Reduction and precipitation of neptunium(V) by sulfate-reducing bacteria.

Conference · Thu Oct 21 04:00:00 EDT 1999

OSTI ID:750450

Banaszak, J E; Rittmann, B E; Reed, D T

Migration of neptunium, as NpO{sub 2}{sup +}, has been identified as a potentially important pathway for actinide release at nuclear waste repositories and existing sites of subsurface contamination. Reduction of Np(V) to Np(IV) will likely reduce its volubility, resulting in lowered subsurface migration. The ability of sulfate-reducing bacteria (SRB) to utilize Np(V) as an electron acceptor was investigated, because these bacteria are active in many anaerobic aquifers and are known to facilitate the reduction of metals and radionuclides. Pure and mixed cultures of SRB were able to precipitate neptunium during utilization of pyruvate, lactate, and hydrogen as electron donors in the presence and absence of sulfate. The neptunium in the precipitate was identified as Np(IV) using X-ray absorption near edge spectroscopy (XANES) analysis. In mixed-culture studies, the addition of hydrogen to consortia grown by pyruvate fermentation stimulated neptunium reduction and precipitation. Experiments with pure cultures of Desulfovibrio vulgaris, growing by lactate fermentation in the absence of sulfate or by sulfate reduction, confirm that the organism is active in neptunium reduction and precipitation. Based on our results, the activity of SRB in the subsurface may have a significant, and potentially beneficial, impact on actinide mobility by reducing neptunium volubility.

• Research Organization: Argonne National Lab., IL (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 750450
• Report Number(s): ANL/CMT/CP-98518
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ACTINIDES
BACTERIA
BINDING ENERGY
NEPTUNIUM
PRECIPITATION
RADIOACTIVE WASTES
RADIOISOTOPES
SULFATE-REDUCING BACTERIA
SULFATES
VALENCE