JP5697545B2 - Method and apparatus for treating radioactive wastewater - Google Patents
Method and apparatus for treating radioactive wastewater Download PDFInfo
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Description
本発明は、放射性排水の処理方法及び処理装置に関するものである。 The present invention relates to a method and apparatus for treating radioactive waste water.
原子力施設から発生する放射性排水としては、作業員の衣類を洗濯した際に発生する洗濯排水、機器や配管系統の洗浄排水・ブロー排水などである機器ドレン水、施設床上への漏洩水・結露水や雑排水である床ドレン水などがある。これらの放射性排水は排水中の放射性物質を除去低減した上で、施設用水として再利用されたり、環境へ放出処分される。環境放流にあたっては、放射性物質以外にも排水中に含まれる化学的酸素要求量（以下ＣＯＤと略記）原因物質やノルマルヘキサン抽出物質（ノルマルヘキサンにより抽出される物質で主に油脂分）も除去低減する必要がある。 Radioactive wastewater generated from nuclear facilities includes laundry wastewater generated when workers' clothes are washed, equipment drain water such as washing wastewater and blow drainage for equipment and piping systems, and leaked water and condensed water on the facility floor. And floor drain water that is miscellaneous drainage. These radioactive wastewaters can be reused as facility water or disposed of to the environment after removing and reducing radioactive materials in the wastewater. In addition to radioactive substances, chemical oxygen demand (hereinafter abbreviated as COD) causing substances and normal hexane extract substances (substances extracted by normal hexane, mainly oils and fats) are removed and reduced in addition to radioactive substances. There is a need to.
本願出願人は、このようなＣＯＤ原因物質やノルマルヘキサン抽出物質を含有する放射性排水の処理技術に関し、図５に示す装置の反応槽１において、触媒存在下で、放射性排水と酸化剤とを接触させることにより、放射性排水中のイオン状放射性物質を酸化・不溶化処理すると同時に、ＣＯＤ原因物質・ノルマルヘキサン抽出物質を分解処理し、該処理水をフィルタ２で固液分離して不溶化された放射性物質を除去する技術を開示している（特許文献１）。 The applicant of the present application relates to the treatment technology of radioactive wastewater containing such COD-causing substances and normal hexane extract substances, and in the reaction tank 1 of the apparatus shown in FIG. 5 , the radioactive wastewater and the oxidizing agent are contacted in the presence of a catalyst. Oxidative and insolubilization treatment of ionic radioactive substances in radioactive wastewater, and at the same time, decompose COD causative substance and normal hexane extract, and separate the treated water into solid and liquid by filter 2 to insolubilize the radioactive substance Is disclosed (Patent Document 1).
酸化剤の中でも、特にオゾンは、強力な酸化剤として放射性排水中のＣＯＤ原因物質・ノルマルヘキサン抽出物質を分解する能力を有するため、当該観点からは酸化剤としてオゾンを選択することが好ましい。特許文献１の技術では、二酸化マンガン触媒との併用により、オゾンの酸化剤としての効力を更に強化して使用している。なお、放射性排水中のＣＯＤ原因物質・ノルマルヘキサン抽出物質の分解に伴いオゾンは消費・分解される。 Among oxidizers, ozone has a capability of decomposing COD-causing substances and normal hexane-extracted substances in radioactive wastewater as a powerful oxidizer, and therefore ozone is preferably selected as the oxidizer from this viewpoint. In the technique of Patent Document 1, the effect of ozone as an oxidizing agent is further enhanced by the combined use with a manganese dioxide catalyst. In addition, ozone is consumed and decomposed with decomposition of COD-causing substances and normal hexane extractable substances in radioactive wastewater.
