JPH0924250A - Treatment of raw water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain treated water in a simple device by which treatment efficiency is high and a contaminant is removed and transparency is high by immersing a membrane module in water to be treated in which activated carbon is dispersed in raw water and performing suction and filtration to obtain treated water. SOLUTION: Water 3 to be treated is obtained by mixing activated carbon slurry with raw water to be treated in a mixer 1. This water 3 to be treated is led to a vessel 2 and treated water is obtained by sucking and filtrating water 3 to be treated through a hollow yarn membrane module assembly in which a plurality of pieces of hollow yarn membrane elements consisting of an immersed hollow yarn membrane 4 and a stationary member 5 are combined. In such a way, water 3 to be treated is treated with good treatment efficiency and removal efficiency by using a small amount of activated carbon and high-grade treated water is obtained. A sheetlike hollow yarn membrane is suitably desirable as the used membrane module and an obstacle is not caused even in the case of merely arranging the hollow yarn membrane but the sheet is fixed from handling easiness. The sheetlike hollow yarn membranes are desirably arranged as equally as possible from an aspect increasing filtration efficiency. Polyethylene or the like are used in particular as the separation membrane and further the loadings of activated carbon is favorably 5-10wt.% for raw water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment method suitable for highly treating raw water such as river water, industrial waste water, industrial water, industrial waste water and secondary treated water of domestic waste water.

[0002]

2. Description of the Related Art Conventionally, a membrane module has been widely used in the field of so-called microfiltration such as aseptic water, drinking water, production of high-purity water, and air purification. Various studies have been conducted for solid-liquid separation in biological treatment such as treatment and tertiary treatment.

For these treatments, mainly microfiltration membranes,
An ultrafiltration membrane is used. These separation membranes are used in the form of flat membranes, tubular membranes or hollow fiber membranes.

Recently, the hollow fiber membrane is attached to a frame member to open both ends or one end for the purpose of preventing the substance to be filtered between the hollow fiber membranes from being blocked while ensuring the surface area of the hollow fiber membranes. A large number of hollow fiber membranes are arranged in a row, both ends are supported and fixed by upper and lower molds, and hollow fiber membrane filtration members having a filtrate passage communicating with the large number of hollow fiber membranes are continuously provided at predetermined intervals. At the same time, a hollow fiber membrane filter connected to each filtrate passage (Japanese Utility Model Laid-Open No. 5-63632, Japanese Patent Laid-Open No. 22022057/1990).
No. gazettes) are proposed.

Further, the hollow fiber membranes are arranged in a sheet form, and one end portion or both end portions of the hollow fiber membranes are fixed by fixing members in one or two different housings while keeping open states, respectively. There is proposed a hollow fiber membrane module (Japanese Patent Laid-Open No. 5-220356) in which the shape of the cross section of the fixing member perpendicular to the hollow fiber membrane is elongated and substantially rectangular.

In such a sheet-shaped flat hollow fiber membrane module, it is possible to evenly arrange the hollow fiber membranes with a space between the layers, and at the time of cleaning the membrane surface, the hollow fiber membrane surface is uniformly washed. Since it is extremely easy to do so, it is a module suitable for filtering highly polluted water, which can suppress a decrease in filtration efficiency.

[0007]

DISCLOSURE OF THE INVENTION The present invention has a low concentration of COD (consumption amount of potassium permanganate) contained in raw water such as river water, industrial wastewater, industrial water, industrial wastewater, and secondary treated water of domestic wastewater. , Water, odor, color, trihalomethane and precursors, surfactants, turbidity components, etc. are removed to produce waterworks by purification of river water, recovery and reuse of purified water by advanced treatment of industrial wastewater, purification of industrial water Process water and drinking water.

[0008]

Such an object is achieved by the following inventions. (1) A method for treating raw water, characterized in that treated water is obtained by suction filtration with a hollow fiber membrane module immersed in treated water in which activated carbon is dispersed in raw water.

(2) The treatment method according to (1) above, wherein the membrane module is a hollow fiber membrane module.

(3) A hollow fiber membrane module in which a hollow fiber membrane module is fixed by a fixing member so that both end portions of a sheet-shaped hollow fiber membrane are in an open state and the shape of both end portions is elongated and substantially rectangular. The processing method according to (2) above, wherein a plurality of the above are combined.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As the activated carbon of the present invention, granular activated carbon, crushed carbon, powdered activated carbon or the like can be appropriately used, but in order to achieve the object of the present invention, in order to increase the contact efficiency with a substance to be treated Powdered activated carbon is most suitable because it is dispersed and suspended in raw water and is easy to inject. The particle size is not particularly specified, but the average particle size is 10 to 50 μm and 1 μm.
It is desirable that the number of m or less is as small as possible.

The amount of activated carbon used depends on the pollutant concentration of the water to be treated, but it is several ppm to 500 pp relative to the raw water.
The amount of m is preferably 10 to 100 ppm, usually 10 to 30 ppm for removing off-flavors, and 30 to 100 ppm for removing trihalomethane precursor. If it exceeds 500 ppm,
Economically disadvantageous compared to other treatment methods.

In the method of the present invention, the separation membrane to be immersed in the water to be treated is a flat membrane if it is constructed so that raw water permeates from the outside of the membrane to the inside by suction to function as a separation membrane. Any material such as a tubular membrane and a hollow fiber membrane may be used.

