JP2016198742A - Liquid treatment system, solution processing device and solution treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment system and a water treatment method excellent in removal performance of an adsorbate adhered to an adsorption structure body in a solution treatment system having an adsorption part having the adsorption structure body, capable of repeating recycle use of the adsorption structure body and having reduced treatment cost.SOLUTION: There are provided a water treatment system which is a solution treatment system having an adsorption part M with a porous ceramic honeycomb structure body 22 using ceramic having alumina on its surface and has a mechanism for supplying ozone gas with a gaseous state to an adsorption structure body 22 and a method therefor.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a solution processing system, a solution processing apparatus, and a solution processing method.

  There is known a solution processing system that removes unnecessary components from a solution to make the solution more suitable for the purpose. In particular, water treatment systems for treating water are often used.

  In the water treatment system, a separation membrane that removes a substance to be separated from raw water is used. However, when fouling occurs in the separation membrane, the separation performance for removing the substance to be separated from the raw water is deteriorated.

  Therefore, before supplying the raw water to the separation membrane, there is a method for selectively removing from the raw water the substances to be separated that cause deterioration of the performance of the separation membrane by pre-adsorbing them on the adsorbent provided in the previous stage of the separation membrane. Are known. As a result, it is possible to extend the exchange life of the separation membrane.

  However, even in such an adsorbent, the adsorbate gradually accumulates with the passage of water passage time, and the adsorbent adsorption performance decreases. If the adsorption performance of the adsorbent is reduced, the effect of preventing fouling (clogging) in the separation membrane cannot be obtained.

  As a technique for decomposing and removing organic substances adsorbed on the adsorbent, for example, in Patent Document 1, organic substances in wastewater are brought into contact with and adsorbed on a supported catalytic magnetic adsorbent, and ozone gas or hydrogen peroxide is injected into the wastewater. Also disclosed is a method for oxidizing and decomposing organic substances adsorbed on a supported catalyst type magnetic adsorbent by contacting and adsorbing ozone gas or hydrogen peroxide to the supported catalyst type magnetic adsorbent in waste water.

  In Patent Document 2, an organic substance such as trihalomethane contained in the water to be treated is adsorbed on the adsorbent 6 of the adsorbent layer 7, and ozone gas is injected from the ozone injector 8 into the water to be treated. 6 discloses a water treatment apparatus in which organic matter and ozone gas are brought into contact with each other for accelerated oxidation (AOP).

JP 2008-284520 A JP 2005-111407 A

  Even in the techniques of Patent Document 1 and Patent Document 2, for example, when the organic matter in seawater is removed by adsorption, the adsorbent adhering to the adsorbent cannot be sufficiently removed depending on the type of the removal target, and the adsorbent is adsorbed. There is a problem that performance degradation cannot be prevented. If the adsorption performance of the adsorbent decreases, fouling occurs in the separation membrane provided on the rear stage, and it is necessary to increase the operation output of the treatment system in order to obtain the same amount of treated water as before fouling. It becomes.

  In addition, if the filtration performance of the separation membrane does not recover even after washing the membrane surface of the fouled separation membrane, it is necessary to replace the separation membrane element, and the water treatment system is stopped by stopping the water treatment system for a long time. Lowering the operating rate, increasing the running cost due to the addition of replacement parts and replacement work costs increase the processing cost of the entire water treatment system.

  Therefore, the present invention provides a water treatment system and a water treatment method that are excellent in the removal performance of adsorbed substances adhering to the adsorption structure, can be repeatedly used for the adsorption structure, and have reduced treatment costs. The issue is to provide.

  In order to solve the above problems, an example of the present invention is a solution processing system including an adsorption unit having an adsorption structure and a mechanism for supplying gaseous ozone gas to the adsorption structure.

A further example of the present invention is a solution processing system characterized in that the adsorption structure is made of ceramic.
A further example of the present invention is a solution processing system, wherein the ceramic has a hollow structure, and a solution is supplied to the hollow structure portion.
A further example of the present invention is a solution processing system characterized in that the ceramic is porous.

In another example of the present invention, the adsorbing structure includes an outer wall, a plurality of flow paths provided inside the outer wall, and a partition that separates each of the plurality of flow paths from each other, The partition wall is a solution processing system having a porous ceramic honeycomb structure having a plurality of communication holes that allow communication between adjacent flow paths and having an adsorption portion formed by the partition wall.
A further example of the present invention is a solution processing system characterized in that the surface of the ceramic is alumina.
A further example of the present invention is a solution processing system in which the ceramic has a honeycomb shape or a sponge shape.
Further, a further example of the present invention is a solution processing system characterized by including a filtration unit having an RO membrane downstream of the adsorption unit.

  Further configurations and effects of the present invention will become apparent from the disclosure of the entire specification below.

  According to the present invention, it is excellent in the removal performance of the adsorbed substance adhering to the adsorbing structure, can be repeatedly used and reused, the adsorbing structure is not frequently replaced, and the processing cost is reduced. In addition, a solution processing system, a solution processing apparatus, and a solution processing method can be realized.

It is explanatory drawing of one Example of this invention. It is explanatory drawing of one Example of this invention. It is the schematic of one Example of this invention. It is sectional drawing of an example of an adsorption | suction module. It is an end view on the inflow side showing an example of a porous ceramic honeycomb adsorbent, (a) is an end view when the cross section of the flow path in a direction orthogonal to the direction in which water flows is a square, and (b) is water It is an end view in case the cross section of the flow path of the direction orthogonal to the direction which flows is a triangle. It is sectional drawing along the direction through which water flows of a porous ceramic honeycomb adsorbent. It is a figure which shows schematic structure of the QCM apparatus used for evaluation of the adsorption performance and removal performance of a natural organic substance. 5 is a graph showing the adsorption time dependence of the amount of mannan adsorption on the QCM sensor 41. It is a graph which shows the removal rate curve obtained by correcting the removal rate curve of the mannan on the QCM sensor 41 and its rate constant together with the plot of the measured value of the mannan removal rate of the porous ceramic honeycomb adsorbent. . It is a schematic diagram for demonstrating a state when the QCM sensor 41 is wash | cleaned with ozone gas. It is a graph which shows the recovery rate of adsorption | suction performance when the adsorbate adhering on an alumina is wash-processed. It is the graph which compared the processing time dependence of each recovery rate when ozone dissolved water and ozone gas are used for the washing | cleaning after adsorption processing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, hatching may be added to make the drawings easy to see even if they are not cross-sectional views. In all the drawings for explaining the following embodiments, components having the same function are denoted by the same reference numerals in principle, and repeated description thereof is omitted.

  FIG. 1 is a schematic explanatory view of a solution processing system of the present invention. 100 is a pre-treatment solution and its reservoir, 101 is a pump, 110 is a valve 1, 102 is an adsorption device, 103 is a filtration device, 130 is a waste solution, and 140 is a post-treatment solution. The present invention further includes a 120 ozone source and a 111 valve 2.

  The normal operation of the solution processing system of the present invention will be described. The pre-treatment solution 100 is pressurized by the pump 101, passes through the opened valve 1 110, and is sent to the adsorption device 102. Here, impurities such as organic substances are adsorbed. Thereafter, the solution is sent to the filtration device 103 and a treated solution is obtained as 140. Further, unnecessary substances removed at that time are discharged as a waste solution 130.

  At this time, when the operation of the system takes a long time, a large amount of impurities adhere to the adsorption device, and the removal efficiency thereof decreases. As a result, there is a problem that the removal rate of the removing device is reduced, the flow rate is lowered, and the operation rate and processing capacity are reduced.

  Therefore, the present invention is characterized in that ozone gas can be supplied to the adsorption device in a state in which the solution is excluded, and organic substances can be decomposed directly by the ozone gas.

  The operation during the decomposition of organic matter will be described. By closing the valve 110, the supply of the pre-treatment solution 100 to the adsorption device 102 is stopped. In this state, the valve 2 111 is opened. As a result, ozone gas is supplied from the ozone source 120 to the adsorption device 102. The residual solution is first discharged by gravity. Further, the residual solution in the adsorption device is dried and excluded by the gas. In the adsorption device, ozone gas is directly supplied in a gaseous state, so that organic substances adhering in the adsorption device are efficiently decomposed into ozone. As a result of measurement by the inventors, this method of supplying gaseous ozone directly to the adsorption device is an experiment simulating seawater treatment compared to the case where the adsorption device is washed by supplying the same amount of ozone gas into the solution. It has been found that a remarkable effect of achieving a removal efficiency of 20 times or more is achieved.

  By returning to the normal operation again after the organic matter decomposition is completed, the organic matter decomposed in the decomposition step is discharged as a waste solution 130 by the filtration device 103. Of course, the adsorption device 102 may be provided with a dedicated discharge structure for discharging decomposition products.

  As described above, the present invention provides a solution that can maintain a high operation rate and a high processing capacity by adopting a configuration capable of supplying gaseous ozone gas to the adsorption unit in the solution processing system having the adsorption unit. A processing system was realized.

  In addition, the present invention is a solution processing apparatus having an adsorption unit, and has a mechanism for supplying gaseous ozone gas to the adsorption unit, thereby realizing a solution processing apparatus capable of maintaining a high operation rate and high processing capacity. .

  Furthermore, for a solution processing system having an adsorption unit, a first step of flowing water to be treated containing a substance to be separated into the adsorption unit, and a first step of discharging the water to be treated of the adsorption unit after the first step And a third step of passing ozone gas through the adsorption portion after the second step.

  In addition, although the above showed the example which used ozone gas as gas which decomposes | disassembles organic substance, even if it is gas other than ozone gas, what has the decomposition | disassembly capability of organic substance is included in the category of a present Example. However, ozone gas is considered desirable in practice because of its ease of manufacture.

  The feature of the present embodiment is that ceramic is used as a constituent material of the adsorption device of the first embodiment. In the present invention, gaseous ozone gas is supplied to the adsorption device. Gaseous ozone gas has a very high ability to decompose organic substances, and this is the reason why the effects of the present invention can be achieved. At the same time, it is also a sword with a blade that decomposes the components of the adsorption device itself. Therefore, this embodiment is characterized in that ceramic is used as a constituent material of the adsorption device.

  Ceramics are currently applied in various applications as chemically highly stable materials because they are formed at ultra-high temperatures. When an organic material such as plastic is used in the adsorption device of the present invention, the life itself is extremely shortened because it is decomposed. Further, when a metal is used, the ozone gas used in the present invention has a much higher oxidizing ability than oxygen, and therefore oxidizes in a short time. Therefore, by using ceramic with the adsorption apparatus of the present invention, it was possible to realize corrosion prevention against ozone gas while realizing adsorption performance for organic substances.

  The form of the ceramic is not particularly limited. Various forms such as powder, particles, pellets, plate, porous, spherical, square, cylindrical, and honeycomb are applicable.

The feature of the present embodiment is the detailed configuration in the adsorption device 102 of FIG.
An example is shown in FIG. The solution to be treated 150 is introduced into the hollow ceramic pipe 151 from the left side of the figure. Organic matter in the solution to be treated is trapped on the inner surface of the ceramic pipe. The captured organic matter is decomposed and gasified by the subsequent introduction of ozone gas. The solution to be treated passes through the wall surface by making the wall of the ceramic pipe porous, and is discharged as a treatment completion solution 152. This processing completion solution 152 then leaves the adsorption device 102 and is introduced into the filtration device 103.

