Comprehensive Techno-environmental Evaluation of a Pilot-Scale PHA Production from Food Waste in China

Polyhydroxyalkanoates (PHAs), a biodegradable plastic that might replace petroleum-based plastics, can be recovered from organic waste using mixed microbial cultures (MMCs). Research in this field has been ongoing for about 25 years and is now in a critical commercialization period. However, few pilot-scale studies are available to analyze its technical feasibility and environmental impact. We ran an MMC PHA production pilot plant for 6 months using local food waste as the feedstock. The traditional three-stage process achieved PHA content of 47.91 ± 1.91% dry cell weight and volumetric productivity of 9.94 ± 0.01 g/L·d, while a novel rapid proliferation stage was built in, the PHA content and productivity could reach 41.39 ± 2.39% cell dry weight and 20.02 ± 0.01 g/L·d, respectively. Life cycle assessment using field data showed that greenhouse warming potential was much more than five times that of the known literature, and the fossil depletion potential was 10.30 (scenario #1)/7.59 (scenario #2) times higher than petroleum-based polyethylene (PE) plastic. However, establishing a resource-energy-water union instead of an isolated plant could achieve environmental benefits compared to PE plastic. This techno-environmental analysis provides emerging MMC PHA producers worldwide with a valuable reference for further development opportunities and market planning.