A comparative analysis of biopolymer production by microbial and bioelectrochemical technologies

Abstract

Production of biopolymers from renewable carbon sources provides a path towards a circular economy. This review compares several existing and emerging approaches for polyhydroxyalkanoate (PHA) production from soluble organic and gaseous carbon sources and considers technologies based on pure and mixed microbial cultures. While bioplastics are most often produced from soluble sources of organic carbon, the use of carbon dioxide (CO₂) as the carbon source for PHA production is emerging as a sustainable approach that combines CO₂ sequestration with the production of a value-added product. Techno-economic analysis suggests that the emerging approach of CO₂ conversion to carboxylic acids by microbial electrosynthesis followed by microbial PHA production could lead to a novel cost-efficient technology for production of green biopolymers.

Fig. 1. PHA production from liquid and gaseous sources of carbon in (A) single stage fermentation, (B) two stage fermentation, and (C) two stage microbial electrosynthesis process.

Fig. 2. (A) Effect of productivity at different values of PHA yield on PHA production costs and (B) effect of PHA yield at different productivity values on the cost of PHA production. A production capacity of 9000 tons per year, an overall yield of 0.24 g PHA per (g substrate), and an overall cost of the carbon source of $0.5 per kg were assumed.

Fig. 3. Dependence of productivity on the carbon source used for PHA production. In heterotrophic–autotrophic fermentations either fructose or glucose was used for biomass growth, while a gas mixture consisting of CO₂, H₂ and O₂ was used for PHA production.