According to ASTM standard D-5488-94d and European norm EN 13432,
‘‘biodegradable’’ means ‘‘capable of undergoing decomposition into carbon
dioxide, methane, water, inorganic compounds, and biomass’’. The predominant
mechanism is the enzymatic action of microorganisms, which can be measured by
standard tests over a specific period of time, reflecting available disposal
conditions. There are different media (liquid, inert, or compost medium) to analyze
biodegradability. Compostability is material biodegradability using compost
medium. Biodegradation is the degradation of an organic material caused by
biological activity (biotic degradation), mainly microorganisms’ enzymatic action.
The end-products are CO2, new biomass, and water (in the presence of oxygen,
i.e. aerobic conditions) or methane (in the absence of oxygen, i.e., anaerobic
conditions), as defined in the European Standard EN 13432-2000. Depending on
the type of standard to follow (ASTM or EN), different composting conditions
(humidity and temperature cycle) must be realized to determine the compostability
level [2]. Therefore, the comparison of the results obtained from different
standards seems to be difficult or impossible. We must also take into account the
amount of mineralization as well as the nature of the residues (commonly called
‘‘by-products’’) left after biodegradation [3]. The accumulation [4] of contaminants
with toxic residues can cause plant growth inhibition. The key issue is to
determine the environmental toxicity level for these by-products, which is known
as eco-toxicity [5]. Some general rules enable the determination of the biodegradability
evolution. For example, an increase in parameters such as the hydrophobicity,
the macromolecules molecular weights, and the crystallinity or the size
of crystalline domains decreases the biodegradability [6].