Pyrolysis, Microwave, Chemical and Biodegradation Methodology in Recycling of Plastic Waste: a Circular Economy Concept

Plastics established as an inevitable material in this modern era due to its easy production, processing, cheaper cost and easy use. High demand for plastics leads to tremendous increase in global production over the years. Overproduction of plastics leads to many harmful effects such as waste accumulation in landfill, serious air and water pollution and associated environmental and climate changes. Insufficient regulation in controlling the plastic production primes to research organizations to focus more on the methods of reducing, reusing and recycling concept. Many challenges are involved in recycling plastics especially on the methods and products. Degradation is one among the methods that is widely used. This is very much essential not only to conserve non-renewable fossil fuels, but also avoids further damage to nature. Potential process techniques such as pyrolysis, biological degradation and chemical methods contribute tremendously. Plastics or polymers that are entering into water streams such as rivers and sea can neither be recycled nor incinerated but can be degraded through biodegradation process. Understanding interactions between the natural and synthetic polymers with microorganisms in microbial degradation is very important for the biochemical changes. In this review, conversion methods such as pyrolysis, microwave treatment and material-based processes such as biodegradation and chemical methods are employed to strive for the concept of the circular economy. A brief summary of progress in the recycling of plastic waste into organic compounds, oils and chemicals from virgin polymers or plastics with the use of the above methods are also highlighted.