KR102414134B1 - High concentration ion concentrated water treatment system generated in sewage and wastewater treatment and reuse processes - Google Patents

Abstract

The present invention relates to a high-concentration ion-concentrated water treatment system generated by the wastewater treatment and reuse process, comprising: a CDI treatment tank that treats ionic inorganic pollutants from the inflow sewage and wastewater in an adsorption process; And CDI concentrated water discharged from the desorption process of the CDI treatment tank is introduced, carbon dioxide (CO ₂ ) is introduced, and a mineral fixation reaction is induced by pH adjustment or heating to induce magnesium carbonate (MgCO ₃ ) or calcium carbonate (CaCO ₃ ). A bioreactor comprising; a bioreactor configured in front of the CDI treatment tank; and an ion fixing tank in which the surplus sludge discharged from the bioreactor and the CDI concentrated water discharged from the mineral fixation tank are respectively introduced, and the ionic inorganic contaminants of the CDI concentrated water are subjected to an adsorption reaction with the surplus sludge; A dehydrator configured to receive the surplus sludge discharged from the ion fixing tank or the bioreactor and receive calcium carbonate recovered from the mineral immobilization reaction in the mineral fixation reactor to dehydrate the surplus sludge. characteristic.

Description

High concentration ion concentrated water treatment system generated in sewage and wastewater treatment and reuse processes

The present invention is generated in a wastewater treatment process such as a conventional biological (Biological) or biofilm reactor (Membrane Bio-reactor), or electrochemical desalination (CDI: Capacitive Deionization, ED: Electrodialysis) for reuse of wastewater treated water Magnesium carbonate (Mineral Sequestration) process to react the highly concentrated ionized water generated in the fusion process with bicarbonate ions (HCO ₃ ^- ) or carbonate ions (CO ₃ ^2- ) by dissolved carbon dioxide (CO ₂ ). Magnesium Carbonation) or calcium carbonate (Calcium Carbonation), etc. are generated and recovered to reduce the concentration of carbon dioxide in the atmosphere, which is a representative cause of global warming, and to recover useful resources from high-concentration sewage and wastewater concentrated water and reduce TDS concentration in concentrated water. It relates to a high-concentration ion-concentrated water treatment system that can minimize the effect of the salt concentration of the final biological process counter-current, and further promote zero wastewater discharge.

Water pollution is aggravated by industrialization and urbanization, and water demand is rapidly increasing, resulting in a shortage of available water. Drought and water pollution caused by climate change may further exacerbate the water shortage problem in the future.

In order to respond to this water shortage situation, the government enacted the Act on Promotion and Support of Water Reuse to promote sustainable use of water resources and is making efforts to secure various water resources. have.

First, in advanced sewage treatment, the main factors to be treated are organic and inorganic substances contained in sewage. As a result, pollutants were removed and treated through oxidation of organic matter during the metabolic process of microorganisms present in the reactor, nitrification and denitrification of incoming ammoniacal nitrogen, and adsorption of phosphorus.

However, in the case of the above-mentioned conventional advanced sewage treatment method, the concentration of organic matter (BOD: 5-10 mg/L, COD: 20-40 mg/L) and total nitrogen (20 mg/L) in the effluent water quality standards of public sewage treatment facilities can be solved with the existing biological process, but when the water temperature is lowered like in winter, the activity is greatly lowered and the nitrification efficiency is reduced accordingly. Since it is known that it is difficult to remove, there is a problem that chemical phosphorus removal using a coagulant must be added to the subsequent process after the phosphorus effluent water quality standard is strengthened. If ₄ ) is added, the existing bioprocess-based method has limitations in treatment.

In addition, in the case of chemical coagulants, which are generally applied due to the strengthening of total phosphorus (T-P) concentration regulations, aluminum (Al) or iron (Fe) ions are introduced into the water system in large amounts, which raises concerns about causing another type of environmental problem. have. Accordingly, in the sewage and wastewater treatment process, the electrochemical desalination (CDI: Capacitive Deionization, ED: Electrodialysis) fusion process is expected to secure stable total nitrogen (T-N) and total phosphorus (T-P) removal efficiency even when the water temperature decreases in winter. .

On the other hand, reuse of sewage and wastewater treatment water is a relatively simple treatment method and can reduce the amount of pollution load discharged to public waters, but there are also concerns about the psychological rejection of reused water or the occurrence of inorganic substances such as incombustible organic substances or heavy metals. have.

