Grantee Research Project Results
2004 Progress Report: Microbial Reduction of Uranium in Mine Leachate by Fermentative and Iron-Reducing Bacteria
EPA Grant Number: R829515C008Subproject: this is subproject number 008 , established and managed by the Center Director under grant R829515
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Center for the Study of Metals in the Environment
Center Director: Allen, Herbert E.
Title: Microbial Reduction of Uranium in Mine Leachate by Fermentative and Iron-Reducing Bacteria
Investigators: Honeyman, Bruce D. , Spear, John R.
Institution: Colorado School of Mines
EPA Project Officer: Aja, Hayley
Project Period: November 1, 2002 through October 31, 2004
Project Period Covered by this Report: November 1, 2003 through October 31, 2004
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (2001) Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management
Objective:
The objective of this research project is to examine the use of microorganisms to remove uranium (U) from contaminated groundwater by reductive precipitation in a permeable reactive barrier (PRB). This research project explores the hypothesis that the combined metabolic activities of fermentative and iron-reducing bacteria operating in a PRB intercepting U(VI)-laden leachate will result in a U(IV) precipitate. The goal of this research project is to have this barrier technology applicable to numerous small sites as a passive technology with low impact to the site in terms of biota disturbance. This will be a remediation technology that fits into the environmental sustainability concept.
Progress Summary:
To date, various experiments have been conducted in the progress of this research project. Batch experiments have been conducted thus far as follows: (1) biotransformation of a uranium-citrate complex by Shewanella putrefaciens; (2) fate of U(VI) in the presence of calcium with Clostridium sp.; and (3) biotransformation of the uranium-citrate complex by Clostridium sp. From these experiments, both S. putrefaciens and Clostridium sp. have been found to effectively reduce U from the mobile species U(VI) to the immobile species U(IV). Various U complexes and buffers have been used in the experiments to determine the effect on microbial reduction of U. The batch systems were characterized for microbial growth and identification of dominant microbial process by direct counting, pH measurement, and high-performance liquid chromatography to identify soluble metabolites and U oxidation state by wet chemistry.
Future Activities:
We will initiate column experiments upon optimization of the batch system, using the optimal carbon source and culture conditions to examine the process under leachate flow conditions. These experiments will demonstrate the removal and stabilization of U in the column under anaerobic conditions and will quantify parameters such as flow rate, residence time, changes in permeability, U reduction efficiency over time, and kinetics of the reduction reaction. Throughout the column experiment phase, various carbon substrates will be tested, and the most effective buffer from the batch studies will be used. The column experiments will have both iron-reducing (S. putrefaciens) and fermentative (Clostridium sp.) bacteria present. Work will be done to verify the bacteria responsible for U bioreduction (i.e., 16S rRNA identification of the proportion of fermenters, iron reducers, and other microorganisms responsible for U removal) as well as to implement a pilot-scale PRB in the field. The column will be interrogated after experimentation to study the microbial population, consumption of carbon, and U speciation by wet chemistry and x-ray absorption spectrometry. A method to recover the immobilized U from the simulated PRB will be studied involving extraction with citrate that will preclude excavation of the biobarrier and allow for recovery ex situ. Co-contaminant metals such as Pb, Mo, Se, and V will be examined in select treatments for removal efficiency by the microbial consortium and potential deleterious effects on the process. The workplan for this research remains valid; planning sessions, student involvement, analytical methods, and experiment methodologies all have been established during this period, and the scope of studies is well defined.
Publications/Presentations: See the list of publications/presentations included in the 2004 Annual Report Summary for R829515, which is the overall report for the Rocky Mountain Regional Hazardous Substance Research Center.
Supplemental Keywords:
Technical Outreach Services for Communities, TOSC, Technical Assistance to Brownfields, TAB, groundwater, industry sectors, waste, water, ecological risk assessment, ecology, ecosystems, ecology and ecosystems, environmental chemistry, environmental engineering, geology, geochemistry, toxicology, microbiology, hazardous, hazardous waste, mining-NAIC 21, selenium, acid mine drainage, acid mine runoff, aquatic ecosystems, arsenic, contaminant transport, contaminated sediments, contaminated marine sediment, contaminated waste sites, contaminated sites, contaminated soil, field monitoring, mining-impacted runoff, sediment transport, stream ecosystems, suspended sediment, sediments, mining, remediation, metal mobility, subsurface, extraction of metals, heavy metals, leaching of toxic metals, metal release, metal wastes, metals, metals-contaminated soil, mining wastes, remediation technologies, risk assessment,, RFA, Industry Sectors, Scientific Discipline, Waste, TREATMENT/CONTROL, Ecosystem Protection/Environmental Exposure & Risk, Waste Treatment, Remediation, Ecosystem Protection, Restoration, Mining - NAIC 21, Ecological Effects - Environmental Exposure & Risk, Hazardous Waste, Environmental Monitoring, Bioremediation, Ecological Risk Assessment, Ecology and Ecosystems, Geology, Groundwater remediation, Hazardous, Environmental Engineering, hydrogeology, risk assessment, monitoring, aquatic ecosystem, contaminated waste sites, contaminant transport, contaminated sites, microbial degradation, permeable reactive barrier, acid mine drainage, remediation technologies, biodegradation, bioavailability, groundwater hydrology models, anaerobic biodegradation, restoration strategies, uranium, mining, hydrology, leaching of toxic metals, treatment, ecological recovery, geochemistry, in situ bioremediation, contaminated groundwater, aquatic ecosystems, environmental rehabilitation, water quality, contaminated aquifers, mining waste, extraction of metals, aquatic toxicology, ecological impact, anaerobic degradation, ecological indicators, heavy metals, mining wastes, acid mine runoff, groundwater pollution, bacterial degradation, groundwaterRelevant Websites:
http://www.engr.colostate.edu/hsrc/ Exit
Progress and Final Reports:
Original AbstractMain Center Abstract and Reports:
R829515 Center for the Study of Metals in the Environment Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R829515C001 Redox Transformations, Complexation and Soil/Sediment
Interactions of Inorganic Forms of As and Se in Aquatic Environments: Effects
of Natural Organic Matter
R829515C002 Fate and Transport of Metals and Sediment in Surface Water
R829515C003 Metal Removal Capabilities of Passive Bioreactor Systems: Effects of Organic Matter and Microbial Population Dynamics
R829515C004 Evaluating Recovery of Stream Ecosystems from Mining Pollution:
Integrating Biochemical, Population, Community and Ecosystem Indicators
R829515C005 Rocky Mountain Regional Hazardous Substance Research Center
Training and Technology Transfer Program
R829515C006 Technical Outreach Services for Communities and Technical Assistance to Brownfields
R829515C007 Evaluation of Hydrologic Models for Alternative Covers at Mine Waste Sites
R829515C008 Microbial Reduction of Uranium in Mine Leachate by Fermentative and Iron-Reducing Bacteria
R829515C009 Development and Characterization of Microbial Inocula for High-Performance Passive Treatment of Acid Mine Drainage
R829515C010 Reactive Transport Modeling of Metal Removal From Anaerobic Biozones
R829515C011 Assessment of Electrokinetic Injection of Amendments for Remediation of Acid Mine Drainage
R829515C012 Metal Toxicity Thresholds for Important Reclamation Plant Species of the Rocky Mountains
R829515C013 An Improved Method for Establishing Water Quality Criteria for Mining Impacted Streams
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.