Biological valorization of volatile organic compounds to volatile fatty acids and upgraded bioproducts.

Volatile organic compounds (VOCs) are emitted from a wide range of industrial and indoor activities. They promote ozone and secondary organic aerosol formation and are linked to persistent health concerns. Most established abatement technologies are designed for rapid destruction, so VOC carbon is commonly mineralized to CO2 rather than retained for further use. This review reframes VOC control as a compliance-first resource-recovery problem and evaluates volatile fatty acids (VFAs) as the intermediate linking gas-phase biotreatment with downstream biomanufacturing. The evidence base is assessed by substrate class, reactor configuration, carbon-retention window, recovery interface, and scale-up maturity. Direct VOC-to-VFA evidence is currently strongest for simple oxygenated VOCs, especially methanol and short-chain alcohols, and for a limited number of mixed-VOC biotrickling filter cases. Aromatic VOCs remain substantially less mature because ring activation, bioavailability, toxicity, rapid routing of cleavage products to central metabolism, and poorly resolved extracellular carbon balances restrict recoverable-acid formation. The review further shows that front-end biofilters or biotrickling filters and downstream acidification, chain elongation, or polyhydroxyalkanoate production cannot be coupled by simple serial connection alone, because the liquid stream from dilute gas treatment is often too weak and too variable. Practical integration therefore requires side-stream equalization, liquid-phase concentration, in situ recovery, pH/redox control, and techno-economic benchmarking against catalytic or thermal destruction. The field should be regarded as a developing sequential strategy rather than a universally demonstrated platform.