In addition, if you want to reuse wastewater treated water as industrial water, etc., it is absolutely necessary to remove inorganic ions of various components in water. (RO) or electrochemical desalination (CDI, ED) or ion exchange resin (IEX) or more complex processes must be applied.

In addition, when reprocessing wastewater treated water for reuse, various processes such as physicochemical treatment including electrochemical desalination process, biological treatment, or combination treatment combining these are applied according to the target water quality required by the customer. However, in such a water treatment process, concentrated water containing high concentrations of salt, nitrogen, ionic substances, etc. is inevitably generated.

In general, such concentrated water treatment is returned to the front end of the sewage treatment plant for reprocessing, but when concentrated water with high concentration is treated in connection with the sewage treatment plant, it acts as an additional load to the sewage treatment and causes many problems in stable biological sewage treatment. , especially high salinity concentration causes protoplasmic separation in microorganisms, which causes a decrease in intracellular function and leads to cell destruction. .

In particular, high-concentration concentrated water generated during the wastewater treatment and reuse process includes ammonium (NH ₄ ⁺ ), calcium (Ca ^{2 +} ), magnesium (Mg ^{2 +} ), sodium (Na ⁺ ), potassium (K ⁺ ), etc. As resources such as cations and phosphate (PO ₄ ^3- ), ions valuable for recovery are abundantly dissolved, and the need to recover them as resources and reuse them is increasing.

At the same time, in order to cope with the increasingly serious climate change and global warming caused by greenhouse gases, various carbon dioxide (CO ₂ ) capture, storage and conversion utilization (CCS: Carbon Dioxide Capture and Storage, CCU: Carbon Dioxide Capture and Utilization) technologies have been developed. A lot of research is being done about it, and mineral carbonation (or carbonate mineralization, carbonate immobilization) technology is known as an effective CCS technology for capturing and storing CO ₂ generated in power plants and chemical plants.

However, it is difficult to secure economic feasibility in terms of management costs (transportation cost, extraction cost, etc.) to secure the metal salt required for reaction with carbon dioxide (CO ₂ ), so it is still in the basic research stage. Until now, research using metal salts (Ca ²⁺ , Mg ²⁺ , etc.) present in large amounts in sewage and wastewater for the purpose of capturing carbon dioxide (CO ₂ ) has not been studied. Because there are financial difficulties.

Meanwhile, the aforementioned electrochemical desalination (CDI, ED) technology is a technology that separates only dissolved ionic contaminants using the electric field principle in terms of water treatment, but in terms of the capture and storage of carbon dioxide (CO ₂ ) and the mineral carbonation process using it In the case of the electrochemical desalination (CDI, ED) technology, metal salts (Ca ^{2 +} , Mg ^{2 +} , K ⁺ etc.) and alkali ions (OH ^- , HCO ₃ ^- , CO ₃ ² - ) is separated/extracted/concentrated, so metal salts and alkali ions in high-concentration ion-concentrated water generated in the process of wastewater treatment and reuse using the electrochemical desalination (CDI, ED) technology are converted to carbon dioxide (CO ₂ ) in conjunction with CCS or CCU technology, effective sewage and wastewater treatment and reuse, resource reuse through metal salt recovery, and further reduction of carbon dioxide concentration in the atmosphere can be realized at the same time.

Republic of Korea Patent Publication No. 10-2015-0085983 (2015.07.27.) Republic of Korea Patent Registration No. 10-1734112 (2017.05.02)

Therefore, an object of the present invention is electrochemical desalination (CDI: Capacitive Deionization, ED: Electrodialysis) Mineral sequestration process that allows the high concentration of ion-concentrated water generated in the fusion process to react with bicarbonate ions (HCO ₃ ^- ) or carbonate ions (CO ₃ ^2- ) by dissolved carbon dioxide (CO ₂ ) Reduces the concentration of carbon dioxide in the atmosphere, a major cause of global warming, by generating and recovering Magnesium Carbonation or Calcium Carbonation with It is to provide a high-concentration ion-concentrated water treatment system that can reduce the concentration and minimize the effect of the salt concentration of the final biological process countercurrent, and further promote no discharge of wastewater.

