Amalgam separators are devices designed to remove amalgam waste particles in dental office discharge. Although there is no national regulation requiring the installation of amalgam separators in U.S. dental offices, regional and local requirements exist in some areas. For example, dental offices in Seattle/King County, Wash., are required to either show that the office can limit the total mercury concentration in discharged wastewater to 0.2 parts per million or install an amalgam separator selected from among those recommended by the King County Department of Natural Resources and Parks Industrial Waste Program.⁴ Dental offices in Wichita, Kan., also must be equipped with devices to reduce the amount of amalgam being discharged into the public waste stream.⁵ In Minnesota and Washington state, the dental associations have encouraged offices to voluntarily install amalgam separators.^6,7

A variety of amalgam separators are available (Table 1). In some areas that require installation of amalgam separators, dentists must choose a separator from a list of models; in other localities with such regulations, dentists can select any model provided that it meets certain performance criteria—such as those established by the International Organization for Standardization, or ISO.⁸ If a practitioner decides to install a separator, he or she may wish to consult with the local wastewater treatment facility before purchasing one to determine whether there are any limitations regarding the model being considered.

	TYPES OF AMALGAM SEPARATORS

TOP ABSTRACT TYPES OF AMALGAM SEPARATORS SPACE AND UTILITY REQUIREMENTS DENTAL OFFICE/BUILDING... REGULATORY ISSUES EASE OF MAINTENANCE AND... EFFECT ON SUCTION EQUIPMENT COST CONCLUSION REFERENCES

 
Sedimentation-based separator units have baffles or tanks that reduce the speed of the wastewater flow, allowing amalgam particles to settle out of the waste. Filtration units also can remove amalgam particles, in addition to colloidal particles and dissolved mercury, depending on the types of filters used. Centrifuge-based separator units spin wastewater, relying on centrifugal force to draw the amalgam particles to the sides of the unit. Ion-exchange systems take advantage of the tendencies of certain chemicals to bind with dissolved mercury in the dental water stream, causing the minute amalgam particles to separate from the solution and rest at the bottom of the separator. Amalgam separators that use ion exchange are well-suited for use in municipalities that have specific concentration limits on mercury-containing discharge into the waste stream, because they can remove very small amalgam and cationic mercury particles more readily than can sedimentation models. Separators that use ion exchange also do not rely totally on physical settling of particles, which is better for an in-line system handling peak flows.

Many models use sedimentation, which collects amalgam particles that settle out from the wastewater. Because of the high specific gravity of amalgam, sedimentation removes a considerable amount of amalgam in wastewater. Simple sedimentation can remove about 90 percent of amalgam particles from a water sample in a matter of several hours.¹⁰ Some amalgam separators use sedimentation followed by filtration and ion exchange, with the aim of removing smaller amalgam particles not removed by sedimentation as well as dissolved mercury particles (for example, cationic mercury).

Designs are incorporated into some amalgam separators that allow for longer sedimentation time. Draining of the wastewater collected in the amalgam separator can be achieved by suction, electrical pumps or gravity drainage. A laboratory evaluation¹¹ of 12 commercially available amalgam separators that used various separation techniques documented more than 95 percent efficiency for amalgam removal, a performance level that exceeds the ISO’s requirement for this equipment.⁸

When selecting the correct separator for their offices, dentists should consider the following:

– space and utility requirements;

– dental office/building constraints;

– regulatory considerations;

– ease of maintenance and replacement;

– effect on other equipment;

– cost.

We discuss these issues in relation to the purchase, installation and operation of dental amalgam separators. To help summarize and simplify this process, we have provided a checklist (Box 1, "Amalgam Separator Buyer’s Checklist," page 1059) that dentists can use as they review systems. We recommend that this checklist be completed, and the key specifications be reviewed for different units being considered during the purchase process.

	SPACE AND UTILITY REQUIREMENTS

TOP ABSTRACT TYPES OF AMALGAM SEPARATORS SPACE AND UTILITY REQUIREMENTS DENTAL OFFICE/BUILDING... REGULATORY ISSUES EASE OF MAINTENANCE AND... EFFECT ON SUCTION EQUIPMENT COST CONCLUSION REFERENCES

Installation locations. The performance of amalgam separators relies, in part, on correct installation within the dental office’s existing wastewater and vacuum system. There are generally three distinct installation locations for units: directly within the vacuum system piping (or "in-line") at or near individual operatory chairs; in-line at a central location upstream of the vacuum pump; or at the outlet side of the air/water separator.

