JP3931279B2 - Water purification equipment for suspended solids - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a purification device for removing floating substances such as jellyfish and pollutants in seawater, and particularly for purification of floating substance-containing seawater suitable for thermal power plants, ironworks, oil refineries, petrochemical plants, chemical factories, etc. Relates to the device.
[0002]
[Prior art]
Seawater is taken in as cooling water at power plants, etc., but this seawater may contain suspended substances made of organic substances such as jellyfish, red tide, and blue sea bream.
Seawater containing such substances is in a eutrophied state with increased suspended matter (SS) and chemical oxygen demand (COD). It is necessary to remove and purify. Therefore, in general, a purification device for removing and purifying these substances in the first stage of introducing seawater is provided. FIG. 1 shows an outline of a power plant system. In the figure, 1 is a purification device and 2 is a power plant. The seawater 3 is introduced into the purification device 1 and the suspended solids are removed, and then supplied for the cooling water of the power plant 2.
[0003]
FIG. 2 shows a configuration of a conventional purification device used in the above power plant system or the like.
[0004]
Seawater 3 is introduced into the raw water tank 5 by a pump 4. The seawater 3 introduced into the raw water tank 5 is further guided by a pump 6 to a nitrification tank 7 for biological treatment. The nitrification tank 7 is fed with a nutrient 7 and is treated with microorganisms. Further, the seawater 3 is denitrified in a denitrification reactor 10 into which methanol is introduced from a methanol injection device 9, and passes through the re-aeration tank 11 in a tank 11 in which bubbles are formed, and then into the precipitation tank 12. Sent. In the sedimentation tank 12, suspended substances are precipitated by their own weight, the supernatant is sent to the sand filtration device 13, the filtered seawater is introduced into the activated carbon adsorption device 14, the backwash treatment is performed, and the treated water is discharged.
[0005]
As described above, conventional purification apparatuses purify seawater by combining a plurality of stages of precipitation treatment, biological treatment, and chemical treatment, or use any one of these treatments alone.
[0006]
[Problems to be solved by the invention]
However, since the conventional purification apparatus needs to perform precipitation treatment, biological treatment, and chemical treatment, it requires a large-scale device and a large installation area for performing these treatments. In addition, in order to perform biological treatment, the operation management is relatively difficult, and the treatment takes time. In addition, in an apparatus including a biological treatment unit, when it is operated for the purpose of removing jellyfish, it is operated only in summer. For this reason, the equipment became idle in the autumn and winter seasons, and when the season arrived, it took a long time (approximately one month) to start up the biological treatment, and there was a disadvantage that it lacked mobility. Furthermore, in order to perform these treatments, it takes time because the facilities are overwhelmed, so that there is a problem that the water to be treated is spoiled and the working environment is deteriorated.
[0007]
An object of the present invention is to provide a seawater purification device that can be simplified and reduced in overall structure, easy in operation management, and high in processing time.
[0008]
[Means for Solving the Problems]
The present invention has the following configuration in order to solve the above problems.
[0009]
(1) A floating tank that temporarily stores the acquired seawater as the liquid to be purified, a bubble generating unit that floats in the storage tank by introducing bubbles into the floating tank and attaching floating substances to the bubbles, and a floating that floats A separation unit for removing substances, and a pressurized flotation separation device comprising:
A film processing apparatus for separating by filtration and fining seawater and non clarifying seawater purification target solution suspended solids have been removed in the upper floatation separator a membrane,
An oxidation treatment device for oxidizing the clear seawater;
An agglomeration part that is provided in a preceding stage of the levitation tank and aggregates suspended solids in seawater by introducing a flocculant into a tank for storing seawater;
With
The aggregating portion includes first means for aggregating suspended solids including organic matter in seawater, and second means for increasing the efficiency of aggregation in the first means.
