KR100446070B1 - Apparatus and method for removal of bad smell and volatile organic compounds - Google Patents

Abstract

The present invention relates to an apparatus and a method for removing malodors and volatile organic compounds (VOCs) using microorganisms, wherein the malodor and VOC removing apparatus according to the present invention includes odors and VOC-containing gas inside a hydrophobic hollow fiber membrane. A bioreactor having a hydrophobic hollow fiber membrane bundle composed of a plurality of hydrophobic hollow fiber membranes so as to dissolve odors and VOCs into a microbial layer surrounding the hydrophobic hollow fiber membranes when passing through the microbial culture medium; A gas inlet provided at an upper end of the bioreactor to be connected to an upstream end of the bundle of hydrophobic hollow fiber membranes deposited in the microbial culture medium so that gas containing malodor and VOC is introduced into the hydrophobic hollow fiber membrane; And it is connected to the lower end of the hydrophobic hollow fiber membrane bundle deposited in the microbial culture medium characterized in that it comprises a gas discharge portion provided at the bottom of the bioreactor to discharge the gas passing through the hydrophobic hollow fiber membrane. When using the odor and VOC removal apparatus and the removal method according to the present invention, the odor and VOC removal efficiency is maintained for a long time, and the odor and VOC is removed in a stable and high efficiency even in the concentration load and flow rate variation. In addition, the cost of media replacement and cleaning is small.

Description

Apparatus and method for removal of bad smell and volatile organic compounds}

The present invention relates to an apparatus and method for removing odors and volatile organic compounds (VOCs) discharged from various industrial facilities by using microorganisms.

Odors and VOCs contained in polluting gases emitted from various industrial facilities and environmental infrastructures cause various air pollution. Typical odorous substances include sulfide-based odorous substances such as hydrogen sulfide and methyl mercaptan, and nitrogen-based amines such as ammonia and amines. The main components of VOC are organic acids, aldehydes, ketones, and aromatic compounds.

Various methods have been attempted to remove odors and VOCs. In the past, various methods used to remove odors and VOCs include various physicochemical methods such as activated carbon adsorption, chemical liquid cleaning, catalytic oxidation, and high temperature incineration. . However, when odors and VOCs are removed using the physicochemical treatment method, secondary pollutants (SO _x , CO, NO _x ) are discharged, and facility costs and operation costs are high. Therefore, in recent years, the method using the biodegradation of microorganisms has been used a lot.

The principle of eliminating odors and VOCs using microorganisms is that microorganism layers (biofilms) are formed on microbial carriers, and microorganisms pass malodors and VOCs through a fixed carrier, thereby causing malodors and To break down the VOC. Compared with the physicochemical method, such a method using microorganisms has excellent economical efficiency because of less burden of facility cost and operation cost, low energy consumption rate, and low chemical and fuel consumption. In addition, there is an advantage that there is no secondary pollutant because the odor and VOC is finally decomposed into water and carbon dioxide.

However, in the carrier filling type device as described above, due to the clogging phenomenon in which the biofilm propagated with the passage of operating time blocks the pores between the carrier particles, not only the treatment flow rate is reduced but also a high pressure loss is caused, resulting in contamination. There is a problem that the treatment efficiency of the material is reduced and the power consumption rate is increased. As a result, in order to recover the treatment rate, it is necessary to periodically stir / wash or replace the carrier in order to detach the excessively formed biofilm, thereby avoiding a problem of high cost.

In addition, since there is a limit in the range of the amount and concentration of contaminants that can be treated by the microorganisms attached to the carrier, there is a problem that the contaminants cannot be treated with high efficiency and stable at high concentration load and flow rate variation.

Therefore, there was a need to improve the disadvantages of the prior art as described above.

The present invention is to solve the problems of the prior art as described above, to maintain the odor and VOC removal efficiency for a long time, and provides a device and method that can remove the odor and VOC with stable and high efficiency even in the concentration load and flow rate variation The purpose is to.

It is another object of the present invention to provide an apparatus and a method capable of removing odor and VOC removal which are inexpensive and easy to manage.

