KR102529644B1 - Method and device for waste water treatment based on anaerobic digestion - Google Patents

Abstract

The present invention relates to a method for treating toxic wastewater based on anaerobic digestion and an apparatus for treating toxic wastewater for performing the method, and more specifically, in a method for treating toxic wastewater based on anaerobic digestion, wherein the toxic wastewater It relates to a toxic wastewater treatment method based on anaerobic digestion, characterized in that a conductive carrier is added to the introduced anaerobic digestion tank, and a toxic wastewater treatment apparatus for carrying out the method.
According to the present invention, even for wastewater having poor environmental conditions such as low pH conditions, high concentration organic waste and ammonia nitrogen content, the effect of reducing toxicity inhibition in the system can be achieved through the expression of a symbiotic relationship between electroactive microorganisms, , Therefore, it is possible to perform the wastewater treatment and biogas production process more effectively in the winter season of the existing wastewater treatment plant or in the event of an inflow accident of toxic substances or in the initial operation condition.

Description

Toxic wastewater treatment method and toxic wastewater treatment device based on anaerobic digestion {Method and device for waste water treatment based on anaerobic digestion}

The present invention relates to a method and apparatus for treating toxic wastewater based on anaerobic digestion.

Recently, with the increase in organic waste such as food waste and sewage sludge, the need for a method for properly managing organic waste has emerged. As conventional organic waste treatment methods, methods such as ocean dumping, incineration, landfill, land spreading, etc. have been used. it is becoming necessary

Therefore, an anaerobic digestion treatment method capable of reducing the amount of sludge generated in processing organic waste and producing biogas containing methane gas usable as a fuel is drawing attention. The anaerobic digestion method treats organic waste under anaerobic conditions, and has the advantage of excellent digestion efficiency of organic matter and further recovery of biogas.

In conventional anaerobic digestion systems, when the concentration or load of the inflowing waste increases, the pH in the system decreases, which causes the failure of the digester operation, so there is a need to solve this problem to build the stability of the digester . In this regard, in the prior art, when waste such as sewage sludge having a high protein content is introduced, the concentration of ammonia nitrogen increases to solve the problem of causing difficulty in operating the digester, adjusting the load of the waste entering the system or , or attempts to artificially lower the nitrogen concentration have been made.

Specifically, the technologies for securing the stability of anaerobic digestion system operation under conventional toxic conditions include a technology for injecting alkalinity substances of bicarbonate to prevent a significantly low pH in advance, and reducing or diluting the inflow waste load into the system There are ways to lower the concentration of toxic substances by doing so. However, the first method has a problem in that economic efficiency is low because chemicals are artificially introduced, and the second method is low in effectiveness in that the capacity of the digester is excessively increased in order to treat the entire amount of inflow waste generated There is a problem.

In this regard, an anaerobic digestion method to increase overall digestion efficiency and reduce operating and management costs by adjusting the alkalinity of bicarbonate in the anaerobic digester to an appropriate level has been disclosed (Patent Document 1), and the ammonium nitrogen concentration in the anaerobic digester is also at an appropriate level An anaerobic digestion method to achieve a similar effect by controlling has been disclosed (Patent Document 2).

Patent Document 1: Republic of Korea Patent Registration No. 10-0994193 Patent Document 2: Republic of Korea Patent Registration No. 10-1002386

Therefore, in the present invention, in order to solve the problems of the prior art, despite the toxic conditions of the wastewater of low pH, high concentration of ammonia nitrogen and organic matter concentration conditions, stable and effective performance without separate chemical administration or increase in digester capacity It is intended to provide a toxic wastewater treatment method and a toxic wastewater treatment device based on anaerobic digestion that can be operated.

In order to solve the above problems, the present invention

In the toxic wastewater treatment method based on anaerobic digestion,

It provides a method for treating toxic wastewater based on anaerobic digestion, characterized in that a conductive carrier is added to the anaerobic digestion tank into which the toxic wastewater flows.

According to one embodiment of the present invention, the conductive carrier may be activated carbon.

According to another embodiment of the present invention, the activated carbon may be coal-based activated carbon or coconut-based activated carbon.

According to another embodiment of the present invention, the average particle diameter of the activated carbon may be 0.8 mm to 2.2 mm.

According to another embodiment of the present invention, the amount of the conductive carrier added may be 0.1 g to 0.4 g per 1 g of dry weight of dry sludge in toxic wastewater.