In the present invention, the floating substance is attached to the bubbles and floats, and is removed by the separation unit. This operation is a physical action in which bubbles are forcibly generated and a suspended substance is attached to the bubbles to float, so that it is different from precipitation treatment, biological treatment, and chemical treatment. In the next stage, the liquid to be purified from which suspended substances have been removed is filtered through a membrane , and physical treatment is performed to separate the clear seawater and non-clear seawater. Does not include chemical treatment. In the next stage, the clear seawater is oxidized to reduce the chemical oxygen demand (COD). Since this oxidation treatment only oxidizes organic substances, a large apparatus such as a precipitation tank is not necessary.
Moreover, seawater is once collected in the agglomeration part and then introduced into the pressure levitation separator. The agglomeration part aggregates floating substances to form a floc, and improves the efficiency of processing in a later process. That is, by guiding the floc to the pressurized levitation device, the adhesion of the floc to the bubbles is promoted, and as a result, the amount of floating substance that floats can be increased.
[0010]
As described above, the present invention does not require an expensive facility such as a sedimentation tank, and does not require a long time for processing or complicated or complicated operation management.
[0011]
(2) The oxidation treatment apparatus oxidizes the clear seawater by irradiating the clear seawater with ultraviolet rays.
[0012]
By oxidizing the organic substance in the liquid to be purified with ultraviolet rays, it is possible to reduce the size of the apparatus and increase the processing speed and ease.
[0013]
(3) The oxidation treatment apparatus oxidizes the clear seawater by injecting ozone into the clear seawater.
[0014]
By injecting ozone into the liquid to be purified, the oxidation of the organic matter can be promoted. The structure is simple because only the ozone injecting device is provided, and miniaturization and high-speed processing can be realized.
[0017]
( 4 ) A temporary storage group for seawater is provided between the pressurized flotation separator and the membrane treatment device.
[0018]
The pressurized flotation separation device and membrane treatment device are used to separate and remove suspended solids by physical action, and the processing speed is the conventional device that removes suspended solids by precipitation treatment, biological treatment, and chemical treatment. It is considerably faster than. For this reason, if there is a difference in processing speed between these two apparatuses, the processing efficiency is lowered. Therefore, in the present invention, a temporary storage unit for seawater is provided between the pressurized flotation separation device and the membrane treatment device, and this temporary storage unit is used as a buffer. Thereby, even if there is a difference in processing speed between these two apparatuses, it is possible to mitigate the decrease in the overall processing speed.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 is a horizontal view of a seawater purification apparatus according to an embodiment of the present invention.
[0020]
Seawater is introduced into the raw water tank 20 from a pump (not shown), and the liquid to be purified is taken from the raw water tank 20 by the raw water pump 21. The to-be-purified liquid taken in is guided to the pressurized flotation separator 22. The pressurized flotation separation device 22 includes a coagulation agitation tank 23, a flotation tank 24, a bubbling water production apparatus 25, and a scum rake 26.
[0021]
The simulated agitation tank 23 is composed of a rapid agitation tank 23a and a slow agitation tank 23b. The rapid agitation tank 23a is pumped with an aggregator 27 containing salt iron and caustic soda 29. supplied by 28 and the pump 3 0, the Yurusoku撹solder tank 23b polymer flocculant 31 is supplied by a pump 32. The pseudo-collecting agent 27 appropriately aggregates organic substances in order to effectively raise the scum in the subsequent floating tank 24. The caustic soda 29 is supplied as a neutralizing agent for adjusting the pH. Further, the polymer flocculant 31 functions as an agglomeration aid and increases the efficiency of scum generation. Further, a stirring blade 33 is disposed in the rapid stirring tank 23a, and a stirring blade 34 is disposed in the slow stirring tank 23b.
The rapid stirring tank 23a, the pseudo-collecting agent 27, the caustic soda 29, the pump 28, and the pump 30 correspond to the first means of the present invention, and the slow stirring tank 23b, the polymer flocculant 31, and the pump 32 are the same. This corresponds to two means.
