Techno-economic analysis on an industrial-scale production system of polyhydroxyalkanoates (PHA) from cheese by-products by halophiles

Abstract

Polyhydroxyalkanoates (PHA) are a family of biodegradable plastics used as an ecofriendly alternative for conventional plastics in various applications. In this study, an industrial-scale PHA production system was designed and analyzed for the material flows and economics with the use of SuperPro Designer. Haloferax mediterranei was utilized to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Byproduct streams from a local cheese plant, with an input of 168.7 metric ton/day (MT/day) lactose, were used as the feedstock. Three scenarios with different processes for the treatments of used enzyme and spent medium were investigated and the major factors that influence the overall economics were identified. The simulated system produces 9700 MT/year PHBV with a yield of 0.2 g PHBV/g lactose and an overall process efficiency of 87%. The breakeven price was found to be more sensitive to the lactose price than enzyme price. The scenario with enzyme reuse and spent medium recycling achieved the lowest breakeven price among others, which can be less than 4 $/kg PHA based on the delactosed permeate (DLP) unit price. The study suggests utilizing dairy derived feedstocks has the potential to make PHA competitive in the bioplastic market, which could be beneficial to both dairy and bioplastic industries.