KR100561182B1 - High strength multi-lumen type hollow fiber membrane for waste water treatment in MBR system - Google Patents

Abstract

The present invention relates to a high-strength multi-tubular hollow fiber membrane for wastewater treatment applied to an MBR system, and more particularly, a bundle of reinforce filament-yarn made of long fibers of polymer filament is embedded in the inner center of the hollow fiber. A multi-lumen structure is formed around a bundle of reinforcing fiber bundles to solve mechanical strength problems such as breakage or cutting of hollow fiber membranes due to external physical impact. High-strength, multi-tubular hollow, useful for wastewater treatment in membrane bioreactor (MBR) systems, as the diameter of hollow fiber membranes due to the reinforcing fibers and the resulting effective surface area reduction per unit volume can be minimized to maximize membrane permeation efficiency. It's about the desert.

Reinforcement fiber, multi-lumen structure, high strength multi-tubular hollow fiber membrane for water treatment, membrane bioreactor (MBR)

Description

High strength multi-lumen type hollow fiber membrane for waste water treatment in MBR system

Figure 1 shows a schematic view of a high strength multi-tubular hollow fiber membrane prepared in Example 1 according to the present invention.

[Description of Signs for Main Parts of FIG. 1]

1. reinforce filament-yarn 2. lumen

The present invention relates to a high-strength multi-tubular hollow fiber membrane for water treatment and a method for manufacturing the same, and more particularly, a reinforce filament-yarn made of long fibers of polymer filaments is embedded in the inner center, and a plurality of tubes By forming a multi-lumen structure surrounded by (lumen), to solve the mechanical strength problems such as breakage or cutting of the hollow fiber membrane due to external physical impact and at the same time, the diameter of the hollow fiber membrane due to the intrinsic of the reinforcing fiber The present invention relates to a high-strength, multi-tubular hollow fiber membrane for water treatment, and a method of manufacturing the same, which can maximize the permeation efficiency of the membrane by minimizing the increase and the decrease in the effective surface area of the membrane per unit volume.

Recently, as a new process for treating wastewater, membrane bio-reactor (MBR) systems that combine and treat membranes with existing methods of biological treatment are known to show excellent performance.

The membrane bioreactor (MBR) system refers to a process in which wastewater treatment can be continuously performed by immersing the separator in an aeration bath in a conventional biological treatment process. In other words, this system is used in place of the existing settling bath. However, when the MBR system currently developed is applied to an actual wastewater treatment process, the biggest problem is that contaminants contained in the wastewater contaminate the membrane surface. Therefore, physical and chemical methods such as air cleaning, intermittent inhalation, chemical cleaning, and backwashing have been used to minimize such membrane contamination. However, these methods are used only for membranes having physical and chemical properties of the membrane itself. This is possible.

Currently, hollow fiber membranes are mostly used in MBR systems in consideration of productivity and system capacity. The hollow fiber membrane has a diameter of about 0.2 to 2 mm and a hollow hollow tube, and has a high productivity because the effective surface area ratio of the membrane per unit volume is very high compared to membrane modules having different shapes of the same volume. Because of its ease, it is widely used in various fields. However, in the case of hollow fiber membranes, unlike flat membranes, mechanical strength tends to be determined and maintained by the material and structure of the membrane. Therefore, most of the hollow fiber membranes applied to the MBR system at home and abroad were made of a polyolefin-based polymer material having excellent mechanical strength.

However, polyolefin-based polymers are hydrophobic polymers, which have low water permeability because they do not easily control the size of pores or impart hydrophilicity, and have a problem that the hollow fiber membranes are broken or cut off due to excessive aeration. have. Accordingly, in the case of Xenon, Canada, polyvinylidene difluoride (PVDF) is coated on a polypropylene (PP) woven hollow fiber support to develop a hollow fiber membrane having excellent mechanical strength. Due to the large diameter, the effective area ratio of the membrane per unit volume is low and the manufacturing process is very complicated (US Pat. No. 6,354,444, US Pat. No. 5,914,039, and US Pat. No. 5,472,607). Therefore, there is an urgent need to develop a high strength hollow fiber membrane for water treatment having excellent transmittance while maintaining excellent mechanical strength capable of withstanding external physical shocks such as air cleaning.

