Apparatus and method for decomposing organic matter in ammonia-containing water

Abstract

To provide an organic matter decomposition apparatus capable of efficiently decomposing organic matter in treated water containing ammonia and organic matter.SOLUTION: An organic matter decomposition apparatus 1 for ammonia-containing water includes ammonia reduction means 3 for reducing ammonia concentration by passing treated water W containing ammonia and organic matter therethrough, a gas permeable membrane apparatus 4, and an organic matter oxidation apparatus 5 consisting of three UV oxidation apparatus 5A, 5B, 5C. A circulation system is then formed so that water from the gas permeable membrane apparatus 4 is pumped to the organic matter oxidation apparatus 5, and water from the organic matter oxidation apparatus 5 is pumped to the gas permeable membrane apparatus 4.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for decomposing organic matter (TOC) in water containing ammonia and organic matter, and in particular to an apparatus and method for decomposing organic matter in ammonia-containing water that are suitable for treating condensed water generated during temperature and humidity control in closed spaces such as space stations, manned spacecraft, lunar bases, nuclear shelters, and disaster evacuation shelters. [Background technology]

[0002] Conventionally, in the treatment of condensed water generated during temperature and humidity control in the International Space Station (ISS), TOC is decomposed by catalytic oxidation under heating and pressurization conditions, as shown in Non-Patent Document 1. For this reason, not only is the energy of a heater required for heating, but it is also necessary to heat under oxygen gas injection conditions, so safety must be taken into consideration. Therefore, Patent Document 1 discloses a wet oxidation decomposition method in which wastewater containing organic compounds is brought into contact with a platinum group metal-supported catalyst and the organic compounds are catalytically oxidized by air supply. Although safety is improved, there is a problem that the decomposition efficiency is lower with air supply than with oxygen supply. In addition, development of catalysts with low-temperature activity is being promoted to ease temperature conditions, but there are problems with the oxidative decomposition efficiency.

[0003] On the other hand, ultraviolet oxidation technology is a compact TOC decomposition technology that does not require heating or heat retention. Ultraviolet rays are divided into near ultraviolet (200-400 nm), far ultraviolet (10-200 nm, also called vacuum ultraviolet), and extreme ultraviolet (10-121 nm) depending on the wavelength. Near ultraviolet rays are further divided into UVA (315-400 nm), UVB (280-315 nm), and UVC (200-2805 nm). When decomposing TOC, far ultraviolet or UVC is used. When the TOC concentration is low, for example, when decomposing trace amounts of TOC in ultrapure water, organic matter is decomposed by OH radicals generated by ultraviolet decomposition of water, but when treating water containing TOC exceeding 10 mg-C / L, hydrogen peroxide is generated from hydrogen atoms contained in organic matter and dissolved oxygen by high-energy far ultraviolet rays, and TOC can be efficiently decomposed by accelerated oxidation with the hydrogen peroxide and ultraviolet rays. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-111057 A [Non-patent literature]

[0005] [Non-Patent Document 1] D. Layne Carter, “Status of the Regenerative ECLSS Water Recovery System”, 37th International Conference on Environmental Systems; July 09, 2007 - July 12, 2007; Chicago, IL; United States Summary of the Invention [Problem to be solved by the invention]

[0006] However, previous studies on ultraviolet (UV) oxidation of TOC have shown that when TOC is decomposed by UV oxidation in the presence of ammonia, the decomposition efficiency of TOC drops significantly. The inventors have investigated the causes of this and speculate that the following two points are the cause. (1) The energy of ultraviolet light is consumed to oxidize ammonia to nitrogen and nitrate / nitrite, and the energy available for the oxidation of TOC is reduced. (2) TOC is oxidized by the oxidizing power of OH radicals generated by UV light, but nitrous acid generated by UV oxidation of ammonia acts as a scavenger of OH radicals, resulting in the OH radicals being consumed in ways other than for TOC decomposition.

[0007] In addition, when TOC-containing water is oxidized by UV irradiation, TOC decomposes to produce carbonic acid, which acts as a scavenger for OH radicals and reduces the efficiency of UV oxidation. In the presence of ammonia, the pH does not become low enough for decarbonation, and carbonic acid dissociates into ions in the water, which creates the problem that the carbonic acid concentration cannot be sufficiently reduced even if a gas permeable membrane device is used to decarbonate.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an organic matter decomposition device and a decomposition method that are capable of efficiently decomposing organic matter in treatment water that contains ammonia and organic matter. [Means for solving the problem]

[0009] In view of the above object, firstly, the present invention provides an apparatus for decomposing organic matter in water to be treated that contains ammonia and organic matter, the apparatus comprising: an ammonia reduction means for reducing the concentration of ammonia in the water to be treated that contains the ammonia and organic matter; a gas permeable membrane device for reducing carbon dioxide gas in the treated water of the ammonia reduction means; and an organic matter oxidation device having an ultraviolet oxidation device that passes the treated water through the gas permeable membrane device to decompose the organic matter (Invention 1).

[0010] According to this invention (Invention 1), the water to be treated, which contains ammonia and organic matter, is passed through an ammonia reduction means such as a cation exchange resin or an RO membrane to reduce the ammonia concentration, and then the water is treated in a downstream ultraviolet oxidation treatment device via a gas permeable membrane device, thereby enabling efficient decomposition of organic matter. It is presumed that the reason for this effect is due to the following three factors. That is, it is presumed that the combined effects are due to: 1) in the downstream ultraviolet oxidation device, the energy of ultraviolet light for oxidizing ammonia to nitrogen, nitric acid, and nitrous acid can be utilized for the oxidation of organic matter; 2) the generation of nitrous acid, which is a scavenger of OH radicals, from ammonia is suppressed, allowing the decomposition of organic matter by OH radicals to proceed smoothly; and 3) the reduction of ammonia lowers the pH of the treated water, making it easier to reduce carbonic acid, which is a scavenger of OH radicals, in the downstream gas permeable membrane device.

