11 - Nanobiodegradation of plastic waste

Abstract

Plastics are high molecular mass organic polymers obtained mostly from various hydrocarbons of petrochemicals. Over the past 50 years, plastic materials have been used as a substitution of metal, wood, and paper for many applications because of their excellent features in terms of stability, lightness, low cost, and durability. These polymers are basically nonbiodegradable with only a few exceptions. Poor behavior in communities toward the proper disposal of plastic wastes poses significant threats to the environment. Plastic waste consists of polypropylene, low and high-density polyethylene, polystyrene, polyethylene tetrachloride, polyvinyl chloride, and so forth. Plastic additives of concerns to health and environment include bisphenol A, organotin, triclosan, phthalates, and brominated flame retardants. The current methods used for plastic waste management include incineration, landfilling, chemical, and mechanical recycling. Because plastics are quite recalcitrant type materials, the combined approach using photochemical or thermochemical processes, followed by bioprocessing, is an excellent example of plastic waste management. Biodegradation of plastics is a biochemical process in which a particular compound ultimately breaks into very simpler molecules by the action of enzymes. Plastics are usually biodegraded partly aerobically in soil and compost and anaerobically in landfills and sediments. Aerobic biodegradation produces water and carbon dioxide, while water, carbon dioxide, and methane are produced during anaerobic biodegradation. Biodegradation of plastic waste materials may result in the formation of nanoplastics.