• Effective against a wide range of heavy metals, chlorinated compounds, and other contaminants. See Bench test results on  removal of metals from groundwater contaminated by Zinc Smelter.
• Converts hexavalent and trivalent chromium to chromium hydroxide in a one-step reaction. See Overall Effectiveness of Water Treatment Process for Cr(III) and Cr(VI) and Summary of Studies on Cr(VI) Reduction by Calcium Polysulfide.
  
• Delivers more stability in subsurface environments than other reductants, such as sodium dithionite. See In-Situ Remediation of a Chromium-Contaminated Site Using Calcium Polysulfide.
• Provides greater persistence and lateral transport away from injection wells because of its slower reaction rates. See Successful In-Situ Chemical Reduction of High Explosives in Groundwater.
• May be applied to in-situ and ex-situ media.
• NSF approved for ANSI Standard 60 drinking water treatment.

Calcium Polysulfide is fairly safe to handle out in the field. It is a non-toxic remedial amendment that oxidizes under aerobic conditions to form calcium, elemental sulfur and sulfate. Numerous applications have been conducted successfully at various industrial remediation and mining reclamation sites over the past 40 years, and no detrimental impact to the environment and public health and safety have been observed. Calcium Polysulfide is also widely used in agricultural applications on fruit trees, grapes and berries, and as a soil amendment for treating sodic and saline-sodic soils. See Calcium Polysulfide as Agricultural Soil Amendment.

When introduced into the environment, Calcium Polysulfide dissociates to form bisulfide, aqueous hydrogen sulfide and other sulfur compounds. Heavy metal ions are precipitated as less soluble, less toxic metal sulfides by these breakdown products. Metal hydroxides change solubility with changes in pH, whereas metal sulfides remain insoluble within a wide pH range. See Solubility of Metal Hydroxides and Sulfides as a Function of pH.  

While effective treatment by Calcium Polysulfide can be achieved over a wide pH range, best results are typically obtained within pH 7-10. Adjustments to the pH of the treatment system can enhance the metal precipitation process. See pH Guidelines for Treatment of Soluble Metal Streams.