Waste Water Discharges
Sewage and other liquid wastes that are placed into sewer systems are referred to as“ discharges.” Federal, state and local regulations govern waste water discharges into public sewer systems. In addition to ordinary sewage, waste water discharges from dental offices may include chemicals or metals that are subject to regulation. Chemical waste water discharges may include such wastes as:
• straight alcohol
• ether
• peroxide
• solvents
• X-ray fixer solution
Metals contained in waste water discharges may include such wastes as silver from X-ray fixer solution, amalgam and metals from patient rinse waters.
Waste water discharges containing chemicals or metals are a concern for regulatory agencies because they may interfere with sewage treatment plant operations, or pass through the treatment plant and are deposited in waterways and soils. Metals are known to pass through sewage treatment plants, and sewage treatment plants have established limits of metals permissible in their effluent and sludge.
Local requirements vary. Contact your local sewage treatment plant( also referred to as a Publicly Owned Treatment Works, or POTW) to determine what materials may be poured down the drain. If the POTW has a pretreatment program, some potentially hazardous materials may be accepted by the POTW, but prior approval is always necessary.
Federal regulations regarding amalgam separators also prohibit the flushing of waste amalgam and oxidizing or acidic cleaners to be discharged into a POTW.
Dental offices that use a private sewage or septic system should not discharge waste waters containing potentially hazardous materials to their system. Discharge of such wastes to the environment may harm soils, groundwater and other bodies of water.
PDA Waste Management Guidelines 7