Mercury has a long and colorful history. Due to its curious nature as a liquid metal at room temperature, hence dubbed “quicksilver,” mercury has been intensely studied and used by alchemists, scientists, and religious leaders for thousands of years, and embraced by manufacturers since the Industrial Revolution. However, because of its toxic nature, and the difficulty to remove it from the environment, the use of mercury for common applications has been phased out greatly in recent years.
The United States Environmental Protection Agency (EPA) and Wisconsin Department of Natural Resources (WDNR) have been working with organizations to reduce the discharge of mercury to our public waters, air, and soils. As a part of this effort, the Waupaca Wastewater Treatment Plant is required to implement a Mercury Pollution Minimization Program to reduce mercury discharges to a concentration of less than 1.3 nanograms per liter (ng/L). This web page has been designed to educate businesses and individuals about mercury in our community.
Mercury is one of the few metals that will be in a liquid state at common temperatures. Because of this feature alone, mercury has served a role in low-tech position switches since the advent of electricity. It also has served a role in many anti-microbial agents, dental fillings, and lighting applications. The University of Wisconsin System is an excellent resource explaining the hazards of mercury. Information from the UW System can be found here: https://www.wisconsin.edu/ehs/hazmat/mercury/
Fortunately, mercury in elemental form is fairly insoluble in water. Once it is converted to methylmercury by certain bacteria, however, it becomes extremely difficult to remove from the environment. The main concern is that mercury is a bio-accumulator within wildlife, meaning that it cannot be easily expelled from an animal, and each successive predator will contain more and more mercury. This is why the WDNR has fish consumption advisories, especially concerning predator type fish such as walleye and northern pike.
About the Law
The EPA has determined that in order to protect wildlife from adverse effects, a discharge concentration limit of 1.3 ng/l (nanograms per liter) shall be required for states that could ultimately discharge to one of the Great Lakes. As perspective, a nanogram per liter is the equivalent of one part per trillion, or about 5.9 inches out of the entire distance from the earth to the sun.
What We Do
The primary function of a wastewater treatment plant, such as ours in Waupaca, is to remove organic matter and certain nutrients that cause water quality issues. Many compounds such as pharmaceuticals, toxins, and heavy metals such as mercury are essentially unaffected by conventional treatment. The costs for the equipment, energy, and technology which could treat such things would rival that of our entire current facility. Therefore, we depend on our neighbors and businesses to keep harmful things out of our treatment plant in the first place.
Waupaca WWTF Historical Influent Mercury Concentrations Annual Averages
The City of Waupaca Wastewater Treatment Plant has been tracking treatment removal efficiencies of mercury since 2013. The removal efficiency of mercury at the wastewater treatment plant is in the range of 92-95%. Mercury removal efficiency was a leading factor in the City changing the allowable mercury concentrations to be discharged to City sewers within our sewer ordinance. Prior to 2020, the mercury concentration discharge limit was 2000 nanograms per liter (ng/L). The updated ordinance now has a mercury concentration discharge limit set at a maximum of 15 nanograms/liter (ng/L). In order for the wastewater treatment plant to consistently meet the EPA mercury discharge limit of 1.3 nanograms per liter (ng/L), the incoming raw sewage concentration of mercury would have to be reduced to 15 ng/L or less.
Fortunately, the recent efforts to reduce mercury discharge in our city have shown great progress. The mercury concentration of the wastewater entering our plant has dropped from an average of 383 ng/l (for the years 2013 to 2017) to 56.7 ng/l (for the years 2017 to 2022). This has in turn reduced our mercury discharge concentrations after treatment by 20.5% over the same periods.
What Companies have done
Businesses and industry have been pressed to reduce mercury in both their processes and their products. Fortunately, advances in technology have made it cost effective to have mercury-free solutions for most applications where mercury has been recently used.
- Electronic pressure switches have replaced mercury position switches
- Mercury free low energy light bulbs (such as LED)
- Composite dental fillings
- Alcohol and digital thermometers
- Non-mercuric preservatives for medicines
- Digital thermostats
Companies have not only been cooperative in reducing the amount of mercury used in consumer products, they have also been successfully phasing out the use of mercury in their own establishments. This two-prong approach of providing mercury-free alternatives and eliminating older mercury containing technology has greatly reduced the amount of mercury at risk of being released to the environment.
One of the largest sources of mercury in wastewater has been dentistry offices, due primarily to the use of mercury amalgam (silver) fillings. In addition to having more mercury-free choices, the use of amalgam separators results in a capture of over 95% of mercury discharged by dentist offices. More information from the EPA on dental amalgam can be found here: https://www.epa.gov/mercury/mercury-dental-amalgam
Amalgam Application and Reporting:
Mandatory one time reporting for all installed separators.
Amalgam Separator Installation Notice Form
Each dental office shall maintain annual reporting and provide a copy to the City of Waupaca. Changes were made to the City of Waupaca Sewer User Ordinance Chapter 13.02 in Fall 2020. Dental offices are now required to recycle amalgam separator cartridges every 6 months. Notification to the City is required within 30 days of recycling an amalgam separator cartridge, and a proof of recycling certificate must be provided.
What Individuals can do
As individuals, there are three main things that can be done to help reduce discharges of mercury to the environment.
First and foremost is to educate yourself and other on the dangers of mercury and to realize that your actions can make a difference. In the event of a spill or break of a mercury-containing product, immediately follow the instructions found here: http://dnr.wi.gov/topic/spills/mercury.html
Secondly, make sure that you use mercury-free alternatives whenever possible.
Finally, remove from use and properly recycle mercury-containing products as you can.
The Waupaca County Processing and Transfer Facility accepts mercury-containing items for a very low fee. Additional information can be found here: https://www.waupacacounty-wi.gov/departments/solid_waste_and_recycling/hazardous_waste.php
Thermostats containing mercury may be disposed of at Woolsey Plumbing free of charge. Mercury thermostats are then recycled. Contact information for Woolsey Plumbing may be found on their website: https://www.woolseyplumbing.com/ or by calling 715-258-8237.
As a service to the residents of the City to make it easier to dispose of mercury containing items, the City of Waupaca will sponsor an ongoing mercury take-back program to accept the following items free of charge for proper recycling:
Mercury containing items may be dropped off at the front desk located inside City Hall at 111 S. Main Street, Waupaca, WI 54981. Call 715-258-4424 with any questions.
With the cooperation of mercury conscious individuals and businesses, we can greatly reduce our discharge of this harmful substance, and keep our waters and environment safe for the generations ahead of us.