JP3759930B2 - Waste liquid treatment method and apparatus - Google Patents
Waste liquid treatment method and apparatus Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、原子炉等で発生する廃液中の６価クロムを３価クロムに還元することにより無毒化する廃液の処理方法および装置に関する。
【０００２】
【従来の技術】
従来、原子炉等で発生する、たとえば遮蔽冷却水等の廃液中に含まれる６価クロムを３価クロムに還元処理する方法は、下記特許文献１および２に記載されているように、還元剤として亜硫酸水素ナトリウム、硫酸第一鉄または過酸化水素を添加する方法が考案されている。
【０００３】
【特許文献１】
特開平９−２０６７６３号公報
【特許文献２】
特開２００１−１２１１６２公報
【０００４】
【発明が解決しようとする課題】
上記の亜硫酸水素ナトリウム等の還元剤により６価クロムを３価クロムに還元する場合、ｐＨ調整剤として予め硫酸などの無機酸を添加し、廃液を酸性状態にする必要がある。この方法によれば還元反応は確実に起こるが、還元剤およびｐＨ調整剤が廃棄物となるため、還元処理に伴う二次廃棄物発生量が増加するという問題がある。
そこで本発明は、二次廃棄物発生量が少なく、しかも作業環境性の良い廃液の処理方法および装置を提供することを目的とする。
【０００５】
【課題を解決するための手段】
上記課題を解決するために、請求項１の発明は、６価クロムを含む廃液の処理方法において、前記廃液にｐＨ調整剤としてギ酸を添加し、還元剤として過酸化水素を添加して、６価クロムを３価クロムに還元し、ギ酸を炭酸ガスと水に分解する構成とする。
請求項２の発明は、前記廃液に残留する過酸化水素を紫外線により酸素ガスと水に分解する構成とする。
【０００６】
請求項３の発明は、前記廃液中に過酸化水素が残留していない状態になった後に、前記３価クロムをカチオン樹脂で廃液から分離する構成とする。
請求項４の発明は、前記廃液中に過酸化水素およびギ酸が残留していない状態になった後に、カチオン樹脂とアニオン樹脂により前記廃液を浄化する構成とする。
【０００７】
請求項５の発明は、６価クロムを含む廃液が流れる流路に接続されたギ酸注入部、過酸化水素注入部、紫外線照射部およびイオン交換樹脂塔を備え、前記紫外線照射部は前記イオン交換樹脂塔の上流側に接続されている構成とする。
【０００８】
【発明の実施の形態】
本発明は、廃液のｐＨ調整剤にギ酸を、還元剤に過酸化水素を適用することを特徴としている。廃液のｐＨが中性からアルカリ性では、６価クロムはクロム酸イオン（CrO4 2-）として存在する。クロム酸イオンは酸化力が弱いため、ギ酸を添加してｐＨを酸性にし、酸化力が強い二クロム酸イオン（Cr2O7 2-）に変換する。この状態で過酸化水素を添加すると、過酸化水素の還元力で二クロム酸イオンの６価クロムは３価クロムに還元される。
【０００９】
過酸化水素は相手の酸化力により還元剤あるいは酸化剤として作用する。ｐＨ調整剤として添加したギ酸に対しては酸化剤として作用し、ギ酸は炭酸ガスと水に分解される。
このように本発明による６価クロムの還元方法では、ギ酸は炭酸ガスと水に、過酸化水素は水に分解されるため、還元処理に伴う二次廃棄物量を大幅に低減できる。
【００１０】
また、還元処理過程において、３価クロムはカチオン樹脂で分離して廃液からクロムを除去し、ギ酸分解後はカチオン樹脂とアニオン樹脂によりその他の金属イオンおよび有機物を除去することにより廃液を浄化することができる。
【００１１】
図１は本発明の実施の形態の廃液の処理装置を示す図である。処理装置は、６価クロムが溶解した廃液１を貯留した貯留槽２と、廃液１を循環するための循環ライン３を備え、循環ライン３には、上流側から順に、ギ酸注入部４、過酸化水素注入部５、循環ポンプ６、ヒーター７、紫外線照射部８が接続され、紫外線照射部８の下流側にはカチオン樹脂塔９およびアニオン樹脂塔１０が並列に接続されている。また、貯留槽２の上部には廃液１から発生するガスや蒸気を排出するための排気ライン１１が接続されている。なお、状況によっては、貯蔵槽２から循環ライン３の代りに一方向に１回流れる直列の流路としてもよく、さらには貯蔵槽２を削除した直列の流路の形としてもよい。
