EP0555996B1 - Methods and apparatus for treating aqueous indutrial effluent - Google Patents

Methods and apparatus for treating aqueous indutrial effluent Download PDF

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Publication number
EP0555996B1
EP0555996B1 EP93300841A EP93300841A EP0555996B1 EP 0555996 B1 EP0555996 B1 EP 0555996B1 EP 93300841 A EP93300841 A EP 93300841A EP 93300841 A EP93300841 A EP 93300841A EP 0555996 B1 EP0555996 B1 EP 0555996B1
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EP
European Patent Office
Prior art keywords
effluent
gas
species
vessel
separation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93300841A
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German (de)
English (en)
French (fr)
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EP0555996A3 (en
EP0555996A2 (en
Inventor
Tetsuo Fukasawa
Koichi Chino
Masami Matsuda
Tsutomu Baba
Akira Sasahira
Tomotaka Nakamura
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Hitachi Ltd
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Hitachi Ltd
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Publication of EP0555996A3 publication Critical patent/EP0555996A3/en
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G21F9/10—Processing by flocculation
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing

Definitions

  • This invention relates to methods and apparatus for treating aqueous industrial effluent.
  • it relates to the treatment of radioactive effluent e.g. from nuclear power stations, spent fuel reprocessing plants, radioisotope handling facilities and other nuclear-related facilities.
  • radioactive effluent e.g. from nuclear power stations, spent fuel reprocessing plants, radioisotope handling facilities and other nuclear-related facilities.
  • it may also relate to other types of industrial effluent from which it is desired to separate dissolved components.
  • a typical radioactive effluent contains a variety of radionuclides in aqueous solution, in volumes too large for long-term management. It is conventional to treat this effluent solution to separate out the radionuclides - typically a mixture of heavy transition metal ions - into a more concentrated form, typically by precipitation, coprecipitation, ion exchange, adsorption or solvent extraction.
  • radionuclides such as iodine in reprocessing effluent
  • iodine in reprocessing effluent are volatile and tend to be released gradually from the effluent throughout the separation process. Special measures are needed to contain and adsorb these volatile radioactive substances.
  • Separation processes of the type described also have relevance to other types of industrial effluent containing useful or hazardous components which it is desired to recover or remove. Examples arise in noble metal refining industry, metal plating industry and catalyst manufacture.
  • the invention provides a method of treating aqueous industrial effluent, in which a first, cationic transition metal species dissolved in the effluent is separated from the effluent by a separation treatment, selected from
  • second species include oxy-anions of carbon, nitrogen and sulphur, and organic ligands.
  • the second species undergoes chemical conversion to form the gas.
  • carbonates may be converted to carbon dioxide, nitrates to volatile nitrogen oxides, and iodide oxidised or iodate reduced to volatile iodine.
  • the preliminary step may comprise one or more of oxidising or reducing the second species, adjusting the pH of the effluent, heating and/or agitating the effluent, and bubbling some other gas through the effluent, to achieve the desired gas release.
  • the invention provides in a particular aspect a method of treating aqueous radioactive effluent in which at least one dissolved radionuclide (cationic transition metal) is separated from the effluent by a separation treatment of the kind described characterised by a preliminary step of treating the effluent before the separation treatment in the manner described above.
  • a separation treatment of the kind described characterised by a preliminary step of treating the effluent before the separation treatment in the manner described above.
  • the gas released from the effluent may itself be radioactive.
  • the released gas should be contained, and desirably absorbed or adsorbed, to prevent its spread in the system.
  • apparatus for treating aqueous radioactive effluent comprising an enclosed vessel to receive and hold the effluent, and separation means for separating dissolved radionuclides from the effluent by a separation method selected from precipitation, co-precipitation, ion exchange, absorption and solvent extraction, characterised by
  • a typical radioactive effluent contains, for example, sodium ion, nitrate, sulphate and carbonate at roughly molar levels (non-radioactive species) and radioactive species such as Cs + , Sr + , Am 3+ , NpO 2 2+ , TcO 4 - , I - and CO 3 2 - at the order of hundredth-molar concentrations.
  • radioactive species such as Cs + , Sr + , Am 3+ , NpO 2 2+ , TcO 4 - , I - and CO 3 2 - at the order of hundredth-molar concentrations.
