JP6414470B2 - Water treatment equipment - Google Patents

Description

  The present invention relates to a water treatment apparatus that purifies water by removing an adsorbed substance from water containing the adsorbed substance, and in particular, industrial wastewater containing the adsorbed substance discharged from various factories or research facilities. Further, the present invention relates to a water treatment apparatus that purifies the treated water by efficiently removing adsorbed substances using leachate and groundwater discharged from the final disposal site as treated water.

  Conventionally, adsorption / desorption in which the water to be treated is brought into contact with the adsorbent and the adsorbed material is adsorbed and removed and the desorption process in which the heated gas is brought into contact with the adsorbent and the adsorbed material is desorbed from the adsorbent are alternately performed. A water treatment apparatus that operates is being studied (for example, Patent Document 1). This water treatment apparatus basically does not require replacement of the adsorbent, and can remove the adsorbed substance stably with high efficiency.

  Activated carbon fibers are known as adsorbents to be used. Since the activated carbon fiber has a high adsorption rate and a large micropore volume, it is generally known that it can remove an adsorbed substance such as an organic solvent with a small amount of adsorbent material with high efficiency. Moreover, as heating gas, the heating air and water vapor | steam of about 140 degreeC are used from a viewpoint of economical efficiency or the heat-resistant temperature of an adsorbent.

  As described above, when utilizing the characteristics of the water treatment device by the adsorbent and the heating gas temperature to be used, the target substance for adsorption removal from the treated water is a low boiling point, low molecular weight adsorbed substance typified by an organic solvent. Become. For example, wastewater treatment containing organic solvent discharged from organic solvent recovery equipment, wastewater treatment such as isopropyl alcohol discharged from semiconductor factories, etc., removal of 1,4-dioxane contained in industrial wastewater, leachate and groundwater, groundwater, Examples include removal of trichlorethylene contained in well water and clean water.

  However, in most cases, the actual treated water contains various adsorbed substances. For example, difficult-to-desorb substances coexist in the water to be treated, and when these substances are adsorbed or adhered to the adsorbent, the heated gas at the above temperature is difficult to desorb from the adsorbent, so it remains in the pores and reduces the adsorption capacity. (So-called deterioration), and there is a problem that the frequency of replacement of the adsorbent increases.

  The hard-to-desorb substances described here have a boiling point of 140 ° C. or higher, such as organic polymers, organic oligomers, proteins, saccharides, fatty acids, fatty acid esters, amines, amide compounds, fats and oils, resins, surfactants, high-boiling solvents, etc. Examples include inorganic substances such as organic substances, sulfates, sulfides, and iron rust.

  In the case of treating the water to be treated containing such a difficult-to-desorb substance, there is a measure to perform the adsorption / desorption operation by raising the temperature of the heated gas, but there is a problem of increasing the running cost for raising the temperature of the heated gas. . There is also a measure to prolong the life of the adsorbent by adding a pretreatment device that can be effectively removed in advance according to the physical properties and concentration of the hard-to-desorb substance, and avoiding the temperature rise of the heated gas. It is difficult to remove, and a small amount of hard-to-desorb substances that have not been removed in advance by pretreatment gradually accumulates and remains in the adsorbent depending on the operating time, and deteriorates. Some cases were low. Similarly, even when a very small amount of hardly desorbed substance is contained in the water to be treated, there is a problem that the adsorbent deteriorates if the adsorption / desorption operation is performed for a long time.

JP 2006-55712 A

  The present invention has been made against the background of the above-described technology, and it has a low boiling point for water to be treated which contains an adsorbed substance having a low boiling point as a main component and also has an adsorbed substance having a high boiling point and hardly desorbed. It is an object of the present invention to provide a water treatment device that can be stably removed with high efficiency and at a low cost, and has an improved economy by reducing the frequency of replacement of adsorbents.

