JP6598065B2 - Polluted water treatment method - Google Patents

Description

The present invention relates to a method for treating polluted water in rivers, dam lakes, cross-flow sedimentation ponds, and the like.

Conventionally, various methods are adopted as a method for treating contaminated water. For example, a cross-flow type sedimentation basin is a typical example. As a method for treating this cross-flow sedimentation basin, a flocculant was added and stirred at the inlet of the cross-flow sedimentation basin to form and enlarge flocs, and the enlarged flocs were allowed to settle in the sedimentation part. Usually, for example, an inclined plate or the like is provided at the sedimentation site.

However, all of the conventional methods had to add a flocculant throughout the treatment of the polluted water, greatly affecting the treatment cost.
The present inventor has conducted various studies on a method capable of clarifying the polluted water over a long period of time by reducing the amount of the flocculant used as much as possible. It was found that the purpose was achieved by using a specific device in combination with a specific equipment to be brought into contact with adhesion, and the present invention was completed.

That is, the present invention extends a slime formed body composed of at least one of a string-like material, a cotton lump-like material, and a net-like material so as to oppose the water flow in a method for treating flowing polluted water, This is a method for treating contaminated water in which a flocculant having viscosity when in contact with water is added to the front surface of the slime forming body until the slime adheres to the surface of the slime forming body.

According to the method of the present invention, it is possible to remove fine particles that are difficult to agglomerate, and since the addition of the aggregating agent can be done at the initial stage of the treatment, the amount of the aggregating agent can be greatly reduced, It can be clarified for a long time. Moreover, since the slime to be produced is tightened, the bulk density is large, and the subsequent dehydration process can be easily performed.

It is a section schematic diagram of a cross current sedimentation pond. It is a photograph which shows the state which the slime adhered to the surface of the slime support. It is a top view of a straight string-like object. It is a top view of a helical string. It is a front view of a cotton lump. It is a front view of a net-like thing. It is a front view of the slime formation object comprised with the helical string. It is a front view of the slime formation object comprised with the cotton lump. It is a microscope picture which shows the state in which diatoms formed the slime.

Next, the method of the present invention will be described taking a cross-flow sedimentation basin as an example.
FIG. 1 is a schematic cross-sectional view of a cross-flow sedimentation basin 1.
The cross-flow settling basin 1 includes a stirring unit 2 and a settling unit 3. The agitating unit 2 is provided with a diffuser tube 4. The tip 5 of the air diffuser 4 provided below the water surface is open, the other end of the air diffuser 4 is connected to the compressor 6, and the air supplied from the compressor 6 is the tip 5 of the air diffuser 4. Are released as bubbles.
Further, in the sedimentation part 3, for example, a slime forming body 8 suspended from the float 7 is provided so as to oppose the water flow, and is extended to the full width of the lateral flow sedimentation basin. The slime forming body 8 is preferably stretched multiple times at intervals.
Further, the stirring unit 2 is provided with a flocculant injection tank 9 for adding the flocculant solution.

Next, the method of the present invention will be described with reference to FIG.
The polluted water W is introduced into the inlet 10 of the cross-flow settling basin. The polluted water W flows from the charging unit 10 into the stirring unit 2. Since the inflowing polluted water W has generated air bubbles from the diffuser pipe 4, a circulating flow is generated below the surface of the water, and when the polluted water W is stirred and dissolved in water from the upper flocculant injection tank 9 here A viscous flocculant solution and / or certain organisms are added.

Examples of the flocculant having viscosity when in contact with water include naturally derived flocculants such as chitosan, alginsan and bio flocculants, and synthetic flocculants such as cationic, anionic and nonionic flocculants. Of these, naturally derived flocculants are preferred. Of the natural flocculants, chitosan is particularly preferable.
The concentration of the flocculant solution used is preferably 0.1 to 5% by weight. The addition amount of the flocculant solution is 0.1 to 5 mg / L, preferably 1 to 2 mg / L with respect to the contaminated water. Although the addition time of the flocculant solution varies depending on the turbidity of the contaminated water, generally, the addition of about 1 hour causes the slime to adhere to the surface of the slime forming body 8 as shown in FIG.
Moreover, the flocculant which has viscosity when it contacts water like chitosan can be used in powder form. As an addition method, it may be added by an appropriate method to at least one portion of the stirring section 2 and the precipitation section 3 or the entire precipitation section. In addition, when adding to the precipitation part 3, it is suitable to add between the slime support bodies 8 by which multiple expansion was carried out, respectively.

