KR20130051251A - Microbial fuel cell using dye wastewater - Google Patents

Abstract

PURPOSE: A microbial fuel cell is provided to easily form a bio-film on the wide surface of a granular activated carbon, thereby having excellent battery efficiency and facilitating discoloration and purification of dye waste water. CONSTITUTION: A microbial fuel cell comprises a cathode and an anode which comprise a granular activated carbon; reaction containers of the positive electrode and negative electrode, which comprise dye waste water and microbial catalysts as an electrolyte; and an ion exchange film which divides the reaction containers of the positive electrode and negative electrode into a positive electrode part and negative electrode part. The reaction container comprises an air inlet for maintaining oxygen-saturated state of a positive electrode part and/or a nitrogen inlet for maintaining non-oxygen state of a negative electrode part. The specific surface area of the granular activated carbon is 500-1,500 m^2/g.

Description

Microbial Fuel Cell Using Dye Wastewater

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microbial fuel cell using dye wastewater as fuel. More specifically, the present invention includes an anode and a cathode fixed with granular activated carbon, and generates electric power by using organic matter in the dye wastewater as fuel. It relates to a microbial fuel cell that can treat dyed wastewater.

Microbial fuel cell is a device that converts the reducing power generated in the energy metabolism of the organism to electrical energy by using the organism or a part thereof, mainly produces the electricity by oxidizing organic and inorganic compounds using the microorganism as a catalyst. However, electricity production in microbial fuel cells is low so far, and rather than using it for electricity production, the focus is on the resolution of wastewater and toxic substances by microorganisms present in the electrodes.

The general textile dyeing industry wastewater consumes a large amount of water in the dyeing process to attach dyes to the fibers and has a large amount of wastewater discharge.The wastewater generated is high temperature and high alkali, and it is a pigment compound, a salt forming agent and a surfactant. It contains hardly degradable substances such as various organic polymer compounds, toxic substances, mutagenic substances, carcinogens and microbial growth inhibitors, and the water consumption and waste water characteristics are not constant depending on the type of fiber and dye used. However, the concentration of organic substances in the wastewater flowing into the wastewater treatment plant is very severe, and it is difficult to treat them.

Azo pigments present in dyeing wastewater are widely used pigments, which account for 60% of the total dyeing agent structure. They are very intractable molecules and are difficult to decompose. Chemical methods are used. However, these methods were expensive, produced toxic intermediates, and had low removal ability. Therefore, in order to overcome this point, the biological decolorization method using the strain began to attract attention. Therefore, many anaerobic or aerobic bacteria were found to be effective in discoloration of the dyeing wastewater, but there was still a problem of slow reaction speed and low stability and efficiency.

Recently, a bioelectrochemical system has been attracting attention for the decolorization of the azo pigment, an example of which is a microbial fuel cell has the advantage of treating the dyeing wastewater while producing power. Therefore, the inventors of the present invention have attempted to develop a microbial fuel cell using the dyeing wastewater as a substrate.

Therefore, the present invention is to provide a microbial fuel cell excellent in the function of the dye discoloration in the dye wastewater using the dye wastewater as a substrate.

In order to solve the above problems, the present invention comprises a cathode (cathode) and a cathode (anode) including granular activated carbon (granular activated carbon); And it provides a microbial fuel cell comprising a reaction tank of the positive electrode and the negative electrode including a dye wastewater and a microbial catalyst as an electrolyte therein.

In addition, the present invention by using the microbial fuel cell, injecting nitrogen to the negative electrode to make anaerobic conditions, the positive electrode continuously injected air to create a saturated oxygen state in the dye wastewater or electrochemically active bacteria introduced from the outside By using as a microbial catalyst and using organic or inorganic matter in the dyeing wastewater as a fuel provides a method for treating the dyeing wastewater while generating power.