Accordingly, the present inventors made an effort to develop a hollow fiber membrane for wastewater treatment to which the MBR system is applied due to its excellent mechanical strength and permeability. As a result, reinforcing fibers made of long fibers of polymer filaments in the center of the hollow fiber membrane yarn) A hollow fiber membrane having a multi-lumen structure in which a bundle is embedded and a plurality of lumens is surrounded around the bundle of reinforcing fibers, and the breakage or cutting of the hollow fiber membrane due to external physical impact The present invention has been completed by recognizing that it is possible to minimize the increase of the diameter of the hollow fiber membrane and the decrease of the effective surface area of the membrane per unit volume due to the intrinsic of the reinforcing fibers.

Accordingly, the present invention is a multi-tubular hollow fiber membrane formed with a structure of a bundle of reinforcing fibers and a plurality of tubes in the center, and the MBR system is applied because the mechanical properties are improved and the effective surface area of the membrane per unit volume is large, so that the permeability is excellent. The purpose is to provide a multi-tubular hollow fiber membrane useful for wastewater treatment.

The present invention is embedded in the inner center of the hollow fiber reinforcement fiber bundle (bundle) consisting of long fibers of several strands of polymer filament, surrounded by a plurality of independent tubes having a diameter of 100 ~ 1000 ㎛ around the bundle Since a multi-lumen structure is formed, the high strength multi-tubular hollow fiber membrane for wastewater treatment applied to a membrane bioreactor (MBR) system is characterized.

In addition, the present invention is to prepare a spinning solution by dissolving the polymer compound in an organic solvent, and the step of leaving for 20 to 26 hours at room temperature to remove bubbles;

Adding a reinforcing fiber to the spinning solution from which the bubbles are removed to produce a hollow fiber membrane through a wet and dry spinning method; And

Storing the prepared hollow fiber membrane in pure water for 20 to 26 hours, followed by hydrothermal treatment for 4 to 8 hours in hot water at 50 to 70 ° C. to produce a multi-tubular hollow fiber membrane having a reinforcing fiber in the center thereof;

There is another feature in the method for producing a high strength multi-tubular hollow fiber membrane for wastewater treatment, including.

The present invention will be described in more detail as follows.

The present invention has a reinforce filament-yarn bundle made of long filament of polymer filament in the inner center of the hollow fiber, the multi-lumen surrounding a plurality of lumens around the bundle of reinforcing fibers It relates to a hollow fiber membrane for wastewater treatment having a structure formed.
Conventional hollow fiber membranes comprising only single-lumen or multi-lumen structures have a problem in that breakage and cutting of membranes are caused by external physical shocks, and reinforcing short fibers are randomly distributed. The conventional hollow fiber membrane of the conventional form has a problem of poor permeation efficiency. On the contrary, in the present invention, the reinforcing fiber bundle is embedded in the inner center of the hollow fiber, and by forming a multi-pipe structure in which a plurality of pipes surround the reinforcing fiber bundle, the problem of the conventional hollow fiber membrane can be obtained at once. there was. That is, in the present invention, by embedding the reinforcing fiber bundles only in the inner center of the hollow fiber, the reinforcing fibers randomly embed the reinforcing fibers inside the hollow fiber in the conventional invention, thereby preventing the reinforcing fibers from interfering with the flow of the permeate transmitted through the inner tube, thereby decreasing the permeability of the membrane. In order to improve the problem, and to form a multi-tubular structure surrounded by a plurality of tubes having a specific diameter size around the bundle of reinforcing fibers, the membrane permeability can be increased due to the reinforcing fiber insertion or the effective area per unit volume can be minimized to reduce the permeability of the membrane. Gain the effect of maximizing. Therefore, the hollow fiber membrane of the present invention is characterized in that it is a high strength multi-tubular hollow fiber membrane having excellent membrane permeation efficiency and mechanical properties at the same time.

Referring to the structure of the high-strength tubular hollow fiber membrane according to the present invention in detail.

The hollow fiber membrane according to the present invention, as shown in Figure 1, the technical configuration of the hollow fiber membrane formed of a structure in which a bundle of reinforcing fibers in the inner center of the hollow fiber, a plurality of tubes surrounding the surroundings in one strand of the hollow fiber membrane There are features of the award.

The reinforcing fiber is a long fiber composed of several thin polymer filaments, for example, one or two or more selected from polypropylene, polyethylene, and polystyrene may be used. The reinforcing fiber is preferably 100 to 500 μm, and if it is out of the above range, there is a problem that the mechanical strength of the hollow fiber membrane is weak or the diameter of the membrane is large.

