Microbial community-based polyhydroxyalkanoates (PHAs) production from wastewater: Techno-economic analysis and ex-ante environmental assessment

Abstract

This work investigates the potential for polyhydroxybutyrate (PHB) production from wastewater, from a techno-economic and an environmental perspective, examining scale-up opportunities and bottlenecks prior to commercialisation. Conceptual process design, economic, environmental impacts and sensitivity analysis are developed for one fermentation process and three downstream processing routes, based on alkali, surfactant-hypochlorite and solvent treatments. Environmentally and cost-wise, the alkali treatment is the most favourable with production costs of 1.40€/kg PHB, global warming potential of 2.4kgCO2-eq/kg PHB and non-renewable energy use of 106MJ/kg PHB. The solvent-based process yields the highest costs and environmental burdens: 1.95€/kg PHB, 4.30kgCO2-eq/kg PHB and 156MJ/kg PHB. The production of PHB from wastewater is identified as an interesting alternative to pure culture-polyhydroxyalkanoates production from sugars. However, these results are not yet competitive with those for the petrochemical counterparts. Additional performance improvements may be possible, through process integration and optimisation.

Keywords: Circular economy; Economic evaluation; Life cycle assessment; Polyhydroxyalkanoates; Waste valorisation.