As a means for achieving the above object, the high-concentration ion-concentrated water treatment system (hereinafter referred to as the "system of the present invention") of the present invention for wastewater treatment and reuse process adsorbs ionic inorganic contaminants from wastewater CDI treatment tank treated in the process; And CDI concentrated water discharged from the desorption process of the CDI treatment tank is introduced, carbon dioxide (CO ₂ ) is introduced, and a mineral fixation reaction is induced by pH adjustment or heating to induce magnesium carbonate (MgCO ₃ ) or calcium carbonate (CaCO ₃ ). It is characterized by including a; mineral fixation reaction tank for generating and precipitating.

As an example, a power storage device for recovering and storing electrical energy generated in the desorption process of the CDI treatment tank; and a heating means for receiving electric energy from the power storage device and heating the mineral fixing reaction tank.

As an example, a bioreactor configured in front of the CDI treatment tank; and an ion fixing tank in which the surplus sludge discharged from the bioreactor and the CDI concentrated water discharged from the mineral fixation tank are respectively introduced, and the ionic inorganic contaminants of the CDI concentrated water are subjected to an adsorption reaction with the surplus sludge; characterized by including.

As an example, it is interposed between the CDI treatment tank and the mineral fixation reaction tank, the CDI concentrated water discharged from the desorption process in the CDI treatment tank flows in, and the ED concentrated water treated by the electrodialysis method. and an ED treatment tank for discharging the discharged ED concentrated water to the mineral fixing reaction tank; characterized in that it further comprises.

As an example, it is characterized in that the dehydrator is further configured to receive the surplus sludge discharged from the ion fixing tank or the bioreactor and receive the calcium carbonate precipitated in the mineral fixation tank to perform dehydration treatment.

As such, the system of the present invention provides stable nitrogen (TN), phosphorus (TP) treatment or sewage/wastewater treatment without the influence of winter water temperature in a sewage and wastewater treatment process such as a conventional biological or membrane bio-reactor. Bicarbonate ions (HCO ₃ ^- ) or carbonate ions (CO ₃ ) by using dissolved carbon dioxide (CO ₂ ) in high-concentration ion-concentrated water generated in the electrochemical desalination (CDI: Capacitive Deionization, ED: Electrodialysis) fusion process for reuse of treated water. ^2- ) by generating and recovering magnesium carbonate or calcium carbonate through the Mineral Sequestration process to react with By reducing the TDS concentration in the concentrated water and the recovery of useful resources from the highly concentrated sewage and wastewater concentrate, it is possible to minimize the effect of the salt concentration of the final biological process return water, and furthermore, there is an advantage in that it is possible to promote no discharge of the wastewater.

In addition, the high-concentration ion-concentrated water generated in the process of wastewater treatment and reuse by minimizing the discharge of ionic substances by allowing the residual high-concentration ion-concentrated water to react with the high-concentration microorganisms in the sludge to be finally discarded as sludge. There is an advantage in that the reduction of ionic substances and the treatment thereof can be made easier, and as a result, sewage and wastewater treatment water can be efficiently reused.

In addition, the electrical energy generated during the regeneration process of the electrochemical desalination (CDI) treatment tank is recovered and stored so that it can be reused within or outside the system, as well as the mineral resources generated by the mineral immobilization process of high-concentration ion-rich water outside the system or outside the system. By allowing it to be reused in the water treatment process within the system, there is an advantage in that it is possible to reduce the resources and energy consumed in the operation of the system and the corresponding cost.

1 is a block diagram showing a basic example of the present invention;
2 is a block diagram illustrating an embodiment of the present invention;
3 and 4 are data showing the mineral carbonation reaction mechanism of the mineral fixing reaction tank.
5 is a graph showing the solubility according to the temperature and pH of carbon dioxide (CO ₂ ) for inducing a mineral carbonation reaction.
6 is a block diagram showing another embodiment of the present invention.

