Wastes exist as gas, liquid, or solid. When gas or liquid, they are called emissions (or pollution) instead of waste. A waste is only a waste if considered as such. When saying "waste", most people think of a good with a negative value and without owner - a w:public bad. But one can also see waste as a resource as in industrial ecology. Waste_DTD ?
Nature wastes and human wastes
Waste produced by Nature are integrated in recycling processus. (Dry leaves in a forest are transformed in humus by microorganisms). Out of their natural environment, these wastes may become "real wastes" (dry leaves on the supermarket parking). However, the highest quantity of wastes come from human industrial activity, mining wastes, products transformation wastes, packaging. Any resource transformed in product becomes a waste after a certain time. The volume of wastes is roughly similar to the volume of resources used by humans.
Sustainable use require a system view of environment issues. Let's suppose one feels a craving for an apple, and say he has choice between apples coming from Germany, and some from New-Zealand, by boats. Which apple would require the most energy to be eaten ? Depends of the consumer : if he went by bicycle to the shop, the german apple required less energy. However, if he went buy the apple by car, it might be that the energy requirement of the car from home to the shop be higher than the energy required for the apple to travel from New Zealand to the shop. Not even couting CO2 emissions.
Solid wastes and emission wastes
When one consider that every product ends up being a waste, it might be a good idea to analyse matters entering a production cycle, rather than analysing wastes usually diluted, resulting of the process. For example, a consumer buying products containing heavy metals in small quantities will probably not detect these heavy metals in the resulting waste. An analysis of products entering the production system, and a guarantee from the provider might be a wiser approach to prevent the final pollution (example : a farmer receiving sewage sludge to landfill on some of his field for fertilizing; the sewage sludge analysis is more likely to reveal the pollution than the soil itself after a couple of years) (see also The Natural Step).
Solid wastes : to eliminate, to reuse, to avoid
A post-consumer waste is the waste produced by the end-user (the garbage one put outside in the trash can).
This is the waste people usually think of. But though the most visible, this is very small compare to the waste created in the process of mining and production. The ecological rucksack of industrial production is the total amount of waste related to a good in the course of its life cycle. For some metals, such as gold, the rucksack can be of a volume of 500 000 times the volume of metal extracted. For each gram of gold produced, 500 kg of mining waste are produced, containing other heavy metals which may pollute the atmosphere under their powdery form. These manufacturing wastes are by far the primary output of many industrial production systems. In the United States, 93% of natural resources extracted are never transformed in goods, 80% of goods sold are thrown after only one use, 99% of ressources in a good are "waste" 6 weeks after having been sold. There are very large potential gains in eco-efficiency, increasing the ratio of production unit per unit of natural resource, and decreasing ratio of waste generated as a by-product. But mining waste are often perceived as waste only in case of an ecological crisis or when they are undesirable emissions.
Industry is slowly moving toward better use of its wastes. industrial ecology for example is a method which consist of using the waste of a factory (matter or heat) as resources of another factory. (see the industrial district of kalundborg in Sweden). Most wastes issues are due to products rejected outside of manufactoring processus, or those for which industrials don't feel responsible for : disposable packaging, free goods for advertisement...Shifting from service leasing rather than goods selling might be a solution.
Waste production distribution by sector
- Industry and energy production: 60%
- Farming and livestock production: 25%
- Building: 10%
- Consumer waste: 5%
These figures are from Finland but should be quite similar in other industrialised, developed countries.