KR101267541B1 - Bio-electrochemical wastewater treating apparatus for a simultaneous removal of organic nitrogen and organic matter and wastewater treatment method using the apparatus - Google Patents

Abstract

PURPOSE: A bioelectrochemical wastewater treating apparatus is provided to improve velocity of moving ammonia and to enable excessive nitrate in aerobic zone to move to a denitrification zone. CONSTITUTION: A bioelectrochemical wastewater treating apparatus comprises an anaerobic tank receiving waste water; an aerobic tank connected to the anaerobic tank; a cation exchange membrane; an anion exchange membrane; and a water transfer pipe. The cation exchange membrane connects the anaerobic tank and aerobic tank to each other. The anion exchange membrane connects the aerobic tank and a denitrification tank. The anaerobic tank decomposes organic material in the waste water by using a reduction electrode and microorganism. The aerobic tank forms nitrate from ammonia which flows from the anaerobic tank through the cation exchange film, by using an oxidation electrode and microorganism. [Reference numerals] (AA) Inflow water transfer pipe; (BB) Power source; (CC) Cation exchange film; (DD) Anion exchange film; (EE) Anaerobic tank; (FF) Reduction electrode; (GG) Aerobic tank; (HH) Denitrification tank; (II) Oxidation electrode; (JJ) Inflow water; (KK) Air diffuser; (LL) Aeration

Description

Bio-electrochemical wastewater treating apparatus for a simultaneous removal of organic nitrogen and organic matter and wastewater treatment method using the apparatus}

The present invention relates to a bioelectrochemical wastewater treatment apparatus for simultaneous removal of organic nitrogen and organic matter and a wastewater treatment method using the same.

High concentration organic wastewater, such as dairy waste and livestock waste, contains high concentrations of organic matter and nitrogen, so it is generally treated through anaerobic digestion tanks to remove residual organic matter and induce nitrification and induce denitrification through return.

However, since it is not possible to completely remove organic matter through anaerobic digestion, the aeration tank is generally installed at the rear end of the anaerobic digestion tank to aeration or an oxidation process is installed to remove residual organic matter.

In the case of nitrogen removal, the residence time in the aerobic tank also becomes longer because nitrification may be induced after the organic matter is removed. In addition, after the nitrification process, the denitrification tank may be denitrated through an internal transport or an external carbon source may be denitrified to install an additional denitrification tank, and then an aerobic tank must be installed again.

Therefore, the disadvantage of the existing technology is that the removal of organic matter is required, long residence time is required, and the whole process is complicated.

In Korea, most of the sewage treatment and livestock wastewater treatment is carried out using activated sludge method. Activated sludge treatment can remove most suspended solids and organic matter, but the removal efficiency of nutrients such as nitrogen and phosphorus is only 20-40%.

Processes for treating nutrients such as nitrogen and phosphorus include physical, chemical and biological treatments.

The physicochemical treatment methods include ammonia degassing, ion exchange using selective adsorption, precipitation of phosphorus using slaked lime and flocculant, and precipitation of struvite formation that simultaneously precipitates nitrogen and phosphorus. It is used.

However, the above physicochemical methods have disadvantages such as being sensitive to temperature and costly, and are difficult to operate due to the limited chemical cost and operation environment, and are unstable in effluent water, Reluctant to use.

In the biological treatment method, in the case of nitrogen, nitrification (eg, ammonia is transformed into nitrate form) by nitrifying bacteria (for example, Nitrosomonas and Nitrobacter) under aerobic conditions in ammonia nitrogen and organic nitrogen in the dissolved state, and denitrification Oxidized bacteria (eg, Pseudomonas, Paracoccus denitrifiers) are used as electron acceptors instead of oxygen under anoxic conditions, converted to nitrogen gas and released into the atmosphere (denitrification) and removed.

As a method for overcoming the wastewater treatment problem as described above may include the DEPHANOX process developed in Italy. In this process, anaerobic contacting tanks and separation tanks are used to adsorb organic matter in the anaerobic contacting tank, induce the release of phosphorus, separate organic matter and microorganisms adsorbed in the separation tank and enter the subsequent denitrification tank, Nitrogen compounds are nitrified in separate reactors and sent to subsequent denitrification tanks for denitrification by microorganisms that adsorb organic matter.

That is, the DEPHANOX process is a process in which denitrification and nitrification are carried out in separate sludges and reactors, and the phosphorus is excessively ingested by microorganisms in a subsequent aerobic reactor.

However, despite these advantages of the DEPHANOX process, the organic nitrogen and ammonia nitrogen flowing into the denitrification tank from the separation tank during the subsequent treatment in the nitrification tank are not sufficiently decomposed or nitrified, but are discharged and are only in a single denitrification reactor subsequent to the nitrification tank. Because denitrification is made, there is a disadvantage that high nitrogen removal efficiency cannot be expected.

In order to solve this problem, CESON (cation exchange simultaneous organics and nitrogen removal) process was developed as a prior art denitrification process using cation exchange and biological reaction.

However, in the CESON process, ammonia is moved by the cation exchange membrane without an external potential, and nitrate migration from the aerobic tank to the anaerobic tank is limited, so that when the load of ammonia increases, nitrate accumulates inside the aerobic tank.

