On December 15th, 2016 the US EPA ruling passed! Click here for a fact sheet on the effluent limitations guidelines and standards for dental offices.
Below are what M.A.R.S. feels to be important excerpts from the US EPA Regulation. Below each excerpt is a M.A.R.S. Point of View on the given section of the Regulation. For more extensive information on the new US EPA ruling, please click here.
US EPA Law Breakdown
Summary (Page 2)
Dental offices, which discharge mercury present in amalgam used for fillings, are the main source of mercury discharges to POTWs; most of this mercury is subsequently released to the environment.
This final rule requires dental offices to use amalgam separators and two best management practices recommended by the American Dental Association (ADA).
DATES (Page 3)
The compliance date, meaning the date that existing sources subject to the rule must comply with the standards in this rule is (July 14th, 2020).
MANAGEMENT (Page 5)
B. Dental Amalgam Wastewater Sources and Management
1. Amalgam Separators
2. Polishing to Remove Dissolved Mercury from Wastewater
3. Wastewater Retention Tanks
4. Best Management Practices
Papers are now being written that not only prove the existence of soluble mercury, but prove how much is being produced in the dental waste water flow.
EXECUTIVE SUMMARY (Page 9-14)
The purpose of this final rule is to set a uniform national standard that will greatly reduce the discharge of mercury-containing dental amalgam to municipal sewage treatment plants, known as POTWs. . . ., approximately 40 percent of the dentists subject to this rule already have installed amalgam separators. Dental offices are the main source of mercury discharges to POTWs.
EPA estimates that across the United States, 5.1 tons of mercury and an additional 5.3 tons of other metals found in waste dental amalgam are collectively discharged into POTWs annually.
Capturing mercury-laden waste where it is created prevents is from being released into the environment. This final rule controls mercury discharges to POTWs by establishing a performance standard for amalgam process wastewater based on the use of amalgam separator technology. The rule also required dental dischargers to adopt two BMPs, one which prohibits the discharge of waste (“or scrap”), and the other which prohibits the use of the line cleaners that may lead to the dissolution of solid mercury when cleaning chair-side traps and vacuum lines.
When EPA established categorical pretreatment requirements, it triggers additional oversight and reporting requirements in EPA’s General Pretreatment Regulations. The General Pretreatment Regulations specify that Control Authorities (which are often the state or POTW) are responsible for administering and enforcing pretreatment standards, including receiving and reviewing compliance reports.
In the Great Lakes region, the maximum allowable discharge of mercury is 1.3 parts per trillion.
There is no separator that can meet that standard which is why nationally the rumored discharge limit is expected to be 4,000 to 15,000 ppt or nanograms/liter (ng/L). Today’s most popular separator can discharge as much as 7.2 million ng/L. As seen in the attached chart, some doctors who do not place amalgam are discharging between 400,000 to 600,000 ng/L.
2. The POTWs will as previously stated, will be responsible for reviewing compliance reports. There are extremely efficient systems available at no charge, to teach compliance.
Background (Page 14-22)
A. Legal Framework1. Clean Water ActEPA promulgates national effluent limitations guidelines and standards of performance for major industrial categories for three classes of pollutants:(1) conventional pollutants (total suspended solids, oil and grease, biochemical oxygen demand, fecal coliform, and pH)(2) toxic pollutants (e.g.: toxic metals such as chromium, lead, mercury, nickel, and zinc)(3) non-conventional pollutants, which are those pollutants that are not categorized as conventional or toxic (e.g.: ammonia-N, formaldehyde, and phosphorus).
EPA established national pretreatment standards for those pollutants that may pass through, interfere with, or may otherwise be incompatible with POTW operations.
(1. Clean Water Act)
The three classes of pollutants are “extremely” important for dental practices, even practices that do not require amalgam separators.
This section refers to pH (conventional pollutants, toxic metals (mercury) and non-conventional pollutants like ammonia and phosphorus (found in some evacuation line cleaners). Although not said here, we will discover later that dental practices can now be classified as a more restrictive category of SIU or CIU if designated so by the control authority (POTW) refer to Page 6, Section 4.
