KR102263401B1 - Cultibating and preparing method for anaerobic granule - Google Patents

Abstract

The present invention relates to a method for culturing and manufacturing anaerobic granules, and it is possible to manufacture anaerobic granules in which a conductive material is inserted at a high concentration. In addition, the performance of various biological processes as well as methane and hydrogen production using an anaerobic digestion process by inserting a conductive material into the inner and outer surfaces of the microbial mass including electron-donating microorganisms and electron-accepting microorganisms (methanogens, hydrogen-producing bacteria, etc.) It helps to improve. In addition, since it is possible to prevent loss due to external leakage of the conductive material, continuous injection of the conductive material is unnecessary, and stable process efficiency and economic feasibility can be secured even without a conductive material recovery facility after the reaction tank.

Description

CULTIBATING AND PREPARING METHOD FOR ANAEROBIC GRANULE

The present invention relates to a method for culturing and manufacturing anaerobic granules.

Anaerobic digestion (AD) can convert organic pollutants into useful energy carriers such as methane, and is considered as an alternative technology to cope with recent energy and environmental problems. Anaerobic digestion is widely applied in the treatment of high-concentration organic waste and wastewater, and is expected to play an important role in future energy safety and sustainability. Despite this potential, anaerobic digestion has several technical limitations due to its slow reaction rate.

These limitations include significantly longer retention times and lower rates of organic matter removal compared to aerobic treatment. Many efforts and attempts have been made to overcome these limitations and improve the effectiveness of anaerobic digestion techniques.

Recently, studies on the improvement of biogas conversion rate and production speed through Direct Interspecies Electron Transfer (DIET) have been reported. Conductive materials such as iron oxides are introduced to improve interspecies direct electron transfer between microorganisms in the anaerobic digestion process. It is known to promote and improve the biogasification efficiency.

However, since the conductive material is expensive, research on recovering it from the effluent for reuse is in progress, but it is very difficult to efficiently separate and recover the conductive material adsorbed to the solids present in the effluent.

Accordingly, it is necessary to develop a technology capable of securing the improved effect of the anaerobic digestion process efficiency for a long time without additional injection by preventing the external loss of the conductive material.

Korean Patent No. 1890721

An object of the present invention is to provide a method capable of directly inserting a conductive material at a high concentration into the interior and surface of a microbial granule.

An object of the present invention is to provide a method capable of promoting a direct electron transfer reaction between species.

An object of the present invention is to provide a wastewater treatment and energy production method that prevents loss of conductive material by inserting a conductive material such as magnetite into the microbial mass remaining at the lower end of the reactor and does not require a separate recovery process.

The present invention relates to an anaerobic microorganism in which a direct interspecies electron transfer (DIET) reaction occurs or a conductive material is injected into a reactor in which a microbial granule containing the anaerobic microorganism resides, and then ultrasonic is irradiated to the microorganism or It provides a method for culturing and manufacturing anaerobic granules comprising inserting the conductive material into the mass of the microorganism.

In the present invention, the anaerobic microorganisms may be electron-donating microorganisms and electron-accepting microorganisms.

In the present invention, the conductive material may be introduced into the reactor together with a substrate.

In the present invention, ultrasonic waves may be irradiated to the lower end of the reactor.

In the present invention, the substrate may include a microbial nutrient source selected from the group consisting of acetate, propionate, butyrate, ethanol, butanol and saccharides.

In the present invention, ultrasonic waves may be irradiated at 10 to 50 KHz and 50 to 400W for 0.1 to 10 seconds every minute.

In the present invention, the anaerobic microorganism is a microorganism of the genus Geobacter; It may include one or more selected from the group consisting of microorganisms of the genus Methanocytota, microorganisms of the genus Metanosarcina, microorganisms of the genus Methanospirillum, microorganisms of the genus Methanolina, microorganisms of the genus Clostridium, microorganisms of the genus Enterobacter and microorganisms of the genus Klebsiella have.

In the present invention, the conductive material may be any one selected from the group consisting of magnetite, hematite, activated carbon, graphene, and charcoal.

In the present invention, the substrate may be domestic sewage, livestock wastewater, dairy wastewater, food waste or food wastewater.

In the present invention, the conductive material may be present in the substrate in an amount of 0.01 to 1 g/L.

In the present invention, the conductive material may have a diameter of 10 μm or less.

The method for culturing and manufacturing anaerobic granules of the present invention enables the preparation of anaerobic granules in which a conductive material is inserted at a high concentration.

