KR100329845B1 - Horizontal bio-filter - Google Patents

Abstract

The present invention relates to a horizontal flow type biofilter capable of removing odorous substances and volatile organic substances such as ammonia, hydrogen sulfide and mercaptan.

In the horizontal flow type biofilter according to the present invention, a plurality of beds are stacked, and an inlet gas containing malodor and organic substances is introduced into the gas inlet 35 installed at the lower left side of the introduction bed 33, and thus, in the introduction bed 33. Firstly filtered by the filtering means embedded in the introduction bed 33 while flowing horizontally and then in the same manner as the introduction bed 33 in the intermediate bed 51, the final filtration after the final filtration in the final bed 61 It is characterized in that the off-gas is discharged to the outside through the discharge port 37 installed on the surface 38.

Description

Horizontal flow type biofilter {HORIZONTAL BIO-FILTER}

The present invention relates to a horizontal flow type biofilter for removing odors and volatile organic substances (VOC), and more particularly, odorous substances such as ammonia, hydrogen sulfide, and mercaptan, and volatile organic substances (Volatile Organic). Compounds (VOCs) relates to a horizontal flow type biofilter, in which a gas flows through each bed horizontally and is filtered by the filtering means contained in the bed.

Environmental foundations such as sewage treatment plants are essential for water conservation, but odors generated during the treatment process cause secondary pollution, which is becoming a major complaint in the area adjacent to the treatment plant. As interest in a pleasant residential environment has increased, the Ministry of Environment Notice No. 1999-45 has established standards for volatile organic compound emission suppression and prevention facilities, which necessitates the necessity to install measures and emission prevention facilities appropriate for domestic conditions.

Odors that normally occur in environmental foundations are hydrogen sulfide, mercaptans, amines, and the like, and have serious effects on volatile organic compounds (VOC) or the environment and human body.

The removal of volatile organic and odorous substances by physical or chemical treatment forms secondary secondary wastes, and economically expensive at low concentrations. For example, traditional volatile organics and odor removal methods, such as thermal oxidation and activated carbon adsorption, are not cost effective for treating various types of pollutants present in low concentrations in large amounts of off-gas, and secondary wastes. Additional processing is required depending on the occurrence. As an alternative, biological treatment methods have been introduced. Biological treatment is more economical than physicochemical treatment techniques such as incineration, activated carbon adsorption, and chemical treatment, and is known to be a very useful technique for purifying large-capacity, low-concentration lubricity air.

The concept of using microorganisms for the biohazardous removal of odorous gases was published by Bach (1923), which introduced the basic concept of hydrogen sulfide control in sewage treatment plants. By 1980, biofiltration was primarily used to reduce odors in wastewater from sewage treatment plants, and in the early 1980s the field of application was extended to the removal of many biologically degradable volatiles.

Formerey (1957) described successful soil filtration in California. The first attempt in Europe was to use soil to treat emissions from compost plants.

The first systematic study of hydrogen sulfide biofiltration in the United States was carried out by Carison and Leiser (1966). Carison and Laser argued that the soil layer would be optimal for bacterial growth, considering temperature, moisture content and pH.

Frechen described the removal of malodorous components carried out by filtration with compost using a water scrubbing at a compost production facility in the city of Duisburg-Huchingen (1972). ). As a result of laboratory-scale experiments using a commercial organic filter, Helmer concludes that the removal of organic odors in the atmosphere can be explained by the mechanism of absorption and the degradation by microorganisms and the reproduction of microorganisms. (1972).

Thistlethwayte and his colleagues studied filtration columns filled with river gravel or glass beads, where nutrient solutions and waste gas flow through counter currents (1973). In the study, the column was planted with activated sludge from the sewage treatment process. Helmer discussed the effects of different types of filter media in another study on the regeneration of filters by microorganisms, thermal and chemical methods (1974). Hartmann replaced the compost every two or three years to maintain the structure of the filter media, based on the results of experiments using biological filtration in the sewage treatment process in Nuremberg, Germany. It was recommended that the water content of the compost be of great importance (1976, 1977).

