JPH09136020A - Crossflow membrane filtration method in drainage treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a relative velocity between water to be treated and the surface of a filtration film, to prevent the accumulation of gel on the surface of the film, and to treat drainage over a long period of time by suspending plate-shaped filtration film units, immersing them in drainage, and oscillating them. SOLUTION: In a filtration module 1, filtration film units 1a in which flat filtration films 3 are set on both sides of a support plate 2 having a channel 4 for filtrate inside are arranged in parallel and fixed in a fixed frame 5. The module 1 is suspended from a filtration film support base 9, which is the lid of an aeration tank 6, through springs 10, and an oscillator 11 is installed on the upper surface of the fixed frame 5. Drainage containing activated sludge is circulated and supplied so that the filtration films 3 in the aeration tank 6 are immersed sufficiently, and air is ejected from a diffusion pipe. At the same time, when the module 1 is strongly oscillated vertically and water to be treated is sucked by a suction pump 14, it passes through the filtration films 3 and the channel 4 in sequence and is discharged outside. In this way, the accumulation of gel on the surface of the filtration films 3 can hardly occur.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to sewage, industrial wastewater,
The present invention relates to a membrane filtration system used to purify wastewater such as domestic wastewater to the extent that it does not pollute the environment, reuse purified water as tap water, or separate solid-liquid when discharging.

[0002]

2. Description of the Related Art In the purification treatment of waste water, various chemicals and activated sludge are used to chemically and biologically purify, and finally, sludge is separated into clear water, and the clear water is used as tap water. It is generally reused or released. Then, for the separation of the sludge and the clear water, a method in which the sludge is settled in the settling tank and the clear water is used as a supernatant has been exclusively adopted. In recent years, with the development of ultrafiltration membranes and microfiltration membranes, there has been an increase in attempts to adopt solid-liquid separation by sludge settling instead of solid-liquid separation for the purpose of effectively utilizing the treatment facility site and improving processing capacity. I am doing it.

There are two methods of separation by the filtration membrane, depending on the shape of the filtration membrane to be used, (1) flat membrane method and (2) tubular membrane (hollow fiber membrane) method. From the contact direction of the filtration membrane surface (1) Total filtration method (The water to be treated flows perpendicularly to the membrane surface. Although not all the water to be treated is actually filtered through the filtration membrane, (2) There is a cross-flow filtration method (a method in which the water to be treated is flown in parallel to the membrane surface and filtration is performed on the side of the flow of the water to be treated).

[0004] From the aspect of the shape of the filtration membrane, the flat membrane method is generally used from the viewpoint of ease of handling and price, and from the aspect of the flow of water to be treated, the gel substance is less accumulated on the membrane surface. The cross flow filtration method is generally used.

In this flat membrane-cross flow filtration system, the gel substance, which is the filter residue formed on the membrane surface, is quickly removed.
The relative velocity between the water to be treated and the membrane surface must normally be 2 m / sec or more, and a large amount of water to be treated is circulated compared to the permeated water, and the energy consumption of the pump for the circulation. Is big. As one of the measures to improve this, there is known a method of increasing the relative speed between the water to be treated and the membrane surface by rotating a membrane module in which a flat membrane is mounted on a disk. (See Proceedings of the Japan Society for Opportunity Society Environmental Engineering Symposium '91 p264-268)

[0006]

However, since the rotary flat sheet membrane module has a special shape and structure, a large-scale processing facility is remodeled regardless of the case of newly installing a small-sized processing apparatus as described in the above document. It is difficult to adopt it when newly installing.

For this reason, a general-purpose plate-shaped flat membrane or a box-shaped membrane module containing a plurality of plate-shaped flat membranes is used.
At the same time, there is a demand for a method of increasing the relative speed between the water to be treated and the film surface.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been invented in order to meet the above-mentioned needs, and a filtration membrane having flat filtration membranes mounted on both surfaces of a support plate having a passage for permeated water therein. It is characterized in that a plurality of units are arranged in parallel and suspended from above so that the filtration membrane becomes vertical and immersed in the wastewater containing activated sludge, and the permeate flow channel side is sucked while vibrating the filtration membrane unit. This is a cross-flow membrane filtration method for wastewater treatment.

