Highly Efficient Removal of Mercury from Industrial Flue Gas

This Phase I SBIR project focuses on a technology that potentially reduces volatile metal mercury (Hg) emissions by approximately 95 percent from coal-fired utilities. Frontier GeoSciences, Inc., has discovered a method of removing Hg by chemically modifying scrubber water with a proprietary polymer (Frontier GeoSciences’ toxic metal chelating agent; FGS-MCX). Scrubber water naturally removes Hg species that are water soluble (e.g., MMHg and HgCl2), but this project focuses on Hg0. The complexed Hg easily separates from the scrubber water allowing the recycling of the scrubber water without additional treatment for toxic metals. The use of FGS-MCX as a wet scrubber amendment requires no additional equipment, thereby reducing capital and implementation costs. The resulting solid passes all required Toxicity Characteristic Leaching Procedure (TCLP) requirements. Hg is recognized as a hazardous air pollutant and persistent bioaccumulative toxic chemical, and its pollution through air emissions is regulated by the 2005 U.S. Environmental Protection Agency Clean Air Mercury Rule. The Clean Air Mercury Rule regulates Hg emissions from new and existing coal-fired power plants by establishing a maximum national emissions level and imposing a cap-and-trade system. In an ideal situation, Hg would not be used in raw materials; unfortunately, this is not feasible currently, and the easiest locations for Hg capture are flue gas dischargers. Previous research on FGS-MCX has shown that it successfully removes approximately 95 percent Hg0 from a contaminated N2 gas stream and greater than 86 percent removal of Hg from a simulated flue gas stream when tested in an impinger/bubbler system. The optimal dosing amount of FGS-MCX, the effects of scrubber water volume and pH, and the ability to recycle materials already have been studied. This technology will be a real-scale working Venturi wet scrubber system in the presence of common matrix components of typical scrubber water, such as is found in a flue gas desulfurization unit. Other goals include establishing the length of time the scrubber water and FGS-MCX can be recycled before exhaustion, and maximizing the separation efficiency of the FGS-MCX floc from scrubber water. Finally, Hg0 removal from natural gas, by the FGS-MCX amendment, will be demonstrated as a potential application for the petroleum industry. As there is no capital equipment expenditure required, it is envisioned that the technology will, at a minimum, pay for itself through the production of salable mercury credits.