JP2005103518A - Heavy metal wastewater treatment system and heavy metal wastewater treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heavy metal treatment system capable of efficiently removing a heavy metal ion component contained in heavy metal wastewater containing heavy metal ions, reducing environmental load caused by post treatment of concentrated water and adsorbent, and having excellent recycling efficiency, and to provide a heavy metal treatment method. <P>SOLUTION: The heavy metal treatment system 1 is provided with a heavy metal adsorption device 2 housing a ferrous adsorbent for adsorbing the heavy metal ions and adsorbing the ion component in the heavy metal wastewater to the ferrous adsorbent, a CDT 3 removing the heavy metal ion component remaining in the heavy metal wastewater from which the heavy metal ion component is adsorbed by the heavy metal adsorption device 2, and discharging cleaned water from which the heavy metal ion component is removed and discharging the concentrated water in which the heavy metal ion component is concentrated, and a circulation means (controller 4, second communication pipe 6b, second opening and closing valve 7b, and concentrated water discharge passage 8) returning the concentrated water from the CDT 3 to the heavy metal adsorption device 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heavy metal wastewater treatment apparatus and a heavy metal wastewater treatment method for removing heavy metals contained in heavy metal wastewater containing heavy metals such as arsenic, lead, cadmium, chromium, selenium, and mercury.

  In recent years, soil pollution and waste pollution due to heavy metal drainage containing heavy metals such as arsenic, lead, cadmium, chromium, selenium, mercury have been found in various places mainly in industrial waste final disposal sites and factories, For this reason, research for removing heavy metal ion components contained in heavy metal wastewater has been advanced.

  Many of these heavy metal wastewaters are harmful, and the influence of pollution on the entire environment, such as air, water quality, and soil, is significant. For this reason, pollution control values such as the Air Pollution Control Law, Odor Control Law and Water Pollution Control Law have been established for the treatment of waste gas generated by incineration of general waste and industrial waste. Is required.

  The heavy metal waste water is known to contain salts, DXNs, other organic halogen compounds, various endocrine disrupting substances, and other persistent compounds. Among organic halogen compounds, the problem of dioxins (hereinafter also referred to as DXNs) has recently attracted attention.

Then, what is shown, for example in the following patent document 1 is proposed as a waste water treatment apparatus which processes waste water containing salts and a hardly decomposable compound efficiently. This apparatus comprises a pretreatment means for pretreating wastewater containing salts and a hardly decomposable compound, and reverse osmosis for separating the wastewater pretreated by the pretreatment means into a permeate and a concentrate by reverse osmosis membrane treatment. Apparatus, adsorptive oxidative decomposition apparatus that performs oxidative decomposition treatment of the hard-to-decompose compounds in the concentrate concentrated by the reverse osmosis apparatus with active chemical species, and desalination treatment that performs desalination after the treatment by the adsorptive oxidative decomposition apparatus It has a device.
JP 2003-10867 A

  However, in the above, the concentrated solution from the reverse osmosis membrane device that separates the permeate and the concentrated solution is further processed, and a part thereof is returned to the inlet side of the reverse osmosis membrane device. Since concentrated water is discharged, post-treatment of the concentrated water is inevitable. In addition, it is necessary to treat an adsorbent (for example, a catalyst-supporting porous body) that adsorbs a heavy metal ion component in each treatment apparatus. Therefore, the actual situation is that the post-treatment of the concentrated water and the adsorbent requires equipment costs and running costs, and the environmental burden due to these post-treatments cannot be avoided.

  The present invention has been made in view of the circumstances as described above, and can efficiently remove heavy metal ion components contained in heavy metal wastewater containing heavy metal ions, and also by post-treatment of concentrated water and adsorbents. The purpose is to provide a heavy metal wastewater treatment device and a heavy metal wastewater treatment method that eliminates environmental burdens and has excellent recyclability.

  In order to achieve the above object, the heavy metal wastewater treatment apparatus of the present invention is a heavy metal wastewater treatment apparatus that removes heavy metal ion components contained in heavy metal wastewater containing heavy metal ions, and is an iron-based material that adsorbs the heavy metal ion components. A heavy metal adsorption device that contains an adsorbent and adsorbs the ionic components in the heavy metal wastewater to the iron-based adsorbent, and a heavy metal ion component that remains in the heavy metal wastewater in which the heavy metal ion components are adsorbed by the heavy metal adsorption device. A deionizer that removes the purified water from which the heavy metal ion component has been removed and the concentrated water from which the removed heavy metal ion component has been concentrated, and the concentrated metal discharged from the deionizer to the heavy metal adsorption device The gist of the present invention is that it is provided with a circulation means for returning to the above.

  In order to achieve the above object, the heavy metal wastewater treatment method of the present invention is a heavy metal wastewater treatment method for removing heavy metal ion components contained in heavy metal wastewater containing heavy metal ions, and adsorbs the heavy metal ion components. The heavy metal adsorber containing the iron-based adsorbent adsorbs the ion component in the heavy metal wastewater to the iron-based adsorbent, and the heavy metal ion remaining in the heavy metal wastewater in which the heavy metal ion component is adsorbed in the heavy metal adsorber The component is further removed by a deionizer, and the purified water from which the heavy metal ion component is removed and the concentrated water from which the removed heavy metal ion component is concentrated are discharged, and the concentrated water discharged from the deionizer is discharged from the deionizer. The gist is to return to the heavy metal adsorption device.

  That is, according to the heavy metal wastewater treatment apparatus and method of the present invention, the deionization apparatus further removes the heavy metal ion component remaining in the heavy metal wastewater on which the heavy metal ion component is adsorbed by the heavy metal adsorption device, and the heavy metal ion component And the concentrated water in which the removed heavy metal ion component is concentrated is discharged. Then, the concentrated water discharged from the deionizer is returned to the heavy metal adsorber and the concentrated heavy metal ion component is adsorbed by the iron-based adsorbent, and deionization is performed.