  • Carbonate may have-come from the reprocessing process, also as an impurity in NaOH.
  • Carbon may also be present in organics such as carboxylates e.g. citrate and EDTA used in apparatus
  • Fig. 3 illustrates a method and apparatus for removing carbonate and iodine from reprocessor spent fuel effluent, using an initial pH adjustment step followed by conventional coprecipitation of radionuclides.
  • Reprocessed effluent 1 containing radionuclides such as 137 Cs, 90 Sr, 14 C, 237 Np and 241 Am is contained in a batch in an effluent processing tank 2, from previous processing indicated schematically at 3. Typical treatment volumes vary between 0.001 and 1 m 3 /day, so a batch process may need to be carried out only once a day or less.
  • a pM adjuster was introduced controllably from pM adjuster supply tank 4 into the effluent, to adjust its pH. Where the effluent pH is high, an acid such as nitric acid is a suitable adjuster. The pH is reduced to a suitably low value e.g. from 2 to 4.
  • Evolved gas containing partly radioactive CO 2 and I 2 , was collected in an adjacent gas processor 6 to prevent scattering of its radioactivity into the surroundings.
  • a suitable gas processor 6 contains a silver-based adsorbent e.g. silver alumina, to remove the iodine, and some suitable absorbent for CO 2 , preferably a solid such as CaCO 3 or BaCO 3 to minimise volume.
  • a valve 6 is closed to isolate the gas processor 6 from the effluent tank 2.
  • Coprecipitating agent is then fed into the tank 2 from coprecipitating agent supply tank 5, to coprecipitate radionuclides.
  • conventional reagents such as sodium phosphomolybdate and ferrocyanic acid (for Cs), calcium phosphate and barium sulphate (for Sr) and ferric hydroxide and oxalate (for Np and Am) are used.
  • the various reagents need not necessarily be added simultaneously, but it is desirable to add them in one stage to simplify the processing, provided that the conditions required for the respective coprecipitations do not differ greatly. Since the effluent is substantially carbonate-free, coprecipitation occurs with high efficiency. Again the agitator 8 is operated, to promote formation of precipitate with entrainment of radionuclide.
  • the effluent processing tank 2, the supply tanks 4,5 and gas processor 6 form an integrated enclosed structure, preventing escape of volatile components into the surroundings.
  • a filter e.g. a sintered metal filter or tubular filament, is an effective separator for the precipitate. Filtered effluent gradually enters the processed effluent receiving tank 11. The precipitate, rich in radionuclides, remains on the filter to be collected for long-term management.
  • the filter is backwashed by a cleaning fluid, from cleaning fluid storage tank 12 by backwash pump 13, into a precipitate receiving tank 14. Water may be used for backwash. The smallest possible volume is used, to minimise the volume of the high-activity effluent portion.
  • the reprocessing effluent is processed into two parts: the liquid with very substantially reduced radioactivity level, and the precipitate containing most of the activity from the original effluent.
  • the volume of the processed liquid effluent is scarcely less than the original effluent volume, but its radionuclide concentration is reduced typically to below 1% of the original value.
  • the concentration of radionuclide in the precipitate is more than a hundred times the concentration in the original effluent, with a volume about one hundredth the original effluent volume.
  • the preliminary removal of carbon dioxide enhances the decontamination of Am and other transition elements showing a decontamination characteristic corresponding to that of Fig. 1.
  • the concomitant removal of radioactive iodine deals with this iodine at an early stage and prevents it from volatilising and scattering to interfere with the subsequent filtering etc. processes. Consequently special iodine adsorbers are not needed at these subsequent stages.
  • the pretreatment and the precipitation can be carried out in a single vessel, so simple plant can be used.
  • the degassing can be promoted further by heating the effluent, and/or blowing gas (e.g. air) through it in addition to adjusting the pH.
  • blowing gas e.g. air
  • Fig. 4 shows an embodiment in which effluent from a nuclear power plant is treated.
  • the effluent 15, containing radionuclides such as 137 Cs, 90 Sr, 14 C, 129 I and 60 Co, is fed from the effluent supply tank 17 of the nuclear power plant to an effluent processing tank 16.
  • a perforated conduit 19 extends into the tank, for bubbling gas through the tank contents from a gas supply container 18.
  • a heater 33 is also provided for heating the tank.
  • the effluent is treated by bubbling gas through it to promote the volatilisation of certain components therein, such as 12 C/ 14 C and I/ 129 I which volatilise as carbon dioxide and iodine respectively.
  • an acid gas such as NO x is appropriate for bubbling from the supply 18. It reduces the pH of the effluent, with a result as described previously. If the pH is not high, air can be used. The effect is slower, but the bubbling of air (lean in CO 2 ) through the richly carbonated effluent gradually reduces the carbonate by taking out carbon dioxide. The same can occur with other dissolved volatile components.
