JP2018118192A - Water treatment system and method - Google Patents

Abstract

A water treatment system using polylactic acid porous particles and a water treatment method using the system are provided. A raw water tank 11 into which raw water containing anions of inorganic compounds other than sulfate ions and sulfate ions is introduced, a barium tank 12 holding a barium aqueous solution containing barium ions, and the raw water tank 11 are introduced. A mixed liquid of the raw water and the barium aqueous solution mixed therewith is introduced, and a first muddy water treatment device 13 for separating the barium sulfate and the first supernatant liquid contained in the mixed liquid, and the first A water treatment system 10 comprising an adsorption tank 14 into which a supernatant liquid is introduced, and a chemical tank 15 that holds a chemical liquid containing polylactic acid porous particles. [Selection] Figure 1

Description

  The present invention relates to a water treatment system and a water treatment method.

Oxide ions such as selenium, arsenic, and chromium may be contained in wastewater from chemical establishments and construction sites. These anions are highly soluble, depending on inorganic flocculants such as sulfuric acid bands (aluminum sulfate) and PAC (polyaluminum chloride) used in conventional general wastewater treatment, and organic flocculants containing polymer polymers. It is difficult to precipitate and remove. Therefore, in Patent Document 1, selenium, arsenic, and chromium are added to an iron oxide mineral called _{Schwertmannite} [composition formula: Fe ₈ O ₈ (OH) _8-2x (SO ₄ ) _x ; 1 ≦ x ≦ 1.75]. Adsorption methods have been proposed.

JP 2005-95732 A

As a result of intensive studies by the present inventors, the Schwertmannite described in Patent Document 1 inherently contains sulfate ions, so that it is necessary to replace the sulfate ions in order to sufficiently adsorb the target anions. It was thought that there was. In addition, since the binding force of sulfate ions is relatively strong, it has been found that the efficiency of adsorbing the target anion to Schwertmannite is not necessarily high. Moreover, there is a problem that it is difficult to obtain the high-quality iron oxide mineral described in Patent Document 1 to the extent that a large amount of waste water can be treated.
Therefore, the present inventors have examined various minerals exhibiting better adsorption efficiency. Polylactic acid porous particles are relatively easily available and exhibit excellent adsorption efficiency for the target anion. I found. However, since polylactic acid porous particles easily adsorb sulfate ions, when polylactic acid porous particles are introduced into an aqueous solution in which sulfate ions and anions other than sulfate ions coexist, adsorption of anions other than sulfate ions does not occur. There was a problem that was hindered by sulfate ions.

  The present invention has been made in view of the above circumstances, and provides a water treatment system using polylactic acid porous particles and a water treatment method using the system.

[1] A raw water tank in which raw water containing sulfate ions and anions of inorganic compounds other than sulfate ions is introduced, a barium tank holding a barium aqueous solution containing barium ions, and the barium aqueous solution from the barium tank to the raw water. A first mixed liquid of a barium supply unit to be supplied to the water tank, the raw water introduced into the raw water tank, and the barium aqueous solution mixed therewith is introduced, and the barium sulfate contained in the first mixed liquid and the first A first turbid water treatment apparatus for separating one supernatant liquid, a first mixed liquid feeding section for feeding the first mixed liquid from the raw water tank to the first turbid water treatment apparatus, and the first supernatant liquid. Holds an adsorption tank into which the first supernatant is fed, a first supernatant liquid feeding section for feeding the first supernatant liquid from the first turbid water treatment device to the adsorption tank, and a chemical liquid containing polylactic acid porous particles A chemical tank Water treatment system, characterized in that the serial chemical and a chemical liquid supply section for supplying to the adsorption vessel from the chemical tank.
[2] A second mixed liquid of the first supernatant liquid introduced into the adsorption tank and the chemical liquid mixed therewith is introduced, and the polylactic acid porous particles contained in the second mixed liquid and the first liquid mixture A second turbid water treatment apparatus for separating two supernatant liquids, and a second mixed liquid feeding part for feeding the second mixed liquid from the adsorption tank to the second turbid water treatment apparatus. The water treatment system according to [1].
[3] A third storage tank that holds a flocculant that aggregates the barium sulfate and polylactic acid porous particles, and a first flocculant supply that supplies the flocculant from the third storage tank to the first muddy water treatment apparatus. And a flocculant second supply unit for supplying the flocculant from the third storage tank to the second turbid water treatment apparatus.
[4] A discharge tank that receives and temporarily stores the second supernatant liquid, and a second supernatant liquid supply section that supplies the second supernatant liquid from the second muddy water treatment apparatus to the discharge tank. And the water treatment system according to [2] or [3].
[5] A mud storage tank that receives the sediment containing the polylactic acid porous particles from the second muddy water treatment apparatus, and a second sediment transfer that transfers the precipitate from the second muddy water treatment apparatus to the mud storage tank. And a first sediment transfer section for transferring the barium sulfate from the first muddy water treatment device to the mud storage tank, according to any one of [2] to [4]. Water treatment system.
[6] A dehydrator for dehydrating at least one of the barium sulfate and the precipitate, and a third precipitate transfer unit for transferring at least one of the barium sulfate and the precipitate from the mud tank to the dehydrator. And a water treatment system according to [5].
[7] A water treatment method using the water treatment system according to any one of [1] to [6], wherein the raw water is introduced into the raw water tank, and the barium aqueous solution is added to the barium tank. Supplying the raw water tank to the raw water tank, mixing the raw water and the barium aqueous solution in the raw water tank, introducing the first mixed liquid into the first muddy water treatment device, and containing the barium sulfate contained in the first mixed liquid And the first supernatant liquid, the step of introducing the first supernatant liquid into the adsorption tank, the step of supplying the chemical liquid from the chemical tank to the adsorption tank, and the adsorption tank Mixing the first supernatant liquid and the chemical liquid, and adsorbing the anions of the inorganic compound to the polylactic acid porous particles contained in the chemical liquid in the obtained second liquid mixture. A water treatment method characterized by the above.
[8] First step of obtaining a primary treatment liquid in which the concentration of free sulfate ions is reduced by adding barium ions to raw water containing sulfate ions and anions of inorganic compounds other than sulfate ions to produce barium sulfate. And the primary treatment liquid is brought into contact with the polylactic acid porous particles so that the anion of the inorganic compound is adsorbed to the polylactic acid porous particles, and the concentration of the anion of the inorganic compound is reduced. And a second step of obtaining a water treatment method.
[9] A raw water tank into which raw water containing anions of inorganic compounds other than sulfate ions and sulfate ions is introduced, a barium tank holding a barium aqueous solution containing barium ions, and the barium aqueous solution from the barium tank to the raw water. A barium supply unit for supplying to the water tank; an adsorption tank into which the first mixed liquid of the raw water introduced into the raw water tank; and the barium aqueous solution mixed therein is introduced; and the first mixed liquid as the raw water. A first liquid mixture feeding section for feeding liquid from a water tank to the adsorption tank, a chemical tank for holding a chemical liquid containing polylactic acid porous particles, and a chemical liquid supply section for supplying the chemical liquid from the chemical tank to the adsorption tank A water treatment system comprising:
[10] Barium sulfate and polylactic acid porous particles contained in the second mixed solution, wherein a second mixed solution of the first mixed solution introduced into the adsorption tank and the chemical solution mixed therewith is introduced. And a second turbid water treatment apparatus for separating the second supernatant liquid, and a second mixed liquid feeding section for feeding the second mixed liquid from the adsorption tank to the second turbid water treatment apparatus. [9] The water treatment system according to [9].
[11] A third storage tank that holds a flocculant that aggregates the barium sulfate and polylactic acid porous particles, and a second flocculant supply that supplies the flocculant from the third storage tank to the second muddy water treatment apparatus. And a water treatment system according to [10].
[12] A discharge tank that receives and temporarily stores the second supernatant liquid, and a second supernatant liquid supply section that supplies the second supernatant liquid from the second muddy water treatment apparatus to the discharge tank. And the water treatment system according to [10] or [11].
[13] A mud storage tank for receiving a precipitate containing the barium sulfate and polylactic acid porous particles from the second muddy water treatment apparatus, and a second for transferring the precipitate from the second muddy water treatment apparatus to the mud storage tank. A water treatment system according to any one of [10] to [12], comprising a sediment transfer unit.
[14] The water according to [13], further comprising: a dehydrator that dehydrates the precipitate; and a third precipitate transfer unit that transfers the precipitate from the mud tank to the dehydrator. Processing system.
[15] A water treatment method using the water treatment system according to any one of [9] to [14], wherein the raw water is introduced into the raw water tank, and the barium aqueous solution is added to the barium tank. Supplying the raw water tank to the raw water tank, mixing the raw water and the barium aqueous solution in the raw water tank, introducing the formed first mixed liquid containing barium sulfate to the adsorption tank, and the chemical liquid to the chemical The step of supplying from the tank to the adsorption tank, the first mixed liquid and the chemical liquid are mixed in the adsorption tank, and the polylactic acid porous particles contained in the chemical liquid in the obtained second mixed liquid And a step of adsorbing anions of the inorganic compound.