[0011] In the above invention (Invention 1), a circulation flow path is provided between the gas permeable membrane device and the organic matter oxidation device, and the circulation flow path is connected to a circulating water tank. Tamaki Po It is preferable that a pump is provided, and an inlet pipe for introducing the treated water from the ammonia reduction means into the circulation flow path and an outlet pipe for discharging the treated water from the organic matter oxidation device from the circulation flow path are connected to the circulation flow path (Invention 2).

[0012] According to this invention (Invention 2), the water to be treated, whose ammonia concentration has been reduced by the ammonia reduction means, is circulated between the gas permeable membrane device and the ultraviolet oxidation treatment device, and the organic matter concentration can be reduced to a desired value by adjusting the circulation time.

[0013] In the above invention (Invention 2), the circulation flow path allows water to pass through the circulating water tank, the circulating pump, and the organic oxidation device in that order, and is configured so that treated water from the organic oxidation device is sent to the circulating water tank, and the gas permeable membrane device is provided between the circulation pump and the organic oxidation device, or between the organic oxidation device and the circulating water tank, and it is preferable that the outlet pipe is connected to the circulation flow path between the organic oxidation device and the circulating water tank of the circulation flow path (Invention 3).

[0014] According to this invention (Invention 3), the treated water from the ammonia reduction means is introduced into the circulation flow path just before the gas permeable membrane device in the circulation flow path, and after circulating between the gas permeable membrane device and the ultraviolet oxidation treatment device, the treated water can be discharged from the circulation flow path, thereby obtaining treated water in which organic matter has been efficiently decomposed.

[0015] In the above inventions (Inventions 1 to 3), it is preferable that the pH of the water to be treated containing ammonia and organic matter is 4.6 or higher, and the pH of the water treated by the ammonia reducing means is 2 to 4.5 (Invention 4).

[0016] According to this invention (Invention 4), by removing ammonia from the water to be treated, which contains ammonia and organic matter, the pH of the treated water is lowered, and the inorganic carbon dioxide in the treated water can be efficiently removed as carbon dioxide gas in the downstream gas permeable membrane device.

[0017] Secondly, the present invention provides a method for decomposing organic matter in water to be treated that contains ammonia and organic matter, comprising the steps of: reducing the ammonia concentration in the water to be treated that contains ammonia and organic matter using an ammonia reducing means; reducing carbon dioxide in the treated water with the reduced ammonia concentration using a gas permeable membrane device; and subsequently subjecting the treated water with the reduced carbon dioxide concentration to ultraviolet oxidation treatment in an organic matter oxidation device having an ultraviolet oxidation device (Invention 5).

[0018] According to this invention (Invention 5), the water to be treated, which contains ammonia and organic matter, is passed through an ammonia reduction means such as a cation exchange resin or an RO membrane to reduce the ammonia concentration, and then passed through a gas permeable membrane device and treated in a downstream ultraviolet oxidation treatment device, thereby making it possible to efficiently decompose the organic matter.

[0019] In the above invention (Invention 5), a circulation system is formed between the gas permeable membrane device and the organic matter oxidation device, and it is preferable that treated water in which ammonia has been reduced by the ammonia reduction means is circulated through the circulation system while undergoing ultraviolet oxidation treatment (Invention 6).

[0020] According to this invention (Invention 6), the water to be treated containing ammonia and organic matter is circulated between the gas permeable membrane device and the ultraviolet oxidation treatment device, and the organic matter concentration can be reduced to a desired value by adjusting the circulation time.

[0021] In the above invention (Invention 6), it is preferable that the treated water from the ammonia reduction means is introduced into the circulation system through an inlet pipe connected to the circulation system at a stage downstream of the organic matter oxidizer and upstream of the gas permeable membrane device, and the treated water from the organic matter oxidizer is discharged through an outlet pipe connected to the circulation system at a stage downstream of the organic matter oxidizer and upstream of the connection part of the inlet pipe (Invention 7).

[0022] According to this invention (Invention 7), the treated water from the ammonia reduction means is introduced into the circulation system, and after circulating between the gas permeable membrane device and the ultraviolet oxidation treatment device for a predetermined period of time, the treated water is discharged from the circulation flow path, thereby efficiently obtaining treated water in which the organic matter concentration has been reduced to a desired value.

[0023] In the above inventions (Inventions 5 to 7), it is preferable that the pH of the water to be treated containing ammonia and organic matter is 4.6 or higher, and the pH of the water treated by the ammonia reducing means is 2 to 4.5 (Invention 8).