  Thus, in the apparatus and method of the present invention, when treating heavy metal wastewater containing heavy metal ions, concentrated water enriched with heavy metal ions is not discharged at all. And the post-treatment process of the concentrated water is completely unnecessary, and the equipment for the post-treatment of the concentrated water, the maintenance of the equipment, the work accompanying them, etc. can be omitted completely. Therefore, the treatment cost of heavy metal wastewater can be greatly reduced, and the environmental burden due to the post-treatment of the concentrated water can be greatly reduced.

  Moreover, the heavy metal ion component contained in the heavy metal wastewater is adsorbed by the iron-based adsorbent of the heavy metal adsorption device while the heavy metal wastewater circulates through the heavy metal adsorption device and the deionization device. For this reason, the adsorption | suction waste material by which the heavy metal ion was adsorb | sucked can be utilized as an iron scrap raw material required in the case of steelmaking, can be melt | dissolved and it can reproduce | regenerate as an iron-type material. Thus, the post-treatment process of the adsorption waste material is completely unnecessary, and the equipment for post-treatment of the adsorbent material, the maintenance of the equipment, and the work accompanying them can be omitted completely. In addition, it is possible to use a relatively inexpensive adsorbent, such as an iron-based adsorbent, as a consumable, and to recycle the consumable. Therefore, the processing cost of heavy metal wastewater can be greatly reduced, the environmental load due to post-treatment of the adsorbed waste material can be greatly reduced, and the recyclability is excellent.

  Thus, since the apparatus and method of the present invention completely eliminates the discharge of concentrated water and adsorbs heavy metal ion components to the iron-based adsorbent, the processing cost of heavy metal wastewater can be greatly reduced, It can greatly reduce the environmental burden due to post-treatment of concentrated water and adsorbed waste, and is excellent in recyclability.

  In the present invention, the deionization device applies a DC voltage between the electrodes present in the heavy metal wastewater to adsorb the heavy metal ion component remaining in the heavy metal wastewater to the both electrodes, thereby purifying the heavy metal wastewater. As a result, the DC voltage applied during deionization between the two electrodes is released, the anode side and the cathode side are short-circuited, or reversely connected, so that they are adsorbed on both electrodes. When the heavy metal ion component is discharged into the heavy metal waste water and the heavy metal waste water is discharged as concentrated water, the heavy metal ion component remaining in the heavy metal waste water is removed by the deionization treatment. The heavy metal drainage can be discharged as purified water by being adsorbed on the electrode, and the heavy metal ion component adsorbed on both the electrodes by the regeneration treatment is put into the heavy metal drainage. It is possible to discharge the heavy metals wastewater as concentrated water out.

  For example, if the heavy metal ion component adhering to both electrodes is saturated and the ability to adsorb the heavy metal ion component (adsorption capacity) is reduced by performing the deionization process in the deionizer, both regeneration processes are performed. Since the ionic component adhering to the electrode is released, the adsorption ability can be recovered. In this way, the deionization process in the deionizer saturates the heavy metal ion components adhering to both electrodes, and it is necessary to prevent a reduction in adsorption capacity. Since water is returned to the heavy metal adsorption device without being discharged to the outside of the device, the environmental load can be reduced. Moreover, in the deionization apparatus, heavy metal ions adsorbed by the deionization process are completely released by the regeneration process and discharged as concentrated water. The discharged concentrated water is adsorbed and removed by the iron-based adsorbent in the heavy metal adsorption device. Therefore, in such a heavy metal wastewater treatment device, the adsorption waste material containing the removed heavy metal ions is only the iron-based adsorbent used in the heavy metal adsorption device, and no other adsorption waste material or the like is generated. Then, the adsorbed waste material on which the heavy metal ions are adsorbed can be dissolved and regenerated as an iron-based adsorbent without the concentrated water being discharged, and complete recycling can be achieved.

  In addition, such a deionization device removes heavy metal ion components remaining in the concentrated water without lowering the adsorptive capacity even if the concentrated water shows a high pH value due to adsorption by the iron-based adsorbent. can do. Therefore, it is more suitable for the combination with the iron-based adsorbent, and it becomes an apparatus and a method that sufficiently exhibit the above-mentioned complete recycling.

  In the present invention, the deionizer performs a reverse osmosis membrane treatment in which the heavy metal wastewater adsorbed with the heavy metal ion component in the heavy metal adsorption device is filtered through a reverse osmosis membrane to separate the purified water and the concentrated water. In some cases, the reverse osmosis membrane treatment can be constantly separated into purified water and concentrated water. And since this concentrated water is returned to a heavy metal adsorption | suction apparatus, it can prevent being discharged | emitted outside this apparatus similarly to the above-mentioned.

  Next, the best mode for carrying out the present invention will be described.

  FIG. 1 is a diagram showing an embodiment of a heavy metal wastewater treatment apparatus of the present invention.

  As shown in FIG. 1, the heavy metal wastewater treatment apparatus of the present invention is a heavy metal wastewater treatment apparatus 1 that removes heavy metal ion components contained in heavy metal wastewater containing heavy metal ions and discharges it as treated water.

  The heavy metal wastewater treatment apparatus 1 includes a heavy metal adsorption apparatus 2, an electrostatic deionization apparatus (CDT) 3 that is a deionization apparatus, and a control apparatus 4 that controls the CDT 3 and first and second on-off valves 7a and 7b described later. And have.

