Classifications

• • 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
  • G21F9/18—Processing by biological processes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S210/00—Liquid purification or separation
  • Y10S210/902—Materials removed
  • Y10S210/911—Cumulative poison
  • Y10S210/912—Heavy metal

Definitions

• the invention relates to a method and a device for treating oils and solvents contaminated with radioactive substances.
• these microorganisms act in the presence of a very large quantity of water and in the presence of oxygen, the ratio between the respective volumes of water and oil being approximately 100/5 or 20/1.
• oils and solvents contaminated by radioactive substances are subject to increasingly stringent regulations which prohibit contamination of the atmosphere or of wastewater drainage systems, so as not to disperse the radioactive substances contained in these oils and solvents.
• Nuclear power plants, in France and in other countries, have increasing volumes of contaminated oils and solvents in stock, which must be stored until a solution is found in accordance with the regulations in force to treat them.
• the aim of the present invention is to remedy the drawbacks of known methods and devices, and to propose a method and a device for treating oils and solvents contaminated by radioactive substances, this method and this device being adapted to allow discharge into the atmosphere or collection networks, air and water, the characteristics of which comply with the requirements of the regulations in force, the radioactive substances being collected in a very small volume of waste which it is easy to process and store for avoid contamination of the environment.
• the process targeted by the invention for treating oils and solvents contaminated by radioactive substances comprises the step which consists in subjecting these oils and solvents to the action of micro-organisms preselected in the presence air and a very large volume of water compared to the volume of oils and solvents to be treated, these microorganisms being adapted to destroy organic molecules to transform them in particular into CO 2 and H 2 O.
• this method is characterized in that it further comprises the following steps: a) a predetermined volume of water is prepared having predetermined characteristics in terms of dissolved oxygen content, pH and REDOX potential; b) a predetermined charge of oils and solvents contaminated with radioactive substances is added to this volume of water, said charge corresponding to a volume of oils and solvents which is a predetermined fraction of the predetermined volume of water; c) this charge is subjected to the action of microorganisms at a temperature and for a predetermined duration; d) at least part of the effluent obtained is removed; e) the water is separated from the materials contained in this effluent; f) said separated materials are recycled or removed from this water; g) regenerating this water, freed from the materials contained in the effluent, so as to restore it to said predetermined characteristics; h) at least part of this water is recycled; i) the cycle is restarted from step a).
• the merit of the present inventor is that he was able, on a pilot scale, to cope with the increase in the content of treatment residues, due to the recycling of the effluents collected, so as to find himself permanently in conditions close to the initial conditions under which it is known that microorganisms are capable of degrading and breaking down oils and solvents. It is thus possible to transform the organic molecules substantially completely into CO 2 and H 2 O.
• the radioactive substances and the other materials contained in the collected effluent are separated from the water in step e) and recycled or treated in step f) so as to only constitute a small volume of residues much easier to process and store than the initial volume of contaminated oils and solvents.
• a predetermined volume of regenerated water is discharged corresponding substantially to the volume of a new charge of oils and solvents contaminated with radioactive substances. This allows you to check that the operation is working properly.
• the volume of liquid discharges from the implementation of the process according to the present invention is thus substantially equal to the volume of degraded oils and solvents, regardless of the fact that these liquid discharges completely comply with the requirements of the regulations in force.
• preselected mineral supports of microorganisms are used to fix at least part of the metals present in the charge by ion exchange.
• the effluent is clarified by decantation, and the sludge thus obtained is recycled to step c).
• evaporation of the effluent water is carried out under vacuum and for step g) the water collected after evaporation and condensation is used, while recovering the residues from this vacuum evaporation operation and subjecting them to drying in a fluidized bed.
• the device for implementing the method of the invention is characterized in that it comprises:
• FIG. 1 is a block diagram of an embodiment of the device according to the present invention.
• FIG. 2 is a perspective view with cutaway, of the device shown schematically in Figure 1;
• - Figure 3 is a view similar to Figure 1 of another embodiment of the device of the invention;
• FIG. 4 is a schematic elevational view of an apparatus for reactivating and developing microorganisms
• - Figure 5 is a schematic sectional view of a hydro-ejector
• - Figure 6 is a schematic sectional view of a fluidized bed dryer.
• a premixer 2 adapted to receive a predetermined volume of water and a predetermined charge of contaminated oils and solvents, as well as micro ⁇ organisms which will be specified below;
