JPS6250200B2 - - Google Patents

Description

[Detailed description of the invention]

In the present invention, when manufacturing a bioimmobilized filter bed, magnetic powder is contained in plastic and used as a filter bed, thereby increasing the adhesion of microorganisms compared to conventional filter beds and reducing wastewater. The present invention relates to a method for treating organic wastewater using a biologically fixed filter bed that can be efficiently treated. Methods for biologically treating organic wastewater are widely used today. Examples include an activated sludge method in which microorganisms are propagated in wastewater to decompose organic matter, and a method using a bioimmobilized filter bed in which microorganisms are grown on a filter bed and brought into contact with wastewater to decompose organic matter. The method using a biologically fixed filter bed requires less site area than the activated sludge method, and is easier to manage. etc. are known. However, conventional methods that use plastic, activated carbon, gravel, etc. as filter beds have the disadvantage that microorganisms are difficult to settle on these filter beds, and the attached microorganisms are easy to detach. There were problems such as not being able to process the data. Therefore, the present inventors succeeded in preventing the detachment of microorganisms and making it possible to easily treat organic wastewater by using a magnetized filter bed made of plastic such as vinyl chloride, polyethylene, or polypropylene containing magnetic powder. That is, the present invention is a method for treating organic wastewater using a magnetic plastic obtained by mixing magnetic powder with plastic, molding it, and magnetizing it as a biological fixation filter. Because it uses a filter bed with very good filtration, wastewater treatment using microorganisms is also effective, and compared to the conventional biological treatment method using a filter bed, it is much more effective.
The removal rate of BOD and COD is high, and the treated water
It is possible to lower BOD and COD values. The magnetic plastic used for the filter bed of the present invention is
It can also be manufactured by kneading a magnetic material into plastic such as polyethylene, polypropylene, vinyl chloride, etc., molding it, and then magnetizing it.
More preferably, the material is foamed using a foaming agent, molded, and then magnetized to form a porous plastic. When the decomposition temperature of the decomposable foaming agent is lower than the molding temperature, the plastic, magnetic powder, and foaming agent are mixed in advance, molding and foaming are performed simultaneously, and then magnetized to create a ferromagnetic porous material. A plastic can be obtained, but if the decomposition temperature is higher than the molding temperature, a magnetic plastic can also be obtained by molding the mixture, followed by foaming and then magnetization. Furthermore, when using a solvent-based blowing agent, the plastic and magnetic powder are mixed in advance, and the blowing agent is press-fitted during molding to perform molding and foaming, which is then magnetized to obtain magnetic plastic. According to the method, a product with a high foaming ratio can be obtained. In addition, a product with a higher expansion ratio can be obtained by further radiation crosslinking or by adding a crosslinking agent to the plastic. Additionally, surfactants such as stearic acid, oleic acid, lauric acid,
Linoleic acid, palmitic acid, and their salts (Na, Li, K, Ca, Mg) may be added. Examples of the molding method include extrusion, calendering, conveyor belt casting, and the like. Examples of blowing agents include decomposition blowing agents such as sodium bicarbonate, ammonium carbonate, azobisisobutyronitrile, diazoaminobenzene, N・N′-dimethyl-N・N′-dinitrosoterephthalamide, and solvent-based foaming agents. Examples of the agent include propane, butane, heptane, hexane, benzene, methylene chloride, trichlorofluorinated methane, and the like. Plastics used in the present invention include polyvinyl chloride, polyethylene, polypropylene, ethylene-vinyl acetate copolymer resin, polystyrene,
Examples include, but are not limited to, polyurethane, ABS resin, polyamide, polyvinyl formal, cellulose acetate, acrylic resin, epoxy resin, phenolic resin, urea resin, and silicone resin. Examples of the magnetic powder used in the present invention include magnetite, magnesium ferrite, nickel ferrite, manganese ferrite, cobalt ferrite, zinc ferrite, barium ferrite, strontium ferrite, and lead ferrite. The amount of magnetic powder contained in the plastic is generally 1 to 50%, but preferably 20 to 50%.
It is 30%. However, it is not limited to the above range as long as plastic molding is possible. The magnetic plastic produced as described above is obtained in the form of a sheet or granules, and can be used in various ways, such as a filter bed in the rotating disk method, a block or flat filter bed in the trickling bed method, and a fixed bed in the catalytic oxidation method. It is used as a filter bed in biological treatment methods, and microorganisms are implanted on it to treat organic wastewater. In order to implant microorganisms onto magnetic plastic, the wastewater is allowed to come into contact with the magnetic plastic for a certain period of time until the microorganisms in the wastewater propagate on the magnetic plastic under the same conditions as the wastewater treatment described below. It is possible. The treatment of organic wastewater using magnetic plastic on which microorganisms have been implanted as a filter bed is carried out according to conventional operating methods such as the rotating disk method, the trickling filter method, and the catalytic oxidation method. For example, in a method using a rotating disk processing apparatus, a sheet-like magnetic plastic is used for the rotor blade, and the processing is carried out by bringing it into contact with water under normal conditions of rotational speed and water inflow rate. In the trickling filter method, granular magnetic plastic (diameter: 1 to 10 cm) is tightly packed into a layer and wastewater is allowed to flow over the layer. A microbial film is formed on the surface of the magnetic plastic, which purifies the wastewater. Ru. Examples will be explained below. Example 1 A disk containing 20% magnetite using polyethylene as plastic (thickness 1.2 cm x diameter 100 mm)
cm) and magnetized to obtain a biofixed filter bed. A treatment experiment for organic wastewater was conducted using this filter bed using the rotating disk method. In addition, after one week of continuous operation, it was observed that a biofilm grew on the disk. Measurements of the treated water were carried out for three days after one month had passed since the start of operation. Sample sampling was performed at 3:00 p.m. The raw water composition of actual wastewater is shown in Table 1, and the experimental conditions are shown in Table 1.
2, the processing results are shown in Table 3.

