JP6720104B2 - Water intake method and water intake device - Google Patents

Description

The present invention relates to a water intake method, a water intake device, and a water treatment method.

In order to use water, it is basically necessary to take in water from some source, and it is necessary to take in seawater, brackish water, fresh water, etc., and treat the water according to the quality of the water taken and the purpose of use. is there. There are various substances in the water that is taken in, and there are many substances that interfere with water treatment.

In Non-Patent Document 1, as a cause (foulant) of clogging (fouling) of a filtration membrane and a reverse osmosis membrane, a transparent and highly adhesive jelly-like organic substance contained in all natural waters (TEP (high in vitro secretion)). The existence of molecular particles has been recognized.

In Patent Document 1, in a seawater desalination apparatus using an RO membrane (reverse osmosis membrane), after the seawater is taken from the seawater intake facility, before the seawater is transmitted to the RO membrane, a TEP that causes clogging of the membrane. It is described to apply various pretreatments for removing the.

Non-Patent Document 2 describes a seawater desalination facility in the Fukuoka metropolitan area. In this seawater desalination facility, the "infiltration water intake" method is adopted as the water intake method, and the seawater filtered by the seabed sand is pumped to the land. As a result, clean seawater can be stably taken on land, and barnacles and mussel eggs adhering to the intake pipe are also filtered by sand on the seabed, which simplifies maintenance such as cleaning work inside the pipe.

International Publication No. 2014/181583

Transparent exopolymer particles: Potential agents for organic fouling and biofilm formation in desalination and water treatment plants,Edo Bar-Zeev et al., Desalination and Water Treatment 3 (2009) 136-142 Yukio Morita, “Operating case of seawater desalination plant in Fukuoka area”, Academic journal “EICA”, 2011, Vol. 15, No. 4, P. 48-51

As described above, seawater, brackish water, and fresh water contain various components that are unnecessary for obtaining the target treated water. It can be said that this is an important process for reducing the burden on the processing technology.

In the invention described in Patent Document 1, it is described that seawater taken from the sea is subjected to turbidity treatment on land, but when desalinating seawater using a reverse osmosis membrane as in Patent Document 1, In order to maintain high water quality, in addition to sand filtration on land, complicated pretreatment combining advanced techniques such as pressure flotation and membrane filtration is required. As a result, there is a problem that the burden of pretreatment performed on land increases and the size of the pretreatment facility increases.

The technology described in Non-Patent Document 1 has only knowledge about the causal relationship between TEP contained in all natural waters and membrane blockage, and does not mention any efficient water intake method or pretreatment technology. ..

On the other hand, the water intake method for performing sand filtration treatment on the seabed as in the invention described in Non-Patent Document 2 is advantageous in that the burden of pretreatment on land can be reduced. However, the method described in Non-Patent Document 2 has a problem that the treatment facility becomes large and construction cost and maintenance cost become enormous because a wide and stable sea bottom is required at the intake point.

In view of the above problems, the present invention is a water intake method capable of reducing surface active substances such as suspended matter and TEP contained in water before water with a simple and small facility, and reducing pretreatment operations on land. And a water intake device and a water treatment method.

In order to achieve the above object, the inventors of the present invention have diligently studied and, before water intake, generate gas bubbles by directly sending a gas into the water to be water intake, and adsorb pollutants contained in water to the air bubbles. We have found that separation is effective.

In one aspect of the present invention completed based on the above knowledge, a gas is sent into water to be taken as water to generate bubbles, and the bubbles are brought into contact with each other to adsorb contaminants contained in the water to the bubbles. Is provided, and the water is collected after the air bubbles have been separated.

In one embodiment of the water intake method according to the present invention, an intake box provided with a water inlet is placed in the water to be taken in, and the water is taken from the inlet into the intake box in a downward flow and from the bottom of the intake box. Generating bubbles and causing the bubbles to flow in an upward flow includes contacting the bubbles with water in a counter flow.

In another embodiment of the water intake method according to the present invention, it is possible to collect water separated from the bubbles after contacting the bubbles with water in the intake chamber from below a region where the bubbles contact the water in the intake chamber. Including pumping up.

In another embodiment of the water intake method according to the present invention, the downward flow velocity of the water flowing into the intake chamber is reduced from the intake chamber so as to be smaller than the rising speed of bubbles rising in the intake chamber. Includes drawing water.

