Purification method and purification device for emulsion-containing oily wastewater

Abstract

To purify emulsified oil-containing waste water to a higher level than before.SOLUTION: There is provided a purification method for recovering water from emulsified oil-containing waste water containing oil-in-water emulsion and separated oil not constituting emulsion, the method including: adding a flocculating agent to the emulsified oil-containing waste water to flocculate and remove the separated oil; adding an oil-water separating agent to the emulsified oil-containing waste water to break the emulsion; bringing the emulsified oil-containing waste water that has undergone flocculation and emulsion breakage into contact with activated charcoal so as to remove oil separated by the emulsion breakage by adsorption on the activated charcoal; and removing impurities by passing the emulsified oil-containing wastewater that has undergone the adsorption process through a reverse osmosis membrane. Prior to the adsorption step, a neutralizing agent may be added to the emulsified oil-containing waste water that has undergone the emulsion breaking step to bring pH of the emulsified oil-containing waste water closer to neutrality.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and apparatus for purifying emulsified oily wastewater. More specifically, the present invention relates to a method and apparatus for purifying emulsified oily wastewater that can purify the emulsified oily wastewater to a higher level than conventional methods.

Background Art

[0002] In recent years, reducing the environmental impact by reducing waste has become a major issue in the industrial world. Among them, in industries that generate oily wastewater, reducing the amount of oily wastewater discharged has become a major issue. For example, for car wash facilities that use a large amount of water, technologies have been proposed to efficiently remove oil and the like contained in the wastewater and enable reuse as washing water (see, for example, Patent Documents 1 and 2). Also, for factories that perform plastic processing and / or cutting using an emulsion as a lubricating oil and / or cutting oil, an oil-water separation method has been proposed that can efficiently separate the oil and water in the emulsified oily wastewater discharged from such factories (see, for example, Patent Document 3).

[0003] By the way, in factories where hydroforming is performed, an emulsion is widely used as a fluid (hereinafter sometimes referred to as "pressurized fluid") for applying high pressure inside a tubular workpiece (pipe). In the emulsified oily wastewater discharged from such factories, due to the high pressure applied during processing, the oil droplets (hereinafter sometimes referred to as "oil drops") that make up the emulsion are further refined. In addition, other oils and sludge used as lubricating oils and / or cutting oils may gradually mix into the emulsified oily wastewater. The oils thus mixed also become fine oil droplets due to the high pressure applied during processing and are dispersed in the emulsified oily wastewater. For such emulsified oily wastewater, it is extremely difficult to obtain water purified to a level that can be reused by the purification technologies according to the prior art as described above.

[0004] That is, in this technical field, there is a need for a technology capable of purifying emulsion-containing oily wastewater to a higher level than before.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, in this technical field, there is a need for a technology capable of purifying emulsion-containing oily wastewater to a higher level than before.

Means for Solving the Problems

[0007] Therefore, as a result of intensive research, the present inventor has found that emulsion-containing oily wastewater containing water droplet-type emulsions in water and separated oil that does not form an emulsion can be subjected to aggregation removal of the separated oil and emulsion destruction, and then passed through a reverse osmosis membrane after contacting with activated carbon, thereby obtaining water purified to a higher level than before.

[0008] Specifically, the method for purifying emulsion-containing oily wastewater according to the present invention (hereinafter may be referred to as "the method of the present invention") is a method for purifying emulsion-containing oily wastewater for recovering water from emulsion-containing oily wastewater containing water droplet-type emulsions in water and separated oil that is oil not forming an emulsion. The method of the present invention includes a coagulation step, an emulsion destruction step, an adsorption step, and a reverse osmosis step.

[0009] The flocculation step is a step of adding a flocculant to the emulsified oily wastewater to flocculate and remove the separated oil. The emulsion breaking step is a step of adding an oil-water separator to the emulsified oily wastewater to break the emulsion. The adsorption step is a step of bringing the emulsified oily wastewater that has undergone the flocculation step and the emulsion breaking step into contact with activated carbon to adsorb and remove the oil separated by emulsion breaking onto the activated carbon. The reverse osmosis step is a step of passing the emulsified oily wastewater that has undergone the adsorption step through a reverse osmosis membrane to remove impurities.

[0010] On the other hand, the purification device for emulsified oily wastewater according to the present invention (hereinafter, may be referred to as "the device of the present invention") is a device configured to carry out the method of the present invention described above. Specifically, the device of the present invention is a purification device for emulsified oily wastewater that recovers water from emulsified oily wastewater containing an oil-in-water type emulsion and separated oil that is not an emulsion-forming oil. The device of the present invention includes a flocculation section, an emulsion breaking section, an adsorption section, and a reverse osmosis section.

[0011] The flocculation section includes a flocculation tank that is a container for containing emulsified oily wastewater and a flocculant addition means configured to add a flocculant to the emulsified oily wastewater contained in the flocculation tank. The flocculation section is configured to execute a flocculation step of adding a flocculant to the emulsified oily wastewater by the flocculant addition means to flocculate and remove the separated oil.

[0012] The emulsion breaking section includes an emulsion breaking tank that is a container for containing emulsified oily wastewater and an oil-water separator addition means configured to add an oil-water separator to the emulsified oily wastewater contained in the emulsion breaking tank. The emulsion breaking section is configured to execute an emulsion breaking step of adding an oil-water separator to the emulsified oily wastewater by the oil-water separator addition means to break the emulsion.

[0013] The adsorption section includes activated carbon and an adsorption tank which is a container for housing the activated carbon. The adsorption section is configured to perform an adsorption process of adsorbing and removing the oil separated by emulsion destruction by bringing the emulsified oily wastewater that has undergone the aggregation process and the emulsion destruction process into contact with the activated carbon.

[0014] The reverse osmosis section includes a reverse osmosis tank which is a container whose internal space is partitioned by a reverse osmosis membrane, and a pressurizing means configured to apply pressure to the emulsified oily wastewater that has undergone the adsorption process and is housed on one side of the reverse osmosis membrane of the reverse osmosis tank. The reverse osmosis section is configured to perform a reverse osmosis process of removing impurities by passing the emulsified oily wastewater through the reverse osmosis membrane by applying pressure to the emulsified oily wastewater by the pressurizing means.

Advantages of the Invention

[0015] As described above, in the method and apparatus of the present invention, emulsified oily wastewater containing water-in-oil type emulsions and separated oil not constituting an emulsion is subjected to aggregation removal of the separated oil and emulsion destruction, and after being further brought into contact with activated carbon, it is passed through a reverse osmosis membrane. As a result, according to the method and apparatus of the present invention, water purified to a higher level than before can be recovered.

[0016] Other objects, other features, and attendant advantages of the present invention will be readily understood from the description of each embodiment of the present invention described with reference to the following drawings.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0018] 《First Embodiment》 Hereinafter, a method for purifying emulsion-containing oily wastewater (hereinafter, may be referred to as the "first method") according to the first embodiment of the present invention will be described with reference to the drawings.