【００１２】
図１に示した装置を用いて廃液１中の６価クロムを還元する方法は下記のように行う。廃液１のｐＨが中性からアルカリ性では下記(1)式に示すように６価クロム(Cr6+)はクロム酸イオン(CrO4 2-)として存在する。このイオンは酸化還元電位が小さいため酸化力が弱い。
CrO4 2- + 4H2O + 3e- = Cr(OH)3 + 5OH- E゜ = - 0.13V …(1)
【００１３】
そこで、通常はｐＨ調整剤として硫酸などの無機酸を添加して、(2)式に示す酸化力の強い二クロム酸イオンを生成し、還元剤を添加して６価クロムを３価クロム［Cr3+］に還元している。
Cr2O7 2- + 14H+ + 6e- = 2Cr3+ + 7H2O E゜ = + 1.33V …(2)
【００１４】
本発明は、ｐＨ調整剤として従来の無機酸の代わりに、炭酸ガスと水に分解可能なギ酸を用いることが特徴である。実施例として例えば、金属製品の防錆塗料に含まれるクロム酸カリウム［K2CrO4］を処理する場合について説明する。クロム酸カリウムが溶解した廃液１中に、ギ酸［HCOOH］を添加すると(3)式に示すように二クロム酸が生成する。
2K2CrO4 + 4HCOOH = H2Cr2O7 + 4KCOOH +H2O …(3)
【００１５】
次に、この廃液１に過酸化水素注入部５から過酸化水素［H2O2］を添加すると(4)式に示す反応により二クロム酸の６価クロムは３価クロムに還元される。
H2Cr2O7 + 6HCOOH + H2O2 = 2Cr(COOH)3 + 2O2 + 5H2O …(4)
【００１６】
次に廃液１をカチオン樹脂塔９に通水すると、３価クロムおよびカリウムイオン［K+］は(5)、(6)式の反応によりカチオン樹脂に吸着され、廃液１からクロムイオンおよびカリウムイオンが除去される。
3R-SO3H + Cr(COOH)3 = (R-SO3)3Cr + 3HCOOH …(5)
R-SO3H + KCOOH = R-SO3K + HCOOH …(6)
【００１７】
一方、過酸化水素は(7)、(8)式に示すように相手の酸化還元電位によって還元剤または酸化剤として作用する。
H2O2 → O2 + 2H+ + 2e- E゜ = - 0.68V …(7）
H2O2 + 2H+ + 2e- → 2H2O E゜ = 1.77V …(8）
したがって、過酸化水素はギ酸に対して酸化剤として作用し、(9)式に示す反応によりギ酸は炭酸ガス［CO2］と水に分解される。
【００１８】
HCOOH + H2O2 = CO2 + 2H2O …(9)
【００１９】
なお、廃液１中に過酸化水素が残留した状態でカチオン樹脂塔９に通水すると、過酸化水素の酸化力で樹脂が劣化し、交換容量が低下する。樹脂の劣化を防止するため、紫外線照射部８から流通する廃液１に紫外線を照射し、廃液１に残留する過酸化水素を酸素ガスと水に分解する。廃液１から過酸化水素が無くなった時点でカチオン樹脂塔９に廃液を通水する。
【００２０】
以上のように、６価クロムの還元処理に添加したギ酸および過酸化水素は炭酸ガス、酸素ガスおよび水に分解されるため、還元処理に伴う二次廃棄物量を大幅に低減することができる。
【００２１】
次に上記(4)〜(6)、(9)の反応を確認するため、廃液１の処理前および処理後にクロム、カリウムおよび有機炭素（TOC）を測定した結果を図２に示す。処理前の廃液１中にはクロムが78ppm、カリウムが110ppm溶解していた。この廃液にギ酸を2000ppm添加し、過酸化水素で６価クロムを３価クロムに還元して、３価クロムおよびカリウムイオンをカチオン樹脂で除去した。その結果、廃液１中のクロムイオンおよびカリウムイオンは検出限界値以下となる0.5ppm以下まで低下した。また、ギ酸の存在を示す有機炭素（TOC）の濃度は試験前に約520ppmであったが、過酸化水素により炭酸ガスと水に分解することにより検出限界値以下となる１ppm以下まで低下した。
なお、ギ酸の分解速度は、温度が高いほど速いため、短時間にギ酸を分解する場合は、ヒーター７により廃液１の温度を50℃以上に昇温する。
【００２２】
ギ酸分解終了後は、廃液１をカチオン樹脂塔９とアニオン樹脂塔１０に通水してその他の金属イオンおよび有機物を除去する。浄化した廃液を放流する場合は、排水基準値以下であることを確認後に排出する。