According to another aspect of the present invention, there is provided a water treatment method including pretreatment on land of water taken by the water intake method.

In still another aspect, the present invention is for placing an intake chamber provided in water to be taken and having an inlet for water, and for adsorbing a contaminant contained in the water by contacting the water in the intake chamber. There is provided a water intake device including a bubble generation unit that generates bubbles and a water intake unit that collects water after separating the bubbles.

In one embodiment of the water intake device according to the present invention, the water intake port of the water intake means is arranged below the bubble generating means in the water intake chamber.

In another embodiment of the water intake device according to the present invention, the intake chamber introduces water in a downward flow from the introduction port and causes bubbles to flow in an upward flow from the lower part of the intake chamber to the introduction port to form bubbles. And the water that come into contact with each other in a counter flow, the degassing section that communicates with the adsorption and separation section in the lower part of the intake chamber, and the bubbles and water are separated by each other's flow, and the water intake placed in the degassing section. And piping.

ADVANTAGE OF THE INVENTION According to this invention, surface-active substances, such as turbidity and TEP, contained in water can be reduced by simple and small equipment before water, and the pretreatment operation on land can be reduced and the water intake apparatus. And a water treatment method can be provided.

It is a schematic diagram showing an example of a water intake device concerning an embodiment of the invention. It is a schematic diagram showing an example of a water intake device concerning a modification of an embodiment of the invention. It is a schematic diagram showing an example of a water intake device concerning another modification of an embodiment of the invention. It is a graph showing the relationship between the rising speed of bubbles and the bubble diameter. It is a graph showing the transition of the concentration of pollutants in the water taken in and the test conditions of Example 1 and Comparative Example 1, FIG. 5 (a) is the relationship between the test time and aeration time, FIG. 5 (b) is a test Relationship between time and turbidity, FIG. 5(c) is a relationship between test time and total organic carbon concentration (TOC), FIG. 5(d) is a relationship between test time and dissolved organic carbon concentration (DOC), FIG. (E) shows the relationship between the test time and the TEP concentration. It is a graph showing the transition of the concentration of pollutants in the water taken in and the test conditions of Example 2 and Comparative Example 2, FIG. 6 (a) is the relationship between the test time and aeration time, FIG. 6 (b) is a test Relationship between time and turbidity, FIG. 6(c) is a relationship between test time and total organic carbon concentration (TOC), FIG. 6(d) is a relationship between test time and dissolved organic carbon concentration (DOC), FIG. 6E shows the relationship between the test time and the anionic surfactant concentration, and FIG. 6F shows the relationship between the test time and the TEP concentration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar reference numerals are given to the same or similar parts. The embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is that the structure, arrangement, etc. of components are as follows. It is not specific to one.

As shown in FIG. 1, the water intake device according to the embodiment of the present invention removes pollutants contained in the intake chamber 1 having a water inlet 2 and the water in the intake chamber 1 by contacting the intake chamber 1. A bubble generating means 3 for generating bubbles 6 for adsorption and a water intake means 4 for collecting water after the bubbles 6 are separated are provided.

The water intake 1 has an inlet 2 for introducing the water to be taken into the interior, and has a structure in which the inflow water flows from the inlet 2 into the water intake 1 in a downward flow. The specific shape of the water intake unit 1 is not particularly limited, but for example, a slender cylindrical reaction tank capable of immersing substantially the entire surface in seawater, fresh water, or brackish water to be taken in water can be used. In the example of FIG. 1, the intake box 1 extends from the water bottom to the water surface, and a part of the intake box 1 is buried in the water bottom, but the arrangement is such that the object of the present invention can be achieved. Of course, the arrangement is not limited to this.

The bubble generating means 3 is a device for sending gas into the water intake chamber 1 to generate bubbles 6 in the water intake chamber 1. Water bubbles introduced from the inlet 2 into the intake chamber 1 by causing the bubbles 6 to flow upward from the bubble generating means 3 provided in the lower part of the intake chamber 1 and raising the bubbles 6 toward the water surface. 6 can be contacted in counterflow.

Since OH ⁻ , Cl ⁻ , and COO ⁻ are concentrated and are negatively charged on the surface of the air bubble 6, contaminants such as turbid components, organic substances, and oil introduced into the intake chamber 1 have hydrophobic groups. The substance is electrically neutralized, repelled, or ion-exchanged, so that the substance is easily adsorbed on the surface of the bubble 6. By utilizing such a property, the pollutants contained in water can be adsorbed to the bubbles 6 and separated.

