KR100653950B1 - Water treatment using porous carriers spported microorganism - Google Patents

Abstract

A water treatment agent obtained by supporting microorganisms on a porous carrier with a porosity range from 20 to 30% manufactured by molding a specific waste material at specific conditions is provided. A water treatment agent is obtained by supporting microorganisms on a porous carrier with a porosity range from 20 to 30% having rice straw. The porous carrier is formed in a shape selected from plate-like, tubular, cylindrical and atypical shapes. The porous carrier is used in the form of a fluidized bed or a fixed bed. The porous carrier comprises rice straw and polymer resin for microorganism supporting. The water treatment agent is used for separating volatile organic compounds contained in water.

Description

Water treatment using porous carriers spported microorganism

1 shows a schematic view of an injection molding machine for molding a porous carrier according to the present invention.

[Explanation of symbols on the main parts of the drawings]

1, 2 and 3: thermoelectric thermometer 4: heater

5: Transfer screw 6: Polyethylene and straw straw storage hopper

Figure 2 shows an electron micrograph of the surface of the porous carrier of Example 3 according to the present invention.

Figure 3 shows an electron micrograph attached to the microorganisms on the surface of the porous carrier of Example 3 according to the present invention.

Figure 4 shows a schematic view of the batch aeration device for water treatment to evaluate the performance of the porous carrier prepared according to the present invention.

[Explanation of symbols on the main parts of the drawings]

1: Rubber Bubble Disperser (Diffuser) 2: Fluidized Bed Media

3: air flow meter

Figure 5 shows by measuring the contact angle to the water in order to examine the affinity of the porous carrier prepared in Example 1 according to the present invention.

Figure 6 shows a schematic diagram of the odor removal device using a biofilter for evaluating the odor removal performance using a porous carrier prepared according to the present invention.

[Explanation of symbols on the main parts of the drawings]

1: filter tower 2: carrier filling part

3: water tank 4: air compressor

Figure 7 shows a SEM photograph of the surface of the porous carrier (Example 2) prepared according to the present invention and the surface of the microorganism is fixed to the carrier.

Figure 8 shows the adhesion of the microorganisms fixed to the porous carrier prepared according to the present invention over time.

Figure 9 shows the odor removal ability using a porous carrier, commercial porous polyurethane carrier and ocher ball carrier according to the present invention.

The present invention relates to a water treatment agent using a porous carrier for supporting microorganisms, and more particularly, to a powder dried rice straw obtained by pulverizing and drying to a specific size and a polyethylene pulverized to a specific size in a certain component ratio, In the carrier obtained by molding under the conditions of the microorganisms, the water treatment agent has the same or more porosity than the conventional carriers, so that the microorganisms are excellent in adhesion, and the by-products of industrial wastes and agricultural products are used as carrier materials. The present invention relates to a water treatment agent using a porous carrier for supporting microorganisms, which is economical and environmentally friendly, and particularly effective in removing odors from sources of odor removal, such as volatile organic compounds.

Due to the rapid economic development, the explosive growth of urban population, and the improvement of living standards, the discharge of various industrial wastes, domestic waste and septic tanks, septic tanks, and livestock wastes, including the increase of water volume, will increase. As such, as the discharge of wastewater increases rapidly, environmental problems such as serious water pollution have emerged, and development of a method for treating wastewater efficiently and economically is required.

In general, there are many problems due to the increase in the proportion of inorganic and organic components in the waste water and wastewater, and efforts to remove inorganic and organic components have been actively conducted.

As a result, the standard activated sludge method and its variations using floating growth of microorganisms are almost universally applied in Korea as a method of treating domestic sewage, agricultural and livestock wastewater, and industrial wastewater.

First, a method of treating wastewater by the activated sludge method is to purify by microorganisms stuck to a contact medium serving as a carrier, and various bio phases are fixed to the contact medium, thereby increasing the efficiency of water treatment. This activated sludge method has the advantage of fast biochemical reaction rate, small amount of excess sludge because it promotes self-oxidation of sludge, and excellent treatment efficiency for low concentration wastewater treatment.