[0019] 〈Configuration〉 The first method is a method for purifying emulsion-containing oily wastewater that recovers water from emulsion-containing oily wastewater containing water-in-oil droplets type emulsions and separated oil that is not an emulsion-forming oil. The first method includes a coagulation step, an emulsion breaking step, an adsorption step, and a reverse osmosis step.

[0020] FIG. 1 is a schematic flowchart showing an example of the flow of each step included in the first method. In the first method illustrated in FIG. 1, an emulsion destruction step (step S20) is performed after the aggregation step (step S10). However, as will be described later, the execution order of the aggregation step (step S10) and the emulsion destruction step (step S20) does not necessarily have to be as illustrated in FIG. 1, and the aggregation step (step S10) may be performed after the emulsion destruction step (step S20). Also, as will be described later, regarding the aggregation step (step S10), the emulsion destruction step (step S20), and the adsorption step (step S30), basically, they are the same as these steps included in the purification method of emulsion-containing oily wastewater according to the prior art (hereinafter, may be referred to as the "conventional method").

[0021] The oil droplets in water type emulsion is not particularly limited, and the first method can be applied to emulsions having various compositions and / or uses. The oil droplets in water type emulsion to which the first method is applied may contain, for example, a surfactant as an emulsifier (for example, an ionic surfactant and a non-ionic surfactant), or may not contain a surfactant. Also, the oil droplets in water type emulsion to which the first method is applied may be, for example, a lubricating oil agent, a cutting oil agent, and / or one used as the pressurized fluid described above.

[0022] The separated oil is, for example, an oil agent that is not a component of the oil droplets in water type emulsion, such as a lubricating oil agent and / or a cutting oil agent mixed into the oil droplets in water type emulsion at a processing site where plastic processing such as hydroforming and / or cutting processing is performed. The separated oil exists in the emulsion-containing oily wastewater in a separated state from the oil droplets in water type emulsion, for example, as a separation layer and / or relatively large droplets. The emulsion-containing oily wastewater may further contain foreign matters such as sludge in addition to the oil droplets in water type emulsion and the separated oil.

[0023] The coagulation step (step S10) is a step of adding a coagulant to the emulsified oily wastewater to coagulate and remove the separated oil. The coagulant used in the coagulation step (step S10) can be appropriately selected from the coagulants widely used in the technical field according to the composition and / or properties of the oil agent constituting the separated oil (and foreign matters such as sludge if the emulsified oily wastewater contains foreign matters).

[0024] Examples of the organic coagulant include alginates such as sodium alginate, polyamines, polydicyandiamides, cationized starch, cationized poly(meth)acrylamide, water-soluble aniline resins, polythiourea, polyethyleneimine, quaternary ammonium salts, polyvinylpyridines, cationic polymer coagulants such as chitosan, and the like.

[0025] Examples of the organic coagulants other than those described above include acrylic copolymers which are copolymers of hydrophilic monomers such as (meth)acrylic acid and / or (meth)acrylamide, sodium salt of carboxymethyl cellulose, maleic acid copolymer, poly(meth)acrylamide, sodium lignin sulfonate, polyoxyethylene dipropylamine, polyoxyethylene lauryl ether, surfactants such as polyoxyethylene octylphenyl ether, anionic or nonionic polymer coagulants such as copolymers of (meth)acrylic acid and acrylamide, amphoteric polymer coagulants, low molecular amine coagulants such as propylenediamine, and the like. In the present specification, the term “(meth)acrylic” shall be a general term for “acrylic” and “methacrylic”.

[0026] Examples of the ionic minerals used as inorganic coagulants include clay minerals such as bentonite, montmorillonite, kaolin, and zeolite, and aluminum sulfate, polyaluminum chloride, magnesium chloride, ferric chloride, ferrous sulfate, ferric sulfate, slaked lime, sodium silicate, sodium aluminate, aluminum alum, and the like.

[0027] In the flocculation step (step S10), one or a combination of two or more of the various flocculants as described above can be used as the flocculant. Also, in the flocculation step, in addition to the flocculant, a so-called "flocculation accelerator" may be used in combination. The flocculation accelerator can also be appropriately selected from the flocculation accelerators widely used in the art according to the composition and / or properties, etc. of the oil agent constituting the separated oil (and foreign substances such as sludge when the emulsified oily wastewater contains foreign substances) and the chemical agent used as the flocculant. As such a flocculation accelerator, for example, those other than the chemical agent selected as the flocculant from among the various flocculants as described above can be selected and used. Alternatively, a flocculation accelerator other than the chemical agents listed above can be used as the flocculant.

[0028] The separated oil flocculated as described above (and foreign substances when the emulsified oily wastewater contains foreign substances such as sludge) floats above the emulsified oily wastewater or sinks below the emulsified oily wastewater, so it can be easily removed from the emulsified oily wastewater. Incidentally, whether the flocculated separated oil (and foreign substances) floats above or sinks below the emulsified oily wastewater is determined by the magnitude relationship between the density of the oil droplets in the water in the emulsified oily wastewater and the density of the flocculated separated oil (and foreign substances).

[0029] Also, the method for removing the flocculated separated oil (and foreign substances) from the emulsified oily wastewater can be appropriately selected according to whether the flocculated separated oil (and foreign substances) floats above or sinks below the emulsified oily wastewater, etc. When the flocculated separated oil (and foreign substances) floats above the emulsified oily wastewater, for example, the emulsified oily wastewater can be extracted from below the container in which the emulsified oily wastewater is contained in the flocculation step. On the other hand, when the flocculated separated oil (and foreign substances) sinks below the emulsified oily wastewater, the emulsified oily wastewater can be extracted from above the container in which the emulsified oily wastewater is contained in the flocculation step. Furthermore, depending on the amount, composition and / or properties of the flocculated separated oil (and foreign substances), the flocculated separated oil (and foreign substances) may be removed by filtration.

[0030] The emulsion breaking step (step S20) is a step of adding an oil-water separator to the emulsified oily wastewater to break the emulsion. As is well known to those skilled in the art, the so-called "emulsion breaking" (which may be referred to as "emulsion collapse") is a phenomenon in which an emulsion, which is a dispersion system solution composed of a dispersed phase and a dispersion medium that are both liquids, can no longer be maintained. This emulsion breaking may occur at least partially along with the aggregation and removal of the separated oil (and foreign substances) due to the addition of the flocculant in the flocculation step (step S10). However, as described above, in the hydroforming process, since a high pressure is applied to the emulsion used as the pressurized fluid, the oil droplets constituting the emulsion are further refined, and the emulsion breaking tends to be more difficult.

[0031] Therefore, in the first method, the emulsion breaking is surely carried out by the emulsion breaking step (step S20) of adding an oil-water separator to the emulsified oily wastewater to break the emulsion. The oil-water separator is also referred to as an "emulsion breaker". Specific examples of the oil-water separator include, for example, inorganic compounds such as acids (e.g., hydrochloric acid or sulfuric acid, etc.), alkalis (e.g., sodium hydroxide or sodium hypochlorite, etc.), and salts, as well as organic compounds such as surfactants, phenol derivatives, and polycations. The oil-water separator preferably used in the emulsion breaking step (step S20) can be appropriately selected according to the composition and / or properties of the oil-in-water type emulsion contained in the emulsified oily wastewater.

