KR100960596B1 - Method and apparatus for Bio-hydrogen gas production from organic waste by using inhibitor for methane producing microorganisms and gas purging - Google Patents

Abstract

The present invention discloses an apparatus and method for producing hydrogen from organics present in organic waste using anaerobic fermentation microorganisms. Specifically, by minimizing the consumption of hydrogen by the methane-producing microorganisms by injecting the inhibitor of the methane-producing microorganisms, by lowering the partial pressure of hydrogen by intermittent gas purge, to increase the activity of the hydrogen-producing microorganisms to produce hydrogen in high yield An apparatus and method are disclosed. Using the bio-hydrogen gas production method according to an embodiment of the present invention, it is possible to produce hydrogen with economical, stable and high efficiency, compared to the conventional method for producing bio-hydrogen gas from organic wastes, in particular, the continuous gas purging process It is possible to produce highly efficient and stable bio-hydrogen gas even through intermittent gas purging. In addition, it is easy to commercialize by combining the bio-hydrogen gas production method in a unit process.

Organic waste recycling, bio-hydrogen production, methane activity inhibition, inhibitors, gas purging, anaerobic fermentation

Description

Method and apparatus for Bio-hydrogen gas production from organic waste by using inhibitor for methane producing microorganisms and gas purging

The present invention relates to an apparatus and method for producing hydrogen from organics present in organic waste using anaerobic fermentation microorganisms. Specifically, by minimizing the consumption of hydrogen by the methane-producing microorganisms by injecting the inhibitor of the methane-producing microorganisms, by lowering the partial pressure of hydrogen by intermittent gas purge, to increase the activity of the hydrogen-producing microorganisms to produce hydrogen in high yield It relates to an apparatus and a method.

At present, more than 96% of hydrogen is produced from fossil fuels, and it is not an environmentally friendly method due to the limited reserves of coal and oil and the emission of environmental pollutants. Recently, there is a growing interest in biological hydrogen production methods for producing hydrogen from organic waste using microorganisms. As marine emission regulations on organic waste have been strengthened, it is necessary to treat and recycle the organic waste, which has been mostly disposed of in marine discharges, landfills, and incineration.

Since biological hydrogen production is performed at room temperature and atmospheric pressure, it consumes less energy, and since hydrogen is produced from renewable waste resources, it has advantages in two aspects: reducing environmental pollution and producing clean alternative energy. In the case of hydrogen, the energy content per unit mass is 120 MJ / kg and other energy sources (coal 30 MJ / kg, natural gas 50 MJ / kg, petroleum 45 MJ / kg, diesel 43 MJ / kg, ethanol 21 MJ / kg) It is much higher than), which is more effective in bioenergy production.

In general, the gases produced under anaerobic conditions are hydrogen and methane, but hydrogen is methane because of low production efficiency and conversion to methane by hydrogen-utilizing methanogens. It is true that it has received less attention. However, when methane gas produced by microorganisms is used as energy, the final product is carbon dioxide (CO ₂ ), which is the main culprit of global warming, whereas in the case of hydrogen gas, the final product is water vapor, so it is not suitable for use as an eco-friendly renewable energy. It is possible. For this reason, hydrogen energy is in the limelight as the most promising alternative of future clean energy sources.

In the case of biohydrogen production research conducted at home and abroad, most of them are focused on hydrogen production by photosynthetic microorganisms or algae using solar energy. Although many basic studies on hydrogen production by anaerobic fermentation have been attempted, low hydrogen production yields have been pointed out as problems compared to other biological hydrogen production processes. However, biohydrogen production by anaerobic fermentation is faster than hydrogen production by photosynthetic microorganisms, 1) faster hydrogen production rate, 2) hydrogen production occurs under no light conditions, and therefore hydrogen production is possible without time constraints. Due to the growth speed, the facility has been evaluated as a suitable technology for mass production of hydrogen due to advantages such as the large size of the facility and the convenience of maintenance.

