Polyhydroxyalkanoates (PHAs), such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymers, are biopolymers that can serve as substitutes for conventional plastics as they have similar properties. The objective of this study was to develop a robust mixed microbial culture (MMC) enriched in microorganisms capable of accumulating high intracellular PHBV content. The MMC was successfully enriched and operated stably over the long term (521 days) in a sequencing batch reactor (SBR) in which the carbon and nitrogen feeding were uncoupled. Its maximum PHBV accumulation capacity and biopolymer production yield were 62 weight (wt.) % and 0.59 Cmol PHBV /Cmol VFA , respectively, and treated OLRs of up to 6 g COD/(L·d), which influenced the microbial community composition. The maximal accumulation capacity of the MMC, evaluated in batch experiments, was 83 wt. % PHBV and yields of 0.63 Cmol PHBV /Cmol VFA . Similar results were obtained with the two synthetic volatile fatty acid (VFA) compositions tested. When the potential of this culture to use pre-acidified (VFA-rich) wastewater from fish canning residues as a substrate was evaluated, the highest obtained values were 56 wt. % PHBV and 0.36 Cmol PHBV /Cmol VFA . The results demonstrate that PHBV composition can be adjusted by VFA feed composition (either synthetic or residual), highlighting the process versatility. • MMC with high storage capacity in the enrichment stage (62 wt. % PHBV) • Long term stable operation even at an OLR of 6 g COD/(L·d) was achieved • Proven versatility led to 83 wt. % PHBV with synthetic and 56 wt. % with residual VFA • Targeted PHBV compositions do not depend on the VFA source • Upstream treatment should be considered to avoid biological inhibitory events
Lopez-Garabato et al. (Sun,) studied this question.