  According to the water treatment system and the water treatment method of the present invention, among the sulfate ions contained in the raw water (treated water) and the anions of other inorganic compounds, the anions of the inorganic compounds are converted into polylactic acid porous particles. It is possible to obtain water in which the concentration of the anion is reduced. Moreover, since the polylactic acid porous particle can be easily chemically synthesized, it can be easily obtained.

It is a mimetic diagram of water treatment system 10 of an example of the present invention. It is a schematic diagram of the water treatment system 1 of an example of this invention. 2 is an adsorption isotherm of selenate ions in polylactic acid porous particles.

<< Water treatment system; First aspect >>
A water treatment system 10 which is an example of the water treatment system of the first aspect of the present invention is shown in FIG.
The water treatment system 10 includes a raw water tank 11 into which raw water containing sulfate ions and anions of inorganic compounds other than sulfate ions is introduced, a barium tank 12 holding a barium aqueous solution containing barium ions, and the barium aqueous solution as barium aqueous solution. And a barium supply unit 12a for supplying the raw water tank 11 from the tank 12.
Further, the water treatment system 10 is introduced with a first mixed liquid of the raw water introduced into the raw water tank 11 and the barium aqueous solution mixed therewith, and the barium sulfate and the first mixed liquid contained in the first mixed liquid are introduced. A first turbid water treatment device 13 for separating the supernatant from the first liquid mixture, a first mixed liquid feeding portion 11a for feeding the first mixed solution from the raw water tank 11 to the first turbid water treatment device 13, and the first supernatant. An adsorbing tank 14 into which the liquid is introduced, and a first supernatant liquid feeding section 13a that feeds the first supernatant liquid from the first muddy water treatment device 13 to the adsorption tank 14.
Further, the water treatment system 10 includes a chemical tank 15 that holds a chemical liquid containing polylactic acid porous particles, and a chemical liquid supply unit 15 a that supplies the chemical liquid from the chemical tank 15 to the adsorption tank 14.
The barium supply unit 12a, the first mixed liquid supply unit 11a, the first supernatant liquid supply unit 13a, and the chemical solution supply unit 15a are each configured by a known connection member such as a pipe, a valve, or a pump.

In the water treatment system 10, a second mixed liquid of the first supernatant liquid introduced into the adsorption tank 14 and the chemical liquid mixed therewith is introduced, and the polylactic acid porous material contained in the second mixed liquid A second muddy water treatment device 18 that separates the particles from the second supernatant is provided as an optional configuration.
Connected to the second muddy water treatment device 18 is a second liquid mixture feeding portion 14a for feeding the second mixed solution containing polylactic acid porous particles from the adsorption tank 14 to the second muddy water treatment device 18. ing.

  In addition to the above, the water treatment system 10 is supplied to the first muddy water treatment device 13 and the second muddy water treatment device 18, and a third storage tank 20 holding a flocculant for aggregating barium sulfate and polylactic acid porous particles, respectively. A discharge tank 19 for receiving the second supernatant and temporarily storing the second supernatant until it is discharged to the outside; from the first muddy water treatment device 13 and the second muddy water treatment device 18; And a dewatering device 22 for dehydrating the precipitate, which are provided as optional components, and a mud storage tank 21 for receiving a precipitate containing polylactic acid porous particles, respectively.

The first muddy water treatment device 13 is connected to a first coagulant supply unit 20 a that supplies the flocculant from the third storage tank 20 to the first muddy water treatment device 13.
The second muddy water treatment device 18 is connected to a second coagulant supply unit 20b that supplies the coagulant from the third storage tank 20 to the second muddy water treatment device 18.
Connected to the discharge tank 19 is a second supernatant liquid supply section 18 a for supplying the second supernatant liquid from the second muddy water treatment device 18 to the discharge tank 19.
Connected to the mud storage tank 21 is a first sediment transfer section 13 b for transferring the barium sulfate precipitate from the first muddy water treatment device 13 to the mud storage tank 21.
Connected to the mud storage tank 21 is a second sediment transfer section 18 b for transferring a precipitate containing polylactic acid porous particles from the second muddy water treatment device 18 to the mud storage tank 21.
Connected to the dehydrator 22 is a third precipitate transfer section 21 a that transfers at least one of the precipitate containing barium sulfate and the polylactic acid porous particles from the mud storage tank 21 to the dehydrator 22.
Each part which performs said connection is comprised by well-known connection members, such as piping, a valve, and a pump.

<< Water treatment method; Second embodiment >>
In the water treatment method of the second aspect of the present invention, using the water treatment system of the first aspect described above, among the anions of inorganic compounds other than sulfate ions and sulfate ions contained in raw water (treated water), In this method, the anion of the inorganic compound is efficiently reduced by polylactic acid porous particles. By this water treatment method, clean treated water is obtained.
Further, according to this method, since the primary treated water having a reduced concentration of sulfate ions is brought into contact with the polylactic acid porous particles, the anions of the inorganic compound are converted into the polylactic acid porous particles without being subjected to competition by sulfate ions. Can be adsorbed. As a result, the amount of polylactic acid porous particles used can be reduced.
Below, the method using the water treatment system 10 is demonstrated.

