Original Date: 02/28/2000
Revision Date: 01/18/2007
Best Practice : Silver Recovery
Crane Army Ammunition Activity personnel improved silver recovery and eliminated hazardous waste generation with the installation of two low-cost commercial-off-the-shelf products. The payback period for this equipment was less than one year. In addition to the environmental benefits, the annual savings gave this project less than a six- month payback on expenses.
Crane Army Ammunition Activity (CAAA) personnel improved silver recovery and eliminated hazardous waste generation with the installation of two, low cost, commercial-off-the-shelf (COTS) products. In addition to the environmental benefits, the $23,421.96 annual savings gave this project less than a six-month payback on expenses. In the past, the x-ray facility, the processing of radiographic film, and the photographic processing generated 1,650 gallons of effluent annually. This effluent was considered hazardous due to its heavy metal content (silver) exceeding five parts per million. The system had an electrolytic recovery system but was unable to remove adequate contaminates, thus requiring further treatment methods. The drums of liquid hazardous waste were expensive to handle, store, and dispose by a licensed agency. CAAA develops 38,000 14" by 17" negatives annually generating 36 55-gallon drums of liquid hazardous waste which costs more than $9,900 for disposal. The labor to fill, move, store, and monitor the drums of hazardous effluent required over 100 hours of labor each year, and the lost revenue from unclaimed silver exceeded $13,000 annually as well.
A team of concerned employees identified a COTS two-stage (combined electrolytic and metallic reactive) filtration system that could remove enough metals to bring effluent below the five parts per million required by the Environmental Protection Agency (EPA) to allow effluent discharge to the local Government Owned Treatment Works. The compact units reclaim enough silver to purify the effluent, and the silver can be marketed for $4.77 per troy ounce. This two-stage filtration system was purchased for approximately $3,000 and has reduced the labor needed to collect, transport, and administer the hazardous materials saving over 100 hours per year, eliminating 30 drums of hazardous waste, and generating $12,900 in the sale of silver. In addition to the environmental considerations, this filtration method produces annual savings of $23,421.96 and has amassed a three-year savings of $70,265.88.
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