Biohydrogen recovery by biosurfactant-induced ultrasonic fractionation of macroalgae, Sargassum tennerimum

Sargassum tennerimum (ST), being macroalgae, could be a renewable feed source for biohydrogen recovery. The recovery from this feed source can be improved by pretreatment of ST using saponin-coupled ultrasonic pretreatment (SCUPT). The solubilization ability of this pretreatment was investigated in this research after achieving preliminary optimized sonication conditions: sonication time—30 min and sonication power—200W. Maximum biomass soluble organic matter (BSOM) release (3100 mg/L) and BSOM solubilization percentage (41.42%) were attained at a biosurfactant concentration of 0.005 g/g of TS. The biohydrogen recovery capacity for solubilized biomass matter under dark fermentation was assessed and noted. The biohydrogen recovery was observed to be higher in SCUPT (116 mL/g COD) than in ultrasonic pretreatment (UPT) (48 mL/g COD) and control (10 mL/g COD). The maximum net positive energy of 0.0308 kWh and energy ratio of 2.06 achieved by SCUPT strongly indicate its Econo-feasibility of the process and practical application of ST and saponin in the biohydrogen recovery usage on a sustainable basis. Graphical abstract