As a result of intensive studies in order to solve the above problems, the present inventors have finally completed the present invention. That is, the present invention is as follows.
(1) It includes a fibrous adsorbing element that adsorbs an adsorbed substance by contacting water to be treated containing two or more adsorbed substances, and desorbs an adsorbed substance adsorbed by contacting water vapor; An adsorption process for adsorbing a substance to be adsorbed to the adsorbing element by supplying the water to be adsorbed to the adsorbing element and discharging it as treated water; and supplying the substance to be adsorbed by supplying low-temperature water vapor to the adsorbing element A desorption step of desorbing, condensing, and discharging water containing the adsorbed substance as concentrated water, and performing an adsorption / desorption operation in which the adsorption step and the desorption step are alternately repeated, Removing the adsorbed substance from the water, purifying the water, performing the adsorption / desorption operation for a certain period of time, and then performing a regeneration step of regenerating the adsorption element by supplying high temperature steam to the adsorption element; Then absorb and desorb Water treatment apparatus characterized by resuming operation.
(2) The water treatment apparatus according to (1), wherein a gas is supplied between the adsorption step and the desorption step to remove excess water to be treated adhering to the adsorption element and discharge it as removed water.
(3) The water treatment apparatus according to (2), wherein the gas used for removing the removed water is water vapor.
(4) The water treatment apparatus according to (2) or (3), wherein the removed water is supplied as treated water.
(5) The water treatment apparatus according to any one of (1) to (4), wherein the temperature of the low temperature steam is 100 ° C. or higher and lower than 140 ° C., and the temperature of the high temperature steam is 140 ° C. or higher and 450 ° C. or lower.
(6) The water to be treated containing the two or more kinds of adsorbed substances includes at least one kind of adsorbed substance having a boiling point of less than 140 ° C. and 140 ° C. or more, respectively (1) to (5) Water treatment equipment.

  The water treatment apparatus according to the present invention continuously removes the adsorbed substances in the treated water with high efficiency even in the water treatment in which the difficultly desorbed substances to be treated (hereinafter sometimes referred to as “hardly desorbed substances”) coexist. In addition, there is basically no need to replace the adsorbent, and there is an advantage that water can be purified at a low cost.

It is an example of the block diagram of the water treatment apparatus which can be used for implementation of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments shown in the drawings, the same or corresponding parts are omitted as appropriate, and the description thereof will not be repeated.

  FIG. 1 is one of system configuration diagrams of a water treatment apparatus according to an embodiment of the present invention.

  The water to be treated in the present invention contains two or more kinds of adsorbed substances, and includes a low boiling point adsorbed substance that can be easily desorbed with low temperature steam and a hardly desorbed substance that is difficult to desorb with low temperature steam.

  The water treatment apparatus 100 includes a first treatment tank 110 and a second treatment tank 120 in which adsorbents 111 and 121 as adsorption elements are accommodated, respectively. The adsorbents 111 and 121 adsorb the substance to be adsorbed contained in the water to be treated by contacting the water to be treated. Therefore, in the water treatment apparatus 100, by supplying the water to be treated to the adsorbents 111 and 121, the substance to be adsorbed is adsorbed by the adsorbents 111 and 121, whereby the water to be treated is cleaned and discharged as treated water. Will be. The adsorbents adsorbed by adsorbing the water vapor to the adsorbents 111 and 121 are desorbed. The water vapor discharged from the first treatment layer 110 and the second treatment layer 120 and the adsorbed substance desorbed are cooled and condensed by the condenser 130, and are discharged out of the water treatment apparatus 100 as concentrated water.

  In the first treatment tank 110 and the second treatment tank 120, there are pipes for a treated water (raw water) supply line, a treated water discharge line, a low temperature steam supply line, a high temperature steam supply line, and a concentrated water discharge line. Each line is connected to a flow path switching means that is switched to a connected / disconnected state with respect to each processing tank using a valve or the like.

  Next, the adsorption / desorption operation using low-temperature steam (repeated operation of the adsorption process and the desorption process) will be described. The 1st processing tank 110 and the 2nd processing tank 120 function as an adsorption tank and a desorption tank alternately by operating opening and closing of the valve mentioned above. When the 1st processing tank 110 is functioning as an adsorption tank, the 2nd processing tank 120 functions as a desorption tank. Specifically, when the water to be treated (raw water) is supplied to the first treatment tank 110 and a flow path is secured so that the treated water is discharged from the first treatment tank 110, the second treatment tank 120 is A low-temperature steam is supplied, and the concentrated water is discharged from the second treatment tank 120. The water treatment apparatus 100 according to the present embodiment is configured such that the adsorption tank (adsorption process) and the desorption tank (desorption process) are alternately switched over time.

