Recycling of Waste:
In recycling, some of the used or waste materials are not discarded after their initial use but are processed so that they can be used again. The purpose of recycling is to conserve sources such as raw material and energy. The volume of the waste is also much reduced by recycling of the materials. The most common domestic materials that are recycled are paper, plastic glass, and aluminum.
Recycling of paper:
The largest item which is recycled is newspaper and in its recycling process, the release of chlorine or other bleaching acids and organic solvents is significantly less as compared to the formation of these compounds during the processing of virgin newspaper. To improve the whiteness of the recycled newspaper it is blended with the virgin newspaper or sometimes treated with peroxides and hydrosulfites. In the recycling process, the fiber of the newspaper becomes shorter so it can be recycled again and again for five times.
Recycling of plastics:
The recycling of plastics id done by reprocessing, depolymerization or transformation.
In reprocessing, the used plastics are remelted and used for the synthesis or manufacturing of different products e.g., the original use of polystyrene is for the manufacturing of foam, packaging, cutlery, furniture, etc. but after its reprocessing it is used mostly for the manufacturing of toys, trays, etc.
The depolymerization is a process in which the used plastics are converted back into their original components by a chemical or thermal process so that these can be subsequently polymerized again e.g., polyethylene can be thermally depolymerized in the presence of a catalyst and heat into its original components.
The transformation is a process in which used plastics are converted into low-quality substances which are later used for the production of other materials e.g., cracking of polyethylene at high temperature gives its monomers which are used for the manufacturing of lubricants.