The most important parameter of the catalytic oxidation method using the contact media is the performance of the contact media. In general, various materials such as sand, gravel, glass, ceramic, charcoal, plastics and fibers are used as the contact media.

Among these contact media, in the case of sand, gravel, glass, etc., the surface is smooth and difficult to attach microorganisms, and ceramics are made of porous materials, and are excellent in performance, but are difficult to manufacture and economically disadvantageous. In addition, the use of polyethylene, polypropylene, polyvinyl chloride and nylon fibers has been attempted as a medium for plastic materials, but despite the advantages of easy processing, the rate of microorganisms is low and the specific surface area is generally low. Development is required.

Accordingly, the present inventors have tried to solve problems such as the material, economical efficiency and efficiency of the contact medium to support the biological material in the method for treating wastewater by the activated sludge method as described above. As a result, when the powder-dried rice straw obtained by pulverizing and drying to a specific size and the polyethylene pulverized to a specific size are mixed, it is applied to a water treatment in which microorganisms are supported on a carrier obtained by molding at a specific temperature range. Compared to the conventional method, the porosity of the carrier is improved by using rice straw with high hydrophilicity, and the adhesion of microorganisms is improved, and the economic efficiency is improved by using recycled materials. Especially, it contains volatile organic compounds, phosphorus and nitrogen contained in water. The present invention has been found to be excellent in the odor removal ability of odor removing substances such as compounds.

Accordingly, an object of the present invention is to provide a water treatment agent in which microorganisms are supported on a porous carrier having a porosity in the range of 20 to 30% by molding a specific waste material under specific conditions.

The present invention is characterized by a water treatment agent containing microorganisms on a porous carrier containing rice straw and having a porosity of 20 to 30%.

Hereinafter, the present invention will be described in detail.

The present invention relates to a water treatment agent in which microorganisms are supported on a porous carrier for supporting microorganisms, by mixing powder dried rice straw under a specific condition and a polymer resin for supporting microorganisms pulverized to a specific size in a certain component ratio and molding at a specific temperature. The present invention relates to an effective water treatment agent in the field of water treatment, such as wastewater and wastewater, by forming a porosity in the range of 20 to 30%, thereby improving the adhesion of microorganisms, and consequently improving the decomposition rate of organic substances.

In addition, it is not particularly limited to a polymer resin that is commonly used as a material of the carrier, specifically, polyethylene, polypropylene, polyterephthalate, etc. may be used, and waste industrial polyethylene, waste polypropylene, waste poly terefe, which are industrial wastes thereof. The use of thallate is possible. By using rice straw which is a by-product of crops mixed with the microorganism-supporting polymer resin, the manufacturing cost is low, and it is excellent in degradability compared with the prior art, thereby obtaining an environmentally friendly effect.

Conventionally, sand, gravel, glass, ceramics, charcoal, plastics, and fibers have been used as materials for carriers, but these have limitations in use due to disadvantages in microbial adhesion and material economy and efficiency. The present invention is characterized in the technical configuration in the method for producing a porous carrier molded in a specific manner by industrial wastes and by-products of crops in order to improve the above disadvantages. Compositions using industrial wastes and by-products of crops have already been known in many publications.

The present invention is not characterized by the use of such a component, but in order to improve the adhesion of microorganisms and improve the porosity of the carrier, in order to impart a hydrophilic group, the hydrophilic property of rice straw is used in the polymer resin component used as a conventional microbial carrier. It is given. That is, although the hydrophilic group can be introduced into the polymer resin by a chemical method, the present invention has a feature of technical construction to impart hydrophilicity by a biological and environmentally friendly method.

In addition, there is an important feature in terms of waste recycling by using a high-molecular polymer resin and rice straw which is a byproduct of crops.

Among the polymer resins, resin components such as polyethylene generally have small surface free energy and strong hydrophobicity, and have negative charge surface charge in the neutral region. Therefore, in the case of forming a carrier prepared from the raw material, the carrier has high hydrophilicity in order to facilitate the adsorption and growth of the microorganisms on the carrier since the adsorption of the microorganisms with a negative surface charge and a strong hydrophilicity is not easy. do.

