KR20040068824A - Micro Bio-carrier for fluidizing reactor by using waste slag and fly ash - Google Patents

Abstract

PURPOSE: Provided is a method for preparing a microorganism carrier of a fluidized bed reactor by using waste slag and waste coal fly ash by which provided porous ceramic carrier has good adhesive capacity of microorganisms, enough mechanical strength and large specific surface area. CONSTITUTION: The method comprises steps of (a) mixing a raw material composition consisting of 40 parts by weight of blast-furnace slag and 25 parts by weight of coal, 5 parts by weight of loess, 5 parts by weight of silica stone, 10 parts by weight of bentonite, 10 parts by weight of bentonite and 0.05-0.07 parts by weight of plasticizer; (b) pulverizing the mixture of the step (a) by a ball mill to prepare a ceramic material; (c) molding the ceramic material by using a stainless pelletizer into a spherical shape and drying it; and (d) sintering the molded carrier at a temperature of 1,150-1,200 °C.

Description

Micro bio-carrier for fluidizing reactor by using waste slag and fly ash}

The present invention relates to a method for producing a ceramic porous carrier for more efficient treatment of sewage and wastewater. The present invention relates to slag and coal ash, which are by-products of industrial activities, with a blowing agent, and to controlling a firing time and a foaming amount to provide a wide specific surface area. It relates to a method for producing a ceramic porous carrier having excellent adhesion of microorganisms by forming uniform and fine pores.

Carrier research is carried out in parallel with the development of durable materials that can control porosity, pore size and specific surface area according to materials and applications. Recently, in order to improve the adhesion ability and growth environment of microorganisms, it is mainly using a ceramic material having variously formed micropores. Carriers used for immobilization of microorganisms include polymers, ceramics, activated carbons, and the like, but polymers have a small specific surface area, physicochemical instability, and desorption of microorganisms frequently. In contrast, ceramic-based carriers have the advantages of large specific surface area, physical and chemical stability, and microbial film formation. However, they are difficult to mold into desired shapes and are manufactured by high temperature firing. Has its drawbacks. The high efficiency microorganism immobilized carrier should have a sufficient surface roughness and a large specific surface area of porosity, have physicochemically stable physical properties, and should not release toxic substances from the carrier. In addition, strength and durability must be sufficiently secured, physical property can be easily adjusted and competitive in price. Although wood slag, an amorphous material that generates more than 6 million tons per year in domestic steel mills, has been recycled only as a simple mixed material such as cement or aggregate, but its recycling area needs to be diversified like other developed countries. It is required to develop techniques to increase the added value of these waste by-products.

In general, the microbial porous body is first divided into organic and inorganic according to the material, depending on the carrier shape is roughly divided into spherical, tubular, fibrous, cubic or irregular. In addition, it is divided into high porosity, low pore type, open pore type, waste pore type, macro pore type, micro pore type, etc. according to porosity, pore type and pore size, and depending on reaction tank, it is classified into fluidized bed type and stationary bed type.

The microbial carrier reactor can be classified into a fixed bed and a fluidized bed reactor. A fluidized bed reactor or an air flotation reactor is mainly used for sewage and wastewater treatment, and a fixed bed carrier is used in the odor removal process. Fluidized Bed Biofilm Reactor is divided into aerobic and anaerobic tanks according to the circulation method, internal circulation, external circulation, upflow, downflow, and oxygen supply. Is being used. It can maintain high concentration of microorganisms and can treat large amount of wastewater. The need for a backwashing process to prevent clogging is a distinguishing feature from the stationary phase process. In particular, the fluidized bed reactor may have a height relative to the surface area of the reactor than the packed bed, and a settling tank for solid-liquid separation of the biofilm carrier and the treated water may be installed in the reactor. In addition, the fluidized bed reactor is unstable in removing suspended solids due to sludge bulking, foaming, etc., which is effective for wastewater having a problem in managing the treated water quality.

Accordingly, it is an object of the present invention to prepare a porous ceramic carrier having an easy adhesion of microorganisms, having sufficient mechanical strength and having a large specific surface area. In addition, it was intended to develop a low specific gravity spherical carrier for a fluidized bed reactor effective for aerobic microbial treatment.

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1: Micrograph of microbial carrier-microstructure (porous)

2: Full-scale microbial carrier (spherical)

3: Full-scale microbial carrier (hexahedron)

Referring to the present invention according to the manufacturing process as follows. A raw material composition composed of 40 parts by weight of hand slag and 25 parts by weight of coal, 5 parts by weight of loess, 5 parts by weight of quartzite, 5 parts by weight of feldspar, 10 parts by weight of bentonite, 10 parts by weight of glaze, and 0.05 to 0.07 parts by weight of plasticizer are mixed.

In the present invention, by using a ceramic foam method, which is a unique technique in which the particle filling method and the foam method are mixed, in the manufacture of the ceramic carrier, a product having sufficient economic efficiency and functionality has been developed internationally and competitively.

Micropores formed inside and outside the carrier are generally in contact with each other with a thin film between the bubbles. When the ceramic foam technology is applied, such a film is not closed. In general, the porous ceramic carrier is a sintered granular ceramic, but the ceramic foam can form a porous body having a very high porosity because the pores of the sintered body are ceramics, and the ceramics are pores. The practical use of the ceramic foam is a great advantage that the ceramic foam is obtained in the desired size and shape. In recent years, high interest and evaluation have been gained in this field of ceramic foam in the field of high temperature filter medium or heat exchanger.

In the first step, the raw material is ground into a fine powder using a ball mill to form a ceramic material.

In the second step, the raw material prepared in step 1 is molded into a desired spherical shape using a stainless pelletizer and dried.

In the third step, the molded carrier is fired at 1,150 ° C to 1,200 ° C.

In the fourth step, the finished product is commercialized or reprocessed and polished.

In the present invention, the blending ratio of the raw material is not limited to the above process, and the blending ratio is adjusted according to the characteristics of the manufactured product, the intended use, the quality of the raw material or the firing temperature.

In addition, in the present invention, the microbubbles of the carrier are uniformly distributed and expanded, so that grinding or processing is not necessary, but additional physicochemical treatment may be involved to maximize performance when necessary.

In addition, the porous ceramic carrier of the ceramic material prepared in the present invention has a specific gravity of about 0.9, thereby reducing weight, and having a large specific surface area due to its porosity.

Example 1

35 parts by weight of fine powder of wood slag produced in steel mill, 30 parts by weight of coal ash as a by-product of thermal power plant, 5 parts by weight of loess, 5 parts by weight of quartzite, 5 parts by weight of feldspar, 15 parts by weight of bentonite powder and 0.05 to 0.07 parts by weight of plasticizer. A mixed raw material composition was prepared.

The slag is mainly composed of CaO and SiO ₂ , is a powder with a lot of pores and high permeability, and excellent adhesion of microorganisms. Coal ash whose main components are SiO ₂ , Al ₂ O ₃ and Fe ₂ O ₃ was selected. Fine spherical particles of 100 μm or less, excellent sinterability and large specific surface area. Ocher has the properties of clay, which increases plasticity and contributes to increased dry strength. Quartz is rich in quantity and serves to increase strength. Feldspar has a low softening and melting temperature and high viscosity. In addition, the high viscosity even after the softening point can maintain the shape for a long time.

The particle molding machine was rotated at a speed of about 300 rpm, and 5 parts by weight of glass frit (glaze) and 25 parts by weight of water were mixed in the mixed powder and sprayed onto a stainless steel drum-type particle forming machine. The raw material composition in the granulator was spun until it was granulated into a spherical shape with a uniform size. The composition which became a certain size was fully dried over 2 hours in the temperature range of 120 degreeC.

The dried sintered body was put into an electric furnace and sintered. The sintering conditions were maintained at a heating rate of 5 ° C./min, a sintering temperature of 1,150 ° C., a sintering time of 2 hours or longer, and naturally cooled in a furnace. The sintered body was expanded and foamed to a size of 5 to 10 mm, and in some cases, the carrier was finally prepared by polishing a surface by putting it in a ball mill or the like.

Looking at the measurement results of the physical properties of the prepared porous ceramic carrier, the compressive strength was 78kgf / ㎠, specific gravity was 2.6, the porosity was measured to 11%.

Table 1 shows the main components of slag and coal ash used in the present invention.

Example 2

Recycling slag 40 parts by weight of fine powder of 120 μm or less, 25 parts by weight of coal ash of 63 μm or less, 5 parts by weight of ocher, 10 parts by weight of quartz, 5 parts by weight of feldspar, 5 parts by weight of bentonite powder, and 0.05 to 0.07 parts by weight of plasticizer A mixed raw material composition was prepared.

The mixed powder was poured into a 3.5 L stainless steel molding machine, and 10 parts by weight of glass frit (glaze) and 20 parts by weight of water were mixed and sprayed directly. The particle forming machine was then rotated at a speed of about 300 rpm until the raw material composition in the particle forming machine was granulated to a uniform size. The composition which became a certain size was fully dried over 2 hours in the temperature range of 120 degreeC.

The dried sintered body was put into an electric furnace and sintered. The sintering conditions were maintained at a temperature increase rate of 5 ° C./min, a sintering temperature of 1,180 ° C., a sintering time of 4 hours or more, and gradually cooled from room to room temperature. The final sintered body was 5 to 10 mm in size, and was put into a ball mill or the like to prepare a carrier by polishing the outer surface to be spherical.

As a result of analyzing the physical properties of the prepared ceramic support, the compressive strength was 78kgf / cm 3, the specific gravity was 0.8, and the porosity was measured at 50%.

Tissue photographs of the ceramic porous carrier prepared in Example 2 are shown in FIGS. 1 and 2.

Example 3

Handmade slag 35 parts by weight of fine powder of 120 μm or less and 35 parts by weight of coal ash of 63 μm or less, 5 parts by weight of ocher, 5 parts by weight of quartz, 5 parts by weight of feldspar, 5 parts by weight of bentonite powder, and 0.05 to 0.07 parts by weight of plasticizer A mixed raw material composition was prepared.

After the raw material composition was mixed using a ball mill, 10 parts by weight of calcium carbonate (CaCO ₃ ) and 20 parts by weight of water were added and mixed again. Next, the raw material composition was extruded to granulate to a uniform size, thereby preparing pellets. Compositions of constant size were sufficiently dried in a temperature range of 120 ° C. for at least 2 hours.

The dried sintered body was put into an electric furnace and sintered. The sintering conditions were maintained at a temperature increase rate of 5 ° C./min, a sintering temperature of 1,150 ° C., a sintering time of 2 hours or more, and gradually cooled from room to room temperature. The sintered compact was prepared as a carrier by polishing a surface of the pellet by placing it in a ball mill or the like in a pellet form having a size of 5 to 10 mm.

As a result of analyzing the physical properties of the prepared porous ceramic carrier, the specific gravity was measured as 1.21.

The tissue photograph of the ceramic porous carrier prepared in Example 3 is shown in FIG. 3.

The porous ceramic carrier according to the present invention can pioneer the field of environmentally stable recycling of steelmaking slag and coal ash, which are by-products of industrial activities, and also have a large specific surface area and high mechanical strength, and at the same time, micropores are connected to each other. By having a continuous structure or a continuous net structure of irregular pores, the microorganism can be easily attached and grown on the above porous ceramic carrier can improve the treatment efficiency in wastewater treatment using the microorganism.

Above all, it is believed that the company has pioneered the field of high value-added recycling through the process of appropriately recycling waste. In addition, it is possible to develop a spherical carrier suitable for a highly efficient fluidized bed reactor by developing a carrier structure having a specific gravity lighter than wastewater and wastewater through proper mixing ratio of raw materials and effective heat treatment.

Claims (2)

A method for producing a ceramic carrier for fluidized bed reactors for sewage and wastewater treatment, the method comprising: producing spherical carriers having a specific gravity of 0.9 to 1.1 using a raw material slag and waste coal ash as a main raw material and employing a ceramic foam method. The main raw material is 65% (slag, coal ash), 15% additional raw material, 10% binder, 10% blowing agent, 0.05 ~ 0.07% plasticizer, characterized in that the mixing in the range, sintering from 1150 ℃ to 1200 ℃ by applying glaze as blowing agent Manufacturing method which can maximize foaming effect by selecting temperature.