Waste-to-resource caproic acid production by anaerobic mixed microbial cultures: A review of recent developments

Author(s)

de Almeida, Felipe Filgueiras ; de Lima, Fabricio ; Gavazza, Savia ; Menezes, Osmar

• Document type: Journal article
• Source: BIOMASS & BIOENERGY; v. 197, p. 15-pg., 2025-03-14.

Abstract

Waste-to-resource technology transforms waste into valuable industrial chemicals, fostering sustainability and advancing the United Nations Sustainable Development Goals. Agroindustrial residues, often containing high concentrations of organic carbon, can increase the organic matter in sewage if not correctly managed. However, these residues can be converted into valuable chemicals through anaerobic digestion. Among the possible products, medium-chain carboxylic acids, such as caproic acid, are notable for their high commercial value (over $2500/ton) and applications as fuel additives and in fragrances and animal feed. Initial research focused on producing caproic acid using pure substrates and microbial isolates. Recently, the attention has shifted to utilizing open microbial cultures and organic wastes. We conducted a systematic literature review to consolidate findings and provide a comprehensive guideline on the caproic acid production from agroindustrial and food wastes via anaerobic digestion. This review examines the fundamentals of carbon chain elongation, the inhibition of competing microbial pathways, the optimization of various parameters, the use of different wastes and additives, the microbial communities, and the extraction methods for caproic acid recovery. This paper bridges the gap between theoretical knowledge and industrial application by providing insights to support the future scaling up of chain elongation through a comparison of different strategies. The focus was on advancing understanding and providing actionable guidance for researchers and industry professionals. (AU)

• FAPESP's process: 22/07127-5 - Vinasse as a business booster in the biorefinery concept: strategies to overcome anaerobic digestion bottlenecks to generate value-added products
• Grantee: Márcia Helena Rissato Zamariolli Damianovic
• Support Opportunities: Regular Research Grants