  By the adsorption / desorption operation using the low temperature steam described above, the low boiling point adsorbed substances are adsorbed on the adsorbents 111 and 121 and removed from the water to be treated, and desorbed from the adsorbents 111 and 121 by the low temperature steam and concentrated water. It is contained and discharged. Since the hard-to-desorb substance is difficult to desorb with low-temperature steam, it is basically not contained in concentrated water, and remains in the adsorbents 111 and 112 even after desorption with low-temperature steam.

  Next, regeneration using high-temperature steam will be described. When the adsorption / desorption operation with low-temperature steam is performed for a certain period of time, the pores necessary for adsorption of the low-boiling point adsorbed substances are blocked by the influence of the hardly-desorbed substances remaining on the adsorbents 111 and 121, and the adsorption efficiency decreases. Start to do. At this stage, high-temperature steam is supplied to the first treatment tank 110 and the second treatment tank 120, and the adsorbents 111 and 121 are regenerated. Specifically, the first treatment tank 110 will be used to explain that the low-boiling point adsorbed substance is desorbed from the adsorbent 111 by the desorbed substance adsorbed on the adsorbent 111 by supplying high-temperature steam to the first treatment tank. Occlusion of the pores necessary for the adsorption of the substance disappears (regeneration), and the desorbed difficult-to-desorb substance is contained in the reclaimed water and discharged. When the regeneration is completed, the operation shifts to an adsorption / desorption operation using low-temperature steam.

  Although not shown, when the water treatment apparatus 100 is switched from the adsorption tank to the desorption tank, the water adhering to the adsorbents 111 and 121 is removed (dehydrated) and discharged as removed water, and then desorption is started. Is preferred. This is because the desorption efficiency can be improved by performing desorption after removing the adhering water from the adsorbents 111 and 121 in advance. As the means for removing the adhering water, means such as self-weight removal, high-speed purging with a high-pressure gas such as compressed air, nitrogen, and steam, and suction using a vacuum pump can be used, but steam is preferred. This is because no purge gas is generated by the purge process, so that a separate gas processing apparatus is not required and the processing tank can be preheated, so that the desorption efficiency is increased.

  Further, it is preferable that the removed water is returned to the water to be treated and treated again. This is because it is not necessary to separately process the removed water with another water treatment apparatus.

  Moreover, although FIG. 1 demonstrated using two processing tanks, the number of processing tanks is not specifically limited. For example, the treatment tank may be a single tank, and water to be treated may be stored in a tank or the like during desorption and regeneration and adsorbed after desorption and regeneration. Further, the number of processing tanks may be three, and while the two processing tanks are performing the adsorption / desorption operation, the remaining one processing tank may be regenerated and sequentially performed.

  The temperature of the low-temperature steam in the embodiment of the present invention is preferably 100 ° C. or more and less than 140 ° C. If the temperature is lower than 100 ° C., the water vapor is condensed and the amount of heat necessary for desorption cannot be obtained. If the temperature is 140 ° C. or higher, the water vapor must be heated secondarily, which is economically disadvantageous. The pressure of water vapor is not particularly limited.

  The temperature of the high-temperature steam in the embodiment of the present invention is preferably 140 ° C. or higher and 450 ° C. or lower. If the temperature is lower than 140 ° C., it is difficult to desorb the hard-to-desorb substance. If the temperature exceeds 450 ° C., the risk of embrittlement of the adsorbent increases. There are methods for supplying high-temperature steam, such as supplying high-pressure steam or secondarily heating low-pressure steam to superheated steam. Although there is no particular limitation, superheated steam is used from the viewpoint of avoiding the pressure-resistant structure of the treatment tank. It is better to adopt.

  The concentrated water in the embodiment of the present invention may be appropriately subjected to secondary treatment according to the physical properties of the substance to be adsorbed. For example, after the concentrated water is aerated and the adsorbed substances are removed by volatilization, the aeration gas containing the volatilized adsorbed substances is combusted with a combustion apparatus (for example, catalytic oxidation apparatus), or the concentrated water is treated as a waste liquid combustion apparatus. There is a method of processing in the case of the above, and in the case where the substance to be adsorbed is a valuable material, there is a method of concentrating with a distillation facility or an evaporation concentrator and reusing it. Further, the reclaimed water may be appropriately subjected to secondary treatment according to the physical properties of the hardly desorbable substance. A secondary treatment may be performed by mixing with the concentrated water, or a secondary treatment may be performed separately.

