pores and the surface area outside the particles. The specific surface area can be measured by a generally used method, and if it is marketed as a product, the nominal value may be in the above range.

The powdered activated carbon preferably has 90% or more of the total number of particles having a particle size of 200 mesh (sieve nominal size: 0.075 mm) or less. According to this, the powdered activated carbon is efficiently supported on the supported particles, and the powdered activated carbon is supported on the supported particles, so that it is less likely to become lumps (aggregates), more excellent in water permeability, and the fluorine-containing interface. It can be set as the processing agent excellent in the removability of an activator.

Further, as described above, the number of particles passing through a filter having a sieve nominal size of 75 μm is preferably 90% or more of the total number of particles. In general, it is well known that the performance of activated carbon depends on the specific surface area (the specific surface area is the sum of the surface area inside the pores and the surface area outside the particles). The processing efficiency may depend greatly on the particle size. Therefore, by using powdered activated carbon in which the number of particles passing through a filter having a sieve nominal size of 75 μm is 90% or more of the total number of particles, the fluorine-containing surfactant can be efficiently removed.

Examples of the powdered activated carbon include sawdust, wood chips, charcoal (primary ash), bamboo charcoal, grass charcoal (peat), coconut charcoal, coal (lignite, lignite, bituminous coal, anthracite, etc.), oil carbon, phenol resin, and rayon. , Acrylonitrile, coal pitch, petroleum pitch, and those obtained from raw materials such as phenol resin are mentioned, but the present invention is not limited to these.

Examples of the supported particles include filter sand and filter gravel generally used for water purification, but the present invention is not limited to these.

The supported particles preferably have a particle diameter of 0.3 to 3.0 mm from the viewpoint of excellent water permeability and fluorine-containing surfactant removability. When the particle diameter is in the above range, the powdered activated carbon is efficiently supported, so that the treatment agent can be made more excellent in water permeability and removability of the fluorine-containing surfactant. More preferably, the supported particles do not substantially contain particles having a particle diameter exceeding 2.8 mm.

The particle size of the supported particles is obtained by conducting a screening test manually using a standard mesh sieve (JIS Z8801, nominal size: 0.3 to 3.0 mm, sieve size: φ200, depth 45 mm). In order not to include particles having a particle diameter exceeding 2.8 mm, a sieve having a nominal size of 2.8 mm is used.

The carrier particles preferably have a uniformity coefficient of 1.5 or less. When the uniformity coefficient is within the above range, the powdered activated carbon is efficiently supported, and it is possible to obtain a treatment agent that is more excellent in water permeability and excellent in removability of the fluorine-containing surfactant.
The uniformity coefficient of the supported particles is measured according to JWWA A103-1: 2004.

The particle diameter of the powdered activated carbon is preferably smaller than the particle diameter of the supported particles. When the particle diameter of the powdered activated carbon is larger than the supported particles, the contact area with the water to be treated decreases, and the recovery rate of the fluorine-containing surfactant may decrease. Further, the gap between the powdered activated carbons is filled with the support particles, and the density becomes high, and the water permeability may be lowered.
At least the supported particles are particles having a particle size of 0.3 to 3.0 mm, and the powdered activated carbon has a particle size of 200 mesh or less (sieve size: 0.075 mm) or less of 90% or more of the total number of particles. If so, it can be said that the particle diameter of the powdered activated carbon is smaller than the particle diameter of the supported particles.

The treatment agent can be produced, for example, by mixing the powdered activated carbon and the supported particles using a tilted barrel type gravity mixer.

The tilting cylinder type gravitational mixer is such that a mixing container for mixing powdered activated carbon and supported particles is attached to the tilting cylinder mechanism, and may be anything generally referred to as a tilting cylinder type gravitational mixer. . The tilting cylinder mechanism is a mechanism for tilting the mixing container.

As a form of the tilting cylinder type gravitational mixer, for example, a frustoconical container is united, a mixing container having one end opened and the other end closed is attached to a tilting mechanism, and the mixing container What attached the blade | wing for mixing to an inner peripheral wall etc. are mentioned. The mixing container is preferably rotatable.