Figure 1 schematically shows an embodiment of the device for removing odor and volatile organic compounds (VOC) provided by the present invention.

* Description of the symbols for the main parts of the drawings *

1: microbial culture medium 2: bundle of hollow fiber membrane

3: bioreactor 4: upward end of hollow fiber membrane bundle

5: injection pump 6: pressure gauge

7: Downward end of the bundle of hollow fiber membranes 8: Nutrient supply tank

9: peristaltic pump 10: hood

11: flow meter 12: circulation pump

13: Injection pump 14: Drying part

SP: sample point

In order to achieve the above object, the device for removing odor and VOC according to the present invention,

A bioreactor having a hydrophobic hollow fiber membrane bundle composed of a plurality of hydrophobic hollow fiber membranes so as to dissolve odors and VOCs into a microbial layer surrounding the hydrophobic hollow fiber membrane when the malodorous and VOC-containing gas passes through the hydrophobic hollow fiber membrane; A gas inlet provided at an upper end of the bioreactor to be connected to an upstream end of the bundle of hydrophobic hollow fiber membranes deposited in the microbial culture medium so that gas containing malodor and VOC is introduced into the hydrophobic hollow fiber membrane; And it is connected to the lower end of the hydrophobic hollow fiber membrane bundle deposited in the microbial culture medium characterized in that it comprises a gas discharge portion provided at the bottom of the bioreactor to discharge the gas passing through the hydrophobic hollow fiber membrane.

In the malodor and VOC removing apparatus according to the present invention, the malodor and VOC removing apparatus further comprises a nutrient substance supply tank for supplying nutrients to the growth of microorganisms growing in the microbial culture medium outside the microbial reaction tank. It features.

In the malodor and VOC removing apparatus according to the present invention, the malodor and VOC removing apparatus compresses the gas flowing into the hydrophobic hollow fiber membrane to a pressure within a certain range so that liquid outside the hydrophobic hollow fiber membrane does not penetrate into the hydrophobic hollow fiber membrane It characterized in that it further comprises a compression unit to the outside of the microbial reaction tank.

In the malodor and VOC removing apparatus according to the present invention, the malodor and VOC removing apparatus is mixed with the microbial culture solution in the bioreactor so that the thickness of the microbial layer grown by attaching to the outside of the hydrophobic hollow fiber membrane is mixed with nutrients. It characterized in that it further comprises a circulation pump for smoothly delivering to the outside of the microbial reactor.

In the odor and VOC removal apparatus according to the present invention, the bioreactor is characterized in that the lower end is concave so that the dead microbial flocs falling off the surface of the hydrophobic hollow fiber membrane is precipitated and can be easily removed.

In addition, in order to achieve the above object, the method for removing odor and VOC according to the present invention,

(A) forming a biofilm on the surface of the hydrophobic hollow fiber membrane by depositing a plurality of hydrophobic hollow fiber membrane bundles in a microbial culture inoculated with microorganisms capable of decomposing bad smell and VOC; Odor and VOC-containing gas through the gas inlet provided at the top of the bioreactor including the microbial culture medium and the hydrophobic hollow fiber membrane bundle deposited in the culture medium, in the step (a) upstream of the hydrophobic hollow fiber membrane bundle (B) introducing a; (C) biodegradation of odor and VOC by the biofilm on the surface of the hydrophobic hollow fiber membrane while the gas introduced to the upper end of the hydrophobic hollow fiber membrane bundle in the step (b) passes through the hydrophobic hollow fiber membrane bundle; And (d) discharging the gas from which the odor and the VOC are decomposed in the step (c) through the downward end of the hydrophobic hollow fiber membrane bundle to the gas discharge part provided at the bottom of the bioreactor.

In the method for removing odor and VOC according to the present invention, the step (a) is a low odor or VOC concentration in the inlet gas used as a substrate for the growth of microorganisms, when the growth rate of microorganisms is slow, It is characterized by forming a biofilm by adding a simultaneous metabolite or auxiliary carbon source.