The point of the present invention is to use a plate-shaped filtration membrane unit, which is a general-purpose product, or a box-shaped filtration membrane module containing a plurality of filtration membrane units. The point is to increase the relative speed of the membrane surface, prevent the accumulation of gel substances on the membrane surface, and perform wastewater treatment for a long period of time while maintaining the initial filtration capacity of the filtration membrane.

As the filtration membrane unit and the filtration membrane module in the present invention, general-purpose products developed for wastewater treatment are used. As the filtration membrane, flat membranes of ultrafiltration grade and microfiltration grade are used, and various synthetic polymer membranes, ceramics, and stainless steel membranes are used, but synthetic polymer membranes are used because of their availability and cost. Preference is given to using.

In the present invention, a general-purpose product, a filtration membrane unit in which flat filtration membranes are mounted on both surfaces of a support plate, or a filtration membrane module containing a plurality of the filtration membrane units in parallel is used. Since the filtration membrane unit or the filtration membrane module is vibrated considerably, it is necessary to carefully form it so as to withstand the vibration.

[0012] A plurality of filtration membrane units may be arranged in parallel and suspended from above so that the filtration membranes may be vertical, and each may be vibrated independently. A membrane module may be formed and the filtration membrane module may be vibrated. Sometimes, the entire plurality of filtration membrane units is divided into 2 to 3 to form 2 to 3 filtration membrane modules. You may vibrate each independently. Which method to use depends on the size and shape of the drainage pond,
It is determined in consideration of the size and shape of the filtration membrane unit.

In order to vibrate the filtration membrane unit or the filtration membrane module, the filtration membrane unit or the filtration membrane module is suspended from the upper support through a spring and attached to the upper surface of the filtration membrane unit or the filtration membrane module. A simple method is to operate the shaker.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the examples shown in the drawings.

1A and 1B show an example in which the present invention is carried out in a drainage aeration tank. FIG. 1A is a side view and FIG. 1B is a front view.

A plurality of (in this example, four) filtration membrane units 1a having flat filtration membranes 3 mounted on both surfaces of a support plate 2 having a passage 4 for permeated water therein are arranged in parallel in one fixed frame 5. The filtration membrane module 1 is fixedly formed. The flow path 4 is connected to the suction pump 14.

The filtration membrane module 1 is suspended from a filtration membrane support 9 which also serves as a lid of the aeration tank 6 via a plurality of springs 10, and a vibrator 11 is mounted on the upper surface of the fixed frame 5.
Is installed. In order to protect the spring 10 at the time of resonance, a damper 12 is provided between the support base 9 and the fixed frame 5.
Is installed. An air diffuser 8 is attached to the lower part of the aeration tank 6 so that the air becomes fine bubbles and jets into the water to be treated.

Waste water containing activated sludge is circulated and supplied to the aeration tank 6 to such an extent that the flat filtration membrane 3 is sufficiently immersed therein, and an air diffuser 8 is provided.
The air ejected from the air is contacted and aerated. In parallel with this, the filtration membrane module 1 vibrates violently up and down, and a part of the water to be treated is sucked by the suction pump 14 and permeates the flat filtration membrane 3 and passes through the flow path 4 to become permeated water which becomes an aeration tank. 6
It is discharged outside. Almost no accumulation of gel substance was observed on the surface of the flat filtration membrane 3, and a constant amount of permeated water was obtained for a long period of time.

FIG. 1 shows an example in which the filtration membrane module 1 is immersed in the aeration tank 6 to carry out membrane filtration of the water to be treated. However, due to the relationship between the volume of the existing aeration tank and the volume of the filtration membrane module, etc. When it is difficult to immerse the filtration membrane module in the aeration tank, a membrane filtration tank is provided separately from the aeration tank, and wastewater containing activated sludge after aeration treatment is circulated and supplied to the membrane filtration tank. Membrane filtration may be performed by immersing the filtration membrane module in.

