KR20010000210A - Biological filter for deodorizing and removing volatile organic components - Google Patents

Abstract

PURPOSE: A biofilter for removal of odor and VOCs from flue gas is provided which shows stable removal efficiency under the wide range of loading and flow-rate conditions. The application of the biofilter is also expected to require less reactor volume and shorter acclimation period than the conventional biofilter. CONSTITUTION: Media are composed of charcoal, polyurethane, and igneous rocks which are produced in Korea and have the diameter of 12-17mm. Seeded microorganisms are Thiobacillus sp. and Bacillus sp.. The process is composed of pretreatment equipment, humidifying equipment, and biofilter as shown in the drawing. Particulate matters are removed from flue gas and the temperature of gas is controlled in order to acquire proper conditions for the next treatment steps by pretreatment equipment. Afterward humidifying equipment supply microorganisms moisture. Actually odor and VOCs are removed by attached microorganisms at biofilter. The currents of flue gas in the biofilter can be downflow (a3) or upflow (b3). It can be achieved to obtain good and stable removal efficiency of 99.9% or higher under high loading-rate and various flow-rate conditions by the process. Therefore, the size of biofilter can be reduced to the half of the conventional biofilter. It can also be achieved to reduce the acclimation period from 1-3 months of conventional biofilter to 15 days.

Description

Biofilter for deodorizing and removing volatile organic components

The present invention relates to a biofilter for removing odors and volatile organic substances (VOCs), and more particularly, stable odors and volatile organic substances in a wide range of operating conditions (low concentration high flow rate, high concentration low flow rate) generated in various industrial sites. It is to provide biofilters to remove odors and volatile organic substances to reduce air pollution generated at the workplace by providing biofilters that can efficiently process VOCs.

In order to remove odors and volatile organic substances, physicochemical methods include direct and catalytic combustion, wet cleaning, and activated carbon adsorption, and biological treatment methods include soil, compost, pit, charcoal, and various organic / inorganic materials as carriers. Biofilter technology has been developed to remove odors and organic substances by microorganisms inhabiting the filling carrier.

The electron physicochemical treatment method has a disadvantage in that it takes a continuous operation cost and generates secondary pollutants.

In the latter biological treatment method, a problem of pressure drop in the filling tower is generated, which requires a large treatment capacity, and a backwashing operation is required during operation.

In addition, the biological treatment method, the physical properties of the filling carrier, the seed inoculation, the contact method with the waste gas, and the like have a great effect on the treatment efficiency.

That is, to summarize the disadvantages of the prior art as described above;

① Excessive installation area: When using organic materials such as soil, compost, pit, charcoal, etc., due to low air permeability, large volume of biofilter is required when low concentration high flow rate flue gas is treated.

② Increased pressure loss and need backwashing: Existing carriers require periodic backwashing due to the increase in pressure loss in the biofilter due to aging and low porosity during filling. Equipment) and excessive waste water generation.

③ Excessive initial adaptation time: In general, when activated sludge is used as a strain of deodorizing microorganisms, the on-site operation is delayed because the adaptation period required for initial operation takes 1-3 months.

④ Unstable treatment efficiency at low concentration and high flow rate: aging of carriers and difficulty in maintaining constant packing microorganisms during long-term operation under low concentration and high flow rate characteristics of odor generated in the field and low diffusion and decomposition rate of odor components As a result, the processing efficiency was unstable.

Therefore, the present invention has a high treatment efficiency for a wide range of pollution loads and flow loads compared to the conventional biological treatment method, and removes odors and volatile organic substances (VOCs) having stable characteristics to the change of the concentration of the incoming waste gas and the change of gas flow rate. In order to provide a biofilter for the present invention, the present invention has been completed.

Figure 1 is a carrier photograph of the present invention (general photograph, electron microscope carrier)

Figure 2 is a microbial picture of the present invention

3A is a schematic diagram illustrating the application of the present invention in the case of a downflow flow.

3B is a schematic diagram illustrating the application of the present invention in the case of upflow flow.

Figure 4 is a mechanism for removing odor and volatile organic substances in the biofilter of the present invention

5 is the removal efficiency and removal of the present invention for each biofilter type according to the space velocity

Chart showing efficiency

■ Explanation of symbols used in main part of drawing ■

1: preprocessor 2: vaporizer

3: Bio filter

Hereinafter, the present invention will be described in detail.

The present invention consists of a carrier and a microorganism filled with a biofilter for removing odors and volatile organic substances (VOCs).

The carrier is a volcanic stone dispersed in Jeju Island, the particle size of 12 ~ 17mm, apparent specific gravity 2.17 g / cm ³ , the water content of 46.52% (w / w) is used. In order to show the characteristics of the product, a general photograph and an electron microscope photograph are attached to FIG. 1.

The microorganisms to effectively remove odors and volatile organic substances are Thiobacillus sp. And Bacillus sp. Micrographs of these microorganisms are attached to FIG. 2.

Figure 3 shows the operation diagram of the biofilter planted with Thiobacillus sp. And Bacillus sp.

In order to apply the biofilter, additional equipment such as a preprocessor (1) and a humidifier (2) is required. The pretreatment 1 removes particulate contaminants present in the exhaust gas and temperature control of the exhaust gas including odor and volatile organic substances (VOCs).

The humidifier (2) is a device that supersaturates the relative humidity of the inlet gas and enters the reactor to supply appropriate moisture to the microorganisms. Continuous spraying at a rate of 2.5% to intensify the gas introduced into the lower part and then discharged to the upper part to flow into the reactor. The humidifier is designed to be 1/3 to 1/5 the size of a biofilter.

