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Polyhydroxybutyrate Production from Waste Frying Oil Using Bacillus megaterium: Process Optimization and Economic Analysis and Life Cycle Assessment
Author(s)
Tojumsi, Wacharakorn
Date Issued
January 1, 2025
Type
Article
Abstract
This study optimized polyhydroxybutyrate (PHB) production from waste frying oil using Bacillus megaterium and evaluated the economic and environmental performance of the process. Free fatty acid (FFA) content, nitrogen concentration, and temperature were examined using a Box–Behnken design. The optimal conditions were 3.18 mM nitrogen, 1.20% FFA, and 35 °C, which produced 58.7% PHB in bacterial dry mass and a maximum yield of 8.9%. The regression models showed high predictive accuracy with errors between 0.6 and 14.7%. Techno-economic analysis showed that chemical use during fermentation and solvent extraction dominated operating costs. For plant capacities of 100 to 400 m3, the minimum selling price ranged from 35.36 to 23.70 USD/kg, depending on selling price and cost variation. Life cycle assessment estimated a carbon footprint of 3.94 kg CO₂-eq/kg PHB, mainly from electricity and solvents. Using renewable electricity and greener or solvent-free extraction could reduce emissions by up to 38%. Overall, waste frying oil is a promising substrate for PHB production, and integrating optimization with economic and life cycle assessment supports the development of sustainable bioplastics.
Citation
Waste and Biomass Valorization, 2025