On June 14, 2017, EPA final ruling, 40 CFR 441 (Effluent Limitations Guidelines and Standards for the Dental Category), concerning standards and best practices for effluent dental water was published in the federal register. The ruling has mandated the use of an amalgam separator, established best management practices (BMPs) prohibiting the use of oxidizers in dental effluent water, and requires a one-time certification of compliance for those subject under it.
The ruling prohibits discharging amalgam waste into public water sewage and subsequently mandates the use of an amalgam separator. The ruling specifies that the separator must comply with the ISO standard 11143 and maintain 95% of solids to meet that standard. Since the dental industry alone is releasing about 5 tons of mercury-containing amalgam into the sewage systems, the EPA has included this requirement in the ruling for the betterment of the environment.
The waterline cleaner BMP forbids the use of oxidizing waterline cleaners in “dental unit water lines, chair side traps, or vacuum lines that lead to an amalgam separator. Oxidizing line cleaners have been shown to contribute to the solubilization of mercury into public works. The ruling goes into further detail stating oxidizing line cleaners, “including but not limited to, bleach, chlorine, iodine and peroxide, that have a pH lower than 6 or greater than 8,” must not be used to treat dental waterlines.
"For existing sources, a OneTime Compliance Report must be submitted to the Control Authority no later than October 12, 2020, or 90 days after a transfer of ownership. For new sources, a One-Time Compliance Report must be submitted to the Control Authority no later than 90 days following the introduction of wastewater into a POTW."
As defined in § 441.50, the compliance report will essentially enforce the Pretreatment Standards for Existing Sources (PSES) and the Pretreatment Standards for New Sources (PSNS).
The PSNS and PSES dictates the following:
- “Removal of all dental amalgam solids from all amalgam process waste water…” as described in § 441.30.
- Implementation of BMPs which include the prohibition of oxidizing line cleaners in dental unit waterlines that discharge into public works.
As part of the report, those subject under the ruling must certify they are “implementing BMPs specified in § 441.30(b) or § 441.40(b) and will continue to do so.”
"The final rule is effective on July 14, 2017. The compliance date, meaning the date that existing sources subject to the rule must comply with the standards in this rule is July 14, 2020. After the effective date of the rule, new sources subject to this rule must comply immediately with the standards in this rule."
The EPA ruling published to the federal register can be found in full here:
WHY YOU SHOULD NOT USE OXIDIZING LINE CLEANERS
Sterisil Straw V2 - EPA Compliant waterline disinfectant for 365 days
The Role of the Amalgam Separator
Since Mercury is present in the dental waterline in both solid and dissolved form, the use of an amalgam separator accounts for 99.95% of the removal process. Most amalgam separators focus on removing solids but there is a recent push to develop separators with ion exchange capabilities to capture dissolved mercury.
Restrictions on Oxidizing Line Cleaners
One-time Compliance Report
Under the ruling, an existing practice will have until July 14, 2020 to install an amalgam separator, comply with the pretreatment BMP's, and submit their one-time compliance report. Newly constructed offices and offices that transfer ownership will have 90 days from the introduction of waste water into the public water supply.
At the time of publication, there are 12 states and 18 municipalities that already have programs in place to prevent mercury discharge. This final ruling will take precedence over any existing local code or requirements while preserving any addition requirements beyond the scope of the EPA ruling.