[0024] According to this invention (Invention 8), by reducing the ammonia in the water to be treated, which contains ammonia and organic matter, the pH of the treated water is lowered, and the carbonate ions in the treated water can be converted to carbonic acid and efficiently reduced in the downstream gas permeable membrane device. Effect of the Invention

[0025] According to the device for decomposing organic matter in ammonia-containing water of the present invention, the ammonia concentration of the water to be treated, which contains ammonia and organic matter, is reduced, and then the water passes through a gas permeable membrane device and is treated in a downstream ultraviolet oxidation treatment device, thereby efficiently decomposing the organic matter. [Brief description of the drawings]

[0026] [Figure 1] 1 is a schematic diagram showing an apparatus for decomposing organic matter in ammonia-containing water according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing an apparatus for decomposing organic matter in ammonia-containing water according to a second embodiment of the present invention. [Diagram 3] FIG. 11 is a schematic diagram showing an apparatus for decomposing organic matter in ammonia-containing water according to a third embodiment of the present invention. [Figure 4] 1 is a graph showing the relationship between the TOC concentration of treated water and treatment time in each run of Example 2. [Diagram 5] 13 is a graph showing the relationship between the TOC concentration of treated water and treatment time in each run of Comparative Example 2. [Figure 6] 1 is a graph showing TOC concentrations after 3 hours of circulation treatment in each run of Example 2 and Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] <First embodiment> DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an apparatus for decomposing organic matter in ammonia-containing water according to the present invention will be described below in detail with reference to the accompanying drawings.

[0028] [Apparatus for decomposing organic matter in ammonia-containing water] FIG. 1 shows an apparatus for decomposing organic matter in ammonia-containing water according to a first embodiment. In FIG. 1, the apparatus for decomposing organic matter in ammonia-containing water 1 comprises an ammonia reduction means 3 which reduces the ammonia concentration by passing water W to be treated which contains ammonia and organic matter through it, an inlet pipe 2A which supplies treated water from the ammonia reduction means 3 to a subsequent stage, a gas permeable membrane device 4, an organic matter oxidation device 5 consisting of multiple (three in this embodiment) ultraviolet oxidation devices 5A, 5B, 5C, and an outlet pipe 2B.

[0029] (Ammonia reduction means 3) In this embodiment, the ammonia reducing means 3 is not particularly limited as long as it can remove ammonia from the water to be treated, and a cation exchange resin, RO membrane, or the like can be suitably used. In particular, it is preferable to use a column packed with a non-regenerative strongly acidic cation exchange resin, since concentrated water is not generated. In addition, if the concentrated water can be disposed of or recovered, an RO membrane may be used.

[0030] (Gas permeable membrane device 4) In this embodiment, the gas permeable membrane device 4 can be one that passes the treated water from the ammonia reducing means 3 through one side (liquid phase side) of the gas permeable membrane that blocks water and allows gas to pass preferentially, and allows air to pass through the other side (gas phase side), thereby supplying oxygen necessary for the subsequent ultraviolet oxidation and removing carbon dioxide that inhibits the ultraviolet oxidation process. The gas permeable membrane may be any membrane that allows gases such as oxygen, nitrogen, and carbon dioxide to pass through but not water, and can be made of polyolefins such as polyethylene and polypropylene, or Teflon (registered trademark) such as PTFE, PFA, or PVDF.

[0031] (Organic oxidizer 5) In this embodiment, the organic matter oxidation device 5 is composed of three ultraviolet oxidation devices 5A, 5B, and 5C. The ultraviolet lamps installed in the ultraviolet oxidation devices 5A, 5B, and 5C can be selected from a low-pressure mercury lamp, a cold cathode lamp, an excimer lamp, and a plasma UV lamp. The ultraviolet lamp is preferably a lamp that irradiates at least far ultraviolet rays (10 to 200 nm). Alternatively, a lamp that simultaneously irradiates far ultraviolet rays and near ultraviolet rays (200 to 400 nm) may be selected, or a lamp that irradiates far ultraviolet rays and a lamp that irradiates near ultraviolet rays may be used in combination, so that TOC can be efficiently decomposed by accelerated oxidation of hydrogen peroxide generated by irradiation of far ultraviolet rays and near ultraviolet rays. Such ultraviolet oxidation devices 5A, 5B, and 5C may have any structure as long as they can irradiate the water to be treated while suppressing attenuation of ultraviolet rays. For example, a quartz tube is provided in the ultraviolet oxidation device, an ultraviolet lamp is provided inside the quartz tube, and the water to be treated is passed outside the quartz tube, whereby ultraviolet rays can be efficiently irradiated to the water to be treated. For example, a reactor structure such as that shown in Japanese Patent Application Laid-Open No. 6-134477 can be applied. When a quartz tube made of synthetic quartz is used, it has good ultraviolet light transmittance.

[0032] [Method for decomposing organic matter in ammonia-containing water] A method for decomposing organic matter in ammonia-containing water using the apparatus 1 for decomposing organic matter in ammonia-containing water according to this embodiment having the above-mentioned configuration will be described below.

[0033] (Water to be treated W containing ammonia and organic matter) The effect of this embodiment is more pronounced as the ammonia concentration of the water to be treated W containing ammonia and organic matter, which is the treatment target of this embodiment, increases. When the total amount of 1 mmol / L (17 mg / L) of ammonia becomes nitrite, it is calculated that 1 mmol / L (46 mg / L) of nitrite is generated. However, in reality, most of the ammonia becomes nitrogen gas and is removed to the gas phase side by the gas permeable membrane device 4, so that about 5 to 25% of the ammonia becomes nitrite, depending on the conditions of ultraviolet oxidation. Even if nitrite is oxidized to nitric acid by OH radicals, the nitric acid is reduced by UV light and returns to nitrite, so in order to reduce the nitrite concentration, it is necessary to simultaneously reduce the nitric acid concentration. Nitrite inhibits TOC decomposition as a radical scavenger even at a few mg / L, so the effect of improving the TOC decomposition efficiency by this embodiment becomes significant when the water to be treated contains ammonia at 3 mg / L or more.

