JP2015155090A - Water treatment device, water treatment method, production method of useful substance, and floating matter remover for water treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment device, water treatment method, production method of useful substance, and floating matter remover for water treatment device capable of performing water treatment which is suitable for cyclic use of a resource with less environmental load, efficiently and inexpensively.

SOLUTION: A water treatment device comprises: a neutralization treatment tank for performing neutralization treatment of water to be treated by adding a woody biomass combustion ash; and a settling tank into which the water to be treated which has passed through the neutralization treatment tank, is introduced, and in which settling of a neutralization product in the introduced water to be treated is carried out. In the settling tank, floating matter in the water to be treated is treated to be removed with the woody biomass combustion ash in the introduced water to be treated.

COPYRIGHT: (C)2015,JPO&INPIT

Description

  The present invention relates to a water treatment device, a water treatment method, a method for producing a useful substance, and a suspended matter removing agent for a water treatment device. More specifically, the present invention relates to a water treatment device for treating water to be treated, a water treatment method, a method for producing a useful substance, and a floating substance removing agent for a water treatment device.

  In Japan, there are many hot-air volcanic gas fumaroles containing hydrogen sulfide. When this volcanic gas comes into contact with groundwater flowing on the mountainside, a hot spring containing sulfide ions, that is, a sulfur spring, is born. Hot springs are often a valuable tourism resource for the region where they exist.

  On the other hand, rivers and groundwater flowing down in the hot spring area become strongly acidic due to the influence of sulfide ions. Due to the acidification of river water, (1) decrease in the number of species of animals and plants that live in the area, (2) decrease in crop growth and yield when using river water as agricultural water, (3) made of concrete There are concerns about rapid deterioration due to neutralization of river structures.

  As countermeasures against acidification of river water, neutralization projects have been planned and implemented in various places including Gunma Prefecture since the 1960s. In the neutralization business, lime is dissolved in river water to prepare lime milk, and the pH is increased by continuously feeding the lime milk into an acidic river (see Non-Patent Document 1).

  In addition, the neutralization treatment technology has been used in addition to measures for acidification of environmental water such as rivers. For example, in various production / processing plants, a large amount of strongly acidic or strongly alkaline wastewater is generated in the process. The generated strongly acidic or strongly alkaline wastewater is generally treated or rendered harmless biologically or physicochemically after neutralization and discharged into rivers or discharged into sewers.

  Patent Document 1 discloses a wastewater neutralization treatment technique using lime milk.

Japanese Patent Application Laid-Open No. 8-294663

Ministry of Land, Infrastructure, Transport and Tourism, Kanto Regional Development Bureau, Shinki Dam Water Quality Management Center website, http://www.ktr.mlit.go.jp/sinaki.

  However, the neutralization treatment of the environmental water described above requires a large amount of lime, which is a natural mineral resource, and in the course of the neutralization treatment, calcium sulfate, such as gypsum, is proportional to the input amount of lime milk. A neutralized product that is difficult to circulate is generated. In addition, chemicals such as hydrochloric acid, sulfuric acid, and sodium hydroxide are used in large quantities for the above-described neutralization treatment of industrial wastewater.

  The present invention relates to a water treatment apparatus, a water treatment method, a method for producing useful substances, and a floating treatment removal for a water treatment apparatus that can efficiently perform water treatment with low environmental impact and suitable for recycling of resources at low cost. An agent is provided.

In the water treatment apparatus according to the present invention, the water to be treated is neutralized by the woody biomass combustion ash added to the water to be treated, and the water to be treated that has passed through the neutralization tank is introduced. A sedimentation tank for precipitating the neutralized product in the treated water introduced, and the sedimentation tank removes suspended matter in the treated water by the woody biomass combustion ash of the introduced treated water. It is the structure which performs a removal process.
Here, the neutralization treatment in the present specification refers to a treatment for weakening the property as acid or base of the water to be treated, and is not limited to setting the pH of the water to be treated to 7.
The water treatment apparatus further includes an electrolytic cell having a porous electrode, and the electrolytic cell electrolyzes the water to be treated, thereby neutralizing the water to be treated and recovering useful substances in the water to be treated. The structure to perform may be sufficient.
The water treatment method according to the present invention is a method in which woody biomass combustion ash is present in the treated water, the treated water is neutralized, and the suspended matter in the treated water is removed.
The method for producing a useful substance according to the present invention is a method for obtaining a useful substance in the water to be treated by neutralizing the water to be treated in the presence of woody biomass combustion ash in the water to be treated.
The manufacturing method may be a method of obtaining useful substances in the water to be treated by electrolyzing the water to be treated after the neutralization treatment.
The floating substance removing agent for water treatment apparatus according to the present invention is configured to contain woody biomass combustion ash.

