JP2018153742A - Water intake method, water intake device and water treating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water intake method, a water intake device and a water treating method capable of decreasing suspended matters and surfactant substances such as TEP which are contained in water with ease and a small-sized facility before water intake and reducing pretreatment operation on land.SOLUTION: A water intake method is characterized in blowing gas into water which is an intake object to generate bubbles, bringing the bubbles into contact with water to thereby adsorb contaminants contained in water on the bubbles and separate them and collecting water after separating the bubbles.SELECTED DRAWING: Figure 1

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 essential to take water from any water source, and it is necessary to take seawater, brackish water, fresh water, etc., and treat it according to the quality of the taken water and the purpose of use. is there. There are various substances in the water to be taken, and there are many substances that obstruct water treatment.

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

  Patent Document 1 discloses that in a seawater desalination apparatus using an RO membrane (reverse osmosis membrane), after taking seawater from a seawater intake facility, the TEP causes a blockage of the membrane before allowing the seawater to permeate the RO membrane. It is described that various pretreatments for removing are performed.

  Non-Patent Document 2 describes seawater desalination facilities in the Fukuoka metropolitan area. In this seawater desalination facility, the “osmotic water intake” method is adopted as a water intake method, and the seawater filtered by the seabed sand is pumped up 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 the sand at the bottom of the sea, thereby simplifying maintenance and management such as cleaning the inside of the pipe.

International Publication No. 2014/181585

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, “Case study of seawater desalination plant in Fukuoka area”, Journal “EICA”, 2011, Vol.15, No.4, P.48-51

  As described above, since seawater, brackish water, and fresh water contain various components that are unnecessary for obtaining the target treated water, it is necessary to remove unnecessary components in advance by pretreatment. This can be said to be an important process for reducing the burden of processing technology.

  In the invention described in Patent Document 1, it is described that the seawater taken from the sea is turbidized on land. However, when the seawater is desalted using a reverse osmosis membrane as in Patent Document 1, In order to maintain a high level of water quality, in addition to sand filtration on land, complex pretreatments that combine advanced techniques such as pressurized flotation and membrane filtration are required. As a result, there is a problem that the burden of pretreatment performed on land increases and the pretreatment equipment is enlarged.

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

  On the other hand, the water intake method that performs sand filtration 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 technique described in Non-Patent Document 2 requires a wide and stable sea bottom at the water intake location, so that there is a problem that the processing facility becomes large, and the construction cost and maintenance cost become enormous.

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

  In order to achieve the above object, the present inventors diligently studied.Before taking water, the gas was directly fed into the water to be taken to generate bubbles, and the pollutants contained in the water were adsorbed to the bubbles. It was found that it was effective to separate.

  The present invention completed on the basis of the above knowledge, in one aspect, generates bubbles by feeding gas into the water to be taken in water, and adsorbs pollutants contained in the water by bringing the bubbles into contact with water. Separating water and collecting water after separating the bubbles.

  In one embodiment of the water intake method according to the present invention, a water intake basin having a water inlet is arranged in the water to be water intake, and water is taken from the inlet into the water intake in a downward flow and from the lower part of the water intake basin. It includes bringing bubbles into contact with water in counterflow by generating bubbles and flowing the bubbles in an upward flow.

  In another embodiment of the water intake method according to the present invention, collecting the water separated from the air bubbles after contacting the air bubbles is less than the region where the air bubbles are in contact with the water in the water intake trough from the lower side of the water in the water intake trough. Including pumping up.

  In another embodiment of the water intake method according to the present invention, from the inside of the intake basin, the flow rate of the downward flow of water flowing into the intake basin is smaller than the rising speed of bubbles rising inside the intake basin. Includes drawing water.

  In another aspect, the present invention provides a water treatment method including pretreatment of water taken by the water intake method on land.

  According to still another aspect of the present invention, a water intake tub that is disposed in water to be water intake and has a water inlet, and a contaminant contained in the water by adsorbing the water in the water intake basin is adsorbed. There is provided a water intake device comprising a bubble generating means for generating bubbles and a water intake means for collecting water after separating the bubbles.

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

  In another embodiment of the water intake device according to the present invention, the water intake trough introduces water in a downward flow from the introduction port and causes the bubbles to flow upward from the lower portion of the water intake trough to the introduction port. An adsorbing / separating unit for bringing water and water into contact with each other in a counterflow, a degassing unit that communicates with the adsorbing / separating unit at the lower part of the intake trough, and bubbles and water are separated by the flow of each other, and intake water disposed in the degassing unit With piping.