First, raw water containing anions of inorganic compounds other than sulfate ions and sulfate ions is introduced into the raw water tank 11.
Next, the barium aqueous solution is supplied from the barium tank 12 to the raw water tank 11 via the barium supply unit 12a. By mixing the raw water and the barium aqueous solution in the raw water tank 11, barium sulfate is generated in the first mixed solution. At this time, tap water may be supplied to the raw water tank 11 as necessary. Subsequently, the first mixed liquid containing barium sulfate is introduced from the raw water tank 11 to the first muddy water treatment device 13 through the first mixed liquid feeding section 11a.

  The said 1st liquid mixture introduce | transduced into the water tank of the 1st muddy water processing apparatus 13 is left still, and the precipitation containing a barium sulfate is settled. When a flocculant (for example, polyaluminum chloride, polymer flocculant, etc.) is supplied from the third storage tank 20 to the first muddy water treatment device 13 via the flocculant first supply unit 20a, sedimentation of the precipitate is promoted. Can do. After the sedimentation, the first supernatant liquid separated from barium sulfate is fed to the adsorption tank 14 via the first supernatant liquid feeding section 13a.

  The first supernatant liquid fed to the adsorption tank 14 still contains anions of inorganic compounds other than sulfate ions. On the other hand, since barium sulfate has low solubility in water, most barium sulfate is separated as a precipitate.

  The sediment containing the precipitated barium sulfate is treated as sludge and transferred from the first muddy water treatment device 13 to the mud storage tank 21 via the first sediment transfer section 13b and temporarily stored. Thereafter, the sludge is transferred from the mud storage tank 21 to the dewatering device 22 such as a filter press through the third sediment transfer section 21a, and the sludge is dehydrated to obtain a dehydrated cake containing barium sulfate. The dehydrated cake is properly disposed of by known methods.

  Next, a chemical liquid containing polylactic acid porous particles is introduced from the chemical tank 15 to the adsorption tank 14 via the chemical liquid supply unit 15a, and the first supernatant liquid and the chemical liquid are mixed. Thereby, the anion of the said inorganic compound contacts the polylactic acid porous particle in the adsorption tank 14, and adsorb | sucks. Then, the 2nd liquid mixture containing a polylactic acid porous particle is transferred from the adsorption tank 14 to the 2nd muddy water processing apparatus 18 via the 2nd liquid mixture sending part 14a. As a dispersion medium of polylactic acid porous particles in the chemical solution, for example, water is preferable.

  The said 2nd liquid mixture introduce | transduced into the water tank of the 2nd muddy water processing apparatus 18 is left still, and the precipitation containing a polylactic acid porous particle is settled. When the flocculant (for example, polyaluminum chloride, polymer flocculant, etc.) is supplied from the third storage tank 20 to the second muddy water treatment device 18 via the flocculant second supply unit 20b, sedimentation of the precipitate is promoted. Can do. After the precipitate containing polylactic acid porous particles settles, the second supernatant liquid in which the anion concentration of the inorganic compound is reduced is transferred to the discharge tank 19 via the second supernatant liquid feeding part 18a. Temporarily store and discharge to the outside of the river etc. at an appropriate timing. Moreover, you may return a 2nd supernatant liquid to the raw | natural water tank 11 as needed.

  The sediment containing the precipitated polylactic acid porous particles is treated as sludge and transferred from the second muddy water treatment device 18 to the mud storage tank 21 via the second sediment transfer section 18b and temporarily stored. Thereafter, the sludge is transferred from the mud storage tank 21 to the dewatering device 22 such as a filter press through the third sediment transfer section 21a, and the sludge is dehydrated to obtain a dehydrated cake containing polylactic acid porous particles. The dehydrated cake is properly disposed of by known methods.

  In the water treatment method described above, the sulfate ion removal method, the anion adsorption method, and the polylactic acid porous particle synthesis method described below can be applied.

[Sulfate ion removal method]
In the raw water tank 11, barium sulfate can be produced by bringing raw water containing sulfate ions and anions of inorganic compounds other than sulfate ions into contact with barium ions.
Examples of the method of bringing the raw water and barium ions into contact with the raw water tank 11 include a method of directly adding a barium salt and a method of adding a barium aqueous solution containing a barium salt.

Examples of the barium salt include one or more barium salts selected from barium chloride and barium hydroxide.
These barium salts are less likely to hinder the adsorption of anions of the inorganic compound by the polylactic acid porous particles. Here, the anion of the inorganic compound is preferably an anion other than the counter anion constituting the barium salt.

  Of the above barium salts, barium chloride is particularly preferred. The adsorptive power of chloride ions to polylactic acid porous particles is lower than that of other anions such as inorganic oxoacid ions. For this reason, in the adsorption of anions to the polylactic acid porous particles, competition by chloride ions hardly occurs, and barium ions can be added to the aqueous solution.

  The density | concentration of the said barium salt contained in the said barium aqueous solution is not specifically limited, For example, it can be set as about 0.1-3.0M.

The pH of the barium aqueous solution is not particularly limited as long as it is a pH at which barium sulfate is generated when mixed with raw water, and examples thereof include pH 1 to 7. Within this pH range, the pH of the mixed solution obtained by mixing with raw water and the first supernatant thereof is likely to be 1 to 7, and the anion adsorption efficiency by the polylactic acid porous particles in the subsequent stage is increased, which is preferable.
The method for adjusting the pH of the raw water is not particularly limited, and examples thereof include a method of adding hydrochloric acid and sodium hydroxide.

The temperature of the barium aqueous solution when mixed with the raw water is not particularly limited, and examples thereof include 10 to 40 ° C.
The amount of the barium aqueous solution to be mixed with the raw water is not particularly limited, and may be set according to the concentration of sulfate ions contained in the raw water. It is preferable to mix. That is, it is preferable to mix the barium aqueous solution with the raw water so that the barium ion / sulfate ion molar ratio is 1 or more. When barium ions are mixed in the above amounts, most of the sulfate ions contained in the raw water can be removed as barium sulfate.

  The object of generating barium sulfate can be achieved even when a method of adding a barium salt directly to the raw water tank 11 is employed instead of the method of adding the barium aqueous solution as described above. However, the operation is easier when the barium salt is added as a barium aqueous solution than when it is added as a solid. Furthermore, it is preferable because undissolved barium salt in the raw water tank 11 is prevented and the concentration of the barium salt in the raw water tank 11 is easily controlled.

[Anion adsorption method]
In the adsorption tank 14, the anion can be adsorbed to the polylactic acid porous particles by bringing the first supernatant liquid containing anions of inorganic compounds other than sulfate ions into contact with the polylactic acid porous particles.

  Examples of the inorganic compound include inorganic compounds containing inorganic elements such as selenium, arsenic, chromium, fluorine, and phosphorus. Specific examples include selenium, arsenic, chromium oxo acid, hydrofluoric acid (hydrofluoric acid), phosphoric acid, and the like.

  The inorganic compound is preferably an oxo acid from the viewpoint of exhibiting a high adsorptive power to polylactic acid porous particles, and more preferably a monovalent or divalent anion of an inorganic oxo acid containing the inorganic element. Here, the oxo acid is an inorganic compound in which a hydroxyl group (—OH) and an oxo group (═O) are bonded to one inorganic atom, and a proton of the hydroxyl group can be eliminated. Oxo acid can be an oxo acid ion from which the proton is eliminated in water.

