Four techniques and schemes are used in plastic solid wastes (PSW) treatments, which are primary (re-extrusion), secondary (mechanical), Tertiary (chemical), and quaternary (energy recovery). Primary recycling, re-extrusion technique is usually used in the producing line itself where clean junk of single polymer is reused to obtain new products of the same material. Different waste products that are either end-of-life or junk are usually used as the primary material of secondary techniques; thus, the overall shape and form are decreased to be more likable such as granules, chips, or fine particulates relying on the origin, form, and ease of use. Recently, Tertiary treatment techniques have significant contributions to the recycling process of PSW. Advanced thermo-chemical treatment methods are the major technologies used which produce either fuel or petrochemical raw materials. A valuable PSW in both wastes generally and a municipal solid waste especially is energy recovery. Even when re-extrusion and chemical treatment techniques are more applied, it’s noticed that thermo-chemical and energy recovery treatment techniques are more powerful and worthy of being more studied.