  The heavy metal adsorption device 2 contains an iron-based adsorbent that adsorbs heavy metal ion components. In the heavy metal adsorbing device 2, heavy metal wastewater is brought into contact with the iron-based adsorbent accommodated therein, and heavy metal ion components in the heavy metal wastewater are adsorbed on the iron-based adsorbent. Adsorption of heavy metal ion components by iron-based adsorbents is based on reactions with iron-based adsorbents (basically, ferritization reactions, oxidation / reduction reactions with metallic iron, and insolubilization reactions with calcium proceed in parallel). Realized.

  In this embodiment, the iron-based adsorbent employs finely divided metallic iron powder containing metallic iron, iron oxide, and a calcium compound. If the heavy metal wastewater contains a high concentration of heavy metals, etc., or if there is a large amount of wastewater containing heavy metals, etc., iron sulfate, iron chloride, iron nitrate, etc. The heavy metal ion component can be effectively removed by adopting a method of adding a soluble iron salt. Furthermore, alkali and / or alkaline earth hydroxides such as sodium hydroxide and potassium hydroxide may be added and heated to 60 ° C. or higher. Since iron ions and hydroxide ions are sufficiently supplied, heavy metal ions such as heavy metals of high concentration react with them to generate ferrite, and are prevented from being discharged in the state of ions such as heavy metals. it can.

  This iron-based adsorbent contains iron oxide in addition to metallic iron and calcium compounds, so that iron oxide is included, and the iron-based adsorbent can be fixed (capability of fixing lead and hexavalent chromium as ferrite). ) Will improve. As iron oxide to be contained, magnetite is desirable. By mixing magnetite with an iron-based adsorbent, the reaction of generating ferrite from heavy metal ions and iron ions can be advanced at room temperature.

  Moreover, the iron-based adsorbent allows the oxidation reaction of the base metal iron with hydroxide ions to proceed more than the dissolution reaction of the metal iron when the calcium compound coexists. As a result, a reduction reaction that is less basic than the dissolution reaction of metallic iron can be performed, and the types of harmful elements that can be reduced and rendered harmless increase.

  The mixing ratio of metallic iron and calcium compound is preferably 1 or more in terms of the molar ratio of metallic iron / calcium compound. By doing so, the solubility of calcium is reduced, and in this reaction, the presence of metallic iron and a calcium compound in the system causes the reaction of calcium to act catalytically. There is no need to mix more calcium compounds.

  On the other hand, the mixing ratio of iron oxide is desirably less than 10% by mass with respect to the total amount of the iron-based adsorbent. When the content of iron oxide is 10% by mass or more, it is possible to prevent the heavy metal or the like from being adsorbed on the iron-based compound surface but difficult to be fixed to the iron-based adsorbent as ferrite. it can.

  This iron-based adsorbent is generally mixed with metallic iron, iron oxide, and the above calcium compound so as to satisfy the above-mentioned predetermined conditions and the conditions described below (total mass of iron is 60 mass% or more). Obtained by. The particle size in that case is not particularly limited, but it is preferably about 0.01 to 10 mm so that handling is easy and iron ions and hydroxide ions are supplied little by little.

  It is also possible to use reduced iron formed by melting and reducing iron-based dust generated at an ironworks or the like together with the calcium compound. This reduced iron is molded in a state in which metallic iron, iron oxide, and calcium inclusions are mixed, and has an appropriate particle size, and thus is particularly suitable as an iron-based adsorbent used in the present invention. .

  In the iron-based adsorbent, the total mass of iron (that is, the total amount of metallic iron and iron oxide converted to the amount of iron) is 60% by mass or more, for example, a relatively large amount of iron oxide. If the total mass of iron is less than 60% by mass, the supply of iron ions necessary for the ferritization reaction cannot be ensured, and it is difficult to immobilize heavy metals as ferrite. can do. In addition, when the iron-based adsorbent (that is, iron-based compound) after recovering the immobilized metal is reused as the iron source for blast furnaces such as steelworks, the iron content is low and there are restrictions on the reuse. Can also be prevented.

  The heavy metal adsorbing device 2 is configured such that an iron-based adsorbent on which a heavy metal ion component is fixed is removably accommodated by contacting with the heavy metal drainage. Thereby, it is possible to take out the iron-based adsorbent in which the heavy metal ion component is immobilized from the heavy metal adsorbing device 2, and it can be easily reused in an ironworks or the like, and valuable resources are effectively used.

  In the CDT3, by applying a DC voltage between the electrodes existing in the heavy metal waste water, the deionization treatment is performed in which the heavy metal ion components remaining in the heavy metal waste water are adsorbed on both electrodes and the heavy metal waste water is discharged as purified water. And removing the DC voltage applied during the deionization process between the two electrodes, short-circuiting the anode side and the cathode side, or reversely connecting them to thereby remove the heavy metal ion component adsorbed on the two electrodes. Regeneration processing is performed in which the heavy metal wastewater is discharged into the heavy metal wastewater and discharged as concentrated water.

  The heavy metal adsorbing device 2 has an inlet connected to the introduction pipe 5, and heavy metal drainage is introduced through the introduction pipe 5. Then, the ionic components in the heavy metal drainage introduced from the introduction pipe 5 are adsorbed by the iron-based adsorbent filled inside, and sent to the CDT 3 from the first communication pipe 6a connected to the discharge port of the heavy metal adsorption device 2. The heavy metal waste water in which the heavy metal ion component is adsorbed by the heavy metal adsorption device is introduced into the CDT 3.

  The drain of the CDT 3 is connected to the first communication pipe 6a, and heavy metal drainage in which heavy metal ion components are adsorbed by the heavy metal adsorption device 2 is introduced through the first communication pipe 6a. And the deionized process produces | generates the treated water from which the heavy metal ion component was removed. This treated water is intended to include purified water and pure water containing a very small amount of heavy metal ions.

