JP5749190B2 - Water treatment method and water treatment apparatus - Google Patents

Description

  Embodiments described herein relate generally to a water treatment method and a water treatment apparatus.

  Conventionally, ozone has been used for treatments such as oxidative decomposition, sterilization, and deodorization of organic substances in water in fields such as clean water, sewage, industrial wastewater, and pools. However, ozone has a weak oxidizing power and cannot be mineralized even if it can be made hydrophilic and low molecular. In addition, hardly decomposable organic substances such as dioxin and 1,4-dioxane cannot be decomposed.

  Therefore, when decomposing a hardly decomposable organic substance as described above, it is common to oxidize and decompose using OH radicals having a stronger oxidizing power than ozone (Patent Document 1). On the other hand, the OH radical is a very unstable substance and disappears in a short time, so that the lifetime is short, and there is a problem that the oxidative decomposition of the organic substance using the OH radical is inefficient.

  In view of such a problem, Patent Document 2 discloses that water to be treated is converted into water droplets from a shower nozzle and supplied into a discharge field generated between a cylindrical electrode and a linear electrode in the reaction tank. A technology for decomposing organic matter in water to be treated by filling a mixed gas containing 25 to 90% by volume of oxygen from the mixed gas supply means is disclosed. According to this technique, the OH radicals generated in the discharge field can be brought into contact with the water to be treated appropriately, so that even if the lifetime of the OH radical is short, the OH radical and the water to be treated Since contact efficiency can be improved, the oxidative decomposition of a hardly decomposable organic substance can be improved compared with the past.

  However, in the above technique, a shower nozzle or a cylindrical electrode and a linear electrode have to be provided at the upper part of the reaction tank, and there is a problem that the apparatus configuration becomes complicated and the operation method becomes complicated. there were.

JP 2000-279977 JP 2011-161212 A

  In the water treatment for oxidizing and decomposing dissolved organic matter in water, the present invention stably supplies the generated OH radicals to the treated water for a long time without complicating the apparatus and operation. The objective is to efficiently oxidize and decompose organic matter.

  The water treatment method of the embodiment is a water treatment method for oxidatively decomposing dissolved organic matter in water, the step of introducing treated water containing the dissolved organic matter into a reaction vessel, and generation of OH radicals in the reaction vessel And a step to perform. Furthermore, the method includes the step of measuring the amount of OH radicals generated at a plurality of locations from the upstream side to the downstream side, which is the introduction side of the water to be treated, in the reaction tank.

It is a figure which shows schematic structure of the water treatment apparatus in 1st Embodiment. It is a figure which shows schematic structure of the water treatment apparatus in 2nd Embodiment.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a water treatment apparatus in the present embodiment.
As shown in FIG. 1, the water treatment device 10 in the present embodiment includes a reaction vessel 11 and an ultraviolet light source 12 disposed in the reaction vessel 11. In addition, an inlet 11A for introducing treated water containing dissolved organic matter is provided in the lower part of the reaction tank 11, and the treated water containing dissolved organic substance is discharged to the outside at the upper part of the reaction tank 11. A drain outlet 11B is provided. In this case, since the water to be treated flows from the lower side (upstream side) to the upper side (downstream side) of the reaction tank 11, the ultraviolet light source 12 is supplied from the upstream side of the water to be treated in the reaction tank 11. It will be arranged along the direction toward the downstream side.

  The ultraviolet light source 12 is configured such that an ultraviolet lamp (not shown) is disposed in the waterproof case, and wiring (not shown) for the ultraviolet lamp is also connected to the reaction tank 11 through a pipe integrated with the waterproof case. It is taken out to the outside and connected to a predetermined power source (not shown).

  Further, OH radical generation amount measuring means 16, 17 and 18 are provided at three locations in the reaction tank 11 upstream, midstream and downstream, specifically at the lower, middle and upper portions of the ultraviolet light source 12.

  The first measuring means 16 for the amount of OH radical generation includes a pipe 161 in which the opening 161A is arranged facing the ultraviolet light source 12, the valve 162 provided in the pipe 161, and a storage tank provided at the end of the pipe 161. 163, a drain pipe 164 provided in the lower part of the storage tank 163, and a valve 165 provided in the drain pipe 164.

  The second measuring means 17 for the amount of OH radical generation includes a pipe 171 with the opening 171A facing the ultraviolet light source 12 side, a valve 172 provided on the pipe 171 and a storage tank provided at the end of the pipe 171. 173, a drain pipe 174 provided in the lower part of the storage tank 173, and a valve 175 provided in the drain pipe 174.

  Similarly, the third measuring means 18 for the amount of OH radicals generated is provided at the end of the pipe 181, the valve 182 provided in the pipe 181 and the pipe 181 in which the opening 181A is arranged facing the ultraviolet light source 12 side. A storage tank 183, a drain pipe 184 provided in the lower part of the storage tank 183, and a valve 185 provided in the drain pipe 184.

