KR20120093797A - Porous ceramic media for microbes by sawdust and method of manufacturing the same - Google Patents

Abstract

PURPOSE: A porous ceramic carrier for microorganisms based on sawdust and a method for manufacturing the same are provided to cost effectively satisfy the existing property standard of a carrier for microorganisms. CONSTITUTION: A porous ceramic carrier for microorganisms includes a ceramic material and a foaming agent. The content of the foaming agent is 1 to 5 weight% based on 100 weight% of the mixture of the ceramic material and the foaming agent. The ceramic material is based on clay materials with 300um or less of diameters. The foaming agent is based on powdered sawdust or scob with 1mm or less of diameters.

Description

POROUS CERAMIC MEDIA FOR MICROBES BY SAWDUST AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a microbial carrier for recovering contaminated soil and water and a method for producing the same.

The biological purification method of wastewater using the carrier can attach various kinds of microorganisms to the carrier, and it has excellent ability to cope with changes in temperature, pH, insoluble material inflow, etc. Have

In the process of removing contaminants using biological treatment, the amount of microorganisms in the treatment plant is the biggest factor affecting the purification efficiency. In general, microorganisms are grown in suspension or attached to other media in water, and when the carrier is put into an artificial habitat of the microorganisms, the adhesion and proliferation of the microorganisms are increased, thereby increasing the purification efficiency. Generally, polymers and ceramics are mainly used as materials for carriers used for biological treatment. Among the polymer materials, the microstructure is easy to control and has excellent immobilization characteristics of microorganisms, while the pressure loss due to the gel phase is large, and the properties are deteriorated by swelling or magnetization of the carrier itself over long periods of use, and it is disadvantageous compared to inorganic materials in terms of economic efficiency. Thus, research into microorganism attachment carriers using porous ceramic products has been actively conducted.

Republic of Korea Patent No. 0249421, consisting of a filter material consisting of loess, clay, clay and kaolin, adsorbents consisting of diatomaceous earth and zeolite and a blowing agent consisting of calcium carbonate, polyvinyl alcohol (PVA), sawdust or chaff Although a microbial contact medium for wastewater treatment is disclosed, the porosity and pore distribution of the microbial contact medium are not described.

Republic of Korea Patent No. 0434613, a method for producing an immobilized porous ceramic carrier for supporting microorganisms to support microorganisms having a high concentration of capture and resolution of air and water pollutants, a) 70 to 95% by weight of coal ash and ceramic materials 100 parts by weight of ceramic mixed raw material powder containing 5 to 30% by weight, 5 to 35 parts by weight of organic material, 0.1 to 10 parts by weight of organic or inorganic foaming agent, and 60 to 100 parts by weight of inorganic binder aqueous solution of 40 to 80% Mixing to prepare a mixed slurry phase, b) filling the mixed slurry phase into a molding polymer mold and charging it into a continuous drying apparatus maintained at a temperature of 50 to 130 ° C., c) the slurry filled in the mold is used as a foaming agent. Forming a porous molded body by the foaming decomposition reaction and then drying, d) 0.5 minutes ~ 1 in the aqueous solution of 30-100% of another inorganic binder of the colloidal silica component of the dried molded body Impregnating for 0 minutes to absorb the binder to the inside, e) drying and curing the molded body impregnated with the inorganic binder solution at room temperature for 24 hours, and then charging into a constant temperature continuous drying furnace of 200 ° C. or higher, and f again. It discloses a method for producing a microorganism-immobilized porous ceramic carrier for air and water purification, comprising the step of increasing the surface roughness by charging the grinding device to uniformize the surface and shape of the dried and cured molded body, There is a problem in the mechanical durability of the carrier without undergoing a sintering process.

Korean Patent Laid-Open Publication No. 2004-0108403, which prepares 20 to 60% by weight of a media material consisting of loess, clay, clay and kaolin, and organic waste such as food waste, sawdust, husk palm husk, etc., industrial waste 20 to 60% by weight of a foaming agent made of a mixture to obtain a mixture, the mixture is dried in the air and then heated to a carbonized furnace without contacting air at a temperature of 500 ~ 1500 ℃ to prepare a ceramic The present invention discloses a method of manufacturing a ceramic containing activated carbon, but it is not expected to sufficiently fulfill its role as an adsorbent by filling surface micropores due to excessive growth of initial microorganisms.

