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Landfill sites are awash with plastic bottles which could be recycled if only
it were cost-effective to sort them. Crown Cork and Seal of Illinois is
patenting a system which automatically sorts bottles made from different kinds
of plastics, and those that have contained pesticides, medicines and drinks (WO
00/44508). During manufacture, the bottles are marked with patterns of
fluorescent ink, according to what they will contain—a blue triangle for
hazardous waste and a green triangle for safe beverages. A waste sorter detects
the shape and colour of the fluorescent patch, and mechanical arms channel the
bottles onto appropriate conveyors.