[0022]
The bubble water production apparatus 25 generates ultrafine bubbles and introduces the bubbles into the levitation tank 24 together with the liquid to be purified from the pseudo-mixing and stirring tank 23. These are preferably introduced from the bottom surface of the levitation tank 24, so that aggregates (organic matter) in the liquid to be purified sufficiently adhere to the surface of the bubbles during the period until the bubbles rise, To be separated.
[0023]
A plate-shaped scum rake 26 is disposed on the floating tank 24 so as to be rotatable along the liquid surface. The motor 33 rotates the scum rake 26, and the scum rake 26 rotates on the liquid surface of the floating tank 24, thereby scooping up the scum floating on the liquid surface and discharging it to the scum outlet 35. The scum discharged to the scum outlet 35 is discharged to the scum tank 34 by the scum discharge pipe 36. Thereby, a considerable amount of the solid organic matter contained in the liquid to be purified is separated and discharged.
[0024]
FIG. 4 shows the state of air bubbles adhering to the aggregate in the levitation tank 24. Many ultrafine bubbles 38 are mixed in the liquid component 39, and aggregates 37 adhere to the surface of the bubbles 38. As shown in the figure, since the bubbles 38 are considerably smaller than the volume of the aggregate 35, a plurality of bubbles 36 are in contact with the aggregate 35. For this reason, the buoyancy of the aggregate can be sufficiently increased, and these can be collected on the liquid surface and extracted as a scum of a large lump of aggregate.
[0025]
The to-be-purified liquid from which the scum has been removed in the levitation tank 24 is once discharged to the to-be-purified liquid storage section 40, and a part of this is guided to the bubble water production apparatus 25 by the pump 41. For this reason, the bubble water supplied to the levitation tank 24 is the one in which ultrafine bubbles are formed in the clean liquid from which the scum has been removed.
[0026]
The liquid to be purified in the liquid to be purified storage unit 40 is guided to the treated water storage tank 50. The storage tank 50 functions as a buffer that functions to absorb the difference between the processing speed of the pressurized flotation separation device 22 and the processing speed of the membrane processing device 52 at the subsequent stage. Since both the pressurized flotation separation device 22 and the membrane treatment device 52 perform physical processing without using a precipitation facility or the like, the processing speed is high. Therefore, by providing the storage tank 50, it becomes possible to absorb the difference in processing speed.
[0027]
The liquid to be purified once stored in the treated water storage tank 50 is guided to the membrane treatment device 52 by the pump 51. This apparatus separates clear seawater and non-clear seawater by filtering the seawater from which suspended solids have been removed by the pressurized flotation separator with membrane osmotic pressure. The membrane treatment device 52 introduces the raw water tank 53, a pump 54 for taking out the liquid to be purified stored in the raw water tank, and introducing the liquid to be purified taken out by the pump 54 and clarified seawater and non-clarified seawater by osmotic pressure. A module 55 for separation and a compressor 56 for extruding organic substances adhering to the film surface downward by air are provided. In the backwash drain 57, the contaminated liquid containing the organic matter on the membrane surface is drained. In addition, filtration drainage and drainage drainage are also performed on the backwash drainage tank 57.
[0028]
The UV oxidizer 58 oxidizes the liquid to be purified from which organic substances have been removed as described above by ultraviolet irradiation, and performs oxidative decomposition of chemical oxygen demand (COD) derived from the organic substances. Since this UV oxidation device 58 only irradiates the liquid to be purified with ultraviolet rays, it does not become a large-scale one.
[0029]
With the above configuration, the suspended matter (SS) of organic matter is removed from the seawater taken into the raw water tank 20 by the following steps, and the chemical oxygen demand (COD) is reduced.
[0030]
First, the seawater is flocked by the agitation and stirring tank 23. The flock floats by adhering to the bubbles in the levitation tank 24 and becomes scum, and is removed by the scum rake 26. At this stage, a considerable amount of suspended matter (SS) contained in the liquid to be purified (seawater) is removed.