On the other hand, in order to attach and incubate many microorganisms on a certain carrier, the higher the porosity of the carrier is, the better, and in consideration of the size of the microorganisms in the pore distribution, the higher the porosity ratio than the appropriate size is, the better the application as a carrier for microorganisms.

The present invention is to provide a porous ceramic carrier and a method for producing the same, which can significantly improve the pore distribution for the attachment and habitat of the microorganisms while using economical raw materials while satisfying all the physical property standards of the conventional microbial carrier.

As a means for solving the above technical problem, the present invention is a porous ceramic carrier for microorganisms comprising a ceramic raw material and a blowing agent, based on 100% by weight of the mixture of the ceramic raw material and the blowing agent, the blowing agent 1 ~ 5 wt%, wherein the ceramic raw material is composed of only clay raw material having a particle diameter of 300 μm or less, and only sawdust or soybean rice having a powder form of 1 mm or less is used as the blowing agent, and when the mixture is fired, Provided is a porous ceramic carrier for microorganisms, characterized in that the porosity is 40% or more, and the pores having a diameter of 50 μm or more can occupy 40% or more based on the total pore volume of the carrier.

In addition, in the porous ceramic support for microorganisms including a ceramic raw material and a foaming agent, containing 1 to 5% by weight of the blowing agent based on 100% by weight of the mixture of the ceramic raw material and the blowing agent, the ceramic raw material 300 The slurry is prepared by kneading the mixture, using only sawdust or soybean rice having a powder form of 1 mm or less as the blowing agent, and preparing the compact by compression molding the slurry. In the post-firing, the porous porosity of the microorganism is characterized in that the apparent porosity of the carrier after firing is 40% or more, and the pores having a diameter of 50 µm or more occupy 40% or more based on the total pore volume of the carrier. Provide a carrier.

In addition, in the porous ceramic support for microorganisms including a ceramic raw material and a foaming agent, containing 1 to 5% by weight of the blowing agent based on 100% by weight of the mixture of the ceramic raw material and the blowing agent, the ceramic raw material 300 Using only sawdust in the form of red clay of not more than μm, using only sawdust in the form of powder of 1 mm or less as the blowing agent, the mixture is kneaded to prepare a slurry, the slurry is compression molded to prepare a molded body, and then the molded body is dried and then 1125 ° C. When firing for 2 hours at, the apparent porosity of the carrier after the firing is 40% or more, the microorganism characterized in that the pores having a diameter of 50㎛ or more occupy 40% or more based on the total pore volume of the carrier It provides a porous ceramic carrier for.

According to the present invention, porous ceramics that can improve the pore distribution for the attachment and habitat of microorganisms, while using economical raw materials while satisfying all the physical property standards of existing microbial carriers by controlling the content of ceramic raw materials and blowing agents. The carrier and its manufacturing method can be provided.

1 is a graph showing a particle size distribution of red clay used according to an embodiment of the present invention.
2 is a graph showing the results of XRD analysis on the crystal phase of the carrier (WS) and the commercialization carrier (CP) prepared according to an embodiment of the present invention.
Figure 3a is a photograph showing the results of observing the surface of the carrier prepared according to an embodiment of the present invention with an optical microscope.
Figure 3b is a photograph showing the results of observing the surface of the commercialized carrier with an optical microscope.
Figure 4a is a photograph showing the result of observing 50 times the magnification of the inside of the cut surface of the carrier prepared according to an embodiment of the present invention.
4b is a photograph showing the result of observing the inside of the cut surface of the commercially available carrier by magnification 50 times.
Figure 5a is a photograph showing the result of observing the inside of the cut plane of the carrier prepared according to an embodiment of the present invention by magnifying 1000 times.
5b is a photograph showing the result of observing the inside of the cut surface of the commercially available carrier by magnification 1000 times.
Figure 6a is a graph showing the pore distribution of the carrier prepared according to the embodiment of the present invention.
Figure 6b is a graph showing the pore distribution of the compatible carrier.
Figure 7a is a graph showing the zeta potential according to the pH change of the carrier prepared according to an embodiment of the present invention.
Figure 7b is a graph showing the zeta potential with the pH change of the compatible carrier.

