Industrial facilities potentially use a wide variety of mercury-containing products or chemicals. Compounds that contain less than one percent mercury do not have to list it as a component on the material safety data sheets. However, using chemicals containing even these low levels of mercury can cause problems at the wastewater treatment plant. You can find out if any of the chemicals you currently use contain mercury by contacting the supplier and requesting a response in writing.
When mercury is allowed to escape down a drain, it comes in contact with water and becomes a contaminant that must be removed by your local wastewater treatment plant. Once in the water, it can be difficult and costly to remove or reduce mercury to safe limits.
Where might mercury be found in an industrial setting?
Mercury may be found throughout your facility in products such as batteries; chemical compounds; cleaning agents; laboratory reagents, elemental mercury for science experiments; fluorescent lamps; specialty lamps; switches, relays and sensors; manometers; thermometers; flame sensors and gauges.
Mercury may also be found in sewer pipes. Mercury can settle at a low point such as a sump or trap and remain in the pipes of a facility for many years. Often, the slow dissolution of the mercury in a sump, trap or pipe is enough to cause exceedance of mercury limits in wastewater even after best management practices are implemented. Hot spots in a facility's piping may appear where laboratories or equipment maintenance areas were located. Whenever traps or sumps are moved or cleaned, the solid contents should be treated as a hazardous waste unless proven otherwise.
Mercury as a By-Product of Manufacturing Processes
Because mercury is present in many rocks and ores, several industrial processes release mercury:
- Carbon Black Production;
- Chlor-Alkali Production;
- Coke Production;
- Petroleum Refining;
- Lime manufacturing;
- Portland Cement Manufacturing;
- Phosphate-based Fertilizer Manufacturing;
- Primary Smelting and Refining of Nonferrous Metals and Copper, except Aluminum;
- Industrial boilers; and
- Mercury switch manufacturing.
What can industrial facilities do to help?
- Complete a mercury inventory of your facility by using the Mercury Assessment Checklist - POTW [DOC];
- Phase out mercury-containing products and equipment, when possible;
- Substitute mercury-free batteries for mercuric oxide (mercury-zinc) batteries;
- Use safe, non-mercury cleaners and degreasers in labs, housekeeping departments and maintenance areas;
- Replace mercury-containing thermostats and switches with mercury-free alternatives when remodeling or replacing old equipment;
- Purchase septic tank and sump pumps that contain magnetic dry reed switches, optic sensors or mechanical switches instead of mercury tilt switches;
- Examine use of other mercury-containing products in your facility, including generators, high intensity lamps and manometers; and consider switching to mercury-free alternatives; and
- Implement a mercury-free purchasing policy.