In order to solve this problem, the inventors also developed a modified-ion exchange biological reactor (M-IEBR) process consisting of an anaerobic tank, an aerobic tank, and a denitrification tank.

The M-IEBR process adds an anion exchanger to the CESON process, separates the nitrates produced by the oxidation of ammonia in the aerobic tank, supplies them to the denitrification tank, solves the nitrate accumulation problem in the aerobic tank, and improves the processing capacity by introducing external potentials. Could get the result.

However, because of the use of two cathodes and two external power sources in the aerobic tank, it was economically limited to be used in actual sewage treatment facilities.

Livestock wastewater contains more than 1,500 mg N / L of ammonia, and organic matter contains more than 10,000 mg / L of COD _Cr . In the M-IEBR process, it is important to supply a large amount of nitrates economically, stably and at an improved rate because it induces biological denitrification as a reaction for removing organic matter. There is a disadvantage in that the operation cost of a lot.

Patent Literature 1 discloses a biological denitrification method and apparatus for wastewater using reduction power of electrical energy to remove nutrients such as organic matter and nitrogen from wastewater using electrical energy as reducing power.

Patent Literature 2 discloses a nitrogen-containing wastewater treatment system using an ion exchange membrane. Specifically, an ion exchange membrane is installed inside the electrolysis device that passes only electrons but does not pass water so that the oxidation reaction occurs while the electrolyte is added to the + pole, while the reduction reaction is continued while the waste water is added to the pole. The nitrogen gas and hydrogen gas are removed directly from the pole.

Patent Document 3 discloses a method for simultaneously removing high concentrations of organic substances, nitrogen and phosphorus and reducing sludge generated during livestock wastewater treatment using adherent biofilms.

Patent Document 4 discloses an anaerobic tank and a wastewater treatment method including the nitrification tank connected by a cation exchange membrane.

Patent Document 5 discloses a hybrid type sewage treatment system and a method for treating wastewater using the same.

Therefore, the present inventors are studying the method of improving the wastewater treatment capacity and speed by moving the ammonia from the anaerobic tank to the aerobic tank through ion exchange more economically and efficiently and improving the rate of nitrate denitrification and denitrification tank. By installing a reduction electrode in the anaerobic tank and an anode in the aerobic tank in the reaction tank consisting of an aerobic tank and a denitrification tank, an electric field is formed to improve the moving speed of ammonia, which is directly related to the denitrification reaction, and the nitrate for the denitrification reaction is added to the aerobic tank. If present in excess of the present invention to move to a denitrification tank to oxidize the organic matter and to help the denitrification reaction wastewater treatment method to significantly improve the capacity and speed of wastewater treatment and completed the present invention.

Patent Document 1: Patent Application KR 10-1999-0018704 Patent Document 2: Patent Application KR 10-2002-0001792 Patent Document 3: Patent Application KR 10-2002-0023856 Patent Document 4: Patent Application KR 10-2009-0009570 Patent Document 5: Patent Application KR 10-2008-0029907

It is an object of the present invention to provide a bioelectrochemical wastewater treatment apparatus capable of simultaneously removing organic matter and organic nitrogen contained in sewage water.

Another object of the present invention is to provide a bioelectrochemical wastewater treatment method capable of simultaneously removing organic matter and organic nitrogen contained in sewage water.

Still another object of the present invention is to provide a method for simultaneously removing organic matter and organic nitrogen in wastewater using the apparatus.

In order to achieve the above object, the present invention provides an anaerobic tank into which wastewater is introduced;

An aerobic tank communicating with the anaerobic tank;

A denitrification tank communicating with the expiratory tank;

A cation exchange membrane communicating the anaerobic tank and the aerobic tank;

An anion exchange membrane in communication with the aerobic tank and the denitrification tank;

A potential device comprising a reduction electrode provided in the anaerobic tank and an anode provided in the aerobic tank;

Provided is a bioelectrochemical wastewater treatment apparatus capable of simultaneously removing organic matter and organic nitrogen, including an influent feed pipe communicating the anaerobic tank and the denitrification tank.

In addition, the present invention comprises the step of introducing the wastewater containing organic matter and organic nitrogen into the anaerobic tank (step 1);

Supplying power to the potential device, decomposes the organic matter contained in the wastewater on the surface of the microbial layer formed on the cathode electrode provided in the anaerobic tank, induces denitrification of nitrate inside the microbial layer, and ammonia contained in the wastewater Moving to the aerobic tank through a cation exchange membrane communicating with the aerobic tank (step 2);

Supplying power to the potential device, decomposing organic matter on the surface of the microorganism layer formed on the microorganism suspended in the aerobic tank or the anode electrode provided in the aerobic tank, and generating ammonia, which has moved to the aerobic tank, in step 2 as nitrate (step 3) ;

Supplying power to the power supply device to denitrate the nitrate produced in step 3 in the microbial layer formed on the anode provided in the aerobic tank (step 4); And

In the step 4, the remaining nitrate, which cannot be denitrated, is transferred to the denitrification tank through an anion exchange membrane communicating the aerobic tank and the denitrification tank by the concentration gradient, and the nitrate is organic matter in the wastewater introduced through the influent feed pipe communicating the anaerobic tank and the denitrification tank. The present invention provides a wastewater treatment method capable of simultaneously removing an organic material and organic nitrogen, which comprises reacting with oxidized organic material and performing a denitrification reaction (step 5).