  The low boiling point adsorbed substance in the embodiment of the present invention is an adsorbed substance having a boiling point of less than 140 ° C. For example, ethyl acetate, propyl acetate, butyl acetate, dichloromethane, dichloroethane, trichloroethylene, isopropyl alcohol, ethanol, butanol, benzene, toluene, xylene, ethylbenzene, 1,4-dioxane, 2-methyl-1,3-dioxolane, dioxolane, Acetic acid, methyl ethyl ketone, methyl isobutyl ketone, hexane, propylene glycol monomethyl ether and the like.

  The hardly desorbable substance in the embodiment of the present invention is a substance having a boiling point of 140 ° C. or higher. As described above, organic substances such as organic polymers, organic oligomers, proteins, sugars, fatty acids, fatty acid esters, amines, amide compounds, oils and fats, resins, surfactants, dioxins, high-boiling solvents, sulfates, sulfides, It is an inorganic substance such as iron rust. In addition, organic substances that undergo a polymerization reaction during desorption and become a resin on the surface of the adsorbent are also included in the difficult desorption substances. For example, cyclohexanone, acrylic acid ester, epichlorohydrin, adipic acid and the like.

  By using the water treatment apparatus described above, the water treatment apparatus 100 uses low-temperature steam for desorption in normal operation, and the high-temperature steam is used only when regeneration of the adsorbent is necessary. Therefore, it is possible to remove the substance to be adsorbed from the water to be treated with high efficiency.

  Further, in the embodiment of the present invention described above, the description has been made without particularly showing the components such as the fluid conveying means such as the pump and the fluid storing means such as the storage tank, but these components are necessary. Accordingly, it may be arranged at an appropriate position.

  Thus, the above-described embodiments disclosed herein are illustrative in all respects and are not restrictive. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Evaluation was performed by the following method.
(BET specific surface area)
The BET specific surface area was measured by measuring the amount of nitrogen adsorbed on the sample when the relative pressure was raised in the range of 0.0 to 0.15 in the atmosphere of the boiling point of liquid nitrogen (-195.8 ° C), and a BET plot. Was used to determine the surface area (m ² / g) per unit mass of the sample.
(Adsorbed substance removal effect)
The water to be treated was 1,4-dioxane 10 mg / L and cyclic trimer (CT) 0.1 mg / L. Cyclic trimer is an organic oligomer produced in the process of producing polyethylene terephthalate. The 1,4-dioxane and CT concentrations entering and exiting the water treatment apparatus were measured, and the amount of each adsorbed substance discharged was calculated to confirm the removal effect.
(Adsorbed substance concentration evaluation)
1,4-dioxane was quantified by gas chromatography, and CT was quantified by liquid chromatography.

[Example 1]
As the system, the embodiment shown in FIG. 1 was used.
^Two adsorbing elements with a weight of 0.2 kg using activated carbon fibers having a BET specific surface area of 2000 m ² / g as an adsorbent for the water treatment apparatus are prepared and installed in the water treatment apparatus of FIG. It introduced so that the amount of treated water might be 50 L / h, and obtained treated water.

  Next, 120 ° C. low temperature steam was supplied to remove (dehydrate) adhering water from the adsorbent, and the removed water was returned to the raw water. Next, desorption was carried out by supplying low-temperature steam at 120 ° C. to the adsorbent. The desorption gas discharged from the adsorption element was recovered as concentrated water after cooling and condensation. The adsorption / desorption operation was carried out as a switching cycle with an adsorption time of 20 min, a dehydration time of 0.5 min, and a desorption time of 2 min. The 1,4-dioxane concentration in the treated water 10 hours after the start of operation was 0.05 mg / L or less, and the CT concentration was 0.01 mg / L or less.

  800 hours after the start of operation, the adsorption / desorption operation was temporarily stopped, and regeneration was performed by supplying 19.5 min of high-temperature steam obtained by heating 120 ° C. low-temperature steam to 300 ° C. with an electric heater. The regeneration gas discharged from the adsorption element was recovered as regeneration water after cooling and condensation. After completion of regeneration, the adsorption / desorption operation was resumed under the same conditions as described above. As shown in Table 1, the 1,4-dioxane concentration in the treated water 200 hours after the resumption of the adsorption / desorption operation (about 1000 hours after the start of operation) is 0.05 mg / L or less, and the CT concentration is 0.01 mg / L. The adsorbed substances could be removed stably with high efficiency.

