Ozone scrubber and ozone scrubbing method

Abstract

A method for scrubbing ozone in an ozone scrubber (10) comprising a gas-liquid contactor (20) adapted to contact an inlet gas containing ozone with a reducing liquid (15), the method comprising the steps of: supplying the inlet gas to the gas-liquid contactor (20); supplying fresh reducing liquid to the gas-liquid contactor (20), the fresh reducing liquid comprising an aqueous solution of a reducing agent; and scrubbing the ozone from the inlet gas by reduction reaction with the reducing liquid under acidic pH conditions.

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for scrubbing or destroying ozone present in a gas stream. [Background technology]

[0002] Ozone (O3) is known for its various properties, including sterilization, pest control, cleaning, and bleaching. Therefore, it is widely used in many industries, such as water treatment, agriculture, industrial food processing, healthcare, and papermaking.

[0003] Ozone is also considered a pollutant in the biosphere and must be broken down before being released into the environment. For this purpose, ozone pyrolysis and ozone catalytic decomposition have been proposed.

[0004] Ozone pyrolysis devices rely on the fact that ozone is unstable and its half-life decreases very rapidly as the temperature rises. A gas stream containing residual ozone to be decomposed is passed through a reactor equipped with a heater. The gas is heated to several hundred degrees Celsius so that the ozone half-life becomes extremely short. The reactor is designed to allow the gas stream to remain in the reactor for a sufficiently long time to reduce the ozone, based on the ozone half-life at the operating temperature.

[0005] This method has the disadvantage of being energy-intensive because the entire gas flow must be heated even when the residual ozone concentration in the gas flow is very low. To reduce energy consumption, it is possible to use a heat recovery system, i.e., a heat exchanger that transfers heat between the hot gas at the decomposer outlet and the cold gas at the decomposer inlet. While such a solution is very effective in reducing energy operating costs, heat exchangers are relatively expensive, increasing the investment cost of the entire ozone solution (ozone generator and ozone decomposer). Furthermore, other chemicals may be present in the ozone inlet gas, which can damage the pyrolysis unit, for example, by causing corrosion.

[0006] In an ozone catalytic decomposer, the reactor is filled with catalyst in particulate form. The ozone inlet gas flows through the catalyst parts that induce ozone decomposition. The operating costs of such an ozone catalytic decomposer are lower than those of an ozone pyrolysis unit.

[0007] However, ozone catalytic decomposers have the disadvantage of using catalysts that are sensitive to several chemicals (e.g., sulfur compounds) and can be easily poisoned. This leads to frequent catalyst replacement, resulting in high operating costs and potentially significant environmental impact. Therefore, ozone catalytic decomposers cannot be used in all industrial processes.

[0008] Finally, International Publication No. 93 / 18226 discloses an ozonolysis method comprising the step of scrubbing a gas stream with an alkaline liquid containing dissolved organic matter, the alkaline liquid being available, for example, from a papermaking process.

[0009] However, the inventors determined that the selectivity of the reaction between an alkaline liquid and ozone is not as high as that of the competitive reaction between an alkaline liquid and oxygen, and therefore, the above-described prior art process cannot efficiently decompose ozone or significantly reduce the ozone content in the gas after the process.

[0010] Therefore, there is a need for an ozone decomposer or ozone scrubber that can process industrial gases containing ozone with high efficiency and low operating costs. [Overview of the project]

[0011] This objective is achieved in a first aspect of the present invention by a method of scrubbing ozone in an ozone scrubber equipped with a gas-liquid contact device adapted to bring an inlet gas containing ozone into contact with a reducing solution, the method being a) A step of supplying inlet gas to a gas-liquid contact device, b) A step of supplying a new reducing solution to a gas-liquid contactor, wherein the new reducing solution contains an aqueous solution of a reducing agent. c) A step of scrubbing the inlet gas ozone by a reduction reaction with a reducing solution under acidic pH conditions.

[0012] By selecting acidic pH conditions, the ozone decomposition yield can be increased, i.e., the consumption of reducing agent to decompose most or all of the ozone in the inlet gas can be reduced. Therefore, this method is cost-effective. Acidic pH conditions can be obtained from the acidic liquid supplied into the gas-liquid contactor and / or from the acidic reaction products of the reduction reaction. Furthermore, heating can be avoided, and the reduction reaction can be carried out at room temperature. For example, no catalyst is used in the gas-liquid contactor. The above steps are preferably carried out simultaneously in a continuous process. Alternatively, a batch process can be considered. Finally, it is preferable that the new reducing solution is supplied countercurrently to the inlet gas.

