Physical-Chemical Treatment of Metals and Radionuclides in the Saturated Zone Using Colloidal Buffers - 12515

Conference · Sun Jul 01 04:00:00 EDT 2012

OSTI ID:22293729

Lai, Yenjung; Borden, Robert C. ^[1]; Alperin, Ed ^[2]

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1. North Carolina State University, Raleigh, NC 27695 (United States)
2. EOS Remediation, LLC. Raleigh, NC 27607 (United States)

There are numerous acidic plumes throughout the DOE complex and the nation as a whole. Low aquifer pH is a major concern since many important radionuclides (Pu, Ra, Sr, Tc) and metals (Cd, Co, Cs, Mn, Ni, Pb, Zn) strongly sorb to iron hydroxides and aluminosilicates under neutral to alkaline conditions, but are mobile in acidic plumes. To effectively use natural and enhanced attenuation (NEA) for management of these contaminants, we must be able to raise aquifer pH and maintain it at background levels until the external acid loading to the aquifer has dissipated. Geochemical modeling showed that a permeable reactive barrier (PRB) formed by injection of colloidal Mg(OH){sub 2} would last much longer than colloidal Ca(OH){sub 2} due to the much lower solubility of Mg(OH){sub 2}. Assuming a 1,000 meq/L suspension of colloidal Mg(OH)2 could be effectively distributed, the PRB could last over twenty years before rejuvenation was required. Preliminary bench-scale treatability studies were conducted to demonstrate the efficacy of increasing the aquifer pH using a colloidal pH buffer. Laboratory studies demonstrated that three different colloidal Mg(OH){sub 2} suspensions (concentration varied from 1,000 to 1,250 meq/L) could be transported through the columns packed with aquifer sand without significant permeability loss. The time before suspension breakthrough into the column effluent varied with surface treatment, indicating the Mg(OH)2 retention and PRB longevity could be controlled by varying the suspension surface treatment. (authors)

• Research Organization: WM Symposia, 1628 E. Southern Avenue, Suite 9-332, Tempe, AZ 85282 (United States)
• OSTI ID: 22293729
• Report Number(s): INIS-US--14-WM-12515
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
IRON HYDROXIDES
MAGNESIUM HYDROXIDES
MANAGEMENT
METALS
RADIOISOTOPES
SIMULATION
SUSPENSIONS