Biodegradation of Plastic Waste

Abstract

Plastic waste has greatly contributed to water and land pollution worldwide and marine plastic waste has caused havoc on numerous biological species. Most plastics are fossil-based and cannot be fully degraded by microorganisms. Bio-based plastics derived from biomass, such as starch or cellulose, can be generally degraded into CO2 and microbial biomass. Recent scientific studies have shown that several pro-degradant additives did not perform, as claimed by plastic processors, under standard biodegradation conditions. Life cycle assessment studies in the United States and Canada confirm that the standard polyethylene grocery bag has significantly lower environmental impacts than a 30% recycled content paper bag. Major factors that differentiate cradle-to-grave impacts of plastics and alternative packaging materials include: (a) less weight of plastic material required to perform same packaging function, (b) lower water consumption per kg of plastics compared to alternatives, (d) no methane releases for land-filled plastics and (e) higher energy credits for plastics disposed via waste-to-energy combustion. A Dutch study showed that substitution of fossil-based plastics by bio-based polymers generally leads to lower non-renewable energy use and reduced greenhouse gas emission. Research at the University of the Philippines (UP) deals with the utilization of agricultural by-products, such as chitin and cellulose, to make bioplastic film for packaging. Nanoclay was also incorporated to produce a nano-composite polymer. Plastic degrading microorganisms have been isolated by UP researchers from local sources including plant root nodules, alkaline spring and soil samples. The following policies regarding plastic products are being recommended under Philippine conditions: (a) government incentives for processors/manufacturers of biodegradable plastic products, (b) restricted importation and sale of non-biodegradable, esp. single-use, plastic products, and (c) funding and logistical support for R & D on commercial additives for plastic biodegradation, local production of bioplastics and isolation of plastic-degrading microorganisms.