[0013] Advantageously, the reducing agent is selected such that the reduction reaction in the scrubbing step produces an acidic reaction product, which contributes to at least part of the acidic conditions.

[0014] Therefore, acidic pH conditions can be maintained in the gas-liquid contact apparatus by adding or not adding acidic liquids or reagents in limited amounts. This contributes to the high ozonolysis yield and high cost-efficiency of this method. Preferably, no reagents other than ozone and the reducing agent are added in the reduction reaction.

[0015] Advantageously, the reducing agent is based on sulfur and / or phosphorus compounds. Such reducing agents are readily available and can yield acidic reaction products.

[0016] Advantageously, the reducing agent includes sulfites, bisulfites, metabisulfites, and / or thiosulfates. Such reducing agents may also be present in wastewater from industrial processes such as paper pulp manufacturing, which further contributes to the cost-effectiveness of the process. Preferably, the reducing agent is a sulfite or contains sulfites.

[0017] Advantageously, the method of the present invention includes a step of recirculating at least a portion of the reducing solution throughout the gas-liquid contact apparatus during the scrubbing step. As a result, the acidic reaction product can contribute more efficiently to the acidic reaction conditions, which is preferable in terms of ozonolysis yield and cost-effectiveness.

[0018] In the process of supplying a new reducing solution into the gas-liquid contactor, it is advantageous to maintain the acidic pH conditions within the gas-liquid contactor by controlling the flow rate of the new reducing solution. As a result, the acidic reaction products can contribute to the acidic reaction conditions more efficiently, which is preferable in terms of ozonolysis yield and cost efficiency. For example, the pH may be 6 or less, preferably 5 or less, preferably less than 4, and even more preferably less than 3. The pH may be greater than 0, or 1 or 2 or greater.

[0019] Advantageously, maintaining a constant pH during the process of maintaining acidic pH conditions yields the best results in terms of ozonolysis yield. For example, a constant pH could be 2.5.

[0020] Advantageously, the acidic reaction product is sulfuric acid and / or sodium bisulfate. Such acidic reaction products can be readily obtained from reducing solutions containing sulfites, bisulfites, metabisulfites, and / or thiosulfates. They can contribute to the acidic pH conditions of the reduction reaction without significant side reactions. In the reduction reaction, a pH of 4 or less, 3 or less, preferably 2.5 can be maintained.

[0021] Advantageously, the reduction reaction further generates oxidation reaction products, and this method, d) After the reduction reaction, i.e., after circulation within the gas-liquid contact device, a step of temporarily storing at least a portion of the reducing solution in a tank or the tank section of the gas-liquid contact device, e) A step of supplying fresh water into the tank and / or the gas-liquid contact device, f) A step of discharging a portion of the reducing solution from the tank or the tank section, g) controlling the concentration of the oxidation reaction product in the reducing liquid by acting on the flow rate of the supplied water and / or the discharged reducing liquid, further comprising the step of:

[0022] Such additional features may make it possible to prevent precipitation of oxidation reaction products in the ozone scrubber and sustain continuous ozone decomposition. The oxidation reaction product may be formed from an acidic reaction product, or may be in equilibrium with the acidic reaction product. For example, the oxidation reaction product is sodium sulfate. Water such as tap water, industrial water or fresh water may be supplied simultaneously with the reducing liquid.

[0023] A second aspect of the present invention is an ozone scrubber adapted to perform the method for scrubbing ozone according to the first aspect of the present invention, the ozone scrubber comprising: a) a gas-liquid contactor, b) a gas inlet supply adapted to supply inlet gas, c) a fresh liquid supply adapted to supply fresh reducing liquid, The ozone scrubber comprises recirculation means configured to recirculate at least a portion of the reducing liquid throughout the gas-liquid contactor.

[0024] Such an ozone scrubber is particularly adapted to the present method, making it possible to obtain a high ozone decomposition yield and high cost efficiency.

[0025] Advantageously, the ozone scrubber further comprises a pH control device configured to maintain acidic pH conditions in the gas-liquid contactor and / or in the recirculation means by controlling the flow rate of the fresh liquid supply. In other words, the pH control device can maintain constant acidic pH conditions during the reduction reaction.