Hereinafter, the configuration and operation of the present invention will be described in more detail based on the accompanying drawings. In describing the present invention, the terms or words used in the present specification and claims are based on the principle that the inventor can appropriately define the concept of the term in order to best describe his or her invention. It should be interpreted as meaning and concept consistent with the technical idea of

Referring to FIG. 1 , the system 1 of the present invention is a CDI treatment tank 2 that treats ionic inorganic pollutants from wastewater in an adsorption step and discharges from a desorption process of the CDI treatment tank 2 The CDI concentrated water is introduced, and carbon dioxide (CO ₂ ) is introduced, and a mineral fixation reaction is induced by pH adjustment or heating to produce and precipitate magnesium carbonate (MgCO ₃ ) or calcium carbonate (CaCO ₃ ). is comprised of

In the CDI treatment tank 2, treated water from which organic matter has been removed from wastewater may be introduced. For example, a bioreactor 6 is provided at the front end of the CDI treatment tank 2 so that the treated water from which organic matter is separated and removed through the biological reaction of the bioreactor 6 flows into the CDI treatment tank 2 .

The bioreactor 6 according to an embodiment of the present invention removes organic matter from wastewater, which is previously introduced from the front end of the CDI treatment tank 2, and discharges surplus sludge including organic matter generated during the treatment. do.

The surplus sludge discharged from the bioreactor 6 may be intermittently or continuously transferred to the ion fixation tank 8 described below through the sludge transfer line, and the CDI treatment tank introduced into the ion fixation tank 8 ( 20) reacts with the CDI-concentrated water to enable bioadsorption.

In this case, the surplus sludge may be sludge drawn periodically in order to maintain a constant concentration of the sludge in the bioreactor 6 .

Such a bioreactor 6 is to create an environment capable of inducing a biological reaction from wastewater to separate and remove organic matter, and can be implemented in various ways through known techniques.

For example, the bioreactor 6 may be an aerobic reactor in which organic components in the inflow sewage are removed by microbial metabolism through an aerobic process.

The aerobic reactor utilizes activated sludge to deliver the treated water from which organic substances are removed in the inflow sewage to the CDI treatment tank 2 to be described below, and the ions present in the treated water from which the organic substances have been removed in the CDI treatment tank 2 Ammonia nitrogen and partially nitrified nitrate nitrogen components and phosphorus in the form of PO ₄ -P can be removed through electrosorption.

The bioreactor 6 may be an MBR (Membrane Bio-reactor) reactor in which a membrane having a separation membrane structure is provided, although not shown in the drawings for more efficient removal of particulate organic matter.

The CDI treatment tank 2 removes TDS (Total Dissolved Solid) and ionic inorganic contaminants present in the treated water flowing in from the bioreactor 6 by an electro-adsorption method using an electric field principle, and ionic inorganic contaminants Discharge of treated water from which contaminants, etc. have been removed.

Although not shown in the drawings, the CDI processing tank 2 may include one or more CDI modules in which a plurality of positive and negative electrodes are stacked at regular intervals and a power supply module for supplying power to the CDI modules.

And the CDI treatment tank 2 adsorbs and discharges the ionic contaminants present in the influent flowing between the positive electrode and the negative electrode. The desorption process for regeneration may be repeated at least twice or more, and in this process, CDI-concentrated water enriched with ionic contaminants may be selectively discharged.

Mineral resources such as magnesium carbonate (MgCO ₃ ) or calcium carbonate (CaCO ₃ ) can be recovered in the mineral fixing reaction tank 3 using CDI concentrated water separated and discharged through the desorption process of the CDI treatment tank 2 . let it be

That is, in the regular mineral fixing reaction tank 3, the mineral immobilization reaction between the high concentration of ion-concentrated water containing mineral ions such as Ca ^{2 +} , Mg ^{2 +} and dissolved carbonic acid in the form of H ₂ CO ₃ or HCO ₃ ^- or CO ₃ ^2- By induction, magnesium carbonate (MgCO ₃ ) or calcium carbonate (CaCO ₃ ) can be produced.

The mineral fixation reaction tank 3 crystallizes magnesium carbonate (MgCO ₃ ) or calcium carbonate (CaCO ₃ ) and precipitates it by controlling the pH or warming the environment of the reaction tank while introducing the CDI-enriched water and carbon dioxide (CO ₂ ) from the outside. can be recovered as mineral resources.

To this end, the mineral fixing reaction tank 3 is not shown in the drawings, but may include a gas injection device for artificially injecting carbon dioxide (CO ₂ ). By this gas injection device, carbon dioxide (CO ₂ ) is introduced. This increases the reaction rate of the mineral immobilization reaction and increases the purity of the produced magnesium carbonate (MgCO ₃ ) or calcium carbonate (CaCO ₃ ).