Effluent Limitations Guidelines and Standards (Page 16-22)
a. Best Available Technology Economically Achievable (BAT)
BAT represents the second level of stringency for controlling direct discharge of toxic and non-conventional pollutants. In general, BAT-based effluent guidelines and new source performance standards represent the best available economically achievable performance of facilities in the industrial subcategory or category. Following the statutory language, EPA considers the technological availability and the economic achievability in determining what level of control represents BAT. CWA Section 301 (b)(2)(A). Other statutory factors that EPA considers in assessing BAT are the cost of achieving BAT effluent reductions, the age of equipment and facilities involved, the process employed, potential process changes, and non-water quality environmental impacts, including energy requirements and such other factors as the Administrator deems appropriate. CWA section 304 (b)(2)(B). The Agency retains considerable discretion in assigning the weight to be accorded these factors.
b. Best Available Demonstrated Control Technology (BADCT)/New Source Performance Standards (NSPS)
NSPS reflect effluent reductions that are achievable based on the best available demonstrated control technology (BADCT). Owners of new facilities have the opportunity to install the best and most efficient production processes and wastewater treatment technologies.
e. Best Management Practices (BMPs)
Section 304(e) of the CWA authorizes the Administrator to publish regulations, in addition to effluent limitations guidelines and standards for certain toxic and hazardous pollutants, “to control plant site runoff, spillage or leaks, sludge or waste disposal, and drainage from raw material storage which the Administrator determines are associated with or ancillary to the industrial manufacturing or treatment process . . . and may contribute significant amounts of such pollutants to navigable waters.” In addition, section 304(g), read in concert with section 501(a), authorizes EPA to prescribe as wide a range of pretreatment requirements as the Administrator deems appropriate in order to control and prevent the discharge into navigable waters, either directly or through POTWs, any pollutant which interferes with, passes through, or otherwise is incompatible with such treatment works.
Best Available Technology (BATs) and Best Management Practices (BMPs) will both refer to products or processes that will be able to improve the efficiency of the existing process or system. Amalgam scrubbers have not historically been used due to size and expense. Dental amalgam scrubbers are now available as a result of improved products and advanced technology. Scrubbers will be the next step in achieving the lower discharge rates that are expected from the control groups (POTW).
DESCRIPTION OF DENTAL INDUSTRY & DENTAL AMALGAM WASTEWATER SOURCES AND MANAGEMENT(Page 22-29)
A. Dental Industry
According to the 2012 Economic Census, there are 133,221 U.S. dental offices owned or operated by 125,275 dental firms. Polishing to Remove Dissolved Mercury from Wastewater (Page 28)
B. Dental Amalgam Wastewater Sources and Management
Dental amalgam consists of approximately 49 percent mercury by weight. Mercury is the only metal that is in its liquid phase at room temperature, and it bonds well with powered alloy. . . . The other half of dental amalgam is usually composed of 35 percent silver, 9 percent tin, 6 percent copper, 1 percent zinc and small amounts of indium and palladium (DCN DA00131).
Mercury from dental amalgam in wastewater is present in both the particulate and dissolved form.
Best Management Practices (Page 29)
In addition to technologies, EPA also identified best management practices currently used in this industry (and included in the ADA BMPs) to reduce dental amalgam discharges. In particular, EPA identified two BMPs to control dental amalgam discharges that would not be captured by an amalgam separator and/or polishing unit. Oxidizing line cleaners can solubilize bound mercury. If oxidizing cleaners are used to clean dental unit water lines, chair side traps, or vacuum lines that lead to an amalgam separator, the line cleaners may solubilize any mercury that the separator has captured, resulting in increased mercury discharges. One BMP ensure the efficiency of amalgam separators by prohibiting use of oxidizing line cleaners including but not limited to, bleach, chlorine, iodine and peroxide, that have a pH lower than 6 or greater than 8.