The microbial fuel cell of the present invention can easily form a biofilm on a large surface area of particulate activated carbon, so that the cell efficiency is excellent, and the possibility of use in actual dyeing wastewater has been verified. It can be directly used for discoloration and purification of dyeing wastewater.

1 is a schematic diagram of a microbial fuel cell (GACB-MFC) according to Example 1 of the present invention.
Figure 2 is a schematic diagram of a microbial fuel cell (GACB-SCMFC) according to a second embodiment of the present invention.
Figure 3 is a graph of the voltage measurement results of Test Example 1 for the microbial fuel cell of Example 1.
Figure 4 is a graph of the voltage measurement results of Test Example 1 for the microbial fuel cell of Example 2.
5 is a graph of DO level measurement results according to the distance between electrodes for the microbial fuel cell of Example 2.
Figure 6 is a graph of the decolorization investigation results of the present invention microbial fuel cell of Test Example 2 for the microbial fuel cell of Example 1.
7 is a graph showing the results of decolorization of the control of the abiotic conditions of Test Example 2 for the microbial fuel cell of Example 1.
FIG. 8 is a graph showing the results of comparative experiments for the open circuit and the closed circuit of Test Example 2 for the microbial fuel cell of Example 1 (Acc = Anode at closed circuit (800 mV), Aoc = Anode at open circuit, Ccc = Cathode) at closed circuit (800 Hz) and Coc = Cathode at open circuit).
9 is a graph showing the decolorization and COD results of the present invention microbial fuel cell of Test Example 2 for the microbial fuel cell of Example 2. FIG.
10 is a graph showing the results of the COD change according to Experimental Example 3 for the microbial fuel cell of Example 1.
11 is a graph of the toxicity test results according to Test Example 4 for the microbial fuel cell of Example 1.
12 is a graph of toxicity test results according to Test Example 4 for the microbial fuel cell of Example 2.
13 is a graph showing the results of the pH change according to Test Example 5 for the microbial fuel cell of Example 1.
14 is a graph showing the results of the pH change according to Test Example 5 for the microbial fuel cell of Example 2.

The present invention comprises a cathode (cathode) and a cathode (anode) including granular activated carbon; And it provides a microbial fuel cell comprising a reaction tank of the positive electrode and the negative electrode including a dye wastewater and a microbial catalyst as an electrolyte therein.

The inventors of the present invention, while studying the microbial fuel cell using the dye wastewater as a substrate, when the fixed activated carbon used in the electrode is fixed, the biofilm of the microorganism is well formed on the large surface area of the particulate activated carbon is excellent metabolic efficiency of the microorganism And through this, the decomposition of the azo pigments in the dyeing wastewater and COD reduction effect is excellent, and confirmed that the present invention can be applied immediately without pretreatment of the dyeing wastewater was completed.

In one embodiment of the present invention, the microbial fuel cell may further include an ion exchange membrane to isolate the positive electrode and the negative electrode reaction tank to the positive electrode and the negative electrode. In the following examples, the microbial fuel cell further including an ion exchange membrane is described in Example 1, and the microbial fuel cell having a single chamber type without the ion exchange membrane is described in Example 2. The single chamber microbial fuel cell of Example 2 without the ion exchange membrane has the advantage of being able to treat higher capacity dyeing wastewater and reducing internal resistance.

In one embodiment of the present invention, since the negative electrode portion near the negative electrode of the microbial fuel cell is consumed while reducing oxygen to water in order to produce energy necessary for the growth of microorganisms, the reducing power produced in the metabolism of the microorganisms is rich in oxygen. It is good to stay anaerobic. Therefore, anaerobic conditions are formed at the cathode and aerobic conditions are formed at the anode.

Accordingly, the anode portion near the anode may further include an air inlet for maintaining an oxygen saturation state, and the cathode portion may further include a nitrogen inlet for maintaining an oxygen free state. However, in general, because the microorganisms of the negative electrode grow and consume dissolved oxygen, an anoxic state may be formed in the negative electrode without injecting nitrogen.