  In this embodiment, since the organic substance is further separated and removed from the solution to be treated by the adsorption device, impurities in the solution supplied to the subsequent filtration device 103 are reduced, so that the lifetime of the filtration device can be extended. . Moreover, since the flow path is secured in advance, drainage prior to the introduction of ozone gas can be realized in a short time.

  Further, in this embodiment, the example of the ceramic pipe that is excellent in solution processing efficiency per unit space because it is discharged in all directions has been described. However, the processing completion solution 152 is used in the wall material shape portion in one direction through the wall surface. The case where the discharge is configured is included in the category of the present embodiment. In this case, a plate-like ceramic can be used.

  The shape of the ceramic pipe is not limited to a cylindrical shape, but may be a rectangular shape or a polygonal shape. However, a cylindrical shape is practically preferable from the viewpoint of ease of manufacturing the ceramic pipe. In this embodiment, the ceramic pipe has been described as one example. However, an assembly or a laminated structure of a large number of ceramic pipes, ceramic pipes divided into a plurality of sections, or a combination thereof may be used.

  In addition, the term “porous” in the present invention includes cases having a sponge-like structure or a network structure.

In the present embodiment, a case of water as a solution treatment will be described as an example.
In advanced treatment of water purification, a reverse osmosis membrane (hereinafter referred to as RO (Reverse Osmosis) membrane) is used as a separation membrane for removing substances to be separated from raw water, and in this embodiment, as a separation membrane. The case where an RO membrane is used will be described as an example. RO membranes are used for the production of pure water used in the production of precision electronic equipment such as semiconductors, the removal of organic substances dissolved in water in advanced treatment of water and final treatment of sewage / drainage, or the removal of electrolytes in seawater desalination. .

  In a present Example, although the case of the seawater desalination system and seawater desalination method which perform seawater desalination using RO membrane is demonstrated to an example, this invention is not necessarily limited to a seawater desalination system. Applying to applications other than seawater desalination, such as a reused water production system that purifies wastewater and produces recycled water, and a pure water / ultrapure water production system that produces pure water or ultrapure water Is also possible.

  In this embodiment, a seawater desalination system using an RO membrane will be described. However, the present invention is not necessarily limited to the one using an RO membrane. For example, a microfiltration membrane (hereinafter referred to as MF (Microfiltration) membrane) is used. Or a water treatment system using an ion exchange membrane.

  Seawater desalination using an RO membrane is performed, for example, through the following processing process. First, a fine suspension such as sand contained in seawater is separated by filtering with an ultrafiltration membrane (hereinafter referred to as UF (Ultrafiltration) membrane), subsiding in a sedimentation basin, or a combination of both. At this time, a floc may be formed by adding a flocculant or the like to the suspension as necessary. When water obtained in this way (hereinafter referred to as pre-treated water) is supplied to one surface of the RO membrane while being pressurized, the other surface of the RO membrane contains almost no electrolytes or organic substances for drinking. Suitable water (hereinafter referred to as permeate) is obtained. Seawater contains 20 to 40 g / L of sodium chloride as an electrolyte, but when water is passed through the RO membrane, the electrolyte is separated, and the electrolyte concentration of the permeated water can be reduced to 1 mg / L or less.

  On the other hand, the above-mentioned pretreatment water contains organic substances and the like, and some of them are adsorbed on the surface of the RO membrane and inhibit the osmotic action. In order to prevent such inhibition of the osmotic action, in the following embodiment, an adsorption structure for removing organic substances contained in the pretreated water is not particularly limited in the previous stage of the RO membrane, but the porous ceramic honeycomb adsorbent is not limited. The structure provided with 22 (refer FIG. 3) is demonstrated. In the following embodiments, a ceramic adsorption structure that is not in a honeycomb shape can be used instead of the porous ceramic honeycomb adsorbent. For example, a particulate ceramic adsorbent filled in a column (cylindrical casing) may be used, or a plate-shaped ceramic adsorbent (such as a QCM sensor described later) may be used. By using the particulate ceramic adsorbent packed in the column and the plate-shaped ceramic adsorbent, organic substances can be adsorbed in the same way as the porous ceramic honeycomb adsorbent, and as will be described later, the organic substances after adsorption are removed by washing. can do. However, when the porous ceramic honeycomb adsorbent is used, in the drainage process described later, the pressure loss (hereinafter referred to as pressure loss) is lower than the particulate ceramic adsorbent packed in the column, so that the drainage efficiency is increased. There are advantages. Pressure loss refers to the amount of energy (fluid pressure per unit volume) that is lost when a fluid (for example, water) flows in a pipeline. The fluid receives resistance due to friction with the wall surface and the wall shape. This is a phenomenon in which the pressure decreases toward the downstream side. Specifically, the difference between the pressure at the inlet (supply side) of the fluid pipeline and the pressure at the outlet of the pipeline is called pressure loss. At this time, the pressure loss increases as the resistance in the pipe increases. The resistance is proportional to the length of the pipeline and inversely proportional to the thickness of the pipeline. Furthermore, in a portion where the cross section of the pipe line changes suddenly or the pipe line is bent, a vortex or the like is generated in the flow, so that the resistance increases.

  Based on the above, after replacing the pipe with a flow path, the resistance is compared in terms of the shape of the flow path between the porous ceramic honeycomb adsorbent and the particulate ceramic adsorbent filled in the column. The channel diameter of the porous ceramic honeycomb adsorbent is, for example, about 0.5 to 5 mm, and the channel is a straight line. On the other hand, since the flow path of the particulate ceramic adsorbent filled in the column is formed by the gap between the particles, the flow path diameter is very thin, and the flow path is not straight. Has a bend. Accordingly, the resistance received by the fluid in the flow path is lower in the porous ceramic honeycomb adsorbent than in the particulate ceramic adsorbent filled in the column, and the pressure loss is also reduced.

Since the drainage is performed quickly at low pressure loss, the porous ceramic honeycomb adsorbent is advantageous in terms of the process because the drainage process time can be shortened. Furthermore, when a porous ceramic honeycomb adsorbent is used, the adsorption area per unit volume is much larger than that of a plate-shaped ceramic adsorbent, so an adsorption process that requires a large adsorption area, such as a water treatment system. This is advantageous in reducing the installation area of the adsorption structure. For the above reasons, in the following embodiment, a porous ceramic honeycomb adsorbent 22 which is a particularly preferable embodiment will be described.
<Configuration of seawater desalination system>
Below, the water treatment system and water treatment method which concern on a present Example are demonstrated using FIG. As shown in FIG. 3, the seawater desalination system 1 according to the present embodiment removes salt, organic matter, microorganisms (including fungi), boron, solid suspended matters, and the like contained in seawater as substances to be separated for desalination. This is a water treatment system that consists of three parts in the order of the seawater intake part 10, the pretreatment part 20, and the desalination part 30 from the upstream side.

  The seawater intake unit 10 includes an intake pipe 11, an intake pump 12, and a raw water tank 13. The intake pipe 11 may be configured to absorb the seawater as raw water installed in the sea, or may be configured to extend to the offshore and absorb deep water as raw water, or buried in the seabed and filtered with seabed sand. The structure which sucks up the seawater used as raw water later may be sufficient. The intake pump 12 may be configured to be installed in the sea as well as configured to be installed on land. Further, in order to prevent organisms such as microorganisms, algae and shellfish from growing in the intake pipe 11 and blocking the intake pipe 11, chemicals (for example, bactericides) that prevent the growth of these organisms are contained in the intake pipe 11. It is good also as a structure inject | poured into.

  The pretreatment unit 20 includes, for example, a sand filtration tank 21, a porous ceramic honeycomb adsorbent 22 as an adsorption structure, a water feed pump 22a, and an RO membrane supply water tank 23, and sterilizes microorganisms and other suspended components. Perform pre-processing to be removed. In addition, the pretreatment unit 20 includes a chemical injection system 24 that injects a plurality of types of chemicals into raw water. The medicinal injection system 24 is configured according to the type of chemical injected into the raw water. The suspended component is often an organic substance. Moreover, it may have an inorganic substance. Further, the pretreatment unit 20 is provided with an ozone supply system 25 for supplying ozone to the porous ceramic honeycomb adsorbent 22 and removing organic substances adsorbed on the porous ceramic honeycomb adsorbent 22. The detailed configuration and function of the porous ceramic honeycomb adsorbent 22 will be described later.

  In the present embodiment, in the removal process of adsorbents such as organic substances adsorbed on the porous ceramic honeycomb adsorbent 22, ozone supply described later is performed in a state where water is discharged from the porous ceramic honeycomb adsorbent 22 as will be described later. Ozone gas is supplied from the system 25, and ozone is brought into contact with the porous ceramic honeycomb adsorbent 22 as ozone gas. For this reason, the pretreatment unit 20 has a mechanism for discharging the treated water held by the porous ceramic honeycomb adsorbent 22 from the porous ceramic honeycomb adsorbent 22 prior to the supply of ozone gas from the ozone generator 25a. ing.

  Specifically, in the pretreatment unit 20, a pressure release valve VL6 is provided at one end of the porous ceramic honeycomb adsorbent 22, and an adjustment valve VL7 for adjusting the amount of drainage is provided at the other end. The treated water held by the porous ceramic honeycomb adsorbent 22 is discharged by the pressure release valve VL6 and the regulating valve VL7 attached to both ends of the porous ceramic honeycomb adsorbent 22.

  By supplying ozone gas in a state where moisture is excluded from the porous ceramic honeycomb adsorbent 22, it is adsorbed on the porous ceramic honeycomb adsorbent 22 as compared with the case of using ozone-dissolved water in which ozone is dissolved in water. The removal efficiency of adsorbents such as organic substances can be dramatically improved. In addition, the improvement of the removal efficiency by using ozone gas can be obtained also in the particulate ceramic adsorbent filled in the column other than the porous ceramic honeycomb adsorbent or the plate-shaped ceramic adsorbent. In the study by the present inventors, it has been confirmed that the removal efficiency of 20 times or more can be obtained with the porous ceramic honeycomb adsorbent when ozone gas is used as compared with the case where ozone dissolved water is used. .

  In FIG. 1, the chemical injection system 24 is provided with a bactericide injecting section 24a, a pH adjusting agent injecting section 24b, a flocculant injecting section 24c, and a neutralizing / reducing agent injecting section 24d. The sterilizing agent injection unit 24a injects a sterilizing agent that sterilizes microorganisms. The pH adjuster injection unit 24b injects a pH adjuster for preventing the generation of scale due to multivalent ions and improving the aggregation efficiency. The flocculant injection part 24c injects the flocculant for efficiently removing organic substances in the sand filtration tank 21. The neutralizing / reducing agent injection unit 24d injects a neutralizing agent and a reducing agent.

