Comment on “Recent trends in anthropogenic mercury emission in the northeast United States” by J. M. Sigler and X. Lee: Waste‐to‐energy's low mercury emissions

Abstract

Sigler and Lee [2006] improperly speculate that high mercury emission levels in the northeast might be attributable to an inability of municipal waste combustors (MWC) to meet federal air emission standards. Nothing could be further from the truth. Had the authors checked readily available emission data from the U.S. Environmental Protection Agency (EPA) or contacted the industry trade group, Integrated Waste Services Association (IWSA), which I represent, they would have proof that actual recorded mercury emissions levels from all municipal waste combustors in the country consistently test significantly lower than the new Clean Air standards require. In fact, the U.S. EPA recently acknowledged that the emissions controls installed by IWSA members and municipalities as a result of the 1995 Maximum Achievable Control Technologies (MACT) rules are highly effective in reducing emissions of all the Clean Air Act (CAA) section 129 pollutants emitted by large municipal waste combustor (MWC) units. Indeed, following implementation of MACT rules promulgated in 1995, the waste-to-energy facilities that are subject to this rule have been recognized and reported by the EPA (M. Horinko and J. Holmstead, EPA, personal communication to M. Zannes, 2003) as clean, reliable, renewable sources of energy that produce 2800 megawatts of electricity with less environmental impact than almost any other source of electricity.... [U]pgrading of the emissions control systems of large combustors to exceed the requirements of the Clean Air Act Section 129 standards is an impressive accomplishment. [2] Mercury emissions from municipal waste combustors have declined by more than 95% since 1990 as reported by the U.S. EPA on the basis of actual test data from all MWC facilities nationwide [U.S. Environmental Protection Agency, 2002]. Average actual emission levels for mercury are less than 10 μg per dry standard cubic meter (dscm) compared to a federal standard of 80 μg/dscm, or 85% removal efficiency. [3] Unlike other industries, there is unprecedented accuracy in mercury and all other emission data for municipal waste combustors. All MWC facilities are tested annually, and actual test data are provided to and compiled by the U.S. EPA. In addition to these test requirements each MWC unit that uses carbon as a mercury sorbent must continuously monitor the carbon feed rate as a surrogate for Hg control and continuously maintain the carbon feed rate at or above the feed rate established during annual testing. As a result, MWC emissions inventories are not speculative. The MWC industry is in a unique situation where it has an abundance of test and operating data to prove what it is accomplishing relative to controlling mercury emissions. [4] In addition to the spectacular reductions in mercury emissions, IWSA members have conducted mercury collection programs in the communities they serve and have recovered several tons of mercury before it could make its way to either a landfill or municipal waste combustor or be washed down the drain. No other industry has undertaken such proactive measures with regard to mercury. [5] We ask that Sigler and Lee [2006] correct the mistake made in the referenced article. The U.S. EPA Office of Air and Radiation in Research Triangle Park, North Carolina, will confirm the facts stated in this comment. The significant reductions in mercury from municipal waste combustors are not merely a perceived achievement as noted in the article. The reductions are real and ongoing. The waste-to-energy industry, and those that research its accomplishments, should be given due credit.