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Número de publicaciónWO2009129184 A1
Tipo de publicaciónSolicitud
Número de solicitudPCT/US2009/040372
Fecha de publicación22 Oct 2009
Fecha de presentación13 Abr 2009
Fecha de prioridad18 Abr 2008
Número de publicaciónPCT/2009/40372, PCT/US/2009/040372, PCT/US/2009/40372, PCT/US/9/040372, PCT/US/9/40372, PCT/US2009/040372, PCT/US2009/40372, PCT/US2009040372, PCT/US200940372, PCT/US9/040372, PCT/US9/40372, PCT/US9040372, PCT/US940372, WO 2009/129184 A1, WO 2009129184 A1, WO 2009129184A1, WO-A1-2009129184, WO2009/129184A1, WO2009129184 A1, WO2009129184A1
InventoresJames Spain
SolicitanteBasin Water, Inc.
Exportar citaBiBTeX, EndNote, RefMan
Enlaces externos:  Patentscope, Espacenet
Radium removal and disposal
WO 2009129184 A1
Resumen
The disclosed invention relates to the removal and disposal of radium present in potable water sources.
Reclamaciones  (El texto procesado por OCR puede contener errores)
WHAT IS CLAIMED IS:
1. A process for removing radium from radium-contaminated water comprising:
in a contacting zone contacting the radium-contaminated water with a strong acid cation exchange resin under radium-exchanging conditions thereby forming a reduced radium content water and a radium-containing strong acid cation exchange resin; continuing to contact additional radium-contaminated water with the radium- containing strong acid cation exchange resin under radium-exchanging conditions thereby forming additional reduced radium content water and an enhanced radium content radium- containing strong acid cation exchange resin, until the radium content of the enhanced radium content radium-containing strong acid cation exchange resin approaches but does not exceed 200 pCi/g; halting the contacting of radiation-contaminated water with the enhanced radium content radium containing strong acid cation exchange resin; recovering the enhanced radium content radium-containing strong acid cation exchange resin having a radium content approaching but not exceeding 200 pCi/g from the contacting zone; admixing and encapsulating the recovered enhanced radium content radium- containing strong acid cation exchange resin with mineral-based material which forms a solid body comprising encapsulated enhanced radium content radium-containing strong acid cation exchange resin wherein said radium does not leach form the solid body under storage conditions; and disposing of the solid bodies of encapsulated enhanced radium content radium-containing strong acid cation exchange resin in a land fill.
2. The process of claim 1 wherein the strong acid cation exchange resin is present in the contacting zone as a bed and wherein the radium-exchanging conditions include flow contact of the radium-contaminated water with the resin bed.
3. The process of claim 1 wherein the strong acid cation exchange resin is a macroreticular resin.
4. The process of claim 3 wherein the macroreticular resin is a styrene -based resin.
5. The process of claim 4 wherein the styrene-based macroreticular resin is a sulfonate-containing cross-linked resin.
6. The process of claim 1 wherein the mineral-based material comprises clay.
7. The process of claim 6 wherein the encapsulating comprises dewatering the mineral-based material after admixing.
8. The process of claim 1 wherein the radium-contaminated water has a pH of about
5.5.
9. The process of claim 8 wherein the radium-contaminated water additionally comprises iron ions.
Descripción  (El texto procesado por OCR puede contener errores)

RADIUM REMOVAL AND DISPOSAL

Field of the Invention

[0001] This invention relates to the removal and disposal of radium present in potable water sources.

Background and State of the Art

[0002] Most drinking water sources have very low levels of radioactive contaminants ("radionucleotides"). Radium is one of these radionucleotides. Much of this contamination is naturally occurring. In most cases these radionucleotide contaminants are at levels that are low enough to not be considered a health concern. At higher levels radionucleotides in drinking water may cause cancer.

[0003] To protect public health, the EPA has established a drinking water standard for radium. This standard (5 pCi/L) is expressed in terms of the picoCuries of radiation given off by the radium present per liter of drinking water. A range of water sources have been found to exceed this action level. Either the radium levels are reduced to below this level or the water source can not be used as potable water.

[0004] A number of processes have been proposed or implemented to remove radium from water and thus to reduce the level to below 5 pCi/L. The USEPA has classified a variety of water softening treatments as Best Available Technologies ("BAT's"). These have included lime softening, ion exchange and reverse osmosis. As a general rule, technologies which remove magnesium and calcium during water softening also remove radium. Absorption of radium onto hydrous manganese oxide ("HMO") is also promoted as a way to remove radium from drinking water.