[0032] When an anionic surfactant is used as an emulsifier, for example, a polyvalent metal salt cationic surfactant or a polycation can be added as an oil-water separator to the emulsified oily wastewater to insolubilize the anionic surfactant, thereby causing emulsion breaking. Alternatively, when a nonionic surfactant such as ethylene oxide is used as an emulsifier, for example, a phenol derivative can be added as an oil-water separator to the emulsified oily wastewater to insolubilize the surfactant, thereby causing emulsion breaking. Alternatively, when no surfactant is used as an emulsifier, for example, a mineral acid such as sulfuric acid or an alkali such as sodium hypochlorite can be added as an oil-water separator to bias the pH of the emulsified oily wastewater to acidic or alkaline, thereby causing emulsion breaking.

[0033] The emulsion breaking step (step S20) may be executed after the above-described coagulation step (step S10), or may be executed before the coagulation step (step S10). In the former case, the oil-water separator can be appropriately selected according to the composition and / or properties of the water-in-oil type emulsion contained in the emulsified oily wastewater. On the other hand, in the latter case, since the emulsified oily wastewater subjected to the emulsion breaking step contains separated oil (and foreign matters such as sludge if the emulsified oily wastewater contains foreign matters), the oil-water separator can be appropriately selected according to the composition and / or properties of not only the water-in-oil type emulsion but also the oil agent constituting the separated oil (and foreign matters if the emulsified oily wastewater contains foreign matters such as sludge).

[0034] Also, in the latter case, since the oil newly separated from the emulsion by emulsion destruction and the separated oil, which was not originally part of the emulsion, can be aggregated together, the aggregation effect is enhanced. However, since the aggregation step (step S10) has not been passed through, the emulsified oily wastewater containing the separated oil (and foreign matter) often remains turbid, making it difficult to visually confirm the effect of emulsion destruction. In addition, the emulsified oily wastewater that has not undergone the aggregation step (step S10) contains separated oil (and foreign matter) in addition to the oil droplets that make up the emulsion. Therefore, compared to the emulsified oily wastewater that has undergone the aggregation step (step S10), it is necessary to add a larger amount of oil-water separating agent. Thus, depending on the content rate of the separated oil (and foreign matter) contained in the emulsified oily wastewater, it may be desirable to perform the emulsion destruction step (step S20) after performing the aggregation step (step S10).

[0035] Furthermore, in the emulsion destruction step (step S20), in addition to adding the oil-water separating agent, emulsion destruction may be promoted by heating the emulsified oily wastewater. For example, when sulfuric acid is used as the oil-water separating agent, emulsion destruction can be promoted by heating the emulsified oily wastewater to approximately 100°C.

[0036] The adsorption step (step S30) is a step of adsorbing and removing the oil separated by emulsion destruction onto activated carbon by bringing the emulsified oily wastewater that has undergone the aggregation step (step S10) and the emulsion destruction step (step S20) into contact with the activated carbon. The activated carbon used in the adsorption step (step S30) is not particularly limited as long as it can effectively adsorb the oil separated by emulsion destruction, and can be appropriately selected from a wide variety of activated carbons widely used in wastewater treatment applications and the like in the relevant technical field. The form of the activated carbon is also not particularly limited. For example, from among activated carbons having various forms such as powdered activated carbon, granular activated carbon, and granulated activated carbon, one suitable for the equipment implementing the first method can be appropriately selected.

[0037] In the adsorption step (step S30), for example, the emulsion-containing oily wastewater that has undergone the aggregation step (step S10) and the emulsion-breaking step (step S20) is passed through a container (such as a column etc.) filled or packed with activated carbon as described above, and the wastewater is brought into contact with the activated carbon, so that the oil separated by emulsion breaking is adsorbed and removed by the activated carbon. Incidentally, in the adsorption step (step S30), not only the adsorption by the activated carbon but also the filtration by the activated carbon can remove the oil separated by emulsion breaking (and foreign matters such as sludge if the emulsion-containing oily wastewater contains foreign matters).

[0038] Regarding the aggregation step (step S10), the emulsion-breaking step (step S20), and the adsorption step (step S30) described above, as described above, basically, they are the same as these steps included in the method for purifying emulsion-containing oily wastewater according to the prior art (conventional method).

[0039] The reverse osmosis step (step S40) is a step of removing impurities by passing the emulsion-containing oily wastewater that has undergone the adsorption step (step S30) through a reverse osmosis membrane. The reverse osmosis membrane used in the reverse osmosis step (step S40) is not particularly limited as long as it can remove impurities by reverse osmosis. Specific examples of the reverse osmosis membrane include, for example, a hollow fiber membrane or a spiral membrane formed of a polymer material such as cellulose acetate or aromatic polyamide. As is well known to those skilled in the art, by applying a predetermined pressure (exceeding the osmotic pressure) to the emulsion-containing oily wastewater contained on one side of such a reverse osmosis membrane and allowing it to permeate to the other side of the reverse osmosis membrane, the impurities remaining in the emulsion-containing oily wastewater that has undergone the adsorption step can be removed.

[0040] Incidentally, the magnitude of the pressure applied to the emulsion-containing oily wastewater in the reverse osmosis step (step S40) can be appropriately determined according to, for example, the composition and / or properties of the emulsion-containing oily wastewater that has undergone the adsorption step (step S30) and / or the configuration and / or material of the reverse osmosis membrane.

[0041] Further, after at least a part of each step included in the first method is executed, a step of confirming the purification effect by the execution of each step based on a predetermined index (for example, turbidity, transparency, degree of coloring, etc.) may be provided. Further, after the execution of the reverse osmosis step, a step of confirming the purity of the water recovered through the reverse osmosis step (hereinafter, may be referred to as "recovered water") using a predetermined measuring instrument (for example, a water purity meter and / or a conductivity meter, etc.) may be provided.

[0042] <Effect> As described above, in the first method, emulsified oily wastewater containing water-in-oil type emulsions and separated oil not constituting the emulsion is subjected to coagulation removal of the separated oil and emulsion breaking, and then contacted with activated carbon and passed through a reverse osmosis membrane. As a result, according to the first method, water purified to a higher level than before can be recovered.

[0043] <<Second Embodiment>> Hereinafter, a method for purifying emulsified oily wastewater according to the second embodiment of the present invention (hereinafter, may be referred to as "second method") will be described with reference to the drawings.

[0044] As described above, in the emulsion breaking step, an acid (for example, hydrochloric acid or sulfuric acid, etc.) or an alkali (for example, sodium hydroxide or sodium hypochlorite, etc.) may be added as an oil-water separating agent to bias the pH of the emulsified oily wastewater to acidic or alkaline. Also, depending on the use of the water-in-oil type emulsion, for example, due to the mixing of an acid or an alkali in the use environment, the pH of the emulsified oily wastewater may be biased to acidic or alkaline.