When mixing the powdered activated carbon and the supported particles, the powdered activated carbon and the supported particles are usually charged while operating the tilting cylinder mechanism so that the opening of the drum faces upward and the mixing container is rotated in a certain direction. The charged materials are mixed by repeating the operation of being lifted by the blades and dropped downward.

In the tilting type gravitational mixer, the mixing is promoted by the behavior of the input material, so that it is possible to mix while maintaining the state in which the powdered activated carbon is supported on the supported particles. Therefore, an especially excellent effect is exhibited in the production of the treatment agent.

As a method for producing the treatment agent, for example, the powdered activated carbon and the supported particles may be put into a mixing vessel of a tilted barrel type gravity mixer, and water may be added and mixed as necessary.

The effective diameter of the treatment agent is preferably 0.3 to 1.6 mm, and more preferably 0.3 to 1.0 mm, from the viewpoint of ensuring water permeability.
The effective diameter is a particle diameter corresponding to the size of a sieve through which 10% by mass of the total mass passes through the treatment agent. Specifically, a screening test was performed manually using a standard mesh sieve (JIS Z8801, nominal size: 0.3 to 1.6 mm, sieve size: φ200, depth: 45 mm), and the total mass The particle diameter corresponds to the size of a sieve through which 10% by mass passes.

The treatment agent preferably has a particle size of 0.3 to 3.0 mm. More preferably, the treatment agent does not contain particles having a particle diameter exceeding 2.8 mm.
The particle diameter of the treatment agent is obtained by manually conducting a screening test using a standard mesh sieve (JIS Z8801, nominal size: 0.3 to 3.0 mm, sieve size: φ200, depth 45 mm). In order not to include particles having a particle diameter exceeding 2.8 mm, a sieve having a nominal size of 2.8 mm is used.

The treatment agent is preferably such that 90% by mass or more of the entire treatment agent has a particle diameter of 0.3 to 3.0 mm, more preferably 95% by mass or more, and still more preferable ratio is It is 99 mass% or more. It is particularly preferable that the treatment agent does not contain particles having a particle size of less than 0.3 mm and does not contain particles having a particle size of more than 3.0 mm.

The thickness of the treatment layer is not particularly limited, and is appropriately set so that the treatment target water can be treated sufficiently and without delay depending on the treatment amount of the treatment target water, the content of contaminants in the treatment target water, and the like. do it. For example, 10 cm or more is preferable.

(Support layer)
The support layer is a layer composed of support agent particles.
The effective diameter of the support agent particles is −0.5 mm to +0.5 mm which is the effective diameter of the treatment agent.
In the present invention, the above-mentioned treatment layer is located between two support layers made of particles having a specific effective diameter. By adopting such a configuration, even when the water to be treated is brought into contact with the treatment agent, the treatment agent does not flow out of the treatment layer, and the recovery ability of the fluorine-containing surfactant in the treatment layer can be maintained. .
The effective diameter of the support agent particles is more preferably −0.3 mm to 0 mm, which is the effective diameter of the treatment agent.

Specifically, the effective diameter of the support particles is preferably 0.3 to 1.3 mm, more preferably 0.3 to 1.0 mm, and 0.3 to 0.6 mm. More preferably. When the effective diameter is in the above range, the treatment agent can be prevented from flowing out of the treatment layer. Further, it is possible to reliably capture and remove the pollutant that causes the blockage.
The effective diameter is a particle diameter corresponding to the size of a sieve through which 10% by mass of the total mass passes through the support particles. Specifically, a screening test was performed manually using a standard screen sieve (JIS Z8801, nominal size: 0.3 to 1.3 mm, sieve size: φ200, depth: 45 mm), and the total mass The particle diameter corresponds to the size of a sieve through which 10% by mass passes.