  ADVANTAGE OF THE INVENTION According to this invention, the water treatment which has little environmental load and was adapted for the recycling use of resources can be performed efficiently at low cost.

It is a schematic diagram which shows the structural example of the water treatment apparatus of the 1st Embodiment of this invention. It is a schematic diagram which shows the structural example of the water treatment apparatus of the 2nd Embodiment of this invention. It is a 1st graph which shows the result of a 1st experiment example. It is a 2nd graph which shows the result of a 1st experiment example. It is a schematic diagram which shows the electrolytic cell used for the 3rd experiment example. It is a 1st graph which shows the result of a 3rd experiment example. It is a 2nd graph which shows the result of a 3rd experiment example.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described with reference to the drawings. A plurality of embodiments described below show examples of typical embodiments of the present invention, and the scope of the present invention is not interpreted narrowly.

<1. Embodiment of suspended matter removing agent for water treatment device>
The suspended matter removal agent for water treatment apparatus of this embodiment consists of woody biomass fuel ash. The suspended matter removing agent for water treatment apparatus of the present embodiment may be combustion ash generated from a biomass power plant using wood chips as fuel. In this case, the raw material of the wood chip may be, for example, at least one of construction waste, thinned wood, and raw wood, but is not limited thereto. The raw material of the wood chip may include food residues such as tea grounds and coffee grounds.

  As described later, when woody biomass combustion ash was applied to a water treatment device, the effect of removing suspended matters from the water to be treated was unexpectedly obtained.

<2. Water Treatment Device of First Embodiment>
[Device configuration example]
FIG. 1 is a schematic diagram illustrating a configuration example of a water treatment device 10 of the present embodiment. As shown in FIG. 1, the water treatment device 10 includes a neutralization treatment tank 11 and a precipitation tank 12. The neutralization treatment tank 11 is disposed upstream of the settling tank 12 in the flow direction of the water to be treated. The neutralization treatment tank 11 and the precipitation tank 12 are in fluid communication with each other through a flow path such as a pipe.

[Neutralization treatment tank 11]
The neutralization treatment tank 11 is configured to neutralize the treated water introduced into the neutralized treatment tank 11 with the woody biomass combustion ash added to the treated water. The specific aspect of to-be-processed water is not limited. For example, the water to be treated may be acidic river water or factory waste water.

  The neutralization treatment tank 11 may have a configuration in which the water to be treated introduced from the water system and the woody biomass combustion ash introduced into the neutralization treatment tank 11 are mixed and neutralized. Although the specific aspect of the neutralization processing tank 11 in this case is not limited, you may employ | adopt a tubular reaction tank as an example of a preferable aspect. By adopting the tubular reaction tank, the water to be treated and the woody biomass combustion ash can be efficiently stirred and mixed using the energy of the water to be treated, that is, the kinetic energy and the potential energy. Moreover, according to this aspect, it is not necessary to separately provide power for mechanical stirring, so that the cost can be suppressed.

  The woody biomass combustion ash added to the water to be treated may be stocked in a combustion ash storage device such as a silo (not shown). Further, the method for introducing the woody biomass combustion ash into the neutralization tank 11 is not limited. For example, the woody biomass combustion ash may be fed into the neutralization treatment tank 11 by a known feeding device such as a melting device that feeds the woody biomass combustion ash as ash milk.

