Evaluation of the potential of biodegradation for the disposal of cutting fluid from the machining of uranium

The disposal of used cutting fluid from the machining of uranium is problem atical. Biodegradation offers the potential to convert this material into f orms amenable to disposal as low level radioactive waste. The real bonus of biodegradation for radioactive applications crucially depends on the degre e of mineralisation achieved. In non-radioactive trials using a consortium of bacteria selected from used cutting fluid, only 33% of the organic carbo n was converted to carbon dioxide, even though 90% of the principal compone nt (hydrocarbons) was biodegraded. Intermediate degradation products (ident ified as naphthenic acids) accumulated. Downstream processing of the biotre ated fluid by ultrafiltration and adsorption onto activated charcoal produc ed a waste stream that would qualify as aqueous radioactive waste. Separate d biomass was immobilised in a cement matrix that would qualify as solid ra dioactive waste, albeit in a volume which would make the overall process in efficient. Future work to optimise the process is proposed. Crown Copyright (C) 2001 Published by Elsevier Science Ltd. All rights reserved.