According to another embodiment of the present invention, the toxic substance in the toxic wastewater may be selected from the group consisting of acetic acid, propionic acid, and mixtures thereof.

According to another embodiment of the present invention, the concentration of the acetic acid per 1 liter of the toxic wastewater may be 2 g to 12 g, and the concentration of the propionic acid may be 0.5 g to 2.0 g.

According to another embodiment of the present invention, the toxic wastewater may have a pH of 5 to 7 and an ammonia concentration of 110 mg to 150 mg per liter of the toxic wastewater.

According to another embodiment of the present invention, microorganisms that build a mutually symbiotic relationship can be attached to the surface of the conductive carrier by the addition of the conductive carrier.

According to another embodiment of the present invention, the microorganisms that establish the mutual symbiotic relationship may be Geobacter species microorganisms and Methanosarcina microorganisms.

According to another embodiment of the present invention, methane gas is generated as biogas by the wastewater treatment method, and an electric current may be generated.

In addition, the present invention, in order to solve the above other problems,

A digestion tank accommodating therein toxic wastewater and electroactive microorganisms that anaerobically digest the toxic wastewater;

a conductive carrier disposed inside the digester and to which the electroactive microorganism is attached to a surface thereof;

a working electrode to which, when a predetermined potential is applied, electron-generating microorganisms generating electrons by oxidizing toxic substances in the toxic wastewater among the electroactive microorganisms are attached;

a counter electrode to which electrons generated from the working electrode are introduced and to which electron-accepting microorganisms that receive the electrons from among the electroactive microorganisms and reduce carbon dioxide in the toxic wastewater to methane are attached;

a reference electrode maintaining a predetermined reference potential; and

a constant potential device that maintains the potential of the working electrode and the reference potential constant and measures the magnitude of the current in order to evaluate the degree of activity of the electroactive microorganisms proportional to the magnitude of the current, which is the flow of electrons;

It provides a toxic wastewater treatment device comprising a.

According to one embodiment of the present invention, a purging unit for purging the inside of the digester may be further included.

According to another embodiment of the present invention, it is disposed inside the digester, and may further include an agitator for mixing the toxic wastewater and the electroactive microorganism.

According to another embodiment of the present invention, the electron generating microorganism may be a Geobacter species microorganism, and the electron accepting microorganism may be a microorganism of the genus Methanosarcina .

According to the present invention, even for wastewater having poor environmental conditions such as low pH conditions, high concentration organic waste and ammonia nitrogen content, the effect of reducing toxicity inhibition in the system can be achieved through the expression of a symbiotic relationship between electroactive microorganisms, , It is possible to evaluate and diagnose the performance of the system through the measurement of oxidation and reduction potentials in real time using a constant potential device, and therefore, more effectively treat wastewater in the winter of the existing wastewater treatment plant or in the event of an inflow accident of toxic substances or in initial operating conditions. and a biogas production process.

1 is a graph showing accumulated methane production over time at pH 5 and 7 and acetic acid concentrations of 4 g/L and 12 g/L in the case of samples without activated carbon and activated carbon having different average particle diameters added am.
2a and 2b are graphs showing the average methane production rate (2a) and methane conversion rate (2b) of the inlet substrate for each sample under various conditions.
3 is a diagram showing the results of microbial cloning analysis for each sample according to Example 1;
4 is a diagram showing the number of microbial clones for each sample according to Example 1;
5 is a diagram showing the degree of distribution of Proteobacteria in each sample among microorganisms according to Example 1;
6 is a graph showing the number of clones of Geobacter species among Delta- proteobacteria for each sample according to Example 1.
7 is Geobacter It is a diagram showing a taxonomic phylogenetic diagram of methane candidate bacteria capable of producing methane through a mechanism of directly receiving electrons through species and activated carbon.
8 is a view showing an oxidation and reduction reaction measuring device using a three-electrode cell to present evidence for the activity of electroactive microorganisms in a batch-type anaerobic digestion device.
FIG. 9 is a diagram illustrating measurement results of CV and LSV measured using the apparatus shown in FIG. 8 .
10 is a schematic configuration diagram of an apparatus according to the present invention.

Hereinafter, the present invention will be described in more detail.

The present invention has been devised to solve the problems of the conventional anaerobic digestion system, that is, the problem of poor digestion tank stability due to a decrease in pH and an increase in ammonia nitrogen concentration in the system, specifically,

In the toxic wastewater treatment method based on anaerobic digestion,

It relates to a method for treating toxic wastewater based on anaerobic digestion, characterized in that a conductive carrier is added to an anaerobic digestion tank into which the toxic wastewater flows.