FIG. 2 is a side view showing another embodiment. (The front view is omitted because it is almost the same as FIG. 1B.) The case of FIG. 2 is also an example of carrying out in the aeration tank for drainage, like the example of FIG. 1, and the installation of the filtration membrane module 1 of FIG. Instead of
In this example, four filtration membrane units 1a are independently installed in parallel. The flow path 4 inside the filtration membrane unit 1a is connected to a suction pump 14, and the filtration membrane unit 1a is suspended from a filtration membrane support base 9 also serving as a lid of the aeration tank 6 via a plurality of springs 10. The vibrator 11 is attached to the upper surface thereof. A damper (not shown) is attached to protect the spring 10 during resonance.
An air diffuser 8 is attached to the lower part of the aeration tank 6 so that the air becomes fine bubbles and jets into the water to be treated.

Wastewater containing activated sludge is circulated and supplied to the aeration tank 6 to such an extent that the flat filtration membrane 3 is sufficiently immersed therein, and an air diffuser 8 is provided.
The air ejected from the air is contacted and aerated. In parallel with this, four of the filtration membrane units 1a vibrate violently up and down independently, and a part of the water to be treated is sucked by the suction pump 14 and permeates the flat filtration membrane 3 and passes through the flow path 4. It becomes permeated water and is discharged to the outside of the aeration tank 6. Almost no accumulation of gel substance was observed on the surface of the flat filtration membrane 3, and a constant amount of permeated water was obtained for a long period of time.

[0022]

The present invention is constructed as described above and has the following effects.

(1) By constructing a vibration system, it becomes possible to obtain a sufficient relative velocity between the water to be treated and the flat filtration membrane surface with a small amount of energy, and it is possible to prevent the accumulation of gel substance on the membrane surface. Becomes

(2) By adopting the vibration system, it becomes possible to obtain a sufficient relative speed between the water to be treated and the flat filtration membrane surface by using a filtration membrane unit or a filtration membrane module which is a general-purpose product.

(3) Since the gel substance does not accumulate on the membrane surface, it becomes possible to membrane-filter the water to be treated having a high content of activated sludge.

(4) Since the filtration capacity of the flat filtration membrane hardly decreases, it is possible to secure a stable permeated water amount for a long period of time.

[Brief description of the drawings]

FIG. 1 shows an example in which the present invention is carried out in a drainage aeration tank,
(A) is a side view, (b) is a front view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Filtration membrane module, 1a ... Filtration membrane unit, 2 ... Filtration membrane support plate, 3 ... Flat filtration membrane, 4 ... Permeate flow path, 5 ... Fixed frame,
6 ... Aeration tank, 8 ... Air diffuser, 9 ... Filtration membrane support stand, 10 ... Spring, 11 ... Exciter, 12 ... Damper, 13 ... Anti-vibration rubber, 14 ... Suction pump.

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[Procedure amendment]

[Submission date] November 11, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 2

[Correction method] Added

[Correction contents]

FIG. 2 is a side view showing another example in which the present invention is carried out in a drainage aeration tank.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akimasa Ozawa 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd.

Claims (2)

[Claims] 1. An activated sludge in which a plurality of filtration membrane units having flat filtration membranes mounted on both surfaces of a support plate having a passage for permeated water are arranged in parallel and suspended from above so that the filtration membranes are vertical. A cross-flow membrane filtration method in wastewater treatment, characterized in that the permeated water flow path side is sucked while oscillating the filtration membrane unit while immersing it in wastewater containing. 2. The cross-flow membrane in wastewater treatment according to claim 1, wherein a plurality of filtration membrane units arranged in parallel are suspended from above as one filtration membrane module fixed to a fixed frame. Filtration method.