Elemental mercury is a heavy, silvery-white liquid metal, often referred to as quicksilver. This substance is a powerful neurotoxin that poses a significant health risk primarily through the inhalation of its invisible, odorless vapor. Common household sources of elemental mercury include older fever thermometers, barometers, antique gauges, and electrical switches found in thermostats. Handling this substance requires extreme caution, as the goal is to prevent any release of vapor before certified hazardous waste professionals can manage its permanent disposal. This guide outlines the necessary procedures for the temporary, safe storage of elemental mercury found in a residential or non-commercial setting.
Immediate Containment and Preparation
Securing elemental mercury begins with prioritizing personal safety and minimizing the potential for vapor exposure. Before any handling begins, establish a well-ventilated area by opening windows and doors to the outside. Wear appropriate personal protective equipment (PPE), which must include chemical-resistant gloves, such as nitrile or PVC, and safety goggles to protect the eyes from splashes.
If the mercury is in a broken device, carefully use stiff paper or a specialized mercury collection kit to gently scoop up the visible droplets. Avoid using a standard vacuum cleaner or broom, as these actions will aerosolize the mercury, dramatically increasing the concentration of toxic vapor in the air.
For bulk liquid mercury, such as a container of quicksilver, the safest approach is to place the entire container inside a thick, sealable plastic bag. If a small amount must be transferred, use an eyedropper or a plastic pipette to move the liquid one drop at a time, performing this task over a secondary containment tray. Immediately seal the container once the liquid mercury is secured.
Requirements for Safe Storage Containers
The container must be constructed from thick, non-reactive material, such as high-density polyethylene (HDPE) plastic or glass, and must possess a tight-fitting, leak-proof lid. Containers made from aluminum must be strictly avoided, as mercury readily forms an amalgam with aluminum, which can quickly corrode the container wall.
A crucial step in preparing the mercury for storage is to introduce a layer of liquid on top of the metal to suppress vapor pressure. Covering the liquid with water, mineral oil, or glycerin creates a physical barrier to minimize vapor release. The selected liquid should completely submerge the mercury, acting as a temporary seal to reduce the escape of hazardous fumes.
The container should never be filled to the brim; a maximum fill ratio of 80 percent is recommended to allow for thermal expansion of the contents. Once sealed and covered with the suppression liquid, the container must be clearly and visibly labeled. The label must include the words “HAZARDOUS WASTE: MERCURY” and the date the mercury was placed into the container.
Designated Storage Location Protocols
The storage area should be secured and inaccessible to children, pets, and unauthorized individuals, often requiring a locked cabinet or closet. The location must maintain a consistently cool, stable temperature, ideally well below typical room temperature, as a decrease in temperature exponentially reduces the rate of mercury vaporization.
A secondary containment vessel is mandatory for all temporary storage of liquid mercury. This typically involves placing the primary storage container inside a larger, leak-proof plastic tub or tray that is capable of holding 125% of the total volume of the primary container.
The storage area must also be separated from any incompatible materials that could react with the mercury or the container itself. Elemental mercury is reactive with certain substances, and the container should not be placed near strong acids or bases.
- Acetylene
- Ammonia
- Alkali metals
- Strong acids or bases
Transitioning from Storage to Certified Disposal
Safe, temporary storage is a precursor to the mandatory permanent disposal of the material by certified professionals. Elemental mercury is classified as a hazardous waste, meaning it cannot be legally or safely thrown into the regular trash or poured down a drain. Improper disposal risks releasing the substance into the municipal waste stream or water system, leading to widespread environmental contamination.
The next step is to identify and contact local Household Hazardous Waste (HHW) programs or municipal solid waste authorities. These agencies operate permanent collection facilities or host periodic collection events specifically for hazardous materials like mercury. State environmental agencies are also a resource for finding authorized commercial hazardous waste contractors who can handle the collection.
When transporting the container, place the secondary containment vessel in the trunk of a car or the bed of a truck to minimize exposure within the passenger compartment. Prior to transportation, you should confirm the facility’s acceptance policies and hours of operation, as many require pre-registration.