As the air bubble generating means 3, it is preferable to use a membrane type air diffuser or a ceramic air diffuser to diffuse air by a blower such as a blower, or to suck air by an ejector or the like to diffuse air. Air is generally used as the gas to be used, but nitrogen or another gas may be supplied. That is, it is cheap to use air as the gas for forming bubbles, but the gas is not limited to any gas such as nitrogen gas, oxygen gas, and ozone gas.

The diameter (bubble diameter) of the bubble 6 generated by the bubble generating means 3 varies depending on the nature of the water to be taken in and the concentration and type of the contaminant contained in the water, but the bubble diameter is 10 μm to 5 mm. It is preferable. If the bubble diameter is less than 10 μm, the rising speed of the bubbles may be slow, and solid-liquid separation using the bubbles 6 may not proceed well. On the other hand, when the bubble diameter exceeds 5 mm, it is not possible to secure a sufficient bubble surface area for solid-liquid separation by bubbles, and the efficiency of solid-liquid separation may decrease.

Furthermore, depending on the nature of the water to be taken in, a preliminary bubble generating means (not shown) is also used to generate convection in the intake chamber 1 by the preliminary bubble generating means, or a bubble diameter different from that of the bubble generating means 3. The bubbles may be generated. This makes it possible to further improve the adsorption efficiency of pollutants in water.

As the water intake means 4, for example, a water intake pipe extending along the longitudinal direction of the water intake box 1 is used. As shown in FIG. 3, the water intake 41 of the water intake means 4 is provided below the air bubble generation means 3, and the area in which the air bubbles 6 come into contact with water in the water intake chamber 1 through the water intake 41. Also, it is preferable to pump up the water in the intake chamber 1 from below (below the bubble generating means 3).

According to the water intake device shown in FIG. 3, it is possible to take in the water after contacting the air bubbles with a simple and small device without using a special device for separating the air bubbles from the water in the water container 1. it can.

The rising speed of the bubbles 6 in the water intake chamber 1 has a relationship as shown in FIG. 4 by the Stokes theorem when the water temperature is 20° C., for example. For example, when the bubble diameter is 1 mm (1000 μm), the rising speed of the bubble 6 is 32 m/min. In order to efficiently separate the inflow water and the bubbles 6 in the lower portion of the intake chamber 1, the water is drawn from the intake means 4 so that the downward flow velocity of the inflow water becomes smaller than the rising speed of the bubbles 6. It is preferable.

In order to prevent the air bubbles 6 from being trapped in the water intake means 4, as shown in FIG. 1, a partition plate 5 is arranged in the water intake means 1, and the partition plate 5 separates a region where a large number of air bubbles 6 exist. The water intake means 4 may be arranged inside. As shown in FIG. 2, the water intake chamber 1 may be divided into an adsorption/separation unit 10 and a deaeration unit 11 via a partition plate 5, and the water intake means 4 may be arranged in the deaeration unit 11. By arranging the lowermost end of the partition plate 5 below the bubble generating means 3, it is possible to prevent the bubbles 6 from mixing into the degassing section 11. Further, by making the volume of the adsorption/separation unit 10 larger than that of the degassing unit 11, the efficiency of the adsorption/separation process by the bubbles 6 can be further enhanced.

In the adsorption/separation unit 10, water is introduced from the inlet 2 in a downward flow, and bubbles are generated from the bubble generating means 3 in the lower part of the intake chamber 1 to cause the bubbles 6 to flow in an upward flow. 6 and water are brought into contact with each other in counterflow. As a result, the contaminants in the inflow water are adsorbed by the bubbles 6.

The degassing section 11 communicates with the adsorption/separation section 10 in the lower part of the intake chamber 1. In the degassing section 11, the treated water after the contaminants have been adsorbed and removed by the bubbles 6 is received, the treated water is caused to flow upward, and the bubbles accompanying the treated water are raised and sent to the water surface. That is, the bubbles 6 and the treated water are separated from each other by the flow of each other, thereby functioning as a region for more completely removing the bubbles 6 from the water.