The most widely used method for increasing bio-hydrogen production is to lower the activity of methane-producing microorganisms, and pH control, heat treatment at high temperature, and pretreatment through aeration have been attempted, but yields of hydrogen are extremely low.

When the microorganism produces hydrogen gas under anaerobic conditions, if the hydrogen partial pressure rises above a certain level due to build of hydrogen in the reactor, the microorganism stops producing hydrogen. In addition, when hydrogen gas is present in the reactor for a certain time, hydrogen is converted into methane gas by the methane generating microorganism.

In order to overcome the limitations of existing low-yield biohydrogen production technology, the present invention minimizes the consumption of hydrogen by methane-producing microorganisms by injecting inhibitors to suppress the activity of methane-producing microorganisms and by intermittent gas purging. It is an object of the present invention to provide a method for increasing bio-hydrogen production by lowering the partial pressure to increase the activity of hydrogen-producing microorganisms and an apparatus used therefor.

The present invention is a bio-hydrogen gas production reactor (1); An organic waste storage tank 2 connected to the bio-hydrogen gas production reactor; A methane-producing microbial activity inhibitor storage tank 3 connected on a line to which the bio-hydrogen gas production reactor and the organic waste storage tank are connected; A gas tank 11 connected to a lower portion of the bio-hydrogen gas production reactor; And a hydrogen gas separation device 8 connected to the upper portion of the bio-hydrogen gas production reactor.

The present invention also provides a method for producing bio-hydrogen gas from the organic waste, comprising the steps of injecting the organic waste into the reactor; Injecting a methane producing microbial activity inhibitor into the reactor; Injecting gas into the organic waste in the reactor to lower the partial pressure of hydrogen in the reactor; And it provides a bio-hydrogen gas production method comprising the step of separating and recovering hydrogen gas in the generated gas.

Using the bio-hydrogen gas production method according to an embodiment of the present invention, it is possible to produce hydrogen with economical, stable and high efficiency, compared to the conventional method for producing bio-hydrogen gas from organic wastes, in particular, the continuous gas purging process It is possible to produce highly efficient and stable bio-hydrogen gas even through intermittent gas purging. In addition, it is easy to commercialize by combining the bio-hydrogen gas production method in a unit process.

Hereinafter, a method for producing biohydrogen gas from the organic waste according to the present invention will be described in detail.

In order to produce biohydrogen gas with the method according to the invention, the apparatus shown in FIG. 1 can be used. 1 is a schematic diagram of an apparatus for producing biohydrogen gas according to the present invention from organic waste. Using the apparatus, it is easy to commercialize the system by combining the biohydrogen gas production method according to the present invention in a unit process.

The method for producing biohydrogen gas from the organic waste according to the present invention,

(1) organic waste injection process,

(2) methane generating microbial activity inhibitor injection process,

(3) a gas purging process for lowering the partial pressure of hydrogen in the reactor,

(4) separating and recovering the generated hydrogen gas and measuring the recovered amount of hydrogen gas.

According to one embodiment of the invention, the method of producing bio-hydrogen gas from organic waste can be carried out using the apparatus of FIG.

First, the organic waste stored in the organic waste storage tank 2 is injected into the bio-hydrogen gas production reactor 1 using the metering pump 15. At this time, the methane-producing microbial activity inhibitor stored in the methane-producing microbial activity inhibitor storage tank (3) is injected into the bio-hydrogen gas production reactor (1) using a metering pump (16). The anaerobic fermentation reaction takes place in the reactor in which the temperature is maintained by the reactor temperature controller 4, and the external gas stored in the gas tank 11 passes through the gas flow controller 12 to the gas diffusion device. Through (14), it is purged with the organic waste (liquid) in a reaction tank. The effluent flows out of the reactor via the effluent line 6 and the metering pump 17, and the produced gas is discharged through the gas discharge line 7 and introduced into the hydrogen gas separator 8. The separated hydrogen gas amount is measured by the hydrogen gas amount measuring device 9, and gases other than hydrogen gas are conveyed to the reaction tank via the gas flow line 10 through the gas flow regulator 13 and used for purging.