  Further, the CDT 3 releases the heavy metal ion component adsorbed on both electrodes by the regeneration treatment into the heavy metal drainage (through the liquid). In this way, the heavy metal ion component released in the regeneration process is collected in a liquid flow and discharged as concentrated water containing a large amount of the heavy metal ion component.

  The treated water outlet of the CDT 3 is connected to a second communication pipe 6b that discharges treated water and concentrated water from the CDT 3. The second communication pipe 6b is branched into a treated water discharge passage 10 for discharging treated water after deionization treatment and a concentrated water discharge passage 8 for discharging concentrated water containing heavy metal ions released in the regeneration treatment. . The treated water discharge passage 10 is provided with a first on-off valve 7a for controlling the opening and closing of the treated water discharge after the deionization treatment, and the concentrated water discharge passage 8 contains the heavy metal ion content released by the regeneration process. A second on-off valve 7b that controls the opening and closing of the concentrated water discharge is provided.

  That is, the deionizer 3 discharges the first on-off valve 7a for opening and closing the treated water discharge passage 10 for discharging the treated water after the deionization process, and the concentrated water containing the heavy metal ion component released by the regeneration process. And a second on-off valve 7b for opening and closing the concentrated water discharge path 8.

  Thus, by providing the first on-off valve 7a and the second on-off valve 7b in the deionizer 3, the discharge directions of the concentrated water and the treated water can be separated.

  The downstream end of the concentrated water discharge path 8 is connected to the introduction pipe 5 so that the concentrated water passing therethrough merges with the heavy metal drainage passing through the introduction pipe 5. Thereby, the concentrated water by the regeneration process is returned to the deionization apparatus 3, and the heavy metal ion component is again adsorbed by the heavy metal adsorption apparatus 2, whereby the treated water by the deionization process can be obtained.

  When performing the deionization process, the control device 4 opens the first on-off valve 7a of the CDT 3 and closes the second on-off valve 7b of the CDT 3, and the liquid in the CDT 3 discharges the treated water. The opening / closing control of the valve is performed so that the flow to the passage 10 is achieved. And control which applies a DC voltage between both electrodes of CDT3 is performed. On the other hand, when the regeneration process is performed, the control device 4 closes the first on-off valve 7a of the CDT 3 and opens the second on-off valve 7b of the CDT 3, so that the liquid passing through the CDT 3 is discharged from the concentrated water. Valve opening / closing control is performed so that the flow to the path 8 is achieved. Then, the DC voltage applied during the deionization process between the electrodes of the CDT 3 is released, the anode side and the cathode side are short-circuited, or reversely connected, so that the ion component adsorbed on both electrodes is passed. Control to release into liquid.

  That is, the heavy metal wastewater treatment apparatus 1 contains an iron-based adsorbent that adsorbs the heavy metal ion component, and adsorbs an ion component in the heavy metal wastewater to the iron-based adsorbent, and the heavy metal adsorption. The apparatus 2 further removes the heavy metal ion component remaining in the heavy metal waste water on which the heavy metal ion component is adsorbed, and discharges the purified water from which the heavy metal ion component has been removed and the concentrated water from which the removed heavy metal ion component has been concentrated. And a circulating means for returning the concentrated water discharged from the CDT 3 to the heavy metal adsorbing device 2.

  The circulation means includes a deionization process and a regeneration process for the CDT 3, a control device 4 for controlling the first and second on-off valves 7a and 7b, the second communication pipe 6b, a second on-off valve 7b, and a concentration unit. It consists of a water discharge channel 8. In the regeneration process, the control device 4 closes the first on-off valve 7a and opens the second on-off valve 7b, thereby realizing the function as the circulating means. The discharged concentrated water can be returned to the heavy metal adsorption device 2.

  That is, the CDT 3 further removes the heavy metal ion component remaining in the heavy metal waste water from which the heavy metal ion component is adsorbed by the heavy metal adsorption device 2, and the purified water from which the heavy metal ion component has been removed and the removed heavy metal ion component. The concentrated concentrated water is discharged. The concentrated water discharged from the CDT 3 is returned to the heavy metal adsorbing device 2 and the concentrated heavy metal ion component is adsorbed by the iron-based adsorbent, and deionized.

  Thus, in the heavy metal wastewater treatment apparatus 1 and the heavy metal wastewater treatment method of the present invention, when treating heavy metal wastewater containing heavy metal ions, concentrated water enriched with heavy metal ions is not discharged at all. And the post-treatment process of the concentrated water is completely unnecessary, and the equipment for the post-treatment of the concentrated water, the maintenance of the equipment, the work accompanying them, etc. can be omitted completely. Therefore, the treatment cost of heavy metal wastewater can be greatly reduced, and the environmental burden due to the post-treatment of the concentrated water can be greatly reduced.

  Moreover, the heavy metal ion component contained in the heavy metal wastewater is adsorbed by the iron-based adsorbent of the heavy metal adsorption device 2 while the heavy metal wastewater circulates through the heavy metal adsorption device 2 and the deionization device. For this reason, the adsorption | suction waste material by which the heavy metal ion was adsorb | sucked can be utilized as an iron scrap raw material required in the case of steelmaking, can be melt | dissolved and it can reproduce | regenerate as an iron-type material. Thus, the post-treatment process of the adsorption waste material is completely unnecessary, and the equipment for post-treatment of the adsorbent material, the maintenance of the equipment, and the work accompanying them can be omitted completely. In addition, it is possible to use a relatively inexpensive adsorbent, such as an iron-based adsorbent, as a consumable, and to recycle the consumable. Therefore, the processing cost of heavy metal wastewater can be greatly reduced, the environmental load due to post-treatment of the adsorbed waste material can be greatly reduced, and the recyclability is excellent.

