recycling

RECYCLING. Recycling is an ancient practice with many modern applications. It refers to the recovery and reuse of materials from spent products. In recent years recycling has become a major part of environmental policy, mainly because of the increased costs of solid- and hazardous-waste disposal, the scarcity of natural resources, and the growing concern over polluted land, water, and air. There are two types of recycling operations: internal and external. Internal recycling is the reuse …

…landfills reach their capacity, many municipalities turn to recycling programs as a relatively inexpensive alternative to landfill disposal. Some cities also solve energy-shortage problems and the need to dispose of growing amounts of organic wastes and garbage by converting waste into energy. This is done by pyrolysis, the incineration of refuse with a deficiency of air. While pyrolysis permits recovery of certain fuel gases, chemicals, and heat energy, it can also contribute to air pollution.