The biofilter is a device that absorbs and adsorbs odors and volatile organic substances (VOCs) in the exhaust gas to a microorganism growing on the surface of a carrier and is removed by a biological oxidation reaction.

The media filled in the biofilter should have a large specific surface area, high hardness, and have a constant porosity after filling.

The carrier is filled at 50% of the capacity of the reactor, the porosity of the filling tower is 50%, and the space velocity of the biofilter can be operated even in the range of 60 to 720 / hr. You can keep the loss.

Soil deodorization is impossible due to low air permeability at the space velocity of 50 / hr, and pit drastically drops to 50% removal efficiency at 200 / hr.

Ceramic carriers developed at home and abroad show high removal efficiency at low concentration, but volcanic stone has more than 99.9% removal efficiency regardless of concentration change (30 ~ 300ppm _v ) and space velocity (60 ~ 360 / hr).

The microorganism used in the biofilter of the present invention can maintain a stable treatment efficiency after the initial operation period of about 15 days after planting Thiobacillus sp. And Bacillus sp., Which are highly oxidizing to sulfur and volatile organic substances (VOCs) have.

By these microorganisms, sulfur compounds are sulphates, nitrogen compounds are nitrates, and carbon compounds are decomposed into water with carbon dioxide and are odorless and are removed with carbon dioxide.

Microorganisms completely decompose volatile organic substances (VOCs) such as benzene, toloene and xylene and convert them into energy sources and individual carbon dioxide through oxidation using oxygen.

As such, the final products of the oxidation reaction are H ₂ O and CO _2, so that secondary pollutant emissions, which are problems of other processes, are effectively solved.

The mechanism by which these microorganisms that form and form biofilters on the surface of the filling carrier to remove odorous substances and volatile organic substances (VOCs) is shown in FIG. 4. In addition, these oxidative decomposition reactions of major malodorous substances and volatile organic substances (VOCs) are as follows.

-Odorous substances

-Volatile Organic Component (VOCs)

Pressure loss occurring in the biofilter is operating, if a foreign device is 20~45mmH ₂ O occurs in a space velocity of 200 / hr, but extremely low in the biofilters of the present invention at a space velocity of 240 / hr to 5mmH ₂ O separate backwashing No equipment or additional power costs are required.

The present invention as described above will provide a number of effects as follows.

① Eliminate the economic burden of introducing existing foreign technology and reduce installation and operation costs in workplaces that emit odorous gases and volatile organic substances (VOCs) (1/3 to 1/5 compared to introducing foreign technologies). It is economical, effective, and stable.

② It has a stable treatment efficiency of more than 99.9% at high concentration loads and flow load fluctuations, so it is possible to apply a small capacity of less than 1/200 of soil deodorization and less than 1/2 of existing biofilters.

③ By attaching and growing microorganisms with excellent treatment performance of odorous substances and volatile organic substances (VOCs), initial accelerating period is shortened by fast acclimation period for various odorous substances and volatile organic substances (VOCs) generated in the field.

④ Stable compliance with regulations is possible.

⑤ Examples of the removal of odors and volatile organic substances (VOCs) of the present invention are shown in Tables 1 and 2 below.

(Example 1) Removal of hydrogen sulfide (H ₂ S) among odorous substances Operating conditions Inflow concentration (ppm _v ) Runoff concentration (ppm _v ) Removal efficiency Remarks Inflow Concentration Change Conditions 30-280 0.1 or less 99.9% or more 60 seconds Conditions of change of tower stay time 280 0.1 or less 99.9% or more Removal capacity 132g H ₂ SS / ㎥

Example 2 Removal Characteristics of Toluene in Volatile Organic Compounds Operating conditions Inflow concentration (ppm _v ) Runoff concentration (ppm _v ) Removal efficiency Remarks Inflow Concentration Change Conditions 40-1100 0.1 ppm _v or less 99.9% or more 60 seconds Conditions of change of tower stay time 600 ppm _v 0.1 ppm _v or less 99.9% or more - Removal capacity 740 g / ㎥ · hr -

For reference, the pollutants and discharge facilities that can be treated with the present invention, the emission limit and the emission concentration of the present invention are shown in Table 3 below.

pollutant Discharge facility Emission allowance standard Emission Concentration of the Invention Odor: Sulfur oxide (as SO ₂ ) end. General boiler 540 ppm _v or less 0.1 ppm _v or less I. Power plant 150 ppm _v or less All. Roasting furnace, smelting furnace, molten iron in metal melting, smelting, heat treatment facilities 300 ppm _v or less Volatile Organic Substances: Benzene Compound All outlets 50 ppm _v or less 20 ppm _v or less

Claims (2)

As a carrier filled in the biofilter for the treatment of flue gas containing odor and volatile organic substances (VOCs), a carrier made of porous volcanic stone, charcoal, polyurethane, including Scoria, As planting microorganisms, Thiobacillus sp., Including Thiobacillus Thiooxoans, Thiobacillus Ferroxidans, and Bacillus sp., Including Bacillus Azopoformans, were used. Biofilter for the removal of odor and volatile organic substances (VOCs), characterized in that flowing. The method of claim 1; The carrier (media) filled in the biofilter is filled with 40 ~ 80% of the reactor capacity using a porous volcanic stone, charcoal, polyurethane material, including Sukkorea, Biofilter for removing odors and volatile organic substances (VOCs), characterized in that the porosity of the filling tower is 40 to 80%, the space velocity of the biofilter can be operated in the range of 50 ~ 1000 / hr.