POTENTIAL USE OF ACTIVATED CARBON TO RECOVER TC-99 FROM 200 WEST AREA GROUNDWATER AS AN ALTERNATIVE TO MORE EXPENSIVE RESINS HANFORD SITE RICHLAND WASNINGTON

Recent treatability testing performed on groundwater at the 200-ZP-1 Operable Unit at the Hanford Site in Richland, Washington, has shown that Purolite{reg_sign} A530E resin very effectively removes Tc-99 from groundwater. However, this resin is expensive and cannot be regenerated. In an effort to find a less expensive method for removing Tc-99 from the groundwater, a literature search was performed. The results indicated that activated carbon may be used to recover technetium (as pertechnetate, TCO{sub 4}{sup -}) from groundwater. Oak Ridge National Laboratory used activated carbon in both batch adsorption and column leaching studies. The adsorption study concluded that activated carbon absorbs TCO{sub 4}{sup -} selectively and effectively over a wide range of pH values and from various dilute electrolyte solutions (< 0.01 molarity). The column leaching studies confirmed a high adsorption capacity and selectivity of activated carbon for TCO{sub 4}{sup -}. Since activated carbon is much less expensive than Purolite A530E resin, it has been determined that a more extensive literature search is warranted to determine if recent studies have reached similar conclusions, and, if so, pilot testing of 200-ZP-1 groundwater wi11 likely be implemented. It is possible that less expensive, activated carbon canisters could be used as pre-filters to remove Tc-99, followed by the use of the more expensive Purolite A530E resin as a polishing step

SGW-35753-FP Revision 0 Treatability Test for Removing Technetium-99 from 200-ZP-1 Groundwater, Hanford Site FLUOR" Approved for Public Release; Further Dissemination UnlL'TIited Treatability Test for Removing Technetium-99 from 200-ZP-1 Groundwater, Hanf

ABSTRACT The 200-ZP-I Groundwater Operable Unit (OU) is one of two groundwater OUs located within the 200 West groundwater aggregate area of the Hanford Site. The primary risk-driving contaminants within the 200-ZP-I OU include carbon tetrachloride and technetium-99 (Tc-99). A pump-and-treat system for this OU was initially installed in 1995 to control the 0.002 kg 1m 3 (2000 IlgIL) contour of the carbon tetrachloride plume. Carbon tetrachloride is removed from groundwater with the assistance of an air-stripping tower. Ten extraction wells and three injection wells operate at a combined rate of approximately 0.017m 3/s (17.03 Lis). In 2005, groundwater from two of the extraction wells (299-WI5-765 and 299-WI5-44) began to show concentrations greater than twice the maximum contaminant level (MCL) ofTc-99 (33,309 beq/nr' or 900 pCi/L). The Tc-99 groundwater concentrations from all ten of the extraction wells when mixed were more than one-half of the MCL and were slowly increasing. If concentrations continued to rise and the water remained untreated for Tc-99, there was concern that the water re-injected into the aquifer could exceed the MCL standard. Multiple treatment technologies were reviewed for selectively removing Tc-99 from the groundwater. Of the treatment technologies, only ion exchange was determined to be highly selective, commercially available, and relatively low in cost. Through research funded by the U.S. Department of Energy, the ion-exchange resin Purolite® A-530E 1 was found to successfully removeTc-99 from groundwater, even in the presence of competing anions. For this and other reasons, Purolite® A-530E ion exchange resin was selected for treatability testing. The treatability test required installing resin columns on the discharge lines from extraction wells 299-W15-765 and 299-WI 5-44. Preliminary test results have concluded that the Purolite" A-530E' resin is effective at removing Tc-99 from groundwater to below detection limits even in the presence of competing anions (e.g., nitrate and sulfate) at concentrations five to six magnitudes higher than Tc-99. 'PuroHte"' A-530E is a registered trademark of the Purolite Company

The nitrogen cycle in terrestrial ecosystems

Ann McNeill, Murray Unkovichhttp://www.springer.com/life+sci/ecology/book/978-3-540-68026-