Looking at the method for producing a water treatment agent using a porous carrier for supporting a microorganism according to the present invention in more detail as follows.

First, the rice straw powder is oven dried. The rice straw is not particularly limited to a general grinding method used in the art, but in the present invention, after cutting to a certain size, the rice straw is pulverized using a willy mill, the rice straw is properly formed but preferably 40 to 80 It is better to form a range of mesh. Since the size of the rice straw is an important factor acting on the specific surface area and dispersibility, it is preferable to use it in the above range. If the particle size is fine and the specific surface area is large, it absorbs moisture in the air, which makes it difficult to carry out molding operations. On the contrary, if the particle size is large, the degree of miscibility is low, resulting in uneven dispersibility. Size is also important.

Thereafter, the rice straw powder is dried for 4 hours or less, preferably 3 to 4 hours at a temperature of 100 to 120 ℃ bar, if the drying temperature is less than 100 ℃ free water contained in tissue cells of rice straw (Free water) is not completely removed, a problem occurs during molding, and when it exceeds 120 ℃, the problem of physical properties change due to deformation of the cell structure. In addition, when the drying time is out of the condition does not occur, it is preferable to maintain the above range.

Next, 5 to 20% by weight of the dried rice straw powder prepared above and 80 to 95% by weight of the polymer resin powder are mixed. In this case, the polyethylene is used in a suitable size for the process efficiency, preferably 5 to 10 mm crushed. If the size of the powder is too fine, it is preferable to maintain the above range because a problem of causing a load on the motor of the molding machine occurs when the raw material transfer is not smooth and the particles are large.

 Preferably, the polymer resin is used by mixing 80 to 95% by weight with 5 to 20% by weight of powdered rice straw. If the amount of the powdered rice straw is less than 5% by weight, the formation of pores of the formed carrier is small, and microorganisms are fixed. If the efficiency is reduced, if the amount exceeds 20% by weight, rice straw powder absorbs moisture in the air, so that molding is difficult, so it is preferable to maintain the above range.

 In addition to the above-mentioned polymer resin and rice straw, an additive used for the purpose of improving the adsorption of microorganisms may be additionally used in the art without departing from the object of the present invention, and the additives include clay, activated carbon, and the like. have.

 Next, a carrier is prepared by molding the mixture prepared above. The molding is used in the art, but is not particularly limited, and in particular, a carrier having a plate shape, a tubular shape, a cylindrical shape, and an irregular shape may be prepared according to the use used by extrusion molding, injection molding, and the like.

At this time, it is preferable that the molding temperature is maintained at a range of 150 to 250 ° C. If the molding temperature is less than 150 ° C., the raw material is not smoothly transferred from the molding machine. It is advisable to maintain this range because one problem arises.

Next, Figure 1 is an example, a method for producing a carrier using an injection molding machine, mixed with powdered dried rice straw in the pulverized waste polyethylene into the hopper (6) and stirred for 5 to 30 minutes at a rotational speed of 50 to 100 rpm The mixture obtained by mixing is transferred forward by melting with a transfer screw 5 at 10 to 30 rpm under the condition that the thermoelectric thermometer 1-3 is maintained at a temperature of 170 to 200 ° C by the heater 4. The molded product passed by the transfer is cut into a predetermined length of 10 mm with a cutter to produce a pellet.

Fibers of rice straw by the method according to the present invention as described above is bonded to the polyethylene like a network structure, and some carbonized shrinkage to form a rough surface to increase the specific surface area and to form a lot of voids in the outer surface and the inside.

 Next, a microorganism is supported on the carrier prepared above to prepare a water treatment agent. The present invention has a feature in the technical configuration of a porous carrier in which rice straw is introduced in a biological and environmentally friendly way to impart hydrophilicity to a polymer resin used for supporting microorganisms. The microorganism loading is more effective.

