KR102515113B1 - Concentrated water treatment system using ion fixation - Google Patents

Abstract

The present invention can minimize the capacity and site of the reaction tank and additional processes without the need for various facilities required for the individual operation of the existing anaerobic / aerobic reaction and nitrification reaction by fusion operation of the aerobic-centered biological process and the electrosorption process. In particular, bioadsorption by highly concentrated microorganisms ( It relates to a high-concentration concentrated water treatment system using ion fixation that facilitates the treatment of high-concentration concentrated water generated in the electrosorption process by finally disposing of it as sludge after inducing bio-sorption). A system comprising a bioreactor for biologically treating wastewater to remove organic matter and a CDI treatment tank for adsorbing and treating ionic inorganic contaminants contained in the treated water into which the treated water flows in the bioreactor, wherein the bioreactor An ion fixation tank into which the excess sludge discharged from the CDI treatment tank and the concentrated CDI water discharged from the CDI treatment tank are respectively introduced, and the ionic inorganic contaminants in the concentrated CDI water are adsorbed with the excess sludge. am.

Description

Concentrated water treatment system using ion fixation {Concentrated water treatment system using ion fixation}

The present invention can minimize the capacity and site of the reaction tank and additional processes without the need for various facilities required for the individual operation of the existing anaerobic / aerobic reaction and nitrification reaction by fusion operation of the aerobic-centered biological process and the electrosorption process. In particular, bioadsorption by highly concentrated microorganisms ( It relates to a high-concentration concentrated water treatment system using ion fixation that facilitates the treatment of high-concentration concentrated water generated in an electrosorption process by finally disposing of it as sludge after inducing bio-sorption.

Due to industrialization and urbanization, water pollution is aggravated and demand for water is rapidly increasing, and usable water is becoming scarce, and drought and water pollution caused by climate change may further intensify the water shortage problem in the future.

In order to respond to this water shortage situation, the government has enacted laws on the promotion and support of water reuse to promote sustainable use of water resources, and is making efforts to secure various water resources, and reuse of sewage treatment water is being presented as a realistic alternative.

First of all, in advanced sewage treatment, the main treatment target factors are organic and inorganic components contained in sewage, and the most common treatment method is to divide an anaerobic reaction tank (anoxic tank) and an aerobic reaction tank and alternate anaerobic / aerobic oxidation reactions During the metabolic process of microorganisms in the reaction tank, pollutants were removed and treated through oxidation of organic matter, nitrification and denitrification of inflow ammonia nitrogen, and adsorption of phosphorus.

However, in the case of the conventional advanced sewage treatment method described above, the organic matter (BOD: 5-10 mg/L, COD: 20-40 mg/L) and total nitrogen (20 mg/L) concentrations among the current effluent water quality standards of public sewage treatment facilities can be solved with the existing bioprocess, but when the water temperature decreases, such as in the winter season, the activity is significantly lowered, resulting in a decrease in nitrification efficiency. Since it is known that it is difficult to remove phosphorus, there is a problem that chemical phosphorus removal using a flocculant must be added to the subsequent process after phosphorus effluent water quality standards have been strengthened. ) is added, the existing bioprocess-based method has limitations in treatment.

In addition, in the case of coagulants, which are generally applied according to the strengthened total phosphorus (TP) concentration regulation, a large amount of Al ions flow into the water system, raising concerns about causing another type of environmental problem.

On the other hand, the reuse of sewage treatment water has a relatively simple treatment method and can reduce the pollutant load discharged into public waters, but there are also concerns about the occurrence of inorganic substances such as non-degradable organic matter or heavy metals or psychological reluctance to reused water.

In general, when reprocessing sewage treatment water for reuse, reprocessing is performed by applying various processes such as physicochemical treatment, biological treatment, or combined treatment that combines them according to the target water quality required by the consumer. Concentrated water containing high concentrations of salt, nitrogen, ionic materials, etc. is inevitably generated.

