JPH0819788A - Bacteria fixed electrode - Google Patents

Abstract

PURPOSE:To obtain a living body catalyst fixed electrode suitable for purifying waste water by a biological and electrochemical treatment from a container made of a porous substance, the conductor attached to the container and a plurality of the living body catalyst fixed conductive solids being in contact with the container. CONSTITUTION:A conductor 2 (e.g. carbon rod) is attached to a container 1 made of a porous substance composed of plastic and a large number of living body catalyst fixed conductive solids 3 are received in the container in an immovable or fluidized state. A carbonaceous material is used as a solid fixing a living body catalyst (e.g., nitrifying bacteria, denitrifying bacteria). The living body catalyst is fixed to the conductive solids 3, for example, by immersing conductive particles in an activated sludge slurry in the fixing of nitrifying bacteria and denitrifying bacteria and supplying a substrate (acetic acid) to the slurry to culture the slurry for several-ten several days. As a result, a living body catalyst fixed electrode suitable for purifying waste water by biological and electrochemical treatment can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biocatalyst-fixed electrode which can be suitably used for biological electrochemical treatment of groundwater, industrial wastewater and domestic wastewater.

[0002]

2. Description of the Related Art In a conventional biocatalyst-fixed electrode, a biocatalyst is fixed on a rod-shaped or plate-shaped conductive solid surface such as carbon or metal.

[0003]

The above-mentioned conventional electrodes have the following problems. That is, the biocatalyst may be peeled off due to the shearing force of the fluid when immersed in flowing water to be treated for actual water treatment. In addition, the amount of the biocatalyst immobilized is suppressed by the restriction due to the diffusion phenomenon of the substrate in the immobilization layer. Furthermore, if the amount of electrodes in the tank is increased to increase the amount of wastewater treated in the water treatment tank, the effective volume of the treatment tank decreases, and the reactor volume efficiency decreases due to a decrease in the reaction rate per unit volume of the reactor. I do. In addition, since the biocatalyst-immobilized layer is thin, oxidation and reduction by the biocatalyst cannot proceed simultaneously with the same electrode or the same reactor. Is low.

[0004]

The present inventors have conducted research with the aim of developing a novel biocatalyst-immobilized electrode that has solved the above-mentioned problems, and as a result, for example, have been able to place a plurality of granular biocatalyst-immobilized conductive materials in a porous container. By accommodating, it was found that the object was achieved, and the present invention was completed. That is, the electrode of the present invention comprises a porous material container, a conductor attached to the container, and a plurality of biocatalyst-fixed conductive solids. The fixed conductive catalyst is usually contained in a porous material container. However, a container containing the catalyst may be provided outside the porous material container and contained in both containers.

Next, the electrode of the present invention will be described in more detail. In the present invention, a plurality of solids to which a biocatalyst is to be fixed will be described. This solid needs to be a conductive substance, and can be used as an electrode normally, for example, a carbonaceous material,
Metal, stainless steel or the like is used. And a carbonaceous material is preferable from a practical point of view. The reason is that carbonaceous material has good affinity for living organisms and is porous, and it is particularly easy to fix a biocatalyst. For example, when used as an anode, oxygen and CO ₂ are generated, and CO ₂ is CO ₂ → HCO ₃ ^This is because it dissociates with -H ⁺ . The solid is preferably in the form of granules, but an appropriate size is used. And practically about 1mm ~
Those having a range of 100 mm are used.