[0026] Advantageously, the ozone scrubber comprises: d) a tank or a tank portion of the gas-liquid contactor adapted to temporarily store the reducing liquid after circulation in the gas-liquid contactor and before recirculation, e) a water supply adapted to supply water into the gas-liquid contactor or into the tank, f) A liquid discharge section adapted to discharge a portion of the reducing solution from the tank or tank section, g) A reaction product control device adapted to control the concentration of oxidation reaction products in the reducing solution by controlling the flow rate of supplied water and / or the flow rate of discharged reducing solution.

[0027] Advantageously, the gas-liquid contact apparatus is a plate column. Such a gas-liquid contact apparatus can optimize ozonolysis. Alternatively, other gas-liquid contact apparatuses may be used. [Brief explanation of the drawing]

[0028] Further advantages and preferred embodiments of the present invention will become apparent from the following detailed description and drawings.

[0029] [Figure 1] This is a schematic diagram of an ozone scrubber according to one aspect of the present invention. [Modes for carrying out the invention]

[0030] This ozone scrubber and ozone scrubbing method are intended to scrub or decompose ozone in inlet gases discharged from industrial processes such as water treatment, food disinfection, or papermaking. Ozone Scrub

[0031] Referring to Figure 1, an ozone scrubber 10 according to one embodiment of the present invention comprises a gas-liquid contact device 20 in the form of a plate column provided with, for example, a perforated plate 21. The gas-liquid contact device 20 is provided with a top portion having a gas outlet 22. A tank 30 is connected to the base of the gas-liquid contact device 20. The tank 30 is provided with a gas inlet supply unit 31 adapted for supplying an inlet gas containing ozone, a liquid discharge unit 32 adapted for discharging or releasing liquid from the tank 30, and a liquid recirculation outlet 41.

[0032] The recirculation outlet 41 is fluidly connected to a pumping means, such as a pump 42, which is adapted to deliver the reducing solution 15 into the recirculation pipe 43 toward a liquid supply unit 44 provided in the gas-liquid contact device 20. The liquid supply unit 44 is preferably positioned to supply liquid to the portion of the gas-liquid contact device opposite to the portion connected to the tank 30, or at least to the portion opposite to the gas inlet supply unit 31. In the preferred embodiment shown in Figure 1, the gas inlet supply unit is located in the tank 30 at the bottom of the ozone scrubber 10, and the liquid supply unit 44 is located at the top of the ozone scrubber 10, i.e., at the top of the gas-liquid contact device 20. The recirculation outlet 41, pump 42, recirculation pipe 43, and liquid supply unit 44 define the recirculation means 40.

[0033] As a result, in the preferred embodiment shown in Figure 1, the inlet gas containing ozone rises from the tank 30 through the perforated plate 21 towards the top of the gas-liquid contact device 20, following the upward arrow in Figure 1. The reducing liquid 15 descends, following the downward arrow in Figure 1, and its downward flow is restricted by the perforated plate 21.

[0034] Furthermore, the recirculation pipe 43 is provided with a new liquid supply section 50 and a water supply section 60. The new liquid supply section 50 is adapted to supply a new reducing solution selected so that an acidic reaction product is produced by reaction with ozone. The water supply section is adapted to supply fresh water or water suitable for the reaction carried out in the gas-liquid supply section, such as an aqueous effluent containing an acidic compound, to the ozone scrubber 10.

[0035] Furthermore, the ozone scrubber may include a pH control device 70 and a reaction product control device 80. The pH control device 70 is connected to a valve in the fresh liquid supply unit 50 and to one or more pH sensors provided in the tank 30 in Figure 1. The pH control device 70 may be alternatively or in combination to be connected to one or more pH sensors provided in the gas-liquid contact device 20 and / or the recirculation pipe 43, and is programmed to maintain at least an acidic pH, for example, less than 6.5, preferably a lower pH.

[0036] The reaction product control device 80 may be connected to a valve in the water supply unit 60, a valve in the liquid discharge unit 32, and an oxidation reaction product sensor adapted to detect or measure the concentration of oxidation reaction products in the reducing solution 15. The reaction product sensor is, for example, a redox sensor and may be provided in the tank 30 as shown in Figure 1, and / or in the gas-liquid contact device 20 or the recirculation pipe 43.

