Environmental life cycle analysis (LCA) of polyhydroxyalkanoate (PHA) production : a techno-environmental assessment

Abstract

Polyhydroxyalkanoate (PHA) is a type of biodegradable polymer derived from renewable sources expected to serve as a viable alternative to petrochemical plastics. The aim of this study is to assess the feasibility of utilizing wastewater treatment plant (WWTP) sludge as a feedstock for PHA plastic production in Finland, with a focus on a centralized extraction site in the Lahti region. A comprehensive cradle-to-gate Life Cycle Assessment (LCA) using GaBi software is performed to evaluate the environmental impacts associated with the production of PHA. A particular attention is paid to assess the Global Warming Potential (GWP), Acidification Potential (AP), and Eutrophication Potential (EP) of PHA production. A detailed analysis of the different processes and their impact on the total GWP is also carried out. The results show that the total GWP of PHA production is roughly 4.5 and 2.0 times higher than PolyPropylene (PP) and PolyEthylene Terephthalate (PET) as commonly used petroleum-based plastics. In addition, it has been found out that acidogenic fermentation and drying processes are the most electricity and heat consumers, respectively compared to other processes. Hence, they have a remarkable contribution on the overall environmental impact, and they should be carefully considered in the sustainability assessment of PHA production. The findings clearly highlight the importance of LCA analysis for the environmental assessment of the PHA production while addressing the processes with the highest environmental impacts. This may provide a scientific guideline for further development of sustainable PHA production in the future.