[0031]
Next, the liquid to be purified from which suspended substances (SS) have been removed in this manner is separated into clear seawater and non-clear seawater by osmotic pressure in the membrane treatment device 52. Unclear seawater is drained as filtered wastewater into the backwash drain 57, and only clear seawater is taken out. This treatment also removes very fine suspended matter (SS).
[0032]
In the next stage, the liquid to be purified from which most of the suspended matter (SS) has been removed is oxidized by ultraviolet irradiation, and the chemical oxygen demand (COD) is reduced.
[0033]
FIG. 5 shows the state of reduction of suspended solids (SS) and chemical oxygen demand (COD) in each step by the above apparatus. Even at the stage where the process of the film processing apparatus 52 in the third process is completed, the process is reduced from 430 mg / L to 70 mg / L or less. When the fourth step UV oxidation is performed, the chemical oxygen demand (COD) is reduced to <50 mg / L.
[0034]
It should be noted that other oxidation means can be used in place of the UV oxidizer 58. For example, the clear seawater can be oxidized by injecting ozone into the clear seawater. Such a device also only oxidizes the clear seawater, so it is not a big deal.
[0035]
【The invention's effect】
According to this invention, since the apparatus is small and uses a pressurized flotation separation apparatus and a membrane processing apparatus with a high processing speed, it does not require a large facility such as a sedimentation tank, and a long time is required for processing. There is nothing. Moreover, since no microorganisms are used, operation management is easy.
[0036]
Further, by oxidizing the organic substance in the liquid to be purified with ultraviolet rays or ozone, it is possible to easily reduce the size of the apparatus and increase the processing speed.
[0037]
Moreover, seawater can be once collected in the agglomeration part and then introduced into the pressurized flotation separator.
[0038]
In addition, by providing a temporary storage unit for seawater between the pressurized flotation separation device and the membrane treatment device, even if there is a difference in treatment speed between these two devices, the overall treatment speed is reduced. Can be prevented.
[Brief description of the drawings]
1 is a schematic diagram of a power plant system to which a seawater purification device is applied. FIG. 2 is a configuration diagram of a conventional seawater purification system. FIG. 3 is a diagram of a seawater purification device according to an embodiment of the present invention. Fig. 4 is a diagram for explaining the operation of the pressurized flotation separation device. Fig. 5 is a diagram showing a decrease in SS and COD in the nominal process.
22: Pressurized flotation separator 23: Coagulation stirred tank 24: Flotation tank 25: Bubble water production apparatus 52: Membrane treatment apparatus 58: UV oxidation apparatus

Claims (4)

A floating tank that temporarily stores the obtained seawater as the liquid to be purified, a bubble generating section that floats in the storage tank by introducing bubbles into the floating tank and attaching floating substances to the bubbles, and removing floating substances that have floated A pressure levitation separator comprising: a separation unit;
A film processing apparatus for separating by filtration and fining seawater and non clarifying seawater purification target solution suspended solids have been removed in the upper floatation separator a membrane,
An oxidation treatment device for oxidizing the clear seawater;
An agglomeration part that is provided in a preceding stage of the levitation tank and aggregates suspended solids in seawater by introducing a flocculant into a tank for storing seawater;
With
The said aggregation part is a purification apparatus of floating substance containing seawater containing the 1st means to aggregate the floating substance containing the organic substance in seawater, and the 2nd means to raise the efficiency of aggregation in the said 1st means .   The said oxidation treatment apparatus is a purification apparatus of floating substance containing seawater of Claim 1 which oxidizes this clear seawater by irradiating ultraviolet rays to clear seawater.   The said oxidation treatment apparatus is a purification apparatus of floating substance containing seawater of Claim 1 which oxidizes this clear seawater by inject | pouring ozone into clear seawater. The apparatus for purifying floating substance-containing seawater according to any one of claims 1 to 3, wherein a temporary seawater storage unit is provided between the pressurized flotation separator and the membrane treatment apparatus.

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