As described in detail through the examples to be described later, the toxic environment that inhibits methane production is alleviated by the addition of the conductive carrier, which is because the adaptability of methanogenic microorganisms to low pH is increased by the addition of the conductive carrier. judged Furthermore, the symbiotic relationship between specific microorganisms that generate current is further strengthened by the addition of the conductive carrier, and through this, more effective wastewater treatment and performance of the anaerobic digestion system can be quickly grasped.

Activated carbon may be used as the conductive carrier. As the activated carbon, although not limited thereto, coal-based activated carbon or coconut-based activated carbon may be used.

On the other hand, the average particle diameter of the added activated carbon affects the rate of methane gas generation generated by wastewater treatment. Preferably, when the average particle diameter of the activated carbon is 0.8 mm to 2.2 mm, smooth methane gas generation rate can be achieved.

In addition, the addition amount of the conductive carrier may be 0.1 to 0.4 g per 1 g of dry weight of dry sludge in toxic wastewater. If it exceeds, it is not preferable because there is a problem that the methane production efficiency is lower than that of the case where the conductive carrier is not added.

In the present invention, toxic substances that cause a toxic environment that inhibits methane production in the wastewater include, but are not limited to, acetic acid, propionic acid, and mixtures thereof. In this case, the concentration of the acetic acid per liter of the toxic wastewater may be 2 g to 12 g, and the concentration of the propionic acid may be 0.5 g to 2.0 g. Furthermore, the method according to the present invention can be smoothly applied to wastewater having a pH of about 5 to 7 and wastewater containing a high concentration of ammonia of 110 mg/L to 150 mg/L.

As will be described in detail through examples to be described later, a symbiotic relationship between specific microorganisms can be established by the addition of the conductive carrier, and the microorganisms that have established such a symbiotic relationship can attach to the surface of the conductive carrier. In particular, the symbiotic relationship generates electricity by anaerobic digestion and is friendly to the formation of symbiotic relationships with other microorganisms Geobacter ( Geobacter ) Species microorganisms, Methanosarcina ( Methanosarcina ) Which can be a mutual symbiotic relationship between microorganisms Bar, since Geobacter species receive electrons directly through conductive cilia to establish a symbiotic relationship with other microorganisms, it is advantageous to build a symbiotic relationship by adding activated carbon, which exhibits much higher conductivity than biological cilia of Geobacter species. This is because, in the case of microorganisms of the genus Methanosarcina , it has been reported that they can reduce carbon dioxide to methane by directly receiving electrons in addition to hydrogen and acetic acid.

Therefore, according to the wastewater treatment method according to the present invention, current can be generated with excellent efficiency through the expression of a symbiotic relationship mechanism between electroactive microorganisms even in wastewater in a harsh environment, and methane gas is generated as biogas. possible.

On the other hand, the present invention also provides a toxic wastewater treatment device based on anaerobic digestion, the device according to the present invention,

A digestion tank accommodating therein toxic wastewater and electroactive microorganisms that anaerobically digest the toxic wastewater;

a conductive carrier disposed inside the digester and to which the electroactive microorganism is attached to a surface thereof;

a working electrode to which, when a predetermined potential is applied, electron-generating microorganisms generating electrons by oxidizing toxic substances in the toxic wastewater among the electroactive microorganisms are attached;

a counter electrode to which electrons generated from the working electrode are introduced and to which electron-accepting microorganisms that receive the electrons from among the electroactive microorganisms and reduce carbon dioxide in the toxic wastewater to methane are attached;

a reference electrode maintaining a predetermined reference potential; and

a constant potential device that maintains the potential of the working electrode and the reference potential constant and measures the magnitude of the current in order to evaluate the degree of activity of the electroactive microorganisms proportional to the magnitude of the current, which is the flow of electrons;

includes

10 shows a schematic configuration diagram of the apparatus according to the present invention, and referring to FIG. 10, toxic wastewater 5 and electroactive microorganisms for anaerobic digestion of the toxic wastewater are accommodated inside the digester. A conductive carrier 6 is disposed inside the digester, and electroactive microorganisms are attached to the surface of the conductive carrier. As described above, examples of such electroactive microorganisms include microorganisms of the species Geobacter and microorganisms of the genus Methanosarcina , which can easily establish a symbiotic relationship.