[Settling tank 12]
The sedimentation tank 12 has a configuration in which treated water that has passed through the neutralizing treatment tank 11, that is, treated water after neutralization treatment, is introduced. Moreover, the settling tank 12 is a structure which solid-liquid-separates and precipitates the neutralization product in the to-be-processed water introduce | transduced in the settling tank 12. FIG. The neutralized product contains nutrients, ie useful substances such as phosphorus and potassium. Furthermore, the settling tank 12 is a structure which performs the removal process of the suspended | floating matter in this to-be-processed water by the introduced wood type biomass combustion ash of to-be-processed water. In addition, this invention does not exclude that the neutralization process of the to-be-processed water by wood type biomass combustion ash advances in the sedimentation tank 12. FIG.

  In the sedimentation tank 12, the neutralized product in the water to be treated is recovered by precipitation and discharge to the outside of the sedimentation tank 12 through the flow path. The recovered neutralized product can be applied as a soil modifier in a forest or the like, for example, in the form of a concentrate.

[Device operation example]
Next, an operation example of the water treatment device 10 of the present embodiment will be described. This operation example is an embodiment of a water treatment method and a useful substance production method according to the present invention.

[Neutralization process]
In the water treatment method of this embodiment, first, in the neutralization tank 11, the water to be treated is neutralized by adding woody biomass combustion ash to the water to be treated. The neutralization treatment may be achieved by elution of an alkaline component contained in the woody biomass combustion ash. At this time, the addition amount of the woody biomass combustion ash is not limited, but as an example of a preferred embodiment, the addition amount of the woody biomass combustion ash to the water to be treated having a pH of 2 to 3 may be 3 to 5 g / L. Moreover, it is good also considering the addition amount of the woody biomass combustion ash with respect to the to-be-processed water of pH 3-4 as 1.0-1.5 g / L. By doing so, the neutralization process of to-be-processed water can be performed rapidly and appropriately.

  Further, the time required for the neutralization treatment, that is, the residence time of the water to be treated in the neutralization treatment tank 11 is not limited, but as an example of a preferred embodiment, several minutes or more may be adopted. By doing so, the pH of the water to be treated can be sufficiently raised.

[Precipitation and suspended matter removal process]
Next, the water to be treated after the neutralization treatment by the neutralization treatment tank 11 is introduced into the precipitation tank 12. At this time, the water to be treated may be introduced into the sedimentation tank 12 using the energy of the flow in the neutralization treatment tank 11. Alternatively, the water to be treated may be introduced into the sedimentation tank 12 using a liquid delivery device such as a pump.

  The water to be treated introduced into the settling tank 12 is separated from the neutralized product. In addition, when suspended matter exists in the treated water, the treated water is separated from the suspended matter by the woody biomass combustion ash. That is, the removal process of the suspended | floating matter in to-be-processed water is performed. The suspended matter may be separated from the water to be treated while attached to the woody biomass combustion ash. The suspended matter may be adsorbed and aggregated by the woody biomass combustion ash. The suspended matter may be precipitated in the settling tank 12.

  Although the residence time of the water to be treated in the sedimentation tank 12 is not limited, 0.5 hour or more may be adopted as an example of a preferred embodiment. By doing so, suspended matters can be sufficiently removed.

  The treated water that has passed through the settling tank 12 is discharged as treated water that has been subjected to water treatment by the water treatment device 10 of the present embodiment, that is, neutralization, solid-liquid separation, and suspended matter removal treatment.

  According to the water treatment apparatus 10 of the present embodiment, water treatment with less environmental load can be realized by using woody biomass combustion ash with less harmful substances. Moreover, since the neutralized product by the woody biomass combustion ash can be used as a soil conditioner and the like due to the inclusion of nutrient salts and the like, it is possible to realize the recycling of resources. Furthermore, since the usage-amount of lime which is a mineral resource can be suppressed, it can contribute to environmental conservation. Furthermore, water treatment using woody biomass combustion ash can be realized at a lower cost than water treatment using a large amount of chemicals such as hydrochloric acid, sulfuric acid and sodium hydroxide. In addition, the woody biomass combustion ash can be used not only for neutralization treatment but also for removal of suspended matters from the water to be treated, so that efficient water treatment can be realized.