As the biocatalyst fixed to the conductive material, an appropriate one is used according to the purpose. For example, nitrifying bacteria are used for nitrifying ammonia; denitrifying bacteria are used for reducing nitric oxide ions. Next, the biocatalyst to be fixed will be exemplified. Aerobic bacteria; Nitrosomonas, Nitrococcus, Nitorobac
ter; Pseudomonas, Bacillus, Alcaligenes, Microc
ocus Anaerobic bacterium; Acidgenic bacteria, Homoacetogeneric b
acteria, Methansproducing bacteria, Sulfate redu
cing bacteria, Parococcus, Bacillns, Psendomonas
,

An example of a method for fixing these biocatalysts to a conductive solid will be described below. For fixing nitrifying bacteria and denitrifying bacteria, conductive particles are immersed in activated sludge slurry or supernatant water obtained by centrifuging the activated sludge slurry, and a substrate (NO ₃ ⁻ , acetic acid, inorganic salt, etc.) is supplied, and several days to 10 to 10 Incubate for a day. In the present invention, the biocatalyst-fixed conductive solid is contained in a container made of a porous material. It is preferable that the container does not allow the contained solid to flow out, allows the processing liquid to pass freely, and is insulating.
For this purpose, for example, plastics, ceramics and the like are used. The larger the pore size of the container, the more practical it is as long as the solids such as particles contained in the container are not discharged. The size of the container is appropriately determined depending on the purpose of use of the electrode. Solids such as particles may be immobile in the container, but may also be fluidly filled. The filling volume is required to be at least about 50 when the case where solids such as particles are immobile is 100. If the packing is too loose, it may not function as an electrode. When the biocatalyst-fixed conductive solid is immovably stored in the container, the solids may be connected to each other by an appropriate means. Next, since it is an electrode, a connecting conductor is attached to the power source. The conductor must be fixed to the container. As the material of the conductor, known materials such as stainless steel and iron are practically used.

Although the shape of the container is not specified, a box shape is desirable for practical use. Next, the present invention will be described based on schematic explanatory drawings. FIG. 1 shows a standard microbial immobilized electrode of the present invention. In the figure, 1 is a porous container, 2 is a conductor attached to the container, and 3 is a biocatalyst-fixed conductive solid (particle) attached to the container. In FIG. 1, the conductive solid is immovably accommodated in a container. 2 and 3
Shows a state where biocatalyst-fixed conductive solids housed in a container are connected to each other. FIG. 2 shows an example in which the particles 3 are bonded to each other by a bonding agent at the contact points 4, and FIG. 3 shows the particles 3 in the connecting body 5 (the biocatalyst is fixed by the same substance as the particles)
An example where is provided. The electrode of the present invention is appropriately used as a cathode or an anode depending on the purpose. For example, the nitrifying bacterium of the present invention, the electrode of the present invention on which the denitrifying bacterium is fixed is used as an anode, and a normal electrode is connected as a cathode or a nitrifying bacterium, the microbial fixed electrode of the present invention on which the denitrifying bacterium is fixed is used as an anode, and the denitrifying bacterium is There is a method of using the fixed microorganism-fixing electrode of the present invention as a cathode.

[0009]

The biocatalyst-fixed conductive solid is used in a container made of a porous material, and is preferably granular, but its shape and size can be freely determined. Further, the specific surface area of the electrode can be freely changed. For example, when wastewater treatment is performed using the electrode of the present invention, when the wastewater contains many solids and suspensions, they are accumulated between the biocatalyst-immobilized conductive solids and the wastewater flow is blocked. However, it is easy to prevent the blockage by changing the size of the solid according to the situation of the drainage. In addition, since the microorganisms to be fixed can be freely selected, oxidation and reduction can be performed in the same tank.

[0010]

【Example】

Example 1 1. It is made of 100 mm long, 10 mm wide and 100 mm high, the hole diameter is 1-2 mm, and the area occupied by the hole is 90
%, And the following biocatalyst-fixed conductive particles were contained in a plastic container. Conductive particle diameter 2-3 m
m, material activated carbon, type of fixed biocatalyst Nitrifying bacteria, denitrifying bacteria, fixed amount of catalyst 400 mg, storage amount of the same particles (a) 70 g when immobilized (b) flow state ４０ 40 g Is made of carbon in the center of 80mm wide and 8mm long
A conductive material having a thickness of 0 mm and a thickness of 1 mm is attached. The specific surface area of this electrode is suitable for treating wastewater containing 15 cm ^{-1 and} particularly ammonia. Example 2 (a) Anode; length 100 mm, width 10 mm, height 100 m
m, the diameter of the hole is 2 to 3 mm, and the ratio of the hole is 90% of the total surface area.
m, length 80 mm, thickness 1 mm stainless steel plate attached, nitrifying bacteria and denitrifying bacteria were fixed in this container.
4 mm of activated carbon was accommodated. The amount of activated carbon contained is 70 g, and the amount of catalyst fixed on the activated carbon is 300 mg. (B) Cathode: A carbon rod having a length of 80 mm and a diameter of 8 mm was attached to the center of the plastic container similar to (a).
Activated carbon in which nitrifying bacteria and denitrifying bacteria were fixed as in (a) was accommodated in this container. The specific surface areas of both (a) and (b) are 12 cm ⁻¹ . Each of them is a packed bed type electrode, and as shown in FIG.
(B) apparatus provided with both electrodes is particularly Anmoniya, NO ₃ ^-, N
O ₂ ^- is suitable for the drainage containing process. In FIG. 4, reference numerals 6 and 6 'denote plastic containers. Each container is provided with a 2-3 mm hole over its entire surface. 7 is the above-mentioned carbon rod, and 8 is a stainless steel plate. Activated carbon is accommodated in both vessels, respectively. As shown in FIG. 4, both are connected and accommodated in a reaction vessel, and the wastewater to be treated, particularly ammonia, NO
₃ ^-, NO ₂ ^- Treatment of waste water containing, Anmoniya, NO
₃ ^- and NO ₂ ^- are removed. Embodiment 3 An apparatus shown in FIG. 5 will be described. 9 is 200m in diameter
m is a stainless steel container having a height of 200 mm. Reference numeral 10 is a porous plastic cylinder with a diameter of 5 mm, which is attached to the center of the stainless steel container and has a diameter of 5 to 6 mm, which occupies about 30% of the surface area. Reference numeral 11 denotes a carbon rod having a diameter of 2 mm provided at the center of the plastic cylinder. Between the porous plastic container and the stainless steel container, carbon particles having a denitrifying bacterium having a particle diameter of 8 mm are accommodated. As shown in the figure, a device in which the carbon rod 11 is electrically connected to the periphery of the stainless steel container is particularly suitable for treating wastewater containing NO ₃ ⁻ . The wastewater to be treated is contained in a stainless steel container.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a microorganism fixed electrode of the present invention.

FIG. 2 shows an example in which biocatalyst-fixed conductive particles are bound by a binder at a contact point.

FIG. 3 is an example in which a connector is provided between biocatalyst-fixed particles.

FIG. 4 is an explanatory view of an apparatus of the present invention according to a second embodiment.

FIG. 5 is an explanatory view of a device according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Porous substance container 2 Conductor 3 Biocatalyst fixed conductive solid 4 Contact between biocatalyst fixed conductive solids 5 Connector of biocatalyst fixed conductive solid 6 Plastic container 6 'Plastic container 7 Carbon rod 8 Stainless steel plate 9 Stainless steel container 10 Porous plastic cylinder 11 Carbon rod

Claims (7)

[Claims] 1. A microorganism-fixed electrode comprising a porous material container, a conductor attached to the container, and a plurality of biocatalyst-fixed conductive solids in contact with the container. 2. The microorganism-fixed electrode according to claim 1, wherein the biocatalyst-fixed conductive solid is contained in a porous material container. 3. The microorganism-fixed electrode according to claim 1, wherein the biocatalyst-fixed conductive solid is in the form of particles. 4. The microorganism fixed electrode according to claim 1, wherein the material of the container is plastics or ceramics. 5. The microorganism fixed electrode according to claim 1, wherein the container has a box shape. 6. The microorganism-fixed electrode according to claim 1, wherein the biocatalyst-immobilized conductive solid is immobilized in a container. 7. The microorganism-fixed electrode according to claim 1, wherein the biocatalyst-fixed conductive particles are contained in a container in a flowable state.