• a first reactor 3 adapted to receive at least part of the mixture coming from the premixer 2, the microorganisms and the mineral supports shown diagrammatically in 4, which will be specified below;
• a second reactor 5 adapted to receive the mixture leaving the first reactor 3, and microorganisms;
• a clarifier 7 for separating the water from the materials contained in the mixture leaving the second reactor 5;
• the device according to the invention also comprises means, by gravity or by pumping, shown diagrammatically at 10, for transferring into the first reactor
• SUBSTITUTE SHEET shown schematically in 13 to introduce into a buffer tank 16 the water supernatant in the clarifier 7, similar means 14 to recycle in the premixer 2 the sludge which accumulates at the bottom of the clarifier 7, similar means shown schematically in 15 to send to the evaporator 8 the water stored in the buffer tank 16, as well as similar means shown diagrammatically at 17, for recycling to the premixer 2 and possibly to an external network shown diagrammatically at 18, the evaporated and condensed water collected in a tank 19 in which it is regenerated.
• the means 6 for injecting air comprise a network, shown diagrammatically at 20, of compressed air distribution and ramps shown diagrammatically at 21, for injecting compressed air at the lower part of the premixer 2 , of the first reactor 3 and of the second reactor 5.
• This injection of air constitutes an oxygen supply in the bath of each container and at the same time ensures mixing of said bath.
• the first reactor 3 is equipped with a mixing device which includes a pump 22 which sends the reaction medium of the reactor 3 in a mixing tank 22a whose overflow, shown diagrammatically at 23, falls back into the reactor 3 .
• the clarifier 7 is a clarifier of any known type which need not be described in detail here.
• the clarification is carried out by decantation, the mixture coming from the second reactor 5 entering the clarifier 7 through an axial tubular column 24 and coming into contact, if necessary, with flocculating agents which are introduced in any manner not shown .
• the residues collected at the bottom of the evaporator 8 are sent to a processing unit 25 in which they are, for example, dried and conditioned for storage, since these residues include radioactive substances. If necessary, the sludge collected at the bottom of the clarifier 7 can also be sent to the treatment unit 25.
• the reservoir 19 for collecting and regenerating condensed water is equipped with means known in themselves for regenerating this water.
• the processing device is, in a preferred embodiment, installed on a platform 26 likely to be transported on the platform of a truck or trailer.
• This platform has a peripheral side wall 27.
• the assembly formed by the platform 26 and the wall 27 constitutes a retention tank 28 which prevents the discharge to the outside of any radioactive fluid in the event of an incident.
• the retention tank 28 is itself covered with a substantially sealed cabin 29 maintained slightly under vacuum by a ventilation and air filtering system 30, of any known type which it is unnecessary to describe here.
• FIG. 1 also shows diagrammatically an inlet 31 for the load of oils and solvents contaminated by radioactive substances, as well as an inlet 32 for microorganisms in the broad sense, that is to say from the mixture of micro ⁇ organisms proper, with the usual nutrients, activators and other supplements, trace elements and others, which are known in themselves.
• the method implemented in the device 1 according to the invention for treating oils and solvents contaminated with radioactive substances, comprises the conventional step which consists in subjecting these oils and solvents to the action of micro-organisms preselected in the presence air and a very large volume of water compared to the volume of oils and solvents to be treated, these microorganisms being adapted to destroy organic molecules to transform them in particular into CO 2 and H 2 O.
• this process is characterized in that it further comprises the following steps: a) a predetermined volume of water is prepared having predetermined characteristics in terms of dissolved oxygen content, pH and REDOX potential; b) a predetermined charge of oils and solvents contaminated with radioactive substances is added to this volume of water, said charge corresponding to a volume of oils and solvents which is a predetermined fraction of the predetermined volume of water; c) this charge is subjected to the action of microorganisms at a temperature and for a predetermined duration; d) at least part of the effluent obtained is removed; e) the water is separated from the materials contained in this effluent; f) said separated materials are recycled or removed from this water; g) regenerating this water, freed from the materials contained in the effluent, so as to restore it to said predetermined characteristics; h) part of this regenerated water is recycled; i) the cycle is restarted from step a); j) evacuating a volume of water
• This process was developed to treat oils and solvents contaminated by radio-elements and produced by the mechanical maintenance activities of equipment located in controlled areas of nuclear power plants and other nuclear installations and reactors.
• oils and solvents which are stored in containers, are radioactive and contaminated in particular by the following long-lived radio-elements: cobalt 58, 60 and 62, manganese 54, silver 110, cesium 134 and 137, zinc 65, niobium 95 , antimony 124 and 125.
• the average activity rate of contaminated products is around 700 Becquerels per liter, with varying rates depending on the container, from 50 to 9,000 Becquerels per liter.
