Historically, some hazardous wastes were disposed of in regular
landfills. Hazardous wastes must often be stabilized and solidified in order to enter a landfill and must undergo different treatments in order to stabilize and dispose of them. Most flammable materials can be recycled into industrial fuel. Some materials with hazardous constituents can be recycled, such as lead acid batteries. Many landfills require countermeasures against groundwater contamination. For example, a barrier has to be installed along the foundation of the landfill to contain the hazardous substances that may remain in the disposed waste.
Recycling Some hazardous wastes can be recycled into new products. Examples may include
lead–acid batteries or
electronic circuit boards. When
heavy metals in these types of ashes go through the proper treatment, they could bind to other pollutants and convert them into easier-to-dispose solids, or they could be used as pavement filling. Such treatments reduce the level of threat of harmful chemicals, like
fly and
bottom ash, while also recycling the safe product.
Incineration Incinerators burn hazardous waste at high temperatures (1600–2500 °F, 870–1400 °C), greatly reducing its amount by decomposing it into
ash and gases. Incineration works with many types of hazardous waste, including
contaminated soil,
sludge, liquids, and gases. An incinerator can be built directly at a hazardous waste site, or more commonly, waste can be transported from a site to a permanent incineration facility. Reactions in the furnace can also form
hydrochloric acid gas and
sulfur dioxide. To avoid releasing hazardous gases and solid waste
suspended in those gases, modern incinerators are designed with systems to capture these emissions.
Landfill Hazardous waste may be sequestered in a hazardous waste landfill or permanent disposal facility. "In terms of hazardous waste, a landfill is defined as a disposal facility or part of a facility where hazardous waste is placed or on land and which is not a pile, a land treatment facility, a surface impoundment, an underground
injection well, a salt dome formation, a salt bed formation, an underground mine, a cave, or a corrective action management unit (40 CFR 260.10)."
Pyrolysis Some hazardous waste types may be eliminated using
pyrolysis in a high temperature not necessarily through electrical arc but starved of oxygen to avoid combustion. However, when electrical arc is used to generate the required ultra heat (in excess of 3000 °C) all materials (waste) introduced into the process will melt into a molten slag and this technology is termed Plasma not pyrolysis. Plasma technology produces inert materials and when cooled solidifies into rock like material. These treatment methods are very expensive but may be preferable to high temperature incineration in some circumstances such as in the destruction of concentrated organic waste types, including PCBs, pesticides and other
persistent organic pollutants. == In society ==