On the other hand, the digester includes electrodes to which a potential is applied, and when a predetermined potential is applied, a working electrode to which electron-generating microorganisms that generate electrons by oxidizing toxic substances in the toxic wastewater among the electroactive microorganisms are attached ), a counter electrode (3) to which the electrons generated from the working electrode (2) are introduced and to which electron-accepting microorganisms that receive electrons from among the electroactive microorganisms and reduce carbon dioxide in the toxic wastewater to methane are attached, and A reference electrode 4 maintaining a predetermined reference potential is included.

At this time, as the electron generating microorganism attached to the working electrode (2), a microorganism of the species Geobacter is attached, and as an electron accepting microorganism attached to the counter electrode (3), a microorganism of the genus Methanosarcina is used. can be used

Furthermore, the potential of the working electrode 2 and the reference potential are kept constant, and the magnitude of the current is measured in order to evaluate the degree of activity of the electroactive microorganisms, which is proportional to the magnitude of the current, which is the flow of electrons. A constant potential potential (potenstat, 1) is included. In particular, the potentiostat 1 measures oxidation and reduction potentials in real time, thereby enabling real-time diagnosis of whether or not system performance is maintained smoothly and whether or not there is an abnormality in the system.

On the other hand, in order to facilitate anaerobic digestion, a purging unit for purging the inside of the digester under anaerobic conditions may be included, and is also disposed inside the digester, and the toxic wastewater and the electroactive microorganism. An agitator (7) may be further included.

In addition, in the device according to the present invention, matters related to the type, average particle diameter and addition amount of the conductive carrier, and properties of toxic wastewater are as described above.

Hereinafter, the present invention will be described in more detail through examples, but the following examples are only for helping understanding of the present invention, and do not limit the scope of the present invention.

Example 1. Conductivity carrier committed batch Mitigation of biogas toxicity in anaerobic digestion systems

Activated carbon (Samchully, density 0.43-0.48 g/mL, specific surface area 950 m ² /d, particle diameter 1.18-1.41 mm) was used as a conductive carrier. Experiments were conducted to investigate the effect of the size of the activated carbon on the methane production rate and the effect of substrates other than acetic acid, such as glucose, on the methane production rate. By filtering using a sieve, three types of activated carbon having an average particle diameter of 0.8, 1.6, and 2.2 mm were used separately. Furthermore, as a fermentable substrate other than acetic acid, 4 g/L of glucose was used as a carbon source.

In the anaerobic digester operation, an excessive amount of inlet substrate is injected, and as a result, hydrogen is not consumed during the fermentation process and organic acids are accumulated. Therefore, the characteristics of methane generation depending on whether or not activated carbon was injected were identified under the assumption that the system pH was low (pH 5) and the substrate was injected in excess (12 g/L).

Specifically, a 100 mL test bottle was first inoculated with 20 mL of the inoculation sludge being cultured in this laboratory (while still culturing the sludge collected from the digester of the Jungnang Sewage Treatment Plant in a laboratory incubator at 35 ° C, waiting until gas generation ceased, used as inoculation sludge), and 30 mL of acetic acid (4 g/L)-based substrate was injected (status per 1 liter of influent is CH ₃ COOH 4 g, NaHCO ₃ 5 g, NH ₄ Cl 0.23 g, KH ₂ PO ₄ 0.05 g, MgSO ₄ 7H ₂ O 0.05 g). Subsequently, 1.0 g of activated carbon was put into the test bottle according to whether or not the activated carbon was injected. The pH of the initial culture medium was adjusted to 7, and the cells requiring low pH conditions were adjusted to pH 5 using 1 N hydrochloric acid. The upper space of the test bottle was purged with nitrogen for 5 minutes, closed with a rubber stopper, and then the test bottle was left and reacted in an incubator at 35 ° C., and the gas generation amount and gas properties were analyzed for each time period.

1 is a graph showing accumulated methane production over time at pH 5 and 7 and acetic acid concentrations of 4 g/L and 12 g/L in the case of samples without activated carbon and activated carbon having different average particle diameters added am.

Referring to FIG. 1, it can be seen that the methane production rate is faster when activated carbon is added than when it is not. In the case of no input, it appears to be almost twice as slow as 55 days. On the other hand, the methane generation characteristics according to the size of the activated carbon considering the relative difference in specific surface area showed no significant change in the range of average particle diameter of 0.8 mm to 2.2 mm.

