Fermentative hydrogen production from cheese whey with in-line, concentration gradient-driven butyric acid extraction
Dessì P, Asunis F, Ravishankar H, Cocco FG, De Gioannis G, Muntoni A, Lens PNL
Cocco, Francesco Giuseppe
De Gioannis, Giorgia
Lens, Piet N.L.
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Dessì, Paolo, Asunis, Fabiano, Ravishankar, Harish, Cocco, Francesco Giuseppe, De Gioannis, Giorgia, Muntoni, Aldo, & Lens, Piet N. L. (2020). Fermentative hydrogen production from cheese whey with in-line, concentration gradient-driven butyric acid extraction. International Journal of Hydrogen Energy, 45(46), 24453-24466. doi:https://doi.org/10.1016/j.ijhydene.2020.06.081
Hydrogen (H2) generation from cheese whey with simultaneous production and extraction of volatile fatty acids (VFAs) was studied in UASB reactors at two temperatures (20 and 35 °C) and pH values (5.0 and 4.5). The extraction module, installed through a recirculation loop, was a silicone tube coil submerged in water, which allows concentration-driven extraction of undissociated VFAs. Operating conditions were selected as a compromise for the recovery of both H2 and VFAs. Batch experiments showed a higher yield (0.9 mol H2 mol−1 glucoseeq.) at 35 °C and pH 5.0, regardless of the presence of the extraction module, whereas lower yields were obtained at pH 4.5 and 20 °C (0.5 and 0.3 mol H2 mol−1 glucoseeq., respectively). VFAs crossed the silicone membrane, with a strong preference for butyric over propionic and acetic acid due to its higher hydrophobicity. Sugars, lactic acid and nutrients were retained, resulting in an extracted solution of up to 2.5 g L−1 butyric acid with more than 90% purity. Continuous experiment confirmed those results, with production rates up to 2.0 L H2 L−1 d−1 and butyric acid extraction both in-line (from the UASB recirculation) and off-line (from the UASB effluent). In-line VFA extraction can reduce the operating costs of fermentation, facilitating downstream processing for the recovery of marketable VFAs without affecting the H2 production.