In the twentieth century, humans have dealt with solid wastes in three basic ways: (1) by burning the waste, thus essentially injecting much of it, converted to gases and smoke, into the atmosphere (2) by storing wastes, including the leftover as from burning, in dumps, impoundments, and most recently sanitary landfills; and (3) by injecting or burying wastes in rock cavities deep underground (a method proposed for the disposal of industrial and conventional toxic or hazardous waste, as described below, and also for radioactive waste. Each of these waste disposal methodologies has its proponents and its critics. In the next few sections, we will consider each briefly.
Incineration
In the industrial technique of incineration, trash and garbage and burned in large furnace at high temperatures to get rid of much of the refuse as possible of course, burning trash is a time-honored procedure, but use of large incinerators dates back only to the late nineteenth century.
During their first 50 years of existence, incinerators were in and out of fashion. Many early incinerators were relatively inefficient caused massive pollution, and left large quantities of ash and other nondurables. But by World War II, some seven hundred new and improved incinerators were operating throughout the world.
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Some apartment buildings even had small incinerators to burn the residents’ trash. Nevertheless, incinerators continued to cause problems. Aesthetically, incinerators were an offensive intrusion on the skyline, and people who lived near them complained of the odors and said the smoke and gases caused respiratory problems.
The increasing environmental awareness of the late 1960s and early 1970s continued to erode people’s confidence in, and tolerance of, incinerators. The Air Quality Act of 1967 and Clean Air Act Amendments of 1970 established new emission standards that many existing incinerators did not meet; most operators simply closed their incinerators rather than adding costly emission control devices.
But shutting down the incinerators meant that the trash and garbage had to be disposed of some other way. The preferred alternative was sanitary landfills. But by the late 1970s and early 1980s, many cities and municipalities were finding that their landfills were running out of space, and there were fewer and fewer sites available, at least politically. An apparent solution to this predicament was presented by a new breed of incinerators known as resource recovery plants.
Mass-burn incinerators take a more direct approach to the waste. The unsorted trash and garbage is simply fed into a furnace that burns the refuse at very high temperatures 980 to 1100 C). The heat from the burning refuse is used to produce steam that drives a turbine to generate electricity. Whatever is not burned in the incinerator is removed and simple disposed of (for instance, in a landfill).