Treatability Study of Mixed Waste Using Ion Exchange Resins

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Treatability Study of Mixed Waste Using Ion
Exchange Resins

• Ilham AlMahamid
• Brian M. Smith
• Lawrence Berkeley National Laboratory
• EIChroM Users Group Workshop, Pleasanton, CA,
  May 25, 1999

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Experimental Objective

• By employing innovative treatment technology,
  meet Land Disposal Restriction waste treatment
  standards and provide a disposal option for 105
  gallons of mixed waste generated by
  neutralization and consolidation of corrosive
  mixed wastes from past LBNL research.

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Waste Description

• Multiphase (solid, organic and aqueous)
• Presence of regulated metals such as chromium,
  lead and mercury at concentrations that render
  the waste combustion prohibited.
• Presence of regulated solvents such as
  chloroform, acetone, and methylene chloride that
  make combustion the appropriate treatment method.

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Waste Characterization, R12
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Waste Characterization, R12
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Waste Characterization, R13
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Waste Characterization for R13
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Waste Characterization, R21
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Waste Characterization, R21
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Experimental Approach

• Conduct a treatability study to reduce the
  concentrations of regulated metals to levels that
  would remove any combustion prohibition.
• Chromium 2.77 mg/L Note Chromium target in
• Mercury 0.15 mg/L R12 is 1,350 mg/L because
• Lead 0.69 mg/L only half of the 2,700 mg/L
• Silver 0.43 mg/L is combustion prohibited.

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METHODS

• Separate the organic layer (scrape off top)
• Separate the sludge (vacuum filtration)
• Treat the aqueous phase (resin exchange)

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Treatment of the Aqueous Phase

• Literature review of resins used to remove
  actinides and heavy metals from wastes
• Diphonix, Radaway, and apatite were selected for
  further testing

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Bench-Scale Studies

• Diphonix resin, Radaway slurry, and apatite were
  added to aliquots of the waste.
• Resin to waste ratio was 5 g / 50 mL.
• Vials were placed on a shaking table (100 rpm)
  for 24 hours at room temperature.
• Solutions were filtered and analyzed for
  actinides and metals.
• Diphonix had high uptake and was easy to handle.

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Treatment of R12

• Chromium (2,700 mg/L) was determined to be in two
  forms Cr(III) and Cr(VI) as chromate from
  chromic acid
• Precipitate chromate by addition of BaCl2.
• Reduced Cr concentration to 400 mg/Liter
• Solution turned from orange to very light yellow.
• Filtered to remove solids (barium chromate
  barium sulfate).
• Passage through the ion-exchange columns.

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Semi-Pilot Scale Treatment

• The set-up consists of
• peristaltic pump
• on-line filter
• series of six columns, three containing diphonix
  resin (cationic exchanger) and three containing
  anionic exchanger.

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Results
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Results (continued)
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Conclusions

• The treatment study removed regulated metals to
  allow combustion as a disposal option for 105
  gallons of aqueous mixed waste.
• Diphonix is useful in removal of metals and
  actinides from aqueous radioactive wastes.
• Small amounts of organics such as acetone did not
  diminish the efficiency of the resin.