しかし、余剰オゾンは依然排水中に残留しており、これらの余剰オゾンが、該装置の構造材に対して、強力な酸化剤として働くため、該構造材の腐食が懸念される。特に、洗濯排水中には、人体の汗に起因する塩素イオンが不可避的に含まれているため、該塩素イオンによって誘発される不動態皮膜の破壊によって、ＳＵＳ鋼の局部腐食（孔食、隙間腐食）が発生しやすくなっており、オゾンの存在下で、該腐食誘発傾向が大きくなっている問題がある。該構造材の腐食は、塩素イオン濃度、温度、pH等の環境条件に影響を受け、塩素イオン濃度が高く、温度が高く、pHが酸性に傾くほど、腐食傾向が強くなることが知られている。 However, surplus ozone still remains in the waste water, and these surplus ozone acts as a powerful oxidant for the structural material of the apparatus, so there is a concern about corrosion of the structural material. In particular, since the wash drainage inevitably contains chlorine ions caused by human sweat, local corrosion (pitting corrosion, gaps) of SUS steel is caused by the destruction of the passive film induced by the chlorine ions. Corrosion) is likely to occur, and there is a problem that the tendency to induce corrosion increases in the presence of ozone. It is known that the corrosion of the structural material is affected by environmental conditions such as chloride ion concentration, temperature, pH, etc., and the higher the chloride ion concentration, the higher the temperature, and the more acidic the pH, the stronger the corrosion tendency. Yes.
特許文献１の技術では、二酸化マンガン触媒を用いる場合、触媒活性を高めるために反応槽１の温度を３０℃〜８０℃程度、望ましくは５０℃〜７０℃程度とすることが好適であるとしており、高温条件となるため腐食の懸念が更に大きくなる問題がある。 In the technique of Patent Document 1, when a manganese dioxide catalyst is used, the temperature of the reaction vessel 1 is preferably about 30 ° C. to 80 ° C., preferably about 50 ° C. to 70 ° C. in order to increase the catalytic activity. However, there is a problem that the concern about corrosion is further increased because of high temperature conditions.
なお、腐食対策の観点から、構造材として一般的なステンレス鋼（SUS304、SUS316等）に変えて、上記のような環境下においても耐食性のある特殊な構造材であるチタンや高ニッケル合金（例、インコネル、ハステロイ等）を採用することは可能であり、特に、オゾンが供給されて高濃度のオゾンが存在する反応槽1においては、このような耐食性のある特殊な構造材を選定する必要がある。しかし、これらの特殊な構造材は非常に高価であるため、反応槽1の後段に配置されるすべての構造材をこれらに置き換えることは、コスト面から好ましくないという問題もあった。 In addition, from the viewpoint of corrosion countermeasures, instead of general stainless steel (SUS304, SUS316, etc.) as a structural material, titanium and high nickel alloys (examples of special structural materials that are corrosion resistant even in the above environment) Inconel, Hastelloy, etc.) can be used, and in particular, in the reaction tank 1 where ozone is supplied and high-concentration ozone exists, it is necessary to select such a special structural material having corrosion resistance. is there. However, since these special structural materials are very expensive, there is a problem that it is not preferable from the viewpoint of cost to replace all the structural materials arranged in the subsequent stage of the reaction tank 1 with these.
本発明の目的は前記の問題を解決し、塩素イオンを含有する放射性排水を、二酸化マンガン触媒存在下、該触媒の触媒活性が高くなる高温条件下でオゾン処理するに際し、構造材の腐食を、特殊な構造材への置き換えという高コストな手段によらず、効果的に回避可能とした技術を提供することである。 The object of the present invention is to solve the above-mentioned problem, and to treat the radioactive waste water containing chlorine ions in the presence of a manganese dioxide catalyst under high temperature conditions where the catalytic activity of the catalyst is high, It is to provide a technique that can be effectively avoided without using a high-cost means of replacement with a special structural material.
