Development of an integrated biomass refinery process for whole cell biomass utilization of Chlorella sp. ABC-001

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 451; p. 138543
• Main Authors: Seon, Gyeongho, Kim, Minsik, Lee, Yong Wook, Cho, Jun Muk, Kim, Hogi, Park, Won-Kun, Chang, Yong Keun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2023
• Subjects: Chlorella sp. ABC-001; Ethanol fermentation; Extraction; Hydrolysis; Techno-economic analysis; Volume reduction; Hydrolysis; Techno-economic analysis; Ethanol fermentation; Extraction; Chlorella sp. ABC-001; Volume reduction
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.138543

[Display omitted] •Whole-cell biomass utilization was completed with newly integrated biorefinery.•Hydrolysis yielded 89 % of total carbohydrate within 4 min using optimized process.•Volume reduction decreased solvent usage by 75 % and recovered all oil within 20 min.•Bioethanol yield of sole hydrolysate was comparable with conventional YPD medium.•Newly developed process decreased OPEX and CAPEX by 82.7 % and 70.1 %, respectively. Microalgae are a promising source of biomass for the production of biofuels, but their use is currently infeasible because of changes in the biofuel market and the lack of an optimized refinery process. The biomass of oleaginous microalgae consists of up to 50% lipids and 50% carbohydrates and proteins, so the biorefinery process must be able to use whole cell biomass. In this work, an alternative process to the standard biorefinery approach of lipid extraction and treatment of lipid-extracted residue was developed and tested using oleaginous Chlorella sp. ABC-001. First, a hydrolysis process was optimized to achieve cell lysis. At 170 °C and 0.1 N H2SO4, 89.0% of total carbohydrates were hydrolyzed to monosaccharides within 4 min. Then, a volume reduction process (brief and mild centrifugation) was applied to reduce the extraction time and the use of organic solvent. By reducing the aqueous phase from the hydrolysate, all lipids were extracted by vortexing with just a quarter of the original volume (10 mL) within 20 min. Finally, after extraction the aqueous phase was utilized as the sole growth medium for ethanol production by Saccharomyces cerevisiae KL17. The resulting ethanol yield was 0.39 g ethanol/g sugar, comparable to that achieved using conventional yeast-peptone-dextrose (YPD) medium (0.41 g ethanol/g sugar). Furthermore, relative to the conventional process, techno-economic analysis confirmed that the newly developed process decreased operational expenditures by 82.7% and decreased capital expenditures by 70.1%.