The creation and rapid growth of chemical industry during the past couple of decades established the need for hazardous waste management. Hazardous waste management encompasses two broad objectives: first, to develop and apply methods for proper use, treatment and disposal of materials, to prevent future site contamination, and second to identify and remediate waste sites contaminated by improper use, storage and disposal of hazardous materials in the past.
There are many ways of defining hazardous waste. The Resource Conservation and Recovery Act (RCRA) of the United States have defined hazardous waste as follows:
The term ‘hazardous waste’ means a solid waste or combination of solid wastes, which because of its quantity, concentration, or physical, chemical or infectious characteristics may:
(i) Cause, or significantly contribute to an increase in mortality, or an increase in serious, reversible, or incapacitating inevasible illness.
(ii) Pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of, or otherwise managed.
A working definition is as follows:
Hazardous wastes mean waste substances, typically in the form of solids, sludges, liquids or containerized gases, which by reason of their chemical activity or toxic, explosive, corrosive or other characteristics, cause danger or likely to cause danger to health or the environment.
Over the years, numerous attempts have been made by government, industry and public to define hazardous waste. Hazardous wastes are produced by diverse activities, ranging from industrial to domestic. Industries generate a wide variety of wastes, many of which can be considered toxic or hazardous due to the presence of components having toxic characteristics. Exposure to hazardous wastes could either have immediate toxic effects or result in toxic manifestations over a period of time. A major challenge facing environmental engineers is to develop methods for properly managing hazardous wastes, including minimizing generation, treating hazardous wastes that have been generated, and disposing off residues. The important functional components of hazardous waste management are as follows:
1. Identification of toxic and hazardous wastes
2. Sources and characteristics
3. Effects of toxic and hazardous wastes
4. Handling and transportation
5. Methods of disposal
6. Legislation etc.