Waste represents an enormous loss of resources both in the form of materials and energy. Indeed, quantities of waste can be seen as an indicator of the material efficiency of society. Waste generation is increasing in the European Union, and amounted to about 3.5 tonnes of solid waste per person in 1995 (excluding agricultural waste) 1
Excessive quantities of waste result from:
inefficient production processes
low durability of goods
unsustainable consumption patterns.
Solid waste is also increasingly produced as an attempt to solve other environmental problems such as water and air pollution. Some of these wastes give rise to new problems -examples include sewage sludge and residues from cleaning of flue gases.
Managing waste causes a number of pressures on the environment:
leaching of nutrients, heavy metals and other toxic compounds from landfills;
use of land for landfills;
emission of greenhouse gases from landfills and treatment of organic waste;
air pollution and toxic by-products from incinerators;
air and water pollution and secondary waste streams from recycling plants;
increased transport with heavy lorries.
An increasing part of resources contained in waste is recovered as materials or as energy in incinerators or biogas plants, but more than half is still permanently lost in landfills. Recycling of materials may reduce the environmental impact of waste but is not necessarily without environmental impact. For example, plants processing scrapped cars produce large amounts of shredder waste contaminated with oil and heavy metals and smelting of the metals give rise to emissions of heavy metals, dioxins etc. from secondary steel works and aluminium smelters.
Few resources can be retrieved completely from waste. In most cases recycled material will be of a somewhat lower quality than the virgin material due to contamination or the nature of the recycling material. Even high-quality recycled materials represent a net loss of resources because the energy used for initial production is lost and some material is always lost during collection and treatment.
The quantities of waste are now so large that transport of waste is a significant part of total transport. A French study indicates that about 15% of the total weight of freight transported in France in 1993 was waste and that waste transport accounts for 5% of the total transport sector energy consumption (Ripert, 1997). Rough estimates from Denmark indicate a lower but still significant energy consumption for transport of waste. The French study also shows that transport distances are much higher for waste for recycling than for disposal. This implies that efficient planning tools are needed to control transport resulting from separation of the waste into more and more fractions for advanced treatment - although higher transport distances for recycled materials may in some cases be compensated by reduced need for long-range transport of raw materials.