[0045] The emulsified oily wastewater with a pH biased to acidic or alkaline as described above may damage the members constituting the equipment in which each step included in the purification method is executed. Specifically, for example, when the pH of the emulsified oily wastewater is biased to acidic or alkaline, the activated carbon used in the adsorption step may be damaged.

[0046] <Composition> Therefore, the second method is the above-described first method, and is a method for purifying emulsified oily wastewater that further includes a neutralization step between the emulsion destruction step and the adsorption step. The neutralization step is a step of adding a neutralizing agent to the emulsified oily wastewater that has undergone the emulsion destruction step at a point in time after the emulsion destruction step and before the adsorption step, to bring the pH of the emulsified oily wastewater closer to neutral.

[0047] The neutralizing agent used in the neutralization step is not particularly limited as long as it can bring the pH of the emulsified oily wastewater that has undergone the emulsion destruction step closer to neutral and does not adversely affect the purification effect of the emulsified oily wastewater by the second method. When the pH of the emulsified oily wastewater subjected to the neutralization step is biased towards acidity, for example, by adding an alkali such as sodium hydroxide or sodium hypochlorite as a neutralizing agent, the pH of the emulsified oily wastewater can be brought closer to neutral. On the other hand, when the pH of the emulsified oily wastewater subjected to the neutralization step is biased towards alkalinity, for example, by adding an acid such as hydrochloric acid or sulfuric acid as a neutralizing agent, the pH of the emulsified oily wastewater can be brought closer to neutral.

[0048] Figure 2 is a schematic flowchart showing an example of the flow of each step included in the second method, and is different from the flowchart of the first method illustrated in Figure 1 only in that a neutralization step (step S25) is included between the emulsion destruction step (step S20) and the next adsorption step (step S30).

[0049] In the second method illustrated in FIG. 2, an emulsion breaking step (step S20) is executed after the aggregation step (step S10), and a neutralization step (step S25) is executed between the emulsion breaking step (step S20) and the next adsorption step (step S30). However, as described in the explanation of the first method, the execution order of the aggregation step (step S10) and the emulsion breaking step (step S20) does not necessarily have to be as illustrated in FIGS. 1 and 2, and the aggregation step (step S10) may be executed after the emulsion breaking step (step S20).

[0050] When the aggregation step (step S10) is executed after the emulsion breaking step (step S20), the neutralization step (step S25) can be executed between the emulsion breaking step (step S20) and the aggregation step (step S10) or between the aggregation step (step S10) and the adsorption step (step S30). However, when there is a concern about adverse effects such as a decrease in the aggregation effect in the aggregation step (step S10) if the pH of the emulsified oily wastewater subjected to the aggregation step (step S10) is biased towards acidity or alkalinity, it is desirable to execute the neutralization step (step S25) between the emulsion breaking step (step S20) and the aggregation step (step S10).

[0051] <Effect> As described above, in the second method, at a point in time after the emulsion breaking step and before the adsorption step, a neutralization step is executed in which a neutralizing agent is added to the emulsified oily wastewater that has undergone the emulsion breaking step to bring the pH of the emulsified oily wastewater closer to neutral. As a result, according to the second method, it is possible to reduce the possibility that the activated carbon used in the adsorption step is damaged due to the deviation of the pH of the emulsified oily wastewater.

[0052] <<Third Embodiment>> Hereinafter, a method for purifying emulsified oily wastewater according to the third embodiment of the present invention (hereinafter, may be referred to as the "third method") will be described with reference to the drawings.

[0053] As described above, in the method for purifying emulsion-containing oily wastewater according to various embodiments of the present invention including the first method and the second method (the method of the present invention), the emulsion-containing oily wastewater containing water-in-oil droplets and separated oil not constituting the emulsion is subjected to coagulation removal of the separated oil and emulsion breaking, and then contacted with activated carbon and passed through a reverse osmosis membrane. As is well known to those skilled in the art, according to the reverse osmosis process, impurities larger than water molecules can be effectively removed. Therefore, according to the method of the present invention, water purified to a higher level than before can be recovered.

[0054] When it is required to recover water with higher purity, it is desirable to subject the water recovered through the reverse osmosis process (recovered water) to ion exchange treatment with a resin having ion exchange ability (ion exchange resin) to remove trace ions that may be contained in the recovered water.

[0055] <Configuration> Therefore, the third method is a method for purifying emulsion-containing oily wastewater, which is the first method or the second method described above and further includes an ion exchange step after the reverse osmosis step. The ion exchange step is a step of removing ionic impurities contained in the emulsion-containing oily wastewater by bringing the emulsion-containing oily wastewater that has undergone the reverse osmosis step into contact with an ion exchange resin.

[0056] The ion exchange resin used in the ion exchange step is not particularly limited as long as it can adsorb trace ions (counter ions) that may be contained in the recovered water by an ion exchange action. Specifically, as is well known to those skilled in the art, an ion exchange resin having an ion exchange group that can selectively adsorb counter ions to be removed by adsorption (for example, sodium ions and / or chloride ions, etc.) is selected. The form of the ion exchange resin is also not particularly limited, and for example, from among ion exchange resins having various forms such as granular, fibrous, and membranous, one suitable for the equipment for implementing the third method can be appropriately selected.

[0057] FIG. 3 is a schematic flowchart showing an example of the flow of each step included in the third method, and is different from the flowchart of the second method illustrated in FIG. 2 only in that an ion exchange step (step S50) is included after the reverse osmosis step (step S40). The execution order of the coagulation step (step S10), the emulsion breaking step (step S20), and the neutralization step (step S25) is as described in the description of the second method.

[0058] <Effect> As described above, in the third method, after the reverse osmosis step, an ion exchange step is performed in which the emulsified oily wastewater that has undergone the reverse osmosis step is brought into contact with an ion exchange resin to remove ionic impurities contained in the emulsified oily wastewater. As a result, according to the third method, even trace amounts of ions that may be contained in the recovered water can be removed, and water with a higher purity (hereinafter, may be referred to as "purified water") can be obtained.

[0059] <<Fourth Embodiment>> As described at the beginning of this specification, the present invention relates not only to a method for purifying emulsified oily wastewater but also to a device for purifying emulsified oily wastewater. The device for purifying emulsified oily wastewater according to the present invention (the device of the present invention) is a device configured to implement a method for purifying emulsified oily wastewater (the method of the present invention) according to various embodiments including the above-described first to third methods. Hereinafter, a device for purifying emulsified oily wastewater according to the fourth embodiment of the present invention (hereinafter, may be referred to as the "first device") will be described with reference to the drawings.

[0060] <Configuration> The first device is a device for purifying emulsified oily wastewater that recovers water from emulsified oily wastewater containing an oil-in-water type emulsion and separated oil that is not an emulsion. The first device is a device for purifying emulsified oily wastewater having a coagulation unit, an emulsion breaking unit, an adsorption unit, and a reverse osmosis unit.

[0061] FIG. 4 is a schematic block diagram showing an example of the configuration of the first device. The first device 101 illustrated in FIG. 4 includes a coagulation unit 10, an emulsion destruction unit 20, an adsorption unit 30, and a reverse osmosis unit 40.