  As described above, the heavy metal wastewater treatment apparatus 1 and the heavy metal wastewater treatment method of the present invention completely eliminate the discharge of concentrated water and adsorb heavy metal ion components to the iron-based adsorbent, thereby greatly increasing the treatment cost of heavy metal wastewater. In addition to savings, it can greatly reduce the environmental burden due to post-treatment of concentrated water and adsorbed waste, and has excellent recyclability.

  In addition, the CDT 3 applies a DC voltage between the electrodes existing in the heavy metal waste water, thereby adsorbing the heavy metal ion component remaining in the heavy metal waste water to the both electrodes and discharging the heavy metal waste water as purified water. Heavy metal ion components adsorbed on both electrodes by releasing the DC voltage applied between the electrodes and the deionization process, short-circuiting the anode side and the cathode side, or reversely connecting them. Is discharged into the heavy metal wastewater, and the regeneration treatment is performed to discharge the heavy metal wastewater as concentrated water. For this reason, the heavy metal ion component remaining in the heavy metal wastewater by the deionization treatment can be adsorbed on both electrodes and discharged as purified water, and the heavy metal ion component adsorbed on the two electrodes by the regeneration treatment Can be discharged into the heavy metal wastewater to discharge the heavy metal wastewater as concentrated water.

  When the deionization process is performed in CDT3, the heavy metal ion components adhering to both electrodes are saturated and the adsorbing ability is reduced, so that the ion component adhering to both electrodes is released by performing the regeneration process. The ability can be restored. In this manner, heavy metal ion components adhering to both electrodes are saturated by performing deionization processing in CDT3, and concentrated water is discharged from heavy metal wastewater even if regeneration processing is performed in CDT3 because of the need to prevent a decrease in adsorption capacity. Since it is returned to the heavy metal adsorbing apparatus without being discharged outside the processing apparatus 1, it is possible to reduce the environmental load. Moreover, in the CDT 3, the heavy metal ions adsorbed by the deionization process are completely released by the regeneration process and discharged as concentrated water. The discharged concentrated water is adsorbed and removed by the iron-based adsorbent in the heavy metal adsorption device 2. Therefore, in such a heavy metal wastewater treatment device 1, the adsorption waste material including the removed heavy metal ions is only the iron-based adsorbent used in the heavy metal adsorption device 2, and no other adsorption waste material is generated. is there. Then, the adsorbed waste material on which the heavy metal ions are adsorbed can be dissolved and regenerated as an iron-based adsorbent without the concentrated water being discharged, and complete recycling can be achieved.

  Further, by using such CDT3, it is possible to remove heavy metal ion components remaining in the concentrated water without lowering the adsorptive capacity even if the concentrated water shows a high pH value due to adsorption by the iron-based adsorbent. Can do. Therefore, it is more suitable for the combination with the iron-based adsorbent, and it becomes an apparatus and a method that sufficiently exhibit the above-mentioned complete recycling.

  In the regeneration process of the present embodiment, the DC voltage applied during the deionization process may be canceled, or the anode side and the cathode side may be short-circuited (short-circuited). May be. The first on-off valve 7a and the second on-off valve 7b may be integrated. In this case, for example, the concentrated water discharge path that opens and closes the treated water discharge path 10 that discharges the treated water after the deionization process to the deionization apparatus 3 and discharges the concentrated water that contains the ionic components released in the regeneration process A two-way switching valve that opens and closes 8 may be provided. Although not shown, a predetermined voltage is supplied to each device such as the deionization device 3 and the control device 4. Further, so-called electromagnetic valves and air control valves may be used as the first and second on-off valves.

  Next, an example of the deionization process and regeneration process of the CDT 3 will be described with reference to FIG. FIG. 2A shows the deionization process, and FIG. 2B shows the regeneration process.

  As shown in FIG. 2A, when a voltage is applied, sodium ions in the inflow water (passing through the CDT 3) are electrically adsorbed on the activated carbon layer 33 in contact with the collector electrode 34 on the cathode side, and chlorine ions are It is electrically adsorbed by the activated carbon layer 33 in contact with the anode-side collector electrode 34. For this reason, the treated water obtained from the outlet has a significantly reduced sodium chloride concentration.

  Further, if water is continued for a long time, the adsorption of ions to the activated carbon layer 33 approaches saturation, so that the sodium chloride concentration of the treated water obtained from the outlet increases. Therefore, before reaching adsorption saturation, the anode side and the cathode side are short-circuited (short-circuited), the DC voltage applied during the deionization treatment between the electrodes on the anode side and the cathode side is canceled, or reverse connection ( If reverse voltage is applied), sodium ions and chlorine ions adsorbed on the activated carbon layer 33 are desorbed as shown in FIG. 2B, and contain sodium chloride at a concentration much higher than the sodium chloride concentration in the influent water. Outflow water (concentrated water) is discharged during the flow and discharged from the outlet. It is preferable to slow down the flow rate at this time because sodium chloride adsorbed on the activated carbon layer can be discharged with a small amount of flowing water.

  Although there is no restriction | limiting in particular in the deionization apparatus (CDT3) used for the heavy metal wastewater treatment apparatus of this invention, For example, the following two types can be mentioned as a representative example. As the deionizer, an activated carbon layer mainly composed of high specific surface area activated carbon is disposed as a high specific surface area conductor with a separator made of an electrically insulating porous liquid-permeable sheet interposed therebetween, and is collected outside the activated carbon layer. The thing of the flat plate shape which has the structure which has arrange | positioned an electrode and also has arrange | positioned the press plate on the outer side of the collector electrode is mentioned. By using a flat activated carbon layer and arranging the members into a flat plate structure that is pressed and pressed, the activated carbon layer can be evenly compressed and liquid drift during liquid passage can be effectively prevented. Therefore, the removal rate of the ionic substance can be stabilized and the removal rate can be increased to the limit.