That is, the microorganism used in the present invention is not particularly limited to those that are commonly used in water treatment, specifically, the geo-tree glutamicum (Geotrichum system), Pseudomonas (Pseudomonas based), Bacillus (Bacillus system) bakteo (Arthrobacter System as Aspergillus ), Enterobacter ( Enterobacter type ), Citrobacter ( Citrobacter type ) and Corynebacter ( Coynebacter type ) and the like can be used. And widely used because the production of the addition have had an excellent waste resolution Bacillus genus in a dual protection spore form, geo-tree glutamicum (Geotrichum system), Pseudomonas (Pseudomonas system) and the like of the volatile organic compounds such as aromatic compounds such as toluene and It is widely used because it shows an excellent effect on the odor removal ability of odor-causing substances containing nitrogen.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention thereto.

Example 1

The straw was cut into a 3 cm size with a cutter, then pulverized with a Willie mill, passed through a 40-80 mesh sieve, and then powdered, and dried at 105 ° C. for 1 hour.

95% by weight of waste polyethylene cut to a size of about 5 mm was mixed by molding 5% by weight of the rice straw powder.

At this time, as the molding is shown in the schematic diagram of the injection molding machine of FIG. 1, the mixture is stirred and mixed for 10 minutes at a rotational speed of 70 rpm in the hopper 6, and the mixture is heated to the thermoelectric thermometer 1-3. It was maintained at a temperature in the range of 180 ° C and transferred forward while melting with a transfer screw 5 at 15 rpm. The molded product passed through the transfer was cut into a predetermined length of 10 mm with a cutter to prepare a porous carrier on a cylindrical pellet having a diameter of 5 mm.

Example 2

In the same manner as in Example 1, using a waste polyethylene 90% by weight and rice straw powder 10% by weight to prepare a porous carrier.

Example 3

In the same manner as in Example 1, a porous carrier was prepared using 85% by weight of waste polyethylene and 15% by weight of straw straw powder.

An electron micrograph of the surface of the porous carrier prepared above and an electron micrograph of microorganisms attached to the surface of the carrier are shown in FIGS. 2 and 3, respectively.

Example 4

In the same manner as in Example 1, a porous carrier was prepared using 80% by weight of waste polyethylene and 20% by weight of straw straw powder.

Comparative Example 1

Carried out in the same manner as in Example 1, using 100% by weight of waste polyethylene.

Comparative Example 2

The carrier was prepared in the same manner as in Example 1, using 90 wt% of waste polyethylene and 10 wt% of clay.

Comparative Example 3

A carrier was prepared in the same manner as in Example 1, using 90 wt% of waste polyethylene and 10 wt% of activated carbon.

The porosity of the porous carriers prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was measured, and the results are summarized in Table 1 below.

division Porosity (%) Example 1 21.93 Example 2 23.20 Example 3 27.30 Example 4 28.56 Comparative Example 1 7.15 Comparative Example 2 18.00 Comparative Example 3 22.67

As shown in Table 1, it was confirmed that the porosity of the carriers of Examples 1 to 4 using the mixed straw in accordance with the present invention is equal or higher.

Experimental Example 1

In order to determine the performance of the porous carrier prepared in Examples 1 to 4, the following experiment was performed.

Next, as shown in Figure 4, the batch acrylic aeration device consisting of four zones, each 10L of food wastewater and 10% by volume of each of the porous carriers prepared in Examples 1 to 4, and then the Bacillus powdery seed Each system (BioENT, Biomax) was added 1,000 mg / L each. Thereafter, while maintaining 30 L / min was supplied to be uniformly distributed through the diffuser. At this time, the food wastewater chemical oxygen demand (COD) was 17,700 mg / L, biological oxygen demand (BOD) was maintained at 18,120 mg / L.

