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Ninety-five percent of King County dental offices have taken steps to reduce the amounts of mercury and silver discharged to the sewer system.

Most offices have installed amalgam separators and followed the required Best Management Practices (BMPs) for amalgam wastes and spent fixer. Partially as a result of these activities, mercury levels in King County Loop biosolids have dropped by 50 percent. The following graph illustrates the reduction in mercury in the county's Loop biosolids:


King County Loop Biosolids trucks

The condition of our Loop biosolids is the best indicator of the quality of King County wastewater discharges. King County's Loop biosolids contain only very small amounts of metals and organic chemicals, thanks to the cooperation of King County businesses and industry.

After processing and treatment, the County's Loop biosolids are beneficially recycled used as soil conditioners on farms, forests, lawns and gardens. Efforts to remove mercury from wastewater are ways to keep Loop biosolids clean and safe for recycling.

To help sustain this success, KCIW is continuing to inspect a portion of the dental offices each year to monitor how the offices are putting the required best management practices into effect. The program will continue to track mercury levels in the County's Loop biosolids.

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