• Oils and solvents are composed, at more than 98%, of an apolar fraction essentially containing saturated hydrocarbons C n H ⁇ + 2 , with a predominance of alkanes nC 2 o and nC 2 ⁇ which correspond to branched aliphatic hydrocarbons .
• the oxidation of arachidic acid and n-alkanes, catalyzed by microorganisms present in the reactor, can result in gelation of the bath.
• the merit of the present inventor has been to solve this gelation problem, the formation of which from metabolites may be faster than the degradation of these same metabolites, by developing a method making it possible to avoid this gelation.
• the most important and representative mechanism is the degradation of alkanes by oxidation of the methyl terminal group.
• the carbon of the terminal methyl group -CH 3 is oxidized to primary alcohol -CH 2 OH, then to aldehyde-CHO then to primary acid -CH 2 OH. This acid is then metabolized by ⁇ -oxidation directly or via the formation of diacid ( ⁇ -hydroxylation).
• oxidation of the methyl group is considered to be the main metabolic pathway.
• the methyl group oxidation mechanism is no different from the oxidation mechanism of n-alkanes.
• polyethylene glycol gives compounds which, depending on the number of monomers, can be liquid or solid and the mixture of which can give a viscous product close to gelation. The presence of such a gel would prevent any further development and any action of the microorganisms, since the oxygen could no longer dissolve in the reaction bath.
• the free water produced represents approximately 80% of the weight of the oils and solvents treated if one does not take into account the natural evaporation and the addition of water necessary for sowing and for life. microorganisms (development and reproduction).
• the temperature, 30 to 35 ° C, and the pH, from 6.5 to 7.5, have the recommended values for the development and action of microorganisms.
• microorganisms are chosen from the industrial microorganisms available on the market. They are for example chosen from the "BIO ACTIV 200" range from the company TBA (APPLIED TECHNIQUES AND BIOCHEMISTRY). These microorganisms can be conventionally fixed on mineral supports and are conventionally used with suitable nutrients, as well as with emulsifying agents.
• microorganisms used are therefore mixtures of known strains which are substantially specialized in attacking specific products. These mixtures are conventionally prepared so as to be effective in decomposing the main constituents of the oils and solvents to be degraded, but also the abovementioned intermediate by-products of decomposition of these constituents.
• the mixture of micro ⁇ organisms will include the strains having the following codes:
• - 201 suitable for the treatment of light halogenated and non-halogenated aliphatic hydrocarbons
• - 202 suitable for the treatment of simple non-halogenated aromatic compounds
• - 206 suitable for the treatment of polychlorobiphenyls and chlorobenzoates
• - 208 suitable for the treatment of non-halogenated hydrocarbons and petroleum derivatives.
• any other strain adapted to a specific product or by-product will be added, as well as the nutritive compounds and trace elements as well as, if necessary, the mineral supports, necessary for the development and the action of these microorganisms.
• the nutritional balance of the bath must be constantly maintained in the CARBON / NITROGEN / PHOSPHORUS ratio little different from 100/5/1.
• the contents of the reaction bath in microorganisms and nutrients are those usual for these materials.
• Pre-selected mineral supports are preferably used on which the microorganisms are fixed and which will fix the radioactive heavy metals present in the charge by ion exchange.
• the mineral supports conventionally comprise the following components:
• alumina silicate in particular potassium alumina silicate
• the mixture coming from the second reactor 5 is clarified by decantation, adding, if necessary, a flocculant which does not hinder the smooth running of the process, and the sludges thus obtained are recycled to the step c).
• Evaporating the water from the effluent leaving the clarification is carried out under vacuum and for step g) the water collected after evaporation and condensation is used.
• step g) the water, freed of the materials contained in the effluent, is regenerated so as to restore it to the initial characteristics, for example the following characteristics:
• - REDOX potential greater than -150 mv and preferably positive (up to 70 mv).
• This regeneration can be done for example by adding hydrogen peroxide and sodium hydroxide.
• waste includes the two aforementioned by-products as well as polyethylene glycol.
• the proportion of this waste is around 3 per thousand by weight: this means that there will be approximately 3 kg of ultimate waste for approximately 1000 kg of degraded oils or solvents.
• the above process can be carried out continuously or discontinuously. It makes it possible to permanently treat the effluent which represents approximately 20 times the volume of oils to be degraded, and to return water to the premixer having the same characteristics as the starting water supplied by a public water distribution network. , that is to say :
• the device according to the invention which is in the form of an installation mounted on at least one platform transportable by road, can be easily moved from one site to another to treat in each site contaminated oils and solvents and decompose them essentially into CO 2 and H 2 O, with a very low quantity of releases containing radioactive substances, of the order of 3 per thousand by weight of the oils and solvents treated.