In the degassing unit 11, the flow velocity of water in the degassing unit 11 is adjusted so as to be lower than the floating speed of the bubbles 6, and the bubbles 6 are separated by floating on the water surface. By adopting such a configuration, the separation efficiency of the bubbles 6 is improved, and it is possible to prevent the bubbles 6 from being caught as much as possible when the water is drawn from the water intake means 4. In order to prevent the entrainment of the bubbles 6, a bubble invasion suppressing portion 12 for preventing invasion of bubbles may be formed around the water intake 41 of the water intake means 4. The structure of the bubble invasion suppressing unit 12 is not particularly limited. The bubble invasion suppressor 12 may have a function of eliminating the bubbles 6.

The water to be treated by the present invention is preferably seawater, fresh water, brackish water, etc., but is not limited to this as long as it is a liquid containing a pollutant and capable of removing the pollutant by air bubble separation. Not a thing.

For example, oil-containing wastewater such as produced water, lake water containing algae, factory wastewater, and the like can also be used as treatment targets. Examples of pollutants contained in the water to be taken in include, but are not limited to, turbid substances that cause clogging of the membrane during membrane separation, organic components such as TEP, and the like.

According to the water intake device and the water intake method according to the embodiment of the present invention, after the water intake 1 is immersed in the water to be water intake and the contaminants are separated using the air bubbles 6 in the water intake 1, The treated water after separating 6 is taken up. As described above, by performing the treatment according to the present embodiment before pumping the water to be taken in to the land, it is possible to reduce the burden of the pretreatment for the subsequent water treatment performed on land.

For example, when the foam separation treatment is adopted on land for the purpose of reducing TEP and the like, the foam generated by the foam separation treatment must be separated and treated. According to the present invention, the bubbles 6 adsorbing contaminants in water can be directly returned to the water itself to be taken from the inlet 2 by buoyancy, so that the bubbles 6 adsorbing contaminants can be treated separately. It is possible to perform the processing more efficiently without providing any means. In addition, the intake chamber 1 does not require a wide and stable sea bottom as in the case of performing filtration in water as described in Non-Patent Document 2, and thus is excellent in ease of installation and removal of pollutants. A water intake device can be provided.

As a fouling substance of the membrane, dissolved organic matter and water quality at the intake point may affect, and high turbidity raw water may cause clogging of the membrane. According to the water intake device and the water intake method according to the present embodiment, it is possible to previously remove the contaminants that become the fouling substances of the membrane before water intake, so that even when water is taken and pretreatment is performed on land, The burden can be reduced.

Therefore, by pretreating the taken-in water and introducing the pretreated water into a water treatment facility that uses water treatment such as membrane separation, the water treatment can be carried out particularly stably. .. In addition, the water intake device and the water intake method according to the present embodiment are preferably used for seawater desalination, salt production, aquaculture, urban areas such as fish such as aquariums, water purification plants, and other facilities that require water intake. is there.

Hereinafter, examples of the present invention will be shown together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the present invention.

(Example 1)
The water intake device shown in FIG. 3 was immersed in seawater to perform water intake operation. As shown in FIG. 3, an opening was provided to a depth of 4.0 m from the reference surface (AP: Arakawa construction reference surface), and this was used as an inlet 2, and seawater was introduced into the water chamber 1. The water intake 1 was arranged so that the bottom surface came to a depth of 7.0 m from the reference surface, and the bubble generating means 3 was arranged to a depth of 6.0 m from the reference surface. The water intake 41 of the water intake means 4 was arranged to be 0.5 m below the bubble generating means 3 (depth of 6.5 m from the reference plane). As the bubble generating means 3, a ceramic air diffusing tube for generating bubbles having a bubble diameter of 100 μm (product specification) is used, the amount of water taken from the water taking means 4 is 20 L/min, and the amount of air taken from the bubble generating means 3 is 10 L/min. Minutes The diameter of the water intake pipe was 50 mm, and the cross-sectional area of the water intake chamber 1 was 1 m ² .