  INDUSTRIAL APPLICABILITY According to the present invention, a water intake method and a water intake apparatus that can reduce surface active substances such as turbidity and TEP contained in water with simple and small equipment before water intake and can reduce pretreatment operations on land. And a water treatment method can be provided.

It is the schematic which shows an example of the water intake apparatus which concerns on embodiment of this invention. It is the schematic which shows an example of the water intake apparatus which concerns on the modification of embodiment of this invention. It is the schematic showing an example of the water intake apparatus which concerns on another modification of embodiment of this invention. It is a graph showing the relationship between the bubble rising speed and the bubble diameter. It is a graph showing transition of the test conditions of Example 1 and Comparative Example 1 and the concentration of pollutants in water taken, FIG. 5 (a) is the relationship between test time and aeration time, and FIG. 5 (b) is the test. FIG. 5C shows the relationship between the test time and the total organic carbon concentration (TOC), FIG. 5D shows the relationship between the test time and the dissolved organic carbon concentration (DOC), and FIG. (E) shows the relationship between test time and TEP concentration, respectively. It is a graph showing transition of the test conditions of Example 2 and Comparative Example 2 and the concentration of pollutants in the water taken, FIG. 6 (a) is the relationship between test time and aeration time, and FIG. 6 (b) is the test. FIG. 6 (c) shows the relationship between test time and total organic carbon concentration (TOC), FIG. 6 (d) shows the relationship between test time and dissolved organic carbon concentration (DOC), and FIG. (E) shows the relationship between the test time and the anionic surfactant concentration, and FIG. 6 (f) 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 parts are denoted by the same or similar reference numerals. The following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is to describe the structure, arrangement, etc. of components as follows. It is not something specific.

  As shown in FIG. 1, a water intake device according to an embodiment of the present invention has a water intake 1 having a water inlet 2 and contaminants contained in the water by contacting the water in the water intake 1. A bubble generating means 3 for generating bubbles 6 to be adsorbed and a water intake means 4 for taking water after separating the bubbles 6 are provided.

  The intake trough 1 has an introduction port 2 for introducing water to be taken into the inside, and has a structure in which inflow water flows from the introduction port 2 into the intake trough 1 in a downward flow. Although the specific shape of the intake trough 1 is not restrict | limited in particular, For example, the elongate cylindrical reaction tank which can be immersed in seawater, fresh water, or brackish water used as water intake object can be utilized. In the example of FIG. 1, the intake trough 1 extends from the bottom of the water to the surface of the water, and a part of the intake trough 1 is embedded in the bottom of the water, but may be arranged so as to achieve the object of the present invention. Of course, the arrangement is not limited to this.

  The bubble generating means 3 is a device for sending a gas into the water into the intake trough 1 to generate bubbles 6 in the intake trough 1. Water and bubbles introduced into the intake trough 1 from the inlet 2 by flowing the bubbles 6 upward from the bubble generating means 3 provided at the lower part of the intake trough 1 and raising the bubbles 6 toward the water surface. 6 can be brought into contact with each other in a counterflow.

The surface of the bubble ^{6, OH -, Cl -, COO} - is because of the negatively charged and concentrated, with a hydrophobic group in the contaminant such as turbid component, organics and oils that are introduced into the intake boxes 1 The substance is easily adsorbed on the surface of the bubble 6 by being electrically neutralized or repelled or ion-exchanged. Utilizing such properties, contaminants contained in water can be adsorbed by the bubbles 6 and separated.

  The bubble generating means 3 is preferably diffused by a blower such as a blower with a membrane-type air diffuser or a ceramic air diffuser, or air is sucked with an ejector or the like. Although air is generally used as the gas to be used, nitrogen or other gas may be supplied. That is, it is inexpensive to use air as the gas for forming bubbles, but it is not limited to any gas such as nitrogen gas, oxygen gas, ozone gas.

  The diameter (bubble diameter) of the bubbles 6 generated by the bubble generating means 3 varies depending on the properties of the water to be taken and the concentration and type of contaminants contained in the water, but the bubble diameter is 10 μm to 5 mm. It is preferable. When the bubble diameter is less than 10 μm, the rising speed of the bubbles is slow, and solid-liquid separation using the bubbles 6 may not proceed well. On the other hand, if the bubble diameter exceeds 5 mm, the bubble surface area sufficient for solid-liquid separation by bubbles cannot be secured, and the efficiency of solid-liquid separation may be reduced.

  Further, depending on the nature of the water to be taken in, preliminary bubble generating means (not shown) is used in combination, and the preliminary bubble generating means causes convection in the intake trough 1 or a bubble diameter different from the bubble generating means 3. You may generate bubbles. Thereby, it becomes possible to further improve the adsorption efficiency of contaminants in water.