The microorganism ceramic carrier prepared according to the present invention includes a ceramic raw material and a blowing agent, and is a porous ceramic carrier for microorganisms having an apparent porosity of 40% or more and a pore diameter of 50 μm or more and 40% or more. As a material of a carrier used for biological treatment, a ceramic raw material can control pore size suitable for attaching microorganisms, and has excellent chemical resistance, heat resistance, mechanical strength, and affinity with microorganisms. The blowing agent acts as a pore former by generating combustion gases during the preparation of the carrier. The porosity standard currently required for ceramic carriers for soil remediation or water pollution prevention is 40%, and in particular, the size of microorganisms used for water purification is generally about 5 μm. It should be larger than 50㎛) but stable as a habitat for microorganisms. In general, in the case of commercially available carriers, pores having a size of 50 µm or more are known as about 22%. Therefore, the microorganism ceramic carrier prepared according to the present invention provides a porous ceramic carrier for microorganisms that satisfies the porosity standard as a carrier for microorganisms and has a much improved pore distribution than existing commercially available carriers.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the present invention, the ceramic raw material and the foaming agent used to prepare the porous ceramic carrier may use clay raw material and organic waste, respectively, and among the organic waste, sawdust or soybean meal may be used. In an embodiment of the present invention, red clay was used as a raw material for clay, and sawdust was used as an organic waste. That is, in the embodiment of the present invention by mixing sawdust in red clay to prepare a porous ceramics has a physical property suitable for bonding and multiplying microorganisms can be used as a carrier for microbial carriers to restore contaminated soil and water. To this end, the effect of combustion gas of sawdust on the porosity and pore distribution of the prepared carrier was evaluated, and the zeta potential according to pH was measured to analyze the point of zero charge (PZC) of the carrier.

Example

In the present invention, red clay was used as a main raw material of the ceramic carrier, and sawdust was used as an additive for forming pores. The clay raw material was used so that the diameter was 300 μm or less through the first milling using a roller crusher and the second milling using a pin mill. Sawdust powder generated in the wood cattle was used only for the size of 1mm or less as a sieve after drying for 24 hours at 120 ℃. The diameter of the clay raw material and the size of the sawdust powder are limited as described above because a problem occurs in the moldability of the carrier.

The mixing ratio of red clay and sawdust was 95: 5 weight%. If the sawdust is added in excess of 5% by weight, there is a problem that the moldability is sharply lowered, so the amount of sawdust added is preferably 5% by weight or less, and less than 1% by weight, the porosity and pore distribution are not good. Water may be added in an amount of 10 to 20% by weight based on 100% by weight of the raw material mixture for proper stirring and dispersion of the raw material mixture. In the present invention, 15% by weight of water was added and kneaded in a pug mill, followed by compression molding using a circular mold. The compressed molded body was cut into a cube size of 2-3 cm in diameter using a steel wire and dried at 120 ° C. for 48 hours before the surface was dried. The dried molded body was heated at a rate of 10 ° C./min in a shuttle kiln of 4 m 3 and fired at 1125 ° C. for 2 hours. The molded article produced in the present invention was named 'WS', which means that the waste sawdust (waste sawdust) was added, and the commercialization carrier was named 'CP', which stands for 'commercial product'.

Analysis and measurement method in the present invention is as follows.

The chemical composition of the clay raw material was XRF (ZSX-100e, Rigaku Co., Ltd.), and the particle size analysis of the pulverized clay was laser diffraction particle size analyzer (Cilas 1064, CILAS). In addition, the crystal phase of the carrier was analyzed by XRD (RINT-8100H / PC, Rigaku Co., Ltd.), specific surface area of BET (ASAP2010, Micromeritics Co., Ltd.), and pore size and volume fraction by Porosimeter (Pore master, Quantachrome Co., Ltd.). . In addition, the specific gravity and the water absorption of the specimen was measured by applying the test method of 'density and water absorption of coarse aggregate' of KSF2503. Also, Camscope (DCS-105, Sometech vision) and SEM (JSM-6500F, Jeol) were used for the observation of the image and microstructure of the carrier.The surface charge of the carrier was Zeta Potential Analyzer (Photal ELS-8000, Otsuka). Measured using.

The chemical composition of red clay which is a ceramic raw material used according to an embodiment of the present invention is shown in Table 1 below.

division Ignition loss SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO Na ₂ O K ₂ O TiO ₂ P ₂ O ₅ MnO system Red clay
(weight%) 11.0 57.7 19.0 7.1 0.2 1.1 0.1 2.5 0.9 0.2 0.2 100.0

Referring to Table 1, red clay contains 57.7 wt% and 19.0 wt% of SiO ₂ and Al ₂ O _3, which are two basic components of the ceramic triaxial component system, respectively. In addition, 7.1 wt% and 2.5 wt% of Fe ₂ O ₃ and K ₂ O, which are flux components, are contained, resulting in liquid phase sintering. In addition, since the loss of ignition is 11.0% by weight, a certain amount of gas is generated during the firing process. On the other hand, since sawdust is wood powder, it generates a large amount of combustion gas upon firing, contributing to the formation of pores in the sintered body.