Furthermore, the present invention provides a method for simultaneously removing organic matter and organic nitrogen in wastewater using the apparatus,

Introducing wastewater into the anaerobic tank (step 1); And

Provided is a method for simultaneously removing organic matter and organic nitrogen from wastewater comprising the step of supplying power to a potential device.

In the wastewater treatment method according to the present invention, in the process of simultaneously removing organic matter and organic nitrogen through a bioelectrochemical reaction, a reduction electrode is installed in an anaerobic tank and an anode is installed in an aerobic tank in an anaerobic tank-aerobic tank-denitrification tank. In addition to improving the transport speed of ammonia, which is directly related to the denitrification reaction, if excessive nitrate is present in the aerobic tank, it moves to the denitrification tank to oxidize organic matter and helps the denitrification reaction to improve the wastewater treatment capacity and speed. Significantly improved, it can be usefully used in wastewater treatment apparatus or method for water quality improvement.

1 is a schematic view of the M-IEBR2 wastewater treatment apparatus according to an embodiment of the present invention.
Figure 2 is a graph showing the effect of removing the total nitrogen in the livestock wastewater M-IEBR2 process according to the present invention.
3 is a graph showing the effect of removing ammonia in the livestock wastewater by the M-IEBR2 process according to the present invention.
Figure 4 is a graph showing the effect of removing the organic matter in the livestock wastewater by the M-IEBR2 process according to the present invention.

Prior to describing the invention in detail, a brief comparison with the prior art is made and the term 'M-IEBR2 process' is defined. The present invention is named M-IEBR2 (modified-ion exchange biological reactor 2) process with a complex mechanism of electrochemical ion exchange, nitrification in aerobic tank and biological denitrification reaction.

The ultimate object of the present invention is to improve the wastewater treatment efficiency of the prior art modified-ion exchange biological reactor (M-IEBR) process.

In the improvement of the prior art M-IEBR process and the apparatus of the M-IEBR2 process according to the present invention, the M-IEBR process apparatus is the first oxidation electrode installed in the anaerobic tank and the two reduction electrodes of the aerobic tank and the second oxidation of the denitrification tank On the other hand, the M-IEBR2 process apparatus according to the present invention is composed of one power source by installing one reducing electrode in an anaerobic tank and one anode in an aerobic tank. This is a significant reduction in consumption.

In the M-IEBR process of the prior art, the concentration gradient of ions between the two reactors between the ion exchange membranes acted as the main electromotive force in the transfer of ammonia and nitrates by the electric field induced by the two anode and the cathode.

In the M-IEBR2 process according to the present invention, by installing one cathode and one anode in each of the anaerobic tank and the aerobic tank, an electric field is applied to facilitate the movement of ions, and also to assist the decomposition of organic matter in the cathode. Degradation of hardly degradable organics contained in livestock wastewater can also be expected.

Hereinafter, the present invention will be described in detail.

The present invention provides a bioelectrochemical wastewater treatment apparatus capable of simultaneous removal of organic matter and organic nitrogen comprising the following configuration:

An anaerobic tank into which wastewater is introduced;

An aerobic tank communicating with the anaerobic tank;

A denitrification tank communicating with the expiratory tank;

A cation exchange membrane communicating the anaerobic tank and the aerobic tank;

An anion exchange membrane in communication with the aerobic tank and the denitrification tank;

A potential device comprising a reduction electrode provided in the anaerobic tank and an anode provided in the aerobic tank;

Influent feed pipe communicating the anaerobic tank and the denitrification tank.

Hereinafter, the wastewater treatment apparatus according to the present invention will be described in detail with reference to FIG. 1.

1, the wastewater treatment apparatus according to an embodiment of the present invention has a structure in which the anaerobic tank and the denitrification tank are connected to the anaerobic tank through the communication unit in the order of anaerobic tank → aerobic tank → denitrification tank. The communication portion between the anaerobic tank and the aerobic tank is provided with a cation exchange membrane, and the communication portion between the aerobic tank and the denitrification tank is provided with an anion exchange membrane. In addition, the apparatus includes a potential device including a reduction electrode provided in the anaerobic tank and an anode provided in the aerobic tank, and an influent feed pipe communicating with the anaerobic tank and the denitrification tank.

In the wastewater treatment apparatus according to the invention, the inlet water supply is connected to the lower portion of the anaerobic tank. Wastewater containing organic matter and nitrogen is introduced through the inflow water supply unit, and a primary decomposition of the hardly decomposable organic matter contained in the wastewater occurs by introducing an existing anaerobic fermentation reaction. In addition, the upper part of the anaerobic tank is provided with an influent feed pipe that can be transferred to the lower part of the denitrification tank mainly containing the organic material that did not pass through the cation exchange membrane described below.

