What is in toxic waste?
(Lansing State Journal, September 14, 1994)
When they are no longer useful, they are disposed of as waste. Toxic wastes may contain organic chemicals (e.g. phenol or TNT), inorganic chemicals (e.g. phosphates and sulfides), heavy metals (e.g. lead or mercury), or mixtures of both.
The term "toxic" indicates that there is some sort of poisonous substance in the waste. A more commonly used term is "hazardous waste". Different hazards are associated with different types of wastes. For example, most organic solvents such as ethanol can catch fire relatively easily. Commonly used acids and bases can cause severe burns when in contact with skin. Heavy metals, such as lead and mercury, are toxic to most living things at relatively dilute concentrations. These different hazards can be avoided with proper handling.
Hazardous wastes are separated according to their chemical contents. For example, organic solvents are separated from acids and bases. This separation helps in many ways. One can prevent explosions and noxious releases by not mixing certain chemicals together. It is also much easier to recycle hazardous chemicals if they are not mixed together.
Finally, if there is no other way to reuse a hazardous chemical, it has to be disposed of. Some chemicals are rendered harmless by incineration. Others have to be buried in secured landfills, as no way currently exists to recycle them.