上記課題を解決するためになされた本発明の放射性排水の処理方法は、塩素イオンを含有する放射性排水を、３０℃〜８０℃で、二酸化マンガン触媒存在下でオゾンと接触させることにより、放射性排水中のイオン状放射性物質を酸化・不溶化処理すると同時に、化学的酸素要求量原因物質・ノルマルヘキサン抽出物質を分解処理するオゾン酸化処理工程と、オゾン酸化処理工程を経た処理水をフィルタで固液分離して不溶化された放射性物質を除去する固液分離工程を有する放射性排水の処理方法であって、該オゾン酸化処理工程と固液分離工程の中間工程として、該オゾン酸化処理工程で還元されず処理水に残留した余剰オゾンを自己分解により減衰させるための処理水滞留工程を有し、前記のオゾン酸化処理は、上部に、放射性排水を反応槽内に下降流で供給する排水供給部を設け、中段部に、オゾン含有ガスを上昇流で供給する散気管を設け、底部に、反応槽から放射性排水を後段に流出させる出口を設け、排水供給部と散気管との間に、二酸化マンガン触媒を配置するとともに、散気管と出口との間に、処理水に残留した余剰オゾンを自己分解により減衰させるための処理水滞留部を備えた反応槽で行い、該処理水滞留部において、余剰オゾンの濃度を経時的に、０．０１ｍｇ/Ｌ以下にまで、低下させることを特徴とするものである。 The method for treating radioactive wastewater of the present invention made to solve the above-mentioned problems is that radioactive wastewater containing chlorine ions is brought into contact with ozone in the presence of a manganese dioxide catalyst at 30 ° C to 80 ° C. Oxidation and insolubilization treatment of ionic radioactive substances in the substance, and at the same time, the ozone oxidation treatment process that decomposes the chemical oxygen demand cause substance and normal hexane extract material, and the treated water that passed through the ozone oxidation treatment process are separated into solid and liquid by a filter A method for treating radioactive wastewater having a solid-liquid separation step for removing insolubilized radioactive substances, and is not reduced in the ozone oxidation treatment step as an intermediate step between the ozone oxidation treatment step and the solid-liquid separation step the excess ozone remaining in water having a treated water retaining step for attenuating by autolysis ozone oxidation process of the are at the top, the radioactive waste water In the reaction tank, a drainage supply unit that supplies a downward flow is provided, an air diffuser that supplies an ozone-containing gas in an upward flow is provided in the middle stage, and an outlet that discharges radioactive wastewater from the reaction tank to the subsequent stage is provided in the bottom part. A manganese dioxide catalyst is arranged between the waste water supply unit and the diffuser pipe, and a treated water retention part for attenuating surplus ozone remaining in the treated water by self-decomposition is provided between the diffuser pipe and the outlet. It is carried out in a reaction tank, and the concentration of surplus ozone is lowered over time to 0.01 mg / L or less in the treated water retention part .
請求項２記載の発明は、請求項１記載の放射性排水の処理方法において、処理水滞留工程では、該オゾン酸化処理工程を経た処理水を０．５〜１時間滞留させることを特徴とするものである。 The invention according to claim 2 is characterized in that, in the treatment method of radioactive waste water according to claim 1, in the treated water retention step, the treated water that has passed through the ozone oxidation treatment step is retained for 0.5 to 1 hour. It is.
上記課題を解決するためになされた本発明の放射性排水の処理装置は、塩素イオンを含有する放射性排水を、３０℃〜８０℃で、二酸化マンガン触媒存在下でオゾンと接触させて、放射性排水中のイオン状放射性物質を酸化・不溶化処理すると同時に、化学的酸素要求量原因物質・ノルマルヘキサン抽出物質を分解処理するオゾン酸化処理する反応槽と、該反応槽の後段に設けた固液分離装置を備える放射性排水の処理装置であって、反応槽には、上部に、放射性排水を反応槽内に下降流で供給する排水供給部を設け、中段部に、オゾン含有ガスを上昇流で供給する散気管を設け、底部に、反応槽から放射性排水を後段に流出させる出口を設け、排水供給部と散気管との間に、二酸化マンガン触媒を配置するとともに、散気管と出口との間に、処理水に残留した余剰オゾンを自己分解により、０．０１ｍｇ/Ｌ以下にまで、減衰させるための処理水滞留部を備えることを特徴とするものである。 The radioactive wastewater treatment apparatus of the present invention, which has been made to solve the above-mentioned problems, brings radioactive wastewater containing chlorine ions into contact with ozone in the presence of a manganese dioxide catalyst at 30 ° C to 80 ° C. A reaction tank for the ozone oxidation treatment for decomposing the chemical oxygen demand causative substance and the normal hexane extract, and a solid-liquid separation device provided at the rear stage of the reaction tank. The wastewater treatment apparatus is provided with a wastewater supply section for supplying radioactive wastewater in a downward flow into the reaction tank at the top, and a dispersion tank for supplying ozone-containing gas in an upward flow to the middle section. A trachea is provided, and an outlet is provided at the bottom to allow radioactive wastewater to flow out from the reaction tank to the subsequent stage. A manganese dioxide catalyst is disposed between the drainage supply unit and the aeration pipe, and between the aeration pipe and the outlet. The self-decomposition of excess ozone remaining in the treated water, to below 0.01 mg / L, and is characterized in further comprising a treated water retention portion for damping.
