Professional Product Review — Vol. 7 | Issue 2 | 2012
Practical Issues for Purchasing, Installing and Maintaining Dental Amalgam Separators
A 2003 article published in the Journal of the American Dental Association (JADA) outlined a growing environmental concern over the accumulation of mercury in the tissue of some fish species. The concern prompted local, state and federal agencies to pursue stricter regulation of mercury released into public sewer systems. Although dental offices contribute a low overall percentage of mercury to the environment, they remain one of the most frequently referenced sources of mercury added to public sewer systems in the form of dental amalgam. Although mercury in dental amalgam is not immediately bioavailable—it has not been shown to contribute significantly to the problem of mercury in fish tissue— environmental agencies continue to develop regulations and/or outreach programs on a state and local basis encouraging, or in some areas, mandating, dental offices to install amalgam separators. The separators are intended to reduce amalgam discharges beyond those already achieved by chairside traps and vacuum filters. A dental office’s waste infrastructure and office procedures have been shown to significantly affect the choice of a suitable separator. Offices will also encounter important differences in operating and maintaining separator units properly. Anticipated federal requirements regarding separator installation will also be a key consideration for dental offices that do not currently have separators.
Overview. This article outlines key factors related to office infrastructure and operation that dentists should consider when investing in an amalgam separator. Since the initial article appeared, new local, state and federal regulations have been enacted or are under review, increasing the need for dental practitioners to understand the potential impacts of these requirements. The ADA amended its Best Management Practices to include amalgam separators in 2007. This article also provides a broad view of the recommended best practices to effectively manage and control potential amalgam discharges from all dental office activities, including cleanout and disposal of chairside traps and vacuum traps, cleaning of dental lines, and design or renovation of dental facilities.
Conclusions and Practical Implications. Before purchasing or installing an amalgam separator, consider factors specific to the available models, including size and maintenance requirements. Office-specific factors, such as plumbing configuration, available space for installation and subsequent access to that space for equipment replacement and maintenance, and building codes or lease stipulations may affect equipment choice and installation. Dentists should consider the effect an amalgam separator could have on existing suction equipment, as well as the short- and long-term costs, including maintenance and parts replacement. Dentists should also closely follow the development of potential new state and federal requirements that may include annual certifications, agency inspections and recycling, maintenance and recordkeeping requirements.
Placement and removal of dental amalgam restorations generates amalgam waste particles that can be suctioned into the dental unit vacuum line and some of the amalgam waste particles could be discharged into the public sewer system and eventually flow to the sewage treatment plant or publicly owned treatment plant (POTW). Chairside traps and vacuum pump filters generally remove up to 76 percent of the amalgam particles from the wastewater stream.1-3 However, some amalgam waste particles still enter the sewer system.
Amalgam separators are devices designed to increase removal of amalgam waste particles from dental office discharge. A variety of amalgam separators are currently available. Some of these units have been tested by the ADA 9, 11, and the most recent test results are summarized on page 2 of this issue of the ADA Professional Product Review. Amalgam particles in dental office wastewater can range in size from colloidal particles (smaller than 0.45 microns) to those larger than 3 millimeters.1,10 To capture these various sized particles from waste discharge, amalgam separator units typically use one or more of several separation techniques: sedimentation, filtration, centrifugation or ion exchange. Sedimentation-based separator units have baffles or tanks that reduce the speed of the wastewater flow, allowing amalgam particles, which are about 10 times heavier than water, to sink to the bottom of the unit. 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.
When selecting a separator for their offices, dentists should consider:
• utility requirements;
• dental office/building constraints;
• regulatory requirements;
• ease of maintenance and replacement;
• effect on suction equipment; and
• purchase, installation and maintenance costs.
To help summarize and simplify this process, a buyer’s checklist is included. (See Table 1. Amalgam Separator Buyer’s Checklist.)
Space Requirements. Amalgam separator sizing is a major consideration for selection and installation. Models may range in size from approximately 3 inches in diameter, occupying a 9-inch-square area, to 4 feet by 2 feet (1152 in2). The heights of units vary from 9 to 36 inches.