Such concentrated water is returned to the front end of the sewage treatment plant for reprocessing. However, when high-concentration concentrated water is treated in conjunction with the sewage treatment plant, it acts as an additional load in sewage treatment, causing many problems in stable biological sewage treatment, especially high salinity. Concentration causes protoplast separation in microorganisms, causing intracellular function degradation and leading to cell destruction, and eventually, there is a problem of directly adversely affecting effluent water quality by increasing SVI (sludge volume index) and floc disintegration.

Despite these problems, research results on the effect of concentrated water on biological sewage and wastewater treatment systems are insufficient, and it is reported that there are difficulties in selecting alternatives for appropriate treatment or process design. Development of technology to solve these problems This is an urgent need.

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

As such, according to the prior art, a process of increasing the denitrification efficiency of the anoxic tank by returning the CDI concentrated water enriched with nitrate nitrogen (NO3-) and TDS formed in the capacitive desalination tank to the anoxic tank is proposed, but the nitrification rate due to the decrease in water temperature during the winter season If the CDI concentration is lowered, not only nitrate nitrogen but also ammonia nitrogen are included in a considerable amount, so even if it is returned to the anoxic tank, it is unreasonable to expect the effect of improving the denitrification efficiency by the anoxic tank. It is a widely known fact that even if denitrification occurs, when a high concentration of TDS components (Ca2+, Mg2+, Cl-, etc.) contained in the concentrated water flows into the bioreactor, it adversely affects the activity of the bioreactor. For this reason, it is necessary to stably maintain the efficiency of the bioreactor by reducing the TDS concentration of the CDI-concentrated water returned to the bioreactor.

Therefore, an object of the present invention is to fusion the aerobic-centered biological process and the electrosorption process, thereby eliminating the need for various facilities required for the individual operation of the existing anaerobic / aerobic reaction and nitrification reaction, the capacity and site of the reaction tank and additional processes In particular, high-concentration concentrated water generated by repetition of the electrosorption process and surplus sludge, which is periodically drawn out to maintain a constant concentration of sludge during bioprocessing, are reacted together in an ion fixation tank to obtain high-concentration microorganisms. It is intended to provide a high-concentration concentrated water treatment system using ion fixation that can facilitate the treatment of high-concentration concentrated water generated in an electrosorption process by finally disposing of it as sludge after inducing bio-sorption.

As a means for achieving the above object, the high-concentration concentrated water treatment system using ion fixation of the present invention (hereinafter referred to as 'concentrated water treatment system of the present invention') biologically treats the inflow and wastewater to remove organic matter In a system including a reaction tank and a CDI treatment tank in which treated water treated in the bioreactor enters and adsorbs and treats ionic inorganic contaminants contained in the treated water, excess sludge discharged from the bioreactor and in the CDI treatment tank It is characterized by further comprising an ion fixation tank into which discharged CDI concentrated water is introduced, and ionic inorganic contaminants in the CDI concentrated water are adsorbed with excess sludge.

As an example, it is interposed between the CDI treatment tank and the ion fixation tank, the CDI concentrated water discharged from the CDI treatment tank flows in, and the ED concentrated water treated with the electrodialysis method It is characterized by further comprising a; ED treatment tank for discharging and allowing the discharged ED concentrated water to flow into the ion fixation tank.

As an example, the CDI treatment tank and the ED treatment tank are interconnected through a circulation line, and the ED concentrated water discharged from the ED treatment tank is ED re-concentrated water that has undergone a circulation process between the CDI treatment tank and the ED treatment tank And, it is characterized in that the discharged ED re-concentration water flows into the ion fixation tank.

As an example, the ion fixation tank is characterized in that excess sludge precipitated through the precipitation process is separated and discharged, and supernatant water is returned to the bioreactor.

