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OVERVIEW OF EPA RESEARCH PROGRAM FOR HARD TO TREAT METALS - AS AND HG
Citation:
Randall*, P M. OVERVIEW OF EPA RESEARCH PROGRAM FOR HARD TO TREAT METALS - AS AND HG. Presented at EPA Workshop on Regulating and Permitting Incineration Alternatives, Salt Lake City, UT, 4/26/2001.
Description:
The DOE and the USEPA have been investigating alternatives to incineration of metals such as mercury. The DOE has significant quantities of mixed waste containing mercury and is researching alternative treatment methods. More recently, collaboration between DOE and EPA has investigated >260 ppm Hg stabilization and solidification options to current retort technology. Hard to treat metals such as Mercury and Arsenic are difficult to effectively and cheaply treat or remediate. Arsenic and mercury present special challenges for stabilization and solidification technology because of its complex chemistry and its tendency to form soluble solution species under a wide range of conditions. For example, both Arsenite and mercuric ions commonly preciptate as a sulfide which is insoluble at low pH, but more soluble under strongly basic conditions. Furthermore, cement stabilization of arsenic gives variable results. Research indicates that the arsenic catalyzes mineral respeciation which increases arsenic leaching over long cure times. Therefore, TCLP measurements of leachability will have little meaning when the cement matrix is changing over time.