JPS594488A - Treatment of red tide - Google Patents

Abstract

PURPOSE:To recover effectively red tide planktons, by adding fine particles of a ferromagnetic material to red tidelike raw water, and subjecting the same to a centrifugal sepn. as it is when said fine particles are magnetized and after magnetizing the same when the particles are magnetized. CONSTITUTION:The raw water contg. red tide planktons from a red tide-like water area 1 is drawn through an intake line 2 and an intake device 3 into a stirring tank 5, where the raw water is stirred thoroughly with fine particles of a ferromagnetic material such as magnetite or the like from a mixing installation 4 and entangle and stick with and to each other. When the fine particles of the ferromagnetic material are magnetized with a magnetic field 7, the fine particles of the ferromagnetic material stuck with the red tide planktons are adsorbed to each other by the magnetic force of the particles themselves, thus forming flocs. The flocs are settled and separated in a settling tank 8, and are fed as a slurry through a line 10 to a centritugal separator 11, where the flocs are separated centrifugally, and are discharged as dehydrated slurry from a line 14. The desorbed water is returned to the tank 5 or the tank 8.

Description

[Detailed Description of the Invention] The present invention relates to a method for treating red tide, and in particular provides a method for eliminating red tide, which poses a pollution problem, and at the same time recovering red tide plankton, which is a causative agent of red tide, in a concentrated form by centrifugation. sen: means that.

Generally, when red tide plankton is centrifuged, an inorganic flocculant [Fe'(oH) 3° A7 (when dissolved in water) is used.
OH)3, etc.], extenders [e.g. 0aE10
4. CaO03,0a(OH)2 or clay] and a polymer flocculant (sodium alginate, etc.) are added, and the residence time in the centrifuge is set to 05 minutes or more and about 1 minute for dogs. However, in this case, there are disadvantages in that the quality of the desorbed water is poor (SS: 100 .mu./1 or more) and the discharged sludge concentration is low (60 .mu./1 or less).

The present inventors have developed a centrifugal separation method that eliminates the above drawbacks, has good quality of desorbed water, and has a high concentration of discharged sludge, thereby effectively recovering red tide plankton and As a result of intensive research to eliminate red tide, which is a pollution problem, we found that (a) the surface of red tide plankton is curved and many are covered with a film of mucus; (b) a large number of red tide plankton (C) Once ferromagnetic particles are magnetized, they attract each other with their own magnetic force, forming aggregates. (a) We confirmed the fact that all ferromagnetic particles have a large specific gravity and are very easy to settle in the field of centrifugal force, and we attached red tide plankton to ferromagnetic particles, We obtained the knowledge that red tide plankton could be collected efficiently in a concentrated form by centrifugation if they were made into aggregates by the magnetic force of the fine particles themselves, and after confirming this effect through many experiments, we developed the present invention. I have reached the point where I have completed the .

In short, the present invention provides a method for separating and recovering red tide plankton from red tide raw water, which includes taking red tide raw water,
A method for treating red tide, which comprises adding ferromagnetic particles to the mixture, and if the ferromagnetic particles have been magnetized in advance, they are left as is; if they are not magnetized, they are magnetized after the above addition, and then centrifuged. The gist is:

The present invention can also be applied onboard a red tide collection ship, and is generally advantageous in countermeasures against red tide plankton contamination in drinking water treatment, and in countermeasures against red tide plankton contamination when seawater, lake water is used as industrial water or industrial raw material. It can be applied to

Before describing the configuration of the present invention in detail, Table 1 first shows the structure of the present invention.

Hereinafter, the method of the present invention will be explained in detail with reference to the side drawings.

FIG. 1 is a flow sorting example showing an embodiment of the method of the present invention, and FIG. 2 is a flow sheet showing a partially modified example of FIG. 1.

In Figure 1.2, 1 is a red tide water area, 2 is a raw water intake line, 5 is a garbage removal/water intake device, 4 is equipment for mixing unmagnetized ferromagnetic particles, 5 is a stirring tank, and 6 is a water intake line. Stirrer (may be used as air stirring means), 7 is a magnetic field (magnetic field)
For example, a tunnel-shaped waterway made up of magnets or a waterway with a magnet inserted is used, 8 is a sedimentation tank, for example, natural sedimentation or a hydrocyclone is used, and 9
10 is the supernatant water discharge line, 10 is the slurry extraction line,
11 is a centrifuge, 12゜16 is a return line for desorbed water,
14 is a dewatered sludge discharge line.

The only difference between FIG. 1 and FIG. 2 is that the magnetic field 7 is located after the stirring tank 5 in FIG. 1, whereas in FIG. 2 it is located after the equipment for mixing ferromagnetic fine particles.