As the oxo acid, selenium oxo acid is preferable from the viewpoint of exhibiting high adsorbing power on polylactic acid porous particles, and selenium oxo acid ions include selenate ions (SeO ₄ ²⁻ ), selenate hydrogen ions ( HSeO ₄ ⁻ ), selenite ion (SeO ₃ ²⁻ ), and hydrogen selenite ion (HSeO ₃ ⁻ ).

  The anion of the inorganic compound contained in the raw water and the first supernatant may be one type or two or more types.

  In the present invention, the polylactic acid porous particles used as an adsorbent for the anions of the inorganic compound are not particularly limited as long as they have fine pores small enough to adsorb the anions of the inorganic compound. The average pore diameter of the fine pores of the polylactic acid porous particles is preferably 0.001 μm to 5 μm, more preferably 0.001 μm to 1 μm, and more preferably 0.001 μm to 0.5 μm. When the porous structure of the polylactic acid porous particles has the above-described preferable micropores, the anion of the inorganic compound is easily trapped physically or chemically in the microspace. Moreover, the porous structure of the polylactic acid porous particles having the above-mentioned preferable micropores is preferable because it provides a large surface area capable of adsorbing anions of inorganic compounds as in the case of activated carbon.

  In the present invention, when the first supernatant liquid is brought into contact with the polylactic acid porous particles, the anion of the inorganic compound contained in the first supernatant liquid is trapped and adsorbed by the porous structure of the polylactic acid porous particles. I think that.

  The pH of the polylactic acid porous particle dispersion during the treatment when the anions of inorganic compounds other than sulfate ions are adsorbed to the polylactic acid porous particles contained in the first supernatant is preferably 4 or more and 9 or less, 4 or more and 7 or less are more preferable, and acidity of 4 or more and 6 or less is more preferable. The method for adjusting the pH of the polylactic acid porous particle dispersion is not particularly limited, and examples thereof include a method of adding hydrochloric acid and sodium hydroxide.

When the pH of the polylactic acid porous particle dispersion is 4 or more and 7 or less, hydrolysis of the polylactic acid porous particles can be suppressed, and the anion adsorption force of the inorganic compound by the polylactic acid porous particles can be further increased. it can.
If the polylactic acid porous particles are on the weakly acidic side, the mechanism by which the adsorptive power of the anion of the inorganic compound is further increased is unknown, but the following is considered as a factor. That is, (1) pH affects the porous structure, (2) A part of the ester bond constituting the main chain of polylactic acid is cleaved during the formation of the porous structure, and the carboxyl produced by the cleavage It is conceivable that the elimination of the proton of the group and the hydroxyl group (formation of a negative charge) is suppressed.

In the polylactic acid porous particle dispersion, the temperature at which the anions of the inorganic compound are adsorbed to the polylactic acid porous particles is not particularly limited, and is preferably 4 to 40 ° C, more preferably 4 to 30 ° C, for example. -20 ° C is more preferable.
When the temperature is within the above range, the anion adsorption force of the inorganic compound by the polylactic acid porous particles can be increased. When the temperature is not less than the lower limit of the above temperature range, the diffusion rate of the anion of the inorganic compound in the polylactic acid porous particle dispersion increases, and the efficiency of contacting and adsorbing the polylactic acid porous particles is further increased. When the temperature is not more than the upper limit of the above temperature range, hydrolysis of the polylactic acid porous particles can be suppressed, and the anion adsorption force of the inorganic compound by the polylactic acid porous particles can be increased.

The amount of polylactic acid porous particles in contact with the first supernatant liquid is not particularly limited with respect to the content of the target anion contained in the first supernatant liquid. It may be set to an amount that is confirmed to sufficiently adsorb the anions.
Usually, if the amount of polylactic acid porous particles to be contacted is increased, the amount of anions that can be adsorbed also increases. For example, the adsorption amount of inorganic oxoacid ions by polylactic acid porous particles is 0.45 to 1.5 mol. / Kg.

  Examples of a method for recovering the polylactic acid porous particles having adsorbed anions from the first supernatant include a precipitation method and a filtration method. Examples of the precipitation method include a method in which the first supernatant is allowed to settle and a method in which the sulfuric acid band, PAC, polymer polymer flocculant and the like are added to the first supernatant to cause aggregation to precipitate. Can be mentioned. Thereafter, the treatment liquid is obtained as a supernatant liquid of the precipitated polylactic acid porous particles or a filtrate obtained by filtering the precipitated polylactic acid porous particles.

  When an adsorption method is adopted in which a polylactic acid porous particle powder is packed into a column and raw water is allowed to flow into this column, the polylactic acid porous particle adsorbs the anion of the inorganic compound and removes the anion. The treated liquid can be obtained by flowing out of the column.

  In the water treatment method described above, an anion adsorbent having polylactic acid porous particles can be used as the main component of the adsorbent. Here, “main component” means a component having the largest adsorption amount when the adsorption amount of the target anion between the components of the adsorbent is compared. This anion adsorbent may further have a holding member for holding an adsorbent (polylactic acid porous particles).

  The shape of the polylactic acid porous particles as the adsorbent is not particularly limited, and may be a spherical shape, a spheroid shape, or any other indefinite shape. A polylactic acid porous particle dispersion (suspension) in which polylactic acid porous particles of these shapes are dispersed in a solvent such as water can also be used as an adsorbent.

  Examples of the holding member include containers, columns (cylinders), baskets, nets, and the like that hold polylactic acid porous particles inside. In addition, a holding member capable of fixing the polylactic acid porous particles on the surface can also be employed, and examples thereof include a form in which the polylactic acid porous particles are fixed on the surface of the plate material.

《Synthesis of polylactic acid porous particles》
The polylactic acid porous particles used in the present invention are those chemically synthesized by a known method, and those obtained by the method for producing polylactic acid porous particles disclosed in JP-A-2009-242728 are preferable.

  In the method for producing polylactic acid porous particles described in the above publication, (i) polylactic acid and a first solvent which is a good solvent for polylactic acid are mixed, and the mixture is heated to melt polylactic acid. And (ii) a cooling step of cooling the melt obtained by the melting step at a temperature at which polylactic acid crystallizes or solidifies. This production method further includes (iii) a separation step of separating polylactic acid crystals from the melt after the cooling step, and (iv) polylactic acid crystals obtained by the separation step, and the solubility of polylactic acid. It is preferable to have a washing step of contacting a second solvent having a high solubility of the first solvent to wash the polylactic acid crystals, and (v) a drying step of drying the polylactic acid crystals after the washing step.

  According to the above production method, for example, the average particle size is 99 to 700 μm, the average pore size of the pores constituting the porous structure is about 0.27 μm to 1.4 μm, and the variation coefficient of the pore size is 25% or less. Thus, polylactic acid porous particles having a crystallinity of 50% or more can be easily obtained.

  Here, the “particle diameter” of the polylactic acid porous particles is the diameter of the maximum inscribed circle with respect to the two-dimensional shape of the polylactic acid porous particles observed with an electron microscope. For example, when the two-dimensional shape of polylactic acid porous particles is a shape that is reasonable to approximate a circle (when it is closer to a circle than other shapes), the diameter of the circle is the particle diameter and approximates an ellipse When it is appropriate to do so, the minor axis of the ellipse is the particle diameter, and when it is reasonable to approximate a square, the length of the side of the square is the particle diameter, and when it is reasonable to approximate the rectangle The length of the short side of the rectangle is the particle diameter. The “average particle size” is obtained by observing and measuring the particle size of a plurality of randomly selected particles with an electron microscope and calculating the average value. The number of particles to be measured is not particularly limited, but is preferably 20 or more, for example.