The principle of odor and VOC removal according to the present invention is that the contaminants transmitted through the pores on the filtration membrane are biodegraded by the biofilm formed on the surface of the filtration membrane. The filtration membrane is preferable because the hollow hydrophobic hollow fiber membrane in the fiber has a high membrane filling density (membrane area per unit volume), and the pore size of the hydrophobic hollow fiber membrane is basically commercialized. It can be applied within the range of MF (microfiltration) membrane or UF (ultrafiltration) membrane. The pore sizes of commercially available MF membranes or UF membranes are as follows. In Table 1, the NMWC unit of the UF membrane means a nominal molecular weight cutoff, and is an index indicating the separation performance of the UF membrane as the molecular weight.

UF membrane MF film 1,000 NMWC 0.1 micron 3,000 NMWC 0.2 micron 5,000 NMWC 0.45 micron 10,000 NMWC 0.65 micron 50,000 NMWC 100,000 NMWC 300,000 NMWC 500,000 NMWC

Apparatus and method for odor and VOC removal according to the present invention are effective for the simultaneous metabolism of hardly decomposable chlorine compounds including trichlorethylene (TCE) because they have a harmless VOC population conversion system. Simultaneous metabolism refers to the decomposition of non-growth substrates by microorganisms. That is, the decomposition is performed by the activated microorganism, but the phenomenon is not used as a carbon source or energy source of the microorganism.

In general, hardly decomposable organic substances such as VOCs are classified into the first energy source used as the carbon source or energy source of the microorganism and the late energy source which can be decomposed only when other energy sources coexist, and most chlorine compounds including TCE They are organic substances that can be broken down by microorganisms only when other initial carbon or energy sources are present. This is because an initial carbon source or energy source is decomposed to produce an enzyme called mono- or di-oxygenase, and compounds such as TCE are decomposed by the derivatization of these enzymes.

In addition, according to the present invention, the odor and VOC removal apparatus and removal method, odor and VOC to be used as a substrate in the biodegradation reaction by microorganisms are biodegraded by dilution in the liquid phase, the biodegradable products are also diluted in the liquid phase, thereby suppressing the toxic effect. do.

Using the odor and VOC removal apparatus and removal method according to the present invention, it is possible to easily study the fundamental removal effect of nitrogen, the effect of the gas or VOC addition rate, liquid turbulence and residence time during system operation.

Odor and VOC removal device and removal method according to the present invention has the following advantages compared to the conventional carrier-filled device.

First of all, carriers applied to a carrier filling device are made of compost, ceramic, charcoal, activated charcoal, and the like. These media are not only expensive, but also the volume and weight of the device during filling. This cannot be avoided. At present, in Korea, pollutant gases generated by most industries are discharged to the rooftop. When using a carrier-filled device, securing a space on a narrow site such as a rooftop becomes a big problem. In addition, there is a problem that a large weight is a risk factor for the rooftop installation. The present invention can solve the above installation problem because it uses a light and bulky hollow membrane.

In a device using a carrier, a biofilm is concentrated on the upper layer of the carrier where odors and VOCs are easily accumulated at high concentrations, and clogging phenomenon that frequently causes the excess biofilm to cover the upper layer occurs, thereby increasing the efficiency of removing odors and VOCs. There was a problem falling. Since the present invention uses a hydrophobic hollow fiber membrane, odors and VOCs transmitted through pores distributed over the entire surface of the hydrophobic hollow fiber membrane are distributed at equal concentrations throughout the hydrophobic hollow fiber membrane, thereby solving the problem of clogging. Could.

The present invention solves the problem of clogging as described above, significantly reducing the cost burden due to the cleaning and replacement of aged media. Moreover, compared to the case of using an expensive carrier as a medium, the hydrophobic hollow fiber membrane applied in the present invention is less burdensome to replace in view of the low cost.

In addition, since the apparatus using the carrier has a limit in the amount and concentration of contaminants in the range that the microorganism can treat, there is a limit that cannot be applied under high concentration load and flow load fluctuation conditions. However, the present invention is controlled to transmit the contaminant at an amount and concentration within the range that the microorganism can process through pores distributed throughout the surface of the hydrophobic hollow fiber membrane, so that even at high concentration load and flow rate variation, Stable and excellent processing efficiency of more than%. Therefore, it is not necessary to increase the scale of the device in order to increase the treatment rate, 1/200 of the soil deodorization, 1/5 ~ 1/10 or less of the existing carrier-filled device is applicable.