As an example, supernatant water discharged through the precipitation process of the ion fixation tank is installed at the rear end of the ion fixation tank, and Struvite (NH4MgPO4 6H2O) reacts with ionic inorganic contaminants in the inflow supernatant. It is characterized by further comprising a Struvite generating tank for inducing crystallization and discharging treated water having a reduced concentration of ionic materials therethrough, and returning the discharged treated water to the bioreactor.

As an example, the ion fixation tank is characterized in that an adsorption accelerator containing at least one of a coagulant, a cationic component, and an anionic component is added to promote an adsorption reaction by the surplus sludge.

As such, the concentrated water treatment system of the present invention combines the biological process and the electrosorption (CDI) process to stably treat nitrogen and phosphorus without being affected by the water temperature in winter, and through the operation of the aerobic-centered bioprocess reactor, the capacity and The site and additional processes can be minimized, and there is an advantage in that maintenance costs can be reduced because facilities such as liquid transfer pumps and air supply devices required for existing anaerobic/aerobic reactions and nitrification reactions are not required.

In particular, high-concentration ion-concentrated water generated by repetition of the electro-adsorption process and surplus sludge discharged during the biological process are stored together in the ion fixation tank to induce a bio-sorption reaction by high-concentration microorganisms and finally be disposed of as sludge. There is an advantage in that the reduction of ionic substances in concentrated water and its treatment can be facilitated, and as a result, sewage treatment water can be efficiently reused.

1 is a schematic view showing the configuration of a concentrated water treatment system according to an embodiment of the present invention.
Fig. 2 is a schematic view showing an example in which an ED treatment tank is interposed in Fig. 1;
3 and 4 are schematic diagrams showing an example of the configuration of a struvite generating tank according to an 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 this 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. should be interpreted as a meaning and concept that corresponds to the technical idea of

Referring to FIG. 1, the concentrated water treatment system of the present invention basically includes a bioreactor 10 and a CDI treatment tank 20.

The bioreactor 10 removes organic matter from the inflowed wastewater and allows surplus sludge including organic matter generated in the treatment process to be discharged.

Excess sludge discharged from the bioreactor 10 may be intermittently or continuously transferred to the ion fixation tank 30 described below through a sludge transfer line, and the CDI treatment tank flowing into the ion fixation tank 30 ( 20) reacts with CDI concentrated water to enable bioadsorption.

For example, the surplus sludge may be sludge that is periodically drawn out to maintain a constant concentration of sludge in the bioreactor 10 .

Such a bioreactor 10 creates an environment capable of inducing a biological reaction from sewage and wastewater to separate and remove organic matter, and can be implemented in various ways through known technologies.

For example, the bioreactor 10 may be an aerobic reactor that removes organic components from inflow sewage by microbial metabolism through an aerobic process.

Such an aerobic reaction tank utilizes activated sludge to transfer treated water from which organic components are removed from inflow sewage to the CDI treatment tank 20 described below, and in the CDI treatment tank 20, organic components are present in the treated water from which they are removed. ionic ammonia nitrogen and partially nitrated nitrate nitrogen components and phosphorus in the form of PO ₄ -P can be removed through electrosorption.

At this time, the aerobic reaction tank may be provided with a membrane having a separation membrane structure although not shown in the drawing for more efficient removal of particulate organic matter.

The CDI treatment tank 20 is connected to the bioreactor 10, the treated water treated in the bioreactor 10 flows in, and the ionic inorganic contaminants contained in the introduced treated water are adsorbed and treated.

That is, the CDI treatment tank 20 is a desalination treatment tank that removes TDS (Total Dissolved Solid) and ionic inorganic pollutants present in influent water by an electroadsorption method using an electric field principle.

Although not shown in the drawings, the CDI treatment tank 20 may include one or more CDI modules in which a plurality of positive electrodes and negative electrodes are stacked at regular intervals, and a power supply module supplying power to the CDI module.

