RT journal article T1 Biomass to bioproducts by integrated biorefinery strategy: ultrasonic pretreatment, dark fermentation and enzyme hydrolysis A1 Rouabhia, Amer A1 Álvarez Gallego, Carlos José A1 Fernández Güelfo, Luis Alberto A2 Ingeniería Química y Tecnología de Alimentos A2 Tecnologías del Medio Ambiente K1 Ultrasound pretreatment K1 Dark fermentation K1 Enzyme hydrolysis K1 Total reducing sugars K1 Hydrogen K1 Volatile fatty acids AB The utilization of technology promoting energy indispensable to biorefinery applications drives the need for efficient biomass valorization strategies. This study investigates an integrated approach combining ultrasound pretreatment (US), dark fermentation, and enzyme hydrolysis (EH) to maximize the production of biohydrogen (H ), volatile fatty acids (VFA), total reducing sugars (TRS), and total proteins (PR) from lignocellulosic biomasses. Four feedstocks were examined: orange peel (OP), sugar beet pulp (SBP), brewers spent grain (BSG), and rice husk (RH). Ultrasound pretreatment at 120 min, 45 ◦ C, and 100 % of amplitude significantly enhanced the organic matter solubilization across all substrates, with OP exhibiting the highest solubilized organic matter (54.7 g O 2 /L; 25 g C/L, 21 g TRS/L and 8.7 g PR/L) with specific energy (Es) of 6.13 MJ/kg. During the dark fermentation process, the highest H 2 dry matter, while BSG and SBP, generate 17.9 mL H 2 production was obtained with OP, yielding 20.8 mL H /g dry matter, and 14.6 mL H 2 2 /g /g dry matter, respectively. Subsequently, VFAs production exhibited maximum yield with OP (5.37 g H-Ac/L), SBP (4.61 g H-Ac/L), and BSG (4.33 g H-Ac/L). Subsequent enzyme hydrolysis of the pretreated solid fractions further increased TRS concentrations, reaching 32.5 g/L for OP, 29.0 g/L for BSG, and 27.0 g/L for SBP. RH consistently exhibited the lowest yields across all bioproducts, attributed to its high lignin content and low enzymatic accessibility. Overall, OP proved to be the most promising substrate for integrated bioproduct recovery, demonstrating the efficiency of this biorefinery approach for lignocellulosic waste valorization. PB Elsevier SN 1873-2909 YR 2026 FD 2026 LK http://hdl.handle.net/10498/39072 UL http://hdl.handle.net/10498/39072 LA eng DS Repositorio Institucional de la Universidad de Cádiz RD 21-sep-2026