Manage Dental Amalgam Wastes

Dental Wastewater Must Be Pretreated

National and state tests indicate that dental wastewater contains as much as 100-2,000 parts per million (ppm) of mercury. This greatly exceeds the state regulatory dangerous waste limit of 0.2 ppm. Amalgam separators are required of dentists in the state of Washington, unless a dentist can prove that their discharge meets limits for mercury. An amalgam separator is designed to remove waste amalgam from the rinse water in the vacuum line before it discharges to the sewer. These separator systems are used to capture scrap amalgam which is too fine to be removed by a trap or a screen. An ISO 14011 certified amalgam separator can remove up to 99% of the mercury in dental wastewater, if maintained properly. The information below is intended to help dentists to maintain their amalgam separators.

Many of the available separators have been subjected to rigorous testing and have met ISO 11143 standards. Dentists should be sure to confirm that their amalgam separator meets these ISO 11143 standards at the time of installation.

Choosing an Amalgam Separator offers information on how to find an appropriate separator for your office. There are a number of separator manufacturers that offer a variety of models. Which separator to use depends on the amount of water discharged or the number of dental chairs operated at the dentist’s office.

Federal Pretreatment Regulation, 40 CFR part 403, requires that all non-domestic sources of wastewater which represent significant sources of loadings which could harm POTW water systems must obtain a permit and meet local limits. Dentists must generally install and maintain an amalgam separator to meet those limits.

Waste in Septic Systems

Wastewater from amalgam separators and x-ray development can present a problem for the proper operation of septic systems. Dental wastes should never be discharged to a septic system.

Chair-side Traps

Chair-side traps are either disposable or reusable. Disposable amalgam traps are preferable to reusable traps because it is difficult to effectively remove amalgam particles from the reusable trap without spilling them into the drain or garbage. Consider replacing size 40 mesh traps with size 100 mesh traps if your suction system can function adequately with the smaller mesh. These finer screens may be more effective at trapping amalgam particles, however, they may require cleaning and changing more often. Change or clean chair-side traps as often as necessary per the manufacturers directions. Use universal precautions when handling the chair-side trap.

Reusable chair-side traps:

Disposable chair-side amalgam traps:

Amalgam from Vacuum Pump Filters

(located by the central suction pump)

Recycling Contact and Non-contact Amalgam

Salvage and store all contact and non-contact scrap amalgam in separate, appropriately labeled, tightly closed containers. Recycle scrap amalgam through an amalgam recycler or hazardous waste hauler. Follow the requirements of your amalgam recycler for the storage, disinfection and shipping of scrap amalgam.

Handling Scrap Amalgam

When removing an existing amalgam, remove it in chunks so that it is more likely to be caught in the chair-side trap.

Waste Amalgam Capsules

After mixing, amalgam capsules may still contain small amounts of mercury. All capsule waste, including any defective capsules, should be placed in a marked container with other non-contact scrap amalgam and then be recycled. Be sure to check with your amalgam recycler to see if they will take capsules with your scrap amalgam.

Do not dispose of amalgam capsules in the garbage, the red biomedical bag or through incineration. The capsules are hazardous waste and must be properly recycled or disposed through a hazardous waste hauler. Some Washington counties may take amalgam wastes at their hazardous waste collection facility. Contact your county solid waste department to find out if they accept this type of waste. Some companies also take amalgam waste shipped via mail-away containers.

Manage Elemental Mercury

In the event that elemental mercury (also referred to as free, bulk, or raw mercury) is present in your dental office:

Replacing Mercury Contaminated Plumbing

After your office adopts its new mercury and amalgam management practices, it may be a good time to clean or replace sink traps. Mercury from past practices often settles at low points such as sink traps and sumps. The slow dissolution of the mercury in a sink trap or sump can release mercury into the wastewater for years after past disposal practices have been corrected.

Whenever plumbing parts are removed or cleaned, caution should be taken to avoid spilling the contents in case amalgam or mercury are present. Pour and brush out the sludge and handle it as you would handle contact amalgam. The plumbing parts can then be put back in place or recycled.

What should I do in the case of a mercury spill?

Mercury spill kits are available from a number of sources, including: companies that specialize in Occupational Safety and Health Administration (OSHA) compliance supplies and equipment; amalgam recyclers; and dental product suppliers. Before purchasing a kit, make sure it comes with complete instructions on how to perform a spill clean-up. Train several staff members in proper spill clean-up procedures.

The following steps should be followed in the event of a mercury spill:

Related information

Sampling for Mercury in Dental Waste

Federal Pretreatment Regulation, 40 CFR part 403, requires that all non-domestic sources of wastewater which represent significant sources of loadings which could harm POTW water systems must obtain a permit and meet local limits. Dentists must generally install and maintain an amalgam separator to meet those limits.

Amalgam Separators is a section on the Web site of the American Dental Association.

Fact Sheet - Mercury Use in Dental Amalgam from the Interstate Mercury Education and Reduction Clearinghouse (IMERC).

Mercury-Dental Topic Hub™ from the Pollution Prevention Resource Exchange offers pollution prevention resources to dental offices.