  FIG. 3 shows an example of an exploded view of such a flat plate type deionization apparatus (referred to as “flat type electric deionization apparatus 31”), and FIG. 4 shows an assembly drawing thereof. is there. 3 and 4, parts that are the same as those in FIG. 2 are denoted by the same reference numerals. As the separator 32 of the flat plate type electric deionization device 31, a filter paper, a porous polymer membrane, a woven fabric, a non-woven fabric, or the like, which is made of an organic or inorganic sheet that easily allows liquid to pass therethrough and has electrical insulation properties. Used. The thickness of the separator 32 is preferably about 0.01 to 0.5 mm, particularly about 0.02 to 0.3 mm.

  As the activated carbon layer 33, a layer mainly composed of high specific surface area activated carbon is used. The high specific surface area activated carbon refers to activated carbon having a BET specific surface area of preferably 1000 m 2 / g or more, more preferably 1500 m 2 / g or more, and still more preferably 2000 to 2500 m 2 / g. When the BET specific surface area is too small, the removal rate of the ionic substance when the liquid containing the ionic substance is passed tends to decrease. If the BET specific surface area becomes too large, the removal rate of the ionic substance tends to decrease, so that it is not necessary to increase the BET specific surface area more than necessary. The shape of the activated carbon to be used is arbitrary, such as granular or fibrous. In the case of powder, it is preferably formed into a flat plate or sheet, and in the case of fiber, it is preferably processed into a cloth. The use of powdered activated carbon formed into a flat plate shape or a sheet shape is markedly advantageous in terms of cost compared to the case where fiber activated carbon is processed into a cloth shape. For forming into a flat plate or sheet, for example, powdered activated carbon is mixed with a binder component (polytetrafluoroethylene, phenol resin, carbon black, etc.) and / or a dispersion medium (solvent, etc.) to form a plate. From the above, it is obtained by appropriately heat-treating. In the case of using a plate-like or sheet-like one as the activated carbon layer 33, it can be perforated if necessary. The thickness of the activated carbon layer 33 is preferably about 0.1 to 3 mm, particularly about 0.5 to 2 mm, but is not necessarily limited to this range.

  The electrode such as the collector electrode 34 is preferably a good electrical conductor such as a copper plate, an aluminum plate, a carbon plate, or foil-like graphite and capable of intimate contact with the activated carbon layer 33. The thickness of the collector electrode 34 is not particularly limited, but is preferably about 0.1 to 0.5 mm. In order to facilitate the application, the collector electrode 34 is usually provided with a terminal (lead) 34a.

  As the presser plate 36, a flat plate made of an electrically insulating material such as a plastics plate which is not easily deformed is used. The holding plate 36 can be appropriately provided with a liquid inlet 37, a liquid outlet 38, a fixing bolt hole 39, and the like. It is desirable to interpose a frame-shaped gasket 35 between the collecting electrode 34 and the pressing plate 36. Instead of providing such a gasket 35 independently, a member having a sealing function can be provided on the holding plate 36 side. As shown in FIG. 3, using the above-described members, as shown in FIG. 3, presser plate 36 / (gasket 35 /) collector electrode 34 / activated carbon layer 33 / separator 32 / activated carbon layer 33 / collector electrode 34 / (gasket 35 /) presser plate 36. The flat plate type electric deionization apparatus 31 having the structure is assembled.

  Further, referring to FIG. 5, as an example of the above deionization apparatus, a schematic enlarged sectional view of a multi-treatment chamber type electric deionization apparatus (hereinafter referred to as “multi-treatment chamber type electric deionization apparatus 50”). Will be described.

  This multi-treatment chamber type electric deionization apparatus 50 includes two end plates 51 and 52 that are spaced apart from each other and two single-sided terminal electrodes 55 that are adjacent to each other with insulating layers 53 and 54 interposed therebetween. 56. Each of the single-sided terminal electrodes 55 and 56 has a sheet made of an activated carbon layer 64 of a conductor having a high specific surface area bonded to one side of a collector electrode made of a titanium sheet with a binder such as conductive epoxy. Double-sided intermediate electrodes 57 to 63 are disposed between the two single-sided terminal electrodes 55 and 56 so as to be separated from each other by an equal distance. Each double-sided electrode (for example, 57) is obtained by bonding an activated carbon sheet as an activated carbon layer 64 to both sides of a collector electrode made of a titanium sheet. The number of the intermediate electrodes is not limited, and is adjusted as appropriate so as to obtain a surface area capable of obtaining a necessary capacity (FIG. 5 shows only seven double-sided intermediate electrodes 57 to 63).

  Each electrode of the multi-processing chamber type electric deionization apparatus 50 having such a configuration is used as an anode and a cathode alternately. That is, for example, the single-sided terminal electrode 55 and the intermediate electrodes 58, 60 and 63 are used as anodes, and the intermediate electrodes 57, 59, 61 and 62 and the single-sided terminal electrode 56 are used as cathodes. Then, each adjacent electrode pair (anode and cathode) forms an independent processing chamber.

  Therefore, when heavy metal wastewater is introduced into the multi-treatment chamber type electric deionization apparatus 50, first, as shown by an arrow A, heavy metal wastewater that passes through the first treatment chamber 81 flows substantially parallel to the electrode surface. . Then, since the electrodes on both sides are polarized, ions are electrostatically removed from the heavy metal drainage and are held in the electric double layer formed on the surfaces of the activated carbon layers 64 of the electrodes 55 and 57.

