JPH0812461A - New carbon coated porous material and high-quality water treating method using the same porus material - Google Patents

Abstract

PURPOSE:To extremely reduce COD concentration of treated water of river and highly treated water of sewerage by immersing a porous substance obtained by blowing kaolln, etc., in a solution obtained by dissolving a carbohydrate compound in diluted sulfuric acid, drying/heat-treating the resulting substance to give a carbon coated porous substance, proliferating a microorganism on the porous substance and carrying out waste water treatment. CONSTITUTION:Kaolin, etc., are added to water to give a suspension, which is mixed with foams generated by introducing air into an aqueous solution of a surfactant, put in a mold, dehydrated, dried and baked at 500-650 deg.C to give an unglazed porous molded article. The porous molded article is immersed in an aqueous solution of a carbohydrate such as sugar in sulfuric acid (in the volume ratio of 1 water: 0.5-3 sulfuric acid), taken out and dried. The prepared material is heat-treated at 300-400 deg.C. In order to carry out water treatment by using the molded article, the molded article is immersed in water in an aerating tank before the use and made into a state in which a microorganism is taken in the molded article. Impure water having 2-5ppm calculated as COD is made into treated water having 1ppm COD.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel carbon-coated porous material and a method for advanced water treatment using the same. The target water to be treated here is
This refers to the tertiary treated water before tap water for sewage treatment and drainage from sewage treatment plants.

[0002]

2. Description of the Related Art Water-soluble impurities are contained in treated water obtained by subjecting water taken from rivers to aerobic aeration, coagulation and sedimentation, activated carbon, and tertiary treated water just before being discharged at sewage treatment plants. It is contained in the range of 2 to 5 ppm or more.

Conventionally, in order to use such water as tap water or tap water, it is sterilized by adding a chlorine-based sterilizing agent and supplied to users.

However, in a state of containing 2 to 5 ppm of COD equivalent impure organic matter, the added sterilizing chlorine is preferentially consumed by these organic matter, and a large amount of chlorine is required to achieve the original purpose.

Further, the reaction between chlorine and organic matter is mainly carried out in the piping line, and the reaction product adheres to the piping as scale and interferes with the flow of water.

Further, since the amount of added chlorine increases, various side reactions are carried out to produce trihalomethane, which is well known as a carcinogen. In addition, the water used as tap water is required to have a chlorine concentration of 0.1 ppm at the faucet of the end user, and it is necessary to add more chlorine to maintain this.

As described above, it has been demanded that the water to be subjected to the chlorine sterilization treatment should contain as little COD-converted impure water-soluble organic matter as possible, preferably 1 ppm or less.

[0008]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The inventors of the present invention have diligently studied the ultra-high-level water treatment method, which can reduce the content of impure organic substances in terms of COD to a minimum and consume less chlorine. By performing water treatment using a substance, microorganisms propagate at high density in the porous substance to decompose organic impurities, and the COD conversion value is 1 p
I learned that it can be processed until it becomes pm or less.

Further, it has been found that the porous material preferably has fine pores which are not closed and are wholly connected. In addition, such a porous substance absorbs bubbles obtained by foaming a surfactant into a suspension of kaolin, etc., and then, after molding, drying and firing, the porous substance is dissolved in hydrous carbon compounds in dilute sulfuric acid. It was found that it can be manufactured by immersing in the above liquid, drying and heating.

Therefore, an object of the present invention is to provide a river-treated water and advanced sewerage treatment containing the carbon-coated porous material thus obtained and 2-5 ppm of COD-equivalent organic impurities using the porous material. It is another object of the present invention to provide an advanced water treatment method using a microbial high-density breeding carbon-coated porous substance that reduces the content of organic impurities until the content of organic impurities becomes 1 ppm or less in terms of COD.

[0011]

The carbon-coated porous material of the present invention can be produced by the following method. That is, kaolin and water are added to a container with a stirrer to form a suspension, and then a foam generated by sucking air into a surfactant aqueous solution by a foaming machine is added and mixed, and then a mold is prepared. Place in a container and let it stand for dehydration, remove from the mold and dry (ventilation, 100 ° C), and then 500-650 ° C.
Calcination is performed to obtain a biscuit-like porous molded product.

The porous molded article was dipped in a liquid in which a hydrous carbon compound (carbohydrate) such as sugar was dissolved in sulfuric acid (water 1: 0.5 to 3 (volume ratio of sulfuric acid)), taken out and dried to obtain a surface. A porous molded product to which sulfuric acid and carbon are attached is obtained.

In this case, the solution of the hydrous carbon compound dissolved in sulfuric acid is prepared by gradually adding an aqueous sulfuric acid solution to a saturated solution of the hydrous carbon compound, and a sulfuric acid content is usually added to 1 part by weight of the hydrous carbon compound. As a conversion, 0.2 to 1 part by weight is used.

This impregnated porous molded product having sulfuric acid and carbon adhered to its surface is heat-treated at 300 to 400 ° C.,
SO ₂ and C generated by reacting sulfuric acid with carbon
It is produced by coating the carbon layer on the surface of the porous molded article with a gas having pores of mμ order by a gas such as O ₂ .

When water treatment is carried out using the carbon-coated porous material produced in this manner, prior to its use, the water in the aeration tank is porous as a pretreatment step for the raw water to be treated (water to be treated). It is preferable to immerse the substance in a state where microorganisms are taken into the body, and the microorganisms inhabiting the porous substance are COD (BOD) components in the raw water unless poisonous substances are mixed into the treated raw water. It can be semi-permanently used as a nutrient source by continuing breeding.

It is possible to use the carbon-coated porous material in a dry state in a tower without using the step of incorporating microorganisms into the body, but in this case, it takes 2-3 months as a fitting period.

As a water treatment method, an ordinary packed tower having a packing material tray at the bottom is filled with the porous substance of the present invention. Raw water (water to be treated) is passed through while exposing the air from under the saucer.

Although the speed at which water flows is related to the COD concentration of raw water, it is desirable that the SV (space velocity) is in the range of 0.1 to 1, and preferably in the range of 0.3 to 0.5. .

The size of the packed tower varies depending on the amount of treated water, but a small one may be made of steel plate or synthetic resin, but a large one is preferably made of concrete pool.

By carrying out such a treatment, water containing 2 to 5 ppm of COD conversion impure organic matter is converted into 1% COD conversion.
High-purity treated water of ppm or less can be used.

The carbon-coated porous material of the present invention can be used not only for the above-mentioned water treatment but also for flue gas desulfurization, removal of organic matter from organic matter-containing gas, and use as a porous electrode.

Next, the method for producing the carbon-coated porous material of the present invention will be described in more detail. The carbon-coated porous material according to the present invention forms a first-stage substrate by using bubbles generated by sucking air into a surfactant aqueous solution in a liquid obtained by suspending kaolin or the like in water. As such, kaolinite-based, is a generic term for silica-alumina-based minerals called by the name of halosite, etc., if plasticity is generated by kneading with water, and if it exhibits appropriate strength by drying, there is no particular limitation. Absent.

Further, the surfactant used for generating bubbles is cationic, anionic, nonionic or the like without any special restriction, and detergents used at home can be used.

A base material made of these compositions is put into a mold and molded, but the shape is not particularly limited, and any shape such as a cylindrical shape, a cylindrical shape, a saddle shape, a spherical shape, a plate shape, or an indefinite shape can be used. From the viewpoint of use, it is preferable to use a cylindrical or spherical shape.

After the molded product is removed from the mold, it is dried and fired to give a bisque-like strong product.

A carbon coating is applied to the bisque-fired porous molded product thus obtained, which is carried out by immersing it in a hydrous carbon compound, for example, an aqueous sulfuric acid solution such as sugar, followed by drying and heat treatment. .

Examples of sugars and the like used here include dense sugars represented by brown sugar, brown sugar, regenerated sugar, dense sugars generally called sugar, and Wasanbon sugar, which is an intermediate thereof. The water-containing carbon compound used in the present invention is not particularly limited as long as it is soluble in water, and soluble starch, glucose or the like can be used in addition to sugar.

The sulfuric acid is preferably dilute sulfuric acid, preferably water 1: sulfuric acid 0.5 to 3 (volume ratio), but a small amount of other mineral acid containing a sulfuric acid content of 10% or more. A mixed acid containing, for example, can also be used.

[0029]

The function is to treat water that contains impure organic matter at a concentration of 2 to 5 ppm in terms of COD and is good as ordinary water treatment until it reaches 1 ppm or less. The details of its removal action are unknown. However, it is hard to think that it is simply removed by adsorption, the porous substance of the present invention packed in the packed column retains the activity semipermanently, and the decomposed and fixed organic component is separated from the porous substance as a granular solid substance. Therefore, it is considered that the main part of this removing action is due to microorganisms.

In the step of decomposing organic matter, first, the organic substance in the raw water (water to be treated) is adsorbed and fixed on the carbonaceous material on the surface of the porous substance, and this is consumed by the microorganisms growing in the porous substance. It is considered to be a thing.

The consumption by the microorganisms and the adsorption by the carbon are repeated, and the sludge produced as a result of the consumption by the microorganisms is discharged from the porous substance as a water-insoluble granular solid substance, and is removed from the system without recontaminating the water. Taken out.

[0032]

The present invention will be described in more detail with reference to the following examples.

Example 1 Production Method of Carbon-Coated Porous Material To 1 part of kaolin was added 1.5 parts of water, and the mixture was sufficiently stirred with a stirrer to form a mud. Bubbles created by a foaming machine using a cationic surfactant were injected into this while stirring, and the total volume was made 2.5 times as large as before injection.

This was transferred to a molding frame, allowed to stand for one day and night, and then dried at about 100.degree. Then about 600 in an electric furnace
About 40W × 60L × 10H
It was cut into a shape of (mm) to obtain an unfired porous molded product.
(Observation with a microscope revealed that the pore size was 10-400.
It had a micron distribution. ) Next, carbon coating is performed.

To 10 parts by weight of sucrose, 4 parts by weight of water was added and dissolved, and to this was gently added 4.5 parts by weight of 50% diluted sulfuric acid, and the mixture was stirred and mixed well. The above-mentioned bisque-fired porous molded article was dipped in this, sufficiently impregnated with the liquid, and then taken out and dried at 80 to 100 ° C. Replace with nitrogen, about 35
The mixture was allowed to stay in an electric furnace heated to 0 ° C. for about 30 minutes to cause a reaction between sulfuric acid and carbon to obtain a carbon-coated porous material.

This carbon-coated porous material has not only its surface but also its pores all carbon-coated, and has adsorption activity.

Example 2 Water Treatment Test A water treatment test was conducted using the water tank 1 shown in FIG.
The porous material produced in Example 1 was immersed in sludge taken out from the aeration tank for test water for one day and night, and then filled in the second filling material tank. This filling material tank is divided into two tanks, and three diffusing pipes are provided at the bottom of each tank so that air can be sent. Test water is supplied from 4 and transferred to the next tank through the slit below the partition plate. The aerated air can move freely through the slit above the partition plate. From 5, the air and the treated water are mixed-phase flow and discharged out of the tank. A "weight" 6 with a rubber packing was placed on the upper part of the liquid / gas outlet pipe 5 so that the pressure in the tank was about 20 KPa.

Aeration and liquid passing conditions in the water treatment test are as follows.

Aeration rate SV = 10 Water flow rate SV = 0.35 Using the above water flow tank, COD concentration (JIS K0102
Aeration treatment of several ppm of river water (measured by the factory drainage test method) A water treatment test was performed on the supernatant. The results of the test for 3 months are shown in the table below.

[0040]

[Table 1]

As a result of testing for one year, microbial colonies were found to be formed on the surface of the packing material tank, and many colonies were formed between the packing materials.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a water tank used in the water treatment method of the present invention.

[Explanation of symbols] 1 water treatment device main body (water passage tank) 2 filling material tank 3 diffuser pipe 4 raw water (untreated water) inlet 5 treated water / gas outlet pipe 6 pressurizing weight 7 perforated plate

Claims (2)

[Claims] 1. A porous substance obtained by blowing foam foamed with a surfactant into a suspension of kaolin or the like, molding, drying and firing the foam, and dissolving hydrous carbon compounds in diluted sulfuric acid. A carbon-coated porous material obtained by immersing in a liquid that has been dried, drying and heating. 2. The carbon-coated porous material according to claim 1, which uses a fixed bed in which microorganisms are propagated at high density,
An advanced water treatment method in which the COD concentration is extremely lowered by passing the COD-containing treated water of several ppm concentration through the fixed bed.