  Hypochlorous acid or chlorine is injected into the raw water from the sterilizing agent injecting section 24a as a sterilizing agent for sterilizing microorganisms. The killing rate or survival rate of microorganisms in the raw water changes depending on the interval and concentration of intermittent injection of the bactericide injected from the bactericide injection unit 24a.

  Hypochlorous acid or chlorine injected as a disinfectant reduces the function of the RO membrane provided in the RO membrane module 32 of the desalting unit 30, so that the raw water is reduced before being sent to the RO membrane module 32. The structure which does is preferable. For this reason, it is preferable to avoid excessive injection of the bactericidal agent, and the bactericidal agent injection portion 24a is provided with an adjustment valve VL1 for adjusting the injection amount of the bactericidal agent.

  Moreover, you may inject | pour a disinfectant into the intake pipe 11 from the disinfectant injection | pouring part 24a. In this case, it is preferable that an adjustment valve VL1 for adjusting the injection amount is also provided in a pipe line for injecting the bactericide into the water intake pipe 11.

  In order to prevent the generation of scale due to multivalent ions and improve the coagulation efficiency, the raw water treated in the seawater desalination system 1 is preferably adjusted to be acidic (pH 3 to 5). Therefore, a pH adjuster such as sulfuric acid is injected into the raw water from the pH adjuster injecting section 24b, and the pH is adjusted appropriately. The pH adjuster injection part 24b is provided with an adjustment valve VL2 for adjusting the injection amount of the pH adjuster.

  Further, a flocculant such as polyaluminum chloride or ferric chloride is injected into the raw water from the flocculant injection part 24c. Since the organic matter contained in the raw water is promoted by the flocculant, the organic fine particles having a size of 0.1 μm or more are grown into organic flocs having a size of 1 μm or more by the injection of the flocculant. Thereby, the removal efficiency of the organic substance in the sand filtration tank 21 improves.

  When the amount of the flocculant injected is too small, flocs do not grow properly, and organic matter may pass through the sand filtration tank 21. Further, when the amount of the flocculant injected is excessive, surplus that is not used for floc growth gives a load to the RO membrane provided in the RO membrane module 32 of the desalting unit 30. Accordingly, the flocculant injection portion 24c is provided with an adjustment valve VL3 for adjusting the injection amount of the flocculant.

  From the neutralizing / reducing agent injection part 24d, a neutralizing agent for neutralizing the raw water adjusted to acidic pH 3-5 and a reducing agent for mainly reducing the bactericidal agent are injected into the raw water. The neutralizing / reducing agent injection unit 24 includes an adjustment valve VL4 that adjusts the injection amounts of the neutralizing agent and the reducing agent.

  In FIG. 1, the ozone supply system 25 is provided with an ozone generator 25a and an ozone detoxifying device 25b. The ozone generator 25a generates ozone gas to be supplied to the porous ceramic honeycomb adsorbent 22, and the ozone abatement apparatus 25b decomposes and detoxifies the ozone gas that has passed through the porous ceramic honeycomb adsorbent 22. Is.

  There are three types of ozone generators: electrolysis, ultraviolet, and discharge. Among them, the electrolysis type ozone generator is configured by sandwiching a polymer electrolyte membrane between electrodes, and generates ozone by electrolyzing water, and has a high concentration of 15 to 20 wt.%. Since ozone is generated, it is an advantage that high-concentration ozone water can be generated relatively easily. For example, it is also used to generate high-concentration ozone water for semiconductor wafer cleaning. In the present embodiment, an electrolytic ozone generator is used, but the method of the ozone generator is not particularly limited.

  The ozone generator 25a is provided with an adjustment valve VL5 for adjusting the supply amount of ozone gas, and the ozone detoxifying device 25b is provided with a valve VL8 for exhausting detoxified ozone gas.

  The ozone gas generated by the ozone generator 25a is supplied to the porous ceramic honeycomb adsorbent 22, and after treating the adsorbate, it is rendered harmless by the ozone detoxifier 25b and exhausted from the valve VL8. The exhaust valve VL8 at this time may also serve as the pressure release valve VL6 provided at one end of the porous ceramic honeycomb adsorbent 22.

  Since the seawater desalination system 1 supplies ozone as ozone gas to the porous ceramic honeycomb adsorbent 22, no mechanism for supplying a liquid is provided between the ozone generator 25a and the porous ceramic honeycomb adsorbent 22. It is also an advantage.

  The desalination unit 30 includes a main line LM composed of a high-pressure pump 31, an RO membrane module 32, and a fresh water tank 33, and a sub-line LS composed of an RO membrane module 32, an energy recovery device 34, and a concentrated water tank 35. Prepare. Further, the desalting unit 30 includes a waste water tank 36, a measuring unit, and a chemical injection system 39 for injecting a plurality of types of chemical solutions into the raw water.

  A semipermeable membrane is used for the RO membrane provided in the RO membrane module 32. A semipermeable membrane is a membrane that allows only water molecules to permeate due to the difference between the interaction between the semipermeable membrane and water molecules and the interaction between the semipermeable membrane and the substance to be separated. Some are polyamide-based. Among these, aromatic polyamide RO membranes are widely used for industrial use because of their high water permeation performance and electrolyte removal performance. In this embodiment, an RO membrane made of an aromatic polyamide-based semipermeable membrane is used, but an RO membrane made of a cellulose acetate-based semipermeable membrane may be used.

  The configuration of the RO membrane module 32 is not limited. For example, as an aromatic polyamide RO membrane, a composite membrane structure in which an aromatic polyamide membrane is formed on the surface of a microporous support is often used. Specifically, for example, a composite membrane in which a polyamide membrane (for example, an aromatic polyamide-based semipermeable membrane) having a thickness of 0.1 μm or less is formed on a surface of a microporous support having a thickness of about several hundreds of μm in a spiral shape. The RO membrane module 32 can be constituted by an element folded into two or an element in which hollow fiber membranes are bundled.

  As an element in this case, a cylindrical element having a diameter of 4 inches (about 10 cm), 8 inches (about 20 cm), or 16 inches (about 40 cm) and a length of about 1 m is often used. The RO membrane module 32 is configured by arranging such elements in series in a vessel (pressure vessel).

  In an element in which the RO membrane is folded in a spiral shape, for example, a polyethylene spacer is sandwiched between the membranes in order to prevent the RO membranes from sticking to each other. However, the gap between the spacer and the RO membrane is as narrow as about 0.5 μm. For this reason, a safety filter may be attached upstream of the RO membrane module 32.

  The chemical injection system 39 is configured according to the type of chemical used for cleaning the RO membrane module 32. In FIG. 3, the chemical injection system 39 includes a bactericide injection part 39a for injecting a bactericide that suppresses the growth of microorganisms, an acid injection part 39b for removing scales, and an alkali injection part for removing organic matter. 39c is provided.

  2,2-Dibromo-3-nitrilopropionamide (hereinafter referred to as DBNPA) or the like is injected into the raw water as an antibacterial agent that suppresses the growth of microorganisms from the antibacterial agent injection unit 39a. The killing rate or survival rate of microorganisms in the raw water varies depending on the interval and concentration of intermittent injection of the antibacterial agent injected from the antibacterial agent injection unit 39a. It should be noted that excessive injection of DBNPA or the like injected as a bacteriostatic agent is preferably avoided, and the bactericidal agent injection part 39a is provided with a control valve VL9 for adjusting the injection amount of the bacteriostatic agent.

  In addition, in order to periodically remove the generated scale from the acid injection part 39b, an acid such as sulfuric acid is injected into the raw water. The acid injection part 39b is provided with an adjustment valve VL10 for adjusting the amount of acid injected.

  Further, alkali such as caustic soda is injected into the raw water from the alkali injection part 39c. The alkali injection part 39c is provided with an adjustment valve VL11 for adjusting the injection amount of alkali.

Next, a water treatment method in the seawater desalination system will be described.
In the seawater desalination system 1 according to the present embodiment, raw water taken from the sea through the intake pipe 11 by the intake pump 12 of the seawater intake unit 10 is temporarily stored in the raw water tank 13 and is to be separated from the raw water. After a part of the precipitate has been removed, it is sent to the pretreatment unit 20.

  In the pretreatment unit 20, the raw water subjected to the bactericide injection from the bactericide injection unit 24a, the pH adjustment agent injection from the pH adjustment agent injection unit 24b, and the flocculant injection from the flocculant injection unit 24c is sand. It flows into the filtration tank 21. In the sand filtration tank 21, organic flocs grown to a size of 1 μm or more are mainly filtered and removed by the flocculant, and the raw water that has passed through the sand filtration tank 21 is transferred to the porous ceramic honeycomb adsorbent 22 by the water pump 22a. Sent. In the raw water that has passed through the sand filtration tank 21, organic substances that could not form flocs due to the flocculant are dissolved, but when the porous ceramic honeycomb adsorbent 22 is brought into contact with the porous ceramic honeycomb adsorbent 22, the porous ceramic honeycomb adsorbent It is adsorbed by the interaction with the surface of 22 and separated and removed from the raw water.

  The raw water is pressurized to about 0.1 to 0.5 MPa by a pressurizing means such as a water pump 22a, and is fed to the porous ceramic honeycomb adsorbent 22 (pressure feed). The raw water sent to the porous ceramic honeycomb adsorbent 22 has a higher rate of permeation through the porous ceramic honeycomb adsorbent 22 as the pressure increases, but the ability to separate the substance to be separated from the raw water (so-called separation performance) is reduced. To do.

  The raw water that has passed through the porous ceramic honeycomb adsorbent 22 is injected with a neutralizing agent and a reducing agent from the neutralizing / reducing agent injection part 24d, and the raw water adjusted to be acidic with a pH adjuster is neutralized, The injected germicide is reduced. The raw water is stored in the RO membrane supply water tank 23.

  As described above, in the pretreatment process in the pretreatment unit 20, a process of sterilizing microorganisms by injecting a bactericide, a process of injecting a flocculant to grow organic flocs, and removing organic substances in the sand filtration tank 21. And a step of removing organic substances (especially, organic substances that cannot be formed into flocs with a flocculant and dissolved in water) with the porous ceramic honeycomb adsorbent 22. Furthermore, the process of removing the organic substance adsorbed on the porous ceramic honeycomb adsorbent 22 is performed at regular intervals. The removal process of the adsorbate adsorbed on the porous ceramic honeycomb adsorbent 22 will be described in detail later.

  The raw water stored in the RO membrane supply water tank 23 is pressurized by the high-pressure pump 31 of the desalination unit 30 and sent to the RO membrane module 32 (pressure feed), and the suspended components are contained in the RO membrane provided in the RO membrane module 32. Removed and filtered. The permeated water filtered by the RO membrane module 32 is stored in the fresh water tank 33 as fresh water. On the other hand, the raw water that does not pass through the RO membrane provided in the RO membrane module 32 becomes concentrated water containing suspended components in a state pressurized by the high-pressure pump 31 and is stored in the concentrated water tank 35.

  In some cases, a drainage system for returning the concentrated water stored in the concentrated water tank 35 to the sea, for example, may be provided. In this case, in the drainage system, a process of reducing the salinity concentration or a process of taking out a substance that can be a raw material of the salinity and chemicals is performed.