The particle diameter of the support particles is preferably 0.1 to 3.0 mm.
The particle size of the above support particles was manually screened using a standard screen sieve (JIS Z8801, nominal size: 0.1 to 3.0 mm, sieve size: φ200, depth: 45 mm). Can be sought.
As for the particle diameter of the said support agent particle, 0.3-2.0 mm is more preferable. In order not to include particles having a particle diameter exceeding 2 mm, a sieve device having a nominal size of 2 mm is used.

More preferably, the support particles consist essentially of particles having a particle diameter of 0.1 to 3.0 mm.
That is, as the support particles, 90% by mass or more of the entire support particles preferably have a particle diameter of 0.1 to 3.0 mm, and a more preferable ratio is 95% by mass or more. A more preferable ratio is 99% by mass or more. It is particularly preferable that the support particles do not contain particles having a particle size of less than 0.1 mm and do not contain particles having a particle size of more than 3.0 mm. When the particle diameter of the support particles is within the above range, the treatment agent can be prevented from flowing out of the treatment layer. Further, it is possible to reliably capture and remove the pollutant that causes the blockage.
More preferably, the support particles consist only of particles having a particle size of 0.3 to 2.0 mm.

The support particles are preferably inert so as not to react with the water to be treated.

Although it will not specifically limit as said support agent particle | grains if it has an above-mentioned particle diameter and it is an inactive thing which does not react with process target water, For example, sand is mentioned.
Examples of the material of the sand include quartz and feldspar containing silicon dioxide, aluminum oxide, manganese and the like.
The sand is not limited to a natural product, and may be an artificial product made of the same material as the natural product.

Further, the sand preferably further satisfies at least one of the following characteristics, and more preferably satisfies all of the following characteristics.
(1) Does not contain much dust, clayy impurities, flat or fragile sand, etc., contains a lot of quartz and is hard and even, (2) Low content of iron sand and fragile sand (3) Washing turbidity is 30 degrees or less, (4) Specific gravity (density) is 2.57 to 2.67 (g / cm ³ ), (5) Loss on ignition is 0.75 (6) Abrasion rate is 3% or less, (7) Iron and iron-containing compound content is 0.03 (mg / L) or less, (8) Manganese and manganese content The content of the compound is 0.005 (mg / L) or less, (9) the hydrochloric acid solubility is 3.5% or less.

The support particles preferably have a uniformity coefficient of 1.5 or less. When the uniformity coefficient is within the above range, the treatment agent can be prevented from flowing out of the treatment layer. Further, it is possible to reliably capture and remove the pollutant that causes the blockage.
The uniformity coefficient can be measured in accordance with JWWA A103-1: 2004.

The thickness of the support layer is not particularly limited, so that the treatment target water can be sufficiently and smoothly treated according to the treatment amount of the treatment target water, the content of contaminants in the treatment target water, and the like. What is necessary is just to set suitably. For example, 10 cm or more is preferable.

The two support layers sandwiching the treatment layer may be the same or different within the above-described range.
In the treatment layer and the support layer, the boundary between the two adjacent layers may not be clear, and a region where the components constituting the two layers are mixed may exist between the two adjacent layers.

The treatment layer and the support layer can be formed, for example, by filling the treatment agent and the support agent particles in a fixed space using a known method.
As said fixed space, the space comprised by a column, a tank, etc., the excavation groove formed in the ground, etc. are mentioned, for example.
Specifically, for example, the support agent particles are filled into a constant space to form the support layer A, and the treatment agent is filled into a constant space adjacent to the formed support layer A to form a treatment layer. And the method of filling the support agent particle | grains in the fixed space adjacent to the formed process layer, and forming the support layer B is mentioned.
In this way, a configuration in which the treatment layer is sandwiched between the pair of support layers is formed. The treatment method of the present invention preferably includes a step of forming such a support layer.

In the treatment method of the present invention, the fluorine-containing surfactant in the treatment target water is removed by bringing the treatment target water into contact with the treatment agent. In the present invention, as described above, the treatment layer made of a specific treatment agent is installed in a state of being sandwiched between two support layers made of specific support agent particles. For this reason, when the water to be treated flows through the treatment layer, the treatment agent can be prevented from flowing out of the treatment layer. As a result, the ability of the treatment layer to recover (treat) the fluorine-containing surfactant can be maintained over a long period of time.