[0034] In particular, condensed water generated during humidity control in closed spaces such as space stations, manned spacecraft, lunar bases, nuclear shelters, and disaster evacuation shelters contains an ammonia concentration of 20 mg / L or more due to ammonia evaporating from the human body, and also contains a TOC of 100 mg-C / L or more due to low molecular weight organic compounds that also evaporate from the human body, so the effects of applying this embodiment are remarkable.

[0035] (Ammonia reduction process) First, organic matter-containing water W containing ammonia as water to be treated W is supplied from an inlet pipe 2A to a cation exchange resin device as an ammonia reduction means 3. The amount of water to be treated W supplied at this time is preferably 0.02 to 1 times the amount of water that can be held in the downstream organic matter oxidation device 5. For example, when the amount of water in the ultraviolet oxidation device is 500 mL, the flow rate is preferably 10 to 500 mL / min.

[0036] In this ammonia reduction means 3, by passing the water W to be treated, the ammonia concentration in the water to be treated by the ammonia reduction means 3 is preferably less than 10 mg / L, more preferably less than 3 mg / L, and particularly preferably less than 1 mg / L. By reducing the ammonia concentration in the water W to be treated to less than 10 mg / L, it is possible to suppress the generation of nitrite, which is a scavenger of OH radicals that has a high organic matter decomposition power, in the downstream ultraviolet oxidation device, and by keeping the ammonia concentration less than 3 mg / L, it is possible to further suppress the generation of nitrite, and by keeping the ammonia concentration less than 1 mg / L, it is possible to almost completely eliminate the inhibition of organic matter decomposition due to the generation of nitrite. Furthermore, when the ammonia reduction means 3 is a cation exchange resin column, the SV of passing water through the cation exchange resin column is 0.01 to 2 min -1 By adjusting the amount of the cation exchange resin and the amount of water passed so as to satisfy the above condition, the cation exchange resin can be utilized most effectively, which is preferable.

[0037] By reducing the ammonia concentration in the water W to be treated by the ammonia reduction means 3 in this manner, the pH of the water W to be treated is lowered, and as described below, the carbonate ions in the water W to be treated are more easily removed as carbon dioxide gas in the gas permeable membrane device 4. Since carbonate ions capture highly oxidizing OH radicals generated by ultraviolet irradiation, a high concentration of inorganic carbon (IC) reduces the efficiency of oxidative decomposition of TOC. For this reason, the pH of the water treated by the ammonia reduction means 3 is preferably 5 or less, more preferably 4.5 or less, and even more preferably 4 or less.

[0038] (Degassing process) Next, the treated water from the ammonia reduction means 3 with reduced ammonia concentration is introduced into the gas permeable membrane device 4 through the introduction pipe 2. The gas permeable membrane device 4 is separated into a liquid phase side and a gas phase side by a gas permeable membrane, and the treated water from the ammonia reduction means 3 is passed through its liquid phase chamber, while air is passed through the gas phase chamber. This supplies oxygen required for oxidizing TOC in the organic matter oxidation device 5 at the downstream side from the gas phase side to the liquid phase side, and converts carbonate ions into molecular carbonic acid due to the decrease in pH, which is then removed from the liquid phase side to the gas phase side. The membrane area of ​​the gas permeable membrane device 4 is preferably determined so that the inorganic carbonic acid concentration of the treated water from the gas permeable membrane device is less than 3 mg-C / L, more preferably less than 1 mg-C / L.

[0039] (Ultraviolet oxidation process) Next, the treated water from the gas permeable membrane device 4, in which the carbon dioxide gas has been reduced, is subjected to ultraviolet oxidation treatment in the organic matter oxidation device 5, which has ultraviolet oxidation devices 5A, 5B, and 5C. Usually, hydrogen peroxide is generated by ultraviolet oxidation treatment, but the concentration is low, at only the order of μg / L. However, when far ultraviolet light is irradiated to water with a high organic matter concentration, high concentrations of hydrogen peroxide are generated by the reaction between hydrogen in the organic matter molecules and dissolved oxygen. For this reason, it is preferable to adjust the output and number of ultraviolet lamps irradiated by the ultraviolet oxidation devices 5A, 5B, and 5C so that the peak value of the hydrogen peroxide concentration is 1 to 50 mg / L, preferably 3 to 30 mg / L. The treated water W1, in which the TOC has been reduced by the organic matter oxidation device 5, is discharged through the discharge pipe 2B.

[0040] In this manner, the organic matter in the ammonia-containing water is decomposed, and treated water W1 with reduced TOC can be obtained.

[0041] Second Embodiment Next, a second embodiment of the apparatus for decomposing organic matter in ammonia-containing water according to the present invention will be described in detail with reference to the accompanying drawings.

[0042] [Apparatus for decomposing organic matter in ammonia-containing water] FIG. 2 shows an apparatus for decomposing organic matter in ammonia-containing water according to a second embodiment, which basically has the same configuration as the first embodiment described above, so the same components are given the same reference numerals and detailed descriptions thereof are omitted.