In addition, the apparatus using a carrier, in order to periodically supply the humidity and nutrients that are essential for the growth of microorganisms to the carrier in which the microorganisms grow, for example, by installing a humidity control device outside the carrier or intermittently spraying water using a spray In this way, it is difficult to maintain the moisture and nutritional conditions at a certain level. However, in the present invention, since the odor and VOC are decomposed by the microorganisms in the microbial culture surrounding the membrane, by adjusting the nutrition and moisture conditions of the culture, it can be easily and easily adjusted to a certain range of conditions.

In addition, the device using the carrier has a long adaptation period for attaching the microorganism to the carrier, and it is difficult for the microorganism to grow evenly throughout the carrier because the biofilm is detached even after it is attached. However, in the present invention, by contacting the microbial culture with the membrane surface, the adaptation period for the microorganism to adhere to the membrane is short, and there is little fear that the biofilm is detached.

Factors to consider in designing odor and VOC removal apparatus according to the present invention are as follows.

Empty bed contact time (EBCT); It refers to the gas residence time in the bioreactor, ie the membrane, and the residence time of the substrate is larger than the gas residence time due to separation between the gas phase, liquid phase and adsorption phase, but proportional to the EBCT. EBCT is a critical design factor when determining reactor size according to the characteristics and decomposition of the inlet gas.

Surface load according to volume gas load; It is also called face velocity because it is often expressed in m / h. The high surface load means that the EBCT is short and the flow rate is high.

Mass load according to mass load per unit reactor volume; The same mass loading may also be different depending on the combination of concentration and flow rate.

Removal capacity according to mass removal rate per unit volume: unit time for a given mass load, VOC mass removal rate per unit volume. As with the mass load, it means the average value for the entire layer, and if the removal rate at an appropriate level is achieved, the removal rate under the same conditions can be compared with the mass removal rate at that time, and this value determines the operating cost. It is a standard.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example

1 is a view schematically illustrating an example of an odor and VOC removing apparatus provided by the present invention, and the process of removing the odor and VOC from the apparatus of FIG. 1 is as follows.

Contaminated air containing odor and VOC was compressed in the compression section 13 and then introduced into the upstream end 4 of the hydrophobic hollow fiber membrane bundle 2 immersed in the bioreactor 3. (5) is an injection pump for introducing contaminated air into the bioreactor 3. A pressure gauge 6 was provided on the air inlet pipe connected to the bioreactor to check the pressure of the inlet air flowing into the bioreactor. The pressure inside the hydrophobic hollow fiber membrane was kept constant so that the microbial culture liquid 1 could not penetrate from the outside of the hydrophobic hollow fiber membrane.

The contaminated air introduced into the bioreactor 3 passed through the hydrophobic hollow fiber membrane bundle 2 and was discharged through the downward end 7 of the hydrophobic hollow fiber membrane bundle. While the contaminated air passes through the hydrophobic hollow fiber membrane bundle (2), the microbial culture solution (1) in which the hydrophobic hollow fiber membrane bundle (2) is deposited, dissolves odors and VOCs inside the contaminated air by gas-liquid diffusion, and Biodegraded by

In order to grow microorganisms in the microbial culture solution 1, a nutrient supply tank 8 for supplying nutrients to the microorganisms was provided outside the bioreactor. On the conduit for supplying the nutrients from the nutrient supply tank 8 to the bioreactor 3, a peristaltic pump 9 was provided to interlock the supplied nutrients.

After the biodegradation reaction by the microorganisms, the gas discharged from the bioreactor is discharged to the hood 10. In order to prevent the growth of the microorganisms in the microbial culture medium, a circulation pump 12 for mixing the microbial culture solution was provided outside the bioreactor.