Guust et al. (1979) suggested that corrosive materials can be used as media for media. In practice, peat and compost are commonly used as media, and the choice of media is determined by its structure, porosity, specific surface area, specific resistance to fluid flow, and moisture retention.

Biological filters have also been reviewed in German sewage treatment. One example is the air purification system of wastewater treatment processes described by Vischer and colleagues (1979). They described how to add a pH-regulating material (usually Dolokal, composed of CaCO ₃ ) to promote the oxidation of organic materials.

Several US researchers have further explored the concept of soil layer biofiltration, demonstrating its usefulness in full-scale applications. In this respect, Bohn has studied theories and the soil layer biofiltration application for more than 15 years (1975; 1986). Winer and Lesson estimated that at that time the total number of biofilter and soil bed images installed in the United States and Canada was less than 50 (1991). As such, biofiltration has been used for odor control.

There are also many reports on the experience of operating biologics in other countries, including Switzerland, Japan and Australia (Devinny et al., 1998).

The deodorization method using microorganisms was patented in the United States in 1957 after the concept of controlling hydrogen sulfide (H ₂ S) gas from sewage treatment plants was introduced in the 1920s. Since then, many soil layer biofilters have been installed and operated in the United States and Canada. Biofilters are used in sewage treatment plants, slaughterhouses and food factories that emit a large amount of low concentrations of waste gas due to their very low facility investment and maintenance costs compared to other air pollution prevention technologies. It is recognized as BACT (Best Available Control Technology).

Biofiltration is a biological treatment system that includes microorganisms in a biofilm formed on the surface of a porous medium such as compost, peat, ceramic, and the like. When the flue gas from the pollutant passes through the biofilter, two basic elimination mechanisms occur: simultaneous absorption / adsorption and biological oxidation. That is, the gaseous pollutants are absorbed or adsorbed in the liquid phase formed on the surface of the filter layer, and are oxidatively decomposed by the microorganisms that grow and adhere to the filter layer through a sufficient residence time.

Although treatment of odors or VOCs by biofiltration has proven to be an efficient, practical and simple biological treatment, such as design and operational parameters or microbiological treatment mechanisms are not well described. In particular, little detailed research has been conducted on the details of biofilter design and operational parameters and the control of odorous gases and volatile organics (VOC). Models for the operation of biofilters have also been developed on the assumption of anomalous flows, but do not include models of biofilters related to non-ideal flows of material to be removed during actual application. Further research is needed to demonstrate the effectiveness of biofilter systems and to develop more efficient biofilters based on an understanding of the basic physical, chemical and biological processes associated with biofilters.

Referring to FIG. 1, in the conventional upflow biofilter, a gas inlet 5 is installed at the bottom of a case 3, an outlet 7 through which the filtered off gas is discharged is installed at an upper surface thereof, and a odor is provided at the bottom of the case. And a mixing chamber (9: mixing chamber) for mixing inlet gas, such as organic material, and air at a predetermined height, and having a predetermined amount of compost and a certain amount of particle size of 5 mm or less on the mixing chamber 9. A first carrier layer (11: first medium floor) in which activated sludge is mixed is disposed, and a second carrier layer in which a predetermined amount of compost having a particle size of 2 mm or less and a predetermined amount of activated sludge are mixed on the first carrier layer (11) 15 is disposed, and an empty space portion 17 is disposed above the second carrier layer 15, and an exhaust gas sampling port is formed at one side wall of the bed to sample the air filled in the empty space portion 17. 19) is installed.

The case 3 is acrylic of a certain thickness on the front side, and the remainder is made of plywood of a certain thickness.

A gas distributor 21 is installed in the mixing chamber 9 to smoothly and evenly supply the inflow gas thereinto, and a reverse injection method is applied to increase the mixing ratio of the inflow gas. In addition, the height of the mixing chamber 9 is about 8 cm.