The method for culturing and manufacturing anaerobic granules of the present invention is an anaerobic digestion process by inserting a conductive material into the inner and outer surfaces of a microbial mass including electron-donating microorganisms and electron-accepting microorganisms (methanogens, hydrogen-producing bacteria, etc.). It helps to improve the performance of various biological processes as well as hydrogen production.

The method for culturing and manufacturing anaerobic granules of the present invention can prevent loss due to external leakage of the conductive material, so that continuous injection of the conductive material is unnecessary.

In the method for culturing and manufacturing anaerobic granules of the present invention, it is possible to secure stable process efficiency and economic feasibility even without a conductive material recovery facility after the reactor.

1 illustrates an interspecies direct electron transfer reaction between anaerobic microorganisms.
2 is a schematic diagram of a reactor in which the method of the present invention can be carried out.
3 is a simplified flowchart of a high concentration wastewater treatment process. Anaerobic granules can be cultured and prepared in the area indicated by the red circle.
4 is a reaction tank of Examples and Comparative Examples. 'Ultrasound' is an embodiment, and the part marked in red is an ultrasonic generator.
5 is a stereomicrograph of the anaerobic granules of Examples and Comparative Examples.
6 is a result of analysis of the magnetate component of the anaerobic granules using SEM / EDS of Examples and Comparative Examples.

The present invention relates to an anaerobic microorganism in which a direct interspecies electron transfer (DIET) reaction occurs or a conductive material is injected into a reactor in which a microbial granule containing the anaerobic microorganism resides, and then ultrasonic is irradiated to the microorganism or It provides a method for culturing and manufacturing anaerobic granules comprising inserting the conductive material into the mass of the microorganism.

Anaerobic microorganisms include electron-donating microorganisms and electron-accepting microorganisms in which electrons are transferred via conductive pili or electron transport proteins. A direct interspecies electron transfer reaction occurs between anaerobic microorganisms. 1 is a DIET reaction using magnetite.

When the conductive material is inserted into the microbial mass of the present invention, the DIET reaction is promoted. The microbial mass contains various types of microorganisms.

Electron-donating microorganisms refer to microorganisms that decompose organic matter to generate electrons and emit them to the outside. The electron-donating microorganism of the present invention is not limited to a specific type of microorganism. It includes microorganisms of the genus Geobacter, microorganisms of the genus Thauera or microorganisms of the genus Syntrophomonas. For example, Geobacter metallireducens or Thauera humireducens.

Electron-accepting microorganisms refer to microorganisms that generate biogas by using electrons emitted to the outside by the action of electron-donating microorganisms in a reduction reaction. The electron-accepting microorganism of the present invention is not limited to a specific type of microorganism. Depending on the type of biogas to be produced, it may be anaerobic methanogens, anaerobic hydrogen producers or anaerobic ammonia oxidizing homogeneous bacteria.

Electron-accepting microorganisms include microorganisms of the genus Methanosaeta, microorganisms of the genus Methanosarcina, microorganisms of the genus Methanospirillum, microorganisms of the genus methanolinea, microorganisms of the genus Clostridium, It includes microorganisms of the genus Enterobacter or microorganisms of the genus Klebsiella. For example, Methanosarcina bakeri, Methanosarcina harundinacea, or Methanosaeta concilii.

The microbial mass of the present invention may further include aerobic microorganisms. The microbial mass may be derived from sludge produced during the treatment of organic wastewater.

The conductive material of the present invention is a material capable of mediating or facilitating a direct interspecies electron transfer reaction between an electron-donating microorganism and an electron-accepting microorganism. When the conductive material is inserted into the microorganism, the anaerobic digestion process efficiency is improved, so biogas such as methane The production rate and production rate can be increased.

The conductive material may be any one selected from the group consisting of magnetite (Fe ₃ O ₄ ), hematite (Fe ₂ O ₃ ), activated carbon, graphene, and charcoal. Preferably it may be magnetite (Fe ₃ O ₄ ).

The conductive material has, for example, a diameter of 10 μm or less, 5 μm or less, 3 μm or less. In one embodiment, the diameter of the conductive material is between 0.1 and 3 μm.

The conductive material may be included in the substrate at 0.005 g/L to 2 g/L. In one embodiment, it may be included at 0.01 g/L to 1 g/L, and the conductive material may be included at a high concentration of 2 g/L depending on ultrasonic irradiation conditions and substrate.