  The heavy metal waste water then flows through the hole 80 and into the next processing chamber 82 as indicated by arrow B. Here, the ions in the heavy metal drainage are further removed by the polarization of the processing chamber formed by the intermediate electrodes 57 and 58. Then, the heavy metal drainage is continuously passed through the remaining processing chambers as indicated by arrows C to G, and ions are removed. Thereafter, as shown by an arrow H, the treated water passes through the single-sided terminal electrode 56, the insulating layer 54, and the like, and is led out from the multi-treatment chamber type electric deionization apparatus 50 through the outlet.

  As described above, the multi-treatment chamber type electric deionization apparatus 50 also removes various heavy metal ions including metal ions such as calcium and magnesium from the heavy metal waste water as in the flat plate type electric deionization apparatus 31. be able to. Then, by continuous operation, various ions are accumulated on the surface of the activated carbon layer 64 such as a porous carbon airgel sheet, the heavy metal ion component for deionization treatment is saturated, and removal of various ions contained in the heavy metal drainage is not possible. It becomes possible. Therefore, at an appropriate time, each electrode pair of [Anode]-[Cathode] is short-circuited, the DC voltage applied at the time of deionization between these electrodes is released, or deionization is applied to the electrode pair. A reverse voltage is applied to that during the treatment, and various ions accumulated on the surface of the porous activated carbon layer 64 are desorbed and regenerated. Then, after regeneration, the deionization process is performed again. Thereafter, the energization operation continuously applied to each electrode is repeated, the deionization treatment-regeneration treatment is repeated, and the operation is continued.

  Thus, by passing heavy metal drainage through the electric deionizer as described above and energizing the collector electrode, the ions in the heavy metal drainage are captured in the activated carbon layer having a high specific surface area and collected as treated water. is there. During this time, ions accumulate in the activated carbon layer such as high specific surface area activated carbon or porous carbon airgel composite, and the heavy metal ion component is saturated. A regeneration process is performed in which the voltage is released or a reverse voltage is applied to desorb ions accumulated in the activated carbon layer having a high specific surface area and exclude the ions from the apparatus. By repeating these operations, treated water is continuously obtained.

  Note that a so-called carbon aerogel may be used as the electrode. A carbon airgel layer may be used as the activated carbon layer. By using these, the adsorption area of the heavy metal ion component can be increased, the electrode will not dissolve in the liquid flow, and even if gas is generated by the regeneration treatment, the gas will not be adsorbed. There are merits such as not decreasing.

  In the present embodiment, the heavy metal wastewater treatment device 1 includes a reverse osmosis membrane device 91 instead of the CDT 3 shown in the first embodiment as the deionization device. The reverse osmosis membrane device 91 performs a reverse osmosis membrane treatment in which the heavy metal drainage adsorbed with the heavy metal ion component in the heavy metal adsorption device 2 is filtered through a reverse osmosis membrane to separate the purified water and the concentrated water. .

  The first communication pipe 6 a is provided with a high-pressure pump 93 that pressurizes and introduces the heavy metal drainage from which the heavy metal ion component is adsorbed in the heavy metal adsorption device 2 into the reverse osmosis membrane device 91. Thereby, the heavy metal waste water can be continuously supplied to the reverse osmosis membrane device 91. The treated water discharge channel 10 is connected to the reverse osmosis membrane device 91 so that the purified water separated from the heavy metal wastewater by the reverse osmosis membrane treatment of the reverse osmosis membrane device 91 is discharged from the treated water discharge channel 10. It has become. The concentrated water discharge path 8 is also connected to the reverse osmosis membrane device 91, and the concentrated water separated from the heavy metal wastewater by the reverse osmosis membrane treatment of the reverse osmosis membrane device 91 is transferred from the concentrated water discharge path 8 to the heavy metal adsorption device. Return to 2. Other than that, the second embodiment is the same as the first embodiment, and the same reference numerals are given to the same parts.

  With the configuration as described above, the purified water separated from the heavy metal wastewater by the reverse osmosis membrane treatment of the reverse osmosis membrane device 91 is discharged from the treated water discharge passage 10 connected to the reverse osmosis membrane device 91, and the reverse The purified water separated from the heavy metal wastewater by the osmosis membrane treatment is returned to the heavy metal adsorption device 2 from the concentrated water discharge path 8 connected to the reverse osmosis membrane device 91.

  That is, the deionization apparatus of the present embodiment performs a reverse osmosis membrane treatment in which the heavy metal wastewater adsorbed with heavy metal ion components in the heavy metal adsorption device 2 is filtered through a reverse osmosis membrane to separate the purified water and the concentrated water. Since it is the reverse osmosis membrane apparatus 91, it can be separated into purified water and concentrated water constantly by the reverse osmosis membrane treatment. This concentrated water is returned to the heavy metal adsorbing device 2 without being discharged to the outside of the heavy metal wastewater treatment device 1 by the circulation means (in this embodiment, the concentrated water discharge passage 8). can do.

  The reverse osmosis membrane device 91 may be a so-called tubular type, plate and frame type, spiral type, hollow fiber type, or the like. By using a tubular type or plate and frame type reverse osmosis membrane device. In heavy metal wastewater with a high concentration of heavy metal ions, it can be effectively separated into purified water and concentrated water. Further, by using a spiral type reverse osmosis membrane device as the reverse osmosis membrane device 91, it is possible to prevent the concentration of heavy metal ions contained in the heavy metal drainage from being biased, and it is possible to uniformly filter through the reverse osmosis membrane. Further, by using a hollow fiber type reverse osmosis membrane device as the reverse osmosis membrane device 91, an extremely large membrane area can be secured with a small volume.