[0043] [Apparatus for decomposing organic matter in ammonia-containing water] In Figure 2, the apparatus 1 for decomposing organic matter in ammonia-containing water comprises an ammonia reduction means 3 for reducing the ammonia concentration by passing water to be treated (water to be treated) W containing ammonia and organic matter through it, a gas permeable membrane device 4, and an organic matter oxidation device 5 consisting of a plurality of (three in this embodiment) ultraviolet oxidation devices 5A, 5B, 5C. A circulation flow path 11 is connected so that water from the gas permeable membrane device 4 is sent to the organic matter oxidation device 5, and water from the organic matter oxidation device 5 is sent to the gas permeable membrane device 4. A circulating water tank 12 and a circulating pump 13 are provided in this circulation flow path 11, and the circulating water tank 12 and the circulating pump 13 are connected to the circulation flow path 11. Tamaki Po Water can pass through the pump 13, the gas permeable membrane device 4, and the organic matter oxidizer 5 in this order.

[0044] The introduction pipe 2A for introducing the treated water of the ammonia reducing means 3 into the circulation system is connected to the circulation water tank 12. Tamaki Po The circulation system is connected to a circulation flow path 11 between the organic oxidation device 5 and the circulating water tank 12, and the outlet pipe 2B of the treated water in the circulation system is connected to the circulation flow path 11 between the organic oxidation device 5 and the circulating water tank 12. Reference numeral 14 denotes a first three-way valve as a switching means for switching the flow path to the circulation pump 13 between the inlet pipe 2A and the circulation flow path 11, and reference numeral 15 denotes a second three-way valve as a switching means for switching the flow path from the organic oxidation device 5 between the circulation flow path 11 and the outlet pipe 2B. In this specification, the system in which water is circulated by the circulation pump 13 in the ultraviolet oxidation step described later is called the circulation system. That is, in FIG. 2, the circulation system is a system formed by the gas permeable membrane device 4, the organic oxidation device 5, the circulating water tank 12, the circulation pump 13, the circulation flow path 11, the first three-way valve 14, and the second three-way valve 15.

[0045] (Circulating water tank 12) In this embodiment, the circulating water tank 12 is not particularly limited as long as it can store water for the circulating system, but when applied to condensed water treatment in a space station or a manned spacecraft for a Moon or Mars mission, the circulating water tank cannot be an open tank due to the microgravity environment. In this case, a variable capacity tank must be used. As a variable capacity tank, a bag made of polypropylene or PFA, a piston type tank, or the like can be used.

[0046] [Method for decomposing organic matter in ammonia-containing water] A method for decomposing organic matter in ammonia-containing water using the apparatus 1 for decomposing organic matter in ammonia-containing water according to this embodiment having the above-mentioned configuration will be described below.

[0047] (Ammonia reduction process) First, the first three-way valve 14 is set to a state in which the line from the inlet pipe 2A of the treated water of the ammonia reduction means 3 to the circulation pump 13 is opened, and the second three-way valve 15 is set to a state in which the line from the circulation flow path 11 side, i.e., from the organic matter oxidation device 5 to the circulating water tank 12 is opened. Thereafter, the water to be treated W is passed through the ammonia reduction means 3. At this time, the supply amount of the water to be treated W is preferably set to 0.02 to 1 times the amount of water that can be held in the organic matter oxidation device 5 at the downstream stage.

[0048] The water W to be treated, the ammonia concentration of which has been reduced by the ammonia reduction means 3, passes through the gas permeable membrane device 4 and the organic matter oxidation device 5, and is stored in the circulating water tank 12 through the circulation flow path 11. When a predetermined amount of the water to be treated is filled in the circulating water tank 12, the liquid flow is stopped. In this step, the air sweep to the gas permeable membrane device 4 and the ultraviolet irradiation of the ultraviolet oxidation devices 5A, 5B, and 5C of the organic matter oxidation device 5 may be turned on or off. If at least the ultraviolet oxidation devices 5A, 5B, and 5C are turned on, the decomposition of TOC progresses not only in the ultraviolet oxidation step, which is the next step, but also in the ammonia reduction step, so that the processing time of the ultraviolet oxidation step described below can be shortened. When a cation exchange resin is used as the ammonia reduction means 3, the SV of water flowing through the cation exchange resin column is 0.01 to 2 min.-1 It is preferable to set it to .

[0049] (Ultraviolet oxidation process) In the ultraviolet oxidation step, the first three-way valve 1 is switched to a state in which the line from the circulating water tank 12 to the circulating pump 13 is circulated, and the second three-way valve 15 is left in a state in which the line from the circulating flow path 11, i.e., the organic matter oxidation device 5 to the circulating water tank 12, is circulated, forming a circulation system. Then, the circulation pump 13, the air sweep to the gas permeable membrane device 4, and the ultraviolet irradiation of the ultraviolet oxidation devices 5A, 5B, and 5C are turned on, and the water stored in the circulation tank 12, in which the ammonia concentration has been reduced, is circulated through the circulation flow path 11, thereby performing deaeration and ultraviolet oxidation continuously. Then, after a predetermined time of treatment, the circulation pump 13, the air sweep to the gas permeable membrane device 4, and the ultraviolet irradiation of the ultraviolet oxidation devices 5A, 5B, and 5C are turned off.