In another embodiment of the present invention, the granular activated carbon may be one having a specific surface area of 500 to 1500 m ² / g, but is not limited thereto. It may be fixed to the electrode through a method of inserting an electrode therein, which is embedded in a cylindrical cage, but is not limited thereto. The activated carbon may be formed at the bottom of the reactor in the form of a bed and form an electrode in such a manner that the electrode is inserted therein. It may be.

The positive electrode and the negative electrode can be used without particular limitation as long as they are electrodes used in conventional microbial fuel cells, and examples thereof include graphite electrodes such as graphite rods, graphite plates, or graphite nonwoven fabrics having a large surface area. Graphite, which is mainly used as an electrode material, is a hexagonal cyclic carbon compound, and only three of the six carbon atoms constituting the hexagonal ring are used for bonding between the rings, and the three do not form a bond, and thus have conductivity.

In order to minimize the resistance of the fuel cell itself, the microbial fuel cell of the present invention may include an ion exchange membrane between the anode reaction vessel and the cathode reaction vessel, and more specifically, the ion exchange membrane that isolates the anode and cathode reaction vessels may include nonwoven fabric, cotton, Microfiltration membranes, ultrafiltration membranes or glass wool can be used. More specifically, glass wool is more economical than conventional Nafion ion exchange membranes, and may be useful in the present invention because the internal resistance is reduced by reducing the clogging phenomenon by the microorganism and increasing the proton migration rate.

In the microbial fuel cell according to the present invention, the microbial catalyst may be used without particular limitation as long as it is a microorganism capable of generating an electric current by using organic or inorganic materials as a fuel and reducing power according to fuel consumption in a negative electrode reaction. That is, all microorganisms used in conventional microbial fuel cells can be used, and more specifically, Shewanella sp., Geobacter sp. And Rhodoferax sp. But are not limited thereto.

The microbial catalyst according to an embodiment of the present invention may use organic or inorganic materials inside the dyeing wastewater as an energy source, and may include dyeing wastewater as an electrolyte in the reaction tank in which the anode and the cathode are located. According to one embodiment of the invention, the organic or inorganic material present in the dyeing wastewater at the cathode is oxidized by a microbial catalyst, which produces excess electrons and protons. These electrons and protons decompose an azo bond of the dye present in the dye wastewater present as an electrolyte, thereby removing the color of the cathode chamber. Reductive decomposition of -N = N- bonds induces azo pigmentation under anaerobic conditions, and electrons and protons that reach the anode via an external circuit or glass wool decompose the azo bonds present in the dye wastewater dye at the anode, respectively. , Causes decolorization at the anode.

Accordingly, the present invention by using the microbial fuel cell, injecting nitrogen to the negative electrode to make anaerobic conditions, the positive injection of air continuously to create an oxygen saturation state in the dye wastewater or electrochemical activity introduced from the outside By using bacteria as a microbial catalyst and using organic or inorganic substances in dyeing wastewater as fuel, there is provided a method of generating electricity and treating wastewater at the same time.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the following examples. However, the following examples are intended to illustrate the contents of the present invention, but the scope of the present invention is not limited to the following examples. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

< Example  1> GACB -MFC ( granular activated carbon based microbial  fuel cell ) Produce

GACB-MFC (Granular Activated Carbon Basic-Microbial Fuel Cell) is a granular activated carbon (GAC), GC 8 × 30, 900 m ² / g, Hae Young Co wrapped in a cylindrical stainless steel cage (volume: 34 cm ³ ). , Busan, Korea) It consists of two glass bottles (250ml) with built-in electrodes. Both bottles are connected by glass bridges containing glass wool (Pyrex, USA) separators instead of Nafion membranes, which are fixed by clamps between two flat ends of a glass tube (inner diameter = 1.3 cm).