<3. Water Treatment Device of Second Embodiment>
[Device configuration example]
FIG. 2 is a schematic diagram illustrating a configuration example of the water treatment device 10 of the present embodiment. As shown in FIG. 2, the water treatment device 10 of the present embodiment further includes an electrolytic cell 130 in addition to the configuration of the water treatment device 10 of FIG. 1. The electrolytic bath 130 is disposed downstream of the sedimentation bath 12 in the flow direction of the water to be treated. The electrolytic bath 130 and the sedimentation bath 12 are in fluid communication with a flow path such as a pipe. The configuration in which the electrolytic bath 130 is connected upstream of the neutralization treatment tank 11 and the water to be treated that has passed through the electrolytic bath 130 is introduced into the neutralization treatment tank 11 is also within the scope of the present invention.

[Electrolysis tank 130]
The electrolytic cell 130 has a porous electrode 131. The electrolytic bath 130 is configured to neutralize the water to be treated by electrolyzing the water to be treated introduced from the sedimentation tank 12. The electrolytic bath 130 is configured to collect useful substances in the water to be treated by electrolyzing the water to be treated introduced from the settling tank 12. The electrolytic bath 130 may control the pH of the water to be treated after the neutralization treatment by the neutralization treatment bath 11. When the water to be treated is alkaline, the water to be treated may be directly introduced into the electrolytic cell 130 as indicated by a one-dot chain arrow in FIG. In this case, the electrolytic cell 130 is configured to neutralize the directly introduced water to be treated and collect useful substances in the water to be treated. Incidentally, when the water to be treated is alkaline and it is necessary to remove the suspended matter, the water to be treated may be directly introduced into the settling tank 12 as shown by the broken line arrow in FIG.

The aspect of the neutralization process of the to-be-processed water in the electrolytic vessel 130 is not limited. For example, an anion in the acidic water to be treated migrates and concentrates in the porous electrode 131 (anode), so that the electrical neutrality is lost, and OH ⁻ is generated by electrolysis to carry out a neutralization treatment. It may be broken. Alternatively, cations in the alkaline water to be treated migrate and concentrate in the porous electrode 131 (cathode), so that the electric neutrality is lost, and H ⁺ is generated by electrolysis to carry out the neutralization treatment. It may be broken.

  The aspect of the collection of useful substances in the electrolytic cell 130 is not limited. For example, the electrolytic bath 130 may crystallize valuable substances (for example, nitrogen, phosphorus, potassium, copper, and zinc) in the water to be treated or generate hydrogen by electrolyzing the water to be treated. . The recovered crystalline substance can be used, for example, as a fertilizer raw material or industrial use. The recovered hydrogen can be stocked, for example, in a storage cylinder or the like and used as fuel for the fuel cell when necessary.

  Although the residence time of the water to be treated in the electrolytic bath 130 is not limited, 0.5 hour or more may be adopted as an example of a preferred embodiment. By doing so, the pH of water to be treated can be sufficiently adjusted, and useful substances can be sufficiently recovered.

[Device operation example]
Next, an operation example of the water treatment apparatus 10 of the present embodiment will be described focusing on differences from the first embodiment. This operation example is an embodiment of a water treatment method and a useful substance production method according to the present invention.
[Electrolytic neutralization and useful substance recovery process]
In this step, treated water that has been subjected to the water treatment in the first embodiment (referred to as treated water in this embodiment) is introduced into the electrolytic cell 130. However, alkaline treatment water that does not require removal of suspended solids is directly introduced into the electrolytic bath 130, or alkaline treated water directly introduced into the precipitation vessel 12 is removed from the suspended solids in the precipitation vessel 12. Or may be introduced via

  Then, the porous electrode 131 is energized by a power source (not shown). At this time, when the water to be treated is acidic, for example, by controlling the polarity of the power source, the porous electrode 131 is used as an anode, the counter electrode (not shown) facing the cathode is used as a cathode, and the water to be treated is alkaline. The porous electrode 131 may be a cathode and the counter electrode may be an anode.

  When the porous electrode 131 is energized, the water to be treated in the electrolytic bath 130 is electrolyzed, and the water to be treated is neutralized. At this time, valuable substances in the water to be treated are crystallized, and hydrogen is generated. These useful substances are discharged from the electrolytic cell 130 to the outside through a flow path such as a pipe line. In this way, the useful substance is recovered by electrolyzing the water to be treated in the electrolytic bath 130.