Most systems are designed to be installed inline between the dental operatories and the vacuum pump. An evaluation of amalgam separators installed in dental offices showed that amalgam waste particles were collected adequately in amalgam separators located in the system after the chairside trap or vacuum-pump filter traps.¹² The figure illustrates the typical recommended locations for installation of the various systems listed in Table 1.

View larger version (32K): [in this window] [in a new window]   Figure. Amalgam separator installation locations.

	DENTAL OFFICE/BUILDING CONSTRAINTS

TOP ABSTRACT TYPES OF AMALGAM SEPARATORS SPACE AND UTILITY REQUIREMENTS DENTAL OFFICE/BUILDING... REGULATORY ISSUES EASE OF MAINTENANCE AND... EFFECT ON SUCTION EQUIPMENT COST CONCLUSION REFERENCES

 
In addition to the size of the unit, a number of factors can affect placement and installation of amalgam separators, including the following:

– building configuration;

– available installation space;

– access to centralized plumbing lines;

– office space leasing agreements.

Building configuration. Building configuration primarily refers to the existing plumbing setup in the dental office. For example, if the office is centrally plumbed, with all of the plumbing systems draining into one pipe, the dentist may need to modify the plumbing so that only drainage from amalgam-generating sources runs through the separator. Additional water flows (for example, from cuspidors, sinks and operatories used exclusively for hygiene appointments) can adversely affect performance of separators. All sources that generate amalgam wastes should be identified and, when feasible, plumbed separately to the separator.

Installation space. Many dental offices face space limitations, particularly those that do not have access to a basement. Before investing in a separator, dentists should determine whether they will be installing the separator in the basement or inside the office. Many dental offices install vacuum systems and air/water separators at the basement level to conserve office space. In these cases, installation of a separator usually is easier, because there is sufficient space upstream of the vacuum system to collect flow. Systems that are gravity fed require sufficient collection space for the daily flow to be properly discharged into the drain without backing up.

Installation can be more complicated in offices without basements. Often, these offices install vacuum systems in utility closets or cabinets, which limits the available space upstream for the amalgam separator. In some cases, space limitations may require the use of chairside amalgam separators in individual operatories.

Access to plumbing lines. It is important to ensure that the dental office staff has suitable access to the separator to inspect and maintain it. Dental practices that share plumbing or vacuum systems—as is often the case in multiunit office buildings—will need to coordinate maintenance activities so that they do not interfere with work schedules. Such coordination is particularly important if vacuum systems must be turned off for maintenance activities, or if basement or closet access must be provided.

Offices in large, multistory buildings also will likely face plumbing access issues because flows typically will be connected with larger building risers that may or may not be easily accessed. Practices in such buildings may need to consider chairside systems or systems that install upstream of the vacuum pump, depending on space availability.

Office-space leasing agreements. Lease restrictions also can affect decisions regarding amalgam separator installation. Dentists who lease office space should review the terms of their lease to determine whether they can make any electrical or plumbing connections under the existing agreement. Many commercial lease agreements contain language that restricts the tenant’s ability to modify the building infrastructure.

In addition, dentists who lease their offices, as well as those who have space in a multiunit building, may wish to consult with their lawyer to minimize liability should a pipe break or waste release occur at or near a separator that they have installed.

	REGULATORY ISSUES

TOP ABSTRACT TYPES OF AMALGAM SEPARATORS SPACE AND UTILITY REQUIREMENTS DENTAL OFFICE/BUILDING... REGULATORY ISSUES EASE OF MAINTENANCE AND... EFFECT ON SUCTION EQUIPMENT COST CONCLUSION REFERENCES

 
Regulatory requirements associated with amalgam separators can vary widely depending on office location. While environmental or public health/safety permits typically are not required for installation of amalgam separators, dentists should be aware of the potential for other regulatory issues.

Waste disposal. Mercury and silver that might be present in amalgam wastes can be recovered through a distillation process and reused in new products. The ADA strongly recommends recycling as a best management practice for dental offices.¹³

Many amalgam separator manufacturers offer recycling programs as part of their service, which allows spent or full cartridges/separators to be shipped to recycling facilities for a service fee or as part of a lease. Offices should check with vendors to find out whether this service is available in their states and whether there are any storage requirements.

Dental offices should be aware that as the waste generator, they are responsible for ensuring proper disposal of amalgam waste—whether they have contracted with a vendor-sponsored program or have arranged for a recycler independently. Offices should ask for, and separator vendors or recyclers should be willing to provide, appropriate documentation to demonstrate that they are working with reputable waste handlers (Box 2, "Questions to Ask Your Amalgam Recycler").

View this table: [in this window] [in a new window]   BOX 2 QUESTIONS TO ASK YOUR AMALGAM RECYCLER.*

Local wastewater treatment plant approved equipment lists. As noted above, some wastewater treatment facilities maintain lists of "approved" amalgam separators and vendors. These lists may be issued as a regulatory requirement (for example, as an amendment to local sewer ordinances) or as guidance included in "best management practices" programs. Dental offices should check with local officials to determine whether any specific requirements exist in their area. Dental offices also should ask how often they need to renew approval or certification for installed units.

Separators that incorporate advanced treatment of amalgam-containing waste (for example, chemical binding/ion exchange) may be necessary if the local utility or regulatory body has adopted stringent mercury-reduction requirements.

	EASE OF MAINTENANCE AND REPLACEMENT

TOP ABSTRACT TYPES OF AMALGAM SEPARATORS SPACE AND UTILITY REQUIREMENTS DENTAL OFFICE/BUILDING... REGULATORY ISSUES EASE OF MAINTENANCE AND... EFFECT ON SUCTION EQUIPMENT COST CONCLUSION REFERENCES

 
The maintenance requirements and schedules for amalgam separators vary widely and should be considered before buying. Smaller practices, with fewer support staff members, may choose to purchase a system that provides longer maintenance intervals and fewer inspection requirements.

Operations and maintenance manuals. Before purchasing a separator, dentists should ask vendors about maintenance requirements and request copies of system manuals to compare features and manufacturers’ recommendations. Sales brochures may not provide sufficient details about maintenance requirements; as a result, the operations and maintenance manuals are an important resource for accurately determining maintenance needs. Vendors also should be willing to provide a reference list with contact information for similar dental offices that have installed their separator; direct experience in operating a system is valuable information for the prospective buyer.

Recommended treatment schedule. In particular, offices may want to ask vendors about the recommended treatment schedule and procedure to limit biological growth within the system, which can impair equipment performance. Some vendors recommend the use of a sterilant solution once per week (added chairside) to control such growth. Others recommend a daily treatment with nonfoaming cleaning solutions. The amount of cleaner used and frequency of use generally will be determined by the length of the vacuum system lines and the amount of biological materials introduced into the system. In any circumstance, dentists should not use bleach or other corrosive solutions to clean out lines, because they may remobilize bound mercury within the lines, which would be released into the waste stream and thereby reduce the effectiveness of separator units.

Table 1 (page 1056) provides a summary of the recommended maintenance and inspection intervals for various units. In general, the in-line systems require more frequent inspection and maintenance to prevent blockages. For example, some models require a series of initial inspections to calibrate the system to the amount of wastewater and associated solids (such as amalgam, tissue, cement debris, pastes) flowing through the separator. In addition, some units may require a daily check of the system thereafter to determine when the fluid in the unit needs to be decanted and the outlet tube height adjusted for proper operation. Other systems, however, require only annual maintenance.

In addition to clarifying the maintenance schedule, dentists should talk to the vendor about the potential effect on the practice should the separator break down. Dentists should ask questions that will help them determine what type of postinstallation servicing the vendor will offer. Dentists also might ask about the typical response time for removing or replacing a system in the event of clogging or failure. In addition, they may ask whether canister or tank replacement needs to be performed by a vendor technician.

As part of their efforts to obtain maintenance information, dentists should determine whether there are any special material handling instructions from the vendor or state or local amalgam waste handling regulations. In addition, dentists should request that the vendor supply a list of recommended cleaners for use with their specific amalgam separator.

	EFFECT ON SUCTION EQUIPMENT

TOP ABSTRACT TYPES OF AMALGAM SEPARATORS SPACE AND UTILITY REQUIREMENTS DENTAL OFFICE/BUILDING... REGULATORY ISSUES EASE OF MAINTENANCE AND... EFFECT ON SUCTION EQUIPMENT COST CONCLUSION REFERENCES

 
Dental offices need to understand how specific separator units may affect their existing vacuum systems.