[0062] The coagulation unit 10 includes a coagulation tank 11 that is a container for storing emulsified oily wastewater, and a coagulant addition means 12 configured to add a coagulant to the emulsified oily wastewater stored in the coagulation tank 11. Further, the coagulation unit 10 illustrated in FIG. 4 also includes a coagulation accelerator addition means 13 configured to add a coagulation accelerator to the emulsified oily wastewater stored in the coagulation tank 11. The configurations of the coagulant addition means 12 and the coagulation accelerator addition means 13 can be appropriately determined according to the composition and / or properties of the chemicals added as the coagulant and the coagulation accelerator. In addition, the coagulation unit 10 illustrated in FIG. 4 includes stirring means driven by a motor M1 for the purpose of promoting the mixing of the emulsified oily wastewater in the coagulation tank 11 with the coagulant and the coagulation accelerator. However, stirring means such as a bubble stirring unit that promotes stirring by minute bubbles of a gas such as nitrogen or air may also be used. However, the coagulation accelerator addition means 13 and the stirring means are not essential components of the first device 101.

[0063] The coagulation unit 10 is configured to perform a coagulation step of adding a coagulant to the emulsified oily wastewater by the coagulant addition means 12 to coagulate and remove the separated oil. Further, since the coagulation unit 10 illustrated in FIG. 4 includes the coagulation accelerator addition means 13 and the stirring means as described above, the coagulation of the separated oil is promoted by these, and the separated oil can be effectively removed. Note that the details of the coagulation step have already been described in the description of the method for purifying emulsified oily wastewater (first method) according to the first embodiment of the present invention, and thus the description here is omitted.

[0064] In the agglomeration section 10 illustrated in Fig. 4, it is assumed that the agglomerated separated oil (and foreign matter) floats above the emulsified oily wastewater. The emulsified oily wastewater from which the separated oil (and foreign matter) has been removed by the agglomeration process is discharged from below the agglomeration tank 11 and supplied to the next emulsion breaking section 20. However, as described above, the method for removing the agglomerated separated oil (and foreign matter) from the emulsified oily wastewater can be appropriately selected according to whether the agglomerated separated oil (and foreign matter) floats above or sinks below the emulsified oily wastewater, etc.

[0065] The emulsion breaking section 20 includes an emulsion breaking tank 21 which is a container for accommodating the emulsified oily wastewater, and an oil-water separating agent adding means 22 configured to add an oil-water separating agent to the emulsified oily wastewater accommodated in the emulsion breaking tank. The configuration of the oil-water separating agent adding means 22 can be appropriately determined according to the composition and / or properties of the chemical agent added as the oil-water separating agent, etc. In addition, the emulsion breaking section 20 illustrated in Fig. 4 includes a stirring means driven by a motor M2 for the purpose of promoting the mixing of the emulsified oily wastewater and the oil-water separating agent in the emulsion breaking tank 21. However, for example, a stirring means such as a bubble stirring unit that promotes stirring by minute bubbles of a gas such as nitrogen or air may be used. However, such a stirring means is not an essential component of the first device 101.

[0066] The emulsion breaking section 20 is configured to execute an emulsion breaking process in which an oil-water separating agent is added to the emulsified oily wastewater by the oil-water separating agent adding means 22 to break the emulsion. Since the emulsion breaking section 20 illustrated in Fig. 4 includes the stirring means as described above, emulsion breaking can be performed more effectively thereby. Incidentally, since the details of the emulsion breaking process have already been described in the description of the method for purifying emulsified oily wastewater (first method) according to the first embodiment of the present invention, the description here is omitted.

[0067] In the emulsion breaking unit 20 illustrated in FIG. 4, the emulsified oily wastewater that has undergone the emulsion breaking process is pumped out from the emulsion breaking tank 21 by the pump P1 and supplied to the next adsorption unit 30. However, the configuration for supplying the emulsified oily wastewater that has undergone the emulsion breaking process in the emulsion breaking unit 20 to the next adsorption unit 30 is not limited to the configuration including such a pump P1, and can be appropriately selected according to the amount, composition, and / or properties of the emulsified oily wastewater that has undergone the emulsion breaking process.

[0068] The adsorption unit 30 includes activated carbon (not shown) and an adsorption tank 31 that is a container for housing the activated carbon. Typically, the adsorption unit 30 is a container such as a column that has an inlet for the emulsified oily wastewater to be subjected to the adsorption process and an outlet for the emulsified oily wastewater that has undergone the adsorption process, and the activated carbon is housed or filled inside.

[0069] The adsorption unit 30 is configured to perform an adsorption process of adsorbing and removing the oil separated by emulsion breaking on the activated carbon by bringing the emulsified oily wastewater that has undergone the flocculation process and the emulsion breaking process into contact with the activated carbon. In the adsorption unit 30 illustrated in FIG. 4, the emulsified oily wastewater that has undergone the emulsion breaking process is supplied from the emulsion breaking tank 21 to the adsorption unit 30 by the pump P1 and comes into contact with the activated carbon in the process of flowing through the inside of the adsorption tank 31. Thereby, the oil separated by emulsion breaking can be adsorbed on the activated carbon and removed from the emulsified oily wastewater. Note that the details of the adsorption process have already been described in the description of the method for purifying emulsified oily wastewater (first method) according to the first embodiment of the present invention, and thus the description here is omitted.

[0070] Incidentally, as described in the explanation of the first method, after at least a part of each step is executed, a step of confirming the purification effect by the execution of each step based on a predetermined index (for example, turbidity, transparency, and / or degree of coloring, etc.) may be provided. Therefore, in the first apparatus 101 illustrated in FIG. 4, for the purpose of confirming the purification effect by the execution of the adsorption step, an adsorption effect confirmation unit 30' is provided on the downstream side of the adsorption unit 30. The adsorption effect confirmation unit 30' includes an adsorption effect confirmation tank 31' which is a container for accommodating the emulsified oily wastewater discharged from the adsorption tank 31, and a pump P2 for pumping out the emulsified oily wastewater from the adsorption effect confirmation tank 31' and supplying it to the next reverse osmosis unit 40. In the adsorption effect confirmation unit 30', the purification effect by the execution of the adsorption step is confirmed based on the turbidity, transparency, and / or degree of coloring, etc. of the emulsified oily wastewater accommodated in the adsorption effect confirmation tank 31'.

[0071] In addition, when it is determined that the purification effect by the execution of the adsorption step is insufficient in the adsorption effect confirmation unit 30', the emulsified oily wastewater may be returned from the adsorption effect confirmation unit 30' to the adsorption unit 30 and circulated. In this case, the adsorption effect confirmation unit 30' includes means (for example, a pump, etc.) for returning the emulsified oily wastewater from the adsorption effect confirmation tank 31' to the adsorption tank 31 (refer to the two-dot chain line arrow R1 shown in the figure). This means may be dedicated means provided only for the purpose of returning the emulsified oily wastewater from the adsorption effect confirmation tank 31' to the adsorption tank 31. Alternatively, this means may be shared means in which the same means (for example, the pump P1 disposed in the emulsion breaking tank 21, etc.) provided in other components constituting the first apparatus 101 is transferred to the adsorption effect confirmation tank 31'. However, the adsorption effect confirmation unit 30' is not an essential component of the first apparatus 101. When the first apparatus 101 does not include the adsorption effect confirmation unit 30', the emulsified oily wastewater may be directly returned from the downstream side to the upstream side of the adsorption tank 31 without passing through the adsorption effect confirmation unit 30'.

