A new study from the Universidade de Santiago de Compostela showcases a cutting-edge biorefinery capable of converting sewage sludge and food waste into valuable volatile fatty acids (VFAs).

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Published in Environmental Science and Ecotechnology, the research evaluates the environmental impact of this biorefinery, located in Galicia, Spain, which produces commercial-grade VFAs like acetic, propionic, and butyric acids.

The study highlights the biorefinery’s dual benefits: efficient waste management and reduced dependency on fossil fuels. Using pilot-scale data, the researchers demonstrated the scalability of this innovative technology, with food waste showing the best environmental performance per unit of product and sewage sludge excelling at handling large waste volumes.

Environmental performance

Key factors influencing environmental performance include transportation and chemical use. Sodium hydroxide, essential for pH control, contributed up to 80% of chemical-related impacts. Additionally, transportation accounted for a significant share of the carbon footprint. The study recommends strategies such as optimizing facility locations and replacing sodium hydroxide with alternatives like magnesium hydroxide, which could cut impacts by 53% and 29%, respectively.

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The biorefinery’s carbon footprint—5.5 to 8.6 kg CO₂ per kilogram of acetic acid—is on par with other bio-based technologies. However, further improvements in purification are needed to fully compete with petrochemical processes.

This study underscores biorefineries’ potential to revolutionize waste management, reduce environmental impacts, and promote a circular economy, marking a significant step toward sustainable production systems.

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