In addition, the CDI treatment tank 20 adsorbs and discharges ionic contaminants present in the influent flowing between the positive electrode and the negative electrode (treated water of the bioreactor 10) and then adsorbs them to the positive and negative electrodes. The regeneration process of desorbing the desorbed ionic contaminants may be repeated at least twice, and in this process, CDI concentrated water in which ionic contaminants are concentrated may be selectively discharged.

As such, in the present invention, through the bioprocess fusion electrosorption (CDI) process, it is possible to treat nitrogen components and phosphorus stably without being affected by water temperature in winter, and through the operation of the aerobic-centered bioreactor 10, the reactor capacity and site are reduced, It is possible to expect the effect of reducing equipment and maintenance costs through pump facilities for liquid transfer between anaerobic/aerobic reaction tanks and reduction of air consumption for the existing nitrification process.

However, in the CDI treatment tank 20 in which electroadsorption is performed, adsorption and desorption of ionic contaminants are repeated several times to generate high-concentration ion-concentrated water, which is necessarily treated.

Accordingly, in the present invention, by reacting the high-concentration ion-concentrated water generated in the CDI treatment tank 20 with the surplus sludge discharged to keep the microbial concentration in the bioreactor 10 constant, the high concentration of microorganisms in the surplus sludge It is characterized in that it further comprises an ion fixation tank 30 to be disposed of as sludge after bio-sorption is induced.

Specifically, the ion fixation tank 30 allows the surplus sludge discharged from the bioreactor 10 and the CDI concentrated water discharged from the CDI treatment tank 20 to flow in and react with them.

And the ion fixation tank 30 reduces the ion concentration of the stored CDI-concentrated water by inducing a reaction so that the ionic inorganic contaminants of the CDI-concentrated water are adsorbed on the surface or inside of the organic or inorganic matter contained in the excess sludge. Excess sludge adsorbed with ionic components is precipitated in the storage tank so that it can be separated and discharged later through a sludge transfer vehicle.

In organic matter separated through biological treatment, it has been studied that the extracorporeal polymers of microorganisms have specific ionic properties and have adsorption performance to adsorb ionic substances, NH ₄ ⁺ -N, NO3 ^-N , PO ₄ ^3- The CDI concentrated water containing ionic nutrients such as -P can be bioadsorbed on the surface of the organic matter of the excess sludge during the storage process in the ion fixation tank 30.

At this time, the operating conditions of the ion fixation tank 30, for example, the flow rate and timing of the inflow of surplus sludge and CDI concentrated water drawn from the bioreactor 10, pH conditions, addition of a coagulant to increase the ion fixation efficiency It is desirable to selectively set medicines according to the results of the removal characteristics of ionic nutrients accumulated in the past so that optimal bioadsorption performance can be derived.

In addition, the ion fixation tank 30 separates and discharges the excess sludge precipitated through the precipitation process and returns the supernatant of the ion fixation tank 30 to the bioreactor 10, so that the bioreactor 10 to reduce the driving load.

Here, the ion fixation tank 30 is not shown in the drawings, but a plurality of treatment tanks such as a conditioning tank, a reaction tank, and a precipitation tank may be provided to increase the efficiency of the bioadsorption reaction, and these plurality of treatment tanks may be operated separately is natural

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

Meanwhile, as shown in FIG. 2, the concentrated water treatment system of the present invention is interposed between the CDI treatment tank 20 and the ion fixation tank 30, and the CDI concentrated water discharged from the CDI treatment tank 20 flows in. , and further includes an ED treatment tank 40 that discharges ED concentrated water obtained by treating the inflowed CDI concentrated water by electrodialysis, and allows the discharged ED concentrated water to flow into the ion fixation tank 30. .

That is, in the concentrated water treatment system of the present invention, the ED treatment tank 40 is provided so that the ED concentrated water, in which the ion concentration of the CDI concentrated water is further concentrated, flows into the ion fixation tank 30, resulting in the inflow of the concentrated water By reducing the amount, the volume of the ion fixation tank 30, that is, the unit area of the ion fixation tank 30 can be minimized.

