Wikipedia defines a hazardous waste is waste that poses substantial or potential threats to public health or the environment. In the United States, the treatment, storage and disposal of hazardous waste is regulated under the Resource Conservation and Recovery Act (RCRA).Hazardous wastes are defined under RCRA in 40 CFR 261 where they are divided into two major categories: characteristic wastes and listed wastes.[1]
- Characteristic hazardous wastes are materials that are known or tested to exhibit one or more of the following four hazardous traits:
- ignitability (i.e., flammable)
- reactivity
- corrosivity
- toxicity
- Listed hazardous waste are materials specifically listed by regulatory authorities as a hazardous waste which are from non-specific sources, specific sources, or discarded chemical products [2].
These wastes may be found in different physical states such as gaseous, liquids, or solids. A hazardous waste 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, The United Nations Environmental Programme(UNEP) estimated that more than 400 million tons of hazardous wastes are produced universally each year, mostly by industrialized countries (schmit, 1999). About 1- percent of this total is shipped across international boundaries, with the majority of the transfers occurring between countries in the Organization for the Economic Cooperation and Development(OECD) (Krueger, 1999).[3] Some of the reasons for industrialized countries to ship the hazardous waste to industrializing countries for disposal are the rising cost of disposing hazardous waste in the home country.[3
According to the Environmental Protection Agency (EPA), a chemical waste is considered to be hazardous if the waste exhibits any of the following characteristics.
Ignitability
A substance is considered to be ignitable if it
exhibits any of the following properties:
1. It is a liquid, other than an aqueous solution
containing less than 24% alcohol by volume and
has a flash point less than 60°C (140°F), as
determined by the Pensky-Martens Closed Cup
Tester.
2. It is not a liquid and is capable, under
standard temperature and pressure, of causing
fire through friction, absorption of moisture
or spontaneous chemical changes and, when
ignited, burns so vigorously and persistently
that it creates a hazard.
3. It is a flammable compressed gas
4. It is an oxidizer such as chlorates,
permanganates, inorganic peroxides, or nitrates
that yield oxygen readily to stimulate the
combustion of organic matter.
Corrosivity
A substance is considered to be corrosive if it
exhibits any of the following properties:
1. It is aqueous and has a pH less than or equal
to 2 or greater than or equal to 12.5, as
determined by a pH meter using either an EPA or
equivalent test method.
2. It is a liquid and corrodes steel (SAE 1020) at
a rate greater than 6.35 mm/year at 55°C.Created by
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