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ENCYCLOPEDIA OF ENVIRONMENTAL SCIENCE AND ENGINEERING - RECYCLING WASTE MATERIALS

Tái chế phế liệu Khai hoang phế liệu với mục đích tái sử dụng là một định nghĩa thường được chấp nhận tái chế. Mặc dù nước là chất tái sử dụng trong khối lượng lớn nhất, nó sẽ không được đề cập ở đây. (Xem sinh học điều trị của nước thải, nước thải thành phố, điều trị vật lý và hóa học của nước thải, tái sử dụng nước, xử lý nước). Các tạp chất trong không khí được coi là chỉ sau khi loại bỏ. Baghouses là một ví dụ. Tái chế, tái sử dụng, dựa trên kinh. | RECYCLING WASTE MATERIALS Reclamation of waste materials for the purpose of reuse is a commonly accepted definition of recycling. Although water is the substance reused in greatest volume it will not be covered here. See Biological Treatment of Wastewater Municipal Wastewater Physical and Chemical Treatment of Wastewater Water Reuse Water Treatment . Impurities in the air are considered only after removal. Baghouses are an example. Recycling or reuse is based on economics. A used material will be discarded if reclamation costs exceed the cost of new virgin material. Disposal costs however have increased greatly in the last decade and it is no longer as easy to throw away many things. Acceptable disposal sites increasingly are in short supply and transportation costs have become a much more significant part of the expenses of disposal. A typical municipal solid waste can be expected to be somewhat close to the following by weight Paper 35 Yard wastes 16 Food wastes 15 Metals 10 Glass 10 Plastics rubber and leather 7 Textiles 2 Miscellaneous 5 These percentages will vary with the season. More acute public awareness of environmental pollution has added to the pressure for recycling. Resources are not limitless and many non-renewable materials will be seriously depleted in the not-too-distant future. Raw materials for plastics are petroleum based. Oil has not had a very stable price since the early 1970 s. Landfills have served as repositories for municipal and industrial solid wastes since before the turn of the century. Waste was placed in a dump without regard to separation or segregation of materials. Odors and rodents were common problems. Little planning went into site selection of solid waste disposal areas. As urban areas grew many dumps at the edge of town were bypassed and were then within the city limits. In many cases these sites were covered and homes and buildings constructed. These structures all too frequently settled unevenly on the poorly compacted .