On the other hand, when glucose, a fermentable substrate, was added, the rate of methane production was similar regardless of whether activated carbon was added. In addition, the time point at which the cumulative methane production amount was maximum was also found to be about 15 days earlier than that using acetic acid.

In the case of pH 5, it was found that the methane production rate was slightly faster when activated carbon was added. In addition, the time point at which methane is generated (lag phase) was also found to be further shortened by 2-3 days when activated carbon was used. This is considered to be because the adaptability of methane microorganisms to low pH was increased through activated carbon.

It was found that the methane production rate increased when activated carbon was introduced even in an environment where the acetic acid concentration was maintained three times higher than the existing acetic acid concentration, that is, in an excessive inflow substrate load. The point at which the cumulative methane production was maximized was also found to be about 5 days earlier when activated carbon was added than when it was not.

As a result, it can be seen that activated carbon exhibits a mitigating effect on the inhibition of methane production even under conditions of low pH and high influent substrate concentration.

2a and 2b are graphs showing the average methane production rate (2a) and methane conversion rate (2b) of the inlet substrate for each sample under various conditions. Referring to FIG. 2a, the methane production rate was the highest at about 1.6-1.8 mL-CH ₄ /d when activated carbon was added and when glucose was used as a substrate (C: condition without adding activated carbon; 16: 16 mm average particle diameter) Conditions of addition of activated carbon; 5N: No addition of activated carbon and pH 5 conditions; 5G: Addition of activated carbon and conditions of pH 5; 12N: No addition of activated carbon and conditions of 12 g/L acetic acid; 12G: Addition of activated carbon and conditions of 12 g/L acetic acid; GN : no activated carbon and 4 g/L glucose condition; GG: added activated carbon and 4 g/L glucose condition). On the other hand, it can be seen that the average methane production rate is lowered when activated carbon is not added or under a substrate with high pH and acetic acid concentration, but when activated carbon is added, the 150-200% methanogenesis inhibition phenomenon is alleviated.

On the other hand, in the case of the methane conversion rate compared to the inlet substrate (FIG. 2b), both the control group and the experimental group injected with activated carbon were about 70%, whereas the pH 5 and 12 g/L high concentration acetic acid inlet substrate was low at 40-55%. This is believed to be due to the inhibition of methane microorganisms. In addition, the overall methane conversion rate was similar regardless of whether activated carbon was added (when activated carbon was not added, the methane reaction time was relatively long), and when glucose was used as a substrate, it was 55-60% regardless of activated carbon input. The methane conversion rate of

Example 2. Conductivity carrier committed batch Establishment of symbiotic relationship between electroactive microorganisms in anaerobic digestion system

In order to identify microorganisms immobilized in the batch-type anaerobic digestion apparatus into which the carrier was introduced in Example 1, after the batch-type methane production reaction was completed, 2 mL of the bulk solution (including 0.5 mL GAC) was put into a test tube and centrifuged was concentrated for 3 minutes at 14000 rpm. Subsequently, DNA was extracted using an assay kit, and U515f (5'-CTGYCAGCMGCCGCGGTAA-3', nucleic acid sequences at positions 515 to 533 in the E. coli sequence) and U1492r (5'-GGYTACCTTGTTACGACTT-3') were extracted through the literature. ', nucleic acid sequences from 1492 to 1510) PCR amplification was performed using primers. Microbial sequence analysis was performed using the Mothur program and RDP's Baysian Classifier, and the mimetic diagram of the microbial classification system was performed using the Mega program.

3 shows the results of microbial cloning analysis for each sample according to Example 1. Referring to FIG. 3, the total number of clones is 34-42, and it can be seen that they are generally classified into Proteobacteria , Bacterioidetes, Firmicutes , Cloacimonetes , Thermotogae , Euryarchaeota and other microbial groups. Among them, Proteobacteria are classified into Betaproteobacteia and Deltaproteobacteia , and Deltaproteobacteia are classified into Desulfuromonadaies and Syntrophobacterales . As a comparison group of experimental results, microbial community structure analysis was also performed on the inoculated sludge.