本発明に係る放射性排水の処理方法は、塩素イオンを含有する放射性排水を、二酸化マンガン触媒存在下でオゾンと接触させることにより、放射性排水中のイオン状放射性物質を酸化・不溶化処理すると同時に、ＣＯＤ原因物質・ノルマルヘキサン抽出物質を分解処理するオゾン酸化処理工程と、オゾン酸化処理工程を経た処理水をフィルタで固液分離して不溶化された放射性物質を除去する固液分離工程を有する放射性排水の処理方法であって、該オゾン酸化処理工程と固液分離工程の中間工程として、該オゾン酸化処理工程で還元されず処理水に残留した余剰オゾンを自己分解により減衰させるための処理水滞留工程を有し、前記のオゾン酸化処理は、上部に、放射性排水を反応槽内に下降流で供給する排水供給部を設け、中段部に、オゾン含有ガスを上昇流で供給する散気管を設け、底部に、反応槽から放射性排水を後段に流出させる出口を設け、排水供給部と散気管との間に、二酸化マンガン触媒を配置するとともに、散気管と出口との間に、処理水に残留した余剰オゾンを自己分解により減衰させるための処理水滞留部を備えた反応槽で行い、該処理水滞留部において、余剰オゾンの濃度を経時的に、０．０１ｍｇ/Ｌ以下にまで、低下させる構成により、固液分離工程以降の処理水に含有されるオゾン量を確実に低減することができる。このため、「塩素イオンを含有する放射性排水を、二酸化マンガン触媒存在下、該触媒の触媒活性が高くなる高温条件下でオゾン処理する」という、構造材の腐食を誘発しやすい環境条件下においても、少なくとも、固液分離工程以降の工程を構成する構造材に関しては、上記環境条件に対しても耐食性のある特殊な構造材への置き換えという高コストな手段によらず、構造材の腐食を効果的に回避することができる。 In the method for treating radioactive waste water according to the present invention, the radioactive waste water containing chlorine ions is contacted with ozone in the presence of a manganese dioxide catalyst to oxidize / insolubilize the ionic radioactive material in the radioactive waste water, and at the same time, COD Radioactive wastewater that has an ozone oxidation process that decomposes the causative substance and normal hexane extract, and a solid-liquid separation process that removes insolubilized radioactive substances by separating the treated water that has passed through the ozone oxidation process with a filter. In the treatment method, as an intermediate step between the ozone oxidation treatment step and the solid-liquid separation step, a treatment water retention step for attenuating excess ozone remaining in the treatment water without being reduced in the ozone oxidation treatment step by self-decomposition have the ozone oxidation process of the upper part, a drainage supply section for supplying downflow provided radioactive waste water into the reaction vessel, the middle portion, Oh A gas diffuser pipe is provided to supply the hydrogen-containing gas in an upward flow, an outlet is provided at the bottom to allow radioactive wastewater to flow out from the reaction tank to the subsequent stage, and a manganese dioxide catalyst is disposed between the wastewater supply part and the gas diffuser pipe. Between the aeration tube and the outlet, it is carried out in a reaction tank equipped with a treated water retention part for attenuating surplus ozone remaining in the treated water by self-decomposition. In addition, the amount of ozone contained in the treated water after the solid-liquid separation step can be reliably reduced by the configuration in which the amount is reduced to 0.01 mg / L or less . For this reason, even under environmental conditions that easily induce corrosion of structural materials, such as "treatment of radioactive wastewater containing chlorine ions in the presence of a manganese dioxide catalyst under high temperature conditions where the catalytic activity of the catalyst is high". However, at least for structural materials that comprise the steps after the solid-liquid separation step, corrosion of the structural materials is effective regardless of the above-mentioned environmental conditions, regardless of expensive means of replacement with special structural materials that have corrosion resistance. Can be avoided.