  In addition, the energy recovery device 34 provided in the desalinization unit 30 is, for example, a turbine that rotates with energy when high-pressure concentrated water (high-pressure water) stored in the concentrated water tank 35 is drained, and power is generated by the rotation of the turbine. The generated power can be used as drive power for the high-pressure pump 31 and the like.

Next, the filtration method of the RO membrane module will be described.
In the seawater desalination system 1 of the present embodiment, there are the following two methods for filtering raw water in the RO membrane provided in the RO membrane module 32.

  One of the filtration methods is a “total amount filtration method”, which is a method in which the entire amount of raw water is passed through the RO membrane. In this method, a substance to be separated that does not pass through the RO membrane is deposited on the membrane surface of the RO membrane. For this reason, when the concentration of the substance to be separated in the raw water passed through the RO membrane is high, or when the operation time is long, the RO membrane micropores are blocked by the accumulation of the substance to be separated, and the amount of permeated water is the operation time. A phenomenon that decreases with the occurrence of fouling occurs.

  Another one of the filtration methods is a “cross flow filtration method”, which is a method in which raw water flows along the membrane surface of the RO membrane, and a part thereof passes through the RO membrane. In this method, since the substance to be separated that does not permeate the RO membrane is discharged together with the raw water, the substance to be separated is basically difficult to deposit on the membrane surface of the RO membrane. However, even with the cross-flow filtration method, if the operation time is long, the substance to be separated contained in the raw water is gradually adsorbed on the RO membrane and the micropores are blocked. For this reason, even in the cross flow filtration method, fouling gradually occurs as the operation time becomes longer. In this embodiment, the cross-flow filtration method is used, but the whole-volume filtration method may be used.

  The adsorbate (substance to be separated) adsorbed on the RO membrane includes organic fouling that adsorbs organic matter contained in the pretreatment water, scale in which the electrolyte is deposited at a high concentration near the membrane surface of the RO membrane, pretreatment water And biofouling in which microorganisms contained in the cell grow on the surface of the RO membrane.

  Regarding biofouling, when organic matter scales are adsorbed and accumulated on the RO membrane, microorganisms grow using the organic matter as a medium, and a biofilm is formed, which causes biofouling. In the case of the seawater desalination system 1, most of the microorganisms contained in the raw water are killed by the sterilizing agent injected from the sterilizing agent injecting section 24a. However, hypochlorous acid or chlorine used as a disinfectant reacts slightly with the RO membrane (especially aromatic polyamide RO membrane) and gradually decomposes and deteriorates. In order to prevent such deterioration of the RO membrane, the raw water fed to the desalting unit 30 is in a state in which the sterilizing component contained in the sterilizing agent is reduced by the reducing agent as described above.

  The pipes and other components that make up the desalination unit 30 are thoroughly cleaned after construction, and are regularly cleaned with chemicals after the start of use, but it is impossible to completely eliminate microorganisms from the pipes and other components. It is. Further, microorganisms that cannot be sufficiently sterilized by the sterilizing agent injected from the sterilizing agent injecting unit 24 a may flow into the desalting unit 30. For these reasons, microorganisms may flow in and stay in the desalting unit 30 (more specifically, downstream of the RO membrane supply water tank 23). As described above, the desalting unit 30 is sterilized. Since raw water is sent without containing any components (bactericidal agents having bactericidal power), a biofilm is formed by these microorganisms.

  Of these, for example, with respect to scales, fouling can be suppressed even when the concentration of the electrolyte contained in the water to be treated is high by injecting a scale inhibitor or a pH adjuster to adjust the conditions so that the scales are difficult to precipitate. It becomes possible. In the case of scale and biofouling, it is possible to remove adsorbates such as electrolytes and microorganisms by shearing force by periodically flowing clean water over the surface of the RO membrane.

  On the other hand, in the case of organic matter fouling, the size of the organic matter (deposition thickness) is significantly smaller than the thickness of the boundary layer with the flowing water surface (treated water flow surface) on the RO membrane surface, so it is adsorbed on the surface. It is difficult to completely remove the organic matter with shearing force.

  For example, in the case of the seawater desalination system 1, there are variations depending on the configuration and performance of the pretreatment unit 20, the quality of seawater, and the type of chemicals injected in the chemical injection system 24, but TOC (Total Organic Carbon) In terms of amount), about 0.1 to 10 mg / L of organic matter is contained in the raw water sent to the desalting unit 30. Such organic matter gradually accumulates on the surface of the RO membrane, so that the water permeation performance is hindered (organic matter fouling), and the amount of permeated water decreases when operating at a constant pressure. On the other hand, when feedback is applied to power (for example, pressure) in order to obtain a constant amount of permeated water, the operating pressure increases. In either case, the power cost of the pump per unit permeate increases. On the other hand, when the RO membrane is chemically cleaned with a cleaning solution in order to remove organic fouling, the RO membrane is gradually deteriorated and the ion rejection rate is lowered.

  Further, when organic matter fouling progresses, the RO membrane filtration capability is remarkably lowered, and the RO membrane module 32 needs to be replaced. Since the seawater desalination system 1 is stopped for a long time when the RO membrane module 32 is replaced, the operation rate of the seawater desalination system 1 is lowered. In addition, since RO membrane cannot be recycled, it is necessary to finally replace it with a new RO membrane module. When the RO membrane module is replaced, its replacement part cost (consumables cost), replacement work cost, waste disposal cost, etc. are added to the running cost. For this reason, it becomes a cause which the running cost per unit permeated water amount increases further.

  In the present embodiment, as described above, the porous ceramic honeycomb adsorbent 22 is provided in the pretreatment unit 20 in the previous stage of the desalination unit 30, and the raw water is supplied before the raw water is supplied to the RO membrane module 32. By performing a pretreatment process in which the organic matter contained in the porous ceramic honeycomb adsorbent 22 is removed in advance, fouling of the organic matter on the surface of the RO membrane module 32 can be prevented, and the replacement life of the RO membrane module 32 can be extended. .

  In addition, as described above, as a pretreatment method, in addition to a method of adsorbing and collecting organic substances on an adsorbent installed in a water treatment line, a method of decomposing organic substances in raw water, or adding a flocculant Then, there is a method of collecting and removing organic substances as coarse particles. As a result of investigations by the inventors, among the methods described above, as a method of removing organic substances contained in seawater, a method of adsorbing and collecting organic substances on an adsorbent (for example, a porous ceramic honeycomb adsorbent), It has been confirmed that it is most effective.

  On the other hand, when the water treatment operation is continued for a long time, the adsorbate such as organic matter gradually accumulates in the porous ceramic honeycomb adsorbent 22 used in the pretreatment process, and traps the organic matter contained in the seawater. The performance, that is, the removal rate gradually decreases. As the accumulation of adsorbate further progresses, as with RO membranes, the operating rate of the water treatment system decreases due to the replacement of the adsorbent, and the running cost per unit permeate due to the increase in the cost of consumables for adsorbent and the increase in waste disposal costs. The increase of the problem becomes a problem.

  For this reason, after performing a water treatment such as seawater treatment for a certain period of time, an adsorbate such as an organic substance adsorbed on the porous ceramic honeycomb adsorbent 22 is removed to recover the adsorption performance of the porous ceramic honeycomb adsorbent. Do.

Next, the removal processing of the adsorbate of the porous ceramic honeycomb adsorbent will be described.
In the removal process of the adsorbate adhering to the porous ceramic honeycomb adsorbent 22, first, the pressure release valve VL6 is opened, and the opening degree of the adjustment valve VL7 is appropriately adjusted to be held by the porous ceramic honeycomb adsorbent 22. The treated water is discharged. The treated water held in the porous ceramic honeycomb adsorbent 22 is drained from the valve VL7, stored in a separate drainage tank 25c, and supplied again to the porous ceramic honeycomb adsorbent 22 by the pump 25d. Also good.

  After moisture is removed from the porous ceramic honeycomb adsorbent 22, the control valve VL5 is adjusted to an appropriate opening degree, and ozone gas is supplied from the ozone generator 25a to the porous ceramic honeycomb adsorbent 22. The adsorbate adsorbed on the porous ceramic honeycomb adsorbent 22 is decomposed and removed by ozone gas. After treating the adsorbate, the ozone gas that has passed through the porous ceramic honeycomb adsorbent 22 is rendered harmless by the ozone detoxifying device 25b and exhausted from the valve VL8. When the pressure release valve VL6 also serves as an exhaust valve of the ozone detoxifying device 25b, the detoxified gas is exhausted from the valve VL6.

  As described above, the step of removing deposits such as organic substances adsorbed on the porous ceramic honeycomb adsorbent 22 is performed at regular intervals. Thereby, the replacement life of the porous ceramic honeycomb adsorbent 22 is extended, and an efficient water treatment can be performed at a low cost.

  The ventilation of the ozone gas to the porous ceramic honeycomb adsorbent 22 is usually performed at room temperature. Since the adsorbate removal process can be performed at room temperature, energy saving can be achieved. The ventilation of ozone gas can be performed at a temperature suitable for each condition depending on the object to be treated, the environment of the water treatment line, and the like.

The flow rate of the ozone gas when the ozone gas is passed through the porous ceramic honeycomb adsorbent 22 is not particularly limited, but an example of the inventors' estimation is shown below.
A trial calculation example per one porous ceramic honeycomb adsorbent having a 1-inch filter and an adsorption area of 1.03 m ² = 1.03 × 10 ⁴ cm ² is shown. In order to efficiently remove the adsorbate by the ventilation of ozone gas, it is desirable that the flow rate of ozone gas be large according to the area.

From the viewpoint of increasing the organic substance removal efficiency, an example of the flow rate of ozone gas is 5 to 500 mL / min. Moreover, an example of the ozone gas flow rate per unit adsorption area of the porous ceramic honeycomb adsorbent is 5 × 10 ⁻⁴ mL to 0.05 mL / min · cm ² .

Next, the structure of the adsorption module will be described.
The structure of the porous ceramic honeycomb adsorbent used in the present embodiment and the structure of the adsorption module having the porous ceramic honeycomb adsorbent will be described with reference to FIGS. FIG. 4 is a cross-sectional view showing an example of an adsorption module having a porous ceramic honeycomb adsorbent.

  As shown in FIG. 4, the adsorption module M includes a porous ceramic honeycomb adsorbent 22, a housing (resinous storage container) 201 and an adsorbent support 202, and the porous ceramic honeycomb adsorbent 22 includes an O-ring 203. It is accommodated by the adsorbent support 202 in the housing 201.

  The adsorbent support 202 is fixed to one end into which pre-treatment water flows and the other end through which post-treatment water flows out. An O-ring 203 is provided between the adsorbent support 202 and the porous ceramic honeycomb adsorbent 22, and the water passed through the adsorption module M is passed through the O-ring 203 by the porous ceramic honeycomb adsorbent 22. Water is induced inside the honeycomb without going around the outside.

