JP5824960B2 - Microbe attachment carrier - Google Patents

Description

  The present invention relates to a microorganism adhesion carrier to which microorganisms for biological treatment of organic wastewater or the like are adhered.

Conventionally, it is known that biological treatment is effective as a treatment method for organic wastewater such as household wastewater and factory wastewater. Among them, the activated sludge method is most widely adopted.
In the activated sludge method, a carrier is immersed and disposed in a treated water tank into which activated sludge has been charged, microorganisms contained in the activated sludge are adhered to the surface of the carrier, and organic matter in waste water is decomposed by the adhered microorganisms. There is. Here, as a carrier, one using a fiber product is known. For example, in Patent Document 1, a backbone is composed of a warp and a weft, and a number of U-shaped loop wefts are formed on the backbone. A provided form of carrier is described. Patent Document 2 describes a carrier obtained by processing a woven fabric made of warp and weft into a tuft. Patent Document 3 describes a three-dimensional shape in which a sludge-attached yarn is arranged along a net-like core material.

Japanese Patent No. 3242363 Japanese Patent No. 3167151 Japanese Patent No. 3471310

However, the carrier of the form described in Patent Documents 1 and 2 takes time to manufacture. In addition, when immersed in a treated water tank, the amount of fibers per unit volume is small, so the amount of attached microorganisms is limited, and efficient biological treatment is difficult.
Moreover, although the thing of patent document 3 has much fiber amount per unit volume compared with the support | carrier of patent document 1 and 2, its manufacture takes very much effort.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a carrier for attaching microorganisms that can be easily manufactured, has a large amount of fibers per unit volume, and enables efficient biological treatment.

The carrier for attaching microorganisms of the present invention is a carrier for attaching microorganisms, which is immersed in a treated water tank into which activated sludge is charged in a membrane separation activated sludge treatment apparatus , and attaches microorganisms in the activated sludge. It consists of a dry-type nonwoven fabric comprised with the fiber of the acrylic polymer which has 50 mass% or more.
The nonwoven fabric preferably has a basis weight of 60 to 1000 g / m ² .
The nonwoven fabric preferably has a thickness of 0.5 to 30 mm.

  ADVANTAGE OF THE INVENTION According to this invention, the support | carrier for microorganisms adhesion which can be manufactured simply and has many fibers per unit volume and can perform an efficient biological treatment can be provided.

It is a top view which shows an example of the support | carrier unit which comprised the support | carrier for microorganisms adhesion of this invention. It is a block diagram which shows an example of the membrane separation activated sludge processing apparatus provided with the support | carrier unit of FIG. It is a graph which shows the relationship between the elapsed days which immersed the support | carrier for microorganisms adhesion in the processing water tank in the Example, and the mass increase in that case.

Hereinafter, the present invention will be described in detail.
The carrier for attaching microorganisms of the present invention is a sheet-like material composed of a nonwoven fabric composed of acrylic polymer fibers, and is immersed in a treated water tank into which activated sludge for biologically treating organic wastewater is placed. And attaches microorganisms in activated sludge. Examples of the treated water tank include an activated sludge tank in which only biological treatment with activated sludge is performed, and a membrane separation activated sludge tank in which a separation membrane such as a hollow fiber membrane is also immersed, and membrane treatment with a separation membrane is performed together with biological treatment. It is done.

  As the acrylic polymer, one having 50% by mass or more of acrylonitrile units is used. Fibers (acrylic fibers) made of such an acrylic polymer are suitable as a material for a carrier for attaching microorganisms because they are superior in adhesion to microorganisms compared to other fibers.

“Having 50% by mass or more of acrylonitrile units” means that the ratio of acrylonitrile in the monomer for producing the acrylic polymer is 50% by mass or more.
Moreover, the preferable upper limit of an acrylonitrile unit is 97 mass%.

The acrylic polymer has 50% by mass or more of acrylonitrile units, and can have a unit composed of an unsaturated monomer copolymerizable with acrylonitrile in a range of 50% by mass or less.
The unsaturated monomer copolymerizable with acrylonitrile is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, derivatives thereof, vinyl acetate, acrylamide, vinyl chloride, and vinylidene chloride. Depending on the purpose, ionic unsaturated monomers such as vinylbenzene sulfonic acid soda, methacrylic sulfonic acid soda, and acrylamidomethylpropane sulfonic acid soda can be used as unsaturated monomers copolymerizable with acrylonitrile.