【００２３】
次に本発明と従来法による６価クロムの還元処理に伴う二次廃棄物発生量を試算した結果を説明する。二次廃棄物発生量の試算条件は、処理物が二クロム酸カリウム、クロム濃度が200ppm、廃液量が100m3である。処理方法は、本発明および従来法ともｐＨ調整→還元処理→中和処理の手順で実施した。
【００２４】
従来法は亜硫酸水素ナトリウムで還元処理した場合で説明する。クロム酸カリウムが溶解した廃液に硫酸［H2SO4］を添加し、(10)式に示すように二クロム酸を生成させる。
2K2CrO4 + 2H2SO4 = H2Cr2O7 + 2K2SO4 + H2O …(10)
【００２５】
亜硫酸水素ナトリウム［NaHSO3］を添加して(11)式に示すように６価クロムを３価クロムに還元する。
2H2Cr2O7 + 6NaHSO3 + 3H2SO4 = 2Cr2(SO4)3 + 3Na 2 SO 4 + 8H2O …(11)
【００２６】
水酸化ナトリウム［NaOH］を添加して(12)、(13)式に示すように水酸化クロム［Cr(OH)3］、水酸化カリウム［KOH］および硫酸ナトリウム［Na2SO4］を生成する。
Cr2(SO4)3 + 6NaOH = 2Cr(OH) 3 + 3Na 2 SO 4 …(12)
K2SO4 + 2NaOH = 2KOH + Na 2 SO 4 …(13)
【００２７】
したがって、従来法では(11)〜(13)式の下線で示した水酸化クロム、水酸化カリウムおよび硫酸ナトリウムが二次廃棄物となる。
一方、本発明の還元処理では(4)式のようにギ酸でｐＨ調整を行う。その後に(14)、(15)式に示すように過酸化水素を添加してギ酸を分解する。
Cr(COOH)3 + 3H2O2 = Cr(OH)3 + 3CO2 + 3H2O …(14)
KCOOH + H2O2 = KOH + CO2 + H2O …(15)
【００２８】
したがって、本発明で発生する二次廃棄物は水酸化クロム、水酸化カリウムのみである。
本発明と従来法の二次廃棄物を試算した結果を図３に示す。図から明らかなように、本発明ではクロム酸カリウムから起因する廃棄物量のみであるが、従来法は中和処理後に発生する硫酸ナトリウムが加算される。したがって、本発明の廃棄物発生量は従来法の１／３程度である。
【００２９】
以上のように、本発明では廃液のｐＨ調整剤として炭酸ガスと水に分解できるギ酸を使用するため、廃棄物発生量を大幅に低減することができる。
また、従来法では還元処理したあとに中和処理を行っているが、中和処理で発生する沈殿物と上澄み液とを分離し、沈殿物は回収して処分されている。多量の廃液を処理するためには大規模な装置が必要となり、しかもｐＨ調整や沈殿物の取扱などの操作が煩雑である。
【００３０】
一方、本発明では還元処理後およびギ酸分解後の廃液はイオン交換樹脂で浄化するため、装置構成が非常に簡単で、しかも沈殿物の取扱が無いため作業環境が大幅に改善される。
【００３１】
【発明の効果】
本発明によれば、二次廃棄物発生量が少なく、しかも作業環境性の良い廃液の処理方法および装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態の廃液の処理装置の系統図。
【図２】カチオン樹脂により廃液からクロムおよびカリウムを除去した結果と、過酸化水素によりギ酸の有機炭素を分解した結果を示し、本発明の効果を説明する棒グラフ。
【図３】本発明の方法と従来の方法による二次廃棄物発生量を試算した結果を示し、本発明の効果を説明する棒グラフ。
【符号の説明】
１…廃液、２…貯留槽、３…循環ライン、４…ギ酸注入部、５…過酸化水素注入部、６…循環ポンプ、７…ヒーター、８…紫外線照射部、９…カチオン樹脂塔、１０…アニオン樹脂塔、１１…排気ライン。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a waste liquid treatment method and apparatus for detoxification by reducing hexavalent chromium in waste liquid generated in a nuclear reactor or the like to trivalent chromium.