  FIG. 5 is an end view on the inflow side showing an example of the porous ceramic honeycomb adsorbent, and FIGS. 5 (a) and 5 (b) each have a quadrangular cross section in the direction perpendicular to the direction in which water flows. It is an end view in the case where the cross section of the flow path in the direction orthogonal to the end view and the direction in which water flows is a triangle. The direction in which water flows refers to the direction from the inlet to the outlet on the inflow side of the porous ceramic honeycomb adsorbent. The orthogonal direction means an angle formed substantially perpendicular to the direction in which water flows, and does not indicate only 90 degrees. Here, the end surface refers to a contact surface with the O-ring 203 of the porous ceramic honeycomb adsorbent 22, facing a direction in which the treated water flows, and a first surface into which water before treatment flows, and after treatment And a second surface from which the water flows out. 5A shows a channel having a square cross section, and FIG. 5B shows a channel having a regular triangle cross section, but the present invention is not limited to this. For example, it may be a rectangle or an isosceles triangle.

  5A and 5B, the porous ceramic honeycomb adsorbent 22 includes an outer peripheral wall 209, a plurality of channels 212 provided inside the outer peripheral wall 209, and adjacent channels 212. And a partition wall 210 to be spaced apart from each other.

  The plurality of flow paths 212 are arranged side by side in the first direction and the second direction that are not parallel to each other on the end surface, and the through holes that penetrate from the inflow side surface to the outflow side surface are connected to the inflow side end surface or It is formed by plugging the end face on the outflow side. Specifically, the first flow path 212a in which the inflow side of water before treatment is opened and the outflow side of water after treatment on the opposite side is plugged by the plugging portion 211, and the outflow of water after treatment The second flow path 212b is opened on the side, and the inflow side of the water before treatment on the opposite side is plugged with the plugging portion 211. The first channel 212a and the second channel 212b are alternately arranged in the first direction and the second direction, respectively. The length of one side of the cross section of the channel 212 is, for example, about 0.5 to 5 mm.

  The communication hole formed in the partition wall 210 is configured with an average pore diameter (for example, about 20 μm) that is a hole structure thinner than the diameter of the flow path 212, and between adjacent flow paths 212 (for example, the first flow path 212 a). And a plurality of communication holes (not shown) are formed.

  FIG. 6 is a cross-sectional view of the porous ceramic honeycomb adsorbent along the direction of water flow. As shown in FIG. 6, the pre-treatment water flows into the porous ceramic honeycomb adsorbent 22 into the first flow path 212 a that is open on the inflow side. The pre-treatment water that has flowed into the first flow path 212a flows through a large number of communication holes formed in the partition wall 210 to the second flow path 212b adjacent to the first flow path 212a. When water passes through the surface of the partition wall 210 or the inner surface of the communication hole formed in the partition wall 210, the organic matter contained in the water is adsorbed and removed. Thereafter, the water that has flowed into the second flow path 212b flows out from the opened outflow side of the second flow path 212b.

  Since the porous ceramic honeycomb adsorbent 22 has the above-described structure, the water retained in the adsorbent is easily discharged, and the pressure release valve VL6 and the adjustment valve VL7 installed at both ends thereof open and close to The water retained in the water can be discharged efficiently.

Next, the function of the porous ceramic honeycomb adsorbent will be described.
For example, in seawater desalination treatment, among organic substances dissolved in seawater, it is mainly polysaccharides that are selectively adsorbed to the RO membrane, and acidic polysaccharides among the polysaccharides are negatively charged, Saccharides are water-soluble substances and have many hydroxyl groups.

  On the other hand, the surface of an aqueous solution of a metal oxide such as alumina is positively charged when the pH of the aqueous solution is lower than its isoelectric point, and conversely when the pH of the aqueous solution is higher than its isoelectric point. Negatively charged. For example, since the isoelectric point of alumina is usually around pH = 9, the alumina surface in a neutral aqueous solution is positively charged, and the alumina surface in an alkaline aqueous solution at pH = 10 is negatively charged. Moreover, many oxygen atoms exist on metal oxides, such as an alumina, and these oxygen atoms form a hydrogen bond with the hydroxyl group which a water-soluble substance has. For this reason, a water-soluble substance is adsorbed on the metal oxide.

  For this reason, the supplementary performance of organic matter can be further improved by coating the surface of the ceramic filter on the solution introduction side with a metal oxide. Note that the metal oxide is originally derived from a metal but has already been oxidized, and thus has resistance to ozone gas.

(Experimental example 1)
In order to investigate the optimum surface material of the porous ceramic honeycomb adsorbent, the following investigation was conducted. That is, the amount of hyaluronic acid adsorbed as an example of a natural organic substance contained in seawater was compared using a metal oxide powder that can be a surface material of a porous ceramic honeycomb adsorbent.

  Five types of metal oxides were used. As a result of preparing and measuring samples with cordierite, α-alumina, γ-alumina, titanium oxide, and zinc oxide, the amount of hyaluronic acid adsorbed per surface area of the surface material was about 10 times that of cordierite. It was about 3 times larger than that of titanium oxide and zinc oxide. Further, γ-alumina gave the same results as α-alumina.

  In view of the above, the porous ceramic honeycomb adsorbent in which at least the surfaces of the partition walls are made of alumina is suitable for removing substances that are easily adsorbed on the RO membrane, that is, polysaccharides, from raw water. In other words, the porous ceramic honeycomb adsorbent 22 only needs to have the partition wall 210 as an adsorbing portion made of ceramic, but at least the surface of the partition wall 210 is preferably formed of alumina. The partition wall 210 of the porous ceramic honeycomb adsorbent 22 may be formed of alumina on a ceramic such as cordierite other than alumina, for example, and the entire partition wall 210 is formed of alumina. There may be. At this time, the alumina may be α-alumina or γ-alumina.

  Based on the above results, in this example, ceramic whose surface is alumina was used as the adsorbent. Of course, the case where the surface is other than alumina is not excluded.

(Experimental example 2)
Specific experimental results will be described for the adsorption removal of organic substances (hereinafter referred to as natural organic substances) contained in seawater by the porous ceramic honeycomb adsorbent.

  As a result of the examination by the inventors, it was confirmed that the porous ceramic honeycomb adsorbent 22 having the surface of the partition wall 210 coated with alumina has a characteristic of capturing natural organic matter in seawater. Specifically, the porous ceramic honeycomb adsorbent 22 was obtained by coating alumina (γ-alumina) on partition walls 210 made of cordierite. The slurry containing alumina was sucked and supplied into the porous ceramic honeycomb adsorbent, and then dried and fired. The thickness of alumina converted from the coating amount of alumina is 1 μm or less.

  Further, as the porous ceramic honeycomb adsorbent 22, when the surface material of the partition wall 210 is cordierite, which is a kind of ceramic, and the surface material of the partition wall 210 is alumina, trapping of organic substances contained in seawater The performance was compared. For example, when seawater collected at Yokohama Port is passed through the porous ceramic honeycomb adsorbent 22 at a space velocity of 120 (1 / h), and the surface material is cordierite, natural organic matter contained in the seawater When the surface material was alumina, the removal rate of natural organic substances contained in seawater was 10 to 60%. That is, it was confirmed that a porous ceramic honeycomb adsorbent in which the surface material of the partition wall 210 is alumina is more suitable for capturing natural organic matter in seawater.

(Experimental example 3)
Next, evaluation of adsorption and removal of natural organic substances on the porous ceramic honeycomb adsorbent was performed. The experimental method will be described below.

  First, a porous ceramic honeycomb adsorbent was prepared. The average pore diameter of the porous ceramic honeycomb adsorbent is not particularly limited. Generally, the smaller the average pore diameter, the larger the surface area (specific surface area) per unit volume, and the smaller the adsorption capacity. The average pore diameter is desirable. On the other hand, according to the Hagen-Poiseuille equation, the smaller the average pore diameter, the greater the permeation resistance. Therefore, power is required to pass water through the porous ceramic honeycomb adsorbent. In addition, the smaller the average pore diameter, the more likely the blockage occurs due to fine suspended components. Therefore, the optimum average pore diameter for the porous ceramic honeycomb adsorbent is about 1 μm to 50 μm.

In addition, the average pore diameter in the present invention is a pore diameter corresponding to 50% of the total pore volume in the pore diameter distribution.
The average pore diameter of the partition walls can be measured using, for example, a mercury intrusion porosimeter. Mercury intrusion porosimeters inject mercury into a vacuum septum sample and determine the relationship between the indentation pressure and the volume of mercury injected into the pores of the septum sample. This is a method for obtaining the relationship (pore size distribution).

  The present inventors mainly used a porous ceramic honeycomb adsorbent having a partition wall thickness of 0.3 mm and an average pore diameter of 20 μm, a partition wall thickness of 1 mm and an average pore diameter of 10 μm, and the like. It was used to test the passage of seawater.

  Specifically, when the seawater was passed through the porous ceramic honeycomb adsorbent at a space velocity of 120 (1 / h) and the differential pressure generated at that time was measured, in any porous ceramic honeycomb adsorbent, The maximum differential pressure was 4 kPa, which was confirmed to be sufficiently small compared to the capacity of a normal water pump. That is, it was confirmed that if the thickness of the partition wall 210 is 50 μm or more, the destruction due to pressure is avoided.

  In addition, the thicker the partition wall 210, the longer the time required for the solution to be treated to pass through the inside of the wall, and the specific surface area increases. However, if the wall thickness is too large, the adsorption area is reduced and the adsorption performance is degraded. Appropriate design will be performed after taking these into consideration.

  An average pore diameter of 1 μm or more is suitable as a porous ceramic honeycomb adsorbent.

(Experimental example 4)
Subsequently, an aqueous solution containing a typical natural organic substance contained in seawater was prepared as an experimental treatment target solution for the treatment of adsorbate. As a typical natural organic substance, an aqueous solution of mannan (a kind of polysaccharide, a substance in which monosaccharide mannose is polymerized by glycosidic bonds), which is easily adsorbed on RO membranes and is considered to cause organic fouling and biofouling. Was used in the following study. The concentration of mannan was 6 mg / L. At this time, artificial seawater was used as an aqueous solution for dissolving mannan. Artificial seawater contains NaCl and other average electrolytes contained in normal seawater, but unlike natural seawater, it does not contain natural organic matter. Artificial seawater was prepared so that the concentration of NaCl was 3.5%.

  The removal rate of mannan in the mannan solution is determined by the TOC value of the mannan solution before and after water passage when the mannan solution is passed through the porous ceramic honeycomb adsorbent for a certain time (Total Organic Carbon: Total organic carbon amount [mg / L ]) Was measured using a total organic carbon meter, and the removal rate of mannan in the solution was calculated by the following (formula 1).

Removal rate = (TOC value of the solution before passing through the adsorbent-TOC value of the solution after passing) / TOC value of the solution before passing (Formula 1)
However, since the evaluation using the porous ceramic honeycomb adsorbent takes time, more appropriate design evaluation can be performed if it can be evaluated by a simpler method. Therefore, in this experiment, measurement was performed by the QCM method.
As will be described later, the inventors have found that measurement with high reproducibility is possible even by the QCM method, and the corresponding relationship will be described later.

