JPH022633B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a carrier for attaching microorganisms for use in a contact bed method, which is a method for the action of microorganisms on sewage in sewage treatment means based on a treatment method using microorganisms, particularly aerobic microorganisms. It is.

The fluidized bed method, which is one aspect of the contact bed method, is a wastewater treatment method in which microbial carriers to which microorganisms are attached are made to flow through wastewater to be treated by using convection of the wastewater, and the method uses a biological film per unit volume of wastewater. It is attracting attention because it can be produced in large quantities.

The fine plastic particles known as microbial carriers used in this fluidized bed method are foam-molded by mixing an inorganic material with a synthetic resin base material, and the surface is treated by corona discharge machining so that microorganisms can easily adhere to the surface of the carrier particles. There are things etc. In addition, in order to increase the adhesion surface area, the shape of the plastic particles is made into a hollow cylinder, and when the hollow cylinder is extruded,
The uneven pattern formed on the sliding surface of the extrusion die forms a large number of streak-like unevenness in the direction of the extrusion axis.

However, when such plastic particles are used, they absorb water and change their specific gravity over time, the formation of a film due to the attachment of microorganisms does not proceed smoothly, and the attached microorganisms tend to peel off. There is a drawback.

In view of the above-mentioned circumstances, the present invention provides a method for producing plastic particles, preferably porous plastic particles, which have extremely good adhesion of microorganisms and are difficult to peel off during the reaction, and which provide a method for producing plastic particles, preferably porous plastic particles, which have excellent adhesion with microorganisms and are difficult to peel off during the reaction. Manufacture of a contact material for sewage treatment, characterized in that an extruded plastic small-diameter columnar body is scratched on its outer periphery in an unsolidified state to form a large number of scratched and cleaved parts, and then cut into a required length. It is the law.

An embodiment of the method of the present invention will be described with reference to an apparatus shown in the drawings.

Crystalline resins such as polypropylene, high-density polyethylene, and low-density polyethylene, polyvinyl chloride,
A physical blowing agent such as butane or pentane or a chemical blowing agent such as a mixture of solid acid and carbonate is mixed with a synthetic resin such as an amorphous resin such as polystyrene, and the mixture is kneaded and melted in an extruder 1 to form an inner peripheral wall. Molten resin is extruded from a die 2 having a large number of streak-like irregularities and a hollow part in the center, and a small-diameter columnar body of foamed plastic is formed by forming a large number of streak-like irregularities in the axial direction on the circumferential surface. While continuously extruding and stretching, the material is passed through a water bath in a cooling water tank 5 via tension rolls 3, 3, 4, 4, and when the outer peripheral portion has started to solidify but the inside is in an unsolidified state, the brushing device 6 It passes between the upper brush roll 7A and the lower brush roll 7B to form a large number of scratch-like cleavages C, C... on the outer periphery of the small-diameter columnar body B (see FIG. 5), and then the cutting blade 9 of the cutting device 8 The foamed plastic particles 2 and 2 for sewage treatment are manufactured by cutting the particles to the required length.

As shown in FIGS. 2 and 3, the brushing device 6 has rotating brush rolls 7A and 7.
In B, a large number of steel wires 10, 10, . . . with a diameter of 0.2 mm to 0.8 mm are planted at intervals of about 0.5 mm to 1 mm, and the implant height is 5 mm to 30 mm.

In addition, as shown in the third diagram, the brush rolls 7A and 7B have an angle θ between a line 12 perpendicular to the rotation center axis 11 and an axis 13 in the stretching direction a, which is larger than zero degrees and smaller than 90 degrees. Set it like this.

The reason why the angle θ is 0° < θ < 90° is because the angle θ
When the temperature is zero, scratches are formed along the axial direction at the bottom of the extruded small-diameter columnar body, causing cracks. In other words, the valley bottoms of the streak-like unevenness are scratched by the steel bristles 10, causing cracks, and the angle θ is
If the angle θ is set to 90 degrees, the degree of formation of the scratch cleavage portion C is small, and since the rotation center axis 11 of the brush rolls 7A and 7B is parallel to the wire extension direction a, tearing occurs, and the angle θ is preferably 20 degrees. The angle should be between ゜ and 60゜.

In this way, the scratching by the brushing device 6 can form streak-like unevenness in areas other than the valley bottoms as in this embodiment.

Furthermore, the specific gravity of the plastic particles produced by the method of the present invention ranges from 0.79 to 0.79 by making them porous.
0.85, the maximum cross-sectional dimension d ₁ of the small diameter columnar body is 3 mm to 10 mm, and the length in the axial direction is 3 mm to 10 mm.

In addition, as in the above embodiment, when the tubular body has a large number of linear unevenness in the axial direction on the outer circumferential surface, the thickness of the thinnest part between the valley bottom of the linear unevenness part A and the inner peripheral surface is The length is set to 0.1 mm to 0.14 mm.