  In the first measuring unit 16, the second measuring unit 17, and the third measuring unit 18, the amount of OH radicals generated is measured in the storage tanks 163, 173, and 183 using a reagent, a discharge, or the like.

  In the present embodiment, three measuring means are provided to measure the amount of OH radicals generated at three locations in the reaction vessel 11, but the more measuring locations, the more preferable, and the provision of four or more measuring means. it can.

  A diffuser tube 14 is provided below the ultraviolet light source 12 in the reaction tank 11 for dispersing and introducing ozone, which is a raw material for OH radicals, into the reaction tank 11 via a pipe 15. Alternatively, hydrogen peroxide water may be added before the reaction tank 11 instead of ozone.

  In this embodiment, OH radicals are formed by the reaction between ozone or hydrogen peroxide and ultraviolet rays, so that the generation point of OH radicals is near the surface of the ultraviolet light source 12. Therefore, in order to accurately measure the amount of generated OH radicals, the openings 161A, 171A and 181A of the pipes 161, 171 and 181 of the measuring means 16, 17 and 18 are within the above range from the surface of the ultraviolet light source 12. To be located.

  In addition, each component of the water treatment apparatus 10 shown in FIG. 1 is comprised from the stainless material, fluorine resin, etc. which have high tolerance with respect to an acid.

Next, a water treatment method using the water treatment apparatus 10 shown in FIG. 1 will be described.
First, water to be treated containing dissolved organic matter is introduced into the reaction tank 11 from the inlet 11 </ b> A of the reaction tank 11. Next, ozone or hydrogen peroxide solution is introduced through the pipe 15 and dispersedly introduced into the reaction tank 11 through the air diffuser 14. Next, the ultraviolet light source 12 disposed in the reaction vessel 11 is turned on, and ozone or hydrogen peroxide introduced into the reaction vessel 11 is reacted with ultraviolet rays to generate OH radicals.

In addition, the production | generation of OH radical by reaction of ozone and an ultraviolet-ray is based on the following reaction formula.
O ₃ + H ₂ O + hv (ultraviolet light) → H ₂ O ₂ + O ₂
H ₂ O ₂ + hv (ultraviolet light) → 2OH · (OH radical)

  Further, ozone can be obtained by a general-purpose method such as oxygen gas discharge treatment.

On the other hand, the generation of OH radicals by the reaction between hydrogen peroxide and ultraviolet rays is based on the following reaction formula.
H ₂ O ₂ + hv (ultraviolet light) → 2OH · (OH radical)

  Next, the first measuring means 16, the second measuring means 17 and the third measuring means 18 provided for the reaction tank 11 are directed from the upstream side to the downstream side of the water to be treated in the reaction tank 11. Measure the amount of OH radicals produced. The density of OH radicals decreases in proportion to the square of its concentration. That is, it is said that the higher the density of OH radicals, the faster the OH radical extinction rate, and thus the shorter the lifetime, which is about 100 μsec.

  Therefore, when measuring the amount of OH radicals generated, the valves 162, 172 and 182 of the first measuring means 16, the second measuring means 17 and the third measuring means 18 are opened, and the pipes 161, 171 and 181 are opened. In addition, the storage tanks 163, 173, and 183 are always filled with the water to be treated in the reaction tank 11. For this reason, since the storage tanks 163, 173, and 183 are always filled with the water to be treated, the water to be treated is introduced into the storage tanks 163, 173, and 183, which are the measurement points of the generated amount. In the meantime, OH radicals do not disappear. As a result, it is possible to accurately measure the amount of OH radicals generated at the positions where the first measuring means 16, the second measuring means 17, and the third measuring means 18 in the reaction tank 11 are arranged.

  When measuring the amount of generated OH radicals, the valves 162, 172 and 182 of each measuring means are closed, and then a reagent is immediately added to the storage tanks 163, 173 and 183, and the color tone is monitored by a measuring instrument (not shown). After that, the amount of OH radicals generated is derived based on the correlation graph between the separately stored color tone data and the amount of OH radicals generated. In addition, after applying voltage to the storage tanks 163, 173 and 183 and monitoring the degree of luminescence with a measuring instrument (not shown), based on the correlation graph between the luminescence intensity and the amount of OH radicals generated separately, the OH radical Deriving the quantity.

  Examples of the reagent include p-nitrodimethylaniline and luminol.

  The generation point of the OH radical is in the vicinity of the surface of the ultraviolet light source 12 as described above. Therefore, in order to accurately measure the amount of generated OH radicals, the openings 161A, 171A and 181A of the pipes 161, 171 and 181 of the measuring means 16, 17 and 18 are within the above range from the surface of the ultraviolet light source 12. To be located.

