Waste Disposal

Waste Disposal

Although the term SOLID WASTE refers to a wide range of discarded materials (from kitchen scraps to mine tailings), the component known as refuse has the greatest potential for environmental contamination. Refuse comprises solid wastes consisting of household garbage and commercial rubbish produced, usually in equal parts, by the residents and merchants of a community. If simply left to decay, refuse can become a serious threat to community health, both as a direct source of human illnesses and as an attractant to disease-carrying organisms. Therefore, many Canadian communities collect refuse from its source and deliver it to a waste-disposal site.

Many smaller towns and villages cannot afford a refuse collection service or a proper waste-disposal site. Because small communities are prevalent in Canada, improperly operated dumps outnumber the better-operated facilities used by larger communities. In most provinces the garbage dump is regarded as unacceptable. As they are on fire most of the time, they are a fire hazard, threatening users of the site, nearby fields, forests and buildings, and resulting in considerable damage each year. Dumps are also an ideal feeding ground for rats and other disease-carrying animals, and attract dangerous mammals as well as flocks of birds, which may pose a hazard to nearby airfields.

Major Canadian cities now use an improved method of waste disposal called sanitary landfilling. At a sanitary landfill, refuse is spread in thin layers, on the ground or in a trench, by a mobile compaction vehicle. Then a layer of clean soil is spread and compacted over the layer of refuse. Hence a series of alternating layers (refuse, soil, refuse) is built up until the trench is filled or a mound created. As cities expand, landfill once on the outskirts is surrounded by housing developments and industrial parks. It may be reclaimed for other uses, such as parks or golf courses.

Incineration is the most common method of refuse treatment in Canada. Some incinerators must handle 200 or more truckloads of refuse daily; hence, units capable of continual operation are needed. Newer, "starved air" incinerators are so efficient that special air-pollution control devices are not required. Some incinerators are equipped with boilers that use heat from burning garbage to produce hot water or steam, which can be used to heat buildings or operate machinery.

Up to 50% of refuse is said to be reusable; thus RECYCLING may offer the greatest potential for reducing the growing volumes of waste. In recent years there has been a move to community recycling programs, so that by 1993 some 70% of Canadian municipalities had some sort of recycling program. Ontario and British Columbia had the highest proportion (over 95%) of their populations with access to recycling programs. Only 46% of the population in the Atlantic provinces had access to such programs.

See also HAZARDOUS WASTES.