Here, the carbon dioxide (CO ₂ ) is present at a concentration of about 300-400 mg/L and has a high solubility of 1.4-1.5 g/L (room temperature, atmospheric pressure), or carbon dioxide (CO ₂ ) in the atmosphere, or around a wastewater treatment plant It is desirable to reduce carbon emissions by using high-concentration carbon dioxide (CO ₂ ) collected from exhaust gases emitted from facilities such as incineration facilities, gas power plants, and carbonization processes, and to induce the mineral immobilization reaction In the warming environment, waste heat from facilities such as incineration facilities, gas power plants, and carbonization processes in the vicinity of the wastewater treatment plant can be utilized.

According to another embodiment of the present invention, the heating environment for the mineral fixing reaction tank (3) can utilize the electrical energy generated in the desorption process of the CDI treatment tank (2).

As shown in FIG. 2, in the system according to this embodiment, a power storage device 4 for recovering and storing electrical energy generated in the desorption process of the CDI treatment tank 2, and electrical energy from the power storage device 4 It may further include a heating means (5) for heating the mineral fixing reaction tank (3) by receiving the.

That is, the CDI treatment tank 2 repeatedly performs a desorption process on the electrode to generate CDI-enriched water as mentioned above. In this process, the electric energy discharged from the electrode is recovered and the power storage device 4 ), and the electrical energy stored in the power storage device 4 is used as an energy source for the heating means 5 .

In this case, the heating means 5 may select one suitable from among various known heating devices that can generate heat by electric energy, such as an electric heater coil and an electric hot air fan.

In addition, in the case of the power storage device 4, it is preferable to use a battery connected to an ESS (Energy storage system) for solar power installed in a sewage and wastewater treatment plant as the power storage device 4, and accordingly, a separate new It is possible to recover and reuse the energy of the CDI treatment tank (2) with simple wiring work without facilities.

A detailed description of the mineral immobilization reaction and resource recovery of the mineral fixation reaction tank 3 will be described again below.

On the other hand, the system of the present invention enables stable nitrogen and phosphorus treatment without the influence of winter water temperature through the bioprocess fusion electrosorption (CDI) process described above, and the reactor capacity and site through the operation of the aerobic-centered bioreactor 6 It is possible to expect reduction of equipment and maintenance costs through reduction of air consumption, pump equipment for liquid transfer between anaerobic/aerobic reactors, and air consumption for the existing nitrification process.

However, in the CDI treatment tank 2 in which the electro-adsorption is performed, the adsorption and desorption of ionic contaminants are repeated several times to generate high-concentration ion-concentrated water, which must be treated.

Accordingly, in the system of the present invention, as shown in FIG. 6 , the surplus sludge discharged from the bioreactor 6 and the CDI concentrated water discharged after the recycling reaction in the mineral fixing reaction tank 3 are respectively introduced, and the CDI concentrated water It may further include an ion fixing tank (8) for the ionic inorganic pollutants of the surplus sludge and the adsorption reaction is made.

The ion fixation tank 8 includes high-concentration ion-concentrated water generated in the CDI treatment tank 2 or high-concentration ion-concentrated water discharged through the mineral resource recovery process of the mineral fixation tank 3, and the bioreactor 6 Bio-sorption of the excess sludge by high-concentration microorganisms is induced by mutually reacting the discharged surplus sludge to keep the concentration of microorganisms constant, and then finally discarded as sludge.

Specifically, the ion fixation tank 8 flows in each of the surplus sludge discharged from the bioreactor 6 and the CDI concentrate discharged from the CDI treatment tank 2 or the mineral fixation tank 3 so that they can react. do.

In addition, the ion fixing tank 8 induces a reaction such that the ionic inorganic contaminants of the CDI-enriched water are adsorbed on the surface or inside of the organic or inorganic substances contained in the surplus sludge, thereby reducing the ion concentration of the stored CDI-concentrated water. The surplus sludge adsorbed with the ion component is precipitated in the storage tank so that it can be separated and discharged later through a sludge transport vehicle, etc.

In organic matter separated through biological treatment, in vitro polymer materials of microorganisms have specific ionic properties and have been studied to have adsorption performance to adsorb ionic substances, NH ₄ ⁺ -N, NO ₃ ^- -N, The CDI-enriched water containing ionic nutrients such as PO ₄ ^3- -P can be bioadsorbed to the surface of the organic matter of the surplus sludge during the storage process of the ion fixing tank 8 .

