and community housing units burning their waste in small incinerators. But large-scale incineration in specially designed furnaces, with or without energy recovery, is of more-recent origin in the United States. The first U.S. waste-to-energy plant was operating in 1905 in New York City. Redesign of these systems for specialty use on municipal wastes led to today's generation of furnaces, most of which represent proprietary technologies from European manufacturers (IAWG 1995). According to the Integrated Waste Services Association (IWSA) in 1999, 103 waste-to-energy facilities in the United States combust about 15% of the nation's municipal solid waste (http://www.wte.org).
Hazardous waste is defined by EPA under the Resource Conservation and Recovery Act (RCRA) as a waste material that can be classified as potentially dangerous to human health or the environment on the basis of any of the following criteria:
It might ignite easily, posing a fire hazard.
It might be corrosive, capable of damaging materials or injuring people.
It might be reactive—likely to explode, catch fire, or give off dangerous gases when in contact with water or other materials.
It might be toxic, capable of causing illness or other health problems if handled incorrectly.
It might be on a list of specific wastes or discarded compounds that EPA has classified as hazardous.
Hazardous wastes are generated by entities such as manufacturers, service and wholesale-trade companies, universities, hospitals, government facilities, and households. They are generated both by the chemical manufacturing industry and by users. However, pollution-prevention programs are proliferating. Such programs are used in industry and are encouraged by federal agencies. They can be designed to study each manufacturing process with an eye to reducing hazardous materials used or generated, and thereby, reducing the amount of hazardous materials that could be released as air pollution, water pollution, or hazardous solid wastes. Such programs are used in industry and are encouraged by federal agencies. Not only can they reduce environmental effects at lower expense than do on-site emission control devices and water-treatment facilities, but they can save manufacturers money.
When a hazardous waste is generated, the generator can either manage the waste on site or move it off site for treatment, disposal, or recycling. Before the establishment of EPA and the enactment of stricter environmental laws and regulations in the 1970s, dumping of chemical wastes into inadequately designed landfills or simply onto the land or into rivers or oceans was common. Before