[0002]
[Prior art]
Conventionally, a method of reducing hexavalent chromium, which is generated in a nuclear reactor or the like and contained in a waste liquid such as shielding cooling water, to trivalent chromium, is described in Patent Documents 1 and 2 below. A method of adding sodium bisulfite, ferrous sulfate or hydrogen peroxide has been devised.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-206763 [Patent Document 2]
[Patent Document 1] Japanese Patent Laid-Open No. 2001-121162
[Problems to be solved by the invention]
When hexavalent chromium is reduced to trivalent chromium with a reducing agent such as sodium hydrogen sulfite, it is necessary to add an inorganic acid such as sulfuric acid in advance as a pH adjuster to make the waste liquid acidic. According to this method, the reduction reaction occurs reliably, but since the reducing agent and the pH adjuster become waste, there is a problem that the amount of secondary waste generated in the reduction treatment increases.
SUMMARY OF THE INVENTION An object of the present invention is to provide a waste liquid treatment method and apparatus that generate a small amount of secondary waste and that have a good work environment.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the invention of claim 1 is directed to a method for treating a waste liquid containing hexavalent chromium, wherein formic acid is added to the waste liquid as a pH adjuster and hydrogen peroxide is added as a reducing agent. The structure is such that the valent chromium is reduced to trivalent chromium and the formic acid is decomposed into carbon dioxide gas and water.
According to a second aspect of the invention, hydrogen peroxide remaining in the waste liquid is decomposed into oxygen gas and water by ultraviolet rays .
[0006]
According to a third aspect of the present invention, the trivalent chromium is separated from the waste liquid with a cationic resin after hydrogen peroxide is not left in the waste liquid .
According to a fourth aspect of the present invention, the waste liquid is purified by a cation resin and an anion resin after hydrogen peroxide and formic acid are not left in the waste liquid .
[0007]
The invention of claim 5 comprises a formic acid injection part, a hydrogen peroxide injection part, an ultraviolet irradiation part and an ion exchange resin tower connected to a flow path through which a waste liquid containing hexavalent chromium flows , wherein the ultraviolet irradiation part is the ion exchange The structure is connected to the upstream side of the resin tower .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is characterized in that formic acid is applied as a pH adjuster for waste liquid and hydrogen peroxide is applied as a reducing agent. When the pH of the waste liquid is neutral to alkaline, hexavalent chromium exists as chromate ions (CrO 4 2− ). Since chromate ions have weak oxidizing power, formic acid is added to make the pH acidic, and it is converted to dichromate ions (Cr 2 O 7 2− ) having strong oxidizing power. When hydrogen peroxide is added in this state, hexavalent chromium of dichromate ions is reduced to trivalent chromium by the reducing power of hydrogen peroxide.
[0009]
Hydrogen peroxide acts as a reducing agent or an oxidizing agent depending on the oxidizing power of the partner. Formic acid added as a pH adjuster acts as an oxidizing agent, and formic acid is decomposed into carbon dioxide gas and water.
Thus, in the method for reducing hexavalent chromium according to the present invention, formic acid is decomposed into carbon dioxide gas and water, and hydrogen peroxide is decomposed into water, so that the amount of secondary waste accompanying the reduction treatment can be greatly reduced.
[0010]
In the reduction process, trivalent chromium is separated from the waste liquid by cation resin, and after removal of formic acid, the waste liquid is purified by removing other metal ions and organic substances using the cation resin and anion resin. Can do.
[0011]
FIG. 1 is a view showing a waste liquid treatment apparatus according to an embodiment of the present invention. The treatment apparatus includes a storage tank 2 that stores a waste liquid 1 in which hexavalent chromium is dissolved, and a circulation line 3 for circulating the waste liquid 1. The circulation line 3 includes a formic acid injection unit 4, A hydrogen oxide injection section 5, a circulation pump 6, a heater 7, and an
[0012]
A method of reducing hexavalent chromium in the waste liquid 1 using the apparatus shown in FIG. 1 is performed as follows. When the pH of the waste liquid 1 is neutral to alkaline, hexavalent chromium (Cr 6+ ) exists as chromate ions (CrO 4 2− ) as shown in the following formula (1). Since this ion has a low redox potential, it has a weak oxidizing power.
CrO 4 2- + 4H 2 O + 3e - = Cr (OH) 3 + 5OH - E ° = - 0.13V ... (1)
[0013]
Therefore, usually an inorganic acid such as sulfuric acid is added as a pH adjuster to generate dichromate ions having strong oxidizing power as shown in formula (2), and a reducing agent is added to convert hexavalent chromium to trivalent chromium [ Cr 3+ ].
