Glass
Main article: Glass recycling
Glass bottles and jars are gathered by a curbside collection truck and bottle banks, where the glass may be sorted into color categories. The collected glass cullet is taken to a glass recycling plant where it is monitored for purity and contaminants are removed. The cullet is crushed and added to a raw material mix in a melting furnace. It is then mechanically blown or molded into new jars or bottles. Glass cullet is also used in the construction industry for aggregate and glassphalt. Glassphalt is a road-laying material which comprises around 30% recycled glass. Glass can be recycled indefinitely as its structure does not deteriorate when reprocessed.
Paper
Main article: Paper recycling
Paper can be recycled by reducing it to pulp and combining it with pulp from newly harvested wood. As the recycling process causes the paper fibres to break down, each time paper is recycled its quality decreases. This means that either a higher percentage of new fibres must be added, or the paper downcycled into lower quality products. Any writing or colouration of the paper must first be removed by deinking, which also removes fillers, clays, and fibre fragments.[22]
Almost all paper can be recycled today, but some types are harder to recycle than others. Papers coated with plastic or aluminium foil, and papers that are waxed, pasted, or gummed are usually not recycled because the process is too expensive. Gift-wrap paper also cannot be recycled due to its already poor quality.[22]
Sometimes recyclers ask for the removal of the glossy inserts from newspapers because they are a different type of paper. Glossy inserts have a heavy clay coating that some paper mills cannot accept. Most of the clay is removed from the recycled pulp as sludge which must be disposed of. If the coated paper is 20% by weight clay, then each ton of glossy paper produces more than 200 kg of sludge and less than 800 kg of fibre.[22]
Plastic
Main article: Plastic recycling
Plastic recycling is the process of recovering scrap or waste plastics and reprocessing the material into useful products. Compared to glass or metallic materials, plastic poses unique challenges. Because of the massive number of types of plastic, they each carry a resin identification code, and must be sorted before they can be recycled. This can be costly; while metals can be sorted using electromagnets, no such 'easy sorting' capability exists for plastics. In addition to this, while labels do not need to be removed from bottles for recycling, lids are often made from a different kind of non-recyclable plastic.
To help in identifying the materials in various plastic items, resin identification code numbers 1-6 have been assigned to six common kinds of recyclable plastic resins, with the number 7 indicating any other kind of plastic, whether recyclable or not. Standardized symbols are available incorporating each of these resin codes.
