Читать книгу Plastics Process Analysis, Instrumentation, and Control - Группа авторов - Страница 43

The current issues of plastic waste pollution in the world have been handled in a monograph (62). This monograph covers most aspects of plastic, from its chemical makeup and manufacture to its various recycling possibilities and, in many cases, its final, unfortunate resting place in a landfill, soil, and the sea. Also, the economic, ecological, and technical aspects of plastic waste handling have been discussed in a monograph (63).

Waste plastics, that is, synthetic polymer-containing substances, are an environmental issue because of the problems associated with disposing of a large volume of non-biodegradable material.

It has been estimated that plastics account for about up to 15% by weight and 25% by volume of municipal solid waste produced in the United States (64). Increasing amounts of scrap and waste plastics have created an ever-expanding disposal problem for both industry and society in general. The increased popularity of bottled water has led to a huge increase in the amount of plastic bottles appearing in the municipal solid waste stream. The amount of plastic bottles sent to landfills has increased so much that several cities on the West Coast of the United States are considering bans on the sale of water in disposable plastic bottles.

Incineration, landfilling waste-to-energy and recycling are the main techniques used for the disposal of plastics (64). However, there are many problems associated with disposing of plastics.

One problem is that it takes a large amount of energy to incinerate plastic and the incineration process produces many products that are harmful to humans and the environment such as carbon monoxide, carbon dioxide, chlorine, and other hydrocarbons. These gases may also contribute to the global warming problem.

Another problem is that placing plastics in landfills takes a large amount of energy and landfill space. It takes many gallons of gasoline to bury a ton of plastic with machinery such as bulldozers in a landfill. Landfill space is increasingly becoming more scarce due to environmental problems associated with storing municipal wastes.

Another problem is that waste-to-energy conversion using plastics is not very efficient. Typically the energy used to convert fossil fuels to plastic is lost when plastics are burned for energy since waste-to-energy combustion is a relatively inefficient means of energy recovery (64).