The working current and time of electrolysis are not limited, but as an example of a preferred embodiment, for example, for water to be treated having a pH of ² to 4, a current density of 0.35 mA / cm ² , a residence time of 1 hour, and a pH of 11 to 13 The current density may be 0.45 mA / cm ² and the residence time may be 1 hour with respect to the water to be treated. By doing so, the pH of the water to be treated can be sufficiently adjusted in a relatively short time.

  According to the water treatment device 10 of the present embodiment, more effective resource recycling can be realized by collecting useful substances. Moreover, pH control of the to-be-processed water after the neutralization process by the neutralization processing tank 11 can be performed.

Experimental example

[First Experimental Example]
[experimental method]
In this experimental example, neutralization experiment of acidic river water was conducted using woody biomass combustion ash (hereinafter abbreviated as combustion ash) generated from a biomass power plant. Acidic river water (test water) was sampled from Yukawa and Tanizawa River (two places, upstream and downstream) in Kusatsu Town. Here, the possibility of neutralization of actual acidic river water with combustion ash, the amount of combustion ash necessary for neutralization of acidic river water, and the change in pH after addition of combustion ash were examined.

  Specifically, fine powder combustion ash is added to 1 liter of sampled water sampled in a container assumed to be a neutralization treatment tank 11, gently stirred using a magnetic stirrer, and the hydrogen ion concentration after 5 minutes The index (pH) was measured. The same neutralization experiment was conducted using distilled water and tap water as control test water.

  Moreover, in order to confirm the pH change after combustion ash addition, 1 to 5 g of combustion ash was added to 1 L of test water (acid river water), and pH change was observed until 24 hours later.

[Experimental result]
FIG. 3 shows the change in pH depending on the amount of combustion ash added. The pH of acidic river water (Yukawa as an example) gradually increased from 2.2 by adding combustion ash, and became 7 or more when 15 g of combustion ash was added. On the other hand, in the experiment using distilled water and tap water, the pH became 10 or more when 2 g of combustion ash was added. It was found that the pH rises more easily than when acid river water is used. In experiments conducted using actual river water, the pH change was relatively gradual, but it was found that neutralization with combustion ash is possible.

  FIG. 4 shows the change over time in pH after the addition of combustion ash. As shown in FIG. 4, in an experiment in which the concentration of combustion ash was 3 to 5 g / L, it was confirmed that the pH increased by about 1 in 24 hours, and neutralization was achieved in a relatively short time. Moreover, it turned out that the alkaline component which elutes from combustion ash exists gradually. It can be judged that the Yukawa river water can be neutralized with a combustion ash addition amount of 3 to 8 g / L.

  Next, the result of the neutralization experiment using the river water of the Tanizawa River will be described. The acidity of Tanizawa River (pH: 3-4) is lower than that of Yukawa, and neutralization treatment (pH: 6 or more) is realized by adding about 1.0-1.5 g of combustion ash to 1 liter of river water. We were able to. As a result of detailed water quality analysis, excessive elution of harmful substances such as chromium was not observed.

[Second Experimental Example]
[experimental method]
Experiments were conducted using acidic river water containing SS (suspended solid) components sampled from the Tanizawa River. Changes in SS concentration were observed when 2 grams of combustion ash was added to 1 liter of acidic river water. Stirring was performed with a magnetic stirrer, and the stirring time was 5 minutes. Then, stirring was stopped and a 1 hour precipitation time was provided.

[Experimental result]
The SS concentration of river water sampled from the downstream of the Tanizawa River was about 40 mg / L before the addition of combustion ash, but decreased to about 5 mg / L after the combustion ash was added and stirred. That is, the removal effect of SS component was confirmed by adding combustion ash.

[Third experimental example]
[experimental method]
In this experimental example, a neutralization experiment was performed using the electrolytic cell 20 shown in FIG. As shown in FIG. 5, the electrolysis cell 20 includes a cylindrical acrylic reactor 21, a cylindrical porous electrode 22 and a titanium base material platinum plating rod 23 mounted inside the acrylic reactor 21. Has been. The cylindrical porous electrode 22 is produced and molded using 0.5 mm granular activated carbon, and has an outer diameter of 6.5 cm, an inner diameter of 4.5 cm, and a length of 25 cm. The titanium base material platinum plating rod 23 has a diameter of about 5 mm.

