Chlorine-free Extractions of Mixed-Culture Polyhydroxyalkanoates Produced from Fermented Sewage Sludge at Pilot Scale

In this study, various conventional and innovative methods were investigated for the recovery of polyhydroxyalkanoates (PHA) from a single batch of biomass produced at a pilot scale from mixed microbial cultures (MMCs) and fermented sewage sludge as a feedstock. Sustainable chlorine-free methods using NaOH and/or H2O2, as well as extraction in nontoxic ethyl acetate, were analyzed. Interestingly, the combined treatment of biomass with NaOH and H2O2 solutions demonstrated good recovery (70 wt %) and high purity (92 wt %) of the polymer in small-scale trials. Moreover, when the coupled treatment was performed on a larger biomass quantity (approximately 200 g), it achieved high purity and recovery yield (93 and 88 wt %, respectively), indicating the feasibility of this extraction method on a larger scale.