The ratio of compost and activated sludge mixed in the first carrier layer 11 is about 3000 ml of activated sludge when the compost is 25 kg (wet weight), and the ratio of compost and activated sludge mixed in the second carrier layer 15. Silver compost weighs about 4000 ml with a 35 kg wet weight.

However, the conventional upflow biofilters as described above are not completely discharged due to the removal of odor and volatile organic substances (VOC), the use volume is wide, and its size could not be adjusted.

Accordingly, an object of the present invention is to provide a horizontal flow type biofilter capable of improving the removal capacity and removal efficiency of odor and volatile organic substances (VOC) and miniaturizing the size of the reactor.

The horizontal flow type biofilter according to the present invention for achieving the above object is provided with a filtering means such that the odor and volatile organic material is filtered while the gas containing the odor and volatile organic flows horizontally, the channeling phenomenon of the gas occurs In order to prevent this, a plurality of rectifying plates are provided independently of each other, provided with a predetermined interval between the filtering means, and the beds may be stacked in series of 1 to 100 according to the concentration and load of contaminants introduced therein. It is done.

One example of a horizontal flow type biofilter according to the present invention is a plurality of beds are stacked, the inlet gas such as odor and organic material is introduced into the gas inlet installed in the lower left of the introduction bed flows horizontally in the introduction bed is embedded in the introduction bed After the primary filtration by the filtered means in the middle bed is filtered in the same manner as the introduction bed, the final gas in the final bed is characterized in that the off-gas is discharged to the outside through the outlet installed on the upper surface.

The introduction bed is provided with a mixing chamber for mixing the inlet gas, such as odor and organic matter and air on the gas inlet side, the first rectifying plate is installed after the mixing chamber in the direction of gas flow, the first rectifying plate Next, a first carrier mixed with a predetermined amount of compost and a predetermined amount of activated sludge having a particle size of 5 mm or less is filled, a second rectifying plate is disposed between the first carriers, and the first filtered gas is discharged on the right side of the upper surface. An opening is formed.

The intermediate bed can be stacked from 1 to 98 depending on the concentration and load of the contaminants, and a gas sampling port for sampling the gas discharged from the opening of the introduction bed is provided, and a predetermined amount of compost and a certain amount of particles having a particle size of 2 mm or less. The second carrier is mixed with the activated sludge of the second carrier, the second rectifying plate is installed between the second carrier, characterized in that the opening is formed on the left side of the upper surface.

The final bed is equipped with a gas sampling port for sampling the gas discharged from the opening of the intermediate bed, the second carrier, which is mixed with a certain amount of compost and a certain amount of activated sludge having a particle size of 2 mm or less, is filled to the first rectifying plate, A second rectifying plate is installed between the second carriers, and an empty space portion of a predetermined size is disposed after the first rectifying plate.

The second rectifying plate is characterized in that the hole is distributed in the lower portion and the hole is smaller toward the upper portion, thereby preventing the channeling phenomenon that the gas is driven toward the upper filter carrier.

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

1 is a schematic view showing a conventional upflow biofilter

Figure 2 is a schematic diagram showing a horizontal flow type biofilter according to the present invention

3 is a schematic diagram showing a first rectifying plate according to the present invention;

4 is a schematic view showing a second rectifying plate according to the present invention.

Figure 5 is a schematic diagram of the RTD experiment for comparing the residence time of the horizontal flow type biofilter and upflow type biofilter according to the present invention

Figure 6 is a schematic diagram of the experiment for comparing the odor and volatile organic substances of the horizontal flow type biofilter and upflow type biofilter according to the present invention

7 is a graph illustrating the removal efficiency of the horizontal flow biofilter and the upflow biofilter according to the ammonia loading rate.