以下に本発明の好ましい実施形態を示す。
（第１の実施形態）
図１には、第１の実施形態を説明するブロック図を示している。
第１の実施形態は、塩素イオンを含有する放射性排水を、二酸化マンガン触媒存在下でオゾンと接触させることにより、放射性排水中のイオン状放射性物質を酸化・不溶化処理すると同時に、ＣＯＤ原因物質・ノルマルヘキサン抽出物質を分解処理するオゾン酸化処理工程と、オゾン酸化処理工程を経た処理水をフィルタで固液分離して不溶化された放射性物質を除去する固液分離工程を有する放射性排水の処理方法において、該オゾン酸化処理工程と固液分離工程の中間工程として、該オゾン酸化処理工程で還元されず処理水に残留した余剰オゾンを自己分解により減衰させるための処理水滞留工程を有するものである。
Preferred embodiments of the present invention are shown below.
(First embodiment)
FIG. 1 is a block diagram for explaining the first embodiment.
In the first embodiment, radioactive effluent containing chlorine ions is brought into contact with ozone in the presence of a manganese dioxide catalyst to oxidize / insolubilize ionic radioactive substances in the radioactive effluent, and at the same time, COD causative substances / normal In a treatment method of radioactive wastewater having an ozone oxidation treatment step for decomposing hexane extractant and a solid-liquid separation step for removing insolubilized radioactive material by solid-liquid separation of the treated water through the ozone oxidation treatment step with a filter, As an intermediate step between the ozone oxidation treatment step and the solid-liquid separation step, there is a treatment water retention step for attenuating excess ozone remaining in the treatment water without being reduced in the ozone oxidation treatment step by self-decomposition.
本実施形態は、オゾンが自己分解（２Ｏ３→３Ｏ２）して減衰する特性を利用したものである。なお、オゾンの自己分解反応速度に関し、気相中に比べて、液相中では圧倒的に短時間でオゾン分解が進むことや、液相中におけるオゾンの自己分解反応速度は、温度が高いほど、ｐＨがアルカリに傾くほど、早くなることも知られている。 The present embodiment utilizes the characteristic that ozone is self-decomposed (2O 3 → 3O 2 ) and attenuates. Regarding the rate of ozone self-decomposition, compared to the gas phase, ozone decomposition proceeds in an overwhelmingly short time in the liquid phase, and the ozone self-decomposition reaction rate in the liquid phase increases as the temperature increases. It is also known that the faster the pH is inclined to alkali, the faster.
図１に示すように、反応槽1の上部からは放射性排水が下降流で供給され、反応槽1の中段部からはオゾン含有ガスが上昇流で供給される。反応槽1内に設けた触媒層５の気液混相内でＣＯＤ原因物質・ノルマルヘキサン抽出物質が酸化分解された後、反応層1の下部に処理液として取り出され、後段（循環タンク４）へ送られる。反応槽1のオゾンガス散気管（酸化剤供給手段６）の近傍では液中のオゾンは溶解度に達していると考えられるが、散気管下部から反応槽1出口に至るまでの間に、反応槽滞留水量にリンクした時間遅れが生じ、この間オゾンは自己分解を起こし濃度が経時的に低下していく。 As shown in FIG. 1, radioactive waste water is supplied in a downward flow from the upper part of the reaction tank 1, and ozone-containing gas is supplied in an upward flow from the middle part of the reaction tank 1. After the COD-causing substance / normal hexane extract substance is oxidatively decomposed in the gas-liquid mixed phase of the catalyst layer 5 provided in the reaction tank 1, it is taken out as a processing liquid to the lower part of the reaction layer 1 to the subsequent stage (circulation tank 4) Sent. In the vicinity of the ozone gas diffuser pipe (oxidant supply means 6) of the reaction tank 1, it is considered that the ozone in the liquid has reached the solubility, but the reaction tank stays between the lower part of the diffuser pipe and the outlet of the reaction tank 1. There is a time delay linked to the amount of water. During this time, ozone undergoes autolysis and the concentration decreases over time.