Existing vacuum systems. Units installed upstream of vacuum systems must be carefully installed to prevent loss of suction. The most common reasons for reduced vacuum suction include improper fittings, excessive hose bends or angles, or long hose runs (4 to 6 feet, depending on the model) added to existing vacuum pump piping. Vacuum systems are designed to provide a preset level of suction (expressed in inches of mercury), and a typical unit is installed at a vacuum level of 7 to 10 inches of mercury.

After installing the separator, the installer should test the vacuum system performance under typical conditions (for example, multiple operatories and their associated evacuators in use), as well as under closed conditions (that is, when no evacuators are in use within the operatories) to ensure that suction has not been compromised. In general, a noticeable loss in vacuum power indicates a potential installation problem.

Clogs in the line also can degrade vacuum performance. Systems that are designed to be installed directly in the vacuum line potentially are prone to clogging because of nonamalgam materials being carried in-line to the vacuum system filters. Offices that are centrally plumbed have systems that are more prone to clogs owing to the flow of amalgam and nonamalgam wastes (such as prophy pastes, tooth or gum tissue, or cements), than are offices in which the plumbing has numerous bends in the piping.

As noted above, these offices may need to replumb as part of the installation process. If plumbing reconfiguration is not an option, these practices could conduct more frequent inspection and maintenance of separator equipment to maintain sufficient vacuum pressures (and should be sure to factor this increased labor into costs). Dentists in centrally plumbed offices also could look more closely at systems that are installed at the discharge side of air/water separators. These systems are designed to be drained and settled when the vacuum system is turned off.

Finally, dental offices should review the warranty information for their vacuum systems, and contact their vendors to determine whether installation of a separator within the vacuum system could void the equipment warranty. Some manufacturers may not honor warranties on their equipment if parts of the system are modified by third parties. For dentists’ own protection, they should obtain all warranty-related information in writing.

	COST

TOP ABSTRACT TYPES OF AMALGAM SEPARATORS SPACE AND UTILITY REQUIREMENTS DENTAL OFFICE/BUILDING... REGULATORY ISSUES EASE OF MAINTENANCE AND... EFFECT ON SUCTION EQUIPMENT COST CONCLUSION REFERENCES

 
As with the purchase of any equipment, cost clearly is a key issue when choosing an amalgam separator. True side-by-side comparisons of system costs are difficult because numerous pricing and leasing programs exist. For example, some vendors offer purchase plans for just the system, while others provide lease-based systems that include replacement of filter cartridges or ion-exchange cartridges and recycling of amalgam waste. We have developed a system that dentists can use to estimate the life-cycle cost of purchasing or leasing and maintaining an amalgam separator (Table 2). Essentially, any approach used to compare the cost of separators should analyze upfront and ongoing expenses, including the following:

– purchase price;

– installation fees;

– cost of replacement parts and accessories;

– cost of replacement tanks or cartridges;

– office maintenance costs (labor).

When evaluating costs, buyers often overlook the cost of replacement parts. Dentists should be sure to ask about these, as well as request an estimated replacement schedule. For many systems, replacement cartridges can be up to 20 to 25 percent of the initial unit price. In addition, one should recognize that the frequency of replacement and, therefore, the cost of parts and maintenance will depend, in part, on each practice’s patient load and the number of amalgam restorations that are placed or removed. Although the manufacturer can estimate these figures, dentists need to consider factors specific to their own practices to more accurately predict the cost of a system.

Practitioners should assign a cost to the hours that will be required to monitor and maintain the separator. For example, determine which staff member will be responsible for cleaning the trap and performing any maintenance of the unit, estimate the number of hours per week or month he or she will invest in maintenance and recycling activities, and multiply this number by the staff member’s hourly wage.

In addition, dentists need to keep in mind that some of the current maintenance costs (including labor) could change as a result of installing a separator. For example, if a separator is installed within the piping system ahead of the existing vacuum pump filters in the dental office’s system, practitioners may be able to slightly reduce the estimated maintenance cost of pump filter changes, because fewer may be needed with this setup.

	CONCLUSION

TOP ABSTRACT TYPES OF AMALGAM SEPARATORS SPACE AND UTILITY REQUIREMENTS DENTAL OFFICE/BUILDING... REGULATORY ISSUES EASE OF MAINTENANCE AND... EFFECT ON SUCTION EQUIPMENT COST CONCLUSION REFERENCES

 
This article has highlighted the questions that a dental office should review before contacting amalgam separator vendors, and that will guide discussions with them. The bottom line is that one size does not fit all, and office configurations and operations can significantly affect the selection and installation of an amalgam separator.