The GAC is placed inside a cylindrical stainless steel cage mesh and used as the cathode, with a similar electrode used as the anode. Graphite rods (1 cm in diameter) are inserted into the cathode and anode, and the anode is connected to an external resistor of 800 kΩ unless otherwise noted. 1 is a schematic diagram of a microbial fuel cell according to Example 1 of the present invention.

Cathode and anode were inoculated with bacteria present in the dyeing wastewater recovered from the dyeing wastewater plant (Daegu, Korea) and operated in fill & draw mode.

10 ml of aerobic sludge recovered from the dyeing wastewater plant was initially inoculated into the anode, and dyeing wastewater was further introduced to increase aerobic bacteria to promote bioanode formation.

The cathode was maintained in anaerobic conditions through a 10 minute nitrogen gas sparge at the beginning of operation, while the anode was sparged continuously with an aquarium pump (200 mL / min). The reaction solution was replaced every two days. After 3 weeks, a stable voltage was reached. As the dye wastewater was replaced, the output voltage was repeated, suggesting that the biofilms formed on the cathode and anode play a stable role. Dyeing wastewater was introduced to the cathode and anode without any manipulation unless otherwise indicated.

Measurements began two months after GACB-MFC operation, and all experiments were performed three times. GACB-MFC operation was performed at 30 ° C. The characteristics of the dye wastewater are as follows: pH = 12.4, COD = 2080 mg / l and color 488 Pt-Co units. One color unit is equivalent to 1 mg / l platinum present as chloroplatinate ion.

Abiotic control experiments were performed using autoclaved dyed wastewater without the operation of microbial fuel cells in the presence of GAC electrodes to confirm the adsorption effect of GAC. GAC electrodes were present in 250 ml vials and filled with autoclaved dye wastewater. Autoclaved stained wastewater was replaced daily and performed for 12 days. Abiotic control experiments were performed inside the laminar chamber to avoid discoloring effects by bacteria.

< Example  2> GACB -SCMFC ( granular activated carbon based single  chamber microbial fuel cell ) Produce

GACB-SCMFC (Particulate Activated Carbon Base-Single Chamber Microbial Fuel Cell) is an acrylic chamber (2.5L) containing granular activated carbon (GC 8 × 30, 900 m ² / g, Hae Young Co, Busan, Korea). Is done. In the anode, a GAC bed (volume = 100 cm ³ ) and four graphite rods (1 cm in diameter) are inserted into the GAC bed to serve as an electron collector. A cathode is a four-cylindrical stainless steel cage filled with GAC (total volume = 100 cm ³ ) in which graphite rods are inserted into each stainless steel cage as electron collectors. The cathode and the anode are connected to an external resistor of 50 kohms. 2 is a schematic diagram of a microbial fuel cell according to a second embodiment of the present invention.

The dyeing wastewater was continuously introduced into the lower part of the microbial fuel cell of Example 2 through the flow control pump, and flowed out from the middle part of the anode part after flowing the cathode part. The spilled wastewater was collected and analyzed. Dyeing wastewater was obtained from a comprehensive dyeing wastewater treatment plant (Daegu, Korea), there was a variety of dyeing wastewater mixture there was difficult to distinguish each component.

The anode was sprayed continuously with an aquarium pump (1.5 L / min). After 3 months of continuous MFC operation, a stable voltage was reached, all measurements were taken after 7 months of operation, and all experiments were performed three times. GACB-SCMFC operation was performed at 30 ° C. The characteristics of the dye wastewater are as follows: pH = 12.2, COD = 2200 mg / l and color 478 Pt-Co units. One color unit is equivalent to 1 mg / l platinum present as chloroplatinate ion.

< Test Example  1> voltage measurement

The voltage across the external resistor was measured with a digital multimeter (Agilent 34405A, USA) connected to a computer at 30-minute intervals. The power density was calculated according to various external resistances of 100 to 3000 mA. The internal resistance was calculated by the formula R _int = (OCV-V) / I, where OCV is the open circuit voltage, V is the voltage of the external resistor, and I is the current obtained.