[0037] Pump 42 may be any type of pump adapted to move liquids, particularly acidic and / or reducing solutions. These include centrifugal pumps, peristaltic pumps, gear pumps, screw pumps, and lobe pumps. The pumping rate and / or flow rate of the reducing solution recirculated by pump 42 can be controlled, for example, based on the gas inlet flow rate at the gas inlet 31 and / or the ozone concentration at the gas outlet 22. Preferably, the ozone concentration at the gas outlet 22 may be 100 ppb or less, in accordance with local regulations.

[0038] In other embodiments, the fresh liquid supply unit may be connected to a fresh liquid inlet located, for example, on the top and / or tank of the gas-liquid contact device. Similarly, the water supply unit may be connected to the fresh liquid supply unit, or to a water supply inlet located, for example, on the top and / or tank of the gas-liquid contact device.

[0039] The gas-liquid contact apparatus 20 in Figure 1 is a plate column, but any gas-liquid contact apparatus may be used. For example, the gas-liquid contact apparatus may be a thin-film flow column, a packed column, a bubble column, a spray column, a gas-liquid stirring vessel, a rotating disk contactor, or a Venturi tube.

[0040] Depending on the type of gas-liquid contactor and the specific process, the tank may be integrated into the gas-liquid contactor in the form of a tank section. For example, the bottom of the gas-liquid contactor may be filled with reducing solution to function as a tank section, and a recirculation outlet may be located in the tank section of such a gas-liquid contactor. The liquid discharge section may be located in the tank section and / or derived from the recirculation outlet or recirculation pipe. Finally, the gas inlet may be located in the tank section or bottom of the gas-liquid contactor.

[0041] The ozone scrubber 10 is equipped with all valves, piping, sensors and safety measures required by regulations and / or good manufacturing practices, as is known to those skilled in the art. Ozone scrubbing method

[0042] Herein, an ozone scrubbing method using an ozone scrubber 10 is disclosed. For example, an inlet gas containing 5-15%, or for example, about 10% v / v of ozone, is supplied to the gas-liquid contact device 20. This inlet gas may be generated from an industrial process containing ozone, such as paper pulp manufacturing, and for safety and environmental reasons, it must be decomposed before being released into the environment.

[0043] A new reducing solution is supplied to the gas-liquid contact device 20. This new reducing solution is preferably selected so as to produce an acidic reaction product through reaction with ozone. For example, the new reducing solution contains one or more reducing agents that react with ozone to produce one or more acidic reaction products.

[0044] At least a portion of the reducing solution 15 contained in the ozone scrubber 10 is recirculated throughout the gas-liquid contactor 20 after contact with the inlet gas. This recirculation may be performed by a recirculation means 40 and is intended to optimize the contact time between the inlet gas and the reducing solution 15 and to provide acidic pH conditions to the gas-liquid contactor 20 and the reducing solution 15. Recirculation can contribute to maintaining acidic pH conditions for the reduction reaction.

[0045] Furthermore, an acidic pH condition can be maintained within the gas-liquid contact device by a pH control device 70 that controls the supply of new reducing solution to the gas-liquid contact device. In fact, the reducing solution does not have to be acidic; it may be neutral or basic. Therefore, it is preferable to adjust or control the flow rate of the new reducing solution supply to maintain the acidic pH condition within the gas-liquid contact device (i.e., in the reducing solution). Preferably, the supply of new reducing solution is controlled so that a constant acidic pH is maintained within the gas-liquid contact device.

[0046] This reduction reaction may produce oxidation reaction products. These oxidation reaction products may be formed from and / or in equilibrium with acidic reaction products. Alternatively, only oxidation reaction products may be formed, and no acidic reaction products may be formed. Preferably, the concentration of the oxidation reaction products can be controlled as follows.

[0047] At least a portion of the reducing solution 15 reacts with ozone in the tank 30 or the tank section of the gas-liquid contact device 20, and is stored before, for example, the reducing solution 15 is recirculated to the entire gas-liquid contact device 20.

[0048] Fresh water is supplied into the tank 30 or the gas-liquid contact device 20, and a portion of the reducing solution 15 is discharged from the tank 30 or the tank section of the gas-liquid contact device 20.

