Removal of Mercury from Dental Amalgam Waste Water

摘要

Public health concerns about bioaccumulation of mercury in lakes and streams have promoted an interest in recovery of mercury from dental amalgam waste. Dental amalgam (50% mercury by mass) is suspected to be a major contributor to mercury found in municipal water treatment facilities. Sanitation districts are requiring or considering requiring dental clinics to meet mercury discharge limits, with typical discharge standards from 50 to 0.2 parts-per-billion (ppb). Separation devices have been used (particularly in Europe) to remove the solid pieces of amalgam from clinic waste water. However, the soluble fraction of dental amalgam prevents these devices from meeting lower discharge limits. Dental wastewaler contains large and fine amalgam particles, dissolved mercury species, and dissolved and suspended organic materials. ADA Technologies, Inc. (Englewood, CO) is developing an integrated system, capable of recovering amalgam particles and dissolved mercury, while avoiding interference from the organic matter present in the waste. The system combines elements of ADA's mercury sorbent development research with conventional particle separations methods. This research, funded by the National Institutes of Health, and in cooperation with Dental Recycling North America (DRNA, New York, NY), is targeted at developing mercury recovery systems that can achieve sub-ppb level discharge limits for small dental offices and large clinies.