4 shows the number of microbial clones for each sample according to Example 1. Referring to FIG. 4 , it can be seen that, compared to the control sample, the microbial communities of Proteobacteria and Thermotogae increased in the sample 16 injected with activated carbon, and the community structure was relatively simple and concentrated. Similarly, it can be seen that the microbial populations of Proteobacteria and Thermotogae increased in samples containing glucose as a substrate and samples containing activated carbon. In addition, it can be seen that a large amount of Proteobacteria was detected in the sample (5G) with low pH and activated carbon.

5 shows the degree of distribution of each sample of Proteobacteria among microorganisms. Proteobacteria are divided into Gamma-, Beta-, Delta- and Alpha- proteobacteria , and among them, Beta- and Delta- proteobacteria appear to be dominant. Samples with activated carbon (16, 5G, GG) had more Delta-proteobacteria than the control group (C, 5N, GN) (except for 12G and 12N samples). In particular, Delta-proteobacteria were most frequently detected in 5G samples, and Beta- proteobacteria were most frequently detected in GN samples.

6 is a graph showing the number of clones of Geobacter species among Delta- proteobacteria for each sample. Referring to FIG. 6, Geobacter was detected only in all samples in which activated carbon was added. In particular, since the most species were detected in the cell where the pH was maintained as low as 5, Geobacter is known as a representative electrogenic microorganism and can provide electrons to the electrode through acetic acid oxidation. In addition, it has been reported that Geobacter can cooperate with other microorganisms that directly receive electrons through conductive cilia. In this regard, since activated carbon exhibits much higher conductivity than biological cilia, it is expected that the electron transfer mechanism between microorganisms can be further activated through activated carbon. As a result, when activated carbon is added, it can be determined that the methanogenesis inhibition phenomenon is alleviated through direct electron transfer despite the presence of the methanogenesis inhibitor in the substrate.

7 is Geobacter A taxonomic phylogenetic diagram of methane candidate bacteria capable of producing methane through a mechanism of directly receiving electrons through species and activated carbon is shown. Overall, Methanosarcina species and Methanosaeta It can be divided into species, and the difference according to whether or not activated carbon is injected is relatively insignificant. In the case of Methanosarcina species, it is reported that they can reduce carbon dioxide to methane by directly receiving electrons in addition to hydrogen and acetic acid, and it is judged that direct electron transfer is possible through Geobacter and activated carbon.

Example 3. batch Electroactivation in anaerobic digestion biomass increase

In order to determine whether electroactive biomass is dominant and active according to the input of activated carbon, oxidation and reduction reactions were investigated using a potentiometer. In particular, 20 mL of a bulk solution including biomass was injected into a separate 30 mL cell in a batch type methane generating cell into which activated carbon was introduced. At this time, after checking whether or not gas was generated in the batch type methane generating cell, the bulk solution was fractionated into a separate electrical test cell. The cell was configured in a single chamber type using three electrodes (two graphite electrodes were used as a working electrode and a counter electrode, respectively, and Ag/AaCl was used as a reference electrode). The current width generated while applying a voltage from 0.8 to -0.8 V (vs Ag/AgCl) using a potentiostat (potenstat) was recorded. At this time, the scan speed was 50 mV, and the upper space of the test cell was purged with nitrogen for 5 minutes before measuring the current.

8 shows a device for measuring oxidation and reduction reactions using a three-electrode cell to present evidence of the activity of electroactive microorganisms in a batch-type anaerobic digestion system.

Referring to FIG. 8, after confirming that biomass adhered to the surface of the working electrode, cyclic voltammograms (CV) were measured. After observing oxidation and reduction reactions in the presence of biomass, the electrode was separated and the biomass on the surface of the electrode was removed using distilled water. In addition, the reaction solution was filtered using a 0.45 μm filter to remove residual biomass. Oxidation and reduction peaks were measured while the electrode was reinstalled in an environment where biomass was removed and a voltage in the same range was applied.

On the other hand, Linear square voltammtry (LSV) was measured to examine the reduction reaction in detail while scanning the voltage in one direction. Specifically, 3 electrodes were installed on the top of a 500 mL double glass reactor, and a 20% (V/V) activated carbon layer and biomass were added to the bottom. The remaining part was filled with 300 mL of acetic acid-based substrate, the temperature was maintained at 35 °C, and the top of the reactor was purged with nitrogen for 5 minutes to create an anaerobic condition. Scans from -0.6 to 0.2 V to 50 mV for acetic acid oxidation and -0.8 to 0.6 V for carbon dioxide reduction were performed.