As a result of experiment using the apparatus of Figure 1, toluene was removed at a removal rate of about 95% TCE and 99% or more when 100 ppm TCE and toluene were mixed and injected. Hydrogen sulfide among odorous substances was removed 99.9% by injection of 300 ppm hydrogen sulfide.

As necessary, such as replacing the aged hydrophobic hollow fiber membrane or replacing the microbial culture medium, the coke of the conduit leading to the drying unit 14 was opened to dry the inside of the microbial reactor.

When using the apparatus and method for removing odor and VOC according to the present invention, the odor and VOC removal efficiency is maintained for a long time, and the odor and VOC are removed at a stable and high efficiency when the concentration load and the flow load change. In addition, it is easy to manage, since the necessary conditions for the growth of microorganisms, in particular, moisture conditions that are difficult to control, can be easily maintained at an appropriate level.

Furthermore, the life span of the hydrophobic hollow fiber membrane applied to the present invention is long and inexpensive, so the burden of the cost of replacing and cleaning the media is small.

Claims (7)

In odor and VOC removal device using microorganisms, A microbial layer surrounding a hydrophobic hollow fiber membrane when a malodorous and VOC-containing gas passes inside the hydrophobic hollow fiber membrane. Reactor; A gas inlet provided at an upper end of the bioreactor to be connected to an upstream end of the bundle of hydrophobic hollow fiber membranes deposited in the microbial culture medium so that gas containing malodor and VOC is introduced into the hydrophobic hollow fiber membrane; And Odor and VOC removal apparatus characterized in that it comprises a gas discharge portion provided at the bottom of the bioreactor to be connected to the lower end of the hydrophobic hollow fiber membrane bundle deposited in the microbial culture medium to discharge the gas passing through the hydrophobic hollow fiber membrane . The method of claim 1, Odor and VOC removal apparatus further comprises a nutrient substance supply tank for supplying nutrition to the growth of microorganisms growing in the microbial culture medium to the outside of the microbial reaction tank. The method of claim 1, Odor and VOC removal apparatus further comprises a compression section for compressing the gas flowing into the hydrophobic hollow fiber membrane to a pressure within a certain range to prevent the liquid outside the hydrophobic hollow fiber membrane to penetrate into the hydrophobic hollow fiber membrane . The method of claim 1, Odor and VOC further comprising a circulating pump to the outside of the microbial reaction tank by mixing the microbial culture medium in the bioreactor to smoothly deliver the nutrients so that the thickness of the microbial layer grown by attaching to the hydrophobic hollow fiber membrane outside the constant Removal device. The method of claim 1, The bioreactor, the odor and VOC removal apparatus, characterized in that the bottom portion is concave so that the dead microbial flocs (floc) dropped off the surface of the hydrophobic hollow fiber membrane can be easily removed. In the odor and VOC removal method using microorganisms, (A) forming a biofilm on the surface of the hydrophobic hollow fiber membrane by depositing a plurality of hydrophobic hollow fiber membrane bundles in a microbial culture inoculated with microorganisms capable of decomposing bad smell and VOC; Odor and VOC-containing gas through the gas inlet provided at the top of the bioreactor including the microbial culture medium and the hydrophobic hollow fiber membrane bundle deposited in the culture medium, in the step (a) upstream of the hydrophobic hollow fiber membrane bundle (B) introducing a; (C) biodegradation of odor and VOC by the biofilm on the surface of the hydrophobic hollow fiber membrane while the gas introduced to the upper end of the hydrophobic hollow fiber membrane bundle in the step (b) passes through the hydrophobic hollow fiber membrane bundle; And Odor and VOC in the step (c) is the odor and VOC is decomposed to the gas discharge unit provided in the lower end of the bioreactor through the hydrophobic hollow fiber membrane hydrophobic hollow fiber membrane downstream end (d) How to remove. The method of claim 6, In the step (a), when the growth rate of microorganisms is low due to a low odor or VOC concentration in the inlet gas used as a substrate for growth of microorganisms, a biofilm is formed by adding a simultaneous metabolite or an auxiliary carbon source to the bioreactor. Odor and VOC removal method.