JPH01191038A - Water quality evaluating method - Google Patents

Abstract

PURPOSE:To easily set the area of a film in consideration of a decrease of flux by evaluating the quantity of water from a display of clogging degree=100X(1-B/A), where A is initial flux and B is flux which is a specific time later. CONSTITUTION:Compressed air supplied from an air compression source 1 is supplied to a pressure container 6 through a pressure-proof hose 2. A module 9 which is made of a hollow thread film and has small film area is dipped in the water in a water collection bottle 8 and specific air pressure is applied to the bottle 8 to filter the water through the module 9. The liquid 7 in the bottle 8 is filtered from the external surface of the hollow thread film of the module 9 with the air pressure and discharged to a liquid discharge speaker 11 through a flowmeter 10. At this time, the quantity of the water is evaluated from a display of clogging degree=100X(1-B/A), where A is the initial flux and B is the flux which is the specific time laser. Consequently, the film area is easily set in consideration of the decrease of the flux.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for evaluating the water quality of a moderate amount of liquid, such as drinking water, when the liquid is filtered through a membrane.

[Conventional technology]

In recent years, technology for filtering and separating various liquids using various porous membranes including hollow fiber membranes has rapidly advanced, and for example, water purifiers for drinking water using hollow fiber membranes have also been provided.

Normally, the lifespan of the membrane (clogging) when filtration is performed using a membrane.
It depends on the content of insoluble substances of various sizes that cannot pass through the membrane surface. In addition, various membranes are also used to filter process water used in the pharmaceutical industry, food industry, and the like.

However, in most cases, the total surface area of the membrane used in these applications is determined by setting its replacement life, but it also depends on how much of the liquid to be filtered contains the substance to be filtered relative to the membrane. In many cases, it is difficult to determine whether or not the total membrane area is suitable, and in most cases it is determined empirically by appropriately setting the total membrane area and filtering the collected liquid. In particular, it has been difficult to judge the amount of clogging substances in the water when it is filtered with a membrane, such as well water existing in the natural world or tap water originating from lakes, marshes, and rivers.

[Means for solving problems]

In view of the current situation, the present inventors have established a water quality evaluation method necessary for predicting and setting the required total area of hollow fiber membranes in advance, and further setting the replacement life of membrane modules in advance. It's arrived.

The gist of the present invention is to immerse a module with a small membrane area made of a hollow fiber membrane in water in a water sampling bottle, apply a predetermined air pressure to the water sampling bottle, and filter water by the module. A water quality evaluation method characterized by evaluating water quality by displaying clogging degree = 100 x [1--), where A is 7 lacs (ml 7 minutes) and B is 7 lacs (ml 7 minutes) after a predetermined time. It is in.

Hereinafter, the method of the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an embodiment of the method of the present invention, in which pressurized air supplied from an air pressurization source (1) such as a compressor passes through a pressure-resistant hose (2), and then passes through a pressure regulating valve (3). The pulp is set at a predetermined pressure based on the display on the pressure gauge (4), and is supplied to the pressure vessel (6) via the pulp (5).

On the other hand, a liquid sampling bottle (8) made of, for example, polyethylene, containing a liquid to be measured (7) is set in the pressure vessel (6). A hollow fiber membrane module (9) with a small membrane area is immersed in this liquid (7).

As the hollow fiber membrane, a known hydrophilic hollow fiber membrane or a hydrophobic hollow fiber membrane made hydrophilic can be used. Also, as a hollow fiber membrane module, the membrane area is approximately 5 to 50 cut.
``Something of the order of magnitude is used.

The hollow fiber membrane module (9) may be one in which a plurality of hollow fiber membranes are bundled into a U-shape and the ends are fixed with resin. The liquid (7) in the liquid collection bottle (8) is filtered from the outer surface of the hollow fiber membrane of the hollow fiber membrane module (9) by air pressure, passes through the flow meter (10), and is transferred to the drain beaker (11).
) is discharged.

The air pressure may be set appropriately depending on the membrane area of the hollow fiber membrane module (9), but if a pressure vessel (6) is used, it is usually 0.5 to 1.5 Yu/crrL2.
degree is most preferred.

In addition, immediately after the start of filtration, the air contained in the hollow fiber membrane module (9) and the air contained in the piping system after the hollow fiber membrane module (9) are discharged, so the amount of excess water is accurately measured. Therefore, it is preferable to measure the initial flux A usually 5 to 30 seconds after the start of filtration.

Furthermore, the measurement of flux B after a predetermined period of time may normally be carried out about 8 to 30 minutes after the start of passing.

Regarding tap water used for drinking water, if half a day or more than a day has passed since the water was sampled, there may be a change in the amount of clogging substances, mainly due to bacterial growth. After that, it is preferable to evaluate as early as possible.

〔Example〕

Next, the method of the present invention will be explained based on examples.

Example 1 The water quality of four types of tap water was evaluated using the apparatus shown in FIG. 1 under the following conditions, and the results are shown in Table 1.

(1) Hollow fiber membrane module: Mitsubishi Rayon Co., Ltd.
! &Hollow fiber EHF 270T membrane area: 10cI! L” shape = U-shape, membrane effective length 25m blade (2) Pressurized air: 1 to 9/ci” (3) Water sampling amount: 1j (4) Measurement of flux A: Measured 30 seconds after starting filtration (5 ) Measurement of 7 lux B 2 Measurements 1 minute after starting filtration Table 1 Next, the above four types of water filtration treatments were actually carried out under the following conditions, and the relationship between the cumulative filtration amount and flux was measured. The results are shown in Figure 2.

(1) Hollow fiber membrane module: Hollow fiber EHF270T manufactured by Mitsubishi Rayon Co., Ltd. Membrane area: 0.6 m'' Shape: U-shaped, effective membrane length 90 m (2) Measuring pressure 1 kiil/cm'' From Figure 2 As is clear, there is a very close relationship between the degree of clogging and the decrease in 7 lux. -〇 [Effects of the Invention] As explained above, if the degree of clogging is measured by the method of the present invention, it is possible to reduce the decrease in flux. The membrane area can be easily set taking this into account.

Furthermore, the apparatus for carrying out the method of the present invention is extremely simple and can be made compact and portable.

[Brief explanation of the drawing]

FIG. 1 shows an example of an apparatus for carrying out the method of the invention. In the figure, (1) Air pressurization source
(2) Pressure resistant hose (3) Pressure regulating valve (
4) Pressure gauge (5) Valve (6) Pressure vessel (7) Liquid (8) Liquid sampling pin (9)
Hollow fiber membrane module (10) Flow meter (11) Drain beaker is shown. Table 1 shows the degree of clogging of tap water sampled at four locations. Moreover, FIG. 2 is a graph showing the relationship between the integrated flow rate and the flux when the tap water at the four locations mentioned above is actually filtered using a hollow fiber membrane module having a constant membrane area. Ya 1 Mouth + 2 Figure f 2 3 Chin $ flow rate (m
3)

Claims (1)

[Claims] A module with a small membrane area made of a hollow fiber membrane is immersed in water in a water sampling bottle, and a predetermined air pressure is applied to the water sampling bottle.
When filtering water by this module, the initial flux (ml/min) is A, and the flux after a predetermined time (m
degree of clogging = 100 x [1-(B/min)
A) A water quality evaluation method characterized by evaluating water quality by displaying.