The polluted water is stirred and mixed together with the flocculated solution in the stirring unit 2, and then the pollutant having relatively large particles is flocked and settled.
When treating highly turbid water, it is preferable to use a naturally derived flocculant and an inorganic flocculant in combination. For example, an inorganic flocculant is added to the stirring part 2 and a naturally derived flocculant is used for the precipitation part 3.

As shown in FIG. 1, a slime forming body 8 is suspended from a float 7 in the precipitation portion 3 and is stretched in multiple layers so as to face the water flow.
As the string-like material constituting the slime forming body 8, various shapes such as a straight shape as shown in FIG. 3 and a spiral shape as shown in FIG. 4 can be used. Various shapes such as a round shape, a flat shape, a rope shape, a jute shape, an acton shape, a PD curl shape, and a bride shape can also be used.
In addition, examples of the material of the cotton lump as shown in FIG. 5 include natural fibers, synthetic fibers such as polyester and nylon.
Furthermore, as the slime forming body 8, a net-like material as shown in FIG. The opening of the net-like material is generally preferably about 20 to 40 mm.
And the slime formation body 8 of this invention can be comprised by combining the said string-like thing, the cotton lump-like thing, and the net-like thing individually or suitably. The slime forming body 8 has a water-permeable structure.
When a string-like object as shown in FIGS. 3 and 4 is used, a slime is formed by suspending it on a support 11 as shown in FIG. 7 or combining it with a net-like object and a cotton lump-like object. The body can be configured. When a cotton lump is used, it can be used in a state where it is connected to the support 11 with a string, or it can be configured in combination with a net and string.

When a flocculant and / or organisms are added, the slime adheres to the surface of the slime former 8. The slime grows in the form of a thread by the addition of a flocculant and / or organisms such as spiral fungi, ciliates, rhizopods, diatoms, etc., and eventually peels off from the slime former 8 and settles on the precipitation part 3. According to such a method of the present invention, fine particles, which have been difficult to remove in the past, are taken in to form a slime and can be easily removed.
Usually, even if the slime is peeled off, the slime is regenerated, but when a large amount of slime is peeled off at once, the clarification treatment is suitably carried out continuously by adding a flocculant each time. The water clarified in the sedimentation part 3 is discharged out of the apparatus.

Next, the present invention will be described with reference to examples.
Example 1
Polluted water W (turbidity 130 mg / L) is introduced into the stirring section of the cross-flow settling pond. A 0.1% chitosan solution is added to the stirring unit 2 from the flocculant injection tank 9 at a rate of 1 mL / L. The chitosan solution and the polluted water W are agitated by the circulating flow of bubbles generated from the air diffuser 4, and particularly large polluted particles are flocked and settled here. The treated water treated in the stirring unit is transferred to the precipitation unit 3. The treated water transferred to the precipitation unit 3 attaches and captures fine particles that have not yet been removed to the surface of the slime forming body 8. The surface of the slime forming body 8 grows in the form of a thread on the surface and elongates as the treatment time elapses, and peels off due to the resistance of the water flow or the like when it reaches a certain weight. The clear water treated in the sedimentation section 3 is discharged from the crossflow sedimentation basin. It was 3 mg / L when the turbidity of the treated water immediately after passing through this slime forming body 8 was measured.
In addition, chitosan powder was directly added to the stirring unit 2 and the same was performed. As a result, the turbidity of the treated water immediately after passing through the slime formed body 8 was 9 mg / L.

Example 2
As a result of performing in the same manner as in Example 1 except that nonionic flocculant N-500 (product of Sankyo Kasei Kogyo Co., Ltd.) was used instead of chitosan in Example 1, the turbidity of treated water immediately after passing through the slime formed body 8 The degree was 13 mg / L.

Example 3
Polluted water (turbidity 130 mg / L) is introduced into the stirring section of the cross-flow sedimentation pond. Water (1 mL / L) containing spiral fungi, ciliates, rhizopods, and diatom organisms is added to the stirring section together with contaminated water. The addition of water containing organisms is stopped when slime is formed on the surface of the slime former. If only contaminated water is subsequently introduced, the slime grown in a string shape adheres to the slime forming body. When a part of the slime at this time was taken and observed with a microscope, it was confirmed that diatom organisms formed slime as shown in FIG. The turbidity of the clear water thus treated was measured and found to be 65 mg / L.

7 ... Float 8 ... Slime formation

Claims (1)

In the method for treating contaminated water with a flow, a slime formed body composed of at least one of a string-like material, a cotton lump-like material and a net-like material is stretched so as to oppose the water flow, and the front surface of the slime formed material the method for treating polluted water, characterized in that the continuous processing by temporarily adding an aggregating agent having a viscosity when in contact with water.