In addition, as shown in Table 2, the adsorbent before and after regeneration was collected and the BET specific surface area was measured, and it was 1500 m ² / g (according to the values in Table 2) before regeneration, but after regeneration. Is 2000 m ² / g, and the adsorbent is regenerated to a specific surface area before operation by high-temperature steam.

  As shown in Table 3, the amount of low-temperature water vapor used for desorption and regeneration in 1000 hours was 1120 kg, the high-temperature water vapor amount was 10 kg, and the electric power used by the electric heater was 0.2 kw.

[Comparative Example 1]
The water treatment apparatus of Example 1 was subjected to an adsorption / desorption operation for 1000 hours without regeneration with high-temperature steam. As shown in Table 1, the 1,4-dioxane concentration in the treated water at that time was 5 mg / L, which was 10 times the concentration of Example 1.

Moreover, as shown in Table 2, when the BET specific surface area after 1000-hour adsorption / desorption operation was measured, it was 1500 m < ² > / g, and the specific surface area of 500 m < ² > / g was reduced.

[Comparative Example 2]
The water treatment apparatus of Example 1 was subjected to an adsorption / desorption operation for 1000 hours using high-temperature steam at 300 ° C. in the desorption step without a regeneration step. The 1,4-dioxane concentration in the treated water at that time was 0.05 mg / L or less, and the CT concentration was 0.01 mg / L or less.

Moreover, when the BET specific surface area after 1000-hour adsorption / desorption operation was measured, it was 2000 m < ² > / g, and it resulted in the reduction of a specific surface area.

  However, as shown in Table 3, the amount of low-temperature water vapor used for desorption in 1000 hours was 360 kg, the high-temperature water vapor amount was 9000 kg, and the electric power used by the electric heater was 180 kW, which is a result of using a very heat source compared to Example 1. It was.

100: Water treatment device 110: First treatment tank 111: Adsorbent 120: Second treatment tank 121: Adsorbent 130: Condenser

Claims (7)

An adsorption process comprising a treatment tank in which an adsorbing element is accommodated and a piping line connected to the treatment tank, and adsorbing the adsorbed substance by bringing water to be treated containing two or more adsorbed substances into contact with the adsorbing element If, by carrying out desorption operation repeated alternately and desorption process for desorbing the adsorbed substances adsorbed by contacting the water vapor to the suction device, the water treatment device for cleaning the water to be treated,
After the adsorption-desorption operation carried a certain time, the supplied high-temperature high-temperature steam than the steam suction device carried a reproduction process for reproducing the adsorption element, after the regeneration process, resuming the adsorption-desorption operation The water treatment apparatus characterized by performing. The water treatment apparatus according to claim 1, wherein a gas is supplied between the adsorption process and the desorption process to remove excess water to be treated adhering to the adsorption element and discharge it as removed water.   The water treatment apparatus according to claim 2, wherein the gas used for removing the removed water is water vapor.   The water treatment apparatus according to claim 2 or 3, wherein the removed water is supplied as treated water. The temperature of the steam is lower than 140 ° C. 100 ° C. or higher, the water treatment apparatus according to any one of claims 1 to 4 the temperature of the high-temperature water vapor is 450 ° C. or less 140 ° C. or higher. The treated water containing two or more of the adsorption material, according to any one of 5 and the adsorbed substance and 140 ° C. or more adsorbates having a boiling point of lower than 140 ° C. claim 1, each containing more than one Water treatment equipment.   In a water treatment method for cleaning water to be treated using an adsorption element,
  An adsorption process in which water to be treated containing two or more kinds of substances to be adsorbed is brought into contact with the adsorption element to adsorb the substance to be adsorbed, and a desorption process in which the adsorbed substance adsorbed by bringing water vapor into contact with the adsorption element is desorbed. And an adsorption / desorption process that repeats alternately,
  And a regeneration step of regenerating the adsorbing element by supplying the adsorbing element with high-temperature steam at a temperature higher than the water vapor after performing the adsorption / desorption process for a certain period of time.
  The water treatment method characterized by restarting the adsorption / desorption step after the regeneration step.