J. P. Gould

Mobilization and retention of mercury and lead from particulates co-disposed with municipal solid wastes

ABSTRACT ABSTRACT Metal sludges containing mercury and lead were codisposed among other metals with municipal solid waste in test columns (lysimeters) and leachate generation initiated by addition of water. Leachate was collected from these columns and the levels of these metals measured to provide an index of metal mobilities and mechanisms of control of those mobilities. In addition, other parameters likely to be pertinent to the mobilities of mercury and lead such as pH, ORP and inorganic anion concentrations were monitored. While efforts were also made to monitor sulfide no sulfide was detected in the leachates. The behavior of lead in these columns was consistent with precipitation by the abundant sulfate present in the leachates modified to some extent by complexation with both sulfate and chloride. The behavior of mercury was fully consistent with reduction of added mercuric to the neutral metal. While its presence could not be excluded by the data, no clear evidence of the presence of sulfide was ...

Chemical Controls on the Fate of Mercury and Lead Codisposed with Municipal Solid Waste

Mercury and lead were among several toxic metals codisposed in test lysimeters with municipal solid waste. Results of analysis of leachates from these landfills during the acid phase of landfill operation have indicated that control of mercury in these systems is a consequence of reduction of divalent mercury to neutral mercury metal. This process was found to occur whether sulfide was present or not. Dissolved mercury in these leachates will exist virtually entirely as chloride complexes. Control of lead solubility was dependent on the presence or absence of sulfide. In the presence of sulfide lead would precipitate as the sulfide while in its absence, the controlling solid was the sulfate. Soluble lead speciation involved significant fractions of both chloride and sulfate complexes. While sulfide has not been detected directly in these systems, levels necessary to control lead sOlubility were so low as to be indetectable by available methodology and thus its involvement cannot be precluded. Since some circumstantial evidence supportive of sulfate control has been obtained, the complete elucidation of chemical control mechanisms in these systems is not possible.