Specifically, in the anaerobic tank, when wastewater containing a high concentration of organic matter is introduced, organic matter is decomposed through hydrolysis, organic acid generation, methane fermentation, and the like. In addition, the organic matter contained in the wastewater is reduced by using the microorganisms floating on the surface of the microbial layer formed on the cathode and the cathode, and the nitrates contained in the wastewater are located inside the microbial layer formed on the cathode. Diffused into microorganisms, denitrified and released as nitrogen gas.

The reaction that can occur in the anaerobic reduction electrode is as follows.

<Reaction Scheme 1>

^{_{8H 2 O + 8e - → 4H}} 2 + 8OH - E '= -420 mV

<Reaction Scheme 2>

_{^{2NO 3 - + 10e - + 12H}} + → N 2 + 6H 2 O

The bioelectrochemical decomposition process of the organic material as described above depends on the type of microorganism, but in general, when a cathode is installed, hydrogen gas generation and nitrate denitrification are possible as shown in Schemes 1 and 2.

Therefore, according to the external potential, stable denitrification can be achieved even if the ammonia transferred from the anaerobic tank to the aerobic tank is converted from the aerobic tank to the nitrate, even if a high concentration of nitrate moves through the cation exchange membrane to the anaerobic tank by the concentration gradient. .

In addition, in the case of high salinity wastewater, such as livestock wastewater, the ionic component is reduced or a cation and anion are combined by a reduction electrode installed in the anaerobic tank to reduce the salinity in the wastewater.

In the wastewater treatment apparatus according to the present invention, the cation exchange membrane serves to selectively pass ammonia generated from or contained in the wastewater containing organic matter introduced into the anaerobic tank to an aerobic tank. The cation exchange membrane used in the embodiment of the present invention is a cation exchange membrane having a selectivity to monovalent cations, and CMX was used in NEOSRPTA membrane of Astom, Japan, and there is no particular limitation in the selection of the ion exchange membrane.

In the wastewater treatment apparatus according to the present invention, the aerobic tank converts ammonia introduced through the cation exchange membrane into nitrate using microorganisms suspended in the aerobic tank and microorganisms located on the surface of the microbial layer formed on the anode. Nitrate is diffused to the microorganisms located inside the microbial layer formed on the anode and discharged to nitrogen gas through the denitrification reaction.

Specifically, the ammonia selectively introduced through the cation exchange membrane through the microorganisms suspended in the aerobic tank and the microorganisms located on the surface of the microbial layer formed on the anode electrode induces nitrification through a reaction as shown in the following reaction schemes 3 to 7 It serves to produce nitrate for the next process.

<Reaction Scheme 3>

^{_{NH 4 + + 1.5O 2 ---->}} NO 2 - + H 2 O + 2H + (Nitrosomonas)

<Reaction Scheme 4>

^{_{NO 2 - + 0.5O 2 ---->}} NO 3 - (Nitrobacter)

Scheme 5

_{^{NH 4 + + NO 2 - ----}} > N 2 + 2H 2 O (Anammox bacteria)

<Reaction Scheme 6>

^{_{NH 4 + + 2H 2 O +}} 6Fe 3 + ---> NO 2 - + 6Fe 2 + + 8H + (Iron reducing bacteria)

<Reaction Scheme 7>

_{^{NO 2 - + 2Fe 3 + +}} H 2 O ---> NO 3 - + 2Fe 2 + + 2H + (Iron reducing bacteria)

The reaction of Scheme 3-7 is carried out through various nitric acid producing bacteria present in the aerobic tank.

Schemes 3 and 4 are reactions that occur when the dissolved oxygen (DO) concentration is sufficiently maintained in the nitrification reaction. That is, when no organic matter is present and the concentration of ammonia is low, the dissolved oxygen amount deficiency does not occur and oxidation of ammonia occurs smoothly.

Scheme 5-7 is an oxidation reaction of ammonia that occurs when oxygen supply is not smooth. When wastewater such as livestock wastewater flows in, the concentration of ammonia reaches thousands of ppm, so that oxygen is not supplied smoothly, so the 5-7 reactions may occur.

The reactions that can occur at the aerobic electrode are as follows.

<Reaction Scheme 8>

4Fe-> 4Fe ^{2 +} + 8e ^- E '= 700 mV

<Reaction Scheme 9>

4Fe ^{2 +} + 10H ₂ O + O _2- > 4Fe (OH) ₂ + 8H ⁺

On the other hand, some of the converted nitrate is reduced back to ammonia by oxidation of the zero valent iron of the anode. However, ammonia reduced by zero-valent iron is oxidized back to nitrate by microorganisms suspended in the aerobic tank and microorganisms located on the surface of the microbial layer formed on the anode, and the nitrate is formed inside the microbial layer formed on the anode. Diffusion to the microorganisms that are located is discharged to nitrogen gas through the process of denitrification.

Specifically, in the aerobic tank, after the ammonia selectively introduced through the cation exchange membrane in the anaerobic tank is converted to nitrate by the reaction schemes 3 and 4, some nitrates are again ammonia by the zero-valent iron of the anode installed in the aerobic tank according to Scheme 10 below. Is switched to.