  • Suitable shaping of the gas conduit 19, as well as heating of the effluent, can further promote escape of volatiles.
  • the released gases containing radioactive iodine and CO 2 in this case, are collected into gas processor 20 and adsorbed/absorbed as in the first embodiment, without scattering into the environment.
  • the valve 20 is then closed to isolate the effluent from the gas processor and inhibit any tendency for redissolving.
  • the effluent then passes to an ion exchange column 21, for separation of the metal species.
  • Conventional ion exchangers such as ammonium phosphomolybdate, cobalt potassium ferrocyanate and copper-impregnated zeolite ferrocyanate (for Cs), and sodium titanate and titanium phosphate (for Sr and Co) may be used.
  • the ion exchange processes need not all be applied concurrently, but if conditions allow it is nevertheless preferred that they be all loaded into one column.
  • Aqueous effluent lean in radionuclides passes from the ion exchange column 21 to the processed effluent storage tank 23.
  • the ion exchanger operates until it starts to be exhausted, whereupon it is removed and replaced (using flanges 22). Replacement due time is assessed, in a known manner, by measuring radionuclide concentration in the liquid leaching from the column.
  • the exhausted ion exchanger is handled as relatively high-level waste or, if it is of a reusable type, it is regenerated for re-use and the regenerative solution (containing highly concentrated radionuclide at small volume) is the high-level waste.
  • the original effluent separates into two portions, a small-volume high-activity ion exchanger portion and a large-volume low-activity processed liquid effluent.
  • the ion exchanger portion volume is typically less than one fiftieth of the original effluent volume.
  • effluents typically include useful or hazardous components which it is desired to recover/remove.
  • Typical of such elements are Ru, Pd, Pt, Au, Cr and Cd.
  • the apparatus is broadly similar to that in the first embodiment.
  • Industrial effluent 24 containing components as mentioned is supplied from the effluent supply tank 26 into the effluent processing tank 25 for treatment. Taking account of the specific nature of the effluent, it is treated with oxidising or reducing agent from oxidising/reducing agent supply container 27.
  • Ce (oxidising) and Ru, Pd (reducing) may be relevant.
  • dissolved nitrates which may stabilise dissolved platinum group species
  • carbonate can be removed as carbon dioxide by using acidic agents.
  • an agitator 38 promotes the reactions and the evolution of the volatile products. Volatiles such as NO x and CO 2 are discharged through gas outlet 29. According to the nature of the volatiles, it may not be necessary to isolate them from the surroundings. It is however desirable to close the gas outlet 29 by valve 29 to prevent re-dissolving of the removed substances when gas evolution has substantially finished.
  • Suitable ion exchange substances for the useful/hazardous components are fed into the processing tank 25 from an ion exchanger supply 28.
  • Ion exchanger substances such as described in the second embodiment may be relevant. If plural they need not all be added simultaneously, but simultaneous addition is preferable.
  • the ion exchanger with the adsorbed components is then sent by slurry transfer pump 39 to separating mechanism 30, e.g. a filter (sintered metal or tubular filament) to separate the ion exchange material from the liquid effluent.
  • separating mechanism 30 e.g. a filter (sintered metal or tubular filament) to separate the ion exchange material from the liquid effluent.
  • Liquid effluent, separated from the ion exchanger and substantially free of the desired/dangerous component passes gradually to the processed effluent tank 41.
  • the ion exchange material incorporating the desired/dangerous component(s) is transferred from the separating mechanism e.g. by backwash or mechanical removal, to the ion exchanger receiving tank 32.
  • Backwash e.g. by water, may be from cleaning liquid tank 31 through transfer pump 43.
  • the liquid effluent may be rendered into a state in which it can safely be discharged into the environment e.g. the sea or a river.
  • the useful or dangerous substances are concentrated into a low volume making it more efficient to recover or dispose of the materials as appropriate.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Treatment Of Water By Ion Exchange (AREA)
  • Physical Water Treatments (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Water Treatment By Sorption (AREA)
  • Treating Waste Gases (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
EP93300841A 1992-02-10 1993-02-04 Methods and apparatus for treating aqueous indutrial effluent Expired - Lifetime EP0555996B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2373392 1992-02-10
JP4023733A JP2738478B2 (ja) 1992-02-10 1992-02-10 放射性廃液中の放射性核種の分離方法および産業廃液中の有用または有害元素の分離方法
JP23733/92 1992-02-10

