Degradation of Plastics under Anaerobic Conditions: A Short Review

Abstract

Plastic waste is an issue of global concern because of the environmental impact of its accumulation in waste management systems and ecosystems. Biodegradability was proposed as a solution to overcome this problem; however, most biodegradable plastics were designed to degrade under aerobic conditions, ideally fulfilled in a composting plant. These new plastics could arrive to anaerobic environments, purposely or frequently, because of their mismanagement at the end of their useful life. This review analyzes the behavior of biodegradable and conventional plastics under anaerobic conditions, specifically in anaerobic digestion systems and landfills. A review was performed in order to identify: (a) the environmental conditions found in anaerobic digestion processes and landfills, as well as the mechanisms for degradation in those environments; (b) the experimental methods used for the assessment of biodegradation in anaerobic conditions; and (c) the extent of the biodegradation process for different plastics. Results show a remarkable variability of the biodegradation rate depending on the type of plastic and experimental conditions, with clearly better performance in anaerobic digestion systems, where temperature, water content, and inoculum are strictly controlled. The majority of the studied plastics showed that thermophilic conditions increase degradation. It should not be assumed that plastics designed to be degraded aerobically will biodegrade under anaerobic conditions, and an exact match must be done between the specific plastics and the end of life options that they will face.

Bridging Three Gaps in Biodegradable Plastics: Misconceptions and Truths About Biodegradation

“…Incinerating is not a desirable mode for fossil-based biodegradable plastics, as it consumes a high amount of energy and emits greenhouse gases (Razza et al, 2015;Folino et al, 2020a). Also, some biodegradable products may not have completed their life cycle when landfilled (Shin et al, 1997;Quecholac-Piña et al, 2020).…”

The phylogenetic and global distribution of bacterial polyhydroxyalkanoate bioplastic degrading genes

“…Composting expands the end-of-life options available for bioplastics and is particularly beneficial when mechanical recycling is not an option (31). However, composting requires existing infrastructure and collection systems and access to these varies based on locale (82).…”

“…A large fraction of plastic waste is disposed of in landfills. Despite landfills being a likely site of disposal, very little characterization of the biodegradation of biodegradable plastics in landfills has taken place (82). Very few plastics are recycled due to low consumer compliance, lack of infrastructure, and contamination of recycling streams (3).…”

Influence of the Ultrasonic Treatment on the Properties of Polybutylene Adipate Terephthalate, Modified by Antimicrobial Additive

“…Medicine [ 3 , 4 ] and packaging industry [ 5 ] are some of the numerous industries where various plastics are in demand. At the same time, the problem of environmental pollution is aggravated every year, including the consumption of these materials [ 6 ], therefore, the direction of biodegradable polymers is actively developing—polymers, capable of rapid biodegradation under the influence of environmental factors and microorganisms and having properties similar to traditional polymers [ 7 ].…”