Solutions to Plastic Pollution

Because poly(alkenes) do not biodegrade, the way plastic waste is handled matters. The main options, from best to worst, are:Reduce and reuse. Using less plastic, and using items more than once, saves raw materials and energy and creates no waste to treat.Mechanical recycling. Waste is sorted by polymer type (the recycling code number on an item shows which), then washed, shredded, melted and remoulded into new products. Sorting is essential, because mixed polymers give a weak material, and quality falls each time a plastic is recycled.Feedstock recycling. Polymers are heated to crack them back into monomers and other small hydrocarbons, which are used as a feedstock to make new plastics or fuels. This can handle mixed waste.Incineration with energy recovery. Waste is burnt and the heat generates electricity. It reduces landfill, but releases CO₂, a greenhouse gas. Burning PVC also releases toxic, acidic hydrogen chloride, HCl, which must be removed from the waste gases by reacting it with a base (for example in a scrubber containing calcium oxide).Landfill is the last resort: it uses up land and the plastic remains for centuries.Biodegradable alternatives, such as PLA made from plant sugars, can replace poly(alkenes) for some single-use items, although they often need industrial composting to break down.Recycling also conserves crude oil, the raw material for most polymers, and usually uses less energy than making new plastic.