Process optimization for polyhydroxyalkanoate production by mixed microbial cultures within the B-PLAS project

Polyhydroxyalkanoates (PHA) are biodegradable polyesters with comparable properties to some petroleum-based polyolefins. Within the context of the B-PLAS process, the PHA production is integrated with a wastewater treatment process aimed at recovering energy and C through platform molecules such as volatile fatty acids (VFAs). Eventually, selected mixed microbial cultures (MMCs) are provided with a fermentation broth under an aerobic dynamic feeding regime to produce PHA-enriched biomass. In this study, an anoxic/aerobic selection and accumulation process has been explored and compared on a bench scale with the standard and most studied full aerobic alternative. A final setup for both the bench-scale experiments and the B-PLAS pilot plant has also been proposed, allowing to achieve, on-demand, a higher dried biomass PHA content (>50%) compared to the analogous aerobic setup. In addition, the selected population has been proven to respond positively to reduced oxygenation conditions, opening new possibilities to maximise the production of the pilot plant while reducing the oxygenation-related costs and streamlining the process scheme.