1 is a graph showing a particle size distribution of red clay used according to an embodiment of the present invention.

Referring to FIG. 1, after first grinding the red clay with a roller crusher and then second grinding with a pin mill, the average particle diameter of the clay is 28.5 μm, and the particles having a size of 100 μm or more are 7% and particles of 1 μm or less 4% is present.

Hereinafter, the results of the ceramic carrier prepared according to the embodiment of the present invention will be described in detail.

2 is a graph showing the results of XRD analysis on the crystal phase of the carrier (WS) and the commercialization carrier (CP) prepared according to an embodiment of the present invention.

Referring to FIG. 2, both carriers show quartz (SiO ₂ ) as the main crystalline phase, and there are some unknown phases.

The physical properties of the WS and CP carriers were analyzed and the results are shown in Table 2 below.

division In volume ratio Absorption rate (%) Porosity (%) Specific surface area (m < 2 > / g) WS 1.4 31.0 44.5 0.34 CP 1.1 53.1 53.6 0.36

Referring to Table 2, the volume specific gravity and the water absorption of the WS carrier were 1.4 and 31.0%, respectively, and the apparent porosity was 44.5%. In order to attach and incubate many microorganisms on a certain carrier, a higher porosity of the carrier is advantageous. Currently, the porosity standard required for ceramic carriers for soil restoration or water pollution prevention is 40%, so the WS carrier prepared in the present invention satisfies this standard.

On the other hand, commercial carrier (CP), which is known to have excellent microbial adhesion performance, had a specific gravity and absorption ratio of 1.1, 53.1%, and apparent porosity of 53.6%, respectively. CP carriers had 1.7 times higher absorption and 1.2 times higher porosity than WS carriers. As mentioned above, although the WS carrier is slightly heavier and lower in porosity than the CP carrier, the standard porosity required for the general carrier is satisfied.

  The specific surface areas of the WS and CP carriers were not as high as 0.34 m 2 / g and 0.36 m 2 / g, respectively. The low specific surface area of the carrier is due to the formation of many pores tens to hundreds of times larger than nanometer-sized pores. In addition, the liquid phase, which exhibits viscous behavior during sintering, fills open pores and converts them into closed pores, thereby lowering the specific surface area. When microorganisms adhere to the carrier, the specific surface area of the carrier is known as a factor influencing the initial stage of the attachment reaction, but the porosity and pore size have a greater influence on the pollutant treatment efficiency than the specific surface area.

3A and 3B are photographs showing the results of observing the surfaces of the WS and CP carriers with an optical microscope.

3A and 3B, many cracks are observed on the WS carrier exterior surface, which is thought to be due to friction with the steel wire when cutting the molded body. Although it is difficult to judge from this photograph, it was observed that some glass was formed on the surface in actual observation. In the case of CP carriers, there are many spherical pores of constant size. Although it is difficult to judge from the photograph, it was confirmed that a greater amount of glass is present in the CP carrier than the WS carrier.

On the other hand, Figure 4a and Figure 4b is a SEM photograph of 50 times the inside of the cut surface of the WS and CP carrier.

4A and 4B, in the case of the WS carrier, various types of macropores are identified. In particular, the sawdust is burned and the remaining spots appear as needle-like pores, the pores formed by the combustion gas can be seen that a variety of spherical to irregular shape. In the case of the CP carrier, the large spherical pores of 200 ~ 300㎛ or more are observed, it can be seen that the pores are connected to each other.

Meanwhile, FIGS. 5A and 5B are SEM images at 1000 times magnification inside the cut surfaces of the WS and CP carriers.

5A and 5B, in the case of the WS carrier, pores between 10 μm and 100 μm may be checked as well as fine pores of 10 μm or less. In the case of the CP carrier, it is observed that pores of 10 μm or less are closely present.

6A and 6B are graphs showing the pore size distribution of the WS and CP carriers.