  In each of the above embodiments, the heavy metal waste water may contain contaminants other than heavy metals and organic compounds. In addition to wastewater, it may be before wastewater, from the final disposal site (including landfills for solid waste such as municipal waste and industrial waste, various factories, etc.) It can be applied to various modes of water containing heavy metal ions, such as leached water. For example, the same purification effect can be obtained even when used for the purification of groundwater contaminated with heavy metals.

  If the heavy metal wastewater contains at least one of heavy metals such as arsenic, lead, cadmium, chromium, selenium and mercury, and harmful elements such as fluorine, boron and cyanide, the heavy metal wastewater treatment of the present invention By the apparatus 1 and the heavy metal wastewater treatment method, these contaminants can be effectively fixed, reduced, or rendered harmless. Moreover, even if it contains an organic compound that is difficult to treat and harmful, such as an organic chlorine compound, the present invention is effective and can be reduced and decomposed effectively.

It is a figure which shows the heavy metal waste water treatment equipment of 1st Example of this invention. It is a figure which shows the deionization process and regeneration process of electrostatic deionization. It is an expanded view of the flat plate type electric deionization apparatus of the 1st example of a deionization apparatus. It is sectional drawing of a flat plate type electric deionization apparatus. It is a typical expanded sectional view of the multi-processing chamber type electric deionization apparatus of the 2nd example of a deionization apparatus. It is a figure which shows the heavy metal waste water treatment equipment of a 2nd Example.

Explanation of symbols

1 Heavy metal wastewater treatment equipment 2 Heavy metal adsorption equipment 3 CDT
DESCRIPTION OF SYMBOLS 4 Control apparatus 5 Introducing pipe 6a 1st communicating pipe 6b 2nd communicating pipe 7a 1st on-off valve 7b 2nd on-off valve 8 Concentrated water discharge path 10 Treated water discharge path 31 Flat plate type electric deionization apparatus 32 Separator 33 Activated carbon layer 34 Collecting electrode 34a Terminal 35 Gasket 36 Holding plate 37 Liquid inlet 38 Liquid outlet 39 Fixing bolt hole 50 Multi-treatment chamber type electric deionizer 51 End plate 52 End plate 53 Insulating layer 54 Insulating layer 55 Single-sided terminal electrode 56 Single-sided terminal electrode 57 double-sided intermediate electrode 58 double-sided intermediate electrode 59 double-sided intermediate electrode 60 double-sided intermediate electrode 61 double-sided intermediate electrode 62 double-sided intermediate electrode 63 double-sided intermediate electrode 64 activated carbon layer 80 hole 81 processing chamber 82 processing chamber 91 reverse osmosis membrane device 93 high pressure pump

Claims (6)

A heavy metal wastewater treatment device for removing heavy metal ion components contained in heavy metal wastewater containing heavy metal ions,
An iron-based adsorbent that adsorbs the heavy metal ion component, and a heavy metal adsorbing device that adsorbs the ion component in the heavy metal wastewater to the iron-based adsorbent;
Further removing the heavy metal ion component remaining in the heavy metal drainage where the heavy metal ion component is adsorbed by the heavy metal adsorption device, purified water from which the heavy metal ion component has been removed, and concentrated water from which the removed heavy metal ion component has been concentrated, A deionizer that discharges
A heavy metal wastewater treatment apparatus, comprising: circulating means for returning the concentrated water discharged from the deionizer to the heavy metal adsorption apparatus.   The deionization apparatus applies a DC voltage between the electrodes present in the heavy metal wastewater to adsorb the heavy metal ion component remaining in the heavy metal wastewater to the electrodes and discharge the heavy metal wastewater as purified water. Heavy metal ion components adsorbed on both electrodes by releasing the DC voltage applied between the electrodes and the deionization process, short-circuiting the anode side and the cathode side, or reversely connecting them. The heavy metal waste water treatment apparatus according to claim 1, wherein the waste metal waste water is discharged into the heavy metal waste water and the heavy metal waste water is discharged as concentrated water.   2. The deionization apparatus performs a reverse osmosis membrane treatment in which heavy metal wastewater adsorbed with heavy metal ion components in the heavy metal adsorption device is filtered through a reverse osmosis membrane to separate the purified water and the concentrated water. The heavy metal wastewater treatment equipment described. A heavy metal wastewater treatment method for removing heavy metal ion components contained in heavy metal wastewater containing heavy metal ions,
By adsorbing the ionic component in the heavy metal wastewater to the iron-based adsorbent by a heavy metal adsorbing device containing an iron-based adsorbent that adsorbs the heavy metal ion component,
In the heavy metal adsorption device, the heavy metal ion component remaining in the heavy metal waste water on which the heavy metal ion component is adsorbed is further removed by a deionization device, and the purified water from which the heavy metal ion component has been removed and the removed heavy metal ion component are concentrated. Drained concentrated water,
A heavy metal wastewater treatment method, wherein the concentrated water discharged from the deionizer is returned to the heavy metal adsorption device.   In the deionization apparatus, by applying a DC voltage between the electrodes present in the heavy metal wastewater, the heavy metal ion components remaining in the heavy metal wastewater are adsorbed on both electrodes and the heavy metal wastewater is discharged as purified water. Heavy metal ion components adsorbed on both electrodes by releasing the DC voltage applied between the electrodes and the deionization process, short-circuiting the anode side and the cathode side, or reversely connecting them. The heavy metal wastewater treatment method according to claim 1, wherein a regeneration treatment is performed in which the heavy metal wastewater is discharged into the heavy metal wastewater and discharged as concentrated water.   2. The heavy metal according to claim 1, wherein the deionization device performs a reverse osmosis membrane treatment in which the heavy metal drainage adsorbed with the heavy metal ion component in the heavy metal adsorption device is filtered through a reverse osmosis membrane to separate the purified water and the concentrated water. Wastewater treatment method.

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