Biological Methods and Techniques for Plastic Waste Valorization

The exponential rise in plastic production and consumption has led to an alarming accumulation of plastic waste in terrestrial and marine environments. Traditional plastic disposal methods such as incineration and landfilling have proven inadequate due to environmental toxicity, greenhouse gas emissions, and the persistence of plastics in nature for hundreds of years. This chapter delves into the promising domain of biological methods and techniques for plastic waste valorization—transforming waste into value-added products through microbial and enzymatic action. We provide a comprehensive overview of the biodegradation potential of various plastic types, including polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), and biodegradable alternatives such as polylactic acid (PLA). A detailed discussion is presented on bacterial and fungal species known to degrade plastics, the enzymes involved (e.g., PETase, cutinase, laccase), and bioengineered strategies using synthetic biology and metagenomics. Bioconversion pathways leading to the production of biosurfactants, organic acids, and biopolymers are also examined. Case studies and recent research breakthroughs demonstrate practical examples and industrial feasibility. The chapter concludes with an analysis of current limitations, future directions, and how policy, innovation, and interdisciplinary collaboration can support the integration of biological valorization methods into mainstream plastic waste management strategies.