The results related to the microbial fuel cell of Example 1 are shown in FIG. 3.

When the negative electrode and the positive electrode of the microbial fuel cell (GACB-MFC) of Example 1 were filled with the actual dyeing wastewater, electricity production gradually started to occur. The required nutrients of the bacteria were already present in the dyeing wastewater. During the first few days of operation, the voltage appeared very low because the biofilm on the cathode and anode was poorly formed. Referring to FIG. 3, the stable voltage (0.214V) appeared with a high power density of 1.7 W / m ³ when the external resistance was 800 kW after 3 weeks of operation of the microbial fuel cell, and an open circuit voltage. ) Was measured at 0.45 V. This suggests that a biofilm is formed at the cathode and the anode, thereby performing a stable role.

After 3 months of operation of the microbial fuel cell (GACB-SCMFC) of Example 2, when the electrode spacing was 2cm, the maximum power density was 8W / m ³ and the open circuit voltage (OCV) was 0.39V. . The results are shown in Fig. When the electrode interval I had a significant influence on the internal resistance and the output voltage, with reference to Table 1 below, if the electrode spacing is reduced from 5cm by 2cm, the power density was increased to 8W / m ³ in 3W / m ^3. However, if the electrode spacing is further reduced from 2 cm to 1 cm, the oxygen migration from the anode to the cathode will affect the output voltage to a lower level.

Electrode distance  ( cm ) R _int  (Ω) Power density  (W / m ³ ) 5
3.5
2
One 96
68
47
39 3
5.12
8
5.44

5 shows that when the electrode spacing is 1 cm, the oxygen diffusion from the anode to the cathode increases than when the electrode spacing is 2 cm, where the DO level of the anode remains unchanged. Oxygen migration to the cathode is known to severely inhibit anaerobic respiration and electron production.

Table 2 shows the internal resistance (R _int ) and the output voltage according to the number of carbon electrodes (electron collectors) inserted into the GAC bed cathode. As the number of graphite rods decreased from 4 to 1, the output voltage decreased from 8 W / m ³ to 2.5 W / m ³ and the internal resistance increased from 47 kW to 110 kW, respectively. If the electron transfer from the cathode to the anode is not smooth, it causes high resistance, and accordingly, the multi-cathode composite in the GAC bed is considered to have an effect of reducing the resistance by smoothing electron transfer. However, when the graphite electrodes were increased to five, there was no significant change in the output voltage, and four graphite electrodes were judged to be sufficient to carry electrons in the GAC bed.

No of graphite  electrodes inserted into GAC  bed ( anode ) R _int  (Ω) Power density  (W / m ³ )
One
2
3
4 110
75
60
47 2.5
5
6.8
8

< Test Example  2> chromaticity change observation

Chromaticity measurements were performed using the Platinum-Cobalt Standard Method. Prior to chromaticity analysis, the pH of the sample was adjusted to 7.6 as suggested by the NCASI method and filtered with 0.4 micron filter paper. Deionized water was used as the blank. The instrument (Hach, DR / 2500) was calibrated using standard Platinum-Cobalt solution. 10 ml of filtered sample was filled into the sample cell and the absorbance was measured at 465 nm. Decolorization activity was calculated by the following formula.

% Decolorization = (AB) / A x 100, where A is the initial absorbance and B is the observed absorbance.

The discoloration rate of the actual dye wastewater at 800 kPa condition of external resistance of the microbial fuel cell (GACB-MFC) of Example 1 was investigated at intervals of 12 hours. Related results are shown in FIGS. 6 and 7.

As shown in FIG. 6, a decolorization rate of 73% was observed after 48 hours at the cathode, and a decolorization rate of 77% was observed at the anode. All of the decolorization rate measurements were measured two months after the microbial fuel cell of Example 1, the activated carbon particles of the two electrodes are already adsorbed by the dye, so that the adsorption effect by the activated carbon particles of the electrode was not considered. . 7 shows the adsorption effect of GAC electrodes in abiotic conditions (high pressure sterilized dye wastewater).

