JPH07116423A - Membrane type sedimentation and separation tank - Google Patents

Abstract

PURPOSE:To efficiently and continuously subject a raw soln. containing a turbid component in high concn. to solid-liquid separation by a backwashable external pressure type membrane filter by arranging an air jet means in a sedimentation and separation tank wherein the external pressure type membrane filter and inclined plates are arranged at the position under the membrane filter and above the inclined plates. CONSTITUTION:An air jet means 3 is arranged below a membrane filter 2 and above inclined plates 4 so that air bubbles generated from the air jet means 3 to rise strike against the separation membrane of the membrane filter 2 efficiently. The jet orifices of the air jet means 3 are arranged in a direction not opposed to the membrane filter 2, that is, in a downward direction so as not to clog the jet orifices with sludge or turbidity matter at the time of the stop of air injection. The inclined plates 4 develop function exerting no effect of stirring on the sludge or turbidity matter separated from the surfaces of the separation membranes of the membrane filter to once reach the inclined plates and rapidly staving off the same.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane-type sedimentation separation tank for solid-liquid separation of a stock solution (solution to be treated) containing a high-concentration solid content, and more specifically, a stock solution containing a high-concentration solid content continuously. The present invention relates to a membrane type precipitation separation tank capable of efficiently taking out a solid content in a high-concentration state to the outside of the system while filtering the same.

[0002]

2. Description of the Related Art In recent years, water sources for water supply have been contaminated due to environmental pollution, and various additional treatments are required for the water purification technology in the conventional water purification process of coagulated sand filtration. On the other hand, the examination of replacing the river water clarification process by sand filtration, which is the main technology of water purification and occupies most of the water purification plant, with a membrane filter is proceeding rapidly (Ministry of Health and Welfare MAC-21 project ).

On the other hand, in the general industry of semiconductors and the like, the sophistication of the technology has advanced the sophistication of the cooling liquid used in the polishing / cutting process, and its recovery and reuse has become a problem.
Centrifugation, application of conventional filtration technology, etc. have been studied for solid-liquid separation of a stock solution containing high-concentration turbidity components in the general industry, which is represented by this cooling liquid recovery. Solid-liquid separation with a filter is being judged to be advantageous in terms of continuity, handling, accuracy, and the like.

Membrane filters include an external pressure type that allows liquid to permeate from the outside of the membrane and an internal pressure type that allows liquid to permeate from the inside to the outside of the membrane. When processing, an external pressure type is often used.
In addition, the membrane filter backwashes turbidity accumulated on the membrane surface,
That is, in the case of the external pressure type, turbidity is removed from the membrane surface by applying internal pressure from the inside of the membrane to separate it, or by applying some force to the membrane to disturb the solid-liquid interface on the outside of the membrane to separate the turbidity. It can be separated.

However, on the premise of continuous treatment, if the suspended components separated from the membrane surface are accumulated again on the membrane outer surface in the filtration step, the treatment efficiency will be extremely lowered.

[0006] As a method for improving the sedimentation property of the sedimentation solid content, a slant plate has been used in the water purification technology in particular, and it has already been combined with an external pressure type membrane filter.
No. 154354. However, JP-A-5-
In the method of No. 154354, the whole undiluted solution side including the part of the inclined plate may be agitated, which not only prevents sedimentation of the suspended component on the inclined plate, but also the suspended component which has settled to this part is re-membrane. There was a risk of backflow to the filter section. Further, in this method, when the membrane filter is arranged on the upper part of the inclined plate, the effect of disturbing the solid-liquid interface on the outer surface of the membrane is small, and the turbid component is not sufficiently separated from the outer surface of the membrane. It was

[0007]

SUMMARY OF THE INVENTION In view of these conventional techniques, the inventors of the present invention have installed a gas injection means at an intermediate position between the external pressure type membrane filter and the inclined plate, and the outside of the membrane by the upward bubbles. By violently disturbing the solid-liquid interface of, the turbidity accumulated on the outer surface of the membrane is efficiently released, while the inclined plate located below the turbidity is not affected by the liquid stirring and the separated sedimentable turbidity component is removed. The present inventors have found that the settling by the inclined plate can be quickly achieved and the present invention has been achieved.