  The polymerization method of the acrylic polymer is not particularly limited, and for example, a usual suspension polymerization method or solution polymerization method can be adopted.

The nonwoven fabric is not particularly limited as long as it is composed of such acrylic polymer fibers, but the nonwoven fabric is required to have durability in a treated water tank as a microorganism-adhering carrier. A dry nonwoven fabric produced through the process is preferred.
A dry nonwoven fabric is obtained by carding and laminating staple fibers having a crimped shape to form a web and binding the web. As the method for binding the web, a method selected from the spunlace method, the needle punch method, and the stitch bond method is preferable because the fiber can be exposed as much as possible on the surface of the nonwoven fabric.

  The manufactured nonwoven fabric may be subjected to arbitrary processing such as calendering, embossing, raising, and hot pressing as necessary.

The basis weight and thickness of the nonwoven fabric are related to the amount of microorganisms when immersed as a carrier for microorganism adhesion, strength, durability, etc., and can be adjusted according to the quality of the wastewater in the treatment water tank, treatment conditions, The basis weight is preferably 60 g or more per 1 m ² . When the basis weight is 60 g or more, it is possible to exhibit sufficient strength and durability even when a physical load such as aeration is applied by being immersed in a membrane separation activated sludge tank as a carrier for attaching microorganisms, Microorganisms can be sufficiently adhered.
On the other hand, since many microorganisms are easily attached and held on the surface of the nonwoven fabric, if the basis weight is too high, the fibers inside the nonwoven fabric are not sufficiently utilized for the adhesion of microorganisms. If the basis weight is too high, the weight of the nonwoven fabric increases due to sludge and moisture adhering to the nonwoven fabric. From such a viewpoint, the basis weight per 1 m ² is preferably 1000 g or less, and more preferably 300 g or less in consideration of the processability of the nonwoven fabric and the efficiency of adhesion of microorganisms.

  If the thickness of the nonwoven fabric is too thin, the strength and durability may be reduced, and the amount of microorganisms attached may be insufficient. Moreover, when too thick, workability will fall, for example, when manufacturing a carrier unit like the after-mentioned, it may become difficult to process. Therefore, the thickness of the nonwoven fabric is preferably 0.5 mm or more and 30 mm or less, and more preferably 20 mm or less from the viewpoint of workability.

The most preferred nonwoven is a basis weight 100 to 500 g / ^{m 2} per 1 m ^2, is intended thickness of 1 to 10 mm. If it is such a nonwoven fabric, microorganisms can fully adhere and it is excellent also in intensity | strength, durability, and workability.

In order to adjust the basis weight of the nonwoven fabric, for example, fiber carding may be performed with a roller card, and the obtained card web may be folded and laminated in parallel until a predetermined basis weight is obtained.
In addition, in order to adjust the thickness of the nonwoven fabric, a predetermined thickness may be obtained by performing needle punching with a punch needle on the laminated layers as described above. Moreover, you may further adjust so that it may become predetermined thickness by hot-pressing the obtained nonwoven fabric as needed.

  Such a non-woven fabric may be immersed in a treated water tank such as an activated sludge tank or a membrane-separated activated sludge tank as a sheet-like microorganism adhesion carrier as it is, but is combined with a base cloth in order to increase strength and durability. It may be immersed in the form of a laminated body. Moreover, when laminating | stacking with a base fabric in this way, since it is preferable from a viewpoint of microorganisms adhesion that the nonwoven fabric demonstrated above is located in the surface, the structure which clamped the base fabric with two nonwoven fabrics is preferable.

As a method of manufacturing a laminate in which a base fabric is sandwiched between two nonwoven fabrics, first, fiber carding is performed with a roller card, and the obtained card web is folded and laminated in parallel to obtain a web having a desired basis weight. Get. What is necessary is just to perform needle punching with a punch needle with respect to what prepared two sheets of webs obtained in this way, and pinched | interposed the base fabric between them, and should just make it a desired thickness.
Examples of the base fabric include spunbonded nonwoven fabrics and woven fabrics made of fibers that are hardly decomposable to water and organisms, such as polyester fibers, polypropylene fibers, polyamide fibers, and acrylic fibers.