FIG. 9 is a diagram illustrating measurement results of CV and LSV measured using the apparatus shown in FIG. 8 . Referring to FIG. 9, the peak occurring around -0.4 V (as Ag/AgCl) is determined to be the result of the Geobacter species oxidizing acetic acid, whereas the peak occurring around 0 V is a previously unknown reaction. When the biomass was removed from the cell and from the electrode surface, the generated current width decreased and no peak was detected, suggesting that the biomass attached to the electrode surface was electroactive. In addition, a reduction peak generating a negative current was observed at around -0.4 V, which is judged to represent the activity of methane bacteria (reaction in which carbon dioxide is reduced to methane) that exhibits electroactivity.

In addition, looking at the LSV results, it can be seen that the positive and negative currents increase as the methanogenesis reaction proceeds. This indicates that oxidation and reduction reactions increased due to the formation and activity of an electroactive biofilm on the electrode surface as the reaction time elapsed.

Claims (15)

In the toxic wastewater treatment method based on anaerobic digestion,
Including; adding a conductive carrier to the anaerobic digestion tank into which the toxic wastewater flows,
The toxic wastewater contains a toxic substance selected from the group consisting of acetic acid, propionic acid, and mixtures thereof,
The concentration of the acetic acid per liter of the toxic wastewater is 4 g to 12 g, the concentration of the propionic acid is 0.5 g to 2.0 g,
The toxic wastewater has a pH of 5 to 7 and an ammonia concentration of 110 mg to 150 mg per liter of the toxic wastewater,
The conductive carrier is activated carbon,
Toxic wastewater treatment method based on anaerobic digestion, characterized in that the addition amount of the conductive carrier is 0.1 g to 0.4 g per 1 g of dry weight of the dry sludge in the toxic wastewater. delete According to claim 1,
The activated carbon is a toxic wastewater treatment method, characterized in that coal-based activated carbon or coconut-based activated carbon. According to claim 1,
Toxic wastewater treatment method, characterized in that the average particle diameter of the activated carbon is 0.8 mm to 2.2 mm. delete delete delete delete According to claim 1,
Toxic wastewater treatment method, characterized in that by the addition of the conductive carrier, microorganisms that build a mutual symbiotic relationship are attached to the surface of the conductive carrier. According to claim 9,
Toxic wastewater treatment method, characterized in that the microorganisms that establish the mutual symbiotic relationship are Geobacter species microorganisms and Methanosarcina genus microorganisms. According to claim 1,
A method for treating toxic wastewater, characterized in that methane gas is generated as biogas and electric current is generated. A digestion tank accommodating therein toxic wastewater and electroactive microorganisms that anaerobically digest the toxic wastewater;
a conductive carrier disposed inside the digester and to which the electroactive microorganism is attached to a surface thereof;
a working electrode to which, when a predetermined potential is applied, electron-generating microorganisms generating electrons by oxidizing toxic substances in the toxic wastewater among the electroactive microorganisms are attached;
a counter electrode to which electrons generated from the working electrode are introduced and to which electron-accepting microorganisms that receive the electrons from among the electroactive microorganisms and reduce carbon dioxide in the toxic wastewater to methane are attached;
a reference electrode maintaining a predetermined reference potential; and
A constant potential device that maintains the potential of the working electrode and the reference potential constant and measures the magnitude of the current in order to evaluate the degree of activity of the electroactive microorganisms proportional to the magnitude of the current, which is the flow of electrons. include,
The toxic wastewater contains a toxic substance selected from the group consisting of acetic acid, propionic acid, and mixtures thereof,
The concentration of the acetic acid per liter of the toxic wastewater is 4 g to 12 g, the concentration of the propionic acid is 0.5 g to 2.0 g,
The toxic wastewater has a pH of 5 to 7 and an ammonia concentration of 110 mg to 150 mg per liter of the toxic wastewater,
The conductive carrier is activated carbon,
The addition amount of the conductive carrier is 0.1 g to 0.4 g per 1 g of dry weight of the dry sludge in the toxic wastewater treatment device. According to claim 12,
Toxic wastewater treatment apparatus further comprising a purging unit for purging the inside of the digester. According to claim 12,
Toxic wastewater treatment apparatus further comprising an agitator disposed inside the digester and mixing the toxic wastewater and the electroactive microorganism. According to claim 12,
Toxic wastewater treatment apparatus, characterized in that the electron generating microorganism is a Geobacter species microorganism, and the electron accepting microorganism is a microorganism of the genus Methanosarcina .

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