In this experiment, the relationship between the cleaning method and the cleaning performance of the adsorbate was examined. The experimental results are shown in FIG.
Here, the definition of the recovery rate is shown. The recovery rate is the ratio B / A of the mannan adsorption amount before and after cleaning, where A is the adsorption amount before cleaning and B is the adsorption amount after cleaning. At this time, B / A is defined as a recovery rate of the adsorption performance by washing (recovery rate = 1 is total recovery). That is, the higher the recovery rate, the higher the cleaning performance. After sufficient mannan was adhered to the surface of the measurement sample of the QCM method, the measurement sample was washed by six types of washing methods. The recovery rate by cleaning the adsorbate is shown for each cleaning method.

In FIG. 11, 1 is the result of cleaning with ozone gas for 10 minutes, 2 is the result of cleaning with ozone-dissolved water (in dilute acetic acid), 3 is the result of cleaning with dilute acetic acid as a reference, and 4 is sodium persulfate (Na ₂ S). _The result of washing with a ₂ O ₈ ) aqueous solution, 5 the result of washing with aqueous hydrogen peroxide, and 6 the result of washing with an aqueous solution using sodium hydroxide (NaOH) as a strong alkali solution with pH = 13. In addition, although a cleaning experiment using a commercially available surfactant was also performed, the cleaning effect superior to that of the reference was not obtained, so the description is omitted.

  As can be seen from FIG. 11, it became clear that the cleaning ability with ozone gas in a gaseous state can achieve an overwhelming recovery rate compared to other cleaning methods. At the same time, it became clear that the cleaning effect of ozone-dissolved water was limited.

  FIG. 12 shows the evaluation of cleaning ability with ozone gas and ozone cleaning water over time. The recovery rate of black circles with ozone gas increases with time. On the other hand, the recovery rate by the black square ozone cleaning water does not improve even if time passes. When compared at the time of the treatment time of 30 minutes, the recovery rate by the ozone gas reaches 20 times or more the recovery rate by the ozone cleaning water, and the difference is considered to further increase with time.

  As described above, the experiments by the inventors have revealed that cleaning of the adsorbent with gaseous ozone gas has overwhelming performance.

<Details of experiment>
A detailed experimental method for the reproduction experiment is described below.
The cleaning methods are classified into the following three types according to the concept of cleaning. That is, (1) a method of oxidizing and decomposing an adsorbate with a cleaning component having a high oxidizing power, (2) a method of dissolving an alumina surface layer, and (3) peeling off a surface layer adsorbent using the permeation action of a surfactant. How to do.

(1) Method to oxidize and decompose adsorbate with cleaning component having high oxidizing power
In this classification, hydrogen peroxide solution (H ₂ O ₂ ), sodium persulfate (Na ₂ S ₂ O ₈ ) aqueous solution, ozone-dissolved water (O ₃ -dissolved water, ozone dissolution concentration: 0.2 to 0.4 mmol / L, in 10 mmol / L dilute acetic acid) and ozone gas (O ₃ gas, ozone gas concentration: 2.1 mmol / L).

  The hydrogen peroxide solution includes a hydrogen peroxide solution (concentration 30%) and a sodium hydroxide (NaOH) aqueous solution (concentration 1 mmol / L) so that the hydrogen peroxide concentration is 0.5 mol / L and the pH is about 8-9. L, pH = 11). The pH of the hydrogen peroxide solution after adjustment was pH = 8.6. In addition, the sodium persulfate aqueous solution had a sodium persulfate concentration of 0.5 mol / L and a pH of about 2-3, and sodium persulfate and a sodium hydroxide (NaOH) aqueous solution (concentration 1 mmol / L, pH = 11). The pH of the aqueous sodium persulfate solution after adjustment was pH = 2.1.

  In preparing ozone-dissolved water, considering the fact that the decomposition rate of ozone in water is faster as the pH value is larger (alkaline side), a diluted pH of about 3 is used to suppress decomposition of ozone in the liquid phase. Ozone gas was introduced into acetic acid (10 mmol / L acetic acid (AcOH) aqueous solution) for about 2 hours. Moreover, the commercially available electrolytic ozone generator was used for ozone gas and ozone solution water preparation.

  When the ozone gas generator is used, the flow rate of air containing ozone gas is about 170 mL / min, and ozone gas flows about 9 mL / min from the ozone generation conditions.

FIG. 10 shows an experimental system for cleaning with ozone gas.
When the QCM sensor 41 of the QCM method after the mannan adsorption is washed with ozone gas, the sample water in the cell 42 is removed in advance, and the QCM sensor 41 is removed from the QCM apparatus 4 shown in FIG. Next, ozone gas 52 was introduced from the ozone generator 50 through the PFA tube 51. The ozone gas 52 discharge port of the PFA tube 51 reaches the bottom of the PP beaker 53 and the PFA beaker 54 in the PP beaker 53 and is introduced to the QCM sensor 41 installed in the PFA beaker 54. The QCM sensor 41 was held vertically by a sensor holder 55 made of a dedicated highly corrosive material. The PP beaker 53 was covered with a highly corrosion-resistant sheet 56 from above the mouth, and the atmosphere inside the PP beaker 53 and the PFA beaker 54 was maintained. In this experimental system, the ozone gas 52 was vented over a predetermined time to clean the QCM sensor 41.

(2) Method for Dissolving Alumina Surface Layer In this classification, the adsorbate adsorbed on the surface layer falls off and is removed by dissolving the alumina on the surface of the QCM sensor in the QCM method. A sodium hydroxide (NaOH) aqueous solution (concentration 0.1 mol / L, pH = 13) was used as the solution.

(3) Method of peeling surface layer adsorbate using the permeation action of surfactant
This classification is a method of cleaning using the action of a surfactant, but since the adsorbed substances could not be removed significantly with a commercially available cleaning material, the explanation is omitted.

  After the above-described adsorption amount A was evaluated, the mannan adsorption amount B was evaluated again using the QCM sensor 41 after the above cleaning process. The QCM sensor 41 after cleaning was again attached to the QCM apparatus, and an adsorption experiment using mannan was performed in the same manner as the adsorption experiment performed before cleaning.

  Here, the ratio B / A of the mannan adsorption amount before and after cleaning is defined as the recovery rate of the adsorption performance of alumina on the sensor by the cleaning (recovery rate = 1 is the total recovery). That is, the higher the recovery rate, the higher the cleaning performance. FIG. 11 shows a cleaning evaluation result obtained by evaluating each recovery rate when each of the above-described cleaning solutions or cleaning gases is used.

  From FIG. 11, the cleaning treatment with the solution (all treatment for 10 minutes), that is, the cleaning treatment using the hydrogen peroxide solution, the sodium persulfate aqueous solution, the ozone-dissolved water, and the sodium hydroxide aqueous solution all have a recovery rate of 0.05 to The cleaning performance of the adsorbate was low.

  However, the recovery rate was as high as 0.65, only when ozone gas was passed. In particular, in ozone-dissolved water and ozone gas, the treatment time was the same 10 minutes, although the ozone was used as a cleaning component, and there was a difference of about 10 times in the recovery rate.

  Furthermore, the result of having compared the processing time dependence of each recovery rate when ozone-dissolved water and ozone gas are used for the washing | cleaning after adsorption processing is shown in FIG. It is the graph which compared the processing time dependence of each adsorption performance recovery rate when ozone dissolved water and ozone gas are used for the washing | cleaning after adsorption processing.

  From FIG. 12, with ozone gas, the recovery rate increased with the treatment time, and after 30 minutes of treatment, the recovery rate was 0.84. On the other hand, in ozone-dissolved water, the recovery rate is only 0.04 when the treatment time is 30 minutes and 60 minutes, there is no increase in the recovery rate with the treatment time, and the cleaning effect is improved. There wasn't. Although not shown in the graph, even with dilute acetic acid alone in which ozone was not dissolved, the recovery rate was 0.04 after a treatment time of 60 minutes. From this, it can be seen that there was almost no cleaning effect due to dissolved ozone.

  The mechanism of mannan removal by ozone gas is considered as follows. That is, it is considered that the adsorbed substance (mannan in this experimental example) adsorbed on alumina on the QCM sensor 41 was decomposed by ozone gas and diffused into the gas phase. As another mechanism, the adsorbed substance comes into a substance that is easily dissolved in water when it comes into contact with ozone gas, and the cell 42 (see FIG. 7) is again filled with the treated water and the treated water is brought into contact with the surface of the QCM sensor 41. When dissolved, it is considered that it was dissolved in the liquid phase.

Next, what causes the difference in recovery rate between ozone-dissolved water and ozone gas will be discussed below.
In general, an ozone water generator or an injector (also called an ejector or ejector) is provided with a bottleneck in part of the liquid flow path, and the flow rate of that part is increased to draw ozone gas in a reduced pressure state from the ozone generator. Even if ozone gas is dissolved in water (neutral) through a device), ozone gas dissolved in water is about 5% of the amount of ozone generated from the ozone generator, and the remaining ozone gas is said to be almost diffused into the atmosphere. It has been broken. Since the maximum amount of ozone generated by the ozone generator used in this example is 200 g / m ³ (about 4.2 mmol / L), about 5% thereof, that is, about 10 g / m ³ (about 0.2 mmol / L). ) Ozone gas is considered dissolved in water. As described in the examples, the amount of ozone dissolved increases on the acidic side.

  That is, under the same output conditions using the same ozone generator, the concentration of ozone itself can be about 10 to 20 times higher in the gas phase than in the liquid phase. It can be said that the removal reaction proceeds. In this example, it is considered that the reason why the ozone gas was used was about 20 times larger at the maximum when the ozone gas was used than when the ozone dissolved water was used. On the other hand, in the ozone-dissolved water, if the ozone-dissolved concentration is to be increased, the output of the ozone generator needs to be increased by 10 to 20 times, which is not rational from an economical viewpoint.

  Therefore, the superiority of the present invention in which the organic substance treatment with ozone gas is performed is clear.

  In this example, a procedure for replacing a porous ceramic honeycomb adsorbent as an adsorbent will be described.

  The water treatment system has a calculation unit, and the calculation by this calculation unit compares the processing capacity at the start of operation of the adsorption module with the processing capacity at the time of measurement, and the processing capacity is lower than at the start of operation. Is confirmed or determined. That is, the usage time of the adsorption module is measured.

  When the water treatment performance of the adsorption module is lower than that at the beginning of operation, for example, it is displayed on the display unit provided in the water treatment system so as to be replaced. In addition, the determination result may be notified to an administrator of the water treatment system or a service maker performing maintenance by e-mail or the like so as to replace the adsorption module. In this case, it is possible to know the replacement time of the adsorption module (time when replacement is recommended) from other than the water treatment system.

  The replacement timing of the adsorption module is managed by, for example, a calculation unit provided in the water treatment system, and an appropriate replacement time may be notified to the user from the calculation unit. Further, the replacement timing of the adsorption module is managed by, for example, a porous ceramic honeycomb adsorbent maker, and an appropriate replacement time may be notified from the porous ceramic honeycomb adsorbent maker to the user.