Publications (3)

Publication Number Publication Date
EP0555996A2 EP0555996A2 (en) 1993-08-18
EP0555996A3 EP0555996A3 (en) 1993-12-15
EP0555996B1 true EP0555996B1 (en) 1999-11-24

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Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2714620B1 (fr) * 1993-12-31 1996-02-23 Gagneraud Pere Fils Entr Procédé et installation d'épuration de composés chimiques ou nucléaires d'un effluent.
FR2861494B1 (fr) * 2003-10-28 2005-12-23 Commissariat Energie Atomique Utilisation de carbonates mixtes frittes pour le confinement de carbone radioactif.
EP1780730A1 (en) * 2005-11-01 2007-05-02 Paul Scherrer Institut Fast reduction of iodine species to iodide
FR2927725B1 (fr) * 2008-02-18 2014-09-05 Commissariat Energie Atomique Procede de decontamination d'un effluent liquide en un ou plusieurs elements chimiques par extraction solide-liquide mettant en oeuvre une boucle de recyclage
FR2937634B1 (fr) * 2008-10-27 2011-09-30 Commissariat Energie Atomique Procede de decontamination d'un effluent liquide comprenant un ou plusieurs elements chimiques radioactifs par traitement en lit fluidise
JP5866823B2 (ja) * 2011-06-29 2016-02-24 三菱レイヨン株式会社 廃水の処理方法および処理装置
JP6532077B2 (ja) * 2014-04-18 2019-06-19 一般財団法人電力中央研究所 放射性ストロンチウムの分離方法及び分離システム
JP6585405B2 (ja) * 2015-07-17 2019-10-02 株式会社神戸製鋼所 放射性汚染水貯留方法及び放射性汚染水貯留装置
CN110759550A (zh) * 2019-12-05 2020-02-07 徐州市天益塑料制品有限公司 一种污水处理装置
CN112509721A (zh) * 2020-11-30 2021-03-16 湖南汉华京电清洁能源科技有限公司 放射性样品处理方法及装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2655469A1 (fr) * 1989-12-06 1991-06-07 Wiederaufarbeitung Von Kernbre Procede et installation pour diminuer la teneur en iode d'une solution nitrique de matieres combustibles nucleaires.

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Publication number Priority date Publication date Assignee Title
DE2951339C2 (de) * 1979-12-20 1985-11-21 Kernforschungszentrum Karlsruhe Gmbh, 7500 Karlsruhe Verfahren zum Desorbieren von Spaltjod aus salpetersaurer Brennstofflösung
JPS6152753A (ja) * 1984-08-22 1986-03-15 Nec Corp 障害処理装置
JPH0644074B2 (ja) * 1986-02-18 1994-06-08 動力炉・核燃料開発事業団 ウランおよびフツ素含有廃水の処理方法
JPS6453199A (en) * 1987-08-24 1989-03-01 Nippon Atomic Ind Group Co Method for removing radioactive iodine in waste organic solvent
FR2641119A1 (en) * 1988-12-28 1990-06-29 Commissariat Energie Atomique Process for complementary desorption of the radioactive iodine present in the nitric solution for dissolving irradiated fuel elements

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2655469A1 (fr) * 1989-12-06 1991-06-07 Wiederaufarbeitung Von Kernbre Procede et installation pour diminuer la teneur en iode d'une solution nitrique de matieres combustibles nucleaires.

Also Published As

Publication number Publication date
EP0555996A3 (en) 1993-12-15
JPH05220467A (ja) 1993-08-31
JP2738478B2 (ja) 1998-04-08
EP0555996A2 (en) 1993-08-18

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