Biodegradation of Plastics at Home Composting Conditions

Plastics have become an ever increasingincremental environmental pollution problem since high amounts of them are dumped every year into the environment. To remediate this problem, many proposalsnovel easily-biodegradable plastics have been developed either through the use of novel polymers or via the addition of prodegradant catalyst (often a salt of manganese or iron) such as OXO-plastics. These are advertised as low-persistant in the environment and easily converted into safe non-polluting products by natural tropic process. attempt to produce new plastics with the same good characteristics as the old ones, but with an increased biodegradability so that they can remain only a few months in the environment before they can be turn into safe non-polluting natural products by microbes. For instance Polylactic Acid based plastic (PLA) is a widely used biodegradable-compostable material which claim to be biodegradable principally under specific conditions.One example of these materials is the polylactic acid based plastic (PLA), which is presented as a biodegradable-compostable material but usually with a warning that they perform in this way under special conditions. I In this work, we evaluate the biodegradability of PLA, Polyethylene and other Oxo-biodegradable plastics in a composting system under normal atmospheric conditions with an average of temperature around of 24 C, in order to establish its compostability in typical conditions of tropical countries. Results obtained by monitoring the integrity and weight of plastic pieces, and by NMR over time reveal that none of the materials was biodegraded after 31 weeks (7 months) under the conditions studied. On the other hand, microbial communitiesamplicon sequencing of the 16S rRNA analysis showed the presence of bacterial groups identified previously on the degradation of biodegradable plastics (e.g. Methylotrophs and Actinobacteria), and are aligned with previous studies that conclude that plastics considered as biodegradable have an influence over the soil microbiomamicrobiome. This work contributes to the establishment of which plastic materials should be classified as biodegradable in prevailing conditions in tropical countries.