From the viewpoint of easy handling and effective utilization of the entire membrane area, hollow fiber membranes are arranged in a sheet form and expanded to form a hollow fiber membrane element, and the hollow fiber membranes are evenly distributed in the water to be treated. Those that can be placed in

The membrane module of the present invention is preferably a sheet-shaped hollow fiber membrane, and a simple arrangement of the hollow fiber membranes may be used, but it is easy to handle and the filtration efficiency by fixing the shape of the sheet. From the standpoint of improving the above, it is preferable to arrange them as evenly as possible.

In this case, the sheet is placed vertically and the hollow fiber membranes are placed horizontally or vertically.

The present invention will be specifically described below with reference to the drawings. FIG. 1 is a conceptual diagram showing a preferable flow sheet for carrying out the processing method of the present invention.

Water to be treated 3 obtained by mixing raw water to be treated with 5 to 10 wt% of activated carbon slurry in a mixer 1 is introduced into a container 2 and immersed in a hollow fiber membrane (the surface of the membrane is subjected to ethylene-vinyl alcohol copolymerization). The treated water is obtained by suction filtration with a hollow fiber membrane module assembly in which a plurality of hollow fiber membrane elements consisting of a polyethylene hollow fiber membrane (4) covering a united body and a fixing member 5 are combined.

At this time, an air diffusing pipe 6 is provided below the hollow fiber membrane module assembly to perform air bubbling, and the water to be treated is stirred to uniformly disperse the activated carbon, and at the same time, the membrane module is blocked by the activated carbon. Prevent.

In the hollow fiber membrane module assembly of the present invention, it is preferable that the distance between the adjacent sheets is small in view of compacting the treatment tank and efficient air scrubbing. Clogging is likely to occur due to sludge, and it becomes difficult for bubbles to pass between the elements. On the other hand, if it is too wide, the compactness is lost, and it becomes difficult for bubbles to come into contact with the film surface, and the air scrubbing effect is impaired.

Therefore, an appropriate space is required for the space between the elements, and the conditions such as the size of the hollow fiber membrane occupying the module, the number of elements, the diameter of the water collecting pipe, air scrubbing, and backwashing are taken into consideration. It is necessary to select the distance, and the interval is preferably 5 to 100 mm, more preferably 5 to 70 mm
The range of mm is appropriate.

According to the method for treating raw water of the present invention, the permeation flux can be kept high for a long period of time under a filtration condition with a small differential pressure even when suction filtration is continuously carried out through the separation membrane.
Also, a so-called intermittent suction operation method of temporarily suspending suction can be adopted. Further, if necessary, the separation membrane element can be backwashed with the membrane-permeated water.

As the separation membrane, various ones can be used. For example, those made of various materials such as cellulose-based, polyolefin-based, polyvinyl alcohol-based, polysulfone-based, etc. can be used, and particularly strong stretch such as polyethylene and polypropylene. It is preferable to use a material of high degree.

The pore structure, pore diameter, porosity, film thickness, etc. are not limited as long as they can be used as a separation membrane, but as an example of a preferable porous separation membrane, the pore diameter is preferably 0.01 to 1 μm. Is 0.03 to 0.4 μm, which is smaller than the activated carbon particle size used, and has a porosity of 20 to 90% and a film thickness of 5 to 300 μm. In the case of a hollow fiber membrane, an outer diameter of 20 to 2000 μm is desirable.

At the same time, for the purpose of removing bacteria, it is essential that the pore size is 0.2 μm or less, and for the purpose of removing organic substances and viruses, the molecular weight cutoff is from tens of thousands to several tens. In some cases, an ultrafiltration membrane is used.

The surface property of the film material is preferably a so-called permanent hydrophilic film having hydrophilic groups on the surface. As a method for producing the permanent hydrophilic membrane, known methods such as a method for producing a hollow fiber membrane with a hydrophilic polymer such as polyvinyl alcohol or a method for hydrophilizing the surface of a hydrophobic polymer membrane can be used.

For example, when a hydrophilic polymer is applied to the membrane surface to hydrophilize the hydrophobic hollow fiber membrane, examples of the hydrophilic polymer include:
Saponified ethylene-vinyl acetate copolymer (= ethylene-
Vinyl alcohol copolymer), polyvinylpyrrolidone and the like.

The membrane obtained by hydrophilizing the above-mentioned hydrophobic membrane with a hydrophilic polymer has an advantage that it can reduce the hydrophobic interaction with the organic matter and reduce the amount of the organic matter adsorbed on the membrane surface.

[0029]

Since the present invention is a simple device, it has a compact structure and high processing efficiency.
By reducing the amount of activated carbon used, it is possible to obtain highly transparent treated water from which pollutants have been removed, and it can be used as it is for domestic water supply, which greatly contributes to industry.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a preferred flow sheet for carrying out the processing method of the present invention.

[Explanation of symbols]

 1 Mixer 2 Container 3 Water to be treated 4 Hollow fiber membrane 5 Fixing member 6 Air diffuser

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Tateishi 3816 Noborito, Tama-ku, Kawasaki-shi, Kanagawa Mitsubishi Rayon Co., Ltd. Tokyo Technical and Information Center

Claims (3)

[Claims] 1. A method for treating raw water, wherein treated water is obtained by suction filtration with a membrane module immersed in treated water in which activated carbon is dispersed in raw water. 2. The treatment method according to claim 1, wherein the membrane module is a hollow fiber membrane module. 3. A hollow fiber membrane module comprising a hollow fiber membrane module, wherein both ends of a sheet-shaped hollow fiber membrane are kept open and fixed by a fixing member so that both ends are elongated and substantially rectangular. The processing method according to claim 2, wherein a plurality of pieces are combined.