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

33: introduction bed 35: inlet

37: outlet 41, 67: first rectifying plate

45, 55, 65: second rectifying plate 49, 57: opening

53, 63: gas sampling port 69: empty space

Referring to FIG. 2, in the horizontal flow type biofilter according to the present invention, a plurality of beds 33, 51, and 61 are stacked so that an inflow gas containing odor and organic substances is installed in the lower left side of the introduction bed 33. Filtered in the same way as the introduction bed 33 in the intermediate bed 51 by first filtering by the filtering means embedded in the introduction bed 33 while flowing into the inlet 35 and flowing horizontally in the introduction bed 33. After the final filtration in the final bed 61, the off-gas is discharged to the outside through the outlet 37 installed on the upper surface 38.

The beds 33, 51, and 61 are each independently manufactured, but are illustrated as stacked in three stages in FIG. 2, but are not limited thereto. Lamination can be installed.

The introduction bed 33 has a mixing chamber 39 for mixing the inlet gas and air containing odors and organic substances on the gas inlet 35 side, the mixing chamber 39 in the direction in which the gas flows Next, a first rectifying plate 41 is installed, followed by a first carrier 43 in which a predetermined amount of compost having a particle size of 5 mm or less and a predetermined amount of activated sludge are mixed. A second rectifying plate 45 is disposed between the first carrier (not shown), and an opening (shown in dotted line) for discharging the primary filtered gas is formed on the right side (when viewed from the drawing) of the upper surface. do.

Although not shown in the drawing, a plurality of second rectifying plates may be spaced apart from each other at a predetermined interval on the first carrier 43 filled between the first and second rectifying plates 41 and 45.

The interval between the arrangement of the second rectifying plate is different depending on the load of the gas.

The intermediate bed 51 may be changed in a variety of stacking from 1 to 98 depending on the concentration and load of contaminants, gas sampling port for sampling the gas discharged from the opening 49 of the introduction bed 33 53 is provided, and a second carrier (not shown), in which a certain amount of compost having a particle size of 2 mm or less and a certain amount of activated sludge is mixed, is filled, and a second rectifying plate 55 is installed between the second carriers. The opening 57 is formed on the left side (when the figure is seen) of the upper surface.

Although not shown in FIG. 2, a plurality of second rectifying plates may be spaced apart from each other at regular intervals on the second carrier 43.

The interval between the arrangement of the second rectifying plate is different depending on the load of the gas. Can be arranged.

The final bed 61 is provided with a gas sampling port 63 for sampling the gas discharged from the opening 57 of the intermediate bed 51, a mixture of a certain amount of compost and a certain amount of activated sludge having a particle size of 2mm or less A second carrier (not shown) is filled up to the first rectifying plate 67, and a second rectifying plate 65 is provided between the second carriers, and the predetermined size is next to the first rectifying plate 67. The empty space 69 of is disposed.

In FIG. 2, only one second rectifying plate 65 is illustrated, but a plurality of second rectifying plates 65 may be installed at a predetermined interval. The spacing of the second rectifying plate 65 may be the same as or different from that of the second rectifying plate installed between the introduction bed and the intermediate bed.

The beds 33, 51 and 61 are acrylics of a certain thickness on the front side, and the remaining portions are made of plywood of a certain thickness.

The mixing chamber 39 is provided with a gas distributor 37 so that the inlet gas is smoothly and evenly supplied therein, and a reverse injection method is applied to increase the mixing ratio of the inlet gas.

The ratio of compost and activated sludge mixed in the first carrier is about 3000 ml of activated sludge when the compost is 25 kg (wet weight), and the ratio of compost and activated sludge mixed in the second carrier is 35 kg (wet weight). When activated sludge is about 4000ml. In addition, the first and second carriers include a post, a peat.

Referring to FIG. 3, holes of about 4 mm are evenly distributed at equal intervals in the first rectifying plates 41 and 67.

Referring to FIG. 4, the second rectifying plates 45, 55, and 65 are formed with holes having a size of 4 mm, and the holes are distributed in the lower portion and the holes are smaller toward the upper portion, so that the gas is concentrated upward. It prevents channeling phenomenon that comes into contact only with the filter carrier.

