Recovery of Polyhydroxyalkanoate from Enriched Biomass: A Novel Sustainable Extraction Protocol

Polyhydroxyalkanoates (PHAs) have recently been established as one of the main biopolymer alternatives to conventional petroleum-based plastic materials. They can be produced by mixed microbial cultures available in the sewage sludge, thus allowing the spread of a circular economy approach in the water sector. Despite being easily produced, PHA extraction was poorly investigated. In this context, this study presents the preliminary promising results of a new extraction procedure of PHA by bio-based organic solvents. PHA-rich biomass was produced by a pilot plant, adopting aerobic dynamic feeding as a strategy to enrich the mixed microbial cultures. The PHA accumulation was performed by controlled pulsate-feeding, controlled automatically by a homemade software. PHA-rich biomasses were treated following the standard extraction protocol with chloroform and comparing the results with different green protocols. Treatment with organic green solvents such as 2-methyl tetrahydrofuran (2-Me-THF) avoid the use of water during purification. Preliminary extraction results highlighted the high efficiency of 2-methyl tetrahydrofuran (PHA extraction yield: 69.1%) compared to ammonium laurate (42.3%) and chloroform (46.4%), thus indicating a promising environmentally friendly procedure to recover PHA.