[0005] Dow markets a special ion exchange resin product under the tradename DOWEX RSC, where "RSC" is an abbreviation for "Radium Selective Complexer". This is a barium sulfate-doped styrene resin. As its name suggests, DOW RSC selectively removes radium and leaves calcium, magnesium and other hardness ions in the water. This resin is not regenerable and in some settings needs a significant level of sulfate, such as up to about 30 parts per million, in the water being treated to have a long resin life. In addition, use of DOW RSC is incompatible with low pH water sources such as water sources at pH 5.5 or lower. As with many resins, iron contamination in the water supplies can shorten the effective resin life.

[0006] The DOWEX RSC resin is relatively expensive and thus is commonly operated for long periods. This long run cycle leads to the accumulation of large enough amounts of radium on the resin that when it is removed from service it must be treated as a hazardous radioactive material and thus must be discarded into a "low level radioactive material disposal" site. The cost of such disposal is very high, currently at least $225 per Ib. This is as much or more than the cost of the fresh resin itself. This leads to a non economic operation.

Summary of the Invention

[0007] A new process for removing radium from a radium-contaminated water source intended for use as potable water has now been found. In one aspect, this invention relates to a process for removing radium from radium-contaminated water, which process comprises:

in a contacting zone contacting the radium-contaminated water with a strong acid cation exchange resin under radium-exchanging conditions thereby forming a reduced radium content water and a radium-containing strong acid cation exchange resin;

continuing to contact additional radium-contaminated water with the radium-containing strong acid cation exchange resin under radium-exchanging conditions thereby forming additional reduced radium content water and an enhanced radium content radium-containing strong acid cation exchange resin, until the radium content of the enhanced radium content radium-containing strong acid cation exchange resin approaches but does not exceed 200 pCi/g; halting the contacting of radiation-contaminated water with the enhanced radium content radium containing strong acid cation exchange resin; recovering the enhanced radium content radium-containing strong acid cation exchange resin having a radium content approaching but not exceeding 200 pCi/g from the contacting zone; admixing and encapsulating the recovered enhanced radium content radium- containing strong acid cation exchange resin with mineral-based material and forming solid bodies of encapsulated enhanced radium content radium-containing strong acid cation exchange resin; and disposing of the solid bodies of encapsulated enhanced radium content radium-containing strong acid cation exchange resin in a land fill. [0008] This and other embodiments are further described in the text that follows.

Detailed Description of the Invention

[0009] This process of the invention contacting radium-contaminated water with a strong acid cation exchange resin under radium exchanging conditions. This contacting is carried out in a contacting zone. This contacting results in the formation of a reduced radium content water and a radium-containing strong acid cation exchange resin.

[0010] This contacting is continued as additional radium-contaminated water is brought into contact with the radium-containing strong acid cation exchange resin. This gives rise to the formation of additional reduced radium content water and an enhanced radium content radium-containing strong acid cation exchange resin. The contacting is stopped when the radium content of the enhanced radium content radium-containing strong acid cation exchange resin approaches but does not exceed 200 pCi/g. At this point the enhanced radium content radium-containing strong acid cation exchange resin is recovered from the contacting zone.

[0011] The recovered enhanced radium content radium-containing strong acid cation exchange resin having a radium content approaching but not exceeding 200 pCi/g is then admixed and encapsulated with mineral-based material and formed into solid bodies of encapsulated enhanced radium content radium-containing strong acid cation exchange resin.

[0012] These solid bodies are disposed of in a land fill. [0013] As used herein, the term "strong acid cation exchange resins" refer to polymeric resins having acid groups with a pka of less than 4, preferably less than 3, more preferably less than 2 and most preferably less than 1, attached thereto, wherein the acid group is neutralized to an acid metal salt such as an alkali or alkaline metal salt. Preferred salts include sodium, potassium, calcium and the like. Preferred polymeric resins include polystyrene resin and preferred acid groups include sulfonic acid groups. Preferred resins are highly crosslinked, macroporous strong acid cation exchange resin based on sulfonated polystyrene, crosslinked with divinylbenzene and are available from Resintech, West Berlin, NJ, USA under the tradename SACMP.

[0014] Accordingly, in one aspect, this invention relates to a process comprising

in a contacting zone contacting the radium-contaminated water with a strong acid cation exchange resin under radium-exchanging conditions thereby forming a reduced radium content water and a radium-containing strong acid cation exchange resin; continuing to contact additional radium-contaminated water with the radium- containing strong acid cation exchange resin under radium-exchanging conditions thereby forming additional reduced radium content water and an enhanced radium content radium- containing strong acid cation exchange resin, until the radium content of the enhanced radium content radium-containing strong acid cation exchange resin approaches but does not exceed 200 pCi/g; halting the contacting of radiation-contaminated water with the enhanced radium content radium containing strong acid cation exchange resin; recovering the enhanced radium content radium-containing strong acid cation exchange resin having a radium content approaching but not exceeding 200 pCi/g from the contacting zone; admixing and encapsulating the recovered enhanced radium content radium- containing strong acid cation exchange resin with mineral-based material and forming solid bodies of encapsulated enhanced radium content radium-containing strong acid cation exchange resin; and disposing of the solid bodies of encapsulated enhanced radium content radium-containing strong acid cation exchange resin in a land fill. [0015] In some embodiments, the strong acid cation exchange resin is present in the contacting zone as a bed and wherein the radium-exchanging conditions include flow contact of the radium-contaminated water with the resin bed.