[0050] At this time, the circulation flow rate by the circulation pump 13 can be set to a flow rate that flows 0.2 to 10 times the amount of treated water from the ammonia reduction means 3 stored in the circulating water tank 12 per batch per minute. For example, when the organic matter oxidation device 5 processes 2 L of treated water from the ammonia reduction means 3 per batch, the circulation flow rate can be set to 0.4 to 20 L / min. Here, if the circulation flow rate is made too small, the liquid boundary film becomes thick in the ultraviolet oxidation devices 5A, 5B, and 5C and the gas permeable membrane device 4, and there is a concern that the oxidation efficiency of TOC in the organic matter oxidation device 5 and the oxygen dissolution efficiency and carbon dioxide removal efficiency in the gas permeable membrane device will decrease. In addition, the mixing of the liquid in the circulating water tank 12 will be poor, and the concentration will be unevenly distributed, and liquid with a high TOC concentration will remain in the circulating water tank 12. On the other hand, if the circulation flow rate is made too large, it may unnecessarily consume power from the circulation pump 13, and may also increase the pressure in the circulation flow path 11, causing water leakage and increasing the amount of drain water to the gas phase side of the gas permeable membrane device 4. Considering these effects, the circulation flow rate is preferably set to a flow rate that allows 1 to 10 times the amount of treated water from the ammonia reduction means stored in the circulating water tank for one batch to flow per minute, and more preferably to allow 2 to 5 times the amount.

[0051] Furthermore, in this step, it is preferable to adjust the membrane area of ​​the gas permeable membrane device 4 and the air sweep flow rate so that the dissolved oxygen concentration of the circulating water can be maintained at 4 mg / L or more. Specifically, the flow rate of the sweeping air is set to 0.05 to 1 times the amount of the water to be treated flowing to the liquid phase side under standard conditions, which is efficient from the viewpoints of removing carbon dioxide gas from the liquid phase to the gas phase and supplying oxygen gas from the gas phase to the liquid phase.

[0052] (Treated water discharge process) After the ultraviolet oxidation process is performed for a predetermined time, the treated water W1 is discharged. In this treated water discharge process, the first three-way valve 14 is left in the ultraviolet oxidation process (the first three-way valve 1 is in a state in which the line from the circulating water tank 12 to the circulating pump 13 is open), and the second three-way valve 15 is switched to a state in which the line from the organic matter oxidation device 5 to the outlet pipe 2B is open. After that, the circulation pump 13 is turned on, and the water from the circulating water tank 12 with reduced TOC is discharged from the outlet pipe 2B.

[0053] In this embodiment, the organic matter in the ammonia-containing water is decomposed to obtain treated water W1 with reduced TOC. In particular, by adjusting the circulation time in the ultraviolet oxidation step, the TOC concentration of the treated water W1 can be reduced to a desired value. For example, treated water W1 with a TOC concentration reduced to 1 mg-C / L can be obtained by circulating 2 L of water to be treated in one batch for 3 hours.

[0054] <Third embodiment> A third embodiment of the apparatus for decomposing organic matter in ammonia-containing water according to the present invention will be described in detail with reference to the accompanying drawings.

[0055] [Apparatus for decomposing organic matter in ammonia-containing water] FIG. 3 shows an apparatus for decomposing organic matter in ammonia-containing water according to a third embodiment, which basically has the same configuration as that of the second embodiment described above, and therefore the same components are given the same reference numerals and detailed descriptions thereof are omitted.

[0056] In the second embodiment described above, it is preferable to perform chemical cleaning when live bacteria occur in the circulation system such as the gas permeable membrane device 4, the circulation flow path 11, and the circulation water tank 12, or when dirt occurs in the quartz tubes of the ultraviolet oxidation devices 5A, 5B, and 5C. However, when a cation exchange resin column is used as the ammonia reduction means 3, passing a chemical through the cation exchange resin column may cause deterioration of the cation exchange resin or consumption before it reaches the circulation system if the chemical is an oxidizing agent, or may cause the chemical to be consumed before it reaches the circulation system if it is an acid or alkali, or may cause the adsorbed ammonia to break or the chemical to be consumed before it reaches the circulation system if it is a bactericide containing metal ions such as Ag or Cu. In this way, there are cases where it is not preferable to pass a chemical through the cation exchange resin column. In such a case, as shown in FIG. 3, a bypass flow path 21 may be provided in the cation exchange resin column as the ammonia reduction means 3, and three-way valves 22 and 23 may be provided as a switching mechanism at the junction of the bypass flow path 21 with the supply pipe 2. The three-way valve 23 may not be a valve, but may simply be a flow path that joins the inlet pipe 2A, or may be an inlet port provided at the top of the ion exchange column. Even if the three-way valve 23 is replaced with something other than a valve, it is possible to prevent the cleaning chemical from flowing back into the cation exchange resin column as long as the three-way valve 22 is in a state where the bypass flow path 21 side is open.

[0057] By adopting such a configuration, the chemical cleaning can be performed by bypassing the ammonia reducing means 3 and sending the chemical into the circulation system via the bypass flow path 21 line.

[0058] The present invention has been described above based on the above embodiment with reference to the attached drawings, but the present invention is not limited to the above embodiment and various modifications are possible. For example, in the second embodiment, an example was shown in which the first three-way valve 14 and the second three-way valve 15 are used as switching means, but two two-way valves may be used to switch the flow path instead of the three-way valves. In addition, the ultraviolet oxidation device constituting the organic matter oxidation device 5 is configured with three devices in the first to third embodiments, but it may be configured with one device, two devices, or four or more devices. In addition, the ultraviolet lamp installed in one ultraviolet oxidation device is not limited to being installed as one (piece), and multiple lamps may be installed. EXAMPLES

[0059] The present invention will now be described in further detail with reference to the following specific examples.

