Transcript Biogeochemical Applications in Nuclear Decommissioning and

Biogeochemical Applications in Nuclear
Decommissioning and Waste Management
This project is exploring the use of microbial technologies to reduce risk of contamination from
decommissioning of nuclear sites and construction of repositories for nuclear waste. The objective is to
reduce the potential for migration of radionuclides (radioactive contaminants) in soils and rocks using
special properties of the bacteria that are naturally present in them.
Of particular interest is the ability of bacteria to form new minerals and to remove radionuclides from
solution (where they can migrate) to solid forms . The aims of the project are:
(1) To determine how micro-organisms can be used to trap radionuclides in solid forms within the soil/rock
and consequently prevent their transport to the human environment.
(2) To determine how some bacteria can be encouraged to produce minerals (e.g. calcite) in soils and rocks
that will block any pathways for fluid flow.
Radionuclide (Rn) Solid State Capture
Bacterial mechanisms under investigation
This study is investigating different bacterial
mechanisms for the removal of rn from solution,
into solid form. Our current study is comparing
uptake of strontium (Sr, a radionuclide contaminant)
by bacterially-generated hydroxyapatite (bio-HA) to
uptake by other forms of HA: chemically made, and
fish and bird bone. Uptake by bio-HA was found to
be much greater and more rapid than by other HA
forms. This is a result of bio-HA forming as much
smaller and rougher particles than the other forms,
and so has a larger surface area to react with Sr
(A)
Uranyl phosphate
precipitated on a
bacterium
Uranium in solution
(r) is reduced by
bacteria to form a
precipitate (l)
(B)
Electron micrographs of chemical HA (l) and Bio-HA (r)
Clogging of Fluid Pathways
Bacteria can breakdown urea, releasing
carbonate and, when calcium is present,
precipitating the mineral calcite. This
study will be investigating the use of
bacterial calcite formation to clog
fractures in rock and hence limit fluid
flow through the fracture.
When applied to contaminated environments, the consequent reduction in permeability of the host rock
is intended to prevent radionuclide migration long enough to allow development of a substantial
engineering solution.
Researchers: R. Mackay, M. Riley, M. Cuthbert, S. Handley-Sidhu, L. E. Macaskie, J. C Renshaw
College of Life, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham
Contacts: Rae Mackay, [email protected]; Joanna Renshaw, [email protected]
Collaborating Institutes