The coefficient of variation of the particle diameter of the group of polylactic acid porous particles is calculated by the equation of standard deviation of observed particle diameter ÷ average value × 100 (%), and the smaller the value, the more uniform the particle diameter is shown. .
The coefficient of variation of the group of polylactic acid porous particles used in the present invention is preferably 25% or less, preferably 20% or less, and more preferably 15% or less. By using polylactic acid porous particles having a uniform particle diameter, stable and homogeneous adsorption performance can be obtained.

  The “pore diameter” of the polylactic acid porous particle is the diameter of the maximum inscribed circle with respect to the opening shape of the hole. For example, when the opening shape of the hole is a shape that is reasonable to approximate a circle (from other shapes) Is the diameter of the circle), if it is reasonable to approximate an ellipse, the minor axis of the ellipse, and if it is reasonable to approximate a square, the length of the side of the square If it is reasonable to approximate a rectangle, it is the length of the short side of the rectangle. The “average pore diameter” is obtained by observing and measuring the pore diameters of a plurality of randomly selected holes with a microscope and calculating the average value. The number of holes to be measured is not particularly limited, but is preferably 20 or more, for example.

The variation coefficient of the pore diameter of the pores constituting the porous structure of the polylactic acid porous particle is calculated by the equation of standard deviation of observed pore diameter ÷ average value × 100 (%), and the smaller the value, the more uniform the pore diameter. It is a porous particle.
The coefficient of variation of the polylactic acid porous particles used in the present invention is preferably 45% or less, preferably 35% or less, and more preferably 25% or less. By using polylactic acid porous particles having a uniform pore size, stable and homogeneous adsorption performance can be obtained.

The crystallinity of the polylactic acid porous particles can be measured by a differential scanning calorimetry method (DSC method). The DSC method can be performed, for example, by packing a sample of 5 to 10 mg in an aluminum pan and raising the temperature from room temperature to 150 ° C. at 5 ° C./min at 5 ° C./min while flowing a small amount of nitrogen in the DSC apparatus. . The crystallinity χc is obtained by the following equation.
(Expression) χc (%) = ΔHm ÷ ΔHf × 100
In the above formula, ΔHm represents the heat of fusion of the sample measured by the DSC apparatus, and ΔHf represents the equilibrium heat of fusion of 100% crystalline polylactic acid.
The crystallinity of the polylactic acid porous particles used in the present invention is preferably 50% or more, more preferably 60% or more. The higher the degree of crystallinity, the higher the mechanical strength such as toughness of the polylactic acid porous particles, and the easier the handling and operation when carrying out the anion adsorption method of the present invention.

  The sulfate ion removal method, the anion adsorption method, and the polylactic acid porous particle synthesis method described above can also be applied to the water treatment method described below.

<< Water treatment method; Third aspect >>
In the water treatment method of the third aspect of the present invention, barium ions are generated by adding barium ions to raw water containing inorganic ions other than sulfate ions and sulfate ions, and the concentration of free sulfate ions is reduced. A first step of obtaining the primary treatment liquid, and bringing the primary treatment liquid into contact with the polylactic acid porous particles so that the anion of the inorganic compound is adsorbed on the polylactic acid porous particles, and the anion of the inorganic compound And a second step of obtaining a secondary treatment liquid having a reduced concentration.

  By obtaining a primary treatment liquid having a reduced free sulfate ion concentration in the first step, the anion of the inorganic compound is adsorbed on the polylactic acid porous particles without being competed by sulfate ions in the second step. Thereby, the quantity of the polylactic acid porous particle used at a 2nd process can be reduced. In other words, since sulfate ions have a relatively high adsorptive power to polylactic acid porous particles, if the water to be treated contains sulfate ions, the polylactic acid porous particles are consumed by sulfate ions. However, in this water treatment method, the amount of polylactic acid porous particles used in the second step can be reduced by previously removing sulfate ions in the first step.

[First step]
The raw water in the first step is the same as the raw water in the water treatment method of the second aspect described above.
Examples of the method of adding barium ions to the raw water include a method of directly adding the barium salt exemplified in the above-described sulfate ion removing method and a method of adding the above-described barium aqueous solution containing the barium salt.

The amount of barium ions added to the raw water is preferably 50 parts by mole or more, more preferably 70 parts by mole or more, and still more preferably 120 parts by mole or more with respect to 100 parts by mole of the sulfate ion contained in the raw water.
If it is at least the lower limit of the above range, barium sulfate can be easily formed, and the free sulfate ion concentration in the raw water can be sufficiently reduced. The upper limit of the above range is not particularly limited, and may be, for example, about 200 parts by mole.

The pH of the raw water to which barium ions are added (primary treated water) is not particularly limited as long as it is a pH at which barium sulfate is generated, and can be performed in the range of pH 1 to 7, for example.
The method for adjusting the pH of the aqueous solution to the above range is not particularly limited, and examples thereof include a method of adding hydrochloric acid, sodium hydroxide or the like to raw water or primary treated water.

  The temperature of the raw water (primary treated water) to which barium ions have been added is not particularly limited as long as it is a temperature at which barium sulfate is generated, and can be performed, for example, in the range of 4 to 60 ° C.

  Barium sulfate is produced by adding barium ions to the raw water. Since the solubility of barium sulfate in water is low, precipitation of barium sulfate occurs. The presence of barium sulfate hardly hinders the adsorption of the anion of the inorganic compound to the polylactic acid porous particles in the second step of the latter stage. Therefore, the primary treatment liquid used in the second step may or may not contain barium sulfate, but from the viewpoint of increasing the dispersibility of the polylactic acid porous particles added to the primary treatment liquid. It is preferable to remove barium sulfate in advance.

  Examples of the method for removing barium sulfate from the primary treatment liquid include a precipitation method and a filtration method. Examples of the precipitation method include a method in which the aqueous solution is allowed to stand, and a method in which a sulfate band, PAC, a high molecular weight polymer flocculant, and the like are added to the aqueous solution to cause aggregation to precipitate.

[Second step]
By bringing the polylactic acid porous particles into contact with the primary treatment liquid, the anion of the inorganic compound contained in the primary treatment liquid can be adsorbed on the polylactic acid porous particles. This adsorption method is the same as the case of the anion adsorption method described above. When the anion of the inorganic compound is adsorbed on the polylactic acid porous particles, the polylactic acid porous particles adsorbing the anions are dispersed in the secondary treatment liquid having a reduced anion concentration.

  The method of bringing the primary treatment liquid into contact with the polylactic acid porous particles is not particularly limited. For example, the method of charging the primary treatment liquid with the powder of polylactic acid porous particles and stirring, the polylactic acid porous material held by the holding member For example, a method of flowing the primary treatment liquid over the particles may be used.