[0060] [Example 1] As a test device, an apparatus 1 for decomposing organic matter in ammonia-containing water, as shown in FIG. 1, was prepared. In this apparatus 1 for decomposing organic matter in ammonia-containing water, a column (inner diameter 70 mmφ) packed with 900 mL of strong acid cation exchange resin washed with pure water was used as the ammonia reduction means 3. The gas permeable membrane device 4 was a polypropylene membrane (membrane area 1.4 m 2 ) degassing membrane module was used. Compressor air was circulated at 1NL / min on the gas phase side of the degassing membrane. The organic matter oxidation device 5 was a series of three ultraviolet oxidation towers equipped with one 36W low-pressure ultraviolet lamp. The test device was initially filled with pure water.

[0061] Using this test equipment, simulated condensed water (water to be treated W) adjusted to 180 mg-C / L of alcohol and organic acids as TOC, 70 mg-C / L of ammonia, 26 mg-C / L of carbonic acid, and pH 7.2 to 7.8 was treated at a flow rate of 10 mL / min. During this treatment, the ammonia concentration of the outlet water from the cation exchange resin column 3 was measured, and the TOC concentration of the treated water W1 from the ultraviolet oxidation device was also measured.

[0062] As a result of the above measurements, the ammonia concentration of the outlet water of the cation exchange resin column 3 was always less than 0.1 mg / L. The TOC concentration of the treated water W1 from the ultraviolet oxidation device was less than 0.1 mg-C / L at the beginning of the flow because the pure water that had been filled in the system beforehand was pushed out, but it began to rise after 30 minutes, and the TOC concentration of the treated water W1 after 1 hour and 40 minutes was 33 mg-C / L. The carbon dioxide concentration of the treated water W1 was 12 mg-C / L.

[0063] [Comparative Example 1] The simulated condensed water was treated under the same conditions as in Example 1, except that the strong acid cation exchange resin column 3 was not provided, and the TOC concentration of the treated water W1 from the ultraviolet oxidation device was measured. As a result of this measurement, as in Example 1, the TOC concentration of the treated water W1 at the beginning of the flow was less than 0.1 mg-C / L, but after 30 minutes it rapidly increased, and after 1 hour the TOC concentration of the treated water W1 was 86 mg-C / L, resulting in a large amount of TOC remaining in the treated water W1.

[0064] [Example 2] As a test device, an organic matter decomposition device 1 in ammonia-containing water shown in Fig. 2 was prepared. In this organic matter decomposition device 1 in ammonia-containing water, the ammonia reduction means 3, the gas permeable membrane device 4, and the organic matter oxidation device 5 were the same as those in Example 1. In addition, a PFA shrink bag was used as the circulating water tank.

[0065] Using this test device, 2L of the simulated condensed water was treated 7 times (7 runs) in the same manner as in Example 1. Specifically, in the ammonia reduction step, the simulated condensed water was circulated at a flow rate of 0.5 L / min for 4 minutes, and in the ultraviolet oxidation step, circulation treatment was performed for 180 minutes at a circulation flow rate of 5 L / min. The treated water discharge step was a treatment for 4 minutes at a flow rate of 0.5 L / min. The other conditions were the same as in Example 1. At this time, the ammonia concentration and pH of the outlet water of the cation exchange resin column 3 were measured. In addition, the treated water W1 from the ultraviolet oxidation device was sampled and the TOC concentration was measured, and the results are shown in Table 1 and FIG. 4. Furthermore, the TOC concentration after 3 hours of treatment in each time (each run) is shown in FIG. 6.

[0066] [Table 1]

[0067] As a result of the above measurements, the ammonia in the outlet water from the ammonia reduction step (cation exchange resin column 3) was always less than 0.1 mg / L, and the pH was 3.7 to 3.8. As is clear from Table 1 and Figure 4, the TOC concentration of the treated water W1 in the first run (Run 1) was slightly low due to the fact that the liquid in the system at the start was pure water, but from the second run (Run 2) onwards, the treatment results were stable.

[0068] Furthermore, as is clear from FIG. 6, in Example 2, the TOC concentration after 180 minutes of UV treatment was reduced to 0.5 mg-C / L or less in all runs, and TOC was efficiently decomposed. In the circulating water in the UV oxidation process in the seventh run (Run 7), the peak values ​​of the carbonate concentration and nitrite ion were 1.4 mg-C / L and 0.15 mg / L, respectively, and the peak value of the hydrogen peroxide concentration was 15 mg / L. It is believed that the organic matter decomposition efficiency was improved by the fact that the pH was reduced by removing ammonia, which reduced the concentration of carbonate, a radical scavenger, and that the nitrite concentration was reduced by removing ammonia, which is the raw material for nitrite, another radical scavenger. In addition, the hydrogen peroxide concentration, which is derived from hydrogen in the organic matter, increased with the decomposition of the organic matter, and accelerated oxidation by hydrogen peroxide and UV rays occurred, which is believed to have increased the TOC oxidation efficiency due to a synergistic effect.

[0069] [Comparative Example 2] In Example 2, 2 L of simulated condensed water was treated 7 times (7 runs) under the same conditions as in Example 2, except that the water was not passed through the strongly acidic cation exchange resin column in the ammonia reduction process. In the ultraviolet oxidation process, circulation treatment was performed for 300 to 360 minutes at a circulation flow rate of 5 L / min. The TOC concentration of the treated water W1 from the ultraviolet oxidation device was measured at this time, and the results are shown in Table 1 and Figure 5. Furthermore, the TOC concentration after 3 hours of treatment in each run is also shown in Figure 6.