The process is a process in which the microorganisms adhere to the porous carrier, and the change in the chemical oxygen demand and the biological oxygen demand is observed for 7 days while the performance of the porous carrier is shown in Table 2 below.

division COD / BOD (mg / L) 0 days 2 days 4 days 6 days 7 days Example 1 17,700 / 18,120 9,800 / 7,500 / 2,200 / 2,400 / 5,196 Example 2 17,700 / 18,120 7,500 / 8,600 / 2,400 / 1,200 / 4,776 Example 3 17,700 / 18,120 7,000 / 5,600 / 3,000 / 1,140 / 3,318 Example 4 17,700 / 18,120 7,100 / 5,100 / 1,300 / 750 / 2,052

Experimental Example 2

After performing Experimental Example 1, in order to evaluate the performance of the porous carrier to which the microorganisms were fixed, the new food wastewater was replaced by 10 L, and the chemical oxygen demand and the biological content for 7 days while dispersing 30 L / min of air were filled. The change in oxygen demand was observed and the results are shown in Table 3. At this time, the chemical oxygen demand (COD) of the food wastewater is 5,250 mg / L, biological oxygen demand (BOD) is 7,230 mg / L.

division COD / BOD (mg / L) 0 days 1 day 2 days 3 days 4 days 5 days 6 days 7 days Example 1 5,250 / 7,230 3,900 / 3,275 / 2,600 / 1,100 / 1,020 / 720 / 670 / 2,862 Example 2 5,250 / 7,230 3,100 / 1,375 / 1,100 / 860 / 790 / 650 / 600 / 2,103 Example 3 5,250 / 7,230 3,100 / 1,250 / 1,900 / 1,300 / 230 / 270 / 230/317 Example 4 5,250 / 7,230 2,300 / 2,375 / 1,620 / 1,400 / 470 / 210 / 120/335

Experimental Example 3

Experimental Example 1 was carried out in the same manner, but the performance of the carrier of Example 2 and Comparative Examples 1 to 3 were measured and compared, and the results are shown in Table 4 below. In this case, the chemical oxygen demand (COD) of food wastewater is 47,000 mg / L, the biological oxygen demand (BOD) is 69,200 mg / L, and the change in chemical oxygen demand and biological oxygen demand for 12 days was observed and the results are shown in the table. 4 is shown.

division COD / BOD (mg / L) 0 days 3 days 6 days 9 days 12 days Comparative Example 1 47,000 / 69,200 41,400 / 39,000 / 31,800 / 29,400 / 19,900 Comparative Example 2 47,000 / 69,200 39,200 / 37,800 / 33,200 / 26,300 / 20,100 Comparative Example 3 47,000 / 69,200 36,300 / 26,700 / 24,800 / 23,700 / 18,200 Example 2 47,000 / 69,200 38,900 / 34,700 / 27,400 / 16,100 / 16,700

Tables 2 and 3 show the performance of the carriers prepared in Examples 1 to 4 according to the present invention. As the amount of rice straw used as the reaction material increases, the COD and BOD levels decreased.

In addition, Table 4 shows a carrier (Example 2) prepared by using straw straw in the waste polyethylene prepared according to the present invention, and a carrier prepared by mixing clay and activated carbon in waste polyethylene alone, waste polyethylene as a comparative example thereof ( Comparing the performance of Comparative Examples 1 to 3), the carrier of Example 2 according to the present invention was confirmed that the water treatment performance is improved compared to the carriers of Comparative Examples 1 to 3, the value of COD and BOD over time As the reduction rate was large, it was confirmed that the carrier of Example 2 was excellent in the storage stability of the microorganism.

Experimental Example 4

In order to examine the affinity according to the material of the porous carrier prepared in Example 1 was measured in the contact angle to the water shown in Figure 5 below.

Next, as shown in FIG. 5, polyethylene alone (PE) was measured as high as 75 °, but when 5% by weight of straw (RS) was added as in Example 1, the contact angle was significantly lowered to 46 °. However, when rice starch and starch with similar chemical composition were mixed, it was measured as high as 65 °. That is, it was confirmed that the hydroxyl group of glucose, which is the main component of rice straw, strongly bound with water to swell the fiber, and the hydrophilicity was different from starch due to the difference in the binding structure of the glucose unit.

Therefore, in summary, when the pepolyethylene and rice straw were molded under specific conditions according to the present invention, it was found that porosity was formed so that microorganisms were well adhered and propagated, and efficient water treatment was possible.