The selection of pH lower than 6 and greater than 8.5 is excellent because that is the range where pH causes less amalgam to be solubilized. As an example, line cleaners with a pH of 1 or 2 can generate approximately 750,000 ng/L of soluble mercury (see attached charts on “Soluble Mercury Released due to pH).
Bleach, chlorine and peroxide have been used in the past as line cleaners and sometimes for general cleaning (when diluted). With the implementation of these regulations, these products are no longer allowed. Line cleaners with a pH lower than 6 and/or higher than 8.5 are prohibited.
Performance Standard (Page 35)
The final rule allows dental offices to continue to operate existing amalgam separators for their lifetime or ten years (whichever comes first), as long as the dental discharger complies with the other rule requirements including the specified BMPs, operation and maintenance, reporting, and record keeping requirements. Once the separator needs to be replaced or the ten-year period has ended, dental offices will need to replace the amalgam separator with one that meets the requirements of the final rule. EPA does not want to penalize existing dental offices or institutional dental offices that have already installed amalgam separators voluntarily or to comply with state or local requirements. EPA recognizes that these offices may currently have amalgam separators in place that do not meet the ANSI ADA specification or the criteria of the ISO 11143 2008 standard. EPA did not want to establish a rule that would require dental offices with existing separators that still have a remaining useful life to be retrofitted with new separators, both because of the additional costs incurred by dental offices that adopted technology to reduce mercury discharges ahead of EPA’s requirements and because of the additional solid waste that would be generated by disposal of the existing separators.
In additional to installing one or more amalgam separators compliant with the ISO 11143 standard (or its equivalent) and implementing the required BMPs, the pretreatment standards specify certain operating and maintenance requirements for the amalgam separator. For example, the final rule requires a documented amalgam separator inspection to ensure the separator is performing properly. As explained in Section V, malfunctioning separators or separators that have reached their capacity are ineffective. Therefore, in order to ensure that mercury is not discharged from the facility, it is important that dentists know the operational status of their amalgam separator (see 40 CFR 441.40©). As such, the final rule requires the separator to be inspected per the manufacturer’s instructions.
– Required operation and maintenance requirements
– Reporting and record keeping
– Maximum 10 years or until it needs to be replacedWhat is not said is:Most POTWs are aware that the discharge standards are nationally lower than the best possible discharge from the separator.This clause does not negate the requirement for improved technology to reduce their discharge limits. This leaves the door open for the addition of low cost mercury scrubbers to the dental evacuation system.
Applicability to Dental Office That Do Not Place or Remove Dental Amalgam (Page 37)
In the final rule, dental dischargers that do not place dental amalgam, and do not remove dental amalgam except in limited emergency or unplanned, unanticipated circumstances are exempt from any further requirements as long as they certify such in their One-time Compliance Report to their Control Authority.
Control Authority Oversight/Reporting (Pages 41 – 42)
EPA proposed to amend selected parts of the General Pretreatment Regulations (40 CFR part 403) in order to simplify oversight requirements for the approximately 117,000 dental offices subject to the proposed rule. Specifically, EPA proposed to amend 40 CFR part 403 to create a new classification of categorical industrial users specifically tailed to pretreatment standards for dental offices, dental industrial user (DIU).
In response, EPA did not revise the General Pretreatment Standards to create the proposed DIU category and associated requirements. Rather, this rule establishes for the purposes of Part 441, that dental dischargers are not SIUs or CIUs as defined in 40 CFR part 403 unless designated as such by the Control Authority.
Environmental Assessment (Pages 71-72 & 75)
A. Environmental Impacts
The CWA regulations known as Standards for Use and Disposal of Sewage Sludge, 40 CFR part 503, control the land application, surface disposal, and incineration of sewage sludge generated by POTWs. Of the 11.2 billion dry pounds of sewage sludge generated annually, about 60 percent, or 6.7 billion pounds, are treated to produce bio solids for beneficial use as a soil amendment and applied to about 0.l percent of agricultural lands in the United States (DCN DA00257). Approximately 5,500 pounds per year of dental mercury are contained in land-applied bio solids.