When an adsorption method in which the powder of polylactic acid porous particles is put into the primary treatment liquid and stirred is used, the polylactic acid porous particles adsorbing the anion of the inorganic compound are dispersed (secondary treatment liquid). Can be recovered from.
Examples of a method for recovering the polylactic acid porous particle powder from the secondary treatment liquid include a precipitation method and a filtration method. Examples of the precipitation method include a method in which the secondary treatment liquid is allowed to stand to precipitate, a method in which the secondary treatment liquid is added with sulfuric acid band, PAC, polymer polymer flocculant, and the like to cause aggregation to precipitate. . Thereafter, the secondary treatment liquid is obtained as a supernatant liquid of the precipitated polylactic acid porous particles or a filtrate obtained by filtering the precipitated polylactic acid porous particles.

  When an adsorption method is adopted in which a polylactic acid porous particle powder is packed into a column and the primary treatment liquid is allowed to flow into the column, the polylactic acid porous particle adsorbs the anion of the inorganic compound, and the anion It is possible to obtain the secondary treatment liquid from which the water has been removed by flowing it out of the column.

  In the water treatment method described above, an anion adsorbent having polylactic acid porous particles can be used as the main component of the adsorbent. Here, “main component” means a component having the largest adsorption amount when the adsorption amount of the target anion between the components of the adsorbent is compared. This anion adsorbent may further have a holding member for holding an adsorbent (polylactic acid porous particles).

  The shape of the polylactic acid porous particles as the adsorbent is not particularly limited, and may be a spherical shape, a spheroid shape, or any other indefinite shape. A polylactic acid porous particle dispersion (suspension) in which polylactic acid porous particles of these shapes are dispersed in a solvent such as water can also be used as an adsorbent.

  Examples of the holding member include containers, columns (cylinders), baskets, nets, and the like that hold polylactic acid porous particles inside. In addition, a holding member capable of fixing the polylactic acid porous particles on the surface can also be employed, and examples thereof include a form in which the polylactic acid porous particles are fixed on the surface of the plate material.

<< Water treatment system; Fourth aspect >>
The water treatment system 1 which is an example of the water treatment system of the 4th aspect of this invention is shown in FIG.
The water treatment system 1 to be described later is a water treatment system excluding the first muddy water treatment device 13 in the configuration of the water treatment system 10 described above.
The water treatment system 1 includes a raw water tank 11 into which raw water containing sulfate ions and anions of inorganic compounds other than sulfate ions is introduced, a barium tank 12 holding a barium aqueous solution containing barium ions, and the barium aqueous solution as barium aqueous solution. And a barium supply unit 12a for supplying the raw water tank 11 from the tank 12.
Further, the water treatment system 1 includes an adsorption tank 14 into which a first mixed liquid of the raw water introduced into the raw water tank 11 and the barium aqueous solution mixed therewith is introduced together with the formed barium sulfate, A first liquid mixture feeding section 11a for feeding the first liquid mixture from the raw water tank 11 to the adsorption tank 14.
Furthermore, the water treatment system 1 includes a chemical tank 15 that holds a chemical liquid containing polylactic acid porous particles, and a chemical liquid supply unit 15 a that supplies the chemical liquid from the chemical tank 15 to the adsorption tank 14.
The barium supply unit 12a, the first mixed liquid supply unit 11a, and the chemical solution supply unit 15a are each configured by a known connection member such as a pipe, a valve, or a pump.

Furthermore, the water treatment system 1 introduces a second mixed liquid of the first mixed liquid introduced into the adsorption tank 14 and the chemical liquid mixed therewith, and contains barium sulfate contained in the second mixed liquid. A second muddy water treatment device 18 for separating the polylactic acid porous particles and the second supernatant is provided.
Connected to the second muddy water treatment device 18 is a second liquid mixture feeding portion 14a for feeding the second mixed solution containing polylactic acid porous particles from the adsorption tank 14 to the second muddy water treatment device 18. ing.

  In addition to the above, the water treatment system 1 is supplied to the second turbid water treatment device 18, and a third storage tank 20 holding a flocculant for aggregating barium sulfate and polylactic acid porous particles; and the second supernatant liquid A discharge tank 19 for temporarily storing the second supernatant liquid until it is received and discharged to the outside; a mud storage tank for receiving a precipitate containing barium sulfate and polylactic acid porous particles from the second muddy water treatment device 18; 21; and a dewatering device 22 for dewatering the precipitate as an arbitrary configuration.

The second muddy water treatment device 18 is connected to a second coagulant supply unit 20b that supplies the coagulant from the third storage tank 20 to the second muddy water treatment device 18.
Connected to the discharge tank 19 is a second supernatant liquid supply section 18 a for supplying the second supernatant liquid from the second muddy water treatment device 18 to the discharge tank 19.
Connected to the mud storage tank 21 is a second sediment transfer section 18 b for transferring a precipitate containing barium sulfate and polylactic acid porous particles from the second muddy water treatment device 18 to the mud storage tank 21.
Connected to the dehydrator 22 is a third precipitate transfer section 21 a that transfers at least one of the precipitates containing barium sulfate and polylactic acid porous particles from the mud storage tank 21 to the dehydrator 22.
Each part which performs said connection is comprised by well-known connection members, such as piping, a valve, and a pump.

<< Water Treatment Method; Fifth Aspect >>
The water treatment method of the fifth aspect of the present invention uses the water treatment system of the fourth aspect described above, among sulfate ions and inorganic anions other than sulfate ions contained in raw water (treated water), In this method, the anion of the inorganic compound is efficiently reduced by polylactic acid porous particles. By this water treatment method, clean treated water is obtained.
In addition, according to the present method, the primary treated water having a reduced concentration of sulfate ions due to the formation of barium sulfate is brought into contact with the polylactic acid porous particles. Ions can be adsorbed on the polylactic acid porous particles. As a result, the amount of polylactic acid porous particles used can be reduced.
Below, the method using the water treatment system 1 is demonstrated.

First, raw water containing anions of inorganic compounds other than sulfate ions and sulfate ions is introduced into the raw water tank 11.
Next, the barium aqueous solution is supplied from the barium tank 12 to the raw water tank 11 via the barium supply unit 12a. By mixing the raw water and the barium aqueous solution in the raw water tank 11, barium sulfate is produced in the obtained first mixed liquid. At this time, tap water may be supplied to the raw water tank 11 as necessary. Subsequently, the first mixed liquid containing barium sulfate is introduced from the raw water tank 11 to the adsorption tank 14 through the first mixed liquid feeding section 11a.

  The first mixed liquid fed to the adsorption tank 14 still contains anions of inorganic compounds other than sulfate ions. On the other hand, since barium sulfate has low solubility in water, most barium sulfate is precipitated.

  Next, a chemical liquid containing polylactic acid porous particles is introduced from the chemical tank 15 to the adsorption tank 14 through the chemical liquid supply unit 15a, and the first mixed liquid and the chemical liquid are mixed to obtain the second mixed liquid. obtain. Thereby, in the 2nd liquid mixture in the adsorption tank 14, the anion of the said inorganic compound contacts polylactic acid porous particle, and it adsorb | sucks. Then, the 2nd liquid mixture containing a barium sulfate and a polylactic acid porous particle is transferred from the adsorption tank 14 to the 2nd muddy water processing apparatus 18 via the 2nd liquid mixture sending part 14a. As a dispersion medium of polylactic acid porous particles in the chemical solution, for example, water is preferable.