In Figure 1.2, raw water containing red tide plankton from a red tide-like water area 1 reaches a stirring tank 5 via a water intake line 2 and a water intake device 3, and is mixed with ferromagnetic fine particles [for example, magnetite] from a mixing equipment 4. (Fe3O4), hematite (Fe
2O3), oxides (rut, chromium oxide, etc.)
The ferromagnetic particles and red tide plankton become entangled with each other and land on each other. In the flow shown in Figure 1,
After this, when the ferromagnetic particles are magnetized in the magnetic field 7, in the flow shown in Figure 2, the ferromagnetic particles are magnetized and then supplied to the stirring tank 5, so the ferromagnetic particles with the red tide plankton attached are left as they are. The body particles attract each other by their own magnetic force and form aggregates. The flocs are sedimented and separated in a sedimentation tank 8, clean supernatant water is discharged from a line 9, and the flocs are sent as a slurry to a centrifuge 11 via a line 10.
After being centrifuged, it is discharged as dewatered sludge through line 14, and the dehydrated water is passed through line 12.13 to stirring tank 5.
Or it is returned to the sedimentation tank 8.

FIG. 3 is a flow sheet showing another embodiment of the method of the present invention, in which the same reference numerals as in FIG. 1.2 indicate the same functional parts as in FIG. 1.2, and 15 indicates solid-liquid separation. equipment (e.g., coagulation-sedimentation treatment equipment), 16 is an inorganic flocculant (used in the general method described above) and/or a polymeric flocculant (
a chemical injection device (used in the general method described above); 17 is a line for bypassing the settling tank 8;
It is sufficient to install only one of the magnetic fields 7a and '7b.

In the case shown in Fig. 3, before adding the ferromagnetic particles, the raw water containing red tide plankton is solid-liquid separated in advance using the solid-liquid separator 15, and the ferromagnetic particles are added to the slurry obtained here. As described above, the method of the present invention allows red tide plankton, which is extremely difficult to sediment in red tide waters, to settle down to 11n, to be absorbed by magnetized ferromagnetic fine particles. The ferromagnetic particles act as magnets and attract each other, forming huge aggregates.Furthermore, many ferromagnetic fine particles originally have a high specific gravity, and have very good sedimentation properties (sedimentation speed is several 1
0 m7'Hr ~ 100 m/'Hr), and if the ferromagnetic particles are magnetized, they become magnetized, and if they are not magnetized, they become magnetized, and the magnetized Red tide plankton is engulfed or adsorbed in aggregates made by magnetic fine particles, making it look like one.
Red tide plankton, which is difficult to sediment, can be easily centrifuged by turning them into two huge particles with high specific gravity and then centrifuging them (centrifugal separation).

Next, an experimental example of the method of the present invention will be given.

Example Plankton Test: Seawater collected from the Seto Inland Sea was supplemented with appropriate nutrients and vitamins, and cultured at around 25°C under strong light day and night.
) and some green algae and dinoflagellates.

Ferromagnetic fine particles Fe3O4 (magnetite) with a purity of 98% or more, true specific gravity 5.1 g/'rnl, average particle size 0.52 p, bulk specific gravity approximately 0.5 y/rn7! , magnetization 85.4 emu
/ ? (7koe, ) was used.

Centrifuge: A DeLaval type centrifuge with an internal volume t S t and a generated centrifugal force of 8400 G was used in a continuous liquid supply method.

Experimental result The results were as shown in Table 2.

In Table 2, in Comparative Example C, the ferromagnetic fine particles Fe3O4 were not magnetized, and in Inventive Examples A and B', the ferromagnetic fine particles Fe3O4 were not magnetized.
3O4 was used.

The following is clear from Table 2.

(a) Compared to Comparative Examples C and D, Examples A and B of the present invention have a greater treatment effect even if the residence time is shorter.

(b) The quality of desorbed water is about one order of magnitude better in Examples A and B of the present invention than in Comparative Examples C and D'.

(C) The discharged sludge concentration is almost twice as high as that of the comparative example in Inventive Example A, and even when Fe3O4 is added less as in Inventive Example B, it is 0. shows a significant difference to D,
The effect of concentrating the sludge in the example of the present invention was observed.

' As is clear from the above, it is clear that the method of the present invention can perform extremely effective treatment.

The effects of the method of the present invention detailed above are summarized below.

+11 A small centrifuge is sufficient (there is a difference in internal volume of 3 to 5 times compared to the general method described above).

(2) The discharged sludge concentration increases.

(3) The quality of the desorbed water is lower than that of the general method described above.
Approximately one order of magnitude better.

(4) By achieving the effects (1) to (3) above, red tide plankton, which has been difficult to concentrate in the past, can be concentrated extremely well.

[Brief explanation of the drawing]

1 to 6 are flow sheets showing embodiments of the method of the present invention. Sub-agent 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] In a method for separating and collecting red tide plankton from red tide raw water, red tide raw water is taken, ferromagnetic fine particles are added to it, and if the ferromagnetic fine particles are magnetized in advance, they must remain magnetized. For example, a method for treating red tide that uses a tube machine to magnetize after the above addition and then centrifuge it.