[0049] Thus, the concentration of oxidation reaction products in the reducing solution 15 is controlled by the reaction product control device 80, which acts on the flow rate of the fresh water supply unit 60 and / or the liquid discharge unit 32. This makes it possible to avoid undesirable side reactions and / or precipitation of oxidation reaction products that may occur in the gas-liquid contact device 20. chemical details

[0050] Although not bound by any particular theory, ozone can be decomposed by this method by reducing it to oxygen. The reducing agent can then be oxidized and / or hydrolyzed to produce acidic reaction products.

[0051] The inlet gas containing ozone typically also contains oxygen, a strong oxidizing agent. The inventors determined that, under acidic conditions, the selectivity of the reaction between the reducing agent and ozone is better than that of the reaction between the reducing agent and oxygen. In other words, under acidic pH conditions, the reducing agent reacts faster with ozone than with oxygen.

[0052] For example, the reducing solution contains water or at least a protic solvent such as an alcohol as the solvent, and the reducing agent can be selected from potassium sulfite or sodium sulfite (Na2SO3), potassium bisulfite or sodium bisulfite (NaHSO3), potassium metabisulfite or sodium metabisulfite (Na2S2O5), potassium thiosulfate or sodium thiosulfate (Na2S2O3), water-soluble organophosphorus such as tris(2-carboxyethyl)phosphine, cysteine ​​salts, nitrites such as potassium nitrite or sodium nitrite (NaNO2), water-soluble salts of ethylenediaminetetraacetic acid (its EDTA salt), phosphinates and / or phosphates.

[0053] Preferably, the reducing agent is a sulfur reducing agent such as potassium sulfite or sodium sulfite (Na2SO3), potassium bisulfite or sodium bisulfite (NaHSO3), potassium metabisulfite or sodium metabisulfite (Na2S2O5), potassium thiosulfate or sodium thiosulfate (Na2S2O3), or contains such an agent. Preferably, the reducing solution contains at least potassium sulfite or sodium sulfite (Na2SO3).

[0054] In the case of reducing agents based on sulfites or bisulfites, the following equilibria are established in water between sulfite, bisulfite, and sulfite, respectively: H2O , SO2⇔HSO3 - ⇔SO3 2- .

[0055] Numerous reactions can occur between these reducing agents and ozone, but the most significant reactions are as follows: H2O + SO3 2- +O3 → SO4 2- +H+ H2O+HSO3 - +O3→SO4 2- +H + H2O+H2O , SO2 2- +O3→SO4 2- +H +

[0056] As a result, the reaction between the reducing agent and ozone generates sulfuric acid and / or bisulfite as acidic reaction products. The reducing liquid containing the sulfur reducing agent may be neutral or alkaline before being introduced into the gas-liquid contact apparatus, but becomes acidic due to the generation of the acidic reaction product and the recirculation of the reducing liquid. In fact, the more the reducing liquid is recirculated in the gas-liquid contact apparatus, the higher the concentration of the acidic reaction product in the reducing liquid, and the more acidic the reducing liquid becomes, that is, the lower the pH value decreases.

[0057] In this way, by using this acidic reaction product, which is a by-product of the reaction between the sulfur reducing agent and ozone, in the present invention, the acidic pH condition in the gas-liquid contact apparatus can be promoted. In addition, the oxidation reaction product in the form of sodium sulfite may be formed from the acidic reaction product and / or the reduction reaction. As is known, such oxidation reaction products may precipitate when exceeding a specific concentration in the reducing liquid.

[0058] Furthermore, the present inventors have demonstrated that the acidic reaction conditions in the gas-liquid contact apparatus are favorable for the reaction between the reducing agent and ozone, compared with the competitive reaction with oxygen. Experiment

[0059] The above ozone scrubber 10 equipped with a 10-stage column and having a total volume of about 2 L was installed. To the ozone scrubber, 180 g / m under standard temperature and standard pressure was fed from the gas inlet supply unit 31 3An inlet gas containing ozone was supplied at a rate of 200 L / h, and a sulfite aqueous solution with a concentration of 200 g / L and an alkaline pH of 8-10 was supplied from the new liquid supply unit 50. Pump 42 was started, and the reducing solution was recirculated at a flow rate of 25 L / h and a total volume of 5 L in the ozone scrubber 10. The pH was controlled to various values ​​by controlling the flow rate of the reducing solution in the new liquid supply unit 50. The gas outlet concentration was monitored to be less than 100 ppb, and the experiment was conducted at room temperature.