An object of the present invention is to provide an external pressure type membrane filter capable of backwashing, and a membrane type sedimentation separation tank for efficiently and continuously separating a stock solution containing a high-concentration suspended matter component into a solid-liquid separation. It is in.

[0009]

That is, according to the present invention, in a settling separation tank in which an external pressure type membrane filter and a slant plate are disposed, a jetting means is provided below the membrane filter and above the slant plate. Is a membrane-type sedimentation separation tank.

[0010]

The present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a membrane type precipitation separation tank of the present invention. The membrane-type sedimentation separation tank of the present invention comprises a tank 1, in which a membrane filter 2, a gas jet means 3 and an inclined plate 4 are arranged.

The membrane filter 1 referred to in the present invention may be either a homogeneous membrane or an asymmetric membrane as a separation membrane, or a porous membrane as long as it can be backwashed. A non-porous film may be used. The membrane may be in any form such as a hollow fiber membrane, a tubular membrane or a flat membrane. If filtration using a membrane filter (solid-liquid separation) is external pressure filtration, not only the so-called external pressure method that pressurizes the raw liquid (treatment liquid) side but also the treatment liquid side, that is, the secondary side is suctioned. It may be suction filtration. In particular, suction filtration is preferable in consideration of backwashing efficiency.

The backwash as referred to in the present invention is not only the so-called backwash in which the secondary side is pressurized to reversely flow the treatment liquid to perform washing, but also the hammer phenomenon accompanying the stop of suction filtration. Any method such as shaking the membrane to shake off turbidity, backwashing air by sending air from the secondary side, simply stopping filtration by external pressure, while disturbing the solid-liquid interface on the outer surface of the membrane by air bubbles and stirring May be

The blower means 2 is a device capable of generating bubbles having a diameter of about 1 to 20 mm, and a blower tube is usually used. The blowing means is preferably one that generates a gas of the order of several N liter / m ² / min as bubbles with respect to the membrane area of the membrane filter.

The squirting means is arranged below the membrane filter and above the inclined plate, at an intermediate position between them. The distance between the squirting means and the membrane filter is not particularly limited, as long as the bubbles generated from the squirting means and rising up efficiently hit the separation membrane in the membrane filter. Further, if the air bubbles from the squirting means do not agitate sludge or suspended matter that has settled and deposited between the inclined plates, the squirting means may be arranged in a state of being close to the inclined plates.

When a fumarole tube having a large number of fumaroles is used as the fumarolic means, the fumaroles are preferably arranged so as not to face the membrane filter, that is, downward. This is because if the fumaroles face downward, there is no possibility that the fumaroles will be clogged with sludge or suspended matter when the fumarole is stopped. Further, it is preferable that the fumaroles are evenly distributed throughout the fumarolic pipe so that the bubbles uniformly hit the entire separation membrane.

In order to enhance the action of applying air bubbles to the membrane filter to oscillate the separation membrane, the separation membrane in the membrane filter is arranged at an angle to the rising air bubbles. It is preferable.

As the slant plate 4, sludge and suspended matter separated from the surface of the separation membrane of the membrane filter, which have reached the slant plate once, are quickly moved away from the separation membrane without the influence of liquid stirring. The number and spacing of the plates are not particularly limited as long as the functions can be exhibited. As a material for forming the inclined plate, a material in which turbid components are easily slid off is preferable, and examples thereof include plastics such as vinyl chloride and materials having a smooth surface made of a corrosion resistant metal such as stainless steel. The angle of the inclined plate is preferably 50 ° to 70 °, which is an angle at which an ascending liquid flow is unlikely to occur and a suspended component is likely to slide off.

The positional relationship among the membrane filter, the gas jetting means, and the inclined plate is not particularly limited as long as they are arranged in this order from above as described above, but they should be parallel to the width direction. It is preferably arranged. In addition, a plurality of sets of these may be used in the precipitation separation tank depending on the amount of stock solution to be treated.

