One-stage single cell protein production from hemp (Cannabis sativa L.) biomass residues and cheese whey through sequential anaerobic-aerobic fermentation

Single cell protein (SCP) is emerging as a viable alternative to conventional protein sources thanks to their low environmental footprint and resource upcycling potential. This study investigated the production of SCP from hemp (Cannabis sativa L.) biomass residues (HBRs) and cheese whey (CW) in an innovative one-stage sequential anaerobic–aerobic fermentation process, through which the anaerobically produced volatile fatty acids (VFAs) were converted into SCP in the aerobic step. The best performance in terms of VFA and biomass yields (i.e., 0.85 mg HAc ∙ mg sCOD-1 and 0.21 g TSS ∙ g sCOD-1, respectively) as well as of protein content (i.e., 51 %) was obtained by working with a consecutive residence time of two and one days for, respectively, the anaerobic and the aerobic phase. A preliminary techno-economic assessment was performed to calculate the total production cost of the SCP, which ranged between 1.71 and 3.23 € ∙ kg TSS-1.