[0072] The reverse osmosis unit 40 includes a reverse osmosis tank 41 which is a container whose internal space is partitioned by a reverse osmosis membrane (not shown), and a pressurizing means (not shown) configured to apply pressure to the emulsified oily wastewater that has undergone the adsorption process and is accommodated on one side of the reverse osmosis membrane of the reverse osmosis tank. Incidentally, the pressurizing means included in the reverse osmosis unit 40 may be constituted by the pump P2 included in the adsorption effect confirmation unit 30'.

[0073] The reverse osmosis unit 40 is configured to perform a reverse osmosis process of removing impurities by passing the emulsified oily wastewater through the reverse osmosis membrane by applying pressure to the emulsified oily wastewater by the pressurizing means. Thereby, the impurities remaining in the emulsified oily wastewater that has undergone the adsorption process can be removed. Incidentally, since the details of the reverse osmosis process have already been described in the explanation regarding the method for purifying emulsified oily wastewater (first method) according to the first embodiment of the present invention, the explanation here is omitted.

[0074] In the first apparatus 101 illustrated in FIG. 4, a water storage unit 60 for storing the water (recovered water) discharged from the reverse osmosis unit 40 through the reverse osmosis process is provided on the downstream side of the reverse osmosis unit 40. The water storage unit 60 includes a recovered water tank 61 which is a container for accommodating the recovered water. However, the water storage unit 60 is not an essential component of the first apparatus 101.

[0075] By the way, as is well known to those skilled in the art, in the reverse osmosis unit 40, the concentrated water in which the impurities that could not pass through the reverse osmosis membrane are concentrated is continuously discharged. This concentrated water is generally discharged from the reverse osmosis unit 40 through a path such as a waste pipe (not shown) and discarded. However, from the viewpoint of reducing the amount of concentrated water to be discarded, it is desirable to return the concentrated water to the upstream side of the reverse osmosis membrane of the reverse osmosis tank 41 and circulate it. In this case, the reverse osmosis unit 40 includes means for returning the concentrated water discharged from the reverse osmosis tank 41 to the upstream side (for example, the adsorption effect confirmation tank 31') of the reverse osmosis membrane of the reverse osmosis tank 41 (see the two-dot chain line arrow R2 shown in the figure). This means may be, for example, a flow path for returning the concentrated water by the pressure applied to the emulsified oily wastewater by the pressurizing means, or a flow path provided with a pump or the like for actively returning the concentrated water.

[0076] Incidentally, as described in the explanation of the first method, the execution order of the aggregation step (step S10) and the emulsion destruction step (step S20) does not necessarily have to be as illustrated in FIG. 1, and the aggregation step (step S10) may be executed after the emulsion destruction step (step S20). Therefore, the arrangement of the aggregation unit 10 and the emulsion destruction unit 20 in the first apparatus 101 also does not necessarily have to be as illustrated in FIG. 4, and the aggregation unit 10 may be arranged on the downstream side of the emulsion destruction unit 20. <Effect> As described above, in the first apparatus, the oil-in-water emulsion and the emulsified oily wastewater containing separated oil that does not constitute the emulsion are subjected to aggregation removal of the separated oil and emulsion destruction, and then contacted with activated carbon and then passed through a reverse osmosis membrane. As a result, according to the first apparatus, water purified to a higher level than before can be recovered.

[0077] <<Fifth Embodiment>> Hereinafter, a purification apparatus for emulsified oily wastewater according to the fifth embodiment of the present invention (hereinafter, may be referred to as the "second apparatus") will be described with reference to the drawings.

[0078] As described in the explanation of the purification method (second method) for emulsified oily wastewater according to the second embodiment of the present invention, in the emulsion destruction step, an acid (for example, hydrochloric acid or sulfuric acid, etc.) or an alkali (for example, sodium hydroxide or sodium hypochlorite, etc.) may be added as an oil-water separating agent to bias the pH of the emulsified oily wastewater to acidic or alkaline. Also, depending on the use of the oil-in-water emulsion, for example, due to the mixing of an acid or an alkali in the use environment, the pH of the emulsified oily wastewater may be biased to acidic or alkaline.

[0079] As described above, emulsion-type oily wastewater with a pH biased towards acidity or alkalinity may damage the components constituting the purification device for emulsion-type oily wastewater (the device of the present invention) according to various embodiments of the present invention, including the above-described first device. Specifically, for example, when the pH of the emulsion-type oily wastewater is biased towards acidity or alkalinity, the activated carbon provided in the adsorption section may be damaged.

[0080] 〈Configuration〉 Therefore, the second device is the above-described first device, which is a purification device for emulsion-type oily wastewater and further has a neutralization section. FIG. 5 is a schematic block diagram showing an example of the configuration of the second device. The second device 102 illustrated in FIG. 5 has a different configuration from the first device 101 illustrated in FIG. 4 in that it further has a neutralization section 25 in addition to the aggregation section 10, the emulsion destruction section 20, the adsorption section 30, and the reverse osmosis section 40.

[0081] The neutralization section 25 includes a neutralization tank 26, which is a container for storing the emulsion-type oily wastewater that has undergone the emulsion destruction process, and a neutralizing agent addition means 27 configured to add a neutralizing agent to the emulsion-type oily wastewater stored in the neutralization tank. In the second device 102 illustrated in FIG. 5, it is assumed that the emulsion-type oily wastewater that has undergone the emulsion destruction process is subjected to the neutralization process without being transferred from the emulsion destruction tank 21 to another container. Therefore, the emulsion destruction tank 21 provided in the emulsion destruction section 20 is configured to also function as the neutralization tank 26, but the emulsion destruction tank 21 and the neutralization tank 26 may be configured as separate containers. Note that the configuration of the neutralizing agent addition means 27 can be appropriately determined according to the composition and / or properties of the chemical agent added as the oil-water separator.

[0082] The neutralization unit 25 is configured to perform a neutralization process of adding a neutralizing agent to the emulsified oily wastewater by means of a neutralizing agent adding means at a point in time after the emulsion breaking process and before the adsorption process, so as to bring the pH of the emulsified oily wastewater close to neutral. That is, the neutralization unit 25 is arranged at a position downstream of the emulsion breaking unit 20 and upstream of the adsorption unit 30 from the perspective of the execution order of each process. Thereby, it is possible to reduce the possibility that the activated carbon provided in the adsorption unit 30 is damaged due to the deviation of the pH of the emulsified oily wastewater.

