1. 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

2. 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.

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

4. Waste Characterization, R12

6. Waste Characterization, R13

7. Waste Characterization for R13

8. Waste Characterization, R21

10. Experimental Approach Conduct a treatability study to reduce the concentrations of regulated metals to levels that would remove any combustion prohibition. n Chromium2.77 mg/L Note: Chromium target in n Mercury0.15 mg/L R12 is 1,350 mg/L because n Lead0.69 mg/L only half of the 2,700 mg/L n Silver0.43 mg/L is combustion prohibited.

11. METHODS n Separate the organic layer (scrape off top) n Separate the sludge (vacuum filtration) n Treat the aqueous phase (resin exchange)

12. Treatment of the Aqueous Phase n Literature review of resins used to remove actinides and heavy metals from wastes n Diphonix, Radaway, and apatite were selected for further testing

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

14. Treatment of R12 n Chromium (2,700 mg/L) was determined to be in two forms: Cr(III) and Cr(VI) as chromate from chromic acid n Precipitate chromate by addition of BaCl 2. n Reduced Cr concentration to ~400 mg/Liter n Solution turned from orange to very light yellow. n Filtered to remove solids (barium chromate+ barium sulfate). n Passage through the ion-exchange columns.

15. 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.

17. Results

18. Results (continued)

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