<Reaction formula 10>

4Fe + NO ₃ ^- + 10H ⁺ -> 4Fe ^{2 +} + NH ₄ ⁺ + 10H ₂ O

In addition, the aerobic tank of the apparatus according to the present invention may further include an aeration provided with an acid pipe so that nitrification is performed smoothly. The aeration unit provided with the diffuser may be provided at the bottom of the aeration tank to provide oxygen supply and fluidity of the liquid. In addition, it may further include a propeller to further impart the fluidity of the liquid in the aerobic tank.

In the wastewater treatment apparatus according to the present invention, the potential device is provided with a reduction electrode in the anaerobic tank and the anode is provided in the aerobic tank, the ammonia of the anaerobic tank is passed through the cation exchange membrane to the aerobic tank by the electric field generated by applying a voltage. It improves the speed and assists the decomposition of organic matter in the anaerobic cathode of the electrode. At this time, by controlling the magnitude of the voltage applied to the potential device, it is possible to control the rate at which the ammonia is passed through the cation exchange membrane to the aerobic tank.

In the wastewater treatment apparatus according to the present invention, the anion exchange membrane serves to selectively pass the nitrate generated in the aerobic tank to the denitrification tank. As an anion exchange membrane used in one embodiment of the present invention as an anion exchange membrane having a selectivity to monovalent anions, AMX was used in NEOSRPTA membrane of Astom, Japan, and there is no particular limitation in the selection of the ion exchange membrane.

In the wastewater treatment apparatus according to the present invention, the denitrification tank is selectively transported through an anion exchange membrane by nitrate that is not denitrified in an aerobic tank, and the transferred nitrate is transported through an influent feed pipe communicating an anaerobic tank and a denitrification tank. Reacts with the organics in the incoming wastewater to assist the oxidation of the organics and denitrification to generate nitrogen.

Specifically, unlike the M-IEBR, since there is no second potential device in the denitrification tank, the denitrification reaction may be performed without the need for a separate power supply and an anode.

The denitrification reaction carried out in the denitrification tank is shown in Scheme 11 below.

<Reaction Scheme 11>

2NO ₃ ^- + 6H _{2 ^{----> N 2 + 2OH - +}} 4H 2 O

In the wastewater treatment apparatus according to the present invention, the potential device is provided with a reduction electrode in the anaerobic tank and the anode is provided in the aerobic tank, the ammonia of the anaerobic tank is passed through the cation exchange membrane to the aerobic tank by the electric field generated by applying a voltage. It improves the speed and assists the decomposition of organic matter in the anaerobic cathode of the electrode. At this time, by controlling the magnitude of the voltage applied to the potential device, it is possible to control the rate at which the ammonia is passed through the cation exchange membrane to the aerobic tank.

In addition, the present invention comprises the step of introducing the wastewater containing organic matter and organic nitrogen into the anaerobic tank (step 1);

Supplying power to the potential device, decomposes the organic matter contained in the wastewater on the surface of the microbial layer formed on the cathode electrode provided in the anaerobic tank, induces denitrification of nitrate inside the microbial layer, and ammonia contained in the wastewater Moving to the aerobic tank through a cation exchange membrane communicating with the aerobic tank (step 2);

Supplying power to the potential device, decomposing organic matter on the surface of the microorganism layer formed on the microorganism suspended in the aerobic tank or the anode electrode provided in the aerobic tank, and generating ammonia, which has moved to the aerobic tank, in step 2 as nitrate (step 3) ;

Supplying power to the power supply device to denitrate the nitrate produced in step 3 in the microbial layer formed on the anode provided in the aerobic tank (step 4); And

In the step 4, the remaining nitrate, which cannot be denitrated, is transferred to the denitrification tank through an anion exchange membrane communicating the aerobic tank and the denitrification tank by the concentration gradient, and the nitrate is organic matter in the wastewater introduced through the influent feed pipe communicating the anaerobic tank and the denitrification tank. The present invention provides a wastewater treatment method capable of simultaneously removing an organic material and organic nitrogen, which comprises reacting with oxidized organic material and performing a denitrification reaction (step 5).

Hereinafter, the wastewater treatment method according to the present invention will be described in more detail step by step.

In the wastewater treatment method according to the present invention, the step 1 is to introduce the wastewater containing organic matter and ammonia into the anaerobic tank, and introduce a conventional anaerobic fermentation reaction to induce the primary decomposition of the hardly decomposable organic matter contained in the wastewater. Step.

The ammonia load of the wastewater flowing into the anaerobic tank in step 1 is preferably 0.5 kg N / m 3 d or more. If the ammonia load is less than 0.5 kg N / m 3d, the organic matter and organic nitrogen can be removed by performing a simpler process using the M-IEBR process apparatus.

However, in the process using the M-IEBR process apparatus, since the nitrate accumulates in the aerobic tank when the ammonia load increases, there is a problem that the process cannot be operated efficiently. This is considered to be due to the fact that the removal rate of nitrate by diffusion is significantly lower than that of oxidation of ammonia and nitrate accumulates.