According to one embodiment of the present invention, the organic waste injected in the step (1) is any sludge, wastewater treatment plant generated sludge, digester supernatant and desorption liquid, livestock wastewater and waste, agriculture and forestry wastewater and waste, fishery wastewater and waste, etc. Organic wastewater and waste types can be used.

The microorganisms used for hydrogen production are preferably anaerobic digested sludge obtained from anaerobic digesters in sewage treatment plants rather than pure cultures. It is good to pass the screening before injection.

According to one embodiment of the present invention, the inhibitor injected in the step (2) is 2-bromoethanesulfonic acid (2) which is a similar compound of coenzyme-M, which controls the step of producing methane in methane producing microorganisms (2). -bromoethanesulfonic acid (BESA) is preferred. When injecting BESA as an inhibitor, the applicable concentration range is 0.2 to 30 g / L. If the concentration of BESA is less than 0.2g / L there is no inhibitory effect, when the concentration of more than 30 g / L there is no increase in effect due to the increase in the injection amount. Molybdate, azide, aminobenzoic acid or anthraquinone, which are known as other methane-producing microbial inhibitors, are also applicable. However, this is only an example presented to aid the understanding of the present invention, but is not limited thereto.

According to one embodiment of the present invention, since the gas injected in the step (3) may induce the suppression of the activity of the hydrogen-producing microorganisms when oxygen is included, it is preferable to inject a gas containing no oxygen. Applicable gases include inert gases (helium, nitrogen, argon, carbon dioxide, methane, etc.), and the injection flow rate can be applied from 100 to 10,000 mL / min, but the gas injection flow rate is increased to significantly lower the hydrogen partial pressure and increase the yield of hydrogen production. The more, the more effective.

According to one embodiment of the present invention, it is preferable to use a separation membrane for selectively separating only hydrogen gas as a step for effectively separating and recovering the bio-hydrogen gas generated in the reaction tank in the step (4). However, this is only to be provided to aid the understanding of the present invention, but is not limited thereto. Carbon dioxide, methane, etc. present after hydrogen separation among the gases generated in the reactor can be returned and used as a purging gas.

In order to continuously purge the gas to lower the partial pressure of hydrogen, a large amount of external gas must be injected continuously, which is expensive due to external gas injection. In addition, when the generated hydrogen gas is separated, the amount of external gas injected is higher than that of the generated gas, and thus, the separation cost is also high.

Hereinafter, the content of the present invention will be described in more detail by the test examples. However, these test examples are only presented to aid the understanding of the present invention, and the scope of the present invention is not limited to these test examples.

< Test Example  1: Measurement of the Effect of Injecting Methanogenic Microbial Activity Inhibitors>

Digested sludge from the anaerobic digester of Jungnang Sewage Treatment Plant in Seoul was planted and injected into the reactor. The reaction temperature was 35 ° C., the stirring speed was 160 rpm, and the volume of the reactor was 500 mL. Digested sludge was the only carbon source injected, with a concentration of 2,000 mgCOD / L.

Table 1 shows the methane gas content and the methane gas production yield in the generated gas. The yield of methane gas is calculated by accumulating the amount of methane gas produced by the microorganisms of the injected digested sludge, measuring the amount of organic matter removed by chemical oxygen demand (COD), and then generating "methane generated" for "COD removed organic matter." The COD value of the gas "is calculated in% and is expressed as the production yield.

Inhibitors of methane-producing microorganisms were injected with BESA (2-bromoethanesulfonic acid) at 0, 1, 10 and 25 g / L, respectively, to compare the deactivation of methane-producing microorganisms according to the amount of inhibitor injection. The total driving period was 85 days. The amount of gas generated was measured using a water displacement apparatus, and the methane gas content was measured using gas chromatography (GC-TCD).