At the cathode, organic and inorganic materials present in the dyeing wastewater are oxidized by bacteria, which produce excess electrons and protons. These electrons and protons decompose the azo bonds of the pigment and remove the color of the cathode chamber. The reductive degradation of -N = N- bonds leads to azo pigmentation under anaerobic conditions, which is associated with direct electron transfer through enzymes during bacterial catabolism linked to energy conversion with the azo pigment as the final electron acceptor. Electrons and protons that reach the anode through external circuits and glass wool decompose the azo bonds present in the proton pigment, respectively, and cause a discoloration reaction at the anode.

In an open circuit (infinite external resistance), referring to FIG. 8, 66% of the discoloration rate was observed at the cathode after 48 hours of microbial fuel cell operation, whereas only 51% of the discoloration rate was observed at the anode. It has been reported that the lower the external resistance, the higher the coulomb from the substrate, due to the increased substrate conversion rate at higher resistances during microbial fuel cell operation. As a result, the substrate conversion rate at the cathode in the open circuit is lower, and the electron production is also lower than in the closed circuit, resulting in a decrease in decolorization rate (see FIG. 8). In the open circuit anode (circuit short) there is no electron movement to the anode. Thus, discoloration of the anode is noticeably reduced in open circuit conditions, suggesting an electrical effect in anode discoloration. However, at open circuit voltage, 51% of decolorization occurred, which may be due to aerobic decomposition of the dye wastewater due to aerobic organisms present in the anode chamber. Also, when the positive electrode was separated from the microbial fuel cell, the decolorization rate decreased from 51% to 39% after 48 hours. This means that in OCV mode, unreacted electrons (free electrons) in the cathode move through the glass wool to the anode and contribute to decolorization of the anode.

The discoloration of the actual dye wastewater of the microbial fuel cell (GACB-SCMFC) of Example 2 was investigated at 12 hour intervals. Related results are shown in FIG. 9. As shown in FIG. 9, a decolorization rate of 75% was observed after 48 hours of HRT (hydraulic residence time). All bleaching rate measurements were taken 7 months after GACB-SCMFC operation. Therefore, since the activated carbon particles of the two electrodes are already adsorbed by the dye and saturated, the adsorption effect of the activated carbon particles of the electrode need not be considered.

When the dye wastewater passes through the cathode, the organic and inorganic materials present in the dye wastewater are oxidized by the anaerobic bacteria present in the dye wastewater, which produces excess electrons and protons. These electrons and protons decompose the azo bonds of the pigment, thus removing the color of the dye wastewater in the negative electrode portion. The reductive degradation of -N = N- bonds leads to azo pigmentation under anaerobic conditions, which is associated with direct electron transfer through enzymes during bacterial catabolism linked to energy conversion with the azo pigment as the final electron acceptor. Pigments that are not degraded at the cathode are decomposed by aerobic treatment using electrons and protons transferred from the cathode through an external circuit at the anode. While it is difficult to completely decompose the pigment using aerobic biological treatment, the microbial fuel cell of the present invention exhibits high chromaticity removal rate by the sequential anaerobic-aerobic treatment of the dye wastewater.

< Test Example  3> COD ( Chemical Oxygen Demand Change observation

COD was measured using the Reactor Digestion Method using the Hach DR / 2500 (Hach, Loveland, CO, USA), and dissolved oxygen was measured using a DO meter (HI 91410, Hanna Instruments, USA).

The reduction of COD in the negative electrode and the positive electrode of the microbial fuel cell (GACB-MFC) of Example 1 was measured according to the holding time. Referring to FIG. 10, after 48 hours of operation of the microbial fuel cell, a 75% COD reduction was observed at the cathode and a 76% reduction was observed at the anode. Typical aerobic and bioelectrochemical treatment combinations result in increased COD reduction at the anode. In addition, the reduction of COD at the anode is higher than at the cathode because of the growth of heterotrophs that use oxygen at the anode to oxidize biodegradable COD.

