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.

To address the high concentration of dissolved solids, Steward incorporated a pretreatment process in addition to their contactor tank systems and membranes for SAMMS retention. The field test system was designed for a flow rate of 10 gallons per minute. The pretreatment process utilized ozone prior to the series of contactor tanks to eliminate organics. In the pilot field test SAMMS was able to reduce the mercury concentration in the well water from its input level of approximately 2,000 ppt down to approximately 10 ppt output as shown in Figure 1 below. (In the figure, all data that is below the detection limit is shown as 5 ppt.) The reduction was significantly lower than the output target of 50 ppt. Over 40,000 gallons of well water were treated during the test.

FIGURE 1. Mercury Concentration

The mercury laden SAMMS adsorbent passed US Environmental Protection Agency land disposal requirements, Toxicity Characteristic Leaching Procedure (TCLP). This enables used adsorbents to be disposed of in a non-hazardous landfill where compliance with local regulations are permitted and also minimizes generating the larger volume of secondary waste.