[0016] In some embodiments, the strong acid cation exchange resin is a macroreticular resin. In some embodiments, the macroreticular resin is a styrene -based resin. In some embodiments, the styrene-based macroreticular resin is a sulfonate-containing cross-linked resin.

[0017] In some embodiments, the mineral-based material comprises clay.

[0018] In some embodiments, the contacting is stopped when the radium content of the enhanced radium content radium-containing strong acid cation exchange resin is greater than about 100 pCi/g. In some embodiments, the contacting is stopped when the radium content of the enhanced radium content radium-containing strong acid cation exchange resin is greater than about 150 pCi/g. In some embodiments, the contacting is stopped when the radium content of the enhanced radium content radium-containing strong acid cation exchange resin is greater than about 180 pCi/g. In some embodiments, the contacting is stopped when the radium content of the enhanced radium content radium-containing strong acid cation exchange resin is greater than about 190 pCi/g. In all cases, the radium content of the enhanced radium content radium-containing strong acid cation exchange resin does not exceed 200 pCi/g.

[0019] In some embodiments, the encapsulating causes substantially all enhanced radium content radium-containing strong acid cation exchange resin is encapsulated in mineral- based material and forms solid bodies.

[0020] In some embodiments, a greater than about 60% of the enhanced radium content radium-containing strong acid cation exchange resin is encapsulated in mineral-based material and forms solid bodies. In some embodiments, a greater than about 80% of the enhanced radium content radium-containing strong acid cation exchange resin is encapsulated in the mineral-based material and forms solid bodies. In some embodiments, a greater than about 90% of the enhanced radium content radium-containing strong acid cation exchange resin is encapsulated in mineral-based material and forms solid bodies. In some embodiments, a greater than about 95% of the enhanced radium content radium- containing strong acid cation exchange resin is encapsulated in the mineral-based material and forms solid bodies.

[0021] In some embodiments, the encapsulating comprises dewatering the mineral-based material after admixing.

[0022] In some embodiments, the radium-contaminated water has a pH of about or below 5.5. In some embodiments, the radium-contaminated water has a pH of about 5.5.

[0023] In some embodiments, the radium-contaminated water additionally comprises iron ions.

[0024] In another embodiment, the invention provides a process comprising:

contacting the radium-contaminated water with a strong acid cation exchange resin under radium-exchanging conditions thereby forming a reduced radium content water and a radium-containing strong acid cation exchange resin; halting the contacting of radiation-contaminated water with the radium containing strong acid cation exchange resin; recovering the radium-containing strong acid cation exchange resin; encapsulating the recovered radium-containing strong acid cation exchange resin with mineral-based material and forming solid bodies of encapsulated radium- containing strong acid cation exchange resin; wherein the solid bodies are safe for being disposed in a land fill.

Example

[0025] The following example is provided to illustrate certain aspects of the present invention and to aid those of skill in the art in practicing the invention. The example is in no way to be considered to limit the scope of the invention.

[0026] In this example, a strong acid cation exchange resin such as SACMP from Resintech, West Berlin, New Jersey, U.S.A, is placed in a vessel. The radium- contaminated water is allowed to flow through the vessel comprising the resin under radium-exchanging conditions at a flow rate of 10-12 gallons per minute per square foot of vessel cross-sectional area under ambient conditions. The water effluent from the contacting zone preferably has a reduce radium level of less than 5 picocuries per liter (pCi/L). The process is continued until the radium absorbed by the resin reaches a concentration of 200 picocuries per gram (pCi/g) of resin.

[0027] The water flow is then halted and the radium-containing strong acid cation exchange resin is recovered from the vessel. The discarded resin is encapsulated into a clay molding suitable for retaining the radium in situ without leaching. The clay molding is then placed in a suitable landfill.

Citas de patentes
Patente citada Fecha de presentación Fecha de publicación Solicitante Título
US4800024 *4 Ago 198624 Ene 1989Iso-Clear Systems CorporationRemoval of heavy metals and heavy metal radioactive isotopes from liquids
Clasificaciones
Clasificación internacionalC02F1/42
Clasificación cooperativaC02F2101/006, C02F1/42, C02F2001/425
Clasificación europeaC02F1/42
Eventos legales
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