Approximately 18 percent, or 2 billion pounds, of the sewage sludge generated annually by POTWs are surface disposed in sewage sludge mono-fills or municipal landfills. Approximately 1,700 pounds per year of dental mercury are contained in surface disposed sewage sludge.
The remaining 22 percent, or 2.5 billion pounds, of sewage sludge generated annually by POTWs is disposed of through incineration. Approximately 2,000 pounds per year of dental mercury are contained in incinerated sewage sludge.
The elemental form of mercury used in dentistry has low water solubility and is not readily absorbed when ingested by humans, fish, or wildlife. However, elemental mercury may be converted into highly toxic methylmercury in aquatic environments by certain forms of anaerobic sulfate-reducing bacteria. Methylmercury has high potential to become increasingly concentrated up through aquatic food chains as larger fish eat smaller fish. Fish commonly eaten by humans may have methylmercury levels 100,000 times that of ambient water. The neurological effects of consumption of methylmercury-contaminated fish are well documented. Developmental effects to fetuses, infants, children, and fish consumption by women of childbearing age are of special concern. XII. Non-Water Quality Environmental Impacts Associated with the Technology Basis of the Rule (Page 75)
B. Air Emissions
Unbound mercury is highly volatile and can easily evaporate into the atmosphere. An estimated 99.6 percent of dental mercury discharges are in solid bound form; i.e. elemental mercury bound to amalgam particles 9DCN DA00018). Because the majority of dental mercury is bound to solid particles, it likely will not volatize to the atmosphere. Therefore, EPA expects the final PSES and PSNS will not pose any increases in air pollution.
PRETREATMENT STANDARDS FOR EXISTING SOURCES (Pages 88 – 90)
2. Installation, operation, and maintenance of one or more amalgam removal device(s) other than an amalgam separator. The amalgam removal device must meet the following requirements:
(i) Removal efficiency of at least 95 percent of the mass of solids from all amalgam process wastewater. The removal efficiency must be calculated in grams recorded to three decimal places, on a dry weight basis.
(v) The device(s) must be inspected in accordance with the manufacturer’s operation manual to ensure proper operation and maintenance, including confirmation that amalgam process wastewater is following through the amalgam separating portion of the device(s).
(viii) (b) Implementation of the following best management practices (BMPs):
(1) Waste amalgam including, but not limited to, dental amalgam from chair-side traps, screens, vacuum pump filters, dental tools, cuspidors, or collection devices, must not be discharged to a POTW.
(2) Dental unit water lines, chair-side traps, and vacuum lines that discharge amalgam process wastewater to a POTW must not be cleaned with oxidizing or acidic cleaners, including but not limited to bleach, chlorine, iodine and peroxide that have a pH lower than 6 or greater than 8.
441.50 Reporting, and Record Keeping Requirements (Pages 92 – 93)
(ii) The One-Time Compliance Report for dental dischargers subject to the standards of this part must include:
A. The facility name, physical address, mailing address, and contact information.
B. Name(s) of the operator(s) and owner(s).
C. A description of the operation at the dental facility including: The total number of chairs, the total number of chairs at which dental amalgam may be present in the resulting wastewater, and a description of any existing amalgam separator(s) or equivalent device(s) currently operated to include, at a minimum, the make, model, year of installation.
D. Certification that the amalgam separator(s) or equivalent device is designed and will be operated and maintained to meet the requirements specified in 441.30 or 441.40.
E. Certification that the dental discharger is implementing BMPs specified in 441.30(b) or 441.40(b) and will continue to do so.
F. The name of the third-party service provider that maintains the amalgam separator(s) or equivalent device(s) operated at the dental office, if applicable. Otherwise, a brief description of the practices employed by the facility to ensure proper operation and maintenance in accordance with 441.30 or 441.40.