In addition, the tube surrounding the reinforcing fiber is used for the purpose of improving the permeability by minimizing the increase in the diameter due to the intrinsic of the reinforcing fiber and the reduction of the effective surface area of the membrane per unit volume, thereby having a diameter of 100 to 1000 ㎛. Do. If the diameter of the tube is less than 100 µm, the inner diameter of the tube is too small to allow the permeation material to move. If the diameter is greater than 1000 µm, the inner diameter becomes too large to reduce the effective area of the unit volume membrane. It is preferable to use 4 to 5 of these tubes, and if the number of tubes is less than 4, the effective area of the membrane is reduced. If the number is more than 5, the mechanical strength of the hollow fiber membrane is weakened or the diameter of the hollow fiber membrane is decreased. There is a problem that it becomes too large to decrease the effective area of the membrane per unit volume.

As the material of the high strength multi-tubular hollow fiber membrane according to the present invention, any polymer compound that can be prepared by a conventional phase transition method may be used, and for example, one selected from polysulfone-based, polyimide-based, and polyfluoro-based polymers may be used. More preferably, polyisulfone, polysulfone, polyvinylidenedifluorolide, polyisimide, and polyacrylonitrile are preferably used.

On the other hand, the manufacturing method of the high strength multi-tubular hollow fiber membrane for water treatment of this invention is as follows.

First, 5 to 40% by weight of the polymer compound is dissolved in 60 to 95% by weight of an organic solvent to prepare a polymer spinning solution, and then left to stand at room temperature for 20 to 26 hours.

If the amount of the organic solvent in the spinning solution is out of the above range there is a problem that the hollow fiber membrane itself is not formed. In addition, the organic solvent may be selected from dimethylacetamide, chloroform, tetrahydrofuran, N, N'-dimethylformamide and 1-methyl-2-pyrrolidinone. In the preparation of the polymer spinning solution, it is possible to use an additive which imparts various functionalities according to the purpose of the hollow fiber membrane. In order to remove bubbles of the prepared spinning solution, the mixture is left at room temperature for 20 to 26 hours.

Next, reinforcing fibers are added to the spinning solution from which the bubbles are removed to prepare a hollow fiber membrane through a wet and dry spinning method.

The wet-and-dry spinning process is used in manufacturing a general hollow fiber membrane, and a nozzle having a finger-like structure or a sponge-like structure may be used. The dry and wet spinning is not particularly limited to spinnerets (nozzles) designed to enable the production of the hollow fiber membranes presented in the present invention, but the specific spinneret structure of the present invention has a discharge port of reinforcing fibers in the center and around the spinneret. There are a plurality of internal coagulant discharge ports, and the polymer solution is discharged between the discharge port of the reinforcing fiber and the discharge port of the coagulating liquid. The reinforcing agent, the polymer solution and the internal coagulant are discharged through a spinneret at the same time. The reinforcing fiber is embedded in the center of the hollow fiber to form a plurality of tubes independently. It is important to have a plurality of tubes embedded in the center of the cross section of the hollow fiber membrane and at regular intervals and thicknesses.
In the manufacturing process to produce a hollow fiber membrane embedded in the reinforcing fiber in the center. The coagulant for forming the hollow of the hollow fiber membrane is pure water, dimethylacetamide, chloroform, tetrahydrofuran, N, N'- dimethylformamide and 1-methyl-2-pyrrolidinone, polyethylene glycol, propylene glycol, ethylene Glycols and the like can be used.

Next, the hollow fiber membrane prepared above is stored in pure water for 20 to 26 hours, followed by hydrothermal treatment for 4 to 8 hours in hot water at 50 to 70 ° C. to prepare a multi-tubular hollow fiber membrane having reinforcing fibers in the center. .

By extracting the organic solvent remaining inside the hollow fiber membrane through the hydrothermal treatment, it is possible to manufacture a multi-tubular hollow fiber membrane having a reinforcing fiber embedded in the center and surrounding a plurality of tubes.

The multi-tubular hollow fiber membrane manufactured according to the present invention has a structure in which a reinforcing fiber is embedded in the center and a tube is surrounded around the hollow fiber membrane of one strand to minimize the effective surface area per unit volume while maintaining high mechanical strength. The membrane's permeation efficiency can be maximized.