Experimental Example 5

After fixing the microorganisms to the carrier of Example 2 (90% by weight polyethylene + 10% by weight straw straw), commercial porous polyurethane carrier (Poly Urethane) and loess ball carrier (Loess Ball), using this, a volatile organic compound Odor elimination experiment was performed. At this time, the microorganism is a geo-tree glutamicum (Geotrichum) to step sp.TKD Pseudomonas, Pseudomonas sp. SKA, Pseudomonas sp. AKC, Pseudomonas sp. VKA and Pseudomonas (Pseudomonas) to step Geotrichum sp. MKA, Geotrichum sp. MKB, Geotrichum sp. MKC, Geotrichum sp. MKD was fixed on the carrier using a 1: 1 ratio by weight.

Deodorization is carried out using the bio filter device shown in FIG. 6, wherein each carrier is filled with 20% by volume (1 L) of the filter tower, and as a nutrient source in a water tank containing 15 L of tap water. 1.5 g / L KH ₂ PO ₄ , 6.0 g / L Na ₂ HPO ₄ , 3.0 g / L (NH ₄ ) ₂ SO ₄ , 0.05 g / L MgSO ₄ and 0.01 g / L CaCl ₂ . This nutrient was sprayed at a rate of 7 L / min at a flow rate of 7 L / min every 10 hours for 10 days to fix microorganisms on the surface of the carrier.

In order to confirm the adherence of the microorganism was inoculated in a liquid medium and a sample was taken. Next, FIG. 7 shows SEM photographs of the carrier surface before the microorganisms are fixed and the surface of the carrier after the microorganisms are fixed.

Thereafter, samples taken at different time zones were plated on a solid medium, and the number of microorganisms and activities were observed as shown in FIG. 8 and Table 5 below.

Sampling time after inoculation (hours) Microbial Count 2 1200 6 16000 15 Difficult to quantify (large volume)

As shown in Table 5 and FIG. 8, when incubated for 2 hours, it was confirmed that the microorganisms were fixed on the surface of the carrier, and it was found that the number of microorganisms was continuously increased as the incubation time elapsed. From this, it was confirmed that the microorganisms attached to the carrier maintain high activity.

After confirming the fixation of the strain in the above, using the toluene as a volatile organic compound to perform the experiment to confirm the odor removal ability according to each carrier (carrier of Example 2, commercial porous polyurethane carrier, ocher ball carrier) Next, it is shown in FIG.

At this time, in order to supply liquid toluene as a gas, a small bottle (bottle) aeration method, toluene was filled in the bottle and air was supplied to cause odor. The odor was injected at 2 L / min, and a small amount of toluene gas was mixed with air supplied from an air compressor to control the concentration of the gas.

As shown in FIG. 9, the commercial porous polyurethane carrier (PU) and ocher ball carrier (LB) exhibited an odor removal efficiency of 50 to 60% on the basis of 6 hours, and polyethylene and rice straw powder according to the present invention. In the case of the carrier of Example 2 used in combination, high odor removal ability of 80% or more was confirmed.

As described above, according to the present invention, a carrier obtained by molding rice straw, which is a by-product of crops, under a specific condition, in the polymer resin component has improved porosity compared to a conventional carrier, thereby increasing the adhesion and propagation effect of microorganisms It can maximize the decomposition effect, and it is economical because it uses wastes and by-products. Especially, it has great ability to remove odors from odor-causing substances such as volatile organic compounds. It is expected.

Claims (5)

A water treatment agent comprising rice straw and having microorganisms supported on a porous carrier having a porosity of 20 to 30%. The water treatment agent of claim 1, wherein the porous carrier has a shape selected from a plate, a tubular shape, a cylindrical shape, and an irregular shape. The water treatment agent according to claim 1, wherein the porous carrier is used in the form of a fluidized or fixed bed. The water treatment agent according to claim 1, wherein the porous carrier comprises rice straw and a polymer resin for supporting microorganisms. The water treatment agent according to claim 1, wherein the water treatment agent is used for separating volatile organic compounds in water.

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