The COD reduction of the microbial fuel cell (GACB-SCMFC) of Example 2 was also measured according to HRT. Referring to FIG. 9, at 48 hours of HRT, 71% of COD was removed. The dyeing wastewater is treated under anaerobic conditions so that anaerobic bacteria can biodegrade organic or inorganic substances in the cathode chamber, and then the wastewater subjected to anaerobic treatment is subjected to aerobic conditions while passing through the anode chamber. High COD removal rates are obtained because the anode process after the normal cathode process acts as an additional aerobic finishing step process. The anode of the microbial fuel cell has the ability to anaerobicly remove COD, and when the dye-treated wastewater is transferred from the cathode to the anode chamber, a heterotrophic organism that uses oxygen at the anode to oxidize the biodegradable COD Remove additionally.

< Test Example  4> toxicity test

Toxicity tests on mixed bacterial cultures of stained wastewater (Biogas plant, Paju, Korea) were performed using a spectrophotometer (Hach, Loveland, Co., USA) through the resazurin reduction method. The method is based on the reduction by bacterial respiration of the redox-active pigment resazurin. Respiration is the process of producing ATP (adenosine triphosphate) using the oxidative energy of the electron donor from the external electron acceptor. Electrons delivered from the electron donor are delivered to the final electron acceptor via a series of electron transport proteins inserted into the cell membrane. Redox-active pigments, such as Resazurin, act as an alternate electron acceptor by oxidizing one of the membrane proteins. When the pigment is reduced, Resazurin changes color from blue to pink, and this color change is very rapid and easily visible to the naked eye. Toxic substances inhibit Resazurin reduction. Chemical catalysts (glutaraldehyde) can be added to shorten the reaction time and the absorbance for color change was measured at 603 nm.

Inhibition is calculated by the following formula:% I = [1- (ΔA _sample / ΔA _control )] × 100, where 'ΔA _sample = initial absorbance-final absorbance'.

Because colonies give organisms greater adaptability to environmental stresses such as pollution due to their genetic diversity, natural environmental microorganisms tend to exist in clusters for mutual benefit and protection. Therefore, in bacterial studies, mixed bacterial cultures were used in place of single bacterial cultures.

The Resazurin test for toxicity measures microorganisms' dehydrogenase activity by accepting electrons flowing in cellular metabolism. Toxic substances inhibit the reduction of Resazurin.

Table 3 shows the experimental results of the microbial fuel cell (GACB-MFC) of Example 1.

Table 3 shows the results of toxicity measurements of the dyeing wastewater.

Time  (h) % inhibition Anode Cathode 0 61 ± 10 61 ± 10 24 24 ± 6 7.3 ± 3 48 18.6 ± 3 5.7 ± 2

Referring to Table 1, the initial staining wastewater showed 61 ± 10% inhibition of Resazurin reduction (no color change from blue to pink). This means that the initial dye wastewater contains acute toxic chemicals. These acute toxic substances cause dyeing wastewater to be a threat to the environment.

After 24 hours of operation of the microbial fuel cell of Example 1, the anode effluent showed an inhibition rate of 7.3 ± 3% (color changed from blue to pink). This means it is almost non-toxic. In the anode chamber, the pigment was cut due to the electrons reached due to the external circuit. In general, these intermediates are very toxic and are further degraded into non-toxic compounds by aerobic bacteria present at the anode. Cathode effluent shows 24 ± 6% and 18.6 ± 4% inhibition rates after 24 and 48 hours, respectively. Thus, the negative effluent after 48 hours is three times less toxic than the dyed wastewater before the microbial fuel cell operation of Example 1. FIG. 11 shows that the negative electrode concentration increased over time in inoculated MFC (inoculated MFC), indicating a biological effect on oxygen transport. Referring to FIG. 11, it can be seen that the DO concentration is slowly increased by about 2 times compared to the inoculated microbial fuel cell (inoculated MFC) which is not inoculated (high pressure sterilized dye wastewater, uninoculated MFC). This is because a large amount of dissolved oxygen is consumed by the aerobic bacteria present in the cathode chamber, resulting in the decomposition of the intermediate produced by anaerobic decomposition.

