JP2772612B2 - Water filtration method containing dissolved manganese using permeable membrane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a permeable membrane such as a microfiltration membrane or an ultrafiltration membrane to filter water containing manganese, including groundwater, to produce water supply, industrial water, and industrial water. Water.

[0002]

2. Description of the Related Art Conventionally, attempts have been made to filter water, industrial water, industrial water, etc. using a microfiltration membrane or an ultrafiltration membrane. By the way, most of the raw water used for these contains iron and manganese, and some river water also contains manganese.

Generally, manganese is present in water in a dissolved state, and dissolved manganese cannot be removed by a permeable membrane as it is. In order to precipitate dissolved manganese so that it can be removed by the permeable membrane, oxidizing agents such as potassium permanganate and ozone can be used, but these oxidizing agents are expensive and difficult to maintain. There was a disadvantage.

[0004]

SUMMARY OF THE INVENTION Filtration through a permeable membrane
Compared to conventional sand filtration, it has the feature of a compact device scale and the feature of completely removing suspended substances such as turbidity and bacteria contained in raw water. There is a disadvantage that dissolved substances cannot be removed. On the other hand, the conventional filtration using manganese sand coated with manganese dioxide after injecting chlorine has a drawback that a high filtration rate cannot be obtained because the filtration resistance increases when there are many suspended substances in water. .

[0005]

The permeable membrane used for drinking water and industrial water, such as waterworks, is often a microfiltration membrane or an ultrafiltration membrane having a membrane pore size of 0.2 μm or less. Almost 100% of soluble substances can be removed, but almost no soluble substances can be removed.

[0006] Raw water used in these methods includes surface water and groundwater, and part of the surface water and most of the groundwater contain manganese that is higher than the standard value of tap water quality. Manganese is usually dissolved in an ionic state and cannot be removed by the above permeable membrane as it is.

[0007] Raw water sometimes contains insoluble substances such as turbidity and bacteria, as well as soluble iron, etc., which is precipitated by injection of a chlorinating agent or contact with air. , Becomes a non-soluble substance. However, manganese is not easily oxidized and precipitated with chlorine at around neutral pH.

[0008] On the other hand, a filter using a contact filter medium for removing manganese can remove manganese in raw water almost completely.
Since the surface layer of the filter medium is easily clogged by the insoluble material in the raw water, the filtration speed cannot be increased.
In many cases, only about m / day could be taken.

[0009] Manganese is not easily oxidized and precipitated with chlorine at around neutral pH, but is easily oxidized and precipitated with chlorine when manganese dioxide is used as a catalyst. Then, after injecting a chlorine-based oxidizing agent into the raw water, water is passed through a reaction tank in which manganese sand is laid, and is brought into contact with manganese sand, whereby manganese can be oxidized and precipitated. Thereafter, by filtering through a permeable membrane, manganese can be easily separated and removed.

[0010]

[Function] If water is passed in a reaction tank with manganese sand laid down, the surface of the sand layer will be blocked by other insoluble substances contained in the downflow and the filtration resistance will increase in a short period of time. I can't take speed. On the other hand, in the present invention, since there is a permeable membrane at the latter stage, it is not necessary to remove insoluble substances in the raw water in the reaction tank, and manganese may be simply precipitated by oxidation.

Since the precipitation of manganese in the presence of manganese dioxide is completed in a short time, if water is passed through the reaction tank in an upward flow, the manganese sand can be kept in a fluid state even if a large amount of insoluble substances flows. As a result, the removal rate of the insoluble material is reduced, but the manganese oxidative precipitation reaction can be performed. If manganese is oxidized and precipitated, it can be completely removed by a permeable membrane together with turbidity and bacteria in raw water.

The catalyst for oxidizing and depositing manganese is not necessarily manganese sand, but the manganese that is oxidized and deposited becomes manganese dioxide, and can be used as an autocatalyst. Specifically, by passing water through a reaction tank in which a slurry containing a small amount of manganese sand or manganese dioxide has been charged in advance, the dissolved manganese is oxidized and precipitated, becomes manganese dioxide, and floats itself as a reaction catalyst. This phenomenon is particularly remarkable when raw water contains a large amount of iron, and manganese can be oxidized and precipitated without using manganese sand.

[0013]

EXAMPLE The embodiment shown in FIG.
The present invention relates to a method for producing drinking water by removing ground water containing 0.5 mg / l of soluble manganese in a reaction tank provided with manganese sand by catalytic oxidative precipitation and then removing the oxidized water with a permeable membrane.