The water to be treated is not particularly limited as long as it contains the above-mentioned fluorine-containing surfactant, and the fluorine-containing surfactant content may be small or large. It is preferable that the surfactant is contained at 10000 μg / L or less.
If the concentration of the fluorine-containing surfactant compound in the water to be treated exceeds 10,000 μg / L, the fluorine-containing surfactant may not be sufficiently removed. Although the minimum of the density | concentration of the said fluorine-containing surfactant is not specifically limited, For example, it is 100 microgram / L.

Moreover, when the density | concentration of the fluorine-containing surfactant of process target water exceeds 10000 microgram / L, the processing method of this invention contains 10,000 microgram / L or less of a fluorine-containing surfactant by pre-processing the said process target water. A pretreatment step for obtaining water to be treated may be included. The pretreatment may be performed by a conventionally known treatment method using granular powdered activated carbon.

The treatment method of the present invention is preferably to obtain treated water having a fluorine-containing surfactant concentration of 100 μg / L or less. The concentration of the fluorine-containing surfactant in the treated water is more preferably 10 μg / L or less. Moreover, it is more preferable that it is 3 microgram / L or less, and according to this, the standard value which US Environmental Protection Agency recommends can also be satisfy | filled.

In this specification, the concentration of the above-mentioned treatment target water and the fluorine-containing surfactant in the treated water is as follows using a liquid chromatography-tandem mass spectrometer (LC / MS / MS) manufactured by Waters Corporation. It is a value obtained by measuring with.
-HPLC system main body: 2695 separation module-Mobile phase solvent: acetonitrile 45 vol% / 0.15% acetic acid aqueous solution 55 vol%
-HPLC column: Atlantis dC18 3 μm 2.1 × 30 mm
・ Tandem quadrupole mass spectrometer: Quattro micro API
(C7F15− having a molecular ion mass number of 369 is measured as a monitor ion.)

The treatment target water is not particularly limited as long as it is an aqueous solution containing a fluorine-containing surfactant, and may be an aqueous solution used in a production process of a fluoropolymer, or waste water generated in the production process. Also good. Or general tap water, natural environment water, underground water, and underground water may be sufficient.
Although the said process target water may contain solid content, when there is concern about the influence on process efficiency by containing solid content in large quantities, before the process of making a process target water and a processing agent contact, It is also one of preferable modes to include a step of removing solid content such as filtration.

In the treatment method of the present invention, as a method of bringing the water to be treated into contact with the treatment agent, more specifically, for example, a column or the like is filled with the support agent and the treatment agent and sandwiched between the pair of support layers described above. A treatment layer is formed, and the water to be treated is circulated therein, and a permeation wall in which a treatment layer sandwiched between the pair of support layers is formed is installed in a place where groundwater or the like flows. The method of making a permeation | transmission wall permeate | transmitting using the flow of water is mentioned.

An example of a specific embodiment of the processing method of the present invention will be described.
In FIG. 4, the schematic diagram of an example of the embodiment of the processing method of this invention is shown. In addition, about the processing tank 28, it shows with a cross-sectional schematic diagram.
In FIG. 5, the model top view of the processing tank 28 is shown. 4 is a schematic cross-sectional view taken along line XX ′ of the schematic top view of FIG. 5.