Furthermore, it is more preferable to take the following measures to prevent the cross section from deforming or buckling and cracking when cutting into the required length with the cutting device 8.

That is, as shown in FIG. 6, when cutting a small-diameter columnar foamed plastic that has been extruded and has streak-like irregularities formed on its outer periphery with a cutting blade in a direction intersecting the axial direction of the small-diameter columnar body, the cutting blade 14 is cut while being displaced in the longitudinal direction of the blade. Specifically, one end 14a of the cutting blade 14 is pivotally supported on the peripheral edge of the side surface of the rotating body 16 via a pin 15, and the vicinity of the other end 14b of the cutting blade 14 is slidably supported on the support 17. The support body 10 is configured to be able to swing around a support shaft 18 following the displacement of the cutting blade 14.
By means of such means, it is possible to prevent the small-diameter columns of foamed plastic from being deformed by cutting.

Furthermore, the means shown in Figure 6 prevents buckling and cracking during cutting when the small diameter columnar body is a tubular body and the outer peripheral surface is formed with various streak-like irregularities in the axial direction as shown in Figure 5. , more preferred.

In FIG. 1, the same effect can be obtained by moving the shaft 20 of the rotating body 19 to which the cutting blade 9 is attached every 1/4 cycle of the rotation of the rotating body 19 while the cutting blade 9 is in contact with the foamed plastic body. can be obtained.

In addition, as a means for scratching the outer peripheral part of the columnar body which is not solidified as a whole after extrusion, fine particles of 0.2 mm to 0.8 mm are placed outside the brush roll.
A roll in which inorganic, particularly metal, particles of mm size may be partially embedded in a face piece may be used, or fine inorganic particles may be sprayed onto a columnar body and collided with the columnar body, as in sandblasting.

Next, specific examples of the method of the present invention will be given.

Example Polypropylene pellets (MA-3 manufactured by Mitsubishi Yuka Co., Ltd.) were placed in an extruder 1 with a screw diameter of 40 mm,
Mix 0.07 to 0.5% by weight of organic acid and carbonate mixed blowing agent (Handrocellol, manufactured by Boehringer Ingelheim) to polypropylene.
The resin is heated and melted at 180° to 200°C, the diameter of the peaks of the streaky unevenness is 22 mmψ, and 30 streaky unevenness are formed, and the molten resin is extruded and foamed from the die 2 through the die 2. While being stretched, it is passed through the cooling water tank 5. The brushing device 6 scratches the outer periphery, and the cutting device 8 scrapes the outer periphery, and when the diameter of the crest becomes 3 mmψ and the outer circumferential surface starts solidifying, and the inside is still in an unsolidified state, the brushing device 6 scratches the outer periphery, and the cutting device 8 cuts the 3 mm length into pieces. Foamed plastic particles were produced as microscopic lengths.

In this case, the specific gravity of the foamed plastic particles is
0.790 to 0.85, and the angle θ in the brushing device 8 was set to 30 degrees.

In addition, in order to improve the adhesion state of the bacterial cells that form the biofilm and to prevent their detachment as much as possible during the reaction, consider the foaming ratio, the number and size of streak-like irregularities, the degree of scratching during brushing, etc. The optimum conditions shall be selected by

The method of the present invention not only makes it possible to increase the adhesion area by scratching and tearing required parts such as both end faces of the peripheral surface of plastic particles, but also makes it easy for microorganisms to adhere to the scratching and tearing parts. It becomes interlocked with the biofilm and is difficult to peel off during the reaction. FIG. 7 shows an enlarged microscopic photograph of the outer circumferential surface of the carrier for microorganism attachment obtained according to the present invention.

The present invention makes it possible to efficiently produce minute plastic particles having scratch-cleaved portions formed on at least the outer periphery without causing problems such as deformation, thereby significantly improving productivity.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an example of a manufacturing device to which the method of the present invention is applied, Fig. 2 is a front view showing the main parts of the brushing device, Fig. 3 is a plan view of the same, and Fig. 4 is a system diagram showing an example of a manufacturing device to which the method of the present invention is applied. FIG. 5 is an enlarged plan view of the main parts of the foamed plastic particles produced in this way, FIG. 6 is a perspective view showing the main parts of the cutting device, and FIG. 7 is an enlarged end view of the foamed plastic particles obtained by the present invention. This is a 34x magnified micrograph of a carrier for microbial attachment. DESCRIPTION OF SYMBOLS 1...Extruder, 2...Die, 5...Cooling water tank, 3, 4...Tension roll, 6...Brushing device, 7A, 7B...Brush roll, 8...Cutting device, A...Striped shape Irregularities, c... scratch cleavage,
D... Foamed plastic particles.

Claims (1)

[Claims] 1. Sewage treatment characterized in that a plastic small-diameter columnar body continuously extruded from an extruder is scratched at its outer circumference in an unsolidified state to form a large number of scratched and cleaved parts, and then cut into a required length. A method for manufacturing a carrier for attaching microorganisms.