Hereinafter, the present invention will be described in detail with reference to the following Examples, but the present invention is not limited by the Examples.

Example 1

15% by weight of polyvinylidene fluoride (PVDF) was dissolved in 85% by weight of dimethylacetamide (DMAc) to prepare a spinning solution, and then left at room temperature for 24 hours to remove bubbles in the solution.

Using the spinning solution and the reinforcing fiber prepared above, a hollow fiber membrane was prepared through a general wet and dry spinning process.

The hollow fiber membrane obtained above was stored in pure water at room temperature for 24 hours, and then subjected to hydrothermal treatment for 6 hours using hot water at 60 ° C. to extract the organic solvent remaining in the hollow fiber membrane. A high-strength, multi-tubular hollow fiber membrane for water treatment, including a plurality of lumens, was prepared around reinforce filament-yarn.

The thickness, mechanical strength and permeability of the hollow fiber membranes prepared above were measured, and the results are shown in Table 1 below.

Example 2

In the same manner as in Example 1, 15% by weight of polysulfone (PSf) was carried out using 85% by weight of dimethylacetamide (DMAc) to perform high-strength multi-tubular water treatment including reinforcement filament- yarn. A hollow fiber membrane was prepared.

The thickness, mechanical strength and permeability of the hollow fiber membranes prepared above were measured, and the results are shown in Table 1 below.

Comparative Example 1: Single-Lumen Hollow Fiber Membrane

The hollow fiber membrane having a single-lumen was prepared using the same tube-in-orifice type nozzle as in Example 1, but using a conventional tube-in-orifice type nozzle.

The thickness, mechanical strength and permeability of the hollow fiber membranes prepared above were measured, and the results are shown in Table 1 below.

Comparative Example 2: Multi-lumen Hollow Fiber Membrane

The hollow fiber membrane was purchased from INge AG, and the thickness, mechanical strength and permeation characteristics of the membrane were measured, and the results are shown in Table 1 below.

[Measurement Method]

(1) Film thickness: It measured using the SEM photograph.

(2) Mechanical strength: Tensile strength was measured according to the ASTM method.

(3) Permeation characteristics: The hollow fiber membrane was prepared by immersing the module having a certain length and the number of strands in a water tank, and then suctioning the inside of the hollow fiber membrane outside by connecting a low vacuum pump to both ends of the module.

division Film thickness (㎛) Pure Permeability (LMH) Mechanical strength (kg / fiber) Example One 100 12 250 2 100 13 230 Comparative example One 150 15 63 2 150 10 98

As shown in Table 1, Examples 1 to 2 manufactured a hollow fiber membrane having a multi-pipe structure in which reinforcement filament-yarn is embedded in the center and includes a plurality of tubes (lumen) around the center according to the present invention. Compared to Comparative Example 1, which is a hollow fiber membrane having a single-lumen, and Comparative Example 2, which is a conventional multi-lumen type hollow fiber membrane, the thickness of the membrane is excellent, the mechanical strength is excellent, and Minimizing the effective surface area resulted in an improved permeability of the membrane.

As described in detail above, a high-strength, multi-tubular hollow fiber membrane comprising a plurality of lumens centered on reinforce filament-yarn embedded in the inner center of the membrane is a membrane per unit volume while maintaining high mechanical strength. In addition to minimizing the reduction of the effective surface area, it is possible to maximize the permeation efficiency of the membrane, as well as for wastewater treatment, which is applied to all polymers manufactured by using the conventional phase transition method, and especially hollow fiber membranes having various functionalities. It is applicable to the manufacture of membranes.

Claims (7)

In the inner center of the hollow yarn there is embedded a bundle of reinforcing fibers made of long fibers of a plurality of strands of polymer filament, To form a multi-lumen structure surrounded by a plurality of independent tubes having a diameter of 100 ~ 1000 ㎛ around the bundle of reinforcing fibers High strength multi-tubular hollow fiber membrane for wastewater treatment, which is applied to a membrane bioreactor (MBR) system. The high-strength tubular hollow fiber membrane for water treatment according to claim 1, wherein the polymer filament has a diameter of 100 to 500 µm. The high strength multi-tubular hollow fiber membrane for water treatment according to claim 1, wherein the reinforcing fiber is one or two or more selected from polypropylene, polyethylene, and polystyrene. delete The high strength multi-tubular hollow fiber membrane for water treatment according to claim 1, wherein 4 to 5 pipes are used. delete delete

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