3 and 4, the holes of the rectifying plate are shown in a circular shape, but are not limited thereto, and may have various shapes such as ellipses and quadrangles.

The openings 49 and 57 are provided with wires or metal meshes.

In the horizontal flow type biofilter according to the present invention as described above, the inlet gas is introduced into the gas inlet 35 and the first rectifying plate 41 and the first carrier by the gas distributor 37 of the mixing chamber 39. It is filtered first through smoothly and evenly. In addition, the gas primarily filtered by the introduction bed 33 is completely filtered while sequentially passing through the carriers of the intermediate bed 51 and the final bed 61. In this case, the channeling phenomenon is prevented by the second rectifying plate 45, and the gas passing through the first and intermediate beds 33 and 51 may be sampled through the gas sampling ports 53 and 63.

The horizontal flow type biofilter according to the present invention constructed and functioning as described above was compared as follows.

Experiment 1

RTD experiments were conducted to determine the flow patterns of both types of biofilters. In the RTD experiment as shown in FIG. 5, since the gas flow rate is an important variable, four different flow rates of 2, 3, 4, and 5 cfm were tested for each biofilter. In the step input experiment, tracer gas (CO2) was used as carbon dioxide and its concentration was maintained at 2000-3000 ppmv.

Table 1 shows the average residence time according to the flow rate of the tracer gas in the conventional upflow biofilter and horizontal flow biofilter.

Average residence time in RTD experiment division Flow rate (cfm) Average residence time (seconds) Upflow Biofilter 2 76 3 60 4 45 5 27 Horizontal Flow Biofilter 2 106 3 84 4 59 5 19

As the air flow rate increased, the residence time decreased, and the residence time of the horizontal flow biofilter was longer than that of the upflow biofilter. At 2 cfm air flow between the two biofilters, the residence time differed the most.

In order to know the hydraulic properties of the two biofilters, the number of continuous complete mixing reactors was calculated from the measured residence time, and the first layer of the horizontal flow biofilter was similar to the two continuous mixing reactors, and the second layer. Was similar to two to three sequential mixers. Thus, the hydraulic properties of the horizontal flow biofilters were more similar to those of a complete mixed reactor. This phenomenon is due to the presence of a commutation plate which causes back mixing in the air flow path. Conventional upflow biofilters have a higher air flow rate, which is closer to the plug flow.

Experiment 2

In the apparatus configured as shown in FIG. 6, in order to investigate the removal efficiency of the malodorous substance, a conventional upflow biofilter and the horizontal flow biofilter of the present invention are used with ammonia gas as the malodorous substance and a concentration of 25ppmv of ammonia introduced therein at 4 cfm. The removal efficiency of ammonia gas was investigated. The results are shown in Table 2 below.

division Inflow concentration (ppmv) Flow rate (ℓ / min) % Removal Upflow Biofilter 25 100 87 Horizontal Flow Biofilter 25 100 100

And, Figure 7 shows the result of comparing the removal efficiency in each bio filter according to the ammonia loading. When the result Upflow For biofilter, when the ammonium load is 1 g NH ^₃ / m ₃ -h and showed the efficiency of removal of _{95~97%, 1 g NH 3 /} m 3 -h or more when the load factor is less than 90 Removal efficiency of less than% is shown. As the load increased, the cutting efficiency decreased. On the other hand, the horizontal flow type biofilter showed 100% removal efficiency when the ammonia loading rate was less than 2.75g NH ₃ / m ³ -h and maintained more than 90% even when the loading rate was 14.3 g NH ₃ / m ³ -h. . This shows that the ammonia removal efficiency and removal capacity of the horizontal flow type biofilter are much larger.

As a result, the removal efficiency of the upflow biofilter was 87%, and the removal efficiency of the horizontal flow biofilter was 100%.

