Production of volatile fatty acids (VFAs) from five commercial bioplastics via acidogenic fermentation

The feasibility of producing volatile fatty acids (VFAs) from five commercial bioplastics via acidogenic fermentation by a non-pretreated anaerobic sludge was investigated. Mesophilic, anaerobic, acidogenic batch assays at 1, 10 and 20 g/L feed concentrations revealed the feasibility of producing VFAs from poly-hydroxyalkanoates (PHA), i.e., PHB and PHBV, but not from PBS, PCL and PLA under the test conditions and time. However, only high PHA substrate concentrations (10-20 g/L) resulted in organic overloading and decreasing the pH of the culture broth down to 4-5, which in turn induced the accumulation of VFAs via kinetic imbalance between acidogenesis and methanogenesis. Gaseous carbon (C-CO2 and C-CH4) accounted for 8-35% of the total initial carbon, while C-VFAs represented 10-18%, mainly as acetate and butyrate. This study rep-resents the first systematically assessed proof-of-concept to produce VFAs from PHA, which is key for the design of bioplastic-to-bioplastic recycling (bio)technologies.

Automated summary

The feasibility of producing volatile fatty acids (VFAs) from poly-hydroxyalkanoates (PHA) through acidogenic fermentation was investigated. It was found that VFAs can be produced from PHB and PHBV, but not from PBS, PCL, and PLA. High concentration of PHA substrates resulted in organic overloading and accumulation of VFAs.