【table】

【table】

[Table] Comparative Example 1 A treatment experiment similar to that in Example 1 was conducted using a rotating disk method using a polyethylene bioimmobilized filter bed manufactured without containing magnetic powder. The experimental conditions are the same as in Table 2 of Example 1.
Table 4 shows the raw water composition of actual wastewater. Although there was a slight difference in date and time from Example 1, there was no major change in the raw water composition. The treatment results are shown in Table 5.

【table】

【table】

[Table] Example 2 Using vinyl chloride resin as plastic,
A magnetic bioimmobilized filter bed (disc: 1.2 cm thick x 100 cm diameter) containing 20% zinc ferrite was manufactured. Experiments similar to those in Example 1 were conducted using this filter bed using the rotating disk method. Table 6 shows the raw water composition of actual wastewater, and Table 7 shows the treatment results.
Shown below. Note that the experimental conditions are the same as in Table-2.

【table】

[Table] Example 3 A filler having a diameter of 5 cm was produced using polypropylene as plastic and containing 30% barium ferrite. This magnetized filler was used in a trickling filter, and operation was continued for one week. After the growth of biofilm was observed on the filter, a biological treatment experiment was conducted. Measurements of the treated water were carried out for 3 days, one month after the start of operation. The raw water composition of actual wastewater is shown in Table-8, and the experimental conditions are shown in Table-8.
9, and the processing results are shown in Table 10.

【table】

【table】

[Table] Comparative Example 2 As a comparison with Example 3, a filler was produced using only polypropylene, and a biological treatment experiment was conducted using a trickling filter under the same conditions. The raw water composition is shown in Table 11, and the treated water is shown in Table 12.

【table】

[Table] Example 4 Polyethylene was used as the plastic, containing 15% cobalt ferrite powder, and 1% azodicarbonamide was used as the blowing agent.
A ~50 mm expanded filler was prepared and magnetized. The obtained filler was used in a trickling filter, and operation was continued for one week. After the growth of biofilm was observed on the surface of the filter, a biological treatment experiment was conducted. Measurements of the treated water were carried out for 3 days, one month after the start of operation. The raw water composition of actual wastewater is shown in Table 13, the experimental conditions are shown in Table 14, and the treatment results are shown in Table 15.

【table】

【table】

[Table] Comparative Example 3 As a comparison with Example 4, polyethylene was used as the plastic, containing 15% cobalt ferrite powder, and 1% azodicarbonamide was used as the foaming agent, and foamed with a diameter of 40 to 50 mm. A filler was produced. The obtained filler was subjected to a biological treatment experiment in the same manner as in Example 4. The raw water composition of actual wastewater is shown in Table 16, the experimental conditions are shown in Table 17, and the treatment results are shown in Table 18.

【table】

【table】

【table】

Claims (1)

[Claims] 1. The magnetic plastic obtained by mixing magnetic powder with plastic, molding and magnetizing it is used as a bioimmobilized filter, and the bioimmobilized filter on which microorganisms have been implanted is brought into contact with organic wastewater. A method for treating organic wastewater characterized by removing organic matter from the organic wastewater.