Linked Life Data

16830571

Source:http://linkedlifedata.com/resource/pubmed/id/16830571

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
2006-7-11
pubmed:abstractText
To evaluate the potential for in situ bioremediation of U(VI) to sparingly soluble U(IV), we constructed a pilot test facility at Area 3 of the U.S. Department of Energy Natural and Accelerated Bioremediation Research (NABIR) Field Research Center (FRC) in Oak Ridge, TN. The facility is adjacent to the former S-3 Ponds which received trillions of liters of acidic plating wastes. High levels of uranium are present, with up to 800 mg kg(-1) in the soil and 84-210 microM in the groundwater. Ambient groundwater has a highly buffered pH of approximately 3.4 and high levels of aluminum (12-13 mM), calcium (22-25 mM), and nitrate (80-160 mM). Adjusting the pH of groundwater to approximately 5 within the aquifer would deposit extensive aluminum hydroxide precipitate. Calcium is present in the groundwater at levels that inhibit U(VI) reduction, but its removal by injection of a high pH solution would generate clogging precipitate. Nitrate also inhibits U(VI) reduction and is present at such high concentrations that its removal by in situ denitrification would generate large amounts of N2 gas and biomass. To establish and maintain hydraulic control, we installed a four well recirculation system parallel to geologic strike, with an inner loop nested within an outer loop. For monitoring, we drilled three boreholes perpendicular to strike across the inner loop and installed multilevel sampling tubes within them. A tracer pulse with clean water established travel times and connectivity between wells and enabled the assessment of contaminant release from the soil matrix. Subsequently, a highly conductive region of the subsurface was prepared for biostimulation by removing clogging agents and inhibitors and increasing pH. For 2 months, groundwater was pumped from the hydraulically conductive zone; treated to remove aluminum, calcium, and nitrate, and supplemented with tap water; adjusted to pH 4.3-4.5; then returned to the hydraulically conductive zone. This protocol removed most of the aqueous aluminum and calcium. The pH of the injected treated water was then increased to 6.0-6.3. With additional flushing, the pH of the extracted water gradually increased to 5.5-6.0, and nitrate concentrations fell to 0.5-1.0 mM. These conditions were judged suitable for biostimulation. In a companion paper (Wu et al., Environ. Sci. Technol. 2006, 40, 3978-3987), we describe the effects of ethanol addition on in situ denitrification and U(VI) reduction and immobilization.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0013-936X
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3978-85
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Pilot-scale in situ bioremediation of uranium in a highly contaminated aquifer. 1. Conditioning of a treatment zone.
pubmed:affiliation
Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305-4020, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.