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

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

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

  In order to prevent the bubbles 6 from being caught in the water intake means 4, as shown in FIG. 1, a partition plate 5 is arranged in the water intake trough 1, and a region separated from a region where many bubbles 6 exist by the partition plate 5. The water intake means 4 may be arranged inside. As shown in FIG. 2, the water intake trough 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 being mixed into the deaeration unit 11. Moreover, the efficiency of the adsorption separation process using the bubbles 6 can be further increased by setting the volume of the adsorption separation unit 10 to be larger than the volume of the deaeration unit 11.

  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 tank 1 to cause the bubbles 6 to flow upward. 6 and water are brought into contact in countercurrent. Thereby, the pollutant in inflow water is made to adsorb | suck to the bubble 6. FIG.

  The deaeration unit 11 communicates with the adsorption separation unit 10 at the lower portion of the intake tank 1. In the deaeration unit 11, the treated water after the contaminants are adsorbed and removed by the bubbles 6 is received, and 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 by the flow of each other, thereby functioning as a region for more completely removing the bubbles 6 from the water.

  In the deaeration unit 11, the flow rate of water in the deaeration unit 11 is adjusted to be lower than the rising speed of the bubbles 6, and the bubbles 6 are separated by rising to the water surface. By adopting such a configuration, the separation efficiency of the bubbles 6 is increased, and it is possible to prevent the bubbles 6 from being involved as much as possible when pumping water from the water intake means 4. In order to prevent the entrainment of the bubbles 6, the bubble intrusion suppression unit 12 for preventing the intrusion of bubbles may be formed around the water intake 41 of the water intake means 4. The configuration of the bubble intrusion suppression unit 12 is not particularly limited. The bubble intrusion suppression unit 12 may have a function of defoaming the bubbles 6.

  The water to be treated by the present invention is preferably seawater, fresh water, brackish water, etc., but is limited to this as long as it is a liquid that contains a contaminant and can remove the contaminant by bubble separation. It is not a thing.

  For example, oil-containing wastewater such as associated water, lake water containing algae, factory wastewater, and the like can be used as treatment targets. Examples of pollutants contained in water to be taken in include, but are not limited to, turbid substances that cause membrane clogging in 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, the water intake tub 1 is immersed in the water to be water intake, and after the contaminants are separated using the air bubbles 6 in the water intake basin 1, the air bubbles are removed. The treated water after separating 6 is taken. In this way, by performing the treatment according to the present embodiment before pumping up the water to be taken up to land, the burden of pretreatment for water treatment performed on land after that can be reduced.

  For example, when the foam separation process is adopted on land for the purpose of reducing TEP or the like, the foam generated by the foam separation process must be separated and processed. According to the present invention, the bubbles 6 adsorbing contaminants in the water can be returned as they are to the water to be taken from the inlet 2 by buoyancy, so that the bubbles 6 adsorbing contaminants can be treated separately. There is no need to provide means, and processing can be performed more efficiently. In addition, the intake trough 1 does not require a wide and stable sea bottom as in the case of filtration in water as described in Non-Patent Document 2, so it is easy to install and excellent in removing pollutants. A water intake device can be provided.

  As membrane fouling substances, dissolved organic matter and the water quality of the water intake location have an effect, and high turbidity raw water may cause membrane clogging. According to the water intake device and the water intake method according to the present embodiment, since contaminants that become membrane fouling substances can be removed in advance before water intake, pretreatment even when water is taken and pretreatment is performed on land. The burden can be reduced.

  Therefore, water treatment can be carried out in a particularly stable manner by introducing pretreated water that has been taken into water treatment equipment that performs water treatment using membrane separation or the like. . In addition, the water intake apparatus and the water intake method according to the present embodiment are suitably used for facilities that require various types of water intake, such as seawater desalination, salt production, aquaculture, fish business such as aquariums, city area business fields, and water purification plants. is there.

  Examples of the present invention will be described below 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 invention.

Example 1
The water intake apparatus shown in FIG. 3 was immersed in seawater to perform a water intake operation. As shown in FIG. 3, an opening was provided from the reference surface (AP: Arakawa construction reference surface) to a depth of 4.0 m, and seawater was allowed to flow into the water tank 1 using this as an inlet 2. The intake trough 1 was arranged so that the bottom face came to a depth of 7.0 m from the reference plane, and the bubble generating means 3 was arranged at a depth of 6.0 m from the reference plane. The water intake 41 of the water intake means 4 was arranged so as to be about 0.5 m below the bubble generating means 3 (a depth of 6.5 m from the reference surface). A ceramic air diffuser that generates bubbles with a bubble diameter of 100 μm (product specification) is used as the bubble generating means 3, the water intake amount from the water intake means 4 is 20 L / min, and the air diffuse amount from the bubble generator means 3 is 10 L / min. Minutes. The intake pipe diameter was 50 mm, and the sectional area of the intake trough 1 was 1 m ² .