Toxicity test results for the microbial fuel cell (GACB-SCMFC) of Example 2 are shown in FIG. 12. Initial staining wastewater showed 59 ± 9% inhibition of Resazurin reduction (no color change from blue to pink). This means that the initial dye wastewater contains acute toxic chemicals.

After 48 hours of operation of the microbial fuel cell of Example 2, the positive electrode effluent showed an inhibition rate of 7.9 ± 2% (color changed from blue to pink). This means it is almost non-toxic. In the cell of Example 2 above, the pigment material was removed by the anaerobic bacteria of the negative electrode, and often the toxic intermediates produced were further degraded into non-toxic compounds by the aerobic bacteria present on the positive electrode.

< Test Example  5> At the anode and cathode during microbial fuel cell operation pH  change

pH was measured using a digital pH meter (Hanna Instruments, USA).

Referring to Figure 13, it was observed that the pH of the negative electrode and the positive electrode is significantly reduced during the operation of the microbial fuel cell of Example 1. After 48 hours of operation, the pH of the cathode was reduced from 12.4 to 7.2 and the pH of the anode was reduced to 8. It was also observed that the cathode pH was lower than the anode pH, as H ⁺ ions migrate from cathode to anode as can be seen in a typical microbial fuel cell. To confirm the effect of pH on bleaching and COD removal, the pH of the dyeing wastewater was adjusted from 12.4 to 7. However, even after pH adjustment, there was no effect on decolorization and COD removal, and it was confirmed that there was no need for pH adjustment in the operation of the microbial fuel cell of the present invention.

Experimental results for the microbial fuel cell (GACB-SCMFC) of Example 2 are shown in FIG. 14. Referring to FIG. 14, it can be seen that the pH of the dye wastewater decreased from 12.2 to 8 after 48 hours of operation of the microbial fuel cell. In addition, in the case of Example 2, it was found that there is no need for pH adjustment in the operation of the microbial fuel cell.

Having described the specific parts of the present invention in detail, it will be apparent to those skilled in the art that such specific descriptions are merely preferred embodiments, and thus the scope of the present invention is not limited thereto. will be. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (8)

A cathode and a cathode including granular activated carbon; And
A microbial fuel cell comprising a reaction tank of the positive electrode and the negative electrode including a dye wastewater and a microbial catalyst as an electrolyte therein.
The method of claim 1,
Microbial fuel cell further comprises an ion exchange membrane isolating the positive and negative electrode reaction tank to the positive electrode and the negative electrode.
The method according to claim 1 or 2,
The reactor is a microbial fuel cell further comprises an air inlet for maintaining the oxygen saturated state of the positive electrode.
The method according to claim 1 or 2,
The reactor is a microbial fuel cell further comprises a nitrogen inlet for maintaining an anoxic state of the negative electrode.
The method according to claim 1 or 2,
The specific surface area of the particulate activated carbon is 500 to 1500 m ² / g microbial fuel cell.
The method according to claim 1 or 2,
The positive electrode and the negative electrode is a microbial fuel cell that is a graphite electrode.
The method of claim 2,
The ion exchange membrane is glass wool (glass wool) microbial fuel cell.
Using the microbial fuel cell according to claim 1 or 2, injecting nitrogen into the negative electrode to create anaerobic conditions, and continuously injected air to the positive electrode to create an oxygen saturation state present in the dyeing wastewater or flowing from outside A method for treating dyed wastewater while producing electricity by using electrochemically active bacteria as a microbial catalyst and using organic or inorganic substances in the dye wastewater as fuel.

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