Literature study on the breakdown of bitumen by microorganisms

Bitumen is used for conditioning of low and intermediate level radioactive wastes. The matrix material used has to guarantee, together with other safety barriers, that the radioactive material is safely retained in the repository over a prolonged period of time and is not released to the environment. It is known that bitumen is relatively resistent to the processes of decomposition. However, in the presence of certain environmental conditions decay or decomposition of bitumen can take place. Organisms that are responsible for such activities can be found more or less everywhere. The work published so far contains only few data on decomposition rate and gas formation in bitumen. For a better understanding of these processes for environmental conditions and storage periods that are relevant for waste disposal sites, additional investigations seem to be necessary. (author)