[0070] [Table 2]

[0071] As is clear from Table 2 and Figure 5, the TOC concentration in the first run (Run 1) was slightly low due to the fact that the liquid in the system at the start was pure water, and the TOC concentration in the second run (Run 2) also tended to be low due to the residual low-TOC treated water from the first run (Run 1) remaining in the gas permeable membrane device 4 and ultraviolet oxidation devices 5A, 5B, and 5C, but the treatment results were stable from the third run (Run 3) onwards. However, from the sixth run (Run 6) onwards, it was found that the TOC concentration could not be reduced to 10 mg-C / L or less even after 360 minutes of ultraviolet treatment.

[0072] As is clear from FIG. 6, in Comparative Example 2, in which the water was not passed through the strongly acidic cation exchange resin column 3 and ammonia was not reduced, the TOC decomposition efficiency of the circulating water decreased with each treatment, and even after 180 minutes of treatment, 40 mg-C / L or more remained. This is thought to be because the ammonia was not reduced by the cation exchange resin, and the energy of the ultraviolet light was consumed in the oxidation of ammonia. In addition, in the circulating water in the ultraviolet oxidation process in the seventh run (Run 7), the peak values ​​of the carbonate concentration and nitrite ion were 24 mg-C / L and 16 mg / L, respectively, which were higher than those in Example 2, and the peak value of the hydrogen peroxide concentration was 6 mg / L, which was lower than that in Example 2. It is thought that the TOC decomposition efficiency decreased due to radical scavenging by carbonate and nitrite. [Explanation of symbols]

[0073] 1. Equipment for decomposing organic matter in ammonia-containing water 2A introduction pipe 2B Outlet pipe 3. Ammonia reduction method (cation exchange resin column) 4. Gas permeable membrane device 5 Organic matter oxidation equipment 5A,5B,5C UV oxidation equipment 11 Circulation flow path 12 Circulating water tank 13 Circulation pump 14 First three-way valve (switching means) 15 Second three-way valve (switching means) 21 Bypass flow path 22, 23 Three-way valve (switching means)

Claims

1. An apparatus for decomposing organic matter in water to be treated that contains ammonia and organic matter, an ammonia reduction means for reducing the concentration of ammonia in the water to be treated that contains the ammonia and organic matter; a gas permeable membrane device for reducing carbon dioxide in the treated water of the ammonia reducing means; an organic matter oxidizing device having an ultraviolet oxidizing device that passes the treated water of the gas permeable membrane device through and decomposes the organic matter; Equipped with the ammonia reducing means is a cation exchange resin device; The apparatus for decomposing organic matter in ammonia-containing water, wherein the water to be treated containing ammonia and organic matter has a pH of 4.6 or more, an ammonia concentration of 20 mg / L or more, and a TOC of 100 mg-C / L or more.

2. 2. The apparatus for decomposing organic matter in ammonia-containing water according to claim 1, further comprising: a circulation flow path for circulating water between the gas permeable membrane device and the organic matter oxidation device; a circulating water tank and a circulation pump are provided in the circulation flow path; and an inlet pipe for introducing the treated water from the ammonia reduction means into the circulation flow path and an outlet pipe for discharging the treated water from the organic matter oxidation device from the circulation flow path are connected to the circulation flow path.

3. 3. The apparatus for decomposing organic matter in ammonia-containing water according to claim 2, wherein the circulation flow path allows water to pass through the circulating water tank, the circulating pump, and the organic matter oxidation device in that order, and the treated water from the organic matter oxidation device is sent to the circulating water tank, the gas permeable membrane device is provided between the circulation pump and the organic matter oxidation device, or between the organic matter oxidation device and the circulating water tank, and the outlet pipe is connected to the circulation flow path between the organic matter oxidation device and the circulating water tank.

4. An apparatus for decomposing organic matter in ammonia-containing water as described in any one of claims 1 to 3, wherein the pH of the treated water from the ammonia reduction means is 2 to 4.

5.

5. A method for decomposing organic matter in water to be treated that contains ammonia and organic matter, comprising the steps of: The ammonia concentration in the water to be treated containing the ammonia and organic matter is reduced by an ammonia reducing means; The carbon dioxide in the treated water with the ammonia concentration reduced is reduced using a gas permeable membrane device. Next, the treated water with reduced carbon dioxide gas is subjected to ultraviolet oxidation treatment in an organic matter oxidation device having an ultraviolet oxidation device, the ammonia reducing means is a cation exchange resin device; The method for decomposing organic matter in ammonia-containing water, wherein the water to be treated containing ammonia and organic matter has a pH of 4.6 or more, an ammonia concentration of 20 mg / L or more, and a TOC of 100 mg-C / L or more.

6. 6. The method for decomposing organic matter in ammonia-containing water according to claim 5, further comprising forming a circulation system between the gas permeable membrane device and the organic matter oxidation device, and circulating treated water in which ammonia has been reduced by the ammonia reduction means through the circulation system while performing ultraviolet oxidation treatment.

7. 7. The method for decomposing organic matter in ammonia-containing water according to claim 6, wherein the treated water from the ammonia reducing means is introduced into the circulation system through an inlet pipe connected to a stage downstream of the organic matter oxidizing device and a stage upstream of the gas permeable membrane device in the circulation system, and the treated water from the organic matter oxidizing device is discharged through an outlet pipe connected to a stage downstream of the organic matter oxidizing device and a stage upstream of the connection part of the inlet pipe in the circulation system.

8. A method for decomposing organic matter in ammonia-containing water described in any one of claims 5 to 7, wherein the pH of the treated water from the ammonia reduction means is 2 to 4.5.

Images