Here is the "crash course" or brief insight on plastic recycling or plastic waste management:
Plastic usage (aa) generates Plastic Waste (a). If not reusable (b), then such plastic waste needs to be subjected to a suitable method of plastic waste management (c to aa). Globally, more than 95% of plastic waste is not segregated and ends up in landfills (d), rivers & oceans. Segregation (e) produces better quality plastic waste (f). Such segregation (e) of plastic waste generally involves air-density segregation, shredding, washing and drying to remove the non-plastics substances like moisture and dirt. Next step is the classification of the segregated plastic (f) waste into Mono-polymer plastic waste (h), multi polymer plastic waste (i), multi-material plastic waste (k).
Recycling of clean mono-polymer (h) plastic waste is the most prevalent practice for plastic recycling. Examples of clean Mono-polymer (h) plastic waste recycling are:
Clean and segregated Mono-polymer (h), poly-ethylene or polypropylene undergoes Mechanical recycling (h1) through extrusion and granulation to produce plastic granules (y) These plastic granules (y) can be used for manufacturing new plastic products (z).
Waste water-bottles are made of PET (polyethene terephthalate). PET is recycled by using de-polymerisation based chemical recycling (h2) to make polyester fiber. The polyester fiber is used for making new plastic granules (y) of PET.
Multi-polymer (i) and Multi-material (k) plastic waste can be recycled mechanically using 20% plasticiser (j) to manufacture substandard plastic granules. The role of plasticiser is to bind mixed and brittle plastic into a solid block to make plastic granules. These plastic granules do not possess much strength and can only be used for limited Low-Quality Applications (j1) like thick benches and thick tables. High-quality plastics like carry-bags cannot be manufactured from these granules (i). Major limitations of Low-Quality Application of mechanical recycling using plasticiser (j &j1) are:
Extended Producer Responsibility (EPR) is attached to this activity because new plastics are being manufactured.
These plastic products have a limited life. The plastic products with 20% plasticiser cannot be further recycled using mechanical recycling.
Ultimately, every Plastic Waste reaches End-of-Life (i) when it cannot be mechanically recycled anymore. Currently, 95% of the plastic waste generated is end-of-life and reaches landfills, rivers and oceans. However, we have the following options for disposal of End-of-Life Plastic Waste:
Incineration in Cement Kiln (m): Most of the cement kilns are located very far from the source plastic waste generation. Cement kilns are usually located at the source of the limestone. For example, the nearest cement kiln to Mumbai is at Chandrapur, which is 840km away. High transportation cost makes the Cement Kiln (m) option unviable. Cement kiln is not a circular economy solution for plastic waste. Burning of plastic waste in cement kiln generates toxic gases that need to be treated before releasing to the environment. Other than the cement kiln, there are 3 other technology options: Gasification (p), Incineration (q) & Pyrolysis (r).
Plastic waste Gasification (p) has not been successful at commercial scale due to process complications and the presence of contaminants in plastic waste.
Plastic waste incineration (q) projects to generate electricity have not been largely profitable in India nor the Netherlands. During plastic waste incineration (q), plastic waste is burned. Burning of plastic waste generates toxic gases that need to be treated before releasing to the environment. Only 30% of the energy in plastic gets converted into steam (q1); out of which only 70% of the energy in the steam generated gets converted into electricity (q2). Therefore, the use of incineration to generate electricity (q, q1, q2) is not very profitable because less than 25% of energy in plastic waste actually gets converted into electricity.
APChemi’s Plastic Pyrolysis Technology (f) is proven for chemical recycling of end-of-life plastic waste. In the pyrolysis process, more than 80% of the polymer hydrocarbons and energy is recovered (s). Moreover, APChemi's pyrolysis oil purification technology helps insubstantial up-gradation of the paralysis soil quality. The end product of Plastic Pyrolysis are hydrocarbon oil, gas and residue. Hydrocarbons recovered from plastic waste have the following applications:
Applications as Fuel:
Hydrocarbons recovered from plastic waste is used as fuel for generating heat in industrial application such as the generation of steam, hot water, hot air or heating thermic fluid.
Pyrolysis oil is further fractionated into petrol, diesel & jet fuel (u1). in running petrol and diesel engines.
Hydrocarbons recovered from plastic waste can be fired in an internal combustion engine (v) to produce electricity.
Applications as Circular-economy for plastics: Alternatively, pyrolysis oil and hydrocarbon gas produced from plastic waste is an excellent substitute for crude oil to manufacture sustainable petrochemicals (x) and new plastics (y). Therefore, pyrolysis (r) is an important step in creating a sustainable circular economy for end-of-life plastic waste.