Biodegradability of PHAs

In previous section, we explained that the methods for biodegradability testing have their limits and results of some experiments might be distorted, misleading or just wrong. How can we state the PHAs are really biodegradable?

Hydal PHA biodegradability was tested for fresh and waste water environment according to ISO 14851 standard in BUT Brno. Aerobic biodegradability was 89 % after 137 days, similar to cellulose.

The biodegradability of PHAs has been tested for decades. Polyhydroxyalkanoates are a group of polymers, but just few of them are produced commercially (P3HB, P4HB, PHBV, PHBH and their copolymers). There are slight differences in biodegradability of various PHAs; e.g. copolymers degrade faster than homopolymers thanks to more amorphic inner structure.1, 2 However, due to low effect and high variability in measurements, we discuss PHAs as a uniform group from the biodegradability perspective.

The methods for biodegradability assessment vary a lot among the studies; thus, the results are of low reproducibility. For now, we can clearly state PHAs are biodegradable, but we cannot precisely measure how fast.




(Danimer Scientific)




(RWDC Industries)




Fresh and waste water

ASTM D5271, EN 29408

Vincotte OK biodegradable WATER (S0292)


Vincotte OK biodegradable WATER (S0720)

ASTM D5271, ISO 14851


ASTM D5988

Vincotte OK biodegradable SOIL (S0292)


Vincotte OK biodegradable SOIL (S0720)

ASTM D6400, ISO 17556


Vincotte OK biodegradable MARINE (S0292)

ASTM D7081

Vincotte OK biodegradable MARINE (S0318)

Vincotte OK biodegradable MARINE (S0720)

AST D7081


ASTM D5511


ASTM D5511


Industrial composting

ASTM D6400, EN 13432

Vincotte OK compost INDUSTRIAL (S0292)

ASTM D6400, D6868, EN 13432, Vincotte OK compost INDUSTRIAL (S0318)

Vincotte OK compost INDUSTRIAL (S0720)

ASTM D6400, EN 13432

Home composting

EN 13432 (in lower temperature),

Vincotte OK compost HOME (S0292)

EN 13432 (in lower temperature),

Vincotte OK compost HOME (S0318)

Vincotte OK compost HOME (S0720)


Table 2: The table summarizes biodegradability declarations and certifications of commercial PHAs in respective environments. Nodax PHA (Danimer Scientific, USA) – poly-3-hydroxybutyrate-co-3-hydroxyhexanoate produced from rapeseed oil, Kaneka Biodegradable Polymer PHBH, Aonilex (Kaneka Belgium NM) – poly-3-hydroxybutyrate-co-3-hydroxyhexanoate produced from vegetable oil, Solon PHA (RWDC Industries) – PHA copolymer, Mirel (Telles)P3HB and copolyesters from corn saccharides. (They state on their websites Vincotte OK certification, but it wasn’t successfully verified in Vincotte OK database.)  Adapted from ref.3, actualized.


1 Volova, T. G., S. V. Prudnikova, O. N. Vinogradova, et al. Microbial Degradation of Polyhydroxyalkanoates with Different Chemical Compositions and Their Biodegradability. Microb Ecol. 2017, 73(2): 353-367. doi: 10.1007/s00248-016-0852-3.

2 Meereboer, K. W., M. Misra and A. K. Mohanty. Review of recent advances in the biodegradability of polyhydroxyalkanoate (PHA) bioplastics and their composites. Green Chemistry. 2020, 22(17): 5519-5558. doi,

3 Koller, M. and A. Mukherjee. Polyhydroxyalkanoates – Linking Properties, Applications and End-of-life Options. Chem. Biochem. Eng. Q. 2020, 34(3): 115-129. doi: