JPS63175695A - Porous carrier for microorganism - Google Patents

Abstract

PURPOSE:To enhance affinity for organisms by adding clay and lime to 'SHIRASU' (volcanic glass) and fly ash being main components and adding a pore forming agent to the mixture and calcining it. CONSTITUTION:Clay not less than 10wt.%, 5-20wt.% lime and a pore forming agent such as rice bran, walnut powder and coke are added to 'SHIRASU' (volcanic glass) or fly ash and the mixture is molded. This molded form is calcined at temp. of 700-900 deg.C for 1-3hr. A porous carrier for microorganisms is formed by this calcined form and the activity of microorganisms can be held at a high level by immersing it in sewage.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is applicable to biological treatment of sewage in which microorganisms are attached to a filler in a 1y, 8-shape, and the sewage is treated by bringing the sewage into contact with the biofilm of the microorganisms. The present invention relates to microbial carriers to be used, particularly microbial carriers suitable for adhering activated sludge and methane bacteria, and particularly to microbial carriers with low tolerance.

(Prior art) Conventionally, wastewater biofilm treatment methods include fixed bed type and fluidized bed type. Of these, in the fluidized bed type treatment method, both wastewater and filler must be fluidized, resulting in a large Because power is required, microorganism retention jU (20,000 to 40,000 mg/
Despite the high Q, the fixed bed treatment method (8000 ~
40,000mg/Q) has also been administered. Microbial carriers that hold microorganisms, such as shells, coral, and blast furnace slag, have been used as carriers in this fixed bed treatment method. Also, JP-A-59-449:1 and JP-A-60
-1438!16, there is an invention in which a catalytic oxidation purification medium (carrier) is molded with inorganic aggregate such as fly ash and cement in the presence of water, or this molded product is fired. .

(Problems to be solved by the invention) In general, in the field of sewage treatment, members used, especially carriers, have a constant shape, have good sewage treatment efficiency, have good affinity with living organisms, and are inexpensive. Things like that are required.

However, when natural materials such as shells and corals are used as microbial carriers, their shape and size are not constant, resulting in uneven flow of wastewater when filled into a treatment tank. In addition, the latter molded fly ash disclosed in JP-A No. 59-4493 has low strength in water;
No. 1/13806 requires a long curing time as seen in, for example, Japanese Patent Publication No. 61-52116, since the cement hardened product is fired, and the production efficiency of the carrier cannot be said to be good, and moreover, it requires special technology. It was necessary to do so, and the cost had to be high.

(Unexamined Japanese Patent Publication No. 143896/1986 tested with 28 daily temperature-treated organisms) (Means for solving the problem) The present invention was developed in the southern Kyushu area while making prototypes to solve the above-mentioned problems of the prior art. The main materials are Shirasu, which is naturally available in inexhaustible quantities, or fly ash, which is a waste product from thermal power plants, etc., and a certain amount of clay and lime is added to this, and a pore-forming agent is added to this and molded. 900'C
They discovered that it is sufficient to fire the paper at a low temperature of 170°C for 1 to 3 hours, and have accomplished the present invention.

In the present invention, clay is set to 10% by weight or more in the carrier composition because if it is less than this, the function as a melting agent during sintering of Shirasu, the main raw material, will be insufficient, and the maximum temperature during firing will be 1.
This is because the temperature exceeds 1,000°C and the firing time is also long. Further, even if 20% by weight or more is added, the firing temperature does not decrease and the firing cost 1- does not decrease.

Incidentally, the whitebait of the present invention can be used as it is from volcanic ejecta or its deposits, and the fly ash used is fly ash that has been collected using an electric or Cottrell type dust collector.As for the clay, Honbushi clay or Frogme clay can be used. Rat lime is used as the lime, and as a pore forming agent,
Sawdust, rice bran, walnut flour, coke, etc. are used.

Further, the shape of the carrier may be a ring shape, a saddle shape, or a ball shape, and the thickness of the molded body is preferably about 1 to 5 mm in consideration of the growth of living organisms.

(Example) Examples of the present invention will be described below.

Example 1 Fly ash 800g Kibushi clay 200g and pore forming agent (sawdust) 100g rat lime
200g is kneaded with 0.3Q of water in a kneader, and the mixed raw materials are formed into a cylinder shape with an extruder, dried, and then fired in a firing furnace at a maximum temperature of 900°C and a J4 temperature/lowering temperature for 60 minutes.

The resulting carrier had an average pore diameter of 12 μm, a porosity of 35%, and a surface roughness of 92 μm as a ten-point average roughness.

Example 2 Fly ash 800g Honbushi clay 200g Pore forming agent (sawdust) 200g Mouse lime
200 g was kneaded in the same manner as in Example 1, formed into a saddle shape using an extruder and a roller machine, and after drying, was fired in a firing furnace at a maximum temperature of 900° C. for 60 minutes with heating and cooling.

The resulting carrier had an average pore diameter of 20 μm and a porosity of 52%.

Example 3 Shirasu 800g Honbushi clay 200g Pore forming agent (sawdust) 100g Mouse lime
200 g was mixed, extruded, dried and fired in the same manner as in Example 1. The average pore size of the resulting carrier is 5μI
n, the porosity was 52%.

(Effects) According to the present invention as described above, the following effects can be achieved. (1) Shirasu and fly ash, which are the main raw materials of the carrier of the present invention, are inexhaustible natural products or can be used as waste. It is desired to utilize it, and since it is used as the main raw material, carriers can be manufactured at low cost. In addition, since this shirasu or fly ash is sintered together with clay and lime, sintering can be performed at low temperatures and in a short time. Combined with the low cost of the raw materials mentioned above, the carrier can be produced at an extremely low cost.

(2) Furthermore, the carrier of the present invention contains clay and lime as described above, and is fired at a low temperature and in a short time.
The above-mentioned inorganic substance is sintered at the same time as the pore-forming agent is burned out, and the pores caused by the pore-forming agent are not densely filled with shirasu, fly ash, clay, and lime, and the pore-forming agent is sintered depending on the particle size and blending amount of the pore-forming agent. 1. Since the pores are formed faithfully, the diameter and distribution of the pores can be easily controlled, and this method is suitable as a method for producing carriers for microorganisms where washing out the microorganisms is a problem.

(3) Furthermore, since the carrier of the present invention contains limestone as a raw material, when the carrier is immersed in waste water, the calcium ions in the carrier are slightly dissolved, causing the waste water to leak into the area 1, especially near the carrier where microorganisms are attached. Moreover, since ceramic has biocompatibility, it can maintain microbial activity at a high level due to the elution of calcium ions from the carrier.

Claims (1)

[Claims] Add at least 10% by weight of clay and 5 to 20% by weight of lime to the main ingredients, shirasu or fly ash, add a pore-forming agent, mold, and heat to a maximum temperature of 700 to 900℃.
Porous microbial carrier obtained by baking for 1 to 3 hours