Particle versus mercury removal efficiency of amalgam separators

Abstract

Objective. The intent of this project was to evaluate the efficiency of three commercial amalgam separators based on mercury and particle removal. Methods. Dental wastewater samples were collected from a 54-chair dental clinic and a one chair private dental office. Atomic absorption spectrometry was used to measure mercury, and a laser diffractometer method to determine the particle size distributions. Results. The mercury removal efficiency of the three units ranged from 26.5 to 61.8% for the 54-chair clinic and from 80.8 to 94.7% for the one chair office. Following treatment, the particle size range of the effluent was 8.3–19.2 μm for the 54-chair office and 27.5–41.4 μm for the one-chair clinic. For particle samples based on the silver–copper and copper standards, the three amalgam separators had a particle removal efficiency ranging from 92.3 to 99.9%. The initial particle size distributions for these samples were all under 100 μm. Conclusions. The efficiency of the amalgam separators is influenced by the initial concentration of the dental wastewater, the physical setup of the discharge system before the dental wastewater reaches the separators, and the addition of chemicals to the dental wastewater. In addition, it is likely that assessment of efficiency based on particle removal by weight may not be as effective as removal based on concentration.