The undiluted solution (the solution to be treated) may be introduced into the sedimentation separation tank from any position. However, considering the sedimentation of suspended components, it is preferably at least above the position of the gas jetting means and above the position of the membrane filter. More preferably, it is above.

The bottom of the sedimentation tank is preferably shaped like a funnel so that the accumulated sludge and suspended matter can be collected and taken out of the tank efficiently.

[0021]

【Example】

Example 1 Polyethylene hollow fiber membrane (outer diameter 410 μm, inner diameter 270 μm
m, fractionation performance 0.1 μm, manufactured by Mitsubishi Rayon Co., Ltd.) to prepare a Russell knitted fabric having a width of 400 mm and a length of 300
Cut out into several mm, stack several sheets, fix one end with urethane resin, cut off the tip of the part fixed with resin with the knitted fabric tip part to make the filter module end face, and leave the other end of the Russell knitted fabric as it is. A membrane module having a membrane area of 4 m ² was formed. A suction filtration jig was attached to the end face of this module to produce a suction type hollow fiber membrane filter.

At a position near the bottom of the aquarium, a height of 400 m
m, a tilt angle of 60 °, and a tilt plate spacing of 4 cm / sheet was set. Two fumaroles with a diameter of 1 mm are provided above this inclined plate.
A vinyl chloride fumarole having a diameter of 10 mm and having a diameter of 10 cm / cm was set so that the fumarole faced downward. The distance between the fumarole and the inclined plate was 20 mm. Further, the jig for suction filtration of the hollow fiber membrane filter is on the upper side, the other end of the hollow fiber membrane knitted fabric is on the lower side, and is 20 mm directly above the fumarole, and the hollow fiber membrane has an inclination of about 85 degrees with respect to the horizontal direction. I set it like this. The jig for suction filtration, the fumarolic pipe, and the inclined plate are arranged so as to be substantially parallel to each other. The bottom of the sedimentation tank is funnel-shaped.

A test liquid prepared by dispersing 1000 mg / liter of red iron oxide in pure water was introduced into the sedimentation separation tank from the upper portion of the tank, and 320 liters / piece / H, 0.08 m / H was used for 1 hour.
Filtration was carried out continuously with a cycle of suction filtration for 0 minutes and then stop for 2 minutes. When stopped for 2 minutes, bubbling was carried out from the fumarole at 16 Nl / min to shake off red iron oxide particles accumulated on the surface of the hollow fiber membrane. The transition of the initial transmembrane pressure difference of the membrane filter (transmembrane pressure difference immediately after the start of suction filtration) in this test is shown in FIG.

Comparative Example 1 A filtration test was carried out in exactly the same manner as in Example 1 except that a precipitation separation tank in which a fumarolic tube was installed below an inclined plate was used, and the transition of the initial transmembrane pressure difference is shown in FIG. Indicated.

Comparative Example 2 A filtration test was carried out using the same precipitation separation tank as used in Example 1 except that the fumarole was not installed. Instead of bubbling, filtered water was allowed to flow backward from the secondary side at 1 kg / cm ² for 1 minute when the filtration was stopped. The transition of the initial transmembrane pressure difference in this case is also shown in FIG.

[0026]

When the precipitation separation tank of the present invention is used,
Since the suspended matter accumulated on the outer surface of the membrane is quickly removed from the vicinity of the membrane filter, it stabilizes when the initial transmembrane pressure difference is early low, whereas it stabilizes when the precipitation separation tank of the comparative example is used. It took time, and the initial transmembrane pressure difference was high.

[Brief description of drawings]

FIG. 1 is a schematic view showing a membrane type precipitation separation tank of the present invention.

FIG. 2 is a graph showing the transition of the initial differential pressure of the membrane filter in the filtration test.

[Explanation of symbols]

 1 Tank 2 Membrane Filter 3 Fume Means 4 Tilt Plate

Claims (1)

[Claims] 1. A settling / separation tank in which an external pressure type membrane filter and an inclined plate are arranged, and a gas ejecting means is arranged below the membrane filter and above the inclined plate. Membrane type precipitation separation tank.