The number five is for polypropylene, a plastic used to make catsup bottles and yogurt cups. Polystyrene can be recycled into video cassettes, office equipment, toys, combs, insulation for homes and buildings, serving trays, and ice scrapers. The number seven is for various other forms of plastic, which can be recycled into such products as lumber, tool boxes, flower pots, and playground equipment. These number codes enable sorters to rapidly sort different types of plastics into recyclable groups. Another method of handling garbage is incineration.
Incineration means burning garbage.
If incineration is not done correctly it pollutes the air. It can cause the release of dioxin, an often toxic family of chlorinated chemicals created by the incomplete combustion of carbon compounds. However, if incinerators are build correctly and are properly filtered, this can be a good and safe way of disposing of waste, and the heat energy produced by incineration can be used to generate electricity.