Accumulation of nitrates can potentially cause nitrification. Therefore, when the ammonia load is 0.05 kg N / m 3d or more, organic matter and organic matter using the wastewater treatment apparatus according to the present invention, which can remove nitrogen in the aerobic tank, in order to balance the production and removal of nitrate in the aerobic tank. It is desirable to remove nitrogen at the same time.

In the wastewater treatment method according to the present invention, step 2 supplies power to a potential device to decompose organic matter contained in the wastewater on the surface of the microbial layer formed on the cathode, and denitrification of nitrate inside the microbial layer. It is a step of inducing and transferring the ammonia contained in the wastewater to the aerobic tank through the cation exchange membrane.

At this time, the ammonia can be selectively introduced into the aerobic tank through the cation exchange membrane, the speed of the ammonia passes through the cation exchange membrane is increased as the magnitude of the voltage supplied to the potential device.

The ammonia introduced into the aerobic tank may be converted to nitrate through nitrification according to the above Reaction Formula 3-4.

In the wastewater treatment method according to the present invention, the step 3 is to supply power to the potential device, the oxidation of organic matter on the surface of the microorganism layer formed on the microorganism floating in the aerobic tank or the anode and the ammonia moved to the aerobic tank in the step 2 Is a step of producing nitrate.

On the other hand, some of the converted nitrate is reduced back to ammonia by oxidation of the zero valent iron of the anode. The amount of nitrates reduced to ammonia is determined by the amount of oxidized zero iron, and can be carried out through a reaction as in Scheme 10 described above.

However, ammonia reduced by zero-valent iron is oxidized back to nitrate by microorganisms suspended in an aerobic tank and microorganisms located on the surface of the microbial layer formed on the anode.

In the wastewater treatment method according to the present invention, step 4 is a step of supplying power to the power supply device, and denitrifying the nitrate produced in step 3 to discharge nitrogen gas inside the microbial layer formed on the anode.

In the wastewater treatment method according to the present invention, the step 5 is to move the nitrate remaining in the denitrification in step 4 to the denitrification tank through an anion exchange membrane by the concentration gradient, the nitrate in the influent feed pipe communicating the anaerobic tank and the denitrification tank The organic matter is oxidized by reacting with the organic matter in the wastewater introduced through the denitrification reaction.

At this time, the nitrate is selectively introduced into the denitrification tank through the anion exchange membrane by the concentration gradient, the greater the magnitude of the voltage supplied to the potential device, the faster the ammonia passes from the anaerobic tank through the cation exchange membrane to the aerobic tank to improve the As the concentration increases, the concentration of nitrate increases, which increases the rate at which the nitrate is transferred to the denitrification tank through the anion exchange membrane.

The denitrification of step 5 may be carried out through the same reaction as in Scheme 11 described above.

By the nitrogen removal reaction of the steps 2, 4 and 5 and the organic material removal reaction of the steps 2, 3 and 5 in the wastewater treatment method according to the present invention it is possible to remove nitrogen and organics at the same time.

M-IEBR2 process according to the present invention is a process that can remove the organic matter and nitrogen more economically and efficiently by changing the electrode arrangement and reducing the number of electrodes and power than the conventional M-IEBR process apparatus.

In the anaerobic tank, the rate of ammonia passing through the cation exchange membrane to the aerobic tank is increased, and some nitrates are denitrated in the aerobic tank, and nitrates, which are not denitrated in the aerobic tank, are transferred to the denitrification tank through the anion exchange membrane to assist the oxidation of organic matter and denitrification. Chemical reactions can be expected to improve wastewater treatment capacity and speed.

In the exhalation tank, an anode is present and finally receives electrons generated from the cathode provided in the anaerobic tank to serve to receive electrons required for the reduction of chemicals.

Some microorganisms, such as Shewanella sp., Are capable of delivering electrons directly to the electrode, while others can supply electrons to the electrode through redox reactions using chemicals. In addition, they can be utilized as an electromotive force for organic matter decomposition by using the potential difference between the anode and the cathode as an electromotive force when decomposing the organic matter. In Scheme 1 and Scheme 8, the potential difference between the anaerobic tank and the aerobic tank is 0.28V.

In addition, when the external potential is supplied, decomposition reactions of bioelectrochemical organics occur at the cathode and electrons generated at this time are used for hydrogen generation or denitrification. Therefore, in the cathode, the reduction reaction of nitrate may occur using the generated electrons. At this time, since the nitrate is present as dissolved ions, the nitrate can be easily reduced because of its excellent reactivity with the electrode.

Furthermore, the present invention provides a method for simultaneously removing organic matter and organic nitrogen in wastewater using the apparatus,

Introducing wastewater into the anaerobic tank (step 1); And

Provided is a method for simultaneously removing organic matter and organic nitrogen from wastewater comprising the step of supplying power to a potential device.

In summary, the reaction taking place in the M-IEBR2 process according to the present invention,

Anaerobic decomposition of organics in anaerobic tanks,

Transfer of ammonia through the cation exchange membrane,

Transfer of nitrates through anion exchange membrane,

Conversion of ammonia to nitrates in aerobic tanks,

Conversion of the anode back to ammonia with the reduction of nitrates by zero-electrode in the aerobic tank,

Conversion of ammonia to nitrate on the surface of the microorganisms suspended in the aerobic tank or on the microbial layer formed on the anode,

Nitrogen gas emission by the denitrification of nitrate inside the microbial layer formed on the anode,

In the denitrification tank, the nitrate reacts with the organics to oxidize the organics and denitrate the nitrates.