The substrate of the present invention includes all kinds of waste liquids including organic matter. For example, it may include domestic sewage, livestock wastewater, dairy wastewater, food waste, food wastewater, etc., but is not limited thereto.

In the present invention, the substrate may comprise a mixture of sludge and wastewater. The sludge may contain organic sludge, microorganisms and some inorganic matter, and in some cases only organic sludge. The sludge may be collected from an organic waste digester that treats conventionally obtained municipal sewage, livestock wastewater, dairy wastewater, etc., but is not limited thereto. In one embodiment of the present invention, the substrate may include sludge produced in an anaerobic digestion process.

The substrate may further include a substance capable of promoting the growth of microorganisms or promoting a direct interspecies transfer reaction. As a nutrient source for microorganisms, it may include any one selected from the group consisting of acetate, propionate, butyrate, ethanol, butanol, and saccharides.

According to the present invention, when a conductive material is injected into a reaction tank in which microorganisms or microbial masses reside and then irradiated with ultrasonic waves, the conductive material is inserted into the microbial mass. A conductive material is attached to the surface of the microorganism and the surface of the microbial mass. When a conductive material is attached to the surface of the microbial mass and then the microbial mass grows due to aggregation between microorganisms, the conductive material may be inserted into the microbial mass.

As an acoustic wave generated during ultrasonic irradiation is transmitted to the microbial mass in the reaction tank, fluidity increases, so that the conductive material can be better attached or inserted into the surface and inside of the microbial mass. Accordingly, the conductive material may be included in a high concentration in the microbial mass.

Since the anaerobic granules obtained according to the method of the present invention contain a conductive material in a high concentration, the direct interspecies transfer reaction of microorganisms can be further promoted.

Ultrasound may be irradiated for 0.1 to 10 seconds every minute at 10 to 50 KHz, 50 to 400W. When the ultrasonic irradiation range is as above, the concentration of the conductive material included in the microbial mass can be effectively increased.

Ultrasound may be irradiated with a frequency of 10 to 50 KHz, and may be irradiated with a frequency of 25 to 35 KHz.

Ultrasound may be irradiated with an output of 50 to 400W, and may be irradiated with an output of 150 to 300W.

The ultrasonic irradiation time may be 0.1 seconds to 10 seconds every 0.5 to 3 minutes, and may be 0.5 seconds to 1.5 seconds every 0.5 to 1.5 minutes.

The ultrasonic waves are preferably irradiated toward the microbial mass when it is adjacent within a distance where the conductive material can be attached or inserted.

For example, when the microbial mass is located in the lower portion of the reaction tank, the ultrasonic wave may be irradiated when the conductive material is introduced into the lower portion of the reaction tank.

For example, as shown in Figure 2, when the substrate flows into the lower end of the reactor and flows out to the upper end, the ultrasonic generator is located at the lower end of the reactor and before the conductive material passes through the microbial mass according to the flow of the substrate, it is preferably located at the bottom of the microbial mass. Or it is better to irradiate the ultrasound at the moment it passes through the microbial mass.

The reactor of the present invention may be a microbial reactor such as an incubator or an anaerobic digestion reactor. The method of the present invention may be performed, for example, in one of Upflow Anaerobic Sludge Blanket (UASB), Continuously-Stirred Tank Reactors (CSTRs) and Expanded Granular Sludge Bed (EGBS).

According to an embodiment of the present invention, when the organic waste liquid (substrate) is continuously introduced into the reaction tank, the organic waste liquid is introduced into the reaction tank including granules (microorganisms). The organic waste liquid flows in from the lower side and flows out through the granules to the upper side. At this time, since the granules stay in the lower part of the organic waste liquid, specifically, the lower part of the reaction tank due to the difference in density, the granules do not flow out even when the organic waste liquid flows in from the lower side of the reaction tank and flows through the granules to the upper side. Since the granules do not leak out, the inserted conductive material does not leak out either.

The conductive material may be introduced in addition to the substrate or may be introduced separately. When the conductive material is introduced separately, the conductive material may be introduced from the lower side of the reaction tank, and when the conductive material is located under the microbial mass, ultrasonic waves may be irradiated to the lower side of the reaction tank.

Cultivation and production of the anaerobic granules of the present invention may be performed in one or more treatment steps of a wastewater treatment process.

For example, in the case of a high-concentration organic wastewater treatment process, after the step of removing the solids (crop) of the high-concentration wastewater that has entered the treatment facility, if the wastewater is injected into the anaerobic digestion reactor, anaerobic digestion proceeds by the anaerobic granules according to the method of the present invention do. Thereafter, an additional step of removing nitrogen, phosphorus, and the like may be performed.