A separator’s performance relies, in part, on correct installation within the dental office’s existing wastewater and vacuum system. There are generally three distinct installation locations: 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 in-line between the dental operatories and the vacuum pump. An evaluation of amalgam separators installed in dental offices showed that amalgam waste particles were adequately collected in amalgam separators installed after the chair side trap or vacuum pump filter traps.9
Utility Requirements. Many separators rely on gravity or the vacuum system to operate and therefore do not require an electrical power source beyond that needed to power the vacuum system. However, some units do require electrical power connections for the control panel or to operate pumps that remove the settled effluent from the separator unit and discharge it to the sewer. Typically, these pumps are designed to operate at the end of the day or overnight, when the vacuum system is turned off.
Dental Office/Building Constraints
In addition to the size of the unit, a number of other factors can affect placement and installation of amalgam separators including:
• building configuration;
• available installation space;
• access to centralized plumbing lines; and
• office space leasing agreements.
Building configuration. Building configuration primarily refers to the existing plumbing set up in your office. For example, if the office is centrally plumbed, with all of the plumbing systems draining into one pipe, you may need to modify your 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 waste 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 the separator will be installed in the basement or in the office. Many dental offices install vacuum systems and air/water separators at the basement level to conserve office space. In that situation, separator installation is usually easier, as there is sufficient space upstream of the vacuum system to collect flow.
Installation can be more complicated in offices without basements. These offices often 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 chair-side amalgam separators in individual operatories.
Access to plumbing lines and amalgam separators. Dental office staff needs suitable access to inspect and maintain the separator. Dental practices that share plumbing or vacuum systems—as is often the case in multi-unit office buildings—will need to coordinate maintenance activities so as not to interfere with work schedules. Such coordination is particularly important if vacuum systems must be turned off for maintenance activities, or basement or closet access must be provided.
Offices in large, multi-story buildings also will likely face plumbing access issues as flows typically will be connected with larger building waste pipes that may or may not be easily accessed. Practices in such buildings may need to consider chair-side systems or systems that install upstream of the vacuum pump, depending on space availability.
Office-space leasing agreements. Many commercial lease agreements contain language that restricts the tenant’s ability to modify the building infrastructure. 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. More recently, some landlords, in response to local zoning requirements, have begun to require dental practices that lease space in a multitenant building to segregate and collect all dental wastewater discharges. It is unclear at this point whether such requirements eliminate the need for an installed amalgam separator.
Dentists who lease their offices as well as those who have space in a multi-unit building may wish to consult with their lawyer to determine liability should a pipe break or waste release occur at or near a separator they have installed.
Proposed Federal Standards
The U.S. Environmental Protection Agency has undertaken an initiative initiated a rulemaking process to mandate the installation of amalgam separators for all dental offices, subject to specific conditions. Exact details of the proposed rule are not available at the time of this printing, as the agency draft remains in final interagency review prior to release for comment by the general public. At this point, it is anticipated that the rule will be out for comment sometime in the next two years.
Disposal of Amalgam Waste
Many amalgam separator manufacturers offer recycling programs as a part of their service, which allows spent or full cartridges/separators to be shipped to recycling facilities. Offices should check with vendors to find out whether that service is available in their state and whether there are any storage requirements. It is also recommended that dental office waste procedures comply with ANSI/ADA Specification 109: “Procedures for Storing Dental Amalgam Waste and Requirements for Amalgam Waste Storage/ Shipment Containers.”16
As the waste generator, dental offices 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 (see “Ask Your Amalgam Recycler ” on Page 14.)
Plumbing code requirements. Dentists should investigate state and municipal plumbing code requirements before selecting and installing a separator system. In Massachusetts, for example, systems installed upstream of the vacuum system are classified as a part of the dental facility equipment and are exempt from facility plumbing code requirements. However, systems that are installed downstream of the vacuum system and discharge directly to the sewer system are subject to local plumbing requirements, and require permitting and installation by a licensed plumber. Most states and cities have different requirements, and offices should check with vendors and their local plumbing inspector to ensure that they meet local ordinance requirements.