図１に示す実施形態においては、滞留時間を確保する手段として、反応槽1高さを高くし、散気管６より下部の容量を増やし、反応槽1下部の処理水滞留部８における滞留時間を延長することで、後段設備へ影響を及ぼさないレベルまでオゾンを減衰させている。なお従来技術では、図５に示すように、反応槽１出口は散気管６より上部に配置されていたが、本実施形態では、反応槽1出口を散気管６より下部に配置している。 In the embodiment shown in FIG. 1, as means for ensuring the residence time, the height of the reaction tank 1 is increased, the capacity below the diffuser tube 6 is increased, and the residence time in the treated water retention section 8 at the lower part of the reaction tank 1 is set. By extending, ozone is attenuated to a level that does not affect the subsequent equipment. In the prior art, as shown in FIG. 5 , the outlet of the reaction tank 1 is arranged above the diffuser tube 6, but in this embodiment, the outlet of the reaction tank 1 is arranged below the diffuser pipe 6.
反応槽1から後段の循環タンク４への導水管は、反応槽1の水位まで立ち上げている。反応槽1へ供給された放射性排水は、この立ち上げた導水管を通過して後段の循環タンク４へ移送されている。 The water conduit from the reaction tank 1 to the subsequent circulation tank 4 is raised to the water level of the reaction tank 1. The radioactive wastewater supplied to the reaction tank 1 passes through the water pipe that has been started up and is transferred to the subsequent circulation tank 4.
循環タンク４以降は、循環ポンプ３及びフィルタ２から構成されたろ過システムで放射性排水が循環している。循環ポンプ及びフィルタ収納容器は構造も複雑となるため、当該部分に滞留時間を確保するための設計変更を加えることは困難を伴う。 After the circulation tank 4, radioactive waste water is circulated by a filtration system composed of a circulation pump 3 and a filter 2. Since the structure of the circulation pump and the filter storage container is complicated, it is difficult to make a design change for securing the residence time in the part.
（第２の実施形態）
図２には、第２の実施形態を説明するブロック図を示している。
第２の実施形態は、塩素イオンを含有する放射性排水を、二酸化マンガン触媒存在下でオゾンと接触させることにより、放射性排水中のイオン状放射性物質を酸化・不溶化処理すると同時に、ＣＯＤ原因物質・ノルマルヘキサン抽出物質を分解処理するオゾン酸化処理工程と、オゾン酸化処理工程を経た処理水をフィルタで固液分離して不溶化された放射性物質を除去する固液分離工程を有する放射性排水の処理方法において、該オゾン酸化処理工程と固液分離工程の中間工程として、該オゾン酸化処理工程で還元されず処理水に残留した余剰オゾンを自己分解により減衰させるための処理水滞留工程および該オゾン酸化処理工程で還元されず処理水に残留した余剰オゾンを液相から気相に追い出すバブリング工程を有するものである。
(Second Embodiment)
FIG. 2 is a block diagram for explaining the second embodiment.
In the second embodiment, radioactive effluent containing chlorine ions is brought into contact with ozone in the presence of a manganese dioxide catalyst to oxidize / insolubilize the ionic radioactive substance in the radioactive effluent, and at the same time, COD causative substance / normal In a treatment method of radioactive wastewater having an ozone oxidation treatment step for decomposing hexane extractant and a solid-liquid separation step for removing insolubilized radioactive material by solid-liquid separation of the treated water through the ozone oxidation treatment step with a filter, As an intermediate step between the ozone oxidation treatment step and the solid-liquid separation step, in the treated water retention step and the ozone oxidation treatment step for attenuating excess ozone remaining in the treated water without being reduced in the ozone oxidation treatment step by self-decomposition It has a bubbling process in which surplus ozone remaining in the treated water that has not been reduced is expelled from the liquid phase to the gas phase.
