Techno-economic evaluation of an integrated biorefinery concept generating polyhydroxyalkanoates and value-added products from biodiesel industry by-products

Biodiesel production from oilseeds generates significant quantities of crude glycerol and oilseed meals as by-products. This study focuses on techno-economic evaluation of a novel integrated biorefinery concept focusing on valorization of sunflower meal (SFM) and crude glycerol for the production of polyhydroxyalkanoates (PHAs) together with protein isolates and antioxidant-rich extracts as co-products for value-added applications. This process could be also employed in the case of other oilseeds utilised for biodiesel production. Industrial production of various members of the poly-ester family of PHAs is hindered by the high production cost mainly attributed to the fermentation media employed, the fermentation stage and the downstream separation stage. This study presents the effect of co-product generation, crude nutrient supplement production and integration of utilization of crude enzymes produced by solid state fermentation in different stages of the whole process, in the production cost of PHAs. PHA production was achieved via fermentation of crude glycerol and SFM hydrolysates after fractionation of value-added co-products. Crude enzymes generated via solid state fermentation were employed for production of fermentation nutrient supplements, protein isolate hydrolysis and lysis of bacterial cells to isolate PHA granules as an alternative to conventional methods (e.g. commercial enzymes, chemical treatment). Techno-economic evaluation included estimation of total capital investment and total production cost leading to the determination of the unitary production cost for PHAs following the integrated biorefinery scheme proposed in this study.

Acknowledgements

This work is part of the “BIOREF” project (09SYN-81-715), implemented within the NSRF 2007-2013 and co-financed by National and Community Funds.