Bi-functional Resin Groundwater Treatment at Paducah Gaseous Diffusion Plant, Kentucky

Site Name:

Paducah Gaseous Diffusion Plant



Period of

February to September 1999


Field Demonstration

Ion Exchange - Bi-functional Resin (BiQuat)
- BiQuat anion-exchange resin - trihexylammonium and triethylammonium exchange sites; designated as resin D3696 by Purolite; resin had a mesh of -25/+40 and a total anion exchange capacity of 2.0 meq/g
- Field demonstration system consisted of a resin-filled column, 12 inches long by 5.25 inches in diameter; a contingent pump was used to pump water from the bottom to the top of the column at a rate of 2.5 gallons per minute
- Column was equipped with pressure gauges at the inlet and outlet and sampling ports at the inlet, outlet, and along the column at points 1/3 and 2/3 the length of the column

Cleanup Authority:
Not provided


Gilbert M. Brown
Principal Investigator
Oak Ridge National Laboratory
Oak Ridge, TN
Telephone: (856) 576-2756
Jerry Harness
Efficient Separations
and Processing Crosscutting
Program Management
Team Lead
Oak Ridge, TN
Telephone: (865) 576-6008

- Technetium (99Tc); chemical form in oxygen-rich groundwater is the pertechnetate anion TcO4–
- Concentrations in groundwater ranged from 170 to 250 ng/L

Waste Source:
Disposal in lagoons and pits of wastes from processing uranium and plutonium

Type/Quantity of Media Treated:
- 840,000 gallons

Purpose/Significance of Application:
Field demonstration of a bi-functional resin to treat groundwater contaminated with 99Tc

Regulatory Requirements/Cleanup Goals:
- The purpose of the demonstration was to evaluate the effectiveness of BiQuat in treating groundwater contaminated with 99Tc , including assessing breakthrough, residence time, and cost

- The performance of the resin was evaluated based on pertechnetate concentrations
- Breakthrough - no breakthrough was observed in the column effluent; complete breakthrough was observed at the first sampling port on the column (1/3 column length), and 20 percent breakthrough was observed at the second sampling port (2/3 column length)
- Residence time was determined to be 27 seconds which was considered to be a very short time for complete capture of the pertechnetate
- Results also showed that the resin was particularly effective in removing low levels of pertechnetate (in the nmol/L range); BiQuat was determined to be approximately fives times more effective than the commercial Purolite A-520E resin for Tc removal

Cost Factors:
- Information about the capital costs, operating and maintenance costs, and costs of scale-up were not available
- The estimated cost of the BiQuat resin was $1,000 per cubic foot; this cost is approximately five times the cost of the commercial Purolite A-520E resin for Tc removal; however, because the BiQuat resin is about fives times more efficient than Purolite A-520E, the costs would be approximately the same for the two resins
- Resin regeneration is economically desirable, given the relatively high cost of BiQuat

At DOE’s Paducah Gaseous Diffusion Plant in Kentucky, wastewater from processing uranium and plutonium were discharged to lagoons and pits. The wastewater was frequently contaminated with Tc, and a contaminant plume is present in the sandy aquifer at the site below the vadose zone. The Tc is present in the groundwater as the pertechnetate anion, which is highly mobile. New bi-functional anion exchange resins that are highly selective for pertechnetate have been designed and are being tested as part of a research project at the Oak Ridge National Laboratory and the University of Tennessee.

A field demonstration was performed using the BiQuat anion-exchange resin, a resin containing trihexylammonium and triethylammonium exchange sites. The demonstration system included a 12 inch resin packed column with a flow rate of about 2.5 gallons per minute. The demonstration showed that the resin was effective in removing pertechnetate, especially at low levels, and that the resin was five times more efficient than the best competing resin (Purolite A-520). However, the cost of the BiQuat resin is relatively high (about $1,000 per cubic foot). A large-scale application of the technology would be needed to make the use of the resin commercially viable.