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Goal II. Ensure Protective Treatment and Disposal of Mercury-Bearing Wastes
As part of this goal, EPA recently completed several mercury treatability studies to determine if alternatives to retorting, the current treatment standard for most high-mercury wastes (retorting is the thermal recovery of elemental mercury), should be allowed. Initial results of the studies indicate that mercury wastes are difficult to treat. For instance, due to a number of conditions that may exist in a hazardous or municipal landfill, these wastes can become mobile or volatile even after treatment.
To be assured of lasting, effective treatment, it may be necessary to consider site-specific factors relating to treatment and disposal. These factors include the type of mercury waste, specific treatment technology used, pH of landfill, redox conditions (conditions for reactions in which electrons are transferred) at landfill, the presence of chlorides in landfill leachate, etc. One way to allow alternatives to the retorting standard while considering such site-specific factors would be the use of variances or determinations of equivalent treatment (DETs). This would allow for site-specific factors to be considered that can affect the leachability of the mercury in the treated waste. EPA or the authorized state would work with the variance petitioner to determine the best potential treatment for the particular waste as well as which factors to consider.
As new mercury waste streams come into the regulatory system, EPA will continue to assess those streams and determine what treatment and ultimate disposal scenario will be required in order to be protective of human health and the environment. For instance, efforts to reduce mercury from electric utility power plant emissions may result in the generation of additional mercury-bearing wastes.
Projects that support this goal include the following:
Notice of Data Availability (NODA) on the Treatment of Mercury Wastes
This NODA makes publicly available two studies on the treatment of mercury wastes (68 FR 4481, January 29, 2003).The studies assess the conditions that affect the stability of waste residues resulting from the treatment of high mercury (greater than 260 mg/kg total mercury) wastes. This notice also provides information on how to use the existing treatability variance procedures to make site-specific choices on alternatives to mercury recovery.
Evaluations of Variance and Determinations of Equivalent Treatment
EPA works with mercury waste generators and treaters to evaluate variances and determinations of equivalent treatment that would allow for alternatives to retorting. For example, on October 7, 2002 (67 FR 62618), EPA published a treatability variance for the Department of Energy to treat and dispose of radioactively contaminated mercury-, cadmium-, and silver-containing batteries.