The treatment tank 28 includes at least a treatment layer sandwiched between a pair of support layers in the present invention.
Specifically, as shown in FIG. 4, the treatment tank 28 has a gravel layer 24 and a support layer 25 in order from left to right, that is, in order from the upstream side to the downstream side along the direction in which the water to be treated flows. The treatment layer 26 and the support layer 27 are provided.
In FIG. 4, W ₁ , W ₂ , and W ₃ indicate the thickness of the support layer 25, the thickness of the treatment layer 26, and the thickness of the support layer 27, respectively.
The processing target water is supplied from the processing target water source water tank 21 to the gravel layer 24 by the pump 22 via the processing target water storage tank 23, and then the support layer 25, the processing layer 26, and the support layer 27 in this order. Water to be treated flows from the left side to the right side of 4 and is collected in the treated water collection tank 29. Arrow B indicates the flow direction of the water to be treated. Moreover, the broken line S in a figure shows the water level of process target water.
The treatment target water storage tank 23 and the treatment water recovery tank 29 are, for example, at the same height as the water surface of the treatment target water in the treatment target water storage tank 23 so that the flow rate of the treatment target water is constant. It is preferable that the height of the pipe connected to the treated water recovery tank 29 is adjusted.
A filter or the like may be installed at the outlet of the water to be treated in the treatment tank 28 in order to prevent the support particles constituting the support layer 27 from flowing out.

The shape, size, material and the like of the treatment tank are not particularly limited, and may be appropriately determined according to the treatment amount of the treatment target water, the fluorine-containing surfactant content of the treatment target water, and the like. Examples of the shape of the tank include a cylindrical shape and a box shape. Examples of the material of the tank include plastic and metal.

The gravel layer 24 is a layer for removing solids and allowing water to flow uniformly. Although it does not specifically limit as the gravel which comprises the gravel layer 24, It is preferable that a particle size is 2-50 mm. When the particle size is in the above range, the pollutant causing the blockage can be reliably captured and removed, and uniform water permeability can be ensured. The particle size of the gravel is more preferably 4 to 20 mm.
The particle size of gravel can be measured according to Japan Water Works Association Standard JWWA A103-4: 2006.

Moreover, the schematic diagram of an example of the embodiment of the processing method of this invention is shown in FIG.
FIG. 6 is a view showing a method of treating groundwater by forming a treatment body including a treatment layer 33 sandwiched between a pair of support layers 32 and 34 in the ground as a permeation wall 31 in the present invention. In the figure, A indicates the flow direction of groundwater.
For example, the groundwater flows through the support layer 32 and then flows through the treatment layer 33, whereby the fluorine-containing surfactant contained in the groundwater is recovered, and then flows through the support layer 34.
The transmission wall 31 is formed by forming a excavation groove on the ground and filling the excavation groove with support agent particles and a treatment agent to form a support layer 32, a treatment layer 33, and a support layer 34 in a plate shape. Good.
The transmission wall is preferably installed so as to intersect the flow of groundwater.

Thus, according to the treatment method of the present invention, since the treatment agent does not flow out of the treatment layer, the fluorine-containing surfactant in the water to be treated can be suitably removed, and the removal ability can be maintained for a long time.
The treatment method of the present invention is a method of treating waste water or the like using a treatment tank having a treatment layer sandwiched between the pair of support layers, or a transmission wall having a treatment layer sandwiched between the pair of support layers. It can be applied to a method of treating groundwater using

EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited only to these Examples.

Preparation Example 1 Preparation of Treatment Agent Inclined torso type gravity mixer (capacity 110 L), sand for rapid filtration (manufactured by Tochemi, “Japan Water Boundary Standard JWWA A-103-1: 2004 Standard Product, Effective Diameter: 0.6 mm”) , Uniformity coefficient: 1.5 or less, maximum diameter 2.8 mm or less, minimum diameter 0.3 mm or more ") and powdered activated carbon (manufactured by Nippon Enviro Chemicals, white birch DO-2, particle size 200 mesh (sieve nominal size: 0.075 mm) The following number of particles is 90% or more of the total number of particles and the specific surface area is 940 m ² / g) per 100 parts by mass of the total mass, and 70 parts by mass of sand for rapid filtration and 30 parts by mass of powdered activated carbon are charged. Mixing was performed for 3 minutes to obtain a treating agent.
The effective diameter of the obtained treatment agent was 0.6 mm.