  In the case of the present embodiment, ozone or hydrogen peroxide, which is a raw material for the OH radical, is introduced from the lower side of the reaction tank 11, and therefore generally the ozone or hydrogen peroxide concentration under the ultraviolet light source 12 is high. The concentration of ozone or hydrogen peroxide above the ultraviolet light source 12 is low. Therefore, the amount of OH radicals generated is large below the ultraviolet light source 12 and is small above the ultraviolet light source 12.

  For this reason, in order to efficiently oxidize and decompose the dissolved organic matter in the water to be treated introduced into the reaction tank 11 and to treat the water to be treated efficiently, the smallest OH radical generation amount among the measured OH radical production amount. The amount of OH radicals generated is controlled based on the amount of radicals generated. That is, the amount of OH radicals generated is controlled so that the smallest measured amount of OH radicals generated is equal to or greater than the amount of OH radicals generated. Specifically, when the intensity of the ultraviolet light source 12 is increased or the amount of ozone or hydrogen peroxide introduced into the reaction tank 11 is increased, the measured OH radical generation amount is the target OH radical generation amount. Try to be above.

  In addition, after measuring the production | generation amount of OH radical in the storage tanks 163, 173, and 183 in the 1st measurement means 16, the 2nd measurement means 17, and the 3rd measurement means 18, it has accumulated in these storage tanks. The water to be treated after measurement is discharged from the drain pipes 165, 175 and 185 with the valves 164, 174 and 184 opened. Next, after closing these valves, the valves 162, 172 and 182 are opened, and the water to be treated in the reaction tank 11 is treated with the pipes 161, 171 and 181 and the storage tanks 163, 173 and 183 are filled.

  The treated water that has been treated with OH radicals is discharged to the outside from the discharge port 11B of the reaction tank 11, and is subjected to purification treatment or the like as needed, and is discharged to a river or the like as waste water.

  As is clear from the above description, in the present embodiment, in the water treatment for oxidizing and decomposing dissolved organic matter in water, the generated OH radicals are treated for a long time with respect to the water to be treated without complicating the apparatus and operation. It is possible to supply stably and to efficiently treat the dissolved organic matter in the water to be treated by oxidative decomposition.

(Second Embodiment)
FIG. 2 is a diagram showing a schematic configuration of the water treatment apparatus in the present embodiment.
In the water treatment apparatus 10 shown in FIG. 1, OH radicals that oxidize dissolved organic substances in the water to be treated are generated through a reaction between ozone or hydrogen peroxide and ultraviolet rays. It is generated through the reaction of hydrogen peroxide. Therefore, as shown in FIG. 2, the water treatment apparatus 20 in the present embodiment is not provided with the ultraviolet light source 12 in the reaction tank 11, and ozone is supplied from the pipe 15 into the reaction tank 11 through the air diffuser 14. It is configured to be distributed. In addition, since it is the same as that of the water treatment apparatus 10 shown in FIG. 1 about another structure, description is abbreviate | omitted.

The water treatment method using the water treatment apparatus 20 shown in FIG. 2 is performed as follows.
First, water to be treated containing dissolved organic matter is introduced into the reaction tank 11 from the inlet 11 </ b> A of the reaction tank 11. Next, ozone is introduced through the pipe 15 and dispersedly introduced into the reaction tank 11 by the air diffuser 14. Ozone and hydrogen peroxide introduced into the reaction tank 11 generate OH radicals through the following reaction.

  Further, ozone can be obtained by a general-purpose method such as oxygen gas discharge treatment. Since ozone itself is also an unstable substance and will return to its original oxygen if left unattended, the apparatus for performing the discharge treatment or the like is in the middle of the piping 15 for introducing ozone, and is preferably a reaction vessel. It is arranged at a location close to 11.

  Next, the first measuring means 16, the second measuring means 17 and the third measuring means 18 provided for the reaction tank 11 are directed from the upstream side to the downstream side of the water to be treated in the reaction tank 11. Measure the amount of OH radicals produced. As described above, the density of the OH radical decreases in proportion to the square of its concentration, and the lifetime of the OH radical is shortened because the OH radical disappearance rate is increased.

  Therefore, when measuring the amount of OH radicals generated, the valves 162, 172 and 182 of the first measuring means 16, the second measuring means 17 and the third measuring means 18 are opened, and the pipes 161, 171 and 181 are opened. In addition, the storage tanks 163, 173, and 183 are always filled with the water to be treated in the reaction tank 11. For this reason, since the storage tanks 163, 173, and 183 are always filled with the water to be treated, the water to be treated is introduced into the storage tanks 163, 173, and 183, which are the measurement points of the generated amount. In the meantime, OH radicals do not disappear. As a result, it is possible to accurately measure the amount of OH radicals generated at the positions where the first measuring means 16, the second measuring means 17, and the third measuring means 18 in the reaction tank 11 are arranged.