The overall control of the rate of this reaction is an externally supplied potential.

As described above, in the wastewater treatment method according to the present invention, in the process of simultaneously removing organic matter and organic nitrogen through a bioelectrochemical reaction, a reduction electrode is installed in an anaerobic tank in a reaction tank consisting of an anaerobic tank, an aerobic tank and a denitrification tank and oxidized in an aerobic tank. By installing an electrode to form an electric field, not only does the transfer rate of ammonia, which is directly related to the denitrification reaction, improve, but also when there is an excessive amount of nitrate in the aerobic tank, it moves to the denitrification tank to oxidize organic matter and help the denitrification reaction. Significantly improving the treatment capacity and speed, it can be usefully used in wastewater treatment apparatus or method for water quality improvement.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

Example 1 Simultaneous Removal of Ammonia and Organics

As shown in FIG. 1, a reactor was constructed (hereinafter referred to as M-IEBR2, modified-ion exchange biological reactor 2 process) to operate the process. As the cation exchange membrane between the anaerobic tank and the aerobic tank, CMX of ASTOM (Tokyo, Japan) was used, and the anion exchange membrane between the aerobic tank and the denitrification tank was used by AMX of the same company.

The influent contained 1,992 mg N / L of ammonia, 0.0 mg N / L of nitrate, 13,038 mg COD / L of organics and 0.0 mg N / L of nitrous nitrogen, pH 8.3, hydraulic retention time (HRT) of 5 days. The reactor had a capacity of 2.0 L and an operating temperature of 24-27 ° C. Aeration was carried out only in the aerobic tank and dissolved oxygen (DO) was maintained at 4-8 ppm. The material of the electrode mounted inside the anaerobic reactor was graphite, and the material of the electrode mounted inside the aerobic reactor was iron. 3000 mV potential was applied to the anaerobic tank and the aerobic tank using a power supply, where the electrode of the anaerobic tank was the reducing electrode and the electrode of the aerobic tank was used as the anode. Operation under these conditions led to the separation of organics and organic nitrogen.

Experimental Example 1 Evaluation of Total Nitrogen and Ammonia Removal in M-IEBR2 Process

In order to determine the effect of nitrogen removal when the M-IEBR2 process apparatus according to the present invention treated wastewater, the following experiment was performed.

Specifically, the M-IEBR2 process was performed by applying a potential of 3000 mV to each electrode as in Example 1, and the results of total nitrogen removal efficiency compared to the influent are shown in FIG. 2, and the results of the removal efficiency of ammonia are shown in FIG. It was.

As shown in FIG. 2 and FIG. 3, as a result of performing the M-IEBR2 process, the total nitrogen removal efficiency compared to the influent was about 82.8%, and the current density was 8.72 A / m ² , and the total nitrogen removal in the M-IEBR2 was shown. Is proportional to the difference of external potential. In addition, the ammonia removal efficiency also showed a tendency to increase as the external potential increased, showing a maximum removal efficiency of 83.4% at a current density of 8.72 A / m ² .

This shows superior nitrogen removal efficiency compared to the conventional M-IEBR process, which showed 53% and 64% ammonia removal efficiencies, and it was not affected by the ion exchange rate even with one cathode and anode. To show.

Encouragingly, the rate of ion exchange increased the ammonia load on the aerobic tank. Some nitrates were denitrated in the aerobic tank and most of the nitrates were transported through the anion exchange membrane to the denitrification tank according to the concentration gradient. As a result, as the removal efficiency of ammonia is improved, the removal efficiency of nitrate through denitrification is also improved.

In conclusion, the rate-changing step for the whole process can be referred to as the ion exchange rate of ammonia, and the removal efficiency of ammonia and nitrate can be further improved by applying an electric potential to increase the ion exchange rate of ammonia. In addition, the movement to the denitrification tank according to the simultaneous denitrification and nitrate concentration gradient in the aerobic tank was able to obtain the effect of preventing the use of unnecessary electrodes and power.

Therefore, the M-IEBR2 process according to the present invention, which changes the position of the electrode and reduces the number of electrodes and the number of power sources with respect to the existing M-IEBR process, can obtain an improved ammonia removal efficiency of up to 1.5 times. Since the ammonia and nitrate removal efficiency can be controlled according to the magnitude of the potential applied from the outside, it can be usefully used to remove ammonia from the wastewater.

Experimental Example 2 Evaluation of Organic Matter Removal in M-IEBR2 Process

M-IEBR2 process apparatus according to the present invention was carried out as follows to see the effect of removing the organic matter when the waste water treatment.

Specific experimental method was carried out in the same manner as in Experimental Example 1, the results of removing the organics are shown in FIG.

As shown in FIG. 4, as a result of performing the M-IEBR2 process after the start of operation, the organic matter removal efficiency was about 63.3-77.6%, and the organic matter contained more than 2,500 mg COD / L. This is due to the low load of nitrate in the denitrification tank, which was not sufficient to remove organic matter through denitrification, and is also a result of the hardly degradable organic matter contained in the waste water.