  In the calculation of the replacement time, the time from the start of operation of the previously used adsorption module to the replacement, that is, the usage time is stored. Also, measure the operation time of the adsorption module currently in use, determine the difference from the replacement time of the adsorption module used earlier, calculate the recommended time until replacement, and obtain appropriate water treatment performance. You may notify the remaining time of the useful life of the state to be prepared. Appropriate water treatment performance is appropriately set depending on the water treatment system used. Moreover, you may obtain | require and notify the replacement frequency corresponding to the water treatment system by measuring and memorize | storing the replacement | exchange period of an adsorption | suction module. In this case, it is possible to propose a more suitable replacement time based not only on the performance deterioration of the adsorption module itself but also on the relationship with the treated water from the relationship between the treated water to be treated by the water treatment system and the durability performance of the adsorption module. it can.

  In addition to these notification methods, the above-described notification method by the user, the system administrator, or mail may be used. In this case, the replacement time can be notified in advance before the processing capacity of the adsorption module decreases. Therefore, it is useful for making a maintenance plan for the entire water treatment system together with maintenance of other configurations.

  In addition, a plurality of notification methods may be provided. For example, not only the manager of the water treatment system, but also the manufacturer who sells or supplies the adsorption module is notified in advance of the replacement time of the adsorption module. I can inform you. In this case, when the user of the water treatment system desires to replace the adsorption module having a reduced processing capacity, the manufacturer can already prepare an adsorption module for replacement corresponding to the water treatment system in advance.

These notification methods can be similarly applied to other embodiments, and it is desirable to implement them in consideration of efficient operation of the water treatment system.
In addition, these notification methods are not essential components, but are an example of an embodiment of a water treatment system.

  Further, in the notification described above, when the performance of the adsorption module is recovered not only by replacement of the adsorption module but also by cleaning, the cleaning time (time when cleaning is recommended) may be notified. . In this case, it can be used for a long time by washing the adsorption module.

  Further, the cleaning frequency and the replacement frequency may be notified together, and in this case, it is possible to contribute to the extension of the life of the adsorption module by the cleaning, the appropriate proposal of the replacement time, and the preparation of the maintenance plan. In addition, it is possible to prevent a reduction in water treatment performance of the water treatment system as a whole.

  Further, the cleaning frequency and the replacement frequency can be obtained statistically or empirically with reference to each measured information.

  The adsorption modules M shown in FIG. 4 can be arranged in parallel and in series as necessary, and valves for water passage are provided at the inlet and outlet of each adsorption module M (not shown). Furthermore, a pressure release valve VL6 and an adjustment valve VL7 for adjusting the amount of drainage are provided at the inlet or outlet of each adsorption module M (not shown). When replacing the adsorption module M, the inlet and outlet valves for the adsorption module M to be replaced are closed, and then the pressure release valve VL6 and the adjustment valve VL7 for adjusting the amount of drainage are opened to open the housing 201. It is possible to take out the porous ceramic honeycomb adsorbent 22 from the housing 201 by releasing the pressure and discharging the treated water therein. Thereafter, a new porous ceramic honeycomb adsorbent 22 is loaded into the housing 201, the housing 201 is assembled, the pressure release valve VL6 of the adsorption module M and the adjustment valve VL7 for adjusting the amount of drainage are closed, and then the outlet side of the adsorption module M Open the valve and the inlet-side water valve and start water flow.

  Thus, the porous ceramic honeycomb adsorbent according to the present example can maintain the permeation performance over a long period of time by performing an appropriate cleaning process and replacement process.

  It is also possible to use the porous ceramic honeycomb adsorbent for seawater desalination immediately after removing the natural organic matter adsorbed by the ozone gas treatment described above.

  According to the present embodiment, in the pretreatment section, organic substances that cause deterioration of the performance of the RO membrane can be selectively removed from the raw water in advance by the porous ceramic honeycomb adsorbent, and further, the porous ceramic honeycomb adsorption The organic substance adsorbed on the material can be efficiently removed by a cleaning process using ozone gas, and the porous ceramic honeycomb adsorbent can be regenerated. Thereby, the replacement frequency of the RO membrane module and the replacement frequency of the porous ceramic honeycomb adsorbent are reduced, and the running cost of the seawater desalination system can be reduced. For this reason, the water treatment cost of a water treatment system can be reduced.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  In the above embodiment, when it is necessary for the sake of convenience, the description has been divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other, and one is the other. There are some or all of the modifications, details, supplementary explanations, and the like. Further, in the above embodiment, when the number of elements (including the number, numerical value, quantity, range, etc.) is mentioned, particularly when clearly indicated and when it is clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

  In addition, the findings found in the above experimental examples are included in the scope of the present invention as long as they are significantly superior, and are combined with the respective examples.

(Example of verification experiment)
This section explains that the cleaning performance can be evaluated by the QCM method for a reproduction experiment. In the QCM method, a sensor (hereinafter abbreviated as a sensor) formed on a crystal resonator is utilized by utilizing a phenomenon in which the resonance frequency changes in proportion to the weight change when molecules adhere to the surface of the crystal resonator and vibrate. Measure the minute weight of the top deposit.

  The QCM method has been used to measure the film thickness of a vacuum film forming apparatus in the field of semiconductor manufacturing and the like. On the other hand, since it is difficult to oscillate the vibrator in liquid, the measurement by the QCM method has been limited to use in vacuum or in air. It has come to be used in fields such as bioscience and material development.

  In the following evaluation of adsorption performance and removal performance, a commercially available QCM apparatus capable of measuring a minute mass change in a liquid was used, and this preliminary examination was performed using this apparatus. In this preliminary study, alumina equivalent to the surface of the porous ceramic honeycomb adsorbent was formed on the surface of the sensor, and this alumina was used as the adsorption surface. Hereinafter, after first explaining the measurement principle of the QCM method and the outline of the QCM apparatus, it will be described that the adsorption phenomenon in the porous ceramic honeycomb adsorbent can be easily reproduced by the QCM method.

First, the measurement principle of the QCM apparatus and the outline of the apparatus will be described. In the QCM method, distortion vibration is applied to a crystal resonator, and the resonance frequency (f) at that time is measured. The resonance frequency (f) decreases in accordance with the Sauerbrey equation shown in the following (Equation 2) with a change amount approximately proportional to the increase in the weight of the deposit on the sensor due to adsorption to the sensor surface.
Δf / n = −CΔm (Formula 2)
Here, Δf is a change amount [Hz] of the resonance frequency, n is an n-fold wave when oscillating with an overtone, and Δm is a weight change amount per unit area. The value of C in (Expression 2) is obtained from the initial resonance frequency f ₀ of the sensor, the density ρ _{q of} the crystal, and the shear stress μq.

In the QCM apparatus used in this study, f ₀ is 4.96 MHz, ρ _q is 2648 kg / m ³ , and μq is 2.947 kg / m · s. Therefore, (Equation 3) is derived from these constants.
Δm = −17.9 (Δf / n) [ng / cm ² ] (Formula 3)
The sensitivity of the present QCM device is 0.1 Hz, that is, 1.79 ng / cm ² when n = 1.

FIG. 7 shows a schematic configuration of the QCM apparatus.
The QCM device 4 includes a QCM sensor 41, a cell 42, a flow path 43, a temperature control metal plate 44, a weight measuring unit 45, and a tube pump (not shown). Although there are several methods for supplying the sample water 47 to the QCM sensor 41 depending on the type of the QCM device, the QCM device 4 uses a flow type cell 42 as shown in FIG.

  In the QCM device 4 used in this preliminary study, the volume of the liquid contact portion between the cell 42 and the QCM sensor 41 is 0.04 mL, and the sample flow rate of the sample water 47 in the flow path 43 is 0.5 mL / min at the maximum. . The entire cell 42 is made of metal, but the wetted part is made of titanium having corrosion resistance and can be applied to the measurement of seawater. The cell 42 is installed on the metal plate 44. A Peltier element 48 for temperature control is embedded in the metal plate 44 and is controlled so that the temperature of the sample water 47 during measurement is kept at ± 0.02 ° C. or lower. In the weight measuring unit 45, the resonance frequency change and the weight change due to the adsorbed material 49 on the liquid contact part of the QCM sensor 41 are measured in real time.

  Hereinafter, the mannan adsorption mode for the alumina on the sensor surface in the QCM method is equivalent to the adsorption mode on the surface of the porous ceramic honeycomb adsorbent, and the adsorption phenomenon in the porous ceramic honeycomb adsorbent is reproduced on the sensor surface in the QCM method. To verify that.

Prepare 6mg / L aqueous solution of mannan (polysaccharide) described later, which is a natural organic substance in seawater as an adsorbent, and measure the mannan removal rate on the porous ceramic honeycomb adsorbent and on the sensor of the QCM device for comparison. did.
The experimental conditions are as follows.

(Adsorbent condition (both porous ceramic honeycomb adsorbent and QCM))
Adsorbed material: Mannan
Adsorbed substance concentration: 6mg / L
Adsorption time: 90min
(Experimental conditions for porous ceramic honeycomb adsorbent)
Adsorbent surface material: Alumina
Adsorbent diameter: 1 inch
Adsorbent length: 35mm
Flow rate: 40 mL / min (SV = 120 [/ h])
Adsorption area (surface area): 1.03 m ² = 1.03 × 10 ⁴ cm ²
Temperature: Room temperature
(Experimental conditions for QCM)
Adsorption surface material: Alumina
Adsorption area: 1.0 cm ²
Flow rate: 0.2mL / min
Temperature: 26.0 ° C
(Experimental result)
Under the above experimental conditions, first, the mannan removal rate of the porous ceramic honeycomb adsorbent was calculated for each time point after 10 minutes, 30 minutes, 60 minutes, and 90 minutes after the start time of water flow of the mannan aqueous solution.

  That is, the TOC of the mannan solution before passing water through the porous ceramic honeycomb adsorbent at each time point after 10 min, 30 min, 60 min, and 90 min after the start time of passing the aqueous solution of mannan into the porous ceramic honeycomb adsorbent, respectively. Value, and the TOC value of the mannan solution after passing water through the porous ceramic honeycomb adsorbent, respectively, were measured using a total organic carbon meter. From these measured values, after 10 minutes, based on the above (formula 1), The removal rate at each time point after 30 min, 60 min, and 90 min was calculated to be 34%, 17%, 8%, and 5%, respectively. The measurement results of the mannan removal rate of the porous ceramic honeycomb adsorbent are shown in black circles in FIG.

  Next, the removal rate when the mannan aqueous solution was passed through the QCM device 4 for 60 minutes was calculated by the QCM method, and compared with the removal rate of the porous ceramic honeycomb adsorbent. For comparison between the two, it is necessary to align the difference in adsorption conditions between the surface of the QCM sensor 41 (alumina) and the porous ceramic honeycomb adsorbent in the QCM method. For this reason, the removal rates were compared after first aligning the adsorption areas of the two, and then aligning the difference in flow rate between the two by fitting.

  Hereinafter, a detailed procedure will be described for comparison between the removal rate of mannan measured by the QCM method and the removal rate of mannan when water is passed through the porous ceramic honeycomb adsorbent.

