Superfund Research Program
On Site Mercury Remediation via Activated Fly Ash
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Mercury (Hg) is one of the most harmful and toxic pollutants to humans, and it is predominantly introduced into the environment in vapor form from burning fossil fuels. Fossil fuel consumption results in ever-higher mercury concentrations in the air, water, soil, and, ultimately, in food that humans consume. The U.S. Environmental Protection Agency (EPA) estimates that mercury instigated healthcare costs range between $37-90 billion dollars annually. Recently, the EPA has instituted much stricter mercury emission regulations (effective April 16, 2015) that set a mercury emissions cap between 1.2-4 pounds of Hg per trillion British Thermal Units depending on the coal rank for all existing electrical generating units. These regulations have created a significant economic and technical compliance challenge for the electric-utility industry, and many power plants face shutdowns if mercury emissions are not contained. The current most viable mercury capture technology, activated carbon injection, cannot possibly solve all existing technological and economic challenges. With stricter limits, mercury removal efficiency with activated carbons decreases exponentially, thus more and more activated carbon has to be transported to the site of operation and injected. Activated carbon injection costs are already very high, and generally range from $6,000-$50,000 per pound of Hg removed.
The deployment of a new, cost-effective Hg-capture technology is crucial to mitigate mercury associated human health risks, national healthcare costs, and to cost-effectively assist the electric-utility industry in capturing mercury. The researchers' Phase I work has produced remarkable results where they have demonstrated an innovative fly ash based sorbent (X-FA) capable of powerful mercury capture at a fraction of current costs. The principle of the new sorbent is an innovative coating technology that deposits a thin mercury oxidizing activator layer around the fly ash particles. Once in contact with mercury vapor, the activator coated powder chemically binds and captures mercury. Many advantages over existing technologies come with the new sorbent development, including an upfront material production on-site of the source of pollution. The researchers are currently conducting necessary final research to demonstrate the X-FA sorbent on an industrial scale (beta injection tests at multiple coal-fired boiler/power facilities). Upon completion of Phase II an immediate X-FA product commercialization is expected to occur.