Specifically, the ED treatment tank 40 recovers the CDI concentrated water discharged during the regeneration process of regenerating the electrode by desorbing ions from the CDI treatment tank 20, and recovers the CDI recovered through an electrodialysis method Ions are separated from concentrated water, and ED treated water in which ions are separated and ED concentrated water in which ionic inorganic contaminants are more concentrated in this process are separated and discharged.

At this time, the ED treatment tank 40 supplies the ED treatment water from which ions are separated to the CDI treatment tank 20 so that it can be used as regeneration water in the process of regenerating the CDI module, or as shown in FIG. Similarly, it can be discharged by being joined to the treated water treated from the CDI treatment tank 20.

Although not shown in the drawing, the ED treatment tank 40 includes at least one dilution chamber in which concentrated CDI water flows in and ions are removed from the concentrated CDI water, and one or more enrichment chambers in which ions are separated and collected, and ED treatment in the dilution chamber Water and 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 ion fixation tank 30 .

In particular, the CDI treatment tank 20 and the ED treatment tank 40 are interconnected through a circulation line so that they undergo circulation and desalination treatment at least twice or more, and ED concentration flowing into the ion fixation tank 30 In the case of water, through a repetitive circulation process between the CDI treatment tank 20 and the ED treatment tank 40, the ED re-concentrated water is discharged as ED re-concentrated water having a more concentrated ion concentration, and this ED re-concentrated water into (30).

That is, the ED re-concentrated water discharged from the ED treatment tank 40 is re-concentrated to 50 to 90% according to the concentration of the CDI-concentrated water flowing into the ED treatment tank 40, and the CDI generated in the CDI treatment tank 20 Compared to the concentrated water, the volume of the concentrated water finally introduced into the ion-fixed tank 30 is introduced into the ion-fixed tank 30 in a state where the volume is further reduced.

As such, in the present invention, the volume and inflow of the concentrated water flowing into the ion fixation tank 30 are minimized, so that the volume of the ion fixation tank 30 can be minimized as well, and the ion fixation tank due to the more concentrated concentrated water. The bioadsorption reaction of (30) can be more active and accelerated, and in particular, the density change of the excess sludge contained in the ion fixation tank (30) can be minimized.

On the other hand, the concentrated water treatment system of the present invention is installed at the rear end of the ion fixation tank 30, as shown in FIGS. 3 and 4, and the supernatant discharged through the precipitation process of the ion fixation tank 30 flows in, In response to ionic inorganic contaminants in the inflow supernatant, crystallization of struvite (NH4MgPO4 6H2O) is induced, and through this, treated water having a reduced concentration of ionic substances is discharged, and the discharged treated water is the bioreactor ( 10) may further include a struvite generating tank 50 to be conveyed.

4 shows an example in which the struvite generating tank 50 is configured in a state in which the ED treatment tank 40 is provided, but the present invention is not limited thereto, and as shown in FIG. 3, the presence or absence of the ED treatment tank 40 and Regardless, it may be installed at the rear end of the ion fixation tank 30.

In general, in treating wastewater, nitrogen or phosphorus components cause serious eutrophication inside the water, and especially ammonia causes dissolved oxygen depletion, so the recovery of nitrogen and phosphorus is a major issue in water treatment. In the present invention, Through the struvite generating tank 50, residual nitrogen and phosphorus components that may be included in the supernatant can be recovered, as well as recovered nitrogen and phosphorus components can be recycled, thereby contributing to resource conservation and environmental protection.

The struvite generating tank 50 reacts with residual phosphorus and nitrogenous ions that may be included in the supernatant to generate struvite, separates and discharges it, and operates to create a crystallization environment that is a major factor in the crystallization of struvite do.

The reaction formula for the generation of the struvite is as follows.