  The titanium base material platinum plating rod 23 was placed at the center of the cylindrical porous electrode 22 so that the electrolysis was performed uniformly. The test water flowed upward between the electrodes 22 and 23 by plug flow, and the speed (the residence time in the cell) was controlled by the amount of inflow water.

  Connect the lead wire 4 from the direct current stabilizing power source 3 to the electrodes 22 and 23 and control the supply amount (flow rate) of the test water with the liquid feed pump 5 so that the residence time is 1 hour, and the pH of the outflow is stable. I started energizing.

[Experimental result]
a) Neutralization of acidic river water The pH change of the effluent when the Tanizawa river water (sampled from the upstream part) is used as test water, the cylindrical porous electrode 22 is used as an anode, and energization is performed at 75 mA. It is shown in the graph of 6 Δ plot. As shown in FIG. 6, the pH of the effluent water under non-energized conditions was about 3, but gradually increased with the start of energization, and increased to near neutral after 40 minutes. Thereafter, the pH slightly changed, but it was found that neutralization treatment of acidic river water by the electrolytic method was possible.

  On the other hand, changes in pH when a non-porous cylindrical stainless steel electrode is used as an anode and energization is performed at 100 mA are shown in the graph of the □ plot in FIG. As shown in FIG. 6, in the case of the cylindrical stainless steel electrode, the initial pH was almost the same as that of the cylindrical porous electrode 22, but there was no significant change thereafter, and it remained at about 4.5 at the maximum. . It was found that neutralization treatment was not possible even when the current was increased under the conditions where no porous material was used for the anode.

In addition, the production amount of hydrogen (H ₂ ) was very high, 80 to 90% of the theoretical hydrogen generation amount that can be calculated from the energization amount based on the Faraday law.

b) Neutralization of alkaline water pH change of the effluent water when the alkaline water prepared using sodium hydroxide was used as the test water, the cylindrical porous electrode 22 was used as the cathode, and energization was performed at 100 mA. This is shown in the □ plot graph. As shown in FIG. 7, the pH of the water to be treated began to gradually decrease 40 minutes after the start of energization, and became near neutral after 1 hour. It has been found that the use of a porous material for the cathode makes it possible to neutralize alkaline water by electrolysis.

  The operations and effects described in the above embodiment are merely examples, are not limited, and may have other operations and effects.

Of the above-described neutralization treatment tank, precipitation tank, and electrolytic tank, at least two of them may be integrated as one tank.
The following configuration can also be adopted.
It has a porous electrode and has an electrolytic cell into which water to be treated is introduced,
The said electrolytic vessel is a water treatment apparatus which performs the neutralization process of the said to-be-treated water, and collection | recovery of the useful substance in the to-be-treated water by electrolyzing the to-be-treated water.

10 Water Treatment Equipment 11 Neutralization Treatment Tank 12 Precipitation Tank

Claims (6)

A neutralization treatment tank for neutralizing the treated water with the woody biomass combustion ash added to the treated water;
The treated water that has passed through the neutralization treatment tank is introduced, and a precipitation tank that precipitates a neutralized product in the introduced treated water, and
The said sedimentation tank is a water treatment apparatus which removes the suspended | floating matter in the said to-be-processed water with the said woody biomass combustion ash of the to-be-processed water introduced. Further comprising an electrolytic cell having a porous electrode;
The water treatment apparatus according to claim 1, wherein the electrolytic bath performs neutralization treatment of the water to be treated and recovery of useful substances in the water to be treated by electrolyzing the water to be treated.   A water treatment method in which woody biomass combustion ash is present in the water to be treated, the water to be treated is neutralized, and suspended matter in the water to be treated is removed.   The manufacturing method of the useful substance which obtains the useful substance in the said to-be-processed water by making woody biomass combustion ash exist in to-be-processed water, and neutralizing the said to-be-processed water.   The method for producing a useful substance according to claim 4, wherein a useful substance in the treated water is obtained by electrolyzing the treated water after the neutralization treatment. A suspended matter remover for water treatment equipment containing woody biomass combustion ash.

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