First, the amount of adsorption in the QCM sensor 41 was determined from the above (Equation 3) from the measured value of the resonance frequency (f). FIG. 8 shows the change in the mannan adsorption amount on the QCM sensor 41 with respect to the adsorption time at this time. From the change in the adsorption amount shown in FIG. 8, it is confirmed that the adsorption amount has reached equilibrium within the measurement time, and the equilibrium adsorption amount is 0.44 μg / cm ² . Further, since the adsorption mode follows the Langmuir adsorption isotherm, the adsorption curve is expressed as the following (Formula 4).
W = We (1-exp (−Kt)) (Formula 4)
Here, W is an adsorption amount [μg / cm ² ] at an adsorption time t [min], We is an equilibrium adsorption amount, and K is a rate constant [min ⁻¹ ]. (Equation 4) can be further transformed as (Equation 5).

Ln (1-W / We) = − Kt (Formula 5)
The equilibrium adsorption amount We = 0.44 [μg / cm ² ] obtained from FIG. 8 and the obtained W value are substituted into (Equation 5), and the rate constant K = 0.5018 is obtained from fitting by an approximate expression. [Min ⁻¹ ] is obtained, and the adsorption formula in the QCM method is obtained (Formula 6).
Ln (1-W / 0.44) = − 0.5018t (Formula 6)

Next, an adsorption equation is obtained when the adsorption area of the QCM sensor is equal to the adsorption area of the porous ceramic honeycomb adsorbent. When the adsorption area of the QCM sensor is equivalent to the adsorption area of the porous ceramic honeycomb adsorbent, the equilibrium adsorption amount We on the surface of the QCM sensor is We = 0.44 μg / cm ^2. The equilibrium adsorption amount per one inch filter (surface area 1.03 m ² ) of the porous ceramic honeycomb adsorbent is 4.53 mg / filter. Thereby, (Formula 7) is obtained as an adsorption formula of QCM having an adsorption area equivalent to that of the porous ceramic honeycomb adsorbent.
Ln (1-W / 4.53) = − 0.5018t (Formula 7)

  Next, the removal rate by the QCM method when the flow rate by the QCM method is equivalent to that of the porous ceramic honeycomb adsorbent is obtained using the above (formula 7).

Removal rate = (W′−W) × 100 / (40 × 6 × 0.5) (Formula 8)
In the above (Formula 8), W ′ is the amount of adsorption after 30 seconds of W, and (40 × 6 × 0.5) is the amount of mannan [μg that passes over the wetted part of the QCM sensor in 30 seconds. ].

Further, based on the adsorption amount every 30 seconds from 0 seconds to 60 minutes after the adsorption time obtained from (Equation 7), the removal rate is continuously obtained using (Equation 8) to obtain a removal rate curve. .
Here, if the adsorption modes of the porous ceramic honeycomb adsorbent and the QCM sensor are the same, the removal rate curve agrees with the measurement result of the removal rate obtained with the porous ceramic honeycomb adsorbent. However, since the flow rate at the time of passing water to the QCM sensor 41 of the QCM device 4 and the flow rate at the time of passing water to the porous ceramic honeycomb adsorbent at the time of measuring the adsorption amount are different from each other, the rate constant in (Equation 7) ( K = 0.5018 [min ⁻¹ ]) is also different. Therefore, the rate constant K ′ [min ⁻¹ ] in the porous ceramic honeycomb adsorbent is expressed as K ′ = λK (λ is a correction coefficient).

  In FIG. 9, the removal rate curve obtained by (Equation 8) is shown by a thick solid line, and the removal rate curve of (Equation 8) is corrected by K ′ = λK, and the rate constant is corrected, respectively, by a broken line (λ = 0). 0.06), a chain line (λ = 0.03), and a solid line (λ = 0.045), and these were fitted to the measurement results of the removal rate of the porous ceramic honeycomb adsorbent (black circle plot).

From FIG. 9, it was confirmed that when λ = K ′ / K = 0.045 (solid line), the experimental results of the removal rate of the porous ceramic honeycomb adsorbent were almost the same. That is, it can be seen that K ′ = 0.023 [min ⁻¹ ], and the mannan adsorption mode for alumina on the sensor surface in the QCM method is equivalent to the adsorption mode on the surface (specific surface area) of the porous ceramic honeycomb adsorbent. It was confirmed that. In other words, it has been confirmed that the adsorption phenomenon in the porous ceramic honeycomb adsorbent is reproduced on the sensor surface in the QCM method.

  In addition, the evaluation of the natural organic matter adsorption performance and the removal performance when the adsorbate was washed using the QCM method was performed under the following conditions.

(Adsorbent conditions)
Adsorbed material: Mannan
Adsorbed substance concentration: 6mg / L
Adsorption time: 20min
(Cleaning conditions)
Cleaning substances: details below
Cleaning concentration: details below
Cleaning time: 10 min (however, ozone gas and ozone-dissolved water are listed separately)
(Experimental conditions for QCM)
Adsorption surface material: Alumina
Adsorption area: 1.0 cm ²
Flow rate: 0.2mL / min
Temperature: 26.0 ° C
An aqueous solution of mannan was passed through the QCM device, and the mannan was adsorbed on the alumina on the surface of the QCM sensor 41. The adsorption amount of the mannan solution after 20 minutes of adsorption time is calculated by (Equation 3) and is defined as adsorption amount A.

  After adsorbing the mannan, various cleaning solutions or cleaning gases are passed or passed through the QCM device 4 to clean and remove the mannan adsorbed on the alumina of the QCM sensor 41 formed on the crystal resonator. The cleaning ability can be evaluated by comparing.

DESCRIPTION OF SYMBOLS 1 ... Seawater desalination system, 10 ... Seawater intake part, 11 ... Intake pipe, 12 ... Intake pump, 13 ... Raw water tank, 20 ... Pretreatment part, 21 ... Sand filtration tank, 22 ... Porous ceramic honeycomb adsorbent, 201 DESCRIPTION OF SYMBOLS ... Housing (resin storage container), 202 ... Adsorbent support part, 203 ... O-ring, 209 ... Outer peripheral wall, 210 ... Partition wall, 211 ... Plugging part, 212 ... Channel, 212a ... First channel, 212b ... second flow path, 22a ... water pump, 23 ... RO membrane supply water tank, 24 ... chemical injection system, 24a ... sterilant injection part, 24b ... pH adjuster injection part, 24c ... flocculant injection part, 24d ... neutralization reducing agent injection part, 25 ... ozone supply system, 25a ... ozone generator, 25b ... ozone detoxification device, 25c ... drainage tank, 25d ... pump, 30 ... desalination part, 31 ... high pressure pump, 32 ... RO membrane model , 33 ... fresh water tank, 34 ... energy recovery device, 35 ... concentrated water tank, 36 ... waste water tank, 39 ... chemical injection system, 39a ... antibacterial agent injection part, 39b ... acid injection part, 39c ... alkali injection part, DESCRIPTION OF SYMBOLS 4 ... QCM apparatus, 41 ... QCM sensor, 42 ... Cell, 43 ... Flow path, 44 ... Metal plate for temperature control, 45 ... Weight measuring part, 47 ... Sample water, 48 ... Peltier element, 49 ... Adsorbed material, 50 ... Ozone generator, 51 ... PFA tube, 52 ... ozone gas, 53 ... PP beaker, 54 ... PFA beaker, 55 ... sensor holder, 56 ... high corrosion resistance sheet,
VL1 to VL5, VL9 to VL11 ... control valve, VL6 ... pressure release valve, VL7 ... control valve, VL8 ... exhaust valve, LM ... main line, LS ... sub line, M ... adsorption module, 100 ... pretreatment solution and its storage , 101 ... pump, 110 ... valve 1, 102 ... adsorption device, 103 ... filtration device, 130 ... waste solution, 140 ... solution after treatment, 150 ... solution to be treated, 151 ... hollow ceramic pipe, 152 ... treatment completed solution

Claims (24)

A solution processing system including an adsorption unit having an adsorption structure,
A solution processing system having a mechanism for supplying gaseous ozone gas to the adsorption structure.   The solution processing system according to claim 1, wherein the adsorption structure is made of ceramic.   The solution processing system according to claim 2, wherein the ceramic has a hollow structure, and a solution is supplied to the hollow structure portion.   The solution processing system according to claim 2, wherein the ceramic is porous.   The adsorption structure includes an outer wall, a plurality of flow paths provided on the inner side of the outer wall, and a partition wall that separates each of the plurality of flow paths from each other, and the partition wall communicates between adjacent flow paths. The solution processing system according to claim 2, wherein the solution processing system has a plurality of communicating holes to be formed and has a porous ceramic honeycomb structure in which an adsorption portion is formed by the partition walls.   The solution processing system according to claim 2, wherein a surface of the ceramic is alumina.   The solution processing system according to claim 2, wherein the ceramic has a honeycomb shape or a sponge shape.   The solution processing system according to any one of claims 1 to 5, further comprising a filtration unit having an RO membrane downstream of the adsorption unit. An adsorbing part having an adsorbing structure that adsorbs organic substances in the solution;
A valve for stopping the supply of the solution to the adsorption structure;
An ozone gas source for supplying gaseous ozone gas to the adsorption structure.   The solution processing apparatus according to claim 9, wherein the adsorption structure is made of ceramic.   The solution processing apparatus according to claim 10, wherein the ceramic has a hollow structure, and the solution is supplied to the hollow structure portion.   The solution processing apparatus according to claim 10, wherein the ceramic is porous.   The adsorption structure includes an outer wall, a plurality of flow paths provided on the inner side of the outer wall, and a partition wall that separates each of the plurality of flow paths from each other, and the partition wall communicates between adjacent flow paths. The solution processing apparatus according to claim 10, wherein the solution processing apparatus is a porous ceramic honeycomb structure having a plurality of communication holes to be formed and having an adsorption portion formed by the partition wall.   The solution processing apparatus according to claim 10, wherein a surface of the ceramic is alumina.   The solution processing apparatus according to claim 10, wherein the ceramic has a honeycomb shape or a sponge shape.   The solution processing apparatus according to any one of claims 9 to 15, further comprising a filtration unit having an RO membrane downstream of the adsorption unit. A first step of supplying a solution to the adsorption part in the adsorption structure;
A second step of supplying ozone gas to the adsorption structure in a state where supply of the solution to the adsorption structure is stopped after the completion of the first step;
And a third step of resuming the supply of the solution to the adsorption structure after completion of the second step.   The solution processing method according to claim 17, wherein the adsorption structure is made of ceramic.   The solution processing method according to claim 18, wherein the ceramic has a hollow structure, and the solution is supplied to the hollow structure portion.   The solution treatment method according to claim 18, wherein the ceramic is porous.   The adsorption structure includes an outer wall, a plurality of flow paths provided on the inner side of the outer wall, and a partition wall that separates each of the plurality of flow paths from each other, and the partition wall communicates between adjacent flow paths. 19. The solution processing method according to claim 18, wherein the solution processing method is a porous ceramic honeycomb structure having a plurality of communicating holes to be formed and having an adsorbing portion formed by the partition walls.   The solution processing method according to claim 18, wherein a surface of the ceramic is alumina.   23. The solution processing method according to claim 18, wherein the ceramic has a honeycomb shape or a sponge shape.   The solution processing method according to any one of claims 17 to 23, wherein the solution after the treatment in the adsorption unit is subjected to a filtration treatment in a filtration unit having an RO membrane.

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