Local wastewater treatment plant approved equipment lists. As noted earlier, some wastewater treatment facilities have 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 (such as chemical binding/ion exchange) may be necessary if the local utility or regulatory body has adopted very stringent mercury-reduction requirements.
Ease of Maintenance and Replacement
Maintenance of installed separators is an important and often overlooked component to ensure that the separator unit is operating as designed. It is critical to note that the installation of a separator is only the first step; it must be properly maintained, including regular changes in collection canisters or, depending upon the unit, switching out units in order to ensure that collection rates remain as designed. In general, a separator collection unit should be switched at a frequency of 6 to12 months; however, this can vary depending upon the volume of materials handled and number of operatories plumbed to the separator unit. A separator that is allowed to fill beyond its capacity result in complete bypass of amalgam particles from collection.
‘The maintenance requirements and schedules for amalgam separators vary widely and should be considered before buying. Smaller practices, with fewer support staff, for example, may choose to purchase a system that provides longer maintenance intervals and fewer inspection requirements.
Before purchasing a separator, there are several questions that should be posed to potential vendors. Ask about maintenance requirements and request copies of system manuals to compare features and manufacturers’ recommendations. Sales brochures may not provide sufficient details on maintenance requirements, making the operations and maintenance manuals 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.
Offices may want to ask vendors about the recommended treatment schedule and procedure to limit biological growth within the system. Some vendors recommend the use of a sterilant solution added chairside once per week to control such growth. Others recommend a daily treatment with non-foaming cleaning solutions. The amount of cleaner used and frequency of use will generally be determined by the length of the vacuum system lines and the amount of biological materials introduced into the system. Dentists should not use bleach or other corrosive solutions to clean out lines as they may remobilize bound mercury within the lines and reduce the effectiveness of separator units.23
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 office flows, as well as 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 or replacement.
Dentists should talk to the vendor about the potential effect the practice can anticipate should the separator break down. Ask questions that will help determine what type of post-installation servicing the vendor offers. Know the typical response time for removing or replacing a system in the event of clogging or failure, or whether canister or tank replacement needs to be performed by a vendor technician.
Ask how the amalgam separator unit indicates when a collection canister or cartridge is full and requires replacement. ISO standard 11143 specifies that units should provide “an auditory or visual sign, signal or other kind of indicator” that provides the user with information that maintenance/replacement is required. Operation of units beyond their capacity will often result in bypass and discharge of waste amalgam into the sewer system. These indicators may not always be obvious from a visual inspection of the unit.
Establish whether there are special material handling instructions or state or local amalgam waste handling regulations. Secure a list of recommended cleaners for use with the specific amalgam separator.
Effect on Suction Equipment
Dental offices need to understand how specific separator units may affect existing vacuum systems. Units placed 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 pre-set level of suction that is expressed in inches of mercury, and a typical unit is installed at a vacuum level of 7 to10 inches of mercury. After installing the separator, the installer should test the vacuum system performance under typical conditions, such as multiple operatories and associated evacuators in use as well as under closed conditions to ensure that suction has not been compromised. In general, a noticeable loss in vacuum 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 due to non-amalgam materials being carried in-line to the vacuum system filters. Offices that are centrally plumbed would have a system more prone to clogs due to the flow amalgam and non-amalgam wastes, such as prophy pastes and other solids, as would offices where the plumbing has long horizontal runs and/or numerous bends in the piping.
As noted earlier, these offices may need to re-plumb as part of the installation process. If plumbing reconfiguration is not an option, these practices could conduct more frequent inspection/maintenance of separator equipment to maintain sufficient vacuum pressures. Centrally plumbed offices also should look more closely at systems that are installed at the discharge side of air/water separators. These systems are designed to be drained 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 your own protection, you should get all warranty-related information in writing.