When BESA was injected as an active inhibitor of methane-producing microorganisms, it was shown that as the amount of BESA injection increased, both the methane content in the generated gas and the yield of methane gas production from the injected organic waste were lowered. In particular, when BESA injection more than 10 g / L concentration showed a significantly lower methane gas production yield, it was confirmed that BESA has the effect of inhibiting the activity of methane-producing microorganisms.

However, in all reactors, the yield of hydrogen gas from organic waste is less than 0.8%, and it seems that there is a limit to increasing the yield of bio-hydrogen only by injection of methane activator.

BESA injection volume (g / L) Methane Gas Content (%) Methane gas production yield (%) 0 72.2 77.8 One 65.2 57.4 10 22.6 10.6 25 18.6 8.3

< Test Example  2: gas Fuzzing  Effect Measurement>

Digested sludge was planted under the same conditions as in Test Example 1 and injected into the reactor. In order to examine the effect of increasing the hydrogen production yield by intermittent gas purging, the hydrogen production yield was compared by gas purging the headspace of the reactor (empty space in the reactor) and the organic waste (liquid) in the reactor without introducing an inhibitor. The gas injected for gas purging was argon and gas purging was performed once a day for 15 minutes. The total driving period was 10 days.

Table 2 shows the biogas production yield of organic waste sludge according to gas purging conditions. The yield of biogas production was expressed by calculating the "COD of generated biogas" in% compared to "COD of removed waste sludge".

Decreased activity of methane-producing microorganisms due to intermittent gas purging was not observed in the case of purging the headspace (empty space in the reactor), and in the case of purging the organic waste (liquid) in the reactor, the lower the methane gas as the purging rate increased. Production yield was confirmed. Therefore, when gas purging the organic waste (liquid) in the reactor was able to confirm the degradation of the methane-producing microorganisms. However, the yield of hydrogen gas produced from waste sludge by intermittent gas purging is up to 0.42%, and as in Test Example 1, it was found that there is a limit to increasing the yield of bio-hydrogen by gas purging alone.

Gas purging conditions Methane Gas Yield (%) Hydrogen gas yield (%) Headspace, 2 L / min 70.7 0.05 Organic waste in the reactor, 1 L / min 64.0 0.22 Organic waste in the reactor, 2 L / min 47.6 0.42

< Test Example  3: injection and gas of methanogenic microbial activity inhibitor Fuzzing  Check the effect>

Digested sludge was planted under the same conditions as in Test Examples 1 and 2 and injected into the reactor. In order to confirm the effect of increasing the yield of hydrogen produced by the injection of inhibitors and the intermittent gas purging to reduce the activity of methane-producing microorganisms, various gas purging conditions were performed after reducing the activity of the methane-producing microorganisms by injecting 10 g / L of BESA into all reactors. Biohydrogen production yields were compared. As in Test Example 2, the gas injected for gas purging was argon, and gas purging was performed once a day for 15 minutes. The total driving period was 10 days.

Table 3 shows the yield of biogas production of organic wastes according to gas purging conditions when the methane generating microbial inhibitor is injected. As in Test Examples 1 and 2, the biogas production yield was expressed by calculating "COD of generated biogas" in% compared to "COD of removed waste sludge".

Gas purging conditions
(BESA 10 g / L injection) Methane gas production yield (%) Hydrogen gas production yield (%) Headspace, 2 L / min 42.26 1.08 Organic waste in the reactor, 1 L / min 15.32 4.19 Organic waste in the reactor, 2 L / min 4.08 7.12

As can be seen from Table 3, high bio-hydrogen gas production yield (up to 7.1%) when methane activity inhibitor is injected and gas purging at the same time to discharge hydrogen gas generated in the reactor to lower the partial pressure of hydrogen to increase the activity of hydrogen-producing microorganisms. ) However, gas purging of the headspace in the reactor resulted in a relatively lower yield of hydrogen gas production than gas purging of the organic waste (liquid) in the reactor, in which the hydrogen generated by the hydrogen-producing microorganisms produced organic waste (liquid) in the reactor. ), A significant amount is converted to methane by hydrogen-producing methane-producing microorganisms.