Cr 2 O 7 2- + 14H + + 6e - = 2Cr 3+ + 7H 2 OE ° = + 1.33V ... (2)
[0014]
The present invention is characterized in that formic acid that can be decomposed into carbon dioxide and water is used as a pH adjuster instead of the conventional inorganic acid. As an example, a case where potassium chromate [K 2 CrO 4 ] contained in a rust preventive paint for metal products is treated will be described. When formic acid [HCOOH] is added to the waste liquid 1 in which potassium chromate is dissolved, dichromic acid is generated as shown in the formula (3).
2K 2 CrO 4 + 4HCOOH = H 2 Cr 2 O 7 + 4KCOOH + H 2 O… (3)
[0015]
Next, when hydrogen peroxide [H 2 O 2 ] is added to the waste liquid 1 from the hydrogen peroxide injection part 5, hexavalent chromium of dichromic acid is reduced to trivalent chromium by the reaction shown in the formula (4).
H 2 Cr 2 O 7 + 6HCOOH + H 2 O 2 = 2Cr (COOH) 3 + 2O 2 + 5H 2 O… (4)
[0016]
Next, when the waste liquid 1 is passed through the cationic resin tower 9, trivalent chromium and potassium ions [K + ] are adsorbed to the cationic resin by the reactions (5) and (6). Is removed.
3R-SO 3 H + Cr (COOH) 3 = (R-SO 3 ) 3 Cr + 3HCOOH… (5)
R-SO 3 H + KCOOH = R-SO 3 K + HCOOH… (6)
[0017]
On the other hand, hydrogen peroxide acts as a reducing agent or an oxidizing agent depending on the redox potential of the partner as shown in the equations (7) and (8).
H 2 O 2 → O 2 + 2H + + 2e - E ° =-0.68V… (7)
H 2 O 2 + 2H + + 2e - → 2H 2 OE ° = 1.77V ... (8)
Therefore, hydrogen peroxide acts as an oxidizing agent for formic acid, and formic acid is decomposed into carbon dioxide [CO 2 ] and water by the reaction shown in the formula (9).
[0018]
HCOOH + H 2 O 2 = CO 2 + 2H 2 O… (9)
[0019]
If water is passed through the cation resin tower 9 with hydrogen peroxide remaining in the waste liquid 1, the resin deteriorates due to the oxidizing power of hydrogen peroxide, and the exchange capacity decreases. In order to prevent deterioration of the resin, the waste liquid 1 circulated from the
[0020]
As described above, formic acid and hydrogen peroxide added to the reduction treatment of hexavalent chromium are decomposed into carbon dioxide gas, oxygen gas and water, so that the amount of secondary waste accompanying the reduction treatment can be greatly reduced.
[0021]
Next, in order to confirm the reactions (4) to (6) and (9), the results of measuring chromium, potassium and organic carbon (TOC) before and after the treatment of the waste liquid 1 are shown in FIG. In the waste liquid 1 before the treatment, 78 ppm of chromium and 110 ppm of potassium were dissolved. 2000 ppm formic acid was added to this waste liquid, hexavalent chromium was reduced to trivalent chromium with hydrogen peroxide, and trivalent chromium and potassium ions were removed with a cationic resin. As a result, chromium ions and potassium ions in the waste liquid 1 were reduced to 0.5 ppm or less, which is below the detection limit value. Further, the concentration of organic carbon (TOC) indicating the presence of formic acid was about 520 ppm before the test, but it was reduced to 1 ppm or less, which is below the detection limit value, by decomposition into carbon dioxide gas and water with hydrogen peroxide.
Since the decomposition rate of formic acid is higher as the temperature is higher, the temperature of the waste liquid 1 is raised to 50 ° C. or higher by the heater 7 when formic acid is decomposed in a short time.
[0022]
After completion of formic acid decomposition, the waste liquid 1 is passed through the cation resin tower 9 and the anion resin tower 10 to remove other metal ions and organic substances. When discharging the purified waste liquid, discharge it after confirming that it is below the wastewater standard value.
[0023]
Next, the result of trial calculation of the amount of secondary waste generated by the reduction treatment of hexavalent chromium according to the present invention and the conventional method will be described. The trial calculation conditions for the amount of secondary waste generated are potassium dichromate, 200 ppm chromium, and 100 m 3 waste liquid. The treatment method was carried out in the procedure of pH adjustment → reduction treatment → neutralization treatment in both the present invention and the conventional method.