• This device also has the advantage of eliminating any transport of radioactive oils and solvents to a site for processing these oils and solvents.
• the mixture resulting from the biodegradation in the reactor 3 is transferred by the pump 37 to a primary decanter 41 at a flow rate much greater than the nominal flow rate of the installation.
• the biomass recovered from the bottom of the primary settling tank 41 is returned to the premixer 2 by the pump 14.
• the mixture thus freed from most of the suspended matter and the incompletely degraded fat is transferred to the reactor 5 by means of the pump 11.
• the COD at this time is of the order of 40,000 ppm.
• the mixture thus transferred to reactor 5 is again subjected to the action of new microorganisms which destroy fatty acids. This causes the COD to drop to a rate close to 300 ppm.
• the mixture treated in reactor 5 is sent by means of the pump
• Clarified water which contains some miscible products, by-products of biodegradation such as Diethylene glycol dibutyl ether, Polyethylene glycol Methyl Ether and Ditrertiobuthyl-4-methyl phenol plus residues of carbon chains (n-C 2 to C 2 alkanes) ⁇ ), is sent to the vacuum evaporator 8.
• the demineralized water produced by the condenser 9 of the evaporator 8 is sent to the container 19 where it is regenerated by means of the system 40 in REDOX potential with hydrogen peroxide, in pH with soda and aerated by forced recirculation through a microporous sprayer.
• This thus reconstituted water having the characteristics of industrial water is returned to the premixer 2 where it participates in a new degradation cycle.
• Such treatment is known in itself.
• the condenser 9 is associated with a conventional refrigeration unit 9a.
• the ultimate waste recovered at the foot of the evaporator 8 is sent to a buffer tank 24 whose volume corresponds to three days of operation of the installation.
• the product is homogenized by adding water and air, then it is sent under pressure through an atomizer to the drying member 25 in a fluidized bed.
• a quantity of regenerated water in the container 19 corresponding to the quantity of degraded oil is withdrawn during its transfer from the container 19 to the premixer 2.
• This water is stored in the container 39 from where it is taken up by the pump. 35 to be passed through an activated carbon filter 36 for refining. It is this water, the characteristics of which comply with the legislation in force, which is returned at the end of the operation to be released into the environment in 39a.
• the activated carbon filter practically removes the last organic matter (COD) contained in this regenerated condensed water.
• a reservoir 60 is used to reactivate and develop the microorganisms and the nutritive products which are supplied by three metering devices 61a, 61b, 61c.
• Three feeders 62a, 62b, 62c with adjustable flow are intended to supply micro-organisms to the premixer 2 and to the reactors 3 and 5.
• a supply 63 of air or oxygen is provided.
• the water taken from the premixer 2 arrives at 64. It is maintained at the temperature of 35 ° C. by means of a circulating fluid heater operating in such a way that microorganisms never pass into the fluid heater. circulation, whose internal temperature would be fatal to microorganisms.
• the three-compartment distributor 61a, 61b, 61c sends microorganisms, trace elements and nutrients to the tank 60.
• the microorganisms wake up, then develop to form a biomass whose composition will be thousands of times greater than that which is in the installation, thereby increasing the speed of degradation of the carbon chains, of the resulting COD .
• This preparation method increases the capacity of the processing unit by around 50%.
• Aeration can be replaced by bubbling or micro-oiling by means of micro-porous candles mounted on the ramps 21, by hydro-ejectors 66 which fulfill the following three functions:
• the hydro-ejector 66 shown in FIG. 5, of conventional structure comprises a centrifugal pump not shown feeding a calibrated nozzle 67 located in the center and in the axis of an annular chamber 68, an air / water mixing tube 69 and a diffuser 70.
• the assembly is completed by an atmospheric air supply pipe, an oximeter and a valve for regulating the water supply (not shown). The operation is as follows:
• the water flow generated by the pump is directed towards the hydro-ejector 66. This flow enters the body of the ejector, via the nozzle 67;
• the diffuser 70 reinforces this effect by slowing down the flow speed of the water / air assembly
• the water pump is fed by overflow so as to suck slightly below the level of the bath so that it sucks the foams that could have formed on the surface, the fats, and returns everything to the bottom of the reactor ensuring permanent mixing of the bath;
• the oximeter ensures the air suction flow so as to keep the O 2 content of the bath stable.
• Becquerels is made by fluidization in a static dryer 71, comprising no mechanical parts which could prove impossible to decontaminate at the end of the operation.
• the equipment conventionally includes (see Figure 6):
• the dryer 71 proper consists of a cylindrical body closed at its base by a perforated bottom in which are installed nozzles allowing a homogeneous distribution of the air necessary for drying;
• the expansion compartment is closed at its upper part by a curved bottom forming the roof of the dryer in which orifices equipped with sleeves and flanges allow one to evacuate the gases and the other to allow the mounting of a rod for injecting the product to be dried;
• the air necessary for operation comes from a booster and arrives in the dryer air box after being heated to 250 ° C in a circulating fluid heater;