  When measuring the amount of generated OH radicals, the valves 162, 172 and 182 of each measuring means are closed, and then a reagent is immediately added to the storage tanks 163, 173 and 183, and the color tone is monitored by a measuring instrument (not shown). After that, the amount of OH radicals generated is derived based on the correlation graph between the separately stored color tone data and the amount of OH radicals generated. In addition, after applying voltage to the storage tanks 163, 173 and 183 and monitoring the degree of luminescence with a measuring instrument (not shown), based on the correlation graph between the luminescence intensity and the amount of OH radicals generated separately, the OH radical Deriving the quantity.

  Examples of the reagent include p-nitrodimethylaniline and luminol.

  In this embodiment, since the generation point of OH radicals extends throughout the reaction tank 11, the openings 161A, 171A and 181A of the pipes 161, 171 and 181 of the measuring means 16, 17 and 18 are, for example, It is located in the center of the reaction vessel 11.

  Also in this embodiment, ozone or hydrogen peroxide, which is a raw material for OH radicals, is introduced from the lower side of the reaction tank 11, and therefore, generally, the concentration of OH radicals in the lower part of the reaction tank 11 is high. The concentration of OH radicals above is low.

  For this reason, in order to efficiently oxidize and decompose the dissolved organic matter in the water to be treated introduced into the reaction tank 11 and to treat the water to be treated efficiently, the smallest OH radical generation amount among the measured OH radical production amount. The amount of OH radicals generated is controlled based on the amount of radicals generated. That is, the amount of OH radicals generated is controlled so that the smallest measured amount of OH radicals generated is equal to or greater than the amount of OH radicals generated. Specifically, the amount of ozone and hydrogen peroxide introduced into the reaction vessel 11 is increased so that the measured OH radical production amount becomes equal to or greater than the target OH radical production amount. Since other operations are the same as those in the first embodiment, description thereof is omitted.

  As is clear from the above description, in the present embodiment, in the water treatment for oxidizing and decomposing dissolved organic matter in water, the generated OH radicals are treated for a long time with respect to the water to be treated without complicating the apparatus and operation. It is possible to supply stably and to efficiently treat the dissolved organic matter in the water to be treated by oxidative decomposition.

  As mentioned above, although several embodiment of this invention was described, these embodiment was posted as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10,20 Water treatment apparatus 11 Reaction tank 12 Ultraviolet light source 14 Aeration pipe 15 Piping 16 1st measurement means 17 2nd measurement means 18 3rd measurement means

Claims (3)

A water treatment method for oxidative decomposition of dissolved organic matter in water,
Introducing the treated water containing the dissolved organic matter into the reaction vessel;
In the reaction tank, after supplying at least one of ozone and hydrogen peroxide, the ultraviolet light is irradiated from an ultraviolet light source arranged along the direction from the upstream side, which is the introduction side of the water to be treated, to the downstream side. Generating OH radicals by reacting ozone with at least one of ozone and hydrogen peroxide ;
In the reaction tank, at a plurality of locations from the upstream side to the downstream side that is the introduction side of the water to be treated, the water to be treated is provided via a plurality of water sampling tubes arranged so that the openings face the ultraviolet light source. Sampling each of the water, measuring the amount of OH radicals produced in the treated water sampled from the sampling tube ;
A water treatment method comprising the steps of:   2. The water treatment method according to claim 1, wherein the amount of OH radicals generated in the reaction vessel is controlled based on a minimum amount of the OH radicals measured at the plurality of locations. A water treatment device for oxidative decomposition of dissolved organic matter in water,
A reaction vessel for oxidatively decomposing the treated water containing the dissolved organic matter with OH radicals;
An ultraviolet ray emitted from the ultraviolet light source, having a pipe for supplying at least one of ozone and hydrogen peroxide and an ultraviolet light source disposed along the direction from the upstream side to the downstream side of the water to be treated in the reaction tank. OH radical generating means for generating the OH radical by reacting ozone and at least one of hydrogen and hydrogen supplied from the pipe ,
A plurality of water sampling tubes arranged in such a manner that openings are directed to the ultraviolet light source at a plurality of locations from the upstream side to the downstream side, which is the introduction side of the treated water, in the reaction tank, and the plurality of water sampling tubes Each of which includes storage tanks, and the amount of OH radicals generated is measured by measuring the amount of the OH radicals in the water to be treated introduced into the plurality of storage tanks via the plurality of sampling pipes. and OH radical generation amount measuring means for measuring the production amount of the OH radicals by,
A water treatment device characterized by comprising:

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