September 28, 2009
Dealing With Mercury The Right Way
By Michael D. Shaw
The toxic properties of mercury have been well-known since the 18th century, when mercury-based ointments were used in the treatment of syphilis. As it was described: A night with Venus was followed by a lifetime with Mercury. Ironically, the very signs of mercury toxicity—excessive salivation and gingivitis—were tracked by physicians to indicate that their patients were complying with the treatment regimen.
The phrase “mad as a hatter,” refers to various neurological maladies suffered by workers in that trade, who would dip fur pelts into hot mercuric nitrate in rooms with little ventilation—a trade secret brought to Britain by the Huguenots, fleeing France after The Edict of Fontainebleau in 1685. In those days, if occupational hazards were even recognized, they were preferable to a quicker death by starvation.
It would be Minamata Disease, discovered in 1956, and based on acute mercury toxicity derived from methyl mercury effluents coming from Nippon Chisso Hiryo Company, that would engage the public’s interest, and help launch the modern environmental movement.
Mercury deposition in the environment has increased by about 300 percent since the dawn of industrialization—the bulk of the mercury coming from the burning of coal. Mercury released in this manner is in its elemental format, and is thus insoluble. However, as it enters the so-called global mercury cycle, it can become oxidized into the soluble Hg(II) form, which is then taken up by various microorganisms and is converted to methyl mercury. Some species of bacteria can even de-methylate the mercury.
Methyl mercury accumulates in aquatic organisms, which transfer mercury in the food chain. The higher up a species is in the food chain, the more methyl mercury is accumulated. Thus, fish from certain waters known to be polluted are removed from human consumption.
The mercury cycle is further complicated in that mercury can stay in the atmosphere for a long time, and migrate all over the world. This phenomenon would explain the apparent paradox whereby dam-created lakes in northern Canada—far removed from any source of mercury pollution (man-made or otherwise)—still produced mercury-laden fish, that would affect the local population.
On May 6, 2009, the EPA announced that it is proposing amendments to the current National Emission Standards for Hazardous Air Pollutants (NESHAP) for the portland cement manufacturing industry. Mercury (Hg) is one of the chemicals under review.
As one of the largest cement manufacturing facilities in the US, Lafarge’s Ravena, NY plant would be affected. The company had run voluntary comprehensive testing—at a cost in excess of $250,000—in 2008. The purpose of this testing was to…
- Determine the Hg content of raw materials and fuel
- Develop an understanding of the incorporation and removal mechanisms within the cement manufacturing procedures used
- Establish the Hg content of products and byproducts
- Verify the Hg content of the stack gas
Stack testing was performed by Air Control Techniques, P.C. of Cary, NC, and all protocols used were submitted to the New York State Department of Environmental Conservation (NYSDEC) for comment and approval. All analyses were conducted using Quality Assurance / Quality Control procedures established by the United States Environmental Protection Agency and the New York State Department of Health.
Here are some key findings of the study…
98.7 percent of the of the mercury emissions are elemental mercury. Inasmuch as the elemental form is less harmful on a local impact basis, this is far better than the typical (to cement plants) 75 percent. Only 10.4 percent of this mercury comes from the coal fly ash. Most of it derives from the process limestone.
NYSDEC provides 1-hour and annual average guideline concentrations called Short-Term Guideline Concentrations (SGCs) and Annual Guideline Concentrations (AGCs) for regulated compounds. The study showed that the Hg emissions impacts will be 0.11 percent of the AGC and 1.23 percent of the SGC. It is also noted that the plant’s stack gas Hg concentrations are lower than all of the international standards known to Lafarge.
These results were so good that they were highlighted during a January, 2009 presentation entitled “Mercury Emission Reductions,” given by Thomas Gentile of NYSDEC to the local school board, and interested members of the public.
More good news is that Lafarge intends to modernize the 47-year-old facility. This project will…
- Increase its fuel efficiency
- Improve its environmental performance
- Help protect good paying manufacturing jobs in Upstate New York
- Create hundreds of temporary jobs over a three-year construction period
- Pump much-needed revenue into the region’s economy
Lafarge is proud of its Ravena operation, and is always happy to discuss the issues and arrange plant tours, according to the facility’s environmental manager John Reagan. As Reagan observes, “Some people come here with low expectations, and they walk away with quite a different impression.”