Many companies have historically used carbon based adsorbents to reduce the mercury concentration in well water but are unable to utilize carbon to achieve the low levels of mercury that are now desired. Steward has conducted successful field tests at locations where new stringent mercury adsorbent targets could not be met with carbon adsorbents.
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The well water appeared dark brown in color and contained high concentrations of total dissolved solids and organics. The water also contained several unknown chemicals and more than twenty known species, such as sulfide, iron, chlorobenzene and a high concentration of humic acid. Thiol-SAMMS® (THSL) demonstrated its effectiveness to reduce mercury levels to meet the customer’s target of 90% reduction without conducting any pretreatment of their well water in a bench type treatability study. Based on the bench test results the customer set a target outgoing mercury concentration of 50 ppt for a field test.
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The client contacted Steward for support to meet their target for effluent mercury concentration levels of 1.3 ppt. The client had an existing water treatment system that reduced their mercury concentration to single ppt levels but it could not achieve their target level of 1.3 ppt or lower.
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Mercury is used in the operations of nuclear fuel processing. Much of the hazardous wastes of these processes that have been in operation since the World War II era are located at legacy sites of Department of Energy Laboratories. As a result these sites have accumulated large quantities of highly radioactive, high level mercury wastes. These legacy wastes at National Laboratories present special challenges for remediation due to contamination by radioactive elements and high organic content. They cannot be treated with normal mercury remediation methods. One widely known challenge is the V-9 tank at Idaho National Laboratory (INL).
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A refinery waste water sample was supplied to Steward. The sample had a strong odor, appeared brown-yellowish in color, and had a pH of 11. The selenium concentration was about 1 ppm. The kinetics of selenium reduction with Thiol SAMMS® (THSL) was enhanced by decreasing the pH. At pH 11 and 0.05% THSL concentration, THSL was able to reduce selenium concentration by 30% within 45 minutes. Decreasing the pH to 4.3 resulted in a further 30% selenium reduction for a total of a 60% reduction. This is possibly due to the change in selenium speciation with pH levels.
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One of Steward’s Continuous Stirred Tank Reactor (CSTR) system was utilized at a Nevada mining facility for a field test to demonstrate the use of Thiol-SAMMS® for the removal of multiple contaminants from a mining waste impoundment.
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