HW is waste that poses substantial or potential threats to public health or the environment. It also is a waste product that no longer serves a useful purpose or must be disposed of in some fashion. In the United States, the treatment, storage, and disposal of HW are regulated under RCRA. HWs are defined under RCRA in 40 CFR 261, where they are divided into two major categories: characteristic wastes and listed wastes.
- • Characteristic HWs are materials that are known or tested to exhibit one or more of the following four hazardous traits:
- • Ignitability
- • Reactivity
- • Corrosivity
- • Toxicity
- • Listed HWs are materials specifically listed by regulatory authorities as HWs that are from nonspecific sources, specific sources, or discarded chemical products.
The requirements of RCRA apply to all the companies that generate HW as well as those companies that store or dispose of HW in the United States. Many types of businesses generate HW.
These wastes may be found in different physical states such as gaseous, liquid, or solid. An HW is a special type of waste because it cannot be disposed of by common means like other by-products of our everyday lives. Depending on the physical state of the waste, treatment and solidification processes might be required.
Worldwide, it has been estimated that more than 400 million tons of HWs are produced each year, mostly by industrialized countries.