[0083] <Effect> As described above, in the second device, at a point in time after the emulsion breaking process and before the adsorption process, a neutralization process is performed in which a neutralizing agent is added to the emulsified oily wastewater that has undergone the emulsion breaking process to bring the pH of the emulsified oily wastewater close to neutral. As a result, according to the second device, it is possible to reduce the possibility that the activated carbon used in the adsorption process is damaged due to the deviation of the pH of the emulsified oily wastewater.

[0084] <<Sixth Embodiment>> Hereinafter, a purification device for emulsified oily wastewater according to the sixth embodiment of the present invention (hereinafter, may be referred to as the "third device") will be described with reference to the drawings.

[0085] As described above, in the purification device for emulsified oily wastewater according to various embodiments of the present invention including the first device and the second device (the present invention device), emulsified oily wastewater containing water-in-oil type emulsions and separated oil that does not constitute an emulsion is subjected to coagulation removal of the separated oil and emulsion breaking, and then passed through a reverse osmosis membrane after being brought into contact with activated carbon. As is well known to those skilled in the art, according to the reverse osmosis process, impurities larger than water molecules can be effectively removed. Therefore, according to the present invention device, it is possible to recover water purified to a higher level than before.

[0086] When it is required to recover water with a higher purity, it is desirable to subject the water (recovered water) recovered through the reverse osmosis process to ion exchange treatment with a resin having ion exchange ability (ion exchange resin) to remove even trace amounts of ions that may be contained in the recovered water.

[0087] <Configuration> Therefore, the third device is the above-described first device or second device, and further has an ion exchange section. The ion exchange section is a purification device for emulsion-containing oily wastewater, which includes an ion exchange resin and an ion exchange tank that is a container for housing the ion exchange resin.

[0088] FIG. 6 is a schematic block diagram showing an example of the configuration of the third device. The third device 103 illustrated in FIG. 6 has a different configuration from the second device 102 illustrated in FIG. 5 in that it further has an ion exchange section 50 in addition to the coagulation section 10, the emulsion destruction section 20, the neutralization section 25, the adsorption section 30, and the reverse osmosis section 40.

[0089] The ion exchange section is configured to perform an ion exchange process of removing ionic impurities contained in the emulsion-containing oily wastewater by bringing the emulsion-containing oily wastewater that has undergone the reverse osmosis process into contact with the ion exchange resin. Thereby, even trace amounts of ions that may be contained in the water (recovered water) recovered through the reverse osmosis process can be removed, and water with a higher purity (purified water) can be obtained. Note that the details of the ion exchange process have already been described in the description of the method for purifying emulsion-containing oily wastewater (third method) according to the third embodiment of the present invention, and thus the description here is omitted.

[0090] Incidentally, in the third apparatus 103 illustrated in FIG. 6, for the purpose of confirming the purification effect by performing the reverse osmosis process, a reverse osmosis effect confirmation unit 40' is provided on the downstream side of the reverse osmosis unit 40. The reverse osmosis effect confirmation unit 40' includes a reverse osmosis effect confirmation tank 41' which is a container for storing the emulsified oily wastewater discharged from the reverse osmosis tank 41, and a pump P3 for pumping out the emulsified oily wastewater from the reverse osmosis effect confirmation tank 41' and supplying it to the next ion exchange unit 50. In the reverse osmosis effect confirmation unit 40', based on the turbidity, transparency and / or degree of coloring, etc. of the emulsified oily wastewater stored in the reverse osmosis effect confirmation tank 41', the purification effect by performing the reverse osmosis process is confirmed.

[0091] Furthermore, in the third apparatus 103 illustrated in FIG. 6, a water storage unit 60 for storing the water (purified water) discharged from the ion exchange unit 50 after passing through the ion exchange process is provided on the downstream side of the ion exchange unit 50, and the water storage unit 60 includes a purified water tank 62 which is a container for storing the purified water.

[0092] In addition, in the third apparatus 103 illustrated in FIG. 6, for the purpose of confirming the purification effect by performing the ion exchange process, a pure water meter 52 is provided between the ion exchange unit 50 and the water storage unit 60. The pure water meter 52 can measure the purity of water based on, for example, electric conductivity (conductivity).

[0093] However, the reverse osmosis effect confirmation unit 40', the water storage unit 60 and the pure water meter 52 are not essential components of the third apparatus 103.

[0094] <Effect> As described above, in the third apparatus, after the reverse osmosis process, an ion exchange process is performed in which the emulsified oily wastewater that has undergone the reverse osmosis process is brought into contact with an ion exchange resin to remove ionic impurities contained in the emulsified oily wastewater. As a result, according to the third apparatus, trace ions that may be contained in the recovered water can also be removed, and water (purified water) with a higher purity can be obtained. <Example>

[0095] A purification method for emulsion-containing oily wastewater according to various embodiments of the present invention, including the first to third methods described above, and an example of a purification apparatus for emulsion-containing oily wastewater according to various embodiments of the present invention, including the first to third apparatuses, will be described below with reference to the drawings. However, the embodiments described below are merely illustrative and do not limit the scope of the present invention.

[0096] FIG. 7 is a schematic perspective view showing an example of the configuration of a purification apparatus (example apparatus) for emulsion-containing oily wastewater according to an embodiment of the present invention. The example apparatus 110 illustrated in FIG. 7 has a configuration corresponding to the purification apparatus for emulsion-containing oily wastewater (third apparatus 103) according to the sixth embodiment of the present invention described above with reference to FIG. 6. That is, the example apparatus 110 includes, in order from the upstream side in the flow of the emulsion-containing oily wastewater, a coagulation unit 10, an emulsion-breaking unit 20, a neutralization unit 25, an adsorption unit 30, an adsorption effect confirmation unit 30', a reverse osmosis unit 40, a reverse osmosis effect confirmation unit 40', an ion exchange unit 50, and a water storage unit 60.

[0097] Similar to the above-described third apparatus 103, the coagulation unit 10 includes a coagulation tank 11 and coagulant addition means and coagulation accelerator addition means (not shown), and the emulsion-breaking unit 20 includes an emulsion-breaking tank 21 and oil-water separation agent addition means (not shown). The neutralization unit 25 uses the emulsion-breaking tank 21 as a neutralization tank 26 and includes neutralizing agent addition means (not shown), the adsorption unit 30 includes an adsorption tank 31 filled with activated carbon inside, and the adsorption effect confirmation unit 30' includes an adsorption effect confirmation tank 31'. Further, the reverse osmosis unit 40 includes a reverse osmosis tank 41 whose internal space is partitioned by a reverse osmosis membrane (not shown), and the reverse osmosis effect confirmation unit 40' includes a reverse osmosis effect confirmation tank 41'. In addition, the ion exchange unit 50 includes an ion exchange tank 51 in which an ion exchange resin (not shown) is accommodated and a conductivity-type pure water meter 52, and the water storage unit 60 includes a purified water tank 62.