6A and 6B, in the case of the WS carrier, pores having a size of 10 to 100 μm occupy 60% of the total pore volume, and micropores of less than 10 μm and macropores of more than 100 μm are 10% and 30%, respectively. Occupies. In the case of the CP carrier, the proportion of pores having a size of 10-100 μm was 70%, which was higher than that of the WS carrier. In addition, the proportion of micropores of less than 10 μm and macropores of more than 100 μm in the total pores of the CP carrier was 20% and 10%, respectively.

  In general, the size of the microorganisms used for water purification is usually about 5㎛, the pore of the carrier is more than 10 times larger than the microorganisms, but stable as a habitat for the microorganisms. In the case of the WS carrier, there are 40% or more of pores having a size of 50 μm or more, which is about 2 times higher than 22% of the CP carrier. Accordingly, the porous ceramic carrier prepared in the present invention has superior pore distribution than commercially available carriers for binding and propagating microorganisms.

7A and 7B are graphs showing zeta potential according to pH change of WS and CP carriers.

7A and 7B, both carriers have a point of zero charge near pH = 2. In other words, the sum of the carrier surface charges becomes '0' at pH = 2. In general, ceramic oxides in contact with water have a hydroxylated surface, and the broken surface reacts with water to have a negative or positive charge through the following equation.

From FIG. 5, the carrier surface has a positive charge in the solution having a lower pH than the zero charge point of the WS carrier, and the carrier surface has a negative charge in the solution having a higher pH. . Therefore, when the microorganism is attached to the carrier, it was possible to know the pH range of the reaction solution that causes the microbial charge on the surface of the carrier. For example, in order to easily attach a microorganism having a surface charge of '+' to the present WS carrier, the pH of the reaction solution may be adjusted to 2 or more. Since the CP carrier has been evaluated as having excellent microbial adhesion properties, the WS carrier having a zero charge point similar to that of the CP carrier will also exhibit excellent microbial adhesion properties.

  As such, the surface charge among the various factors for attaching the microorganism to the carrier is very important. In particular, the surface charge control of the carrier is essential in the process of attaching microorganisms to the carrier in a short time such as nitrification tank.

As a result, the porous ceramic carrier for a microorganism according to an embodiment of the present invention generally satisfies the porosity criteria required for the carrier, and has a similar zero charge point as compared to a commercially available carrier evaluated to have excellent microbial adhesion properties. In the present invention provides a porous ceramic support for microorganisms and a method for producing the same significantly improved than commercially available carriers.

The description of the present invention is for the purpose of illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

Claims (3)

In the porous ceramic carrier for microorganisms comprising a ceramic raw material and a blowing agent,
Based on 100% by weight of the mixture of the ceramic raw material and the blowing agent, containing 1 to 5% by weight of the blowing agent, the ceramic raw material is composed of only a clay raw material having a particle diameter of 300㎛ or less, sawdust in the form of powder of 1mm or less as the blowing agent Alternatively, using only rice paddle, when the mixture is calcined, it is possible that the apparent porosity of the carrier after the firing is 40% or more, and pores having a diameter of 50 µm or more occupy 40% or more based on the total pore volume of the carrier. Porous ceramic carrier for microorganisms, characterized in that. In the porous ceramic carrier for microorganisms comprising a ceramic raw material and a blowing agent,
Based on 100% by weight of the mixture of the ceramic raw material and the blowing agent, containing 1 to 5% by weight of the blowing agent, the ceramic raw material is composed of only a clay raw material having a particle diameter of 300㎛ or less, sawdust in the form of powder of 1mm or less as the blowing agent Or kneading the mixture using only rice paddy to prepare a slurry, compressing the slurry to form a molded body, and drying the molded body after firing, the apparent porosity of the carrier after firing is 40% or more, and the diameter A porous ceramic carrier for microorganisms, characterized in that the pores 50㎛ or more occupy 40% or more based on the total pore volume of the carrier. In the porous ceramic carrier for microorganisms comprising a ceramic raw material and a blowing agent,
On the basis of 100% by weight of the mixture of the ceramic raw material and the blowing agent, containing 1 to 5% by weight of the blowing agent, the ceramic raw material is composed of only red clay having a particle diameter of 300㎛ or less, only the sawdust in powder form of 1mm or less as the blowing agent To prepare a slurry by kneading the mixture, and to prepare a molded article by compression molding the slurry, and after drying the molded article for 2 hours at 1125 ° C., the apparent porosity of the carrier after the firing is 40% or more. And a pore having a diameter of 50 μm or more occupies 40% or more based on the total pore volume of the carrier.

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