In addition, in order to investigate the removal efficiency of odorous substances, ammonia gas was used and the removal efficiency of the ammonia gas was investigated by using an upflow biofilter and a horizontal flow biofilter at 4ppm at a concentration of 100ppmv of ammonia introduced. The results are shown in Table 3, and the results show that the removal efficiency of the upflow biofilter is 49%, and the removal efficiency of the horizontal flow biofilter is 93%, which is much higher.

division Inflow concentration (ppmv) Flow rate (ℓ / min) % Removal Upflow Biofilter 100 100 49 Horizontal Flow Biofilter 100 100 93

The horizontal flow type biofilter according to the present invention as described above has a longer residence time than the conventional upflow type biofilter, so that the removal efficiency can be increased, and the size can be reduced to 1/2 to 1/4, so that the site is narrow. There is an effect that can be used in environmental foundations, odor and volatile organic substances emission business.

The embodiment of the horizontal flow type biofilter according to the present invention described above is for explaining the idea of the present invention, and the present invention is not limited to the embodiment described above. For example, in the embodiment of the present invention has been described by dividing the bed into three, it will be appreciated that the bed is installed and operated 1-100 if necessary. Those skilled in the art will be able to modify the horizontal flow type biofilter according to the present invention without departing from the scope of the appended claims.

Claims (6)

Filtering means is installed so that malodorous and volatile organic substances are filtered while the gas containing malodor and volatile organic substances flows horizontally, and a plurality of rectifying plates are provided at regular intervals between the filtering means to prevent the occurrence of channeling of the gas. Beds are made independently of each other, the bed is a horizontal flow type biofilter, characterized in that the stacking can be successively stacked 1 to 100 depending on the concentration and load of the pollutants. A plurality of beds are stacked so that an inlet gas containing malodor and organic substances flows into the gas inlet 35 installed at the lower left of the introduction bed 33 and flows horizontally in the introduction bed 33 to the introduction bed 33. After primary filtration by built-in filtering means, it is filtered in the same way as the introduction bed 33 in the intermediate bed 51 and in the final bed 61 after the final filtration in the same way as the introduction bed 33. Horizontal flow type biofilter, characterized in that the off-gas is discharged to the outside through the discharge port (37) installed in. The method of claim 2, The introduction bed 33 has a mixing chamber 39 for mixing inlet gas, such as odors and organic substances, and air at the gas inlet 35 side, and next to the mixing chamber 39 in a gas flow direction. A first rectifying plate 41 is provided, followed by a first carrier 43 in which a predetermined amount of compost having a particle size of 5 mm or less and a predetermined amount of activated sludge are mixed, followed by the first rectifying plate 41. The second rectifying plate 45 is disposed between the carriers, horizontal flow type biofilter, characterized in that the opening 49 for discharging the primary filtered gas is formed on the right side of the upper surface. The method of claim 2, The intermediate bed 51 may be changed in a variety of stacking from 1 to 98 depending on the concentration and load of contaminants, gas sampling port for sampling the gas discharged from the opening 49 of the introduction bed 33 53 is provided, the second carrier is mixed with a certain amount of compost and a certain amount of activated sludge having a particle size of 2mm or less, a second rectifying plate 55 is installed between the second carrier, Horizontal flow type biofilter, characterized in that the opening 57 is formed on the left side. The method of claim 2, The final bed 61 is provided with a gas sampling port 63 for sampling the gas discharged from the opening 57 of the intermediate bed 51, a mixture of a certain amount of compost and a certain amount of activated sludge having a particle size of 2mm or less The second carrier is filled up to the first rectifying plate 67, the second rectifying plate 65 is installed between the second carriers, and the empty space portion 69 is formed by a predetermined size after the first rectifying plate 67. Horizontal flow type biofilter, characterized in that is disposed. The method according to any one of claims 2 to 4, The second rectifying plate has a large number of holes in the lower part of the filter plate, and the number of holes decreases upwards, thereby preventing channeling phenomenon in which gas is concentrated to only one side of the filter carrier, and a plurality of them are spaced apart from each other at regular intervals between the carriers. Horizontal flow type biofilter characterized by the above-mentioned.