Biopolymer production using volatile fatty acids as resource: Effect of feast-famine strategy and lignin reinforcement

Abstract

The present study aimed to investigate the biopolymer production using VFA's as carbon source through feast and famine strategy in a sequencing batch reactor. Famine condition with nutrients and oxygen limitation resulted in high polyhydroxybutyrate yield (PHB: 2.65 ± 0.012 g/L; 0.36 ± 0.015 gPHB/gVFA) than feast mode (0.26 ± 0.02 g/L; 0.034 ± 0.013 gPHB/gVFA). Repeated batch operations induced substrate consumption, wherein acetate utilization was high in both the conditions (feast: 83%, famine 74%) followed by butyrate (feast: 74%, famine 72%). Besides, high biomass concentration was also observed in feast condition (3.45 ± 0.14 g/L VSS), while oxygen and nutrients limitation in famine mode regulated the carbon use for biomass growth (2.46 ± 0.15 g/L VSS). Further, PHB grafting with lignin (3% and 5%) exhibited increased thermal stability than pristine PHB. Biopolymer production using VFA's as carbon source and utilization of lignin as functional filler for strengthening PHB offer lignin valorization also wider its applications specifically in the biomedical field.

Keywords: Acetate and butyrate; Feast and famine; Mixed culture; Polyhydroxybutyrate; Sequencing batch reactor.