JPH0994442A - Separation membrane module and its operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separation membrane module capable of obtaining the permeated water having a minute content of viable bacteria at a stable flow rate even when a raw water is substantially free from a disinfectant. SOLUTION: An envelope-shaped membrane 2 contg. a permeated water passage material 3 is wound on a permeated water collecting pipe 1, a raw water passage material 4 is interposed between the wound layers to constitute a membrane element A, and the element A is placed in an outer cylinder 5 to form a spiral separation membrane module. One or both sides of the raw water passage material 4 or permeated water passage material 3 are coated with an antibacterial substance. The module is operated by a batch process to return the nonpermeated raw water to a raw water tank.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separation membrane module capable of preventing the growth of live bacteria during operation and ensuring the quality of permeate and a stable permeation flow rate, and a method of operating the same.

[0002]

2. Description of the Related Art Conventionally, household water purifiers are often used in which tap water is treated with activated carbon and then subjected to membrane separation. For example, sodium hypochlorite contained in raw water is used. It has the advantage that it can be removed by activated carbon treatment and that deterioration of the film due to sodium hypochlorite can be prevented. However, between the activated carbon layer and the separation membrane, live bacteria proliferate due to lack of the disinfectant, leading to deterioration of the permeated water, and it is also unavoidable that the permeation flow rate decreases.

[0003]

Therefore, it has been proposed to perform ultraviolet sterilization treatment, hot water sterilization treatment, chlorine sterilization treatment, or the like on the downstream side of the separation membrane. In these treatments, viable bacteria on the outer surface of the membrane are used. The reduction of the permeation velocity due to the breeding cannot be eliminated, and the water purification system is complicated, the maintenance is difficult, and the energy consumption is increased. An object of the present invention is to provide a separation membrane module and a method for operating the same, which can obtain permeated water having a small amount of viable bacteria at a stable flow rate even when treating raw water substantially containing no disinfectant. Especially.

[0004]

In the separation membrane module according to the present invention, an envelope-shaped membrane having a permeate passage material inside is wound around a permeate collecting pipe, and a raw water passage material is provided between the winding layers. In a spiral type separation membrane module in which an interposed membrane element is housed in an outer cylinder, one or both of a raw water passage material and a permeated water passage material is coated with an antibacterial substance. , The non-permeated raw water is returned to the raw water tank by the batch method.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. 1A shows a spiral membrane element used in the present invention, and FIG. 1B shows a separation membrane module according to the present invention.
In (a) of FIG. 1 and (b) of FIG. 1, 1 is a permeated water collecting pipe, and a perforated plastic pipe can be used. 2 is an envelope-shaped membrane, and two separation membranes (reverse osmosis membrane,
The permeated water passage material 3 is disposed between the ultrafiltration membrane and the microfiltration membrane, etc., three sides of these membranes are sealed by fusion or an adhesive, and the remaining open ends are placed in the permeated water collection tube 1. The permeated water flow path between the membranes is connected to the inside of the permeated water collection tube 1 through the hole of the tube wall. Reference numeral 4 denotes a raw water passage material, which is wound around the permeated water collecting pipe 1 together with the envelope-shaped membrane 2. Reference numeral 5 denotes an outer cylinder, on which the spiral membrane element A is concentrically inserted via spacers 51, 51. 52 is a raw water inlet, 53
Is a non-permeate (concentrated raw water) outlet. The raw water passage material 4 is coated with a water-insoluble antibacterial substance such as silver or copper. This coating is as thin as possible, for example a vapor deposited coating is preferred. The permeate passage material 3 can also be coated with an antibacterial substance.

In the above spiral type separation membrane module, raw water is made to flow through the raw water passage material in the axial direction of the module, and the solvent in the raw water passes through the membrane to prevent solute from passing through to form an envelope membrane. Permeate is generated, this permeate reaches the inside of the permeate collection pipe through the permeate passage material, and flows out from one end of the permeate collection pipe. In the raw water passage material 4 and the permeated water passage material 3, the flow velocity is slowed down to create an efficient flow with less fluid resistance, and conversely, the flow velocity is increased to contaminate dirt components in the raw water on the separation membrane surface. A material that is compatible with the two requirements contradictory to the prevention of the accumulation of dust is used, and a plastic net, a non-woven fabric, a woven fabric, or the like can also be used.

In order to treat tap water using the spiral type separation membrane module according to the operation method of the separation membrane module according to the present invention, a batch method is used as shown in FIG. In this case, depending on the amount of permeated water taken out, the raw water tank 61 may be supplemented with dechlorinated water treated with activated carbon (64
Is a raw water supply pipe), the raw water sent from the raw water tank 61 to the separation membrane module F by the pump 62 contacts the antibacterial raw water passage material, and is further returned to the raw water tank 61 by the return pipe 63 for circulation. Therefore, there is almost no chance of breeding live bacteria, and the growth of live bacteria can be well prevented even in the absence of soda hypochlorite.