Mg ²⁺ + NH ₄ ⁺ + PO ₄ ^3- + 6H ₂ O → MgNH ₄ PO ₄ 6H ₂ O

That is, in the struvite generating tank 50, the main composition (NH ₄ ⁺ , PO ₄ ^3- , 6H ₂ O) for struvite generation can be obtained from the supernatant, and as a result of preliminary investigation of the components of the supernatant, According to the addition of magnesium (Mg ²⁺ ), etc. in an appropriate molar ratio, the above reaction formula for the generation of struvite can be satisfied.

Here, as the method of crystallizing struvite by the struvite generating tank 50 and the operating conditions, a suitable one can be selected and applied among various methods known in the art.

However, there is a research result that the crystallization of struvite proceeds rapidly under weak alkali conditions of pH 8 to 10. In addition to the composition for the above reaction formula, an alkali agent such as sodium hydroxide can be selectively added in the crystallization of struvite. is natural

As described above, the treated water in which specific ionic inorganic contaminants are removed and separated by crystallization of struvite is returned from the struvite generating tank 50 to the bioreactor 10 as described above.

As such, in the concentrated water treatment system of the present invention, residual phosphorus and nitrogenous ions that can be returned as supernatant can be recovered through the struvite generating tank 50 without using various biological and physicochemical methods, thereby reducing treatment costs. It is possible to save, and the crystallized struvite can be separately reused as an applicable resource such as fertilizer.

Through the above description, those skilled in the art will know that various changes and modifications are possible without departing from the technical idea of the present invention. Therefore, the technical scope of the present invention is not limited to the contents described in the detailed description of the specification, but should be defined by the claims.

10: bioreactor 20: CDI treatment tank
30: ion fixation tank 40: ED treatment tank
50: Struvite generating tank

Claims (6)

A system comprising a bioreactor for biologically treating the inflowed wastewater to remove organic matter and a CDI treatment tank for adsorbing and treating ionic inorganic contaminants contained in the treated water into the bioreactor. ,
It is installed at the rear end of the CDI treatment tank, recovers the CDI concentrated water discharged during the regeneration process of regenerating the electrode by desorbing ions from the CDI treatment tank, and collects ions from the CDI concentrated water recovered through the electrodialysis method. an ED treatment tank for separating and discharging ED-treated water in which ions are separated and ED-concentrated water in which ionic inorganic contaminants are relatively more concentrated than the CDI-concentrated water in this process;
Excess sludge discharged from the bioreactor and ED concentrate discharged from the ED treatment tank are respectively introduced, and ionic inorganic contaminants in the ED concentrate are adsorbed with the excess sludge, and the adsorption reaction is followed by a precipitation process An ion fixation tank in which excess sludge and supernatant precipitated through the separation and discharge; and
Installed at the rear end of the ion fixation tank, the supernatant separated and discharged through the precipitation process of the ion fixation tank flows in, and magnesium (Mg2+) is added and the pH is set to 8 to 10 to remove ionic inorganic contaminants from the introduced supernatant. Struvite generator induces crystallization of Struvite (NH4MgPO4 6H2O), recovers crystallized resources, separates and discharges treated water with reduced concentration of ionic substances, and returns the discharged treated water to the bioreactor ; Including more,
The CDI treatment tank and the ED treatment tank are connected to each other through a circulation line, and the ED concentrated water discharged from the ED treatment tank is repeatedly circulated between the CDI treatment tank and the ED treatment tank a plurality of times and subjected to desalination treatment to re-concentrate ED. High concentration concentrated water treatment system using ion fixation, characterized in that the discharged ED re-concentrated water flows into the ion fixation tank and the volume and inflow of the inflow concentrated water are minimized to minimize the volume of the ion fixation tank.
delete delete delete delete According to claim 1,
The ion fixation tank,
A highly concentrated concentrated water treatment system using ion fixation, characterized in that an adsorption accelerator containing at least one of a coagulant, a cationic component, and an anionic component is added to promote the adsorption reaction by the surplus sludge.

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