Enzymatic degradation of plutonium-contaminated cellulose products Page: 5 of 15
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contaminated waste paper are generated every year at Los Alamos. The variety of other
materials of contaminated or suspect waste includes rubber, lead, laboratory clothing and
supplies, laboratory and other equipment and anything else that might have come in
contact with radioactive materials. Historic or legacy waste of such materials is
currently stored on DOD or DOE facilities. It has been estimated that 275,000 55-gallon
drums of such waste currently is awaiting disposal. From Los Alamos National
Laboratory's facility TA-55 alone, 55 kg of cellulose waste is currently generated every
Currently the TRU waste products are slated for disposal at the WIPP (Waste
Isolation Pilot Plant) facility located in New Mexico, but opposition from various groups
has prevented the use of this completed facility, so the materials remain on the
governmental defense reservations. Even when (if) this or a similar facility can begin
accepting TRU waste, it will be expensive to store such items in perpetuity. The same
argument can be made for the disposal of LLW in appropriate facilities. Therefore, any
technology that can reduce the volume of such wastes would greatly reduce the cost of
disposal and the associated risk of potential human and environmental contamination.
The use of industrial-strength enzyme solutions developed and marketed for a
variety of other applications may be useful in the reduction in volume of radionuclide-
contaminated wastes. Unlike many enzymes used in research projects, most industrial
enzyme preparations are able to withstand (and function under) harsh conditions of use
such as low or high pHs and in the presence of detergents or heavy metals. A technology
based on the use of industrial cellulases developed to treat oil-saturated cotton sorbents in
the presence of seawater previously was found to be useful for degrading uranium-
contaminated cotton fabrics, releasing the uranium into the enzyme solution (U.S. Pat.
The present project was intended to demonstrate the feasibility of this process for
treatment of cellulose-containing materials in LANL's laboratory waste stream. Dr. Jim
Brainard and associates at LANL who used a microbial source of enzymes rather than the
enzymes alone have proved this technology with Pu-treated cotton. The current report
describes the use of RapidaseTm, an industrially-available cellulase, to degrade
contaminated cellulose substrates, releasing a portion of the radioactivity into the enzyme
solution from which it can be recovered more readily than from a solid matrix. The
residue from the enzyme treatment, which still is contaminated with radionuclides, was
greatly reduced in weight and volume after 6 days of treatment. Further reduction is
possible with extended or repeated treatment.
Degradation of raw cotton intentionally contaminated with known levels of
plutonium oxides or non-radioactive lanthanide surrogates including cerium oxide,
cerium carbonate and praseodymium oxide was evaluated. Initial experiments were
performed with various forms of cotton (raw, cleaned, scoured and bleached and
manufactured items) to define the conditions needed by the enzyme, as supplied by the
manufacturer, to degrade both the non-contaminated and contaminated cellulose-
containing items. Next, cotton contaminated with lanthanides, then with plutonium was
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Heintz, C.E.; Rainwater, K.A.; Swift, L.M.; Barnes, D.L.; Worl, L. & Avens, L. Enzymatic degradation of plutonium-contaminated cellulose products, article, March 1, 1999; New Mexico. (digital.library.unt.edu/ark:/67531/metadc674992/m1/5/: accessed January 21, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.