[0008] Therefore, it is possible to obtain good quality drinking water containing a small amount of viable bacteria. Also, the adherence of live bacteria to the membrane surface
Since the membrane can be prevented from being clogged, the amount of permeated water can be stably maintained. This effect can be confirmed by comparing the operation results of the example and the comparative example described below. In addition, the separation membrane module and the method for operating the same according to the present invention are particularly preferably used for treating the above-mentioned tap water, but it is a solid suspension suspended in raw water of low water quality or dissolved. It can also be used to remove existing organic substances or ions.

[0009]

Examples [Example 1] Spiral separation membrane module (ES10-D1CX, membrane area 0.45 m ² ) manufactured by Nitto Denko KK
In the above, silver was vapor-deposited on the raw water passage material. [Example 2] Spiral type separation membrane module manufactured by Nitto Denko Corporation (ES10-D1CX, membrane area 0.45 m ² ).
In the above, silver was vapor-deposited on the raw water passage material and the permeated water passage material. [Example 3] Spiral separation membrane module manufactured by Nitto Denko Corporation (ES10-D1CX, membrane area 0.45 m ² ).
In the above, silver was vapor-deposited on the permeated water passage material. Comparative Example A spiral type separation membrane module (ES10-D1CX, membrane area 0.45 m ² ) manufactured by Nitto Denko Corporation was used as a comparative example.

A total of four spiral type separation membrane modules of these Examples and Comparative Examples are connected in parallel as shown in FIG. 3, and a circulation pump is provided between the raw water tank 61 and this group of parallel modules. 62 was inserted, and the permeated water and non-permeated water (concentrated raw water) of each module were piped so as to be returned to the raw water tank 61. (64 is a raw water supply pipe, 65 is an overflow flow pipe) And raw water dechlorinated by activated carbon treatment (effective chlorine concentration 0.01 ppm or less, electric conductivity 146 ± 2 μs /
cm, water temperature 27-28 ° C., viable cell count 3.4 × 10 ³ cells / c
c) is supplied to the raw water tank 61 and the discharge pressure of the pump 62 is 1 ± 0.1 kg / cm ² raw water passage material, recovery rate [(permeated water amount / supplied water amount) × 100%] 25 to 35%, initial permeated water amount 50 〜60 cc / min, after 250 hours of continuous operation, the performance retention rate of permeated water amount for each separation membrane module,
Performance retention rate of conductivity inhibition rate [(value after 250 hours of continuous operation / value immediately after start of operation) × 100%] and viable cell count in permeate (cells / cc. 30 ° C., culture colony value for 7 days) )
Was measured and found to be as shown in Table 1.

[0011]

[Table 1]

As is clear from the results of the performance retention rate of the amount of permeated water in these measurement results, in Comparative Example 1, the permeated water amount is largely decreased with time, whereas in Example, the permeated water amount is substantially decreased with time. It is clear that there is no degradation and no membrane fouling. Further, from the measurement result of the viable cell count in the permeate, since the viable cell count of the example is sufficiently smaller than the viable cell count of the comparative example, in the examples, in addition to the passage inhibition of the viable cell by the membrane, It is clear that the suppression of the growth of live bacteria by the antibacterial substance effectively contributes to the reduction of live bacteria in the permeate.

[0013]

EFFECTS OF THE INVENTION According to the present invention, it is possible to suppress the growth of bacterial cells on the membrane surface of the separation membrane module, to prevent clogging of the membrane surface with the bacterial cells, and to guarantee a stable permeation flow rate. , The permeated water quality can be improved by drastically reducing the number of viable bacteria in the permeated water. Moreover,
The material for the permeated water passage and the material for the raw water passage are simply coated with an antibacterial substance, and the advantages of the separation membrane module such as simplicity of the entire water purification system, ease of management and maintenance, and low operating energy can be maintained.

[Brief description of drawings]

1 (a) is an explanatory view showing a spiral membrane element used in the present invention, and FIG. 1 (b) is an explanatory view showing a membrane separation module according to the present invention.

FIG. 2 is an explanatory view showing an operation method of the membrane separation module according to the present invention.

FIG. 3 is an explanatory diagram showing a test circuit for performance comparison between an example and a comparative example of the membrane separation module according to the present invention.

[Explanation of symbols]

 1 Permeate Collection Tube 2 Envelope Membrane 3 Material for Permeate Passage 4 Material for Raw Water Passage 5 Outer Cylinder 61 Raw Water Tank 62 Pump F Membrane Separation Module 63 Return Pipe 64 Raw Water Supply Pipe

Claims (2)

[Claims] 1. An envelope-shaped membrane having a permeated water passage material inside is wound around a permeated water collecting pipe, and a membrane element having a raw water passage material interposed between the wound layers is housed in an outer cylinder. In the spiral separation membrane module, one or both of the raw water passage material and the permeate passage material are coated with an antibacterial substance. 2. A method for operating a separation membrane module, which comprises operating the separation membrane module according to claim 1 by a batch method in which unpermeated raw water is returned to a raw water tank.