As shown in FIG. 5(a), air diffusion is repeated every hour, and turbidity with and without air diffusion, total carbon concentration (TOC), dissolved organic carbon concentration (DOC), ex vivo secretory polymer particles The change in (TEP) concentration with time was observed. The results are shown in FIGS. 5(b) to 5(e). In this example, TOC in the taken-in water was analyzed by the TOC analysis method by the combustion oxidation method, and DOC was filtered by a glass filter having a pore size of 1 μm, and the filtrate was analyzed by the above-mentioned TOC analysis method. TEP is a unit measured by filtering a seawater sample with a filter paper made of polycarbonate having a pore size of 0.4 μm, staining the sample captured on the filter paper surface with alcian blue, and measuring with xanthan gum (XG) as a standard by a spectrophotometer. Is shown in μg-XG/L. TEP quantified by this analysis method is an acidic mucopolysaccharide. Table 1 shows the water quality average values of Example 1 and Comparative Example 1, where the case of performing air diffusion is Example 1 and the case of not performing air diffusion is Comparative Example 1.

As shown in Table 1, the results obtained in Example 1 show that the turbidity in seawater is reduced and the TOC and DOC, which are organic matter amounts, are also reduced. In Example 1, the turbidity was reduced to 51% and the TEP was reduced to 37% on average.

(Example 2)
The water intake device shown in FIG. 3 was applied to water intake for water purification. In Example 2, as shown in FIG. 6( a ), air diffusion was repeated every 24 hours, and turbidity with and without air diffusion, total carbon concentration (TOC), dissolved organic carbon concentration (DOC), Changes in the anionic surfactant concentration and the in vitro secretory polymer particle (TEP) concentration over time were observed. The results are shown in FIGS. 6(b) to 6(f). In Example 2, the amount of water taken in was 10 L/min, and the amount of air diffused from the bubble generating means 3 was 5 L/min. The diameter of the water intake pipe was 25 mm, and the cross-sectional area of the water intake chamber 1 was 0.5 m ² . Other conditions are the same as those in the first embodiment.

Table 2 shows the water quality average values of Example 2 and Comparative Example 2, where the case of performing air diffusion is Example 2 and the case of not performing air diffusion is Comparative Example 2.

As shown in Table 2, Example 2 reduced turbidity, TOC, DOC, anionic surfactant, and TEP. In Example 2, the turbidity was reduced to 45%, the TOC was reduced to 58%, the DOC was reduced to 41%, and the TEP was reduced to 40% on average. The anionic surfactant was detected in Comparative Example 2 for 6 days during the period, but was never detected in Example 2.

DESCRIPTION OF SYMBOLS 1... Water intake 2... Inlet port 3... Air bubble generating means 4... Water intake means 5... Partition plate 6... Air bubble 10... Adsorption separation part 11... Degassing part 12... Air bubble invasion suppression part 41... Water intake

Claims (7)

An intake box having a water inlet is placed in the water to be taken in, and the water is taken in a downward flow from the inlet into the intake box and a gas is sent from the lower part of the intake box to generate bubbles. The bubbles are caused to flow in an upward flow, and the bubbles and the water are brought into contact with each other in an opposite flow to adsorb and separate the pollutants contained in the water from the bubbles, thereby adsorbing the pollutants in the water. A method of water intake, characterized in that the air bubbles are discharged from the inlet into the water to be water intake by buoyancy, and the water after the air bubbles are separated is collected. Taking a water separated from the bubbles after contact with the bubbles, to claim 1, wherein the bubble in said intake masses comprises pumping water in the water intake boxes from below the region in contact with the water Water intake method described. The flow rate of the downward flow of the water flowing into the water intake in trout, the intake as squares in smaller than the rising speed of the bubbles rise, according to claim 1 or 2 comprising withdrawing the water from the water intake inside boxes Water intake method described in. Water treatment method comprising pretreatment on land the intake water by intake process according to any one of claims 1-3. An intake box that is placed in the water to be taken and has a water inlet,
Bubble generating means for generating bubbles for adsorbing contaminants contained in the water by contacting with water in the water intake in a counter flow ,
Water intake means for releasing the air bubbles adsorbing the contaminants in the water from the inlet into the water to be water intake by buoyancy and collecting water after separating the air bubbles. apparatus. The water intake device according to claim 5 , wherein the water intake port of the water intake unit is arranged below the bubble generating unit in the water intake chamber. The water intake is
Adsorption separation in which the water and the water are brought into contact with each other in a countercurrent manner by introducing the water in a downward flow from the introduction port and causing the bubbles to flow in an upward flow from the lower part of the water intake chamber to the introduction port. Department,
A deaeration part that communicates with the adsorption separation part in the lower part of the water intake box and separates the bubbles and the water by mutual flow;
The intake system according to claim 5 or 6 , further comprising: an intake pipe arranged in the deaerator.