In the middle of the pipe through which the raw water flows from the raw water pipe 1,
Appropriate amount (free residual chlorine in final membrane filtered water is 0.1-0.5m
g / l of sodium hypochlorite 2) flows into the reaction tank 4 after being injected by the injection device 3. The reaction tank 4 is formed in a cone shape. The cross-sectional area increases toward the upper part and the filtration speed LV decreases,
Consideration has also been given to the effect of precipitating suspended substances in the tank 4.

In the case of raw water containing almost no substance other than manganese, the raw water may be formed in a shape having the same cross-sectional area as the top and bottom, such as a column. Immediately after the injection of sodium hypochlorite or at an early point in the reaction tank 4, the soluble iron is oxidized and precipitated.

The raw water flowing into the reaction tank 4 passes through the strainer 5 and the small gravel support layer 6, passes through the manganese sand layer 7 laid, and contacts the manganese sand. Using manganese or manganese dioxide which has already been oxidized and precipitated as a catalyst, oxidized and precipitated with chlorine.
Thereafter, it rises in the reaction tank 4 and flows out of the water passage gutter 8 into the primary treatment water tank 9. The primary treated water is pumped to the permeable membrane 11 by the permeable membrane pressurizing pump 10, becomes purified water after membrane filtration, and flows out of the treated water outlet pipe 12.

In the reaction tank 4, some of the suspended solids and oxidized precipitates in the raw water precipitate and may form a slurry, but when passing through these slurries, oxidation of soluble manganese occurs. By promoting the precipitation and the same effect as the high-speed coagulation sedimentation basin, the removal of suspended substances in the raw water is promoted and the effect of the permeable membrane is roughly filtered.

If a large amount of slurry accumulates in the reaction tank 4, the slurry drain valve 13 is opened at an appropriate time, and the concentrated slurry is discharged from the slurry distribution pipe 14 to the outside of the system. In the case where sediment which cannot be discharged is deposited in the reaction tank 4 or a large amount of manganese adheres to the manganese sand, the blower is used.
With 15, compressed air can be blown from the lower part inside the reaction tank 4 to fluidize and wash the manganese sand layer 7.

Next, in the embodiment shown in FIG.
The same reference numerals are given to the same or equivalent effect parts as in the embodiment, and the description is omitted.
Then, the inside of the reaction tank 4 is raised. The pressure of the permeable membrane suspended above the inside of the reaction tank 4, that is, the secondary pipe 17 of the hollow fiber type microfiltration membrane bundle 16 is reduced by the vacuum pump 18 and the suction water tank 19, and membrane filtration is performed using the pressure difference.
The membrane filtered water flows out of the system from the treated water outflow pipe 12. If a large amount of raw water flows in from the membrane filtration water,
It is discharged out of the system by 0. Other operations are the same as those in the embodiment shown in FIG.

[0020]

According to the method of the present invention, since the manganese sand filter medium is granular, when the raw water is passed in an upward flow, the space between the manganese sand filter medium particles expands (expansion of the filter medium layer), and the filter medium particles float. In this state, dissolved manganese is oxidized and precipitated while coming into contact with raw water, and most of the precipitated manganese dioxide is not adsorbed, but passes between manganese sand filter media and flows out of the reaction layer together with suspended solids. Therefore, it is effective in producing fresh water, industrial water, industrial water and the like.

[Brief description of the drawings]

FIG. 1 is a system diagram of one embodiment of the present invention.

FIG. 2 is a system diagram of another embodiment of the present invention.

[Explanation of symbols]

 4 Reaction tank 11, 16 Permeable membrane

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 9/00 502 C02F 9/00 502P 502R 503 503G 504 504B

Claims (2)

(57) [Claims] 1. A method of removing dissolved manganese contained in the raw water, the chlorine-based oxidizing agent is injected into the raw water passes a manganese sand contact filter media layer which is laid into the reaction vessel downwardly in upflow,該Rozai Dissolved manganese is precipitated in the layer, and the suspended matter in the raw water is settled and separated above the reaction tank. A method for removing dissolved manganese, characterized by filtering with manganese. 2. The method according to claim 1, wherein the permeable membrane is immersed in the upper portion of the reaction tank, and the pressure difference between the secondary side of the permeable membrane and the siphon water pressure or the secondary side of the permeable membrane is reduced. A method for removing dissolved manganese, comprising filtering dissolved manganese through a permeable membrane.