Improved Process Used to Treat Aqueous Mixed Waste Results in Cost Savings and Improved Worker Safety
- Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)
This paper describes an improved process implemented at Argonne National Laboratory (ANL) to treat aqueous mixed waste. This waste is comprised of radioactively-contaminated corrosive liquids with heavy metals. The Aqueous Mixed Waste Treatment System (AMWTS) system components include a reaction tank and a post-treatment holding tank with ancillary piping and pumps; and a control panel with pumping/mixing controls; tank level, temperature and pH/Oxidation Reduction Potential (ORP) indicators. The process includes a neutralization step to remove the corrosive characteristic, a chromium reduction step to reduce hexavalent chromium to trivalent chromium, and a precipitation step to convert the toxic metals into an insoluble form. Once the toxic metals have precipitated, the resultant sludge is amenable to stabilization and can be reclassified as a low-level waste if the quantity of leachable toxic metals, as determined by the TCLP, is below Universal Treatment Standards (UTS). To date, six batches in eight have passed the UTS. The AMWTS is RCRA permitted and allows for the compliant treatment of mixed waste prior to final disposal at a Department of Energy (DOE) or commercial radioactive waste disposal facility. Mixed wastes eligible for treatment include corrosive liquids (pH <2 or >12.5) containing EPA-regulated toxic metals (As, Ba, Pb, Cd, Cr, Ag, Se, Hg) at concentrations greater than the RCRA Toxicity Characteristic Leaching Procedure (TCLP) limit. The system has also been used to treat corrosive wastes with small quantities of fissionable materials. The AMWTS is a significant engineered solution with many improvements over the more labor intensive on-site treatment method being performed within a ventilation hood used previously. The previously used treatment system allowed for batch sizes of only 15-20 gallons whereas the new AMWTS allows for the treatment of batches up to 75 gallons; thereby reducing batch labor and supply costs by 40-60% and reducing analytical testing costs by 50-75%. Reduced treatment time also reduces worker radiation exposure to As Low As Reasonably Achievable (ALARA) levels. Additionally, the treatment system components used previously were adapted to be used with the new AMWTS. This allowed for less dependence on personnel protective equipment (PPE) than the prior system by separating the waste handling/bulking steps of the process from the treatment steps. The AMWTS also improved worker safety by incorporating more automated engineering controls such as system logic controls; personnel safety and equipment protection interlocks, off normal condition indicators/alarms, and system emergency stop controls. In a time of ever-decreasing budgets, it makes sense to rethink the use of existing treatment systems. Utilizing, and possibly retooling, equipment and infrastructure may allow for reduced treatment costs and increase worker safety. (authors)
- Research Organization:
- WM Symposia, Inc., PO Box 13023, Tucson, AZ, 85732-3023 (United States)
- OSTI ID:
- 21208555
- Report Number(s):
- INIS-US-09-WM-06012; TRN: US09V0865079342
- Resource Relation:
- Conference: Waste Management 2006 Symposium - WM'06 - Global Accomplishments in Environmental and Radioactive Waste Management: Education and Opportunity for the Next Generation of Waste Management Professionals, Tucson, AZ (United States), 26 Feb - 2 Mar 2006; Other Information: Country of input: France
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANL
CHROMIUM COMPOUNDS
CORROSIVE EFFECTS
FISSIONABLE MATERIALS
HEAVY METALS
LIQUID WASTES
LOW-LEVEL RADIOACTIVE WASTES
OCCUPATIONAL SAFETY
PERSONNEL
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE PROCESSING
TANKS
TOXICITY
US EPA