本実施形態は、第１の実施形態で説明したオゾンの自己分解に加え、気相への空気吹き込み（バブリング）を行い、気液平衡によりオゾンを気相側に追い出すことによって、液中オゾン量を減衰させるものである。 In the present embodiment, in addition to the self-decomposition of ozone described in the first embodiment, air is blown into the gas phase (bubbling), and ozone is expelled to the gas phase side by gas-liquid equilibrium. Is attenuated.
バブリング手段としては、図２に示すように、反応槽1から後段の循環タンク４への導水管に空気を吹き込む方法を採用することもできる。 As the bubbling means, as shown in FIG. 2 , a method of blowing air from the reaction tank 1 to the water conduit to the subsequent circulation tank 4 may be employed.
（滞留時間と余剰オゾンの減衰に関する試験）
放射性排水（ここでは洗濯排水に着目）を模擬するため、洗剤、油脂及び蛋白質等を調合した模擬排水を調整した。排水中の含有成分によりオゾンの自己分解が促進されると想定されるので、比較のため水でも実施した。
(Residence time and excess ozone decay test)
In order to simulate radioactive wastewater (here, focus on laundry wastewater), simulated wastewater prepared by mixing detergent, fats and oils, and the like was prepared. Since it is assumed that the self-decomposition of ozone is promoted by the components contained in the wastewater, it was also carried out with water for comparison.
図３に示す装置を使用し、この模擬排水又は水を、触媒充填部□１００ｍｍ、高さ４ｍの反応塔にＳＶ＝０．６７５〜０．９（約２７〜３６リットル/ｈ）で塔上部より供給し、また触媒充填部下部より７％程度のオゾンガスを含有した空気を通気し、塔内へ散気した。触媒はハニカム充填物の表面に二酸化マンガンを担持させた二酸化マンガン触媒で、反応塔内部を７０℃に加温した。オゾン供給量は模擬排水に対して１３５０〜１４８５ｐｐｍとした。 Using the apparatus shown in FIG. 3 , this simulated waste water or water is placed in the catalyst filling section □ 100 mm and the height of 4 m in the reaction tower at SV = 0.675 to 0.9 (about 27 to 36 liters / h). Further, air containing about 7% ozone gas was vented from the lower part of the catalyst packed part and diffused into the tower. The catalyst was a manganese dioxide catalyst in which manganese dioxide was supported on the surface of the honeycomb packing, and the inside of the reaction tower was heated to 70 ° C. The ozone supply amount was 1350 to 1485 ppm with respect to the simulated waste water.
処理水は、塔下部のオゾン散気部を通過し、塔底より排出した。オゾン散気部から塔底までの間にサンプリングラインを設け、処理水の溶存オゾン濃度を測定し、触媒充填塔下部内の滞留時間に対するオゾン自己減衰を確認した。 The treated water passed through the ozone diffuser at the bottom of the tower and was discharged from the bottom of the tower. A sampling line was provided between the ozone diffuser and the tower bottom, the dissolved ozone concentration of the treated water was measured, and ozone self-attenuation with respect to the residence time in the lower part of the catalyst packed tower was confirmed.
図４に示すように、触媒充填塔下部の滞留時間の増加に伴い、溶存オゾン濃度は減少し、溶存オゾンの減衰を確認した。滞留時間０．５ｈ以上で溶存オゾン濃度は検出限界値以下（０．０１ｍｇ/リットル）となった。以上の結果より、触媒充填塔内のオゾン散気部以降に１ｈの滞留時間を確保することで、処理水中に溶存・残留した余剰オゾンを減衰できることが確認された。 As shown in FIG. 4 , with the increase of the residence time at the lower part of the catalyst packed tower, the dissolved ozone concentration decreased, and attenuation of the dissolved ozone was confirmed. At a residence time of 0.5 h or longer, the dissolved ozone concentration was below the detection limit (0.01 mg / liter). From the above results, it was confirmed that the excess ozone dissolved and remaining in the treated water can be attenuated by securing a residence time of 1 h after the ozone diffuser in the catalyst packed tower.
