the mercury ( hg ) content of dental - operatory wastewater has become an issue in many localities , and hg removal is rapidly becoming a matter of concern for all dental clinics . 
 this preliminary study tested the efficacy of polymers for the removal of hg contaminants from the dental - unit wastewater stream . 
 two commercially available polymers were used to treat dental - operatory wastewater . used separately , each polymer removed from 74.9% to 88.4% of the hg from dental - wastewater supernatant . 
 the polymers used in combination , within the recommended ph range , removed up to 99.9% of the total hg from dental - wastewater supernatant . 
 the estimated optimal concentration of the two polymers is approximately 2.33 ml of each per liter of waste , and more than 90% of the hg may be removed with 0.13 ml / l . 
 results indicate that a combination of the two polymers may sufficiently reduce hg levels to allow discharge of clarified supernatants into public sewer systems.imagesfigure 1figure 2figure 3figure 4figure 5figure 6figure 7