  The said 2nd liquid mixture introduce | transduced into the water tank of the 2nd muddy water processing apparatus 18 is left still, and the precipitation containing a barium sulfate and a polylactic acid porous particle is settled. When the flocculant (for example, polyaluminum chloride, polymer flocculant, etc.) is supplied from the third storage tank 20 to the second muddy water treatment device 18 via the flocculant second supply unit 20b, sedimentation of the precipitate is promoted. Can do. After the precipitate containing barium sulfate and polylactic acid porous particles settles, the second supernatant liquid in which the anion concentration of the inorganic compound is reduced is discharged to the discharge tank 19 via the second supernatant liquid feeding section 18a. Transport, store temporarily, and discharge to the outside of the river etc. at an appropriate timing. Moreover, you may return a 2nd supernatant liquid to the raw | natural water tank 11 as needed.

  The sediment containing the precipitated barium sulfate and polylactic acid porous particles is treated as sludge, transferred from the second muddy water treatment device 18 to the mud storage tank 21 via the second sediment transfer section 18b, and temporarily stored. Thereafter, the sludge is transferred from the mud storage tank 21 to the dewatering device 22 such as a filter press through the third sediment transfer section 21a, and the sludge is dehydrated to obtain a dehydrated cake containing polylactic acid porous particles. The dehydrated cake is properly disposed of by known methods.

  In the water treatment method of the fifth aspect described above, the sulfate ion removal method and the anion adsorption method described above (however, “first supernatant” can be read as “first mixed solution”). And a method of synthesizing polylactic acid porous particles can be applied.

[Synthesis of porous polylactic acid particles]
High purity poly L-lactic acid (molecular weight: 100,000 to 300,000) was added to diethyl phthalate in the ampule tube so as to have a concentration of 10% by mass. The air in the ampoule tube was replaced with nitrogen, and the ampoule tube was sealed with a gas burner. The ampoule tube was immersed in an oil bath at 160 ° C. for 10 minutes to melt the poly L-lactic acid, and water at 0 ° C. It was immersed in the bath for 20 minutes. This cooling produced polylactic acid particles in the ampoule tube.
The above particles were taken out from the ampule tube and collected by a filtration method. After washing by adding 1000 ml of methanol to about 10 g of the obtained particles, the particles were collected by a filtration method. The particles were dried by vacuum drying to obtain the desired polylactic acid porous particles.
A part of the produced polylactic acid porous particles was subjected to gold sputtering, observed with a scanning electron microscope (SEM), and the particle diameter thereof was measured.
As a result of the measurement, the produced polylactic acid porous particles had an average particle size of about 40 μm, a coefficient of variation of about 25%, an average pore size of about 0.4 μm, and a coefficient of variation of about 40%. It was.

[Test Example 1]
A sodium selenate aqueous solution (pH 6) containing 10 mg / L of selenium was prepared. The following experiment was conducted using the polylactic acid porous particles obtained by the above synthesis.
0.015, 0.025, 0.05, 0.1, 0.2, 0.5, 1.0 (unit: 0.015, 0.025, 0.05, 0.1, 0.2) are added to the aqueous solution containing selenate ions. (w / w%) at each concentration. After this aqueous solution was stirred at 20 ° C. for 1 hour, the polylactic acid porous particles were collected by filtration, and the selenate ion concentration of the filtrate from which the polylactic acid porous particles were removed was determined according to JIS K0102: 2013 “67. The hydride generation ICP emission spectroscopic analysis method.
By the above test, adsorption isotherms for the selenate ions of the polylactic acid porous particles were obtained (FIG. 3). From the results shown in FIG. 3, it was confirmed that the equilibrium concentration of dissolved selenate ions was reduced below the environmental standard (0.01 mg / L) by the addition of polylactic acid porous particles.

[Comparative Example 1]
Experiments were conducted in the same manner as in Test Example 1 except that commercially available crosslinked acrylic resin particles (average particle size of about 20 μm, non-porous) were used instead of the polylactic acid porous particles.
As a result, the selenate ion concentration of the aqueous solution was 10 mg / L, the same as before the test.

[Test Example 2]
An aqueous solution containing about 2.4 g (about 25 mmol / L) of sulfate ions and about 0.5 mg / L (about 0.0064 mmol / L) of selenate ions was prepared. 4 w / w% of the polylactic acid porous particles synthesized above were added to this aqueous solution, and the aqueous solution adjusted to pH 6 was stirred at 20 ° C. for 1 hour. Thereafter, the sulfate ion concentration contained in the supernatant of the aqueous solution was measured by an ion chromatograph, and the selenium concentration was measured by the above ICP emission spectroscopic analysis method.
As a result, the concentration of sulfate ion and selenate ion was lower than the concentration before the addition of polylactic acid porous particles, and was almost zero. From this, it is clear that the polylactic acid porous particles adsorbed sulfate ions and selenate ions. This aqueous solution was filtered to remove the polylactic acid porous particles to obtain an aqueous solution from which sulfate ions and selenate ions were removed.

[Test Example 3]
An aqueous solution containing sulfate ions and selenate ions at the same concentration as in Test Example 2 was prepared. When barium chloride dihydrate was added to this aqueous solution at about 6 g / L (about 28.1 mmol / L) and stirred, a white precipitate thought to be barium sulfate was formed (first step).
Subsequently, 0.7 w / w% of the synthesized polylactic acid porous particles were added to the aqueous solution containing the barium sulfate precipitate, and the aqueous solution adjusted to pH 6 was stirred at 20 ° C. for 1 hour (second step). . Thereafter, each concentration of sulfate ion and selenium contained in the supernatant of the aqueous solution was measured in the same manner as in Test Example 2.
As a result, the concentration of sulfate ion and selenate ion was lower than the concentration before the addition of polylactic acid porous particles, and was almost zero.
In comparison with Test Example 2 and Test Example 3, the amount of polylactic acid porous particles required to remove selenate ions was 3.3 w / w% less in Test Example 2.

[Test Example 4]
An aqueous solution containing sulfate ions and selenate ions at the same concentration as in Test Example 2 was prepared. After adding 0.7 w / w% of the synthesized polylactic acid porous particles to this aqueous solution and stirring the aqueous solution adjusted to pH 6 at 20 ° C. for 1 hour, the concentration of selenium contained in the supernatant of the aqueous solution was tested. Measurement was performed in the same manner as in 2.
As a result, the concentration of selenate ions was only a few percent lower than the concentration before the addition of polylactic acid porous particles, and 90% or more remained in the supernatant and dissolved. The reason for this is considered that the dissolved amount of sulfate ions with respect to the amount of polylactic acid porous particles added to the aqueous solution was excessive, and most of the polylactic acid porous particles were consumed by the adsorption of sulfate ions.

  From the above results, it is clear that the water treatment system according to the present invention can obtain treated water from which the target anion is removed by bringing the anion of the inorganic compound into contact with the polylactic acid porous particles in the adsorption tank. is there.

  The configurations and combinations thereof in the embodiments described above are examples, and additions, omissions, substitutions, and other modifications of known configurations are possible without departing from the spirit of the present invention.

  The present invention can be widely applied to uses for purifying contaminated water containing heavy metals such as selenium, arsenic, and chromium.