As with the purchase of any equipment, cost is clearly 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. A system is provided below that dentists can use to estimate the life-cycle cost of purchasing or leasing and maintaining an amalgam separator (See “Calculating Life-Cycle Cost”). Essentially, any approach used to compare the cost of separators should analyze upfront and ongoing expenses, including:
• purchase price;
• installation fee(s);
• ancillary parts included in cost (such as mounting plates, connection fittings;
• cost of replacement parts and accessories;
• cost of replacement tanks or cartridges, including shipping and other sometimes “hidden” fees; and
• office maintenance costs, labor.
The cost of replacement parts is often overlooked when buyers are evaluating cost Be sure to ask about these and 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. While the manufacturer can estimate these figures, you will need to consider factors specific to your own practice to more accurately predict the cost of a system.
In addition, keep in mind that some of your current maintenance costs, including labor, could change as a result of installing a separator. For example, if you install the separator ahead of the existing vacuum pump filters in your system, you may be able to slightly reduce the estimated maintenance cost for pump filter changes as fewer may be needed with this set up.
Finally, be sure to ask questions of the supplier to determine what other costs may apply. For example, if you are signing a contract that includes the purchase of a separator as well as the pickup or mail back of full collection canisters, are all shipping costs included in your contract fee. Some of these units when full can weigh 25 lbs. or more, requiring relatively higher shipping fees.
This article highlighted the changing technical environment facing dentists who generate amalgam waste and have not yet installed amalgam separators. There are important questions and considerations that dental offices should review before contacting vendors that will guide their discussions. 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. Dentists should pay close attention to the development of local, state and federal regulations regarding the installation of approved amalgam separators and for any additional changes for requirements concerning amalgam handling and best management practices for recycling.
Although this article was developed in cooperation with the ADA Council on Scientific Affairs and the Division of Science, the opinions expressed herein are those of the author and do not necessarily reflect the views and positions of the Council, the ADA Division of Science or the Association.
Mr. McManus has 26 years of environmental management and consulting experience within industry, public utilities and gov ernment agencies. As a former director of the Massachusetts Water Resources Authority’s industrial pretreatment program, he was responsible for compliance with EPA pretreatment regulations and federal/state permit conditions related to industrial wastewater permitting, health and safety, toxics management and emergency response.
He is a Senior P rogram Director at EBI, specializing in the implementation of environmental compliance and waste management programs for dental, health care, institutional and biotechnology facilities. Mr. McManus has provided training and technical support for the American Dental Association and numerous state dental societies on the topic of dental amalgam control and recycling, including the linkage between dental facilities and sewerage treatment plants, dental best management practices, and an ov erview of available amalgam collection/separation technologies and installation guidelines. He also manages dent al waste and safety training programs for Massachusetts, New Hampshire, Maine Dental Societies as their endorsed waste management provider. Mr. McManus holds BA and MA degrees in marine resource management and a M asters of Business Administration degree from Boston University.
Disclosure: Mr. McManus is Senior Program Director, EnviroBusiness, Inc., 21 B Street, Burlington, MA 01803, firstname.lastname@example.org.
1. Naleway CA, Ovsey V, Mihailova C, et al. Characteristics of amalgam in dental wastewater. J Dent Res 1994; 73 (IADR Abstracts):105.
2. Drummond JL, Cailas MD, Ovsey V, et al. Dental Waste Water: Quantification of constituent fractions. Academy of Dental Materials Transactions 1995;8 (Abstract P-22):112.
3. Adegbembo AO, Watson PA, Lugowski SJ. The weight of wastes generated by removal of dental amalgam restorations and the concentration of mercury in dental wastewater. J Can Dent Assoc 2002; 68(9):553-8.
4. U.S. Environmental Protection Agency, http://water.epa.gov/scitech/wastetech/guide/dental/index.cfm, Accessed 2/15/12
5. Technical Committee ISO/TC 106, Dentistry, Subcommittee SC 6, Dental Equipment. Dental equipment—amalgam separators. Ref. No. ISO 11143:1999(E). Interna¬tional Organization for Standardization. Geneva: ISO 1999.
6. Letzel H, de Boer FA, Van’t Hof MA. An estimation of the size distribution of amal¬gam particles in dental treatment waste. J Dent Res 1997;76:780-8.
