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ECONOMIC AND ENVIRONMENTAL ANALYSIS OF TECHNOLOGIES TO TREAT MERCURY AND DISPOSE IN A MONOFILL
Citation:
RANDALL, P. ECONOMIC AND ENVIRONMENTAL ANALYSIS OF TECHNOLOGIES TO TREAT MERCURY AND DISPOSE IN A MONOFILL. Presented at Mercury 2006, the Eighth International Confernce on Mercury as a Global Pollutant, Madison, WI, August 06 - 11, 2006.
Impact/Purpose:
To inform the public.
Description:
If all of the chlor alkali plants in the world shut down, it is estimated that 25-30,000 metric tons of mercury would be available worldwide. This presentation is intended to describe the economic and environmental analysis of a number of technologies for the long term management of elemental mercury. The analysis considers three treatment technologies that convert elemental mercury into a stable form of mercury. Each of the three treatment technologies is subject to a number of variations that include either a centralized treatment facility or one or more mobile treatment facilities, followed by either macroencapsulation or no macroencapsulation, with ultimate disposal in a monofill. There are twelve treatment and disposal alternatives all together. Three different masses of mercury are being considered for each of the 12 alternatives: 5,000 metric tons, 12,000 metric tons, and 25,000 metric tons. Cost estimates were prepared for storage of the three masses of elemental mercury in aboveground facilities. For the storage alternatives, it is assumed 5,000 MT is already in storage (consistent with the existing amount in government stockpiles) and that the additional elemental mercury becomes available over 12 and 25 years respectively for the 12,000 MT and 25,000 MT alternatives (e.g., due to chlor-alkali plant closure). The method chosen for the environmental comparison of the 12 alternatives is the Analytic Hierarchy Procedure (AHP). Results show mobile treatment and macroencapsulation were the most highly ranked options for both baseline analysis and 10 sensitivity analyses. The process that consistently exhibited the lowest cost was due to the lower reagent cost and the least mass increase. The cost of long-term storage is modest compared to treatment and disposal in a monofill. In addition, the scale-up performance of the treatment technologies themselves is uncertain with regard to their ability to treat relatively large quantities of mercury for an extended period of time. In all cases, good mixing and operational consistency are expected to be critical in achieving long-term stability. It is suggested to continue storing elemental mercury for a number of years or decades in anticipation that there may be an economic and performance breakthrough in treatment technologies.