[0024]
The conventional method will be described in the case of reduction treatment with sodium bisulfite. Sulfuric acid [H 2 SO 4 ] is added to the waste liquid in which potassium chromate is dissolved to generate dichromic acid as shown in the formula (10).
2K 2 CrO 4 + 2H 2 SO 4 = H 2 Cr 2 O 7 + 2K 2 SO 4 + H 2 O… (10)
[0025]
Sodium bisulfite [NaHSO 3 ] is added to reduce hexavalent chromium to trivalent chromium as shown in formula (11).
2H 2 Cr 2 O 7 + 6NaHSO 3 + 3H 2 SO 4 = 2Cr 2 (SO 4 ) 3 + 3 Na 2 SO 4 + 8H 2 O… (11)
[0026]
Add sodium hydroxide [NaOH] (12) to produce chromium hydroxide [Cr (OH) 3 ], potassium hydroxide [KOH] and sodium sulfate [Na 2 SO 4 ] as shown in formula (13) To do.
Cr 2 (SO 4 ) 3 + 6NaOH = 2 Cr (OH) 3 + 3 Na 2 SO 4 … (12)
K 2 SO 4 + 2NaOH = 2 KOH + Na 2 SO 4 … (13)
[0027]
Therefore, in the conventional method, chromium hydroxide, potassium hydroxide and sodium sulfate indicated by the underline of the equations (11) to (13) are secondary waste.
On the other hand, in the reduction treatment of the present invention, the pH is adjusted with formic acid as shown in formula (4). Thereafter, hydrogen peroxide is added to decompose formic acid as shown in equations (14) and (15).
Cr (COOH) 3 + 3H 2 O 2 = Cr (OH) 3 + 3CO 2 + 3H 2 O… (14)
KCOOH + H 2 O 2 = KOH + CO 2 + H 2 O… (15)
[0028]
Therefore, the secondary waste generated in the present invention is only chromium hydroxide and potassium hydroxide.
FIG. 3 shows the result of trial calculation of the secondary waste of the present invention and the conventional method. As is apparent from the figure, in the present invention, only the amount of waste resulting from potassium chromate is used, but in the conventional method, sodium sulfate generated after neutralization is added. Therefore, the waste generation amount of the present invention is about 1/3 of the conventional method.
[0029]
As described above, in the present invention, formic acid that can be decomposed into carbon dioxide and water is used as the pH adjuster of the waste liquid, so that the amount of waste generated can be greatly reduced.
In the conventional method, neutralization is performed after reduction, but the precipitate generated by the neutralization is separated from the supernatant, and the precipitate is recovered and disposed of. In order to treat a large amount of waste liquid, a large-scale apparatus is required, and operations such as pH adjustment and handling of precipitates are complicated.
[0030]
On the other hand, in the present invention, since the waste liquid after the reduction treatment and after the decomposition of formic acid is purified with an ion exchange resin, the configuration of the apparatus is very simple, and the handling environment is greatly improved since there is no handling of precipitates.
[0031]
【The invention's effect】
According to the present invention, it is possible to provide a waste liquid treatment method and apparatus that generate a small amount of secondary waste and that have a good work environment.
[Brief description of the drawings]
FIG. 1 is a system diagram of a waste liquid treatment apparatus according to an embodiment of the present invention.
FIG. 2 is a bar graph illustrating the effect of the present invention, showing the results of removing chromium and potassium from waste liquid with a cationic resin and the results of decomposing organic carbon of formic acid with hydrogen peroxide.
FIG. 3 is a bar graph showing the result of trial calculation of the amount of secondary waste generated by the method of the present invention and the conventional method, and explaining the effect of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Waste liquid, 2 ... Storage tank, 3 ... Circulation line, 4 ... Formic acid injection | pouring part, 5 ... Hydrogen peroxide injection | pouring part, 6 ... Circulation pump, 7 ... Heater, 8 ... Ultraviolet irradiation part, 9 ... Cationic resin tower, 10 ... anion resin tower, 11 ... exhaust line.
Claims (5)
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| JPWO2015075798A1 (en) * | 2013-11-21 | 2017-03-16 | 株式会社日立製作所 | Element separation method and separation system |
| JP6393158B2 (en) * | 2014-11-11 | 2018-09-19 | 日立Ｇｅニュークリア・エナジー株式会社 | Secondary waste reduction method for chemical decontamination, secondary waste elution recovery device, and chemical decontamination system |
| CN105118540B (en) * | 2015-08-20 | 2018-01-12 | 中电投远达环保工程有限公司 | Radioactive myocardial damage handling process |
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