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.
Highlights
PHA is a group of 3-hydroxy fatty acid polyesters derived naturally from various types of microbes
The results indicate that the breakeven price (BP) of PHA can be largely influenced by the type and price of cheese by-product feedstock
A techno-economic analysis study has been conducted on the PHA production system by using cheese processing by-product streams as feedstock
Summary
PHA is a group of 3-hydroxy fatty acid polyesters derived naturally from various types of microbes. It has thermoplastic properties and ecological characteristics, such as renewable origins and is biodegradable in the natural environment. PHA has been an emerging bioplastic material in recent decades and has become a popular alternative for conventional petroleum-based plastics [1,2]. PHA has a well-established commercial market and has been made into various products (e.g., packaging films, plastic containers, medical implant materials, drug carriers, nutritional supplements and biofuels, etc). PHA is produced globally at industrial scale (for example, 50,000 metric ton/year (MT/a) by ADM, USA (with Metabolix), 10,000 MT/a by Bio-On, Italy, and 10,000 MT/a by Tianjin Green Bio-Science, China) [3]. The PHA market is around $0.72 billion in
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