At this time, the operating conditions of the ion fixation tank 8, for example, the flow rate and timing of the surplus sludge and CDI concentrated water drawn from the bioreactor 6, the pH conditions, and the addition of a coagulant to increase the ion fixation efficiency It is desirable to selectively set the drug and the like according to the results of the removal characteristics of ionic nutrients accumulated in the past so that the optimal bioadsorption performance can be derived.

In addition, the ion fixing tank 8 separates and discharges the surplus sludge settling through the sedimentation process and returns the supernatant water from the ion fixing tank 8 to the bioreactor 6, so that of the bioreactor 6 to reduce the operating load.

Although the ion fixing tank 8 is not shown in the drawing, a plurality of treatment tanks such as a control tank, a reaction tank, and a sedimentation tank may be provided to increase the efficiency of the bioadsorption reaction, and these plurality of treatment tanks may be operated separately. Of course.

As such, in the system of the present invention, only ionic nutrients are bioadsorbed to the surplus sludge and discarded together without requiring a complex treatment process and consequent high cost in treating the high-concentration CDI-concentrated water. There is an effect that it can be easily processed.

Here, the sludge discharged from the ion fixing tank 8 or the bioreactor 6 may be finally caked and discharged through the dehydration treatment of the dehydrator 9. In this process, a dehydrating agent or dehydration agent for more efficient dehydration treatment Medications such as supplements may be administered.

The present invention provides an example in which calcium carbonate (CaCO ₃ ) recovered as a mineral resource in the mineral fixation reaction tank 3 is utilized as the dehydrating agent or dehydration aid, and the dehydrator 9 is the ion fixation tank ( 8) Alternatively, the surplus sludge discharged from the bioreactor 6 is supplied and calcium carbonate (CaCO ₃ ) is supplied among the resources recovered from the mineral fixation reaction in the mineral fixation reaction tank 3 so that the dehydration of the surplus sludge is performed. By doing so, the operating cost required for dewatering treatment can be reduced.

In addition, the system of the present invention is interposed between the CDI treatment tank 2 and the ion fixation tank 30 as shown in FIG. 6 , and the CDI concentrated water discharged from the CDI treatment tank 20 flows in and flows in The ED concentrated water is discharged by treating the CDI concentrated water in an electrodialysis method, and an ED treatment tank 7 for allowing the discharged ED concentrated water to flow into the mineral fixing reaction tank 3 is further included.

That is, in the system of the present invention, the ED treatment tank 7 is provided to generate ED concentrated water in which the ion concentration of the CDI concentrated water is further concentrated. ), that is, to minimize the unit area of the ion fixing tank 8 .

The ED treatment tank 7 recovers the CDI-concentrated water discharged during the desorption process in which the electrode is regenerated by desorbing the ions from the CDI treatment tank 2, and the CDI-concentrated recovered through the electrodialysis method. The ions are separated from the water, and the ED treated water in which the ions are separated and the ED concentrated water in which the ionic inorganic contaminants are more concentrated in the process are separated and discharged.

In this case, the ED treatment tank 7 is configured to supply the ED treatment water treated with ions to the CDI treatment tank 2 to be used as regeneration water in the desorption process of the CDI module, or as shown in FIG. 6 . Likewise, it may be combined with the treated water treated from the CDI treatment tank 2 and discharged.

Although not shown in the drawing, the ED treatment tank 7 includes at least one dilution chamber in which CDI-concentrated water flows in and ions in the CDI-concentrated water are removed and at least one concentration chamber in which ions are separated and collected, and the ED treatment of the dilution chamber The water and the ED concentrated water in the enrichment chamber are separately discharged, but the ED concentrated water in the enrichment chamber is configured to flow into the mineral fixing reaction tank (3).

In particular, the CDI treatment tank 2 and the ED treatment tank 7 are interconnected through a circulation line to undergo circulation and desalination treatment at least twice or more. In this way, the CDI treatment tank 2 and the ED treatment tank ( 7) Through the repeated circulation process in the liver, the ED re-concentrated water with more ion concentration is introduced into the mineral fixation reaction tank (3).