DESCRIPTION OF SYMBOLS 10 ... Water treatment system, 11 ... Raw water tank, 11a ... 1st liquid mixture feed part, 12 ... Barium tank, 12a ... Barium supply part, 13 ... 1st muddy water processing apparatus, 13a ... 1st supernatant liquid feed part , 13b ... first sediment transfer section, 14 ... adsorption tank, 14a ... second mixed liquid feeding section, 15 ... chemical tank, 15a ... chemical supply section, 18 ... second muddy water treatment device, 18a ... second supernatant Liquid feeding section, 18b ... second sediment transfer section, 19 ... release tank, 20 ... third storage tank, 20a ... flocculant first supply section, 20b ... flocculating agent second supply section, 21 ... mud storage tank, 21a ... Third sediment transfer part, 22 ... Dehydration device

Claims (15)

A raw water tank into which raw water containing anions of inorganic compounds other than sulfate ions and sulfate ions is introduced;
A barium tank for holding a barium aqueous solution containing barium ions;
A barium supply section for supplying the barium aqueous solution from the barium tank to the raw water tank;
A first mixed solution of the raw water introduced into the raw water tank and the barium aqueous solution mixed with the raw water is introduced, and the barium sulfate and the first supernatant liquid contained in the first mixed solution are separated. A cloudy water treatment device,
A first liquid mixture feeding section for feeding the first liquid mixture from the raw water tank to the first muddy water treatment device;
An adsorption tank into which the first supernatant is introduced;
A first supernatant liquid feeding section for feeding the first supernatant liquid from the first muddy water treatment device to the adsorption tank;
A chemical tank for holding a chemical solution containing polylactic acid porous particles;
A chemical supply unit for supplying the chemical from the chemical tank to the adsorption tank;
A water treatment system comprising: A second mixed liquid of the first supernatant introduced into the adsorption tank and the chemical mixed with the first supernatant is introduced, and the polylactic acid porous particles and the second supernatant contained in the second mixed liquid are introduced. A second muddy water treatment device for separating the liquid,
A second liquid mixture feeding section for feeding the second liquid mixture from the adsorption tank to the second muddy water treatment device;
The water treatment system according to claim 1, comprising: A third storage tank holding a flocculant for aggregating the barium sulfate and polylactic acid porous particles;
A flocculant first supply section for supplying the flocculant from the third storage tank to the first muddy water treatment device;
A flocculant second supply unit for supplying the flocculant from the third storage tank to the second muddy water treatment device;
The water treatment system according to claim 2, comprising: A discharge tank for receiving and temporarily storing the second supernatant liquid;
A second supernatant liquid feeding section for feeding the second supernatant liquid from the second muddy water treatment device to the discharge tank;
The water treatment system according to claim 2 or 3, characterized by comprising: A mud storage tank for receiving a precipitate containing the polylactic acid porous particles from the second muddy water treatment device;
A second sediment transfer section for transferring the precipitate from the second muddy water treatment device to the mud storage tank;
A first sediment transfer section for transferring the barium sulfate from the first muddy water treatment device to the mud tank;
The water treatment system according to any one of claims 2 to 4, wherein the water treatment system is provided. A dehydrator for dehydrating at least one of the barium sulfate and the precipitate;
A third precipitate transfer section for transferring at least one of the barium sulfate and the precipitate from the mud storage tank to the dehydrator;
The water treatment system according to claim 5, comprising: A water treatment method using the water treatment system according to any one of claims 1 to 6,
Introducing the raw water into the raw water tank;
Supplying the barium aqueous solution from the barium tank to the raw water tank;
The raw water and the barium aqueous solution are mixed in the raw water tank, the first mixed liquid is introduced into the first muddy water treatment device, and barium sulfate and the first supernatant liquid contained in the first mixed liquid are separated. Process,
Introducing the first supernatant into the adsorption tank;
Supplying the chemical solution from the chemical tank to the adsorption tank;
The step of mixing the first supernatant liquid and the chemical liquid in the adsorption tank, and adsorbing the anion of the inorganic compound to the polylactic acid porous particles contained in the chemical liquid in the obtained second mixed liquid When,
A water treatment method characterized by comprising: A first step of obtaining a primary treatment liquid in which the concentration of free sulfate ions is reduced by adding barium ions to raw water containing anions of inorganic compounds other than sulfate ions and sulfate ions to generate barium sulfate;
By bringing the primary treatment liquid into contact with the polylactic acid porous particles, the anions of the inorganic compound are adsorbed on the polylactic acid porous particles to obtain a secondary treatment liquid in which the concentration of the anions of the inorganic compound is reduced. The second step;
A water treatment method characterized by comprising: A raw water tank into which raw water containing anions of inorganic compounds other than sulfate ions and sulfate ions is introduced;
A barium tank for holding a barium aqueous solution containing barium ions;
A barium supply section for supplying the barium aqueous solution from the barium tank to the raw water tank;
An adsorption tank into which a first mixed liquid of the raw water introduced into the raw water tank and the barium aqueous solution mixed therewith is introduced;
A first liquid mixture feeding section for feeding the first liquid mixture from the raw water tank to the adsorption tank;
A chemical tank for holding a chemical solution containing polylactic acid porous particles;
A chemical supply unit for supplying the chemical from the chemical tank to the adsorption tank;
A water treatment system comprising: A second mixed liquid of the first mixed liquid introduced into the adsorption tank and the chemical liquid mixed therewith is introduced, and the barium sulfate and polylactic acid porous particles contained in the second mixed liquid and the second A second muddy water treatment device for separating the supernatant liquid of
A second liquid mixture feeding section for feeding the second liquid mixture from the adsorption tank to the second muddy water treatment device;
The water treatment system according to claim 9, comprising: A third storage tank holding a flocculant for aggregating the barium sulfate and polylactic acid porous particles;
A flocculant second supply unit for supplying the flocculant from the third storage tank to the second muddy water treatment device;
The water treatment system according to claim 10, comprising: A discharge tank for receiving and temporarily storing the second supernatant liquid;
A second supernatant liquid feeding section for feeding the second supernatant liquid from the second muddy water treatment device to the discharge tank;
The water treatment system according to claim 10 or 11, further comprising: A mud storage tank for receiving a precipitate containing the barium sulfate and polylactic acid porous particles from the second muddy water treatment device;
A second sediment transfer section for transferring the precipitate from the second muddy water treatment device to the mud storage tank;
The water treatment system according to any one of claims 10 to 12, wherein the water treatment system is provided. A dehydrator for dehydrating the precipitate;
A third precipitate transfer section for transferring the precipitate from the mud tank to the dehydrator;
The water treatment system according to claim 13, comprising: A water treatment method using the water treatment system according to any one of claims 9 to 14,
Introducing the raw water into the raw water tank;
Supplying the barium aqueous solution from the barium tank to the raw water tank;
Mixing the raw water and the barium aqueous solution in the raw water tank, and introducing the formed first mixed liquid containing barium sulfate into the adsorption tank;
Supplying the chemical solution from the chemical tank to the adsorption tank;
Mixing the first mixed solution and the chemical solution in the adsorption tank, and adsorbing the anion of the inorganic compound to the polylactic acid porous particles contained in the chemical solution in the obtained second mixed solution; The water treatment method characterized by having.

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