High levels of mercury in sewer sludge- amalgam largest source

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Mercury in Sewage Sludge/ Biosolids South Seattle

The amount of mercury measured in sewage sludge in the Seattle South Treatment

Plant has been decreasing since 2000. The average concentration of mercury in

biosolids has reduced by 52% (from 2.5 ppm to 1.2 ppm) by a program working with

dentists to reduce inputs from dental mercury amalgam.

http://www.ecy.wa.gov/mercury/mercury_sewage_sludge_s_seattle.html

Mercury in Sewage Sludge/ Biosolids Spokane

Mercury levels in sewer sludge at the Spokane treatment plant have declined by

59% since a program working with dentists to reduce mercury from dental amalgam

was introduced. (2.2 ppm to 0.9 ppm)

http://www.ecy.wa.gov/mercury/mercury_sewage_sludge_spokane.html

Mercury in Sewage Sludge/ Biosolids West Point- Seattle

Mercury levels in this King County treatment plant hovered around 2.5 parts per

million (ppm) of mercury through the end of the last decade and declined to 1.4

(44% decrease) after an effort to reduce mercury in sewers from dental amalgam.

http://www.ecy.wa.gov/mercury/mercury_sewage_sludge_west_point.html

Year 2005PPM Hg

West Point1.4 (cities with reduction programs in mercury from dental offices)

South Plant1.3

Spokane1.1

Tacoma1.7

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LOTT2.7 (cities without reduction programs)

Burlington3.9 ppm

http://www.ecy.wa.gov/beyondwaste/pdf/BiosolidsTreatment.pdf Mercury Reductions

Resulting from

Installation of Amalgam Separators

Mercury is a pollutant that is found in water and aquatic organisms, but it

primarily originates from air and

solid waste sources. Therefore, reduction programs are usually aimed at these

sectors. However, one way to

directly reduce mercury in wastewater is installation of amalgam separators. As

such, the Northeast states have implemented voluntary and mandatory programs to

install amalgam separators in dentists’ offices in the

region. In August 2003, the NEG-ECP Mercury Task Force adopted a regional goal

that 50 percent of dental offices in the region would install amalgam separators

by the end of 2005. This goal has been exceeded and the Mercury Task Force now

has new goals of 75 percent separator installation by the end of 2007 and 95

percent by the end of 2010. In 2005, it was estimated that the New England

states had the following rates of amalgam separator installation: Connecticut

– 65 percent, Maine – 95 percent, Massachusetts – 74 percent, New

Hampshire – 95 percent, Rhode Island – 25 percent, and Vermont – 15

percent. All of the Northeast states now have legislation or regulations that

require installation of amalgam separators.

Prior to legislation, many of the states had voluntary programs to encourage

dentists to install separators. For example, Massachusetts began a voluntary

program in 2004 that allowed dentists who installed separators prior to

legislation becoming effective in 2006 to be exempt from future Massachusetts

DEP amalgam separator installation, operation, maintenance, and upgrade

regulations and related fees until either 2007 or 2010, depending on the date of

installation. This program resulted in approximately 75 percent of dentists

installing separators. The environmental effects of this can be seen in the

mercury concentrations in sewage sludge at the Massachusetts Water Resources

Authority (MWRA) wastewater treatment plant, which receives sewage from homes,

businesses, and industries in 43 greater Boston communities. Sludge mercury

concentrations were measured at the MWRA treatment plant between September 2004

and August 2006 and the results demonstrated a clear reduction in mercury

concentrations during this time period. The mercury concentration in the

plant’s sludge pellets in September 2004 was 3.8 mg/kg; by August 2006 it had

decreased to 1.2 mg/kg. It was during this time period that the majority of

amalgam separators now in operation were installed.

In addition to these documented results in Massachusetts, similar results have

been seen by the Western Lake Superior Sanitary District in Duluth, MN. Sludge

mercury concentrations were measured between January of 1995 and January of

2006. In 1995, when there were no amalgam separators installed, sludge

concentrations were over 2 parts per million (ppm). In January of 2006, when all

of the 57 dental practices in the district had installed separators, sludge

concentrations were less than 0.5 ppm (Tuominen 2006). Reductions in wastewater

mercury concentrations mean that less mercury is being released to water bodies

and therefore less mercury is accumulating in fish. Concentrations in

incinerated sludge will also be reduced, resulting in reduced mercury emissions

from sewage sludge incinerators. This will lead to reduced deposition of mercury

and therefore reduced mercury inputs to water bodies.

While the Massachusetts results provide evidence that amalgam separators reduce

mercury in wastewater, the Northeast states would like to more closely examine

mercury sludge concentrations in the entire region. The NEGECP Mercury Task

Force plans to collect data on mercury in sludge from all of the Northeast

states and examine the results prior to and following installation of amalgam

separators. It is expected that the results for the region will be similar to

what has been seen in Massachusetts. creases in Fish Mercury Concentrations

In addition to significant reductions in fish mercury concentrations resulting

from decreases in local emissions in Massachusetts (see NESCAUM’s report,

Tracking Progress in Reducing Mercury Air Emissions) , significant decreases in

fish mercury concentrations have been observed in some locations of New York

State. In a New York State Department of Environmental Conservation study,

current fish mercury levels were compared to past levels. In the majority of

locations, current mercury concentrations were significantly lower than they

were 10 to 20 years ago (Simonin 2006). These decreases have not yet been

explicitly linked to decreases in emissions from specific sources, but it is

highly likely that declines in mercury emissions resulting from regional mercury

reduction programs contributed to the decreases in fish tissue mercury

concentrations.

Outreach to Policymakers

In late 2004, NEIWPCC, NESCAUM, and NEWMOA collaborated on writing Mercury

Pollution in the

Northeast: A Guide for Policymakers. The purpose of this document was to inform

state and federal policymakers and their staff of the reasons to be concerned

about mercury, the status of the mercury issues in the Northeast,

and what needs to be done to address the mercury problem. The document contains

background information

about mercury, as well as sections on regional mercury control efforts, federal

mercury programs, and further

actions that need to be taken to control mercury. The document was sent to the

congressional delegation for the Northeast states, as well as the environmental

committees of the state legislatures of the Northeast states. Following the

mailing, an article on the document was published in Inside EPA’s Water Policy

Report, a publication that reaches a national audience.

http://www.newmoa.org/prevention/mercury/neiwpccmercurysuccessstory.pdf

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