In addition, when the anaerobic digestion step in the wastewater treatment process is carried out separately in the acid fermentation reactor and the methane fermentation tank, the culturing and manufacturing of the anaerobic granules according to the present invention and the anaerobic digestion step in each reaction tank may be performed together (FIG. 3). .

Examples and Comparative Examples

Anaerobic seeding sludge was inoculated into the UASB reactor used for the anaerobic digestion process with the ultrasonic generator installed at the bottom, and the magnetite (Sigma-Aldrich, particle size less than 5㎛) was 0.1 at an upflow of 1.5m/h at 38°C. While injecting the glucose solution added at a concentration of g/L, the reactor was operated for a week while simultaneously irradiating ultrasonic waves of 200 W output at a frequency of 28 kHz for 1 second per minute (FIG. 4, ultrasonic waves).

In Comparative Example, the reactor operation was performed in the same manner as in the above example except that ultrasonic wave was not irradiated ( FIG. 4 , control).

Confirmation of presence and concentration of magnetite in Examples and Comparative Examples

After the operation of the reaction tanks of Examples and Comparative Examples was completed, granules were collected from each reaction tank and observed with a stereoscopic microscope (FIG. 5). It was confirmed whether the component of magnetite in the granules was present using SEM-EDS (FIG. 6).

In addition, the concentration of magnetite in each granule of Examples and Comparative Examples was measured using the Ferozine method (ferrozine method), and the results are shown in Table 1 below.

division Primary measurement (mg/g) Secondary measurement (mg/g) result Control Reactor (1 week) 10.616 10.460 10.538±0.110 Ultrasonic Reactor (1 week) 18.591 18.496 18.543±0.067

According to Table 1, it was confirmed that the example contained magnetite at a concentration about 80% higher than that of the comparative example.

According to FIG. 5, since the anaerobic granule surface of the Example showed more black parts, it was confirmed that more magnetite was inserted in the Example irradiated with ultrasound compared to the Comparative Example in which it was not.

As shown in FIG. 6 , it was confirmed that the ultrasonically irradiated Example was more evenly distributed than the Comparative Example of the magnetite on the surface of the anaerobic granules.

Claims (11)

After injecting a conductive material from the lower part of the reactor into the reactor in which the microbial granules containing the anaerobic microorganisms in which the Direct Interspecies Electron Transfer (DIET) reaction occurs, the conductive material is injected from the bottom of the reactor, and then the substrate flows to the upper part of the reactor The method for culturing and manufacturing anaerobic granules, comprising the step of inserting the conductive material into the microbial mass by irradiating ultrasonic waves at the moment when the conductive material is positioned below the microbial mass or passes through the microbial mass.
The method according to claim 1, wherein the anaerobic microorganisms are electron-donating microorganisms and electron-accepting microorganisms.
The method for culturing and manufacturing anaerobic granules according to claim 1, wherein the conductive material is introduced into the reactor together with a substrate.
The method according to claim 1, wherein the ultrasonic wave will be irradiated to the lower end of the reaction tank, anaerobic granules culture and manufacturing method.
The method according to claim 3, wherein the substrate comprises a microbial nutrient source selected from the group consisting of acetate, propionate, butyrate, ethanol, butanol and saccharides.
The method for culturing and manufacturing anaerobic granules according to claim 1, wherein the ultrasonic waves are irradiated for 0.1 to 10 seconds every minute at 10 to 50 KHz, 50 to 400W.
The method according to claim 1, wherein the anaerobic microorganism is a microorganism of the genus Geobacter; Including one or more selected from the group consisting of microorganisms of the genus Methanocytota, Methanosarcina microbes, Methanospirillum microbes, Metanolinea microbes, Clostridium microbes, Enterobacter microbes and Klebsiella microbes, Methods for culturing and preparing anaerobic granules.
The method according to claim 1, wherein the conductive material is any one selected from the group consisting of magnetite, hematite, activated carbon, graphene and charcoal.
The method according to claim 3, wherein the substrate is domestic sewage, livestock wastewater, dairy wastewater, food waste or food wastewater.
The method for culturing and manufacturing anaerobic granules according to claim 3, wherein the conductive material is present in the substrate in an amount of 0.01 to 1 g/L.
The method for culturing and manufacturing anaerobic granules according to claim 1, wherein the conductive material has a diameter of 10 μm or less.

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