However, as shown in FIG. 4, as a result of performing the M-IEBR process regardless of the current density, high organic matter removal efficiency was obtained. In the case of low current density, anaerobic digestion is actively performed in the anaerobic tank, whereas in the case of high current density, the ion exchange rate is increased, and the rate of separation and oxidation of ammonia is increased, and the nitrate in the aerobic tank is moved through the anion exchange membrane by the concentration gradient. Therefore, it is believed that the simultaneous removal of organic matter and ammonia occurred due to the increased load of nitrates. In addition, it is thought that the decomposition reaction of organic matter due to bioelectrochemical reaction at the electrode also acted.

Therefore, compared with the conventional M-IEBR process, the M-IEBR2 process can remove organic materials more stably, and has an advantage of controlling the process regardless of the magnitude of the potential applied from the outside.

In conclusion, when combining the results of Experimental Example 1 and Experimental Example 2, the M-IEBR2 process according to the present invention can obtain an improved organic and nitrogen removal effect by applying a potential applied from the outside, from the outside It is possible to control the removal efficiency of organic matter and nitrogen from the wastewater by adjusting the magnitude of the potential applied, it can be useful for simultaneous removal of organic matter and nitrogen from the wastewater.

Claims (9)

An anaerobic tank into which wastewater is introduced;
An aerobic tank communicating with the anaerobic tank;
A denitrification tank communicating with the expiratory tank;
A cation exchange membrane communicating the anaerobic tank and the aerobic tank;
An anion exchange membrane in communication with the aerobic tank and the denitrification tank;
A potential device comprising a reduction electrode provided in the anaerobic tank and an anode provided in the aerobic tank;
A bioelectrochemical wastewater treatment apparatus capable of simultaneously removing organic matter and organic nitrogen, including an influent feed pipe communicating the anaerobic tank and the denitrification tank.
The method of claim 1,
By the potential difference generated in the reduction electrode installed in the anaerobic tank and the anode installed in the aerobic tank,
Bioelectrochemical wastewater treatment apparatus, characterized in that for improving the rate of passage of the ammonia from or contained in the waste water to the aerobic tank through the cation exchange membrane.
The method of claim 1,
The anaerobic tank uses a cathode and microorganisms installed in the anaerobic tank,
Bioelectrochemical wastewater treatment apparatus characterized by decomposing organic matter contained in the incoming wastewater.
The method of claim 1,
The aerobic tank uses an anode and microorganisms installed in the aerobic tank,
Bioelectrochemical wastewater treatment apparatus, characterized in that the ammonia flowing from the anaerobic tank through the cation exchange membrane to form nitrate.
The method of claim 1,
The aerobic tank uses an anode and microorganisms installed in the aerobic tank,
A bioelectrochemical wastewater treatment apparatus characterized by forming ammonia introduced from an anaerobic tank through a cation exchange membrane into nitrate, and then denitrifying the nitrate.
The method of claim 1,
The denitrification tank reacts the nitrates introduced from the aerobic tank through the anion exchange membrane with the organics in the wastewater introduced through the inlet transport pipe communicating with the anaerobic tank and the denitrification tank to oxidize the organics and denitrate the nitrates. Processing unit.
The method of claim 1,
When the ammonia flowing from the anaerobic tank through the cation exchange membrane in the aerobic tank to form a nitrate and then perform a denitrification reaction and the concentration of the remaining nitrate is saturated,
The nitrate is moved to the denitrification tank through the anion exchange membrane by the concentration gradient, and the nitrate reacts with the organic matter in the wastewater introduced through the influent feed pipe communicating with the anaerobic tank and the denitrification tank to oxidize and denitrate the organic matter. Electrochemical wastewater treatment device.
The method of claim 1,
The cathode is a bioelectrochemical wastewater treatment device, characterized in that formed of iron (iron).
Introducing wastewater containing organic matter and organic nitrogen into the anaerobic tank;
Supplying power to the potential device, decomposes the organic matter contained in the wastewater on the surface of the microbial layer formed on the cathode electrode provided in the anaerobic tank, induces denitrification of nitrate inside the microbial layer, and ammonia contained in the wastewater Moving to the aerobic tank through a cation exchange membrane communicating with the aerobic tank;
Supplying power to the potential device, decomposing organic matter on the surface of the microorganism layer formed on the microorganism suspended in the aerobic tank or the anode electrode provided in the aerobic tank, and generating ammonia, which is moved to the aerobic tank, in the step as nitrate;
Supplying power to the power supply device to denitrate the nitrate produced in the step inside the microbial layer formed on the anode provided in the aerobic tank; And
In this step, the remaining nitrate, which cannot be denitrated, is transferred to the denitrification tank through an anion exchange membrane communicating the aerobic tank and the denitrification tank by the concentration gradient, and the nitrate is transferred to the organic matter in the wastewater introduced through the influent feed pipe communicating the anaerobic tank and the denitrification tank. A method of treating wastewater at the same time, wherein the organic matter and organic nitrogen can be removed by oxidizing the organic material by reacting the same.

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