[0098] In the flocculation step performed in the flocculation unit 10, commercially available inorganic flocculants and flocculation accelerators were used. In the emulsion breaking step performed in the emulsion breaking unit 20, sodium hypochlorite was used as an oil-water separator, and in the neutralization step performed in the neutralization unit 25, hydrochloric acid was used as a neutralizing agent. Further, a pump P1 for supplying the emulsified oily wastewater that has undergone the emulsion breaking step and the neutralization step to the next adsorption unit 30 is provided in the emulsion breaking tank 21 also serving as the neutralization tank 26, a pump P2 for supplying the emulsified oily wastewater that has undergone the adsorption step to the next reverse osmosis unit 40 is provided in the adsorption effect confirmation tank 31', and a pump P3 for supplying the emulsified oily wastewater that has undergone the reverse osmosis step to the next ion exchange unit 50 is provided in the reverse osmosis effect confirmation tank 41'.

[0099] With the example apparatus 110 having the above-described configuration, purified water was recovered from emulsified oily wastewater mainly composed of an oil-in-water droplet type emulsion (HYSOL X, manufactured by CASTROL LIMITED) used as a pressurized fluid in hydroforming. Incidentally, machine oil used in hydroforming was mixed in the emulsified oily wastewater, forming a layer separated from the above emulsion. That is, this machine oil corresponds to the separated oil described above.

[0100] As a result of purifying the above-described emulsified oily wastewater with the example apparatus 110, extremely clean water at the pure water level could be recovered. That is, according to the present invention, emulsified oily wastewater can be purified to a higher level than before. Therefore, it was confirmed that according to the present invention, excellent effects such as reduction of environmental load, conservation of water resources, and reduction of costs in applications where emulsified oily wastewater is discharged (for example, plastic processing, etc.) can be achieved.

[0101] For the purpose of describing the present invention above, several embodiments and examples with specific configurations have been described with reference to the accompanying drawings at times. However, the scope of the present invention should not be construed as being limited to these exemplary embodiments and examples, and it goes without saying that appropriate modifications can be made within the scope of the matters described in the claims and the specification.

Explanation of Signs

[0102] 101, 102, 103, 110... Purification devices for emulsified oily wastewater 10... Coagulation section 11... Coagulation tank 12... Coagulant addition means 13... Coagulation accelerator addition means 20... Emulsion breaking section 21... Emulsion breaking tank 22... Oil-water separator addition means 25... Neutralization section 26... Neutralization tank 27... Neutralizing agent addition means 30... Adsorption section 31... Adsorption tank 30’... Adsorption effect confirmation section 31’... Adsorption effect confirmation tank 40... Reverse osmosis section 41... Reverse osmosis tank 40’... Reverse osmosis effect confirmation section 41’... Reverse osmosis effect confirmation tank 50... Ion exchange section 51... Ion exchange tank 52... Pure water meter 60... Water storage section 61... Recovered water tank 62... Purified water tank

Claims

1. A method for purifying emulsified oily wastewater for recovering water from emulsified oily wastewater containing an oil-in-water emulsion and separated oil which is oil not constituting the emulsion, comprising: a flocculation step of adding a flocculant to the emulsified oily wastewater to flocculate and remove the separated oil; an emulsion breaking step of adding an oil-water separator to the emulsified oily wastewater that has undergone the flocculation step to break the emulsion; an adsorption step of contacting the emulsified oily wastewater that has undergone the emulsion breaking step with activated carbon to adsorb and remove the oil separated by the emulsion breaking onto the activated carbon; a reverse osmosis step of passing the emulsified oily wastewater that has undergone the adsorption step through a reverse osmosis membrane to remove impurities; including A method for purifying emulsified oily wastewater.

2. The method for purifying emulsified oily wastewater according to claim 1, further comprising a neutralization step of adding a neutralizing agent to the emulsified oily wastewater that has undergone the emulsion breaking step at a point after the emulsion breaking step and before the adsorption step to bring the pH of the emulsified oily wastewater closer to neutral. A method for purifying emulsified oily wastewater.

3. The method for purifying emulsified oily wastewater according to claim 1 or claim 2, further comprising an ion exchange step of contacting the emulsified oily wastewater that has undergone the reverse osmosis step with an ion exchange resin to remove ionic impurities contained in the emulsified oily wastewater. A method for purifying emulsified oily wastewater.

4. An apparatus for purifying emulsified oily wastewater for recovering water from emulsified oily wastewater containing an oil-in-water emulsion and separated oil which is oil not constituting the emulsion, comprising: A flocculation tank which is a container for containing the emulsion-containing oily wastewater, and a flocculant addition means configured to add a flocculant to the emulsion-containing oily wastewater contained in the flocculation tank, and a flocculation section configured to execute a flocculation step of adding the flocculant to the emulsion-containing oily wastewater by the flocculant addition means to flocculate and remove the separated oil. An emulsion-breaking tank which is a container for containing the emulsion-containing oily wastewater, and an oil-water separation agent addition means configured to add an oil-water separation agent to the emulsion-containing oily wastewater contained in the emulsion-breaking tank, and an emulsion-breaking section configured to execute an emulsion-breaking step of adding the oil-water separation agent to the emulsion-containing oily wastewater by the oil-water separation agent addition means to break the emulsion. An adsorption section comprising activated carbon and an adsorption tank which is a container for containing the activated carbon, and configured to execute an adsorption step of adsorbing and removing the oil separated by emulsion breaking by bringing the emulsion-containing oily wastewater that has undergone the flocculation step and the emulsion-breaking step into contact with the activated carbon. A reverse osmosis tank which is a container whose internal space is partitioned by a reverse osmosis membrane, and a pressurizing means configured to apply pressure to the emulsion-containing oily wastewater that has undergone the adsorption step and is contained on one side of the reverse osmosis membrane of the reverse osmosis tank, and a reverse osmosis section configured to execute a reverse osmosis step of removing impurities by passing the emulsion-containing oily wastewater through the reverse osmosis membrane by pressurizing the emulsion-containing oily wastewater by the pressurizing means. having configured to execute the emulsion-breaking step after the flocculation step. A purification device for emulsion-containing oily wastewater.

5. The purification device for emulsion-containing oily wastewater according to claim 4, A neutralization tank which is a container for containing the emulsion-containing oily wastewater that has undergone the emulsion destruction process, and neutralizing agent addition means configured to add a neutralizing agent to the emulsion-containing oily wastewater contained in the neutralization tank. A neutralization section is further provided which is configured to perform a neutralization process of adding the neutralizing agent to the emulsion-containing oily wastewater by the neutralizing agent addition means at a time point after the emulsion destruction process and before the adsorption process to bring the pH of the emulsion-containing oily wastewater closer to neutrality. A purification device for emulsion-containing oily wastewater.

6. A purification device for emulsion-containing oily wastewater according to claim 4 or claim 5, Comprising an ion exchange resin and an ion exchange tank which is a container for containing the ion exchange resin, and further having an ion exchange section configured to perform an ion exchange process of removing ionic impurities contained in the emulsion-containing oily wastewater by bringing the emulsion-containing oily wastewater that has undergone the reverse osmosis process into contact with the ion exchange resin. A purification device for emulsion-containing oily wastewater.

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