Evaluation of Biodegradation of Plastics

Currently, our world is facing many challenges such as increase in waste flows, energy depletion and climate changes. In addition, global plastics production exceeds 180 million tons per year with yearly increase in supply and demand (Cutter, 2006). These plastics turn to solid waste after their end of life and will accumulate in the environment. Hence, the production of biodegradable plastics is important from an environmentally friendly point of view to reduce the accumulation of plastic waste in the environment (Lovino et al., 2008). Petroleum-based plastic products are characterized as not easily degradable because of their relatively high stability and hydrophobic characteristics (Lovino et al., 2008).

Biodegradable plastics offer a lot of advantages such as increased soil fertility, low accumulation of bulky plastic materials in the environment (which invariably will minimize injuries to wild animals), and reduction in the cost of waste management. Furthermore, biodegradable plastics can be recycled to useful metabolites (monomers and oligomers) by microorganisms and enzymes. A second strategy involves degradation of some petroleum-derived plastics by biological processes. A typical example can be seen in the case of some aliphatic polyesters such as Polycaprolactone (PCL) and Polybutylene succinate (PBS) that can be degraded with enzymes and microorganisms [Tokiwa et al.,1976, Tokiwa and Suzuki, 1977a; Tokiwa and Suzuki, 1977b].