[0060] The consumption of the reducing agent was tracked at various pH concentrations, and the results are as follows:

[0061] [Table 1]

[0062] As a result, the lowest pH, i.e., 2.5, was the lowest, while alkaline conditions at pH=9 resulted in high and inefficient sulfite consumption.

[0063] Thus, the present invention makes it possible to decompose ozone by optimizing the use of reducing agents, and therefore limit the operating costs of this ozone scrubbing process.

[0064] Although the present invention has been described and illustrated in detail, this is merely illustrative and should not be interpreted as limiting, and it should be clearly understood that the scope of the present invention is limited only by the terminology of the appended claims.

Claims

1. A method for scrubbing ozone in an ozone scrubber (10) equipped with a gas-liquid contact device (20) adapted to bring an inlet gas containing ozone into contact with a reducing solution (15), The process of supplying the inlet gas to the gas-liquid contact device (20), A step of supplying a new reducing solution to the gas-liquid contact device (20), wherein the new reducing solution includes an aqueous solution of a reducing agent. A step of scrubbing the ozone in the inlet gas by a reduction reaction with the reducing solution under acidic pH conditions, The scrubbing process includes a step of recirculating at least a portion of the reducing solution (15) throughout the gas-liquid contact device (20), The reducing agent is selected such that an acidic reaction product is generated by the reduction reaction in the scrubbing step, and the acidic reaction product is recirculated throughout the gas-liquid contact device (20) in the scrubbing step to contribute to at least part of the acidic pH conditions. method.

2. The method for scrubbing ozone according to claim 1, wherein the reducing agent is based on a sulfur or phosphorus compound.

3. The method for scrubbing ozone according to claim 1 or 2, wherein the reducing agent comprises a sulfite, bisulfite, metabisulfite and / or thiosulfate.

4. A method for scrubbing ozone according to claim 2 and claims 2 to 3 as dependent on claim 2, comprising the step of supplying the new reducing solution into the gas-liquid contact device (20), and maintaining the acidic pH conditions inside the gas-liquid contact device (20) by controlling the flow rate of the new reducing solution.

5. The method for scrubbing ozone according to claim 4, wherein a constant pH is maintained during the step of maintaining the acidic pH conditions.

6. The method for scrubbing ozone according to any one of claims 1 to 5, wherein the acidic reaction product is sulfuric acid and / or sodium bisulfate.

7. The reduction reaction further generates oxidation reaction products, and the method, The process involves temporarily storing at least a portion of the reducing solution in the tank (30) or in the tank section of the gas-liquid contact device after the reduction reaction, A step of supplying fresh water into the tank (30) and / or the gas-liquid contact device (20), A step of discharging a portion of the reducing liquid (15) from the tank (30) or the tank section, A method for scrubbing ozone according to any one of claims 1 to 6, further comprising the step of controlling the concentration of the oxidation reaction product in the reducing solution (15) by acting on the flow rate of the supplied water and / or the discharged reducing solution.

8. A gas-liquid contact device (20), A gas inlet supply unit (31) adapted to supply the aforementioned inlet gas, An ozone scrubber (10) adapted to perform the ozone scrubbing method according to any one of claims 1 to 7, comprising a new liquid supply unit (50) adapted to supply the new reducing solution, An ozone scrubber (10) is provided with a recirculation means (40) configured to recirculate at least a portion of the reducing solution (15) to the entire gas-liquid contact device (20).

9. The ozone scrubber (10) according to claim 8, further comprising a pH control device (70) configured to maintain acidic pH conditions in the gas-liquid contact device (20) and / or the recirculation means (40) by controlling the flow rate of the new liquid supply unit (50).

10. The ozone scrubber (10) A tank (30) or the tank section of the gas-liquid contact device (20) is adapted to temporarily store the reducing solution (15) after circulation within the gas-liquid contact device (20) and before recirculation. A water supply unit (60) adapted to supply water into the gas-liquid contact device (20) or the tank (30), A liquid discharge section (32) adapted to discharge a portion of the reducing solution (15) from the tank (30) or the tank section, The ozone scrubber (10) according to claim 8 or 9, further comprising: a reaction product control device (80) adapted to control the concentration of oxidation reaction products in the reducing solution (15) by controlling the flow rate of the supplied water (60) and / or by controlling the flow rate of the discharged reducing solution (32).

11. The ozone scrubber (10) according to any one of claims 8 to 10, wherein the gas-liquid contact device (20) is a plate column.

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