It is difficult to determine the amount of energy consumed or produced in waste disposal processes in broader ecological terms, where causal relations dissipate into complex networks of material and energy flow. For example, "cities do not follow all the strategies of ecosystem development. Biogeochemical paths become fairly straight relative to wild ecosystems, with very reduced recycling, resulting in large flows of waste and low total energy efficiencies. By contrast, in wild ecosystems, one population’s wastes are another population’s resources, and succession results in efficient exploitation of available resources. However, even modernized cities may still be in the earliest stages of a succession that may take centuries or millennia to complete.":720 How much energy is used in recycling also depends on the type of material being recycled and the process used to do so. Aluminium is generally agreed to use far less energy when recycled rather than being produced from scratch. The EPA states that "recycling aluminum cans, for example, saves 95 percent of the energy required to make the same amount of aluminum from its virgin source, bauxite." In 2009 more than half of all aluminium cans produced came from recycled aluminium.
The construction industry may recycle concrete and old road surface pavement, selling their waste materials for profit.
Many recycling bins are designed to be easily recognizable, and are marked with slogans promoting recycling on a blue or green background. Others are intentionally unobtrusive. Bins are sometimes different colors so that user may differentiate between the types of materials to be placed in them. While there is no universal standard, the color blue is commonly used to indicate a bin is for recycling in public settings.
In order to meet recyclers' needs while providing manufacturers a consistent, uniform system, a coding system is developed. The recycling code for plastics was introduced in 1988 by plastics industry through the Society of the Plastics Industry, Inc. Because municipal recycling programs traditionally have targeted packaging—primarily bottles and containers—the resin coding system offered a means of identifying the resin content of bottles and containers commonly found in the residential waste stream.
The smaller wheelie bins, for domestic or light commercial use, typically hold 120 to 360 litres (26 to 79 imp gal; 32 to 95 US gal), with 240 litres (53 imp gal; 63 US gal) being the most common. They have a hinged flap lid and two wheels on the bottom on the same side as the lid hinge. There is a bar behind the hinge on the top of the bin which is used to move it, or to hoist it up onto a garbage truck for emptying. Bac à déchets The 240 litre bin is usually considered to have the same capacity as three traditional waste containers. In the UK, "wheelie bins" for non-recyclable domestic waste are currently collected either weekly or once a fortnight, depending on the local Council's waste management policies.