7. Cailas MD, Ovsey VG, Mihailova C, et al. Physico-chemical properties of dental wastewater. WEFTEC ’94: 67th Annual Conference and Exposition. Chicago, Oct. 15-19, 1994. Alexandria, VA: Water Environment Federation, pp. 317-27, 1995.
8. Fan PL, Batchu H, Chou HN, et al. Laboratory evaluation of amalgam separators. J Am Dent Assoc 2002;133:577-89.
9. Metropolitan Council, Environmental Services; Minnesota Dental Society. Evaluation of Amalgam removal equipment and dental clinic loadings to the sanitary sewer. St. Paul, Minn.: MCES, MDS. December 2001.
10. American Dental Association. Best Management Practices for Amalgam Waste. 2003. http://www.ada.org/1540.aspx. Accessed July 31, 2012.
11. VanDeven, J, McGinnis, S. An Assessment of Mercury in the form of Amalgam in Dental Wastewater in the United States. Journal of Water, Air and Soil Pollution 2005;164:349-366
12. Personal Communication, Kerry Britt, Narragansett Bay Commission, February 2, 2012.
13. McManus K, co-authored with Wisconsin Dental Association, Amalgam Separator Decision Matrix, http://www.wda.org/media/07/377-decisionflowsheetmatrix.pdf. Accessed July 31, 2012.
14. McManus KR, Fan PL. Purchasing, installing and operating dental amalgam separa¬tors: practical issues. J Am Dent Assoc 2003;134:1054–1065 and American Dental Association Council on Scientific Affairs.
15. U.S. Environmental Protection Agency, Notice of Final 2010 Effluent Guidelines Program [EPA–HQ–OW–2008–0517; FRL–9483–4]; American Dental Association estimates in 2003 that dental facilities contribute up to 50% of mercury entering sewage treatment plants, Federal Register (Vol. 76, No. 207, October 26, 2011), p. 66301.
16. American National Standards Institute/American Dental Association ANSI/ADA Speci¬fication No. 109-2006. Procedures for storing dental amalgam waste and requirements for amalgam waste storage/shipment containers.
17. Batchu H, Chou H-N, Rakowski D, Fan, PL. The effect of disinfectants and line clean¬ers on the release of mercury from amalgam. J Am Dent Assoc 2006;137:1419.
18. Personal Communication, Kerry Britt, Narragansett Bay Commission Pretreatment Coordinator, February 15, 2012.
19. U.S. Environmental Protection Agency, Memorandum of Understanding on Reducing Dental Amalgam Discharges. http://water.epa.gov/scitech/wastetech/guide/dental/upload/2008_12_31_guide_dental_mou.pdf. Accessed July 31, 2012.
Calculating Life-Cycle Cost of Amalgam Separators
Life-cycle costing, as the name suggests, estimates the cost a piece of equipment will run from the time it is purchased until it is replaced. The following sample calculations are based on a life expectancy of five years. This calculation considers initial purchase price, cost of replacement parts, labor costs associated with maintenance and inspection, and so forth. The sample worksheets below illustrate both separator purchase scenarios in present-day U.S. dollar values.
Ask Your Amalgam Recycler*
What kind of amalgam waste do you accept? †
• Do your services include pick up of amalgam waste from dental offices? If not, can amalgam waste be shipped to you?
• Do you provide packaging for storage, pick up or shipping of amalgam waste?
• If packaging is not provided, how should the waste be packaged?
• What types of waste can be packaged together?
• Do you accept whole filters from the vacuum pump for recycling?
• Is disinfection required for amalgam waste?
• How much do your services cost?
• Do you pay for clean non-contact, “scrap,” amalgam?
• Do you accept extracted teeth with amalgam restorations?
• Does your company have an Environmental Protection Agency or applicable state license to recycle/reclaim this material?
• Does the company use the proper forms required by the EPA and state agencies?
• To whom do you sell recovered mercury and silver from my amalgam waste?
* Since the generator of the waste is responsible for proper disposal, dentists should get these replies in writing from their recycler.