(Example)
FIG. 7 shows the processing test apparatus used in the examples.
As shown in FIG. 7, 20 cm × 40 cm × 30 cm (length × width × depth) resin container as a processing tank 48 is filled with gravel, sand, the processing agent obtained in Preparation Example 1, and sand. Then, a gravel layer 44, a support layer 45 made of sand, a treatment layer 46, and a support layer 47 made of sand were formed. Each layer has a thickness of 10 cm and a height h of 20 cm.
A membrane filter 50 having a hole diameter of 0.3 mm was installed at the water outlet of the treatment tank 48 to be treated.
The gravel and sand used in the examples are as follows.
Gravel: manufactured by Tochemi, particle size 4-8 mm, specific gravity 2.5 or more Sand: sand for rapid filtration, manufactured by Tochemi, “Japan Water Works Association Standard JWWA A103-1: 2006 Standard Product, Effective Diameter: 0.5 mm, Uniformity Coefficient : 1.5 or less, maximum diameter 2.0 mm or less, minimum diameter 0.3 mm or more "

Further, as shown in FIG. 7, the treatment target water source water tank 41 and the treatment target water storage tank 43 are installed on the gravel layer 44 side of the treatment tank 48, and the treated water recovery tank 49 is installed on the support layer 47 side.
The pipe height of the treated water recovery tank 49 relative to the surface of the treated water in the treated water storage tank 43 is adjusted so that the treated water level (flow rate) flowing through the treated tank 48 is constant, A water storage tank 43 and a treated water collection tank 49 were installed.
Moreover, the sampling pipe 40 was installed in each layer. The sampling pipe 40 is formed by making a 0.2 mm hole on the surface of a resin tube having an inner diameter of 2 cm.

Next, as the treatment target water, a perfluorooctanoic acid (PFOA) solution having a concentration of 200 ppb was placed in the treatment target water raw water tank 41 and circulated from the gravel layer 44 side into the treatment tank at a flow rate of 2 L / hour.

The water to be treated after passing through each layer was collected from the sampling pipe, and the residual concentration of PFOA in the collected solution was measured.
The PFOA concentration was measured using a liquid chromatograph-tandem mass spectrometer (LC / MS / MS) manufactured by Waters Corporation under the following conditions.
-HPLC system main body: 2695 separation module-Mobile phase solvent: acetonitrile 45 vol% / 0.15% acetic acid aqueous solution 55 vol%
-HPLC column: Atlantis dC18 3 μm 2.1 × 30 mm
・ Tandem quadrupole mass spectrometer: Quattro micro API
(C7F15- having a molecular ion mass number of 369 was measured as a monitor ion.)
The measurement results are shown in Table 1.
In Table 1, S1 is raw water, S2 is after passing through the gravel layer 44, S3 is after passing through the support layer 45, S4 is the PFOA concentration of the PFOA solution after passing through the treatment layer 46, and S5 is treated water in the treated water recovery tank 49. Of PFOA.

According to the treatment method of the present invention, the fluorine-containing surfactant can be efficiently removed from the water to be treated without the treatment agent flowing out.

1 Conventional treatment layer 2, 35 Underground 3 Activated carbon 11, 13, 25, 27, 32, 34, 45, 47 Support layer 12, 26, 33, 46 Treatment layer 21, 41 Water source water tank 22, 42 Pump 23 to be treated , 43 Treated water storage tanks 24, 44 Gravel layers 28, 48 Treated tanks 29, 49 Treated water collection tank 31 Permeation wall 40 Sampling pipe 50 Membrane filter A Flow direction of groundwater B Flow direction of treated water S Processed water Water level

Claims (3)

A treatment method for removing a fluorine-containing surfactant from water to be treated containing a fluorine-containing surfactant,
Having the step of bringing the water to be treated into contact with the treatment agent,
The treatment agent is a particle on which powdered activated carbon is supported, and constitutes a treatment layer sandwiched between a pair of support layers,
The support layer is made of support particles,
An effective diameter of the support agent particles is −0.5 mm to +0.5 mm which is an effective diameter of the treatment agent. The processing method according to claim 1, wherein the effective diameter of the support agent particles is −0.3 mm to 0 mm of the effective diameter of the treatment agent. The processing method according to claim 1 or 2, wherein the effective diameter of the support particles is 0.3 to 1.3 mm.

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