１ 反応槽
２ フィルタ
３ 循環ポンプ
４ 循環タンク
５ 触媒
６ 酸化剤供給手段
８ 処理水滞留部
９ 空気供給手段
DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Filter 3 Circulation pump 4 Circulation tank 5 Catalyst 6 Oxidant supply means 8 Treated water retention part 9 Air supply means
Claims (3)
該オゾン酸化処理工程と固液分離工程の中間工程として、該オゾン酸化処理工程で還元されず処理水に残留した余剰オゾンを自己分解により減衰させるための処理水滞留工程を有し、
前記のオゾン酸化処理は、上部に、放射性排水を反応槽内に下降流で供給する排水供給部を設け、中段部に、オゾン含有ガスを上昇流で供給する散気管を設け、底部に、反応槽から放射性排水を後段に流出させる出口を設け、排水供給部と散気管との間に、二酸化マンガン触媒を配置するとともに、散気管と出口との間に、処理水に残留した余剰オゾンを自己分解により減衰させるための処理水滞留部を備えた反応槽で行い、該処理水滞留部において、余剰オゾンの濃度を経時的に、０．０１ｍｇ/Ｌ以下にまで、低下させることを特徴とする放射性排水の処理方法。 Chemical oxygen demand at the same time as oxidizing and insolubilizing ionic radioactive materials in radioactive wastewater by contacting radioactive wastewater containing chloride ions with ozone in the presence of manganese dioxide catalyst at 30-80 ℃ Radioactive wastewater that has an ozone oxidation process that decomposes the causative substance and normal hexane extract, and a solid-liquid separation process that removes insolubilized radioactive substances by separating the treated water that has passed through the ozone oxidation process with a filter. A processing method,
As an intermediate step between the ozone oxidation treatment step and the solid-liquid separation step, there is a treatment water retention step for attenuating excess ozone remaining in the treatment water without being reduced in the ozone oxidation treatment step by self-decomposition,
In the ozone oxidation treatment, a drainage supply unit that supplies radioactive wastewater in a downward flow into the reaction tank is provided at the top, an air diffuser that supplies ozone-containing gas in an upward flow is provided in the middle stage, and a reaction is performed at the bottom. An outlet for discharging the radioactive wastewater from the tank to the latter stage is provided, and a manganese dioxide catalyst is placed between the drainage supply section and the diffuser pipe, and excess ozone remaining in the treated water is self-exposed between the diffuser pipe and the outlet. It is carried out in a reaction tank equipped with a treated water retention part for attenuation by decomposition, and in the treated water retention part, the concentration of surplus ozone is lowered over time to 0.01 mg / L or less. Radioactive wastewater treatment method.
反応槽には、In the reaction tank,
上部に、放射性排水を反応槽内に下降流で供給する排水供給部を設け、In the upper part, a waste water supply part for supplying radioactive waste water in a downward flow into the reaction tank is provided,
中段部に、オゾン含有ガスを上昇流で供給する散気管を設け、In the middle part, an air diffuser that supplies ozone-containing gas in an upward flow is installed.
底部に、反応槽から放射性排水を後段に流出させる出口を設け、At the bottom, there is an outlet that allows the radioactive wastewater to flow out from the reaction tank to the subsequent stage,
排水供給部と散気管との間に、二酸化マンガン触媒を配置するとともに、A manganese dioxide catalyst is placed between the waste water supply section and the air diffuser,
散気管と出口との間に、処理水に残留した余剰オゾンを自己分解により、０．０１ｍｇ/Ｌ以下にまで、減衰させるための処理水滞留部を備えることを特徴とする放射性排水の処理装置。A treatment apparatus for radioactive waste water, comprising a treated water retention part for attenuating excess ozone remaining in treated water to 0.01 mg / L or less between the air diffuser and the outlet by self-decomposition .
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