  As shown in FIG. 5 (a), aeration is repeated every hour, turbidity with and without aeration, total carbon concentration (TOC), dissolved organic carbon concentration (DOC), ex vivo secretory polymer particles Changes in (TEP) concentration over time were observed. The results are shown in FIGS. 5 (b) to 5 (e). In this example, the TOC in the taken water was analyzed by a TOC analysis method using a combustion oxidation system, and the DOC was analyzed by the above-described TOC analysis method using a filtrate filtered through a glass filter having a pore size of 1 μm. TEP is obtained by filtering a seawater sample with a filter paper made of polycarbonate having a pore diameter of 0.4 μm, staining the sample captured on the surface of the filter paper with Alcian blue, and measuring xanthan gum (XG) as a standard with a spectrophotometer. Is expressed 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 when Example 1 is used as the case where the air is diffused and Comparative Example 1 is the case where the air is not diffused.

  As shown in Table 1, according to Example 1, the result that turbidity in seawater was reduced and TOC and DOC, which are organic substances, were also reduced. In Example 1, the turbidity was reduced to 51% and TEP to 37% as average values.

(Example 2)
The water intake apparatus shown in FIG. 3 was applied to water intake for water purification. In Example 2, as shown in FIG. 6 (a), the aeration is repeated every 24 hours, the turbidity with and without the aeration, the total carbon concentration (TOC), the dissolved organic carbon concentration (DOC), Changes in the anionic surfactant concentration and the in vitro exocrine 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 intake was 10 L / min, and the amount of air diffused from the bubble generating means 3 was 5 L / min. The intake pipe diameter was 25 mm, and the cross-sectional area of intake pipe 1 was 0.5 m ² . Other conditions are the same as in the first embodiment.

  Table 2 shows the average water quality values of Example 2 and Comparative Example 2 when Example 2 is used and Example 2 is the case when no air is diffused.

  As shown in Table 2, the turbidity, TOC, DOC, anionic surfactant, and TEP were all reduced by Example 2. Moreover, in Example 2, turbidity was reduced to 45%, TOC was 58%, DOC was 41%, and TEP was 40% as an average value. The anionic surfactant was detected for 6 days during the period in Comparative Example 2, but never detected in Example 2.

DESCRIPTION OF SYMBOLS 1 ... Water intake 2 ... Inlet 3 ... Bubble generation means 4 ... Water intake means 5 ... Partition plate 6 ... Bubble 10 ... Adsorption separation part 11 ... Deaeration part 12 ... Bubble invasion suppression part 41 ... Water intake

Claims (8)

  After the gas is sent into the water to be taken in to generate bubbles, the bubbles are brought into contact with the water to cause the contaminants contained in the water to be adsorbed and separated, and after the bubbles are separated Water intake method characterized by collecting water.   A water intake basin having a water introduction port is disposed in the water to be taken, and the water is taken down into the water intake basin from the introduction port and the bubbles are generated from the lower portion of the water intake basin. The water intake method according to claim 1, comprising bringing the bubbles and the water into contact with each other in a counterflow by flowing the water in an upward flow.   The sampling of water separated from bubbles after contacting with the bubbles includes pumping up water in the intake basin from below the region where the bubbles contact the water in the intake basin. The water intake method according to 2.   The water is drawn out from the intake basin so that the flow velocity of the downward flow of the water flowing into the intake basin is smaller than the rising speed of bubbles rising in the intake basin. The water intake method according to any one of the above.   The water treatment method including pre-treating the water taken in by the water intake method of any one of Claims 1-4 on land. An intake trough disposed in the water to be withdrawn and provided with a water inlet;
Bubble generating means for generating bubbles for adsorbing contaminants contained in the water by contacting the water in the intake trough;
A water intake device comprising: water intake means for collecting water after separating the bubbles.   The water intake device according to claim 6, wherein a water intake port of the water intake means is disposed below the bubble generating means in the water intake trough. The intake trough is
Adsorption separation in which the bubbles and the water are brought into contact with each other in a counter flow by introducing the water from the introduction port in a downward flow and flowing the bubbles in an upward flow from the lower part of the intake trough to the introduction port. And
A deaeration unit that communicates with the adsorption separation unit at a lower portion of the water intake trough, and in which the bubbles and the water are separated by a flow of each other;
The water intake device according to claim 6, further comprising: a water intake pipe disposed in the deaeration unit.