Alternatively, the microorganism-adhering carrier may be immersed in the treatment water tank in the form of a carrier unit in which a microorganism-adhering carrier comprising a nonwoven fabric is combined with a support that supports the microorganism-adhering carrier.
As the carrier unit, for example, as shown in FIG. 1, when the microorganism-adhering carrier 1 made of a rectangular non-woven fabric and the microorganism-adhering carrier 1 are immersed in the treatment water tank, they are provided at the ends that are the upper end and the lower end. A carrier unit 3 composed of a pair of elongated supports 2 is mentioned. Further, a similar support may be provided on the laminate in which the above-mentioned base fabric is laminated on a carrier for attaching microorganisms made of nonwoven fabric to form a carrier unit.

  Since the carrier for attaching microorganisms described above is made of a nonwoven fabric, it can be easily manufactured. Moreover, since the amount of fibers per unit volume is large, the amount of microorganisms attached when immersed in a treated water tank is increased, and an efficient biological treatment can be performed.

Hereinafter, the present invention will be specifically described with reference to examples.
[Examples 1 to 3]
As the acrylic fiber, Bonnell “H815BRE2.2T51” manufactured by Mitsubishi Rayon Co., Ltd. was used. Carding was performed on this fiber with a roller card, and the resulting card web was folded in parallel and laminated. Next, needle punching with a punch needle was performed on the obtained web. Furthermore, in order to suppress the thickness, in Example 3, hot pressing was performed to obtain nonwoven fabrics having the basis weight and thickness shown in Table 1.
The basis weight of the nonwoven fabric was adjusted by the number of layers when the card webs were folded in parallel and laminated, and the thickness was adjusted by the conditions of needle punching and the presence or absence of hot pressing.

  Next, as shown in FIG. 1, a pair of supports 2 is provided on a microorganism-adhering carrier 1 made of nonwoven fabric to form a carrier unit 3, and this carrier unit 3 is placed in a membrane separation activated sludge treatment apparatus as shown in FIG. It was immersed in the treated water tank (activated sludge tank) 10 and fixed with the fixture 4.

The membrane separation activated sludge treatment apparatus shown in FIG. 2 includes a treatment water tank 10, a membrane unit 20 immersed in the treatment water tank 10, an air diffuser 30 that diffuses into the membrane unit 20, and a membrane unit 20. A connected filtration pump 40, a control device 50 that controls the operation of the filtration pump 40 and the air diffuser 30, and a supply line 60 that supplies raw water to be treated to the treated water tank 10 are provided.
The activated sludge concentration in the treated water tank 10 was controlled so that the solid content concentration MLSS was between 8,000 and 10,000 mg / L. Moreover, the amount of diffused air was controlled so that the dissolved oxygen concentration (DO) in the treated water tank 10 was between 0.5 and 1.0 mg / L. As raw water to be treated, domestic wastewater having a biological oxygen demand (BOD) concentration of 150 to 200 mg / L is used, and this raw water is subjected to a hydrodynamic residence time of 3 hours in the treated water tank 10. And acclimated for 3 months under the above conditions.
Then, the support | carrier unit 3 was immersed in the activated sludge of the treated water tank 10 which was adapted, and it fixed as mentioned above.

After the immersion, the carrier unit 3 was taken out of the treated water tank 10 every predetermined number of days, and its mass was measured. The graph of FIG. 3 shows the relationship between elapsed days and mass increase.
The mass increase is obtained by dividing the value obtained by subtracting the mass of the carrier unit 3 before the immersion from the mass of the carrier unit 3 after the immersion by the area of the carrier (nonwoven fabric) 1 for attaching microorganisms, and per unit area (per 1 cm ² ) Value. The increase in mass corresponds to the amount of activated sludge attached.

As shown in FIG. 3, it was understood that the microorganism-adhering carrier of each example increased in mass with the elapsed days, and the microorganisms adhered well.
Further, in Examples 1 and 2 in which the basis weight of the nonwoven fabric was 60 g / m ² or more, the mass increased, that is, the amount of attached microorganisms also increased.

  1 Microorganism attachment carrier (nonwoven fabric)

Claims (3)

A microbial attachment carrier that is immersed in a treated water tank into which activated sludge is charged in a membrane separation activated sludge treatment apparatus , and adheres microorganisms in the activated sludge,
A microorganism-adhering carrier comprising a dry nonwoven fabric composed of acrylic polymer fibers having 50% by mass or more of acrylonitrile units. The non-woven fabric, basis weight is 60~1000g / ^{m 2,} microbial attachment carrier according to claim 1.   The microorganism-adhering carrier according to claim 1 or 2, wherein the nonwoven fabric has a thickness of 0.5 to 30 mm.

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