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Biomedical Technology (AREA)
• General Health & Medical Sciences (AREA)
• Molecular Biology (AREA)
• Health & Medical Sciences (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Heat Treatment Of Water, Waste Water Or Sewage (AREA)
• Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Physical Water Treatments (AREA)
• Preparation Of Compounds By Using Micro-Organisms (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9476048

Family Applications (1)

Country Status (19)

Cited By (1)

Families Citing this family (20)

Family Cites Families (11)

• 1995
  • 1995-02-10 FR FR9501581A patent/FR2730584B1/fr not_active Expired - Fee Related
• 1996
  • 1996-02-12 KR KR1019970705491A patent/KR100301228B1/ko not_active Expired - Fee Related
  • 1996-02-12 BR BR9607727A patent/BR9607727A/pt not_active IP Right Cessation
  • 1996-02-12 EA EA199700094A patent/EA000170B1/ru not_active IP Right Cessation
  • 1996-02-12 WO PCT/FR1996/000225 patent/WO1996024937A1/fr not_active Ceased
  • 1996-02-12 SK SK1044-97A patent/SK283180B6/sk unknown
  • 1996-02-12 DE DE69602520T patent/DE69602520T2/de not_active Expired - Fee Related
  • 1996-02-12 UA UA97084143A patent/UA41438C2/uk unknown
  • 1996-02-12 US US08/875,792 patent/US5948259A/en not_active Expired - Fee Related
  • 1996-02-12 CZ CZ19972432A patent/CZ293133B6/cs not_active IP Right Cessation
  • 1996-02-12 CN CN96191883A patent/CN1173946A/zh active Pending
  • 1996-02-12 ES ES96904124T patent/ES2134593T3/es not_active Expired - Lifetime
  • 1996-02-12 CA CA002211104A patent/CA2211104C/en not_active Expired - Fee Related
  • 1996-02-12 HU HU9801212A patent/HUP9801212A3/hu unknown
  • 1996-02-12 JP JP52404996A patent/JP3256240B2/ja not_active Expired - Fee Related
  • 1996-02-12 EP EP96904124A patent/EP0808504B1/de not_active Expired - Lifetime
  • 1996-02-12 AU AU48338/96A patent/AU4833896A/en not_active Abandoned
• 1997
  • 1997-07-18 FI FI973070A patent/FI973070A7/fi unknown
  • 1997-08-06 BG BG101819A patent/BG63354B1/bg unknown

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events