Therefore, in order to increase the yield of bio-hydrogen gas from organic wastes, it was confirmed that a methane generating microbial activity inhibitor should be injected, and at the same time, a method of maintaining a low hydrogen partial pressure by gas purging the organic waste (liquid) in the reaction tank in the reactor was effective. In addition, as the gas purging rate was increased, a higher hydrogen gas production yield was confirmed, and as the gas purging frequency, time, and purging rate were increased, a higher hydrogen gas production yield was found.

1 is a schematic diagram of an apparatus for producing biohydrogen gas from organic waste according to one embodiment of the present invention.

<Description of main parts of drawing>

1: Bio-hydrogen gas production reactor

2: organic waste storage tank

3: methane generating microbial activity inhibitor reservoir

4: reactor temperature controller

5: stirrer

6: effluent line

7: gas discharge line

8: hydrogen gas separation device

9: hydrogen gas amount measuring device

10: gas return line

11: gas tank

12,13: gas flow regulator

14: gas diffusion device

15,16,17: Metering pump

Claims (13)

A biohydrogen gas production reactor (1) in which anaerobic hydrogen-producing microorganisms for fermenting organic waste and hydrogen-utilizing methanogens are present; An organic waste storage tank 2 supplied to the reaction tank 1; A storage tank (3) of methane-producing microbial activity inhibitor injected to prevent hydrogen consumption by the hydrogen-producing methane-producing microorganism; A gas tank (11) storing an inert gas supplied to lower the partial pressure of hydrogen in the reactor (1); And Bio-hydrogen production apparatus comprising a hydrogen gas separation device (8) connected to the upper portion of the reactor (1). The method of claim 1, wherein the device, And a gas transfer line (10) connecting the hydrogen gas separation device and the lower part of the bio-hydrogen gas production reactor. The apparatus of claim 1 or 2, wherein the apparatus comprises: And a gas diffusion device (14) at a portion where the gas tank (11) or the gas transfer line (10) is connected to a lower portion of the biohydrogen gas production reactor. The biohydrogen production apparatus of claim 3, wherein the gas diffusion device is a porous acid stone, a membrane, a tubing, or an diffuser. The biohydrogen production apparatus of claim 1, wherein the hydrogen gas separation device comprises a gas separation membrane capable of separating hydrogen gas. As a method of producing biohydrogen gas from organic waste, Injecting organic waste into the reactor; Fermenting the organic waste through anaerobic hydrogen generating microorganisms; In order to prevent hydrogen from being consumed by hydrogen-utilizing methanogens contained in the reactor together with anaerobic hydrogen-producing microorganisms Injecting a methane producing microbial activity inhibitor into the reactor; Injecting an inert gas into the reactor to lower the partial pressure of hydrogen in the reactor; And Biohydrogen gas production method comprising the step of separating and recovering hydrogen gas in the produced gas. The method of claim 6, wherein the organic waste is sewage and wastewater treatment plant-generated sludge, digester supernatant and leachate, livestock wastewater and waste, agriculture and forestry wastewater and waste, or fishery wastewater and waste. The method of claim 6, wherein the methane-producing microbial activity inhibitor is 2-bromoethanesulfonic acid (BESA), molybdate, azide, aminobenzoic acid or anthraquinone (anthraquinone) biohydrogen gas production method. The method of claim 8, wherein the BESA is injected at a concentration of 0.2 to 30 g / L. The method of claim 6, wherein the gas injected to lower the partial pressure of hydrogen is an inert gas containing 0 to 5% of oxygen by volume. The method of claim 10, wherein the inert gas is helium, nitrogen, argon, carbon dioxide, or methane. The method of claim 6, wherein the gas injected to lower the partial pressure of hydrogen is injected at a flow rate of 100 to 10,000 mL / min. The bio-hydrogen gas production method according to claim 6, further comprising a step of returning hydrogen gas from the gas generated in the reaction tank after the separation of the hydrogen gas, into the reaction tank to lower the partial pressure of hydrogen in the reaction tank.

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