That is, the ED re-concentrated water discharged from the ED treatment tank 7 can be re-concentrated up to 50 to 90% depending on the concentration of the CDI concentrated water flowing into the ED treatment tank 7, and the CDI treatment tank 2 The volume of the concentrated water that finally flows into the mineral fixing reaction tank 3 is further reduced compared to the CDI concentrated water generated in the .

As described above, in the present invention, the volume and amount of concentrated water flowing into the mineral fixation tank 3 is minimized, so that the concentrated water that has undergone the mineral resource recovery process of the mineral fixation tank 3 is delivered to the ion fixation tank 8 of The volume can also be minimized, and the bioadsorption reaction of the ion fixation tank 8 can be more active and promoted due to the more concentrated concentrated water, and in particular, the density change of the surplus sludge accommodated in the ion fixation tank 8 is minimized. make it possible

On the other hand, the mineral fixation reaction tank (3) is the CDI concentrated water or ED re-concentrated water is introduced from the CDI treatment tank (2) or the ED treatment tank (7), in addition, carbon dioxide (CO ₂ ) Inflow and pH adjustment of the reaction tank or By inducing a mineral immobilization reaction through heating of the reactor, resources such as magnesium carbonate (MgCO ₃ ) or calcium carbonate (CaCO ₃ ) are generated and recovered.

Specifically, in the system of the present invention, carbon dioxide (CO ₂ ) is introduced into the mineral fixing reaction tank 3 by using the above-described gas injection device, etc., without injecting high-concentration liquefied carbon dioxide, which is economically low, and around the wastewater treatment plant. It is preferable to use carbon dioxide (CO ₂ ) collected from exhaust gas emitted from facilities such as incineration facilities, gas power plants, and carbonization processes.

More preferably, the highly concentrated dissolved carbonic acid (HCO ₃ ^- ) contained in the CDI or ED re-concentrated water is used as much as possible, and as the mineral immobilization reaction proceeds, the dissolved carbonic acid present in the water is consumed in the atmosphere. It is preferable to effectively reduce carbon dioxide (CO ₂ ) in the atmosphere by re-dissolving carbon dioxide (CO ₂ ) present in a high concentration of about 300 to 400 mg/L through a simple gas-liquid contact reactor.

This is because the volume of the concentrated ionized water generated after the electrochemical desalination process is very small, about 10% or less compared to the inflow sewage and wastewater, and the solubility of carbon dioxide (CO ₂ ) in the atmosphere is lower than that of other nitrogen (N2) or oxygen (O2). ) because it has a high solubility of about 1.4 to 1.5 g/L at room temperature and under normal pressure, as shown in FIG. 5 . In addition, it has a higher solubility in the pH range in the alkaline region for the mineral immobilization reaction.

So that mineral ions such as magnesium (Mg ⁺² ) or calcium (Ca ⁺² ) can be eluted and precipitated from the CDI concentrated water or ED re-concentrated water flowing in from the CDI treatment tank (2) or the ED treatment tank (7) , and gradually increase the pH concentration.

That is, as shown in FIG. 3, the pH of the CDI concentrated water or the ED re-concentrated water is in the range of about 7 to 8, and the alkalinity is mostly in the form of hydrogen carbonate ions (HCO ₃ ⁻ ). In the case of these hydrogen carbonate ions, the pH When it rises above 8, it is changed to carbonate ions (CO ₃ ^2- ). In order to induce a mineral fixation reaction, alkalinization of the pH is required.

According to an embodiment of the present invention, the pH increase for the mineral immobilization reaction may be achieved by adding an alkali solution to the mineral immobilization reaction tank 3, wherein the alkali solution may be sodium hydroxide (NaOH).

At this time, it is preferable that the range of the pH increased by the alkaline solution is 8.5 to 13.5.

In addition, the sodium hydroxide (NaOH) may be directly added, but preferably by using OH- ions obtained through electrolysis of concentrated water, it is possible to induce a mineral immobilization reaction without a separate external input.

When the pH is raised in this way, magnesium or calcium in the CDI-concentrated water or ED re-concentrated water is converted into Mg(OH) ₂ in the mineral fixing reaction tank (3). Alternatively, Ca(OH) ₂ is precipitated, and the precipitated magnesium or calcium is separated from concentrated water by filtration, and water is added thereto and stored in a suspension state. When water is added, magnesium or calcium is dissolved again and maintained in an ionic state.

And when carbon dioxide (CO ₂ ) is injected into the suspension in which magnesium or calcium is melted and the ionic state is maintained, a mineral immobilization reaction is performed, and gaseous carbon dioxide (CO ₂ ) is converted into carbonate ions and carbonized as shown in the reaction equation below. process will be carried out.

CO ₂ (g) + H ₂ O(l) ⇔ H ₂ CO ₃ (aq)

H ₂ CO ₃ (aq) ⇔ HCO ₃ ^- (aq) + H ⁺ (aq)

HCO ₃ ^- (aq) ⇔ CO ₃ ^2- + H ⁺ (aq)

That is, gaseous carbon dioxide (CO ₂ ) is dissolved, the dissolved carbon dioxide (CO ₂ ) reacts with water to form carbonic acid, and carbonic acid is decomposed into hydrogen and carbonate ions (CO ₃ ^2- ).

And calcium carbonate (CaCO ₃ ) can be separated and generated by the following reaction formula.

Ca ^{2 +} + 2CO ₂ + H ₂ O → Ca ^{2 +} + 2HCO ₃ ^- + H ₂ O

→ CaCO ₃ + H ₂ O + 2H ⁺

In addition, magnesium carbonate (MgCO ₃ ) may be separated and generated by the following reaction formula in the state in which carbonate ions (CO ₃ ^2- ) are formed.

Mg ^{2 +} + CO3 ^2- → MgCO ₃

That is, magnesium or calcium is precipitated in the form of carbonate through the mineral immobilization reaction of the mineral fixing reaction tank 3, and they do not dissolve again and maintain a stable state, so that carbon dioxide (CO ₂ ) is fixed, filtered and precipitated, and magnesium carbonate (MgCO) ₃ ) or by being able to produce minerals such as calcium carbonate (CaCO ₃ ), these minerals can be recycled.

In the case of calcium carbonate (CaCO ₃ ) among minerals separated from the mineral immobilization reaction of the mineral fixation reaction tank 3 in this way, as described above, it is added during the dehydration process of the dehydrator 9 and can be used as a dehydrating agent or a dehydration aid.

Those skilled in the art from the above description will be able to see that various changes and modifications are possible without departing from the technical spirit of the present invention. Accordingly, the technical scope of the present invention should not be limited to the content described in the detailed description of the specification, but should be defined by the claims.

1: System of the present invention 2: CDI treatment tank
3: mineral fixation reaction tank 4: power storage device
5: heating means 6: bioreactor
7: ED treatment tank 8: ion fixing tank
9: Dehydrator

Claims (5)

a CDI treatment tank that treats inorganic ionic pollutants from wastewater in an adsorption process; and
CDI concentrated water discharged from the desorption process of the CDI treatment tank is introduced, carbon dioxide (CO ₂ ) is introduced, and a mineral fixation reaction is induced by pH adjustment or heating to produce magnesium carbonate (MgCO ₃ ) or calcium carbonate (CaCO ₃ ) and a mineral fixation reaction tank for precipitation;
a bioreactor configured in front of the CDI treatment tank; and
Excess sludge discharged from the bioreactor and CDI concentrated water discharged from the mineral fixation tank are respectively introduced, and the ionic inorganic contaminants of the CDI concentrated water are subjected to an adsorption reaction with the surplus sludge; further includes; do,
A dehydrator configured to receive excess sludge discharged from the ion fixation tank or the bioreactor and receive calcium carbonate recovered from the mineral fixation reaction in the mineral fixation tank to dehydrate the surplus sludge ·Wastewater treatment and reuse process generated high-concentration ion-concentrated water treatment system.
The method of claim 1,
a power storage device for recovering and storing electrical energy generated in the desorption process of the CDI treatment tank; and
High-concentration ion-concentrated water treatment system generated by the wastewater treatment and reuse process, characterized in that it further comprises a; heating means for heating the mineral fixing reaction tank by receiving electrical energy from the power storage device.
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It is interposed between the CDI treatment tank and the mineral fixation tank, and the CDI concentrated water discharged during the desorption process from the CDI treatment tank is introduced, and the ED concentrated water treated by the electrodialysis method is discharged. , ED treatment